From nobody Wed Dec 17 06:12:58 2025 Received: from mail-wm1-f74.google.com (mail-wm1-f74.google.com [209.85.128.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 66DD4309F0B for ; Tue, 2 Dec 2025 09:36:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.74 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764668196; cv=none; b=oeF7fOFiV6TM1zhAUYXKFBf94vuYKrBy5TQfndRHYee4MNnxzr/BkolvEBb/BHqXY2uyGUT93FYhX3meXewUMWSyO+U1cYffT8SP4TDVyhZWm0Qpywm8NnK0spUbQAFW5GdzKEPwKKOv///XfBh8gGtasEcSafWDQT8hUbrZkqM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764668196; c=relaxed/simple; bh=WTMLyErWOb8zCrndU1XpyXrUk4hC/pi+xHnhtc2fDxE=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=HqjRnW0sPDgWf9kk5JorrtSdrp3LMK8EhvrJtHws6fVLgcKYxghYbPNWfqTK2yCMyi2DgQhbUx3Xvj3KdN4C2UAYAv7Gf2v5SjWfY/uBONiB4ZO6pM2uHicqwhVgtm2hAB5sHsZn1A3hbZLR3ZX8831oC4eR9BaQOWbfekfiPiI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--vdonnefort.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=4qzQbrXD; arc=none smtp.client-ip=209.85.128.74 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--vdonnefort.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="4qzQbrXD" Received: by mail-wm1-f74.google.com with SMTP id 5b1f17b1804b1-4776b0ada3dso39495955e9.0 for ; Tue, 02 Dec 2025 01:36:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1764668193; x=1765272993; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=BJMobDlS9cUjf1A94hhHD9cE0Yb81+orJSLPQk+5ukA=; b=4qzQbrXDCEKzVr2Av0QmY/gnmIkQGMZU/ZIjOw/dmqF6O2guAP9CZGJRS5VW+uswib y3i8iyaolgNhmcJZ8AuQge1pO+5R8owJ6C6vlFJkMOuV1Iefv7UyT8u1r2sxo2iemkHr C1j6TcPIcIOs9p2OUDaC88vNjnmwG2Li+/zUfQ5NKqlnK99PZ9y8eE26zu1Fk7ndIIKq 3jl7Rw4H+gzk/nSS74zUqlCSw1hJ23DzdUr7bKfazn7HV87YROBDMvyTULXM6AFQu88K uAAtdJbRRg4X76WxIgj0n1ZrzdXYEN0j842zmaYmLoqp3oe3b/y6GCLF+18ifEI+nvU6 Kkqg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1764668193; x=1765272993; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=BJMobDlS9cUjf1A94hhHD9cE0Yb81+orJSLPQk+5ukA=; b=hYFQXGdB72ciRnRaggvSnTLLUcVmQ1HlukgPKnSmHqIQ/Qc+cmnw/C7x++JLPL9VL/ Bn5A8I5bDMZQAa+DOF2745omVndtwIUMJSYt8rTLeM02VNnwCheF1gWs/93OT8kiCVgg 53+EpPv4KjErAGactlms1e6UTFTmk63k6nQrObB3hZXw57KIkUTAGlxzfDdnLrgg/E3j WrenyH1HwenZiN7g1wKsM1JMcuoPUWFkZ/BtlNIcY5J22USBVbSx4jtR7FC/+/Ki6YjZ JYuVXInDnSJeec4wiYc4Fg3Hyvm9nBnMgGo54AN9di1aielsKnrjqAN9sgIDYazNCtEA mR9Q== X-Forwarded-Encrypted: i=1; AJvYcCVsemNY0/KFdcYj9SGT3fsyCd+bAoci0tL5Q+788r+vqoV4GBoYA2ioIGOI76hGgLnibYU8owccLKL5Pjw=@vger.kernel.org X-Gm-Message-State: AOJu0YzBZjkVqzv/uo8zh+K353sAxmsAf2+Qobe8izQI2ti8X0JEfjoN /XT4FXX2Eo37mEJFg7SWPlj3OTMKprLjiFI/WRMkRQY6RVzIHJaOLmwY8b442G40Cnzdz/7qnp6 n+wtMLbZfbLbEPTVkriktHw== X-Google-Smtp-Source: AGHT+IFOZr0MC/hR67QKvdZl1NGr26HqxISCDgDHqiuErADTEPz6Od/NumPdYRXvv0diOBWVyP3bPEcOcKjqzEay X-Received: from wmlc8.prod.google.com ([2002:a7b:c848:0:b0:477:5a4b:d57f]) (user=vdonnefort job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:a41:b0:479:255f:8805 with SMTP id 5b1f17b1804b1-47926f80721mr15071745e9.4.1764668192874; Tue, 02 Dec 2025 01:36:32 -0800 (PST) Date: Tue, 2 Dec 2025 09:35:54 +0000 In-Reply-To: <20251202093623.2337860-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251202093623.2337860-1-vdonnefort@google.com> X-Mailer: git-send-email 2.52.0.107.ga0afd4fd5b-goog Message-ID: <20251202093623.2337860-2-vdonnefort@google.com> Subject: [PATCH v9 01/30] ring-buffer: Add page statistics to the meta-page From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-trace-kernel@vger.kernel.org, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, jstultz@google.com, qperret@google.com, will@kernel.org, aneesh.kumar@kernel.org, kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Add two fields pages_touched and pages_lost to the ring-buffer meta-page. Those fields are useful to get the number of used pages in the ring-buffer. Signed-off-by: Vincent Donnefort diff --git a/include/uapi/linux/trace_mmap.h b/include/uapi/linux/trace_mma= p.h index c102ef35d11e..e8185889a1c8 100644 --- a/include/uapi/linux/trace_mmap.h +++ b/include/uapi/linux/trace_mmap.h @@ -17,8 +17,8 @@ * @entries: Number of entries in the ring-buffer. * @overrun: Number of entries lost in the ring-buffer. * @read: Number of entries that have been read. - * @Reserved1: Internal use only. - * @Reserved2: Internal use only. + * @pages_lost: Number of pages overwritten by the writer. + * @pages_touched: Number of pages written by the writer. */ struct trace_buffer_meta { __u32 meta_page_size; @@ -39,8 +39,8 @@ struct trace_buffer_meta { __u64 overrun; __u64 read; =20 - __u64 Reserved1; - __u64 Reserved2; + __u64 pages_lost; + __u64 pages_touched; }; =20 #define TRACE_MMAP_IOCTL_GET_READER _IO('R', 0x20) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index afcd3747264d..048dde717b94 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -6113,6 +6113,8 @@ static void rb_update_meta_page(struct ring_buffer_pe= r_cpu *cpu_buffer) meta->entries =3D local_read(&cpu_buffer->entries); meta->overrun =3D local_read(&cpu_buffer->overrun); meta->read =3D cpu_buffer->read; + meta->pages_lost =3D local_read(&cpu_buffer->pages_lost); + meta->pages_touched =3D local_read(&cpu_buffer->pages_touched); =20 /* Some archs do not have data cache coherency between kernel and user-sp= ace */ flush_kernel_vmap_range(cpu_buffer->meta_page, PAGE_SIZE); --=20 2.52.0.107.ga0afd4fd5b-goog From nobody Wed Dec 17 06:12:58 2025 Received: from mail-wr1-f73.google.com (mail-wr1-f73.google.com [209.85.221.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 75E1730BB94 for ; Tue, 2 Dec 2025 09:36:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.73 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764668197; cv=none; b=QAhY2mFNcW/cadzz4lJ5dfWNLCxoLKq5ZM5Q8AMVTjlaDFBrIbYVjR696WrHiiu56niPIkA4cg2cVmc8tMfKeorEknYHoRjmy0nGZ4vChi69ECYS5p5GIbp2l+Ux4C9gHfuWnZEucGY8UwrbSkaufBiTUl4Wp7A9MOtWeSSfDQU= ARC-Message-Signature: i=1; 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charset="utf-8" The subbuf_ids field allows to point to a specific page from the ring-buffer based on its ID. As a preparation or the upcoming ring-buffer remote support, point this array to the buffer_page instead of the buffer_data_page. Signed-off-by: Vincent Donnefort diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 048dde717b94..aeff2ce6231a 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -519,7 +519,7 @@ struct ring_buffer_per_cpu { unsigned int mapped; unsigned int user_mapped; /* user space mapping */ struct mutex mapping_lock; - unsigned long *subbuf_ids; /* ID to subbuf VA */ + struct buffer_page **subbuf_ids; /* ID to subbuf VA */ struct trace_buffer_meta *meta_page; struct ring_buffer_cpu_meta *ring_meta; =20 @@ -7002,7 +7002,7 @@ static void rb_free_meta_page(struct ring_buffer_per_= cpu *cpu_buffer) } =20 static void rb_setup_ids_meta_page(struct ring_buffer_per_cpu *cpu_buffer, - unsigned long *subbuf_ids) + struct buffer_page **subbuf_ids) { struct trace_buffer_meta *meta =3D cpu_buffer->meta_page; unsigned int nr_subbufs =3D cpu_buffer->nr_pages + 1; @@ -7011,7 +7011,7 @@ static void rb_setup_ids_meta_page(struct ring_buffer= _per_cpu *cpu_buffer, int id =3D 0; =20 id =3D rb_page_id(cpu_buffer, cpu_buffer->reader_page, id); - subbuf_ids[id++] =3D (unsigned long)cpu_buffer->reader_page->page; + subbuf_ids[id++] =3D cpu_buffer->reader_page; cnt++; =20 first_subbuf =3D subbuf =3D rb_set_head_page(cpu_buffer); @@ -7021,7 +7021,7 @@ static void rb_setup_ids_meta_page(struct ring_buffer= _per_cpu *cpu_buffer, if (WARN_ON(id >=3D nr_subbufs)) break; =20 - subbuf_ids[id] =3D (unsigned long)subbuf->page; + subbuf_ids[id] =3D subbuf; =20 rb_inc_page(&subbuf); id++; @@ -7030,7 +7030,7 @@ static void rb_setup_ids_meta_page(struct ring_buffer= _per_cpu *cpu_buffer, =20 WARN_ON(cnt !=3D nr_subbufs); =20 - /* install subbuf ID to kern VA translation */ + /* install subbuf ID to bpage translation */ cpu_buffer->subbuf_ids =3D subbuf_ids; =20 meta->meta_struct_len =3D sizeof(*meta); @@ -7186,13 +7186,15 @@ static int __rb_map_vma(struct ring_buffer_per_cpu = *cpu_buffer, } =20 while (p < nr_pages) { + struct buffer_page *subbuf; struct page *page; int off =3D 0; 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Tue, 02 Dec 2025 01:36:34 -0800 (PST) Date: Tue, 2 Dec 2025 09:35:56 +0000 In-Reply-To: <20251202093623.2337860-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251202093623.2337860-1-vdonnefort@google.com> X-Mailer: git-send-email 2.52.0.107.ga0afd4fd5b-goog Message-ID: <20251202093623.2337860-4-vdonnefort@google.com> Subject: [PATCH v9 03/30] ring-buffer: Introduce ring-buffer remotes From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-trace-kernel@vger.kernel.org, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, jstultz@google.com, qperret@google.com, will@kernel.org, aneesh.kumar@kernel.org, kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" A ring-buffer remote is an entity outside of the kernel (most likely a firmware or a hypervisor) capable of writing events in a ring-buffer following the same format as the tracefs ring-buffer. To setup the ring-buffer on the kernel side, a description of the pages forming the ring-buffer (struct trace_buffer_desc) must be given. Callbacks (swap_reader_page and reset) must also be provided. It is expected from the remote to keep the meta-page updated. Signed-off-by: Vincent Donnefort diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h index 876358cfe1b1..41193c5b0d28 100644 --- a/include/linux/ring_buffer.h +++ b/include/linux/ring_buffer.h @@ -250,4 +250,62 @@ int ring_buffer_map(struct trace_buffer *buffer, int c= pu, struct vm_area_struct *vma); int ring_buffer_unmap(struct trace_buffer *buffer, int cpu); int ring_buffer_map_get_reader(struct trace_buffer *buffer, int cpu); + +struct ring_buffer_desc { + int cpu; + unsigned int nr_page_va; /* excludes the meta page */ + unsigned long meta_va; + unsigned long page_va[] __counted_by(nr_page_va); +}; + +struct trace_buffer_desc { + int nr_cpus; + size_t struct_len; + char __data[]; /* list of ring_buffer_desc */ +}; + +static inline struct ring_buffer_desc *__next_ring_buffer_desc(struct ring= _buffer_desc *desc) +{ + size_t len =3D struct_size(desc, page_va, desc->nr_page_va); + + return (struct ring_buffer_desc *)((void *)desc + len); +} + +static inline struct ring_buffer_desc *__first_ring_buffer_desc(struct tra= ce_buffer_desc *desc) +{ + return (struct ring_buffer_desc *)(&desc->__data[0]); +} + +static inline size_t trace_buffer_desc_size(size_t buffer_size, unsigned i= nt nr_cpus) +{ + unsigned int nr_pages =3D max(DIV_ROUND_UP(buffer_size, PAGE_SIZE), 2UL) = + 1; + struct ring_buffer_desc *rbdesc; + + return size_add(offsetof(struct trace_buffer_desc, __data), + size_mul(nr_cpus, struct_size(rbdesc, page_va, nr_pages))); +} + +#define for_each_ring_buffer_desc(__pdesc, __cpu, __trace_pdesc) \ + for (__pdesc =3D __first_ring_buffer_desc(__trace_pdesc), __cpu =3D 0; \ + (__cpu) < (__trace_pdesc)->nr_cpus; \ + (__cpu)++, __pdesc =3D __next_ring_buffer_desc(__pdesc)) + +struct ring_buffer_remote { + struct trace_buffer_desc *desc; + int (*swap_reader_page)(unsigned int cpu, void *priv); + int (*reset)(unsigned int cpu, void *priv); + void *priv; +}; + +int ring_buffer_poll_remote(struct trace_buffer *buffer, int cpu); + +struct trace_buffer * +__ring_buffer_alloc_remote(struct ring_buffer_remote *remote, + struct lock_class_key *key); + +#define ring_buffer_alloc_remote(remote) \ +({ \ + static struct lock_class_key __key; \ + __ring_buffer_alloc_remote(remote, &__key); \ +}) #endif /* _LINUX_RING_BUFFER_H */ diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index aeff2ce6231a..9c6c8e206e04 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -523,6 +523,8 @@ struct ring_buffer_per_cpu { struct trace_buffer_meta *meta_page; struct ring_buffer_cpu_meta *ring_meta; =20 + struct ring_buffer_remote *remote; + /* ring buffer pages to update, > 0 to add, < 0 to remove */ long nr_pages_to_update; struct list_head new_pages; /* new pages to add */ @@ -545,6 +547,8 @@ struct trace_buffer { =20 struct ring_buffer_per_cpu **buffers; =20 + struct ring_buffer_remote *remote; + struct hlist_node node; u64 (*clock)(void); =20 @@ -2197,6 +2201,40 @@ static void rb_meta_buffer_update(struct ring_buffer= _per_cpu *cpu_buffer, } } =20 +static struct ring_buffer_desc *ring_buffer_desc(struct trace_buffer_desc = *trace_desc, int cpu) +{ + struct ring_buffer_desc *desc, *end; + size_t len; + int i; + + if (!trace_desc) + return NULL; + + if (cpu >=3D trace_desc->nr_cpus) + return NULL; + + end =3D (struct ring_buffer_desc *)((void *)trace_desc + trace_desc->stru= ct_len); + desc =3D __first_ring_buffer_desc(trace_desc); + len =3D struct_size(desc, page_va, desc->nr_page_va); + desc =3D (struct ring_buffer_desc *)((void *)desc + (len * cpu)); + + if (desc < end && desc->cpu =3D=3D cpu) + return desc; + + /* Missing CPUs, need to linear search */ + for_each_ring_buffer_desc(desc, i, trace_desc) { + if (desc->cpu =3D=3D cpu) + return desc; + } + + return NULL; +} + +static void *ring_buffer_desc_page(struct ring_buffer_desc *desc, int page= _id) +{ + return page_id > desc->nr_page_va ? NULL : (void *)desc->page_va[page_id]; +} + static int __rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, long nr_pages, struct list_head *pages) { @@ -2204,6 +2242,7 @@ static int __rb_allocate_pages(struct ring_buffer_per= _cpu *cpu_buffer, struct ring_buffer_cpu_meta *meta =3D NULL; struct buffer_page *bpage, *tmp; bool user_thread =3D current->mm !=3D NULL; + struct ring_buffer_desc *desc =3D NULL; gfp_t mflags; long i; =20 @@ -2240,6 +2279,12 @@ static int __rb_allocate_pages(struct ring_buffer_pe= r_cpu *cpu_buffer, if (buffer->range_addr_start) meta =3D rb_range_meta(buffer, nr_pages, cpu_buffer->cpu); =20 + if (buffer->remote) { + desc =3D ring_buffer_desc(buffer->remote->desc, cpu_buffer->cpu); + if (!desc || WARN_ON(desc->nr_page_va !=3D (nr_pages + 1))) + return -EINVAL; + } + for (i =3D 0; i < nr_pages; i++) { struct page *page; =20 @@ -2266,6 +2311,16 @@ static int __rb_allocate_pages(struct ring_buffer_pe= r_cpu *cpu_buffer, rb_meta_buffer_update(cpu_buffer, bpage); bpage->range =3D 1; bpage->id =3D i + 1; + } else if (desc) { + void *p =3D ring_buffer_desc_page(desc, i + 1); + + if (WARN_ON(!p)) + goto free_pages; + + bpage->page =3D p; + bpage->range =3D 1; /* bpage->page can't be freed */ + bpage->id =3D i + 1; + cpu_buffer->subbuf_ids[i + 1] =3D bpage; } else { page =3D alloc_pages_node(cpu_to_node(cpu_buffer->cpu), mflags | __GFP_COMP | __GFP_ZERO, @@ -2369,6 +2424,30 @@ rb_allocate_cpu_buffer(struct trace_buffer *buffer, = long nr_pages, int cpu) if (cpu_buffer->ring_meta->head_buffer) rb_meta_buffer_update(cpu_buffer, bpage); bpage->range =3D 1; + } else if (buffer->remote) { + struct ring_buffer_desc *desc =3D ring_buffer_desc(buffer->remote->desc,= cpu); + + if (!desc) + goto fail_free_reader; + + cpu_buffer->remote =3D buffer->remote; + cpu_buffer->meta_page =3D (struct trace_buffer_meta *)(void *)desc->meta= _va; + cpu_buffer->nr_pages =3D nr_pages; + cpu_buffer->subbuf_ids =3D kcalloc(cpu_buffer->nr_pages + 1, + sizeof(*cpu_buffer->subbuf_ids), GFP_KERNEL); + if (!cpu_buffer->subbuf_ids) + goto fail_free_reader; + + /* Remote buffers are read-only and immutable */ + atomic_inc(&cpu_buffer->record_disabled); + atomic_inc(&cpu_buffer->resize_disabled); + + bpage->page =3D ring_buffer_desc_page(desc, cpu_buffer->meta_page->reade= r.id); + if (!bpage->page) + goto fail_free_reader; + + bpage->range =3D 1; + cpu_buffer->subbuf_ids[0] =3D bpage; } else { page =3D alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL | __GFP_COMP | __GFP_ZERO, @@ -2431,6 +2510,9 @@ static void rb_free_cpu_buffer(struct ring_buffer_per= _cpu *cpu_buffer) =20 irq_work_sync(&cpu_buffer->irq_work.work); =20 + if (cpu_buffer->remote) + kfree(cpu_buffer->subbuf_ids); + free_buffer_page(cpu_buffer->reader_page); =20 if (head) { @@ -2453,7 +2535,8 @@ static struct trace_buffer *alloc_buffer(unsigned lon= g size, unsigned flags, int order, unsigned long start, unsigned long end, unsigned long scratch_size, - struct lock_class_key *key) + struct lock_class_key *key, + struct ring_buffer_remote *remote) { struct trace_buffer *buffer __free(kfree) =3D NULL; long nr_pages; @@ -2493,6 +2576,8 @@ static struct trace_buffer *alloc_buffer(unsigned lon= g size, unsigned flags, if (!buffer->buffers) goto fail_free_cpumask; =20 + cpu =3D raw_smp_processor_id(); + /* If start/end are specified, then that overrides size */ if (start && end) { unsigned long buffers_start; @@ -2548,6 +2633,15 @@ static struct trace_buffer *alloc_buffer(unsigned lo= ng size, unsigned flags, buffer->range_addr_end =3D end; =20 rb_range_meta_init(buffer, nr_pages, scratch_size); + } else if (remote) { + struct ring_buffer_desc *desc =3D ring_buffer_desc(remote->desc, cpu); + + buffer->remote =3D remote; + /* The writer is remote. This ring-buffer is read-only */ + atomic_inc(&buffer->record_disabled); + nr_pages =3D desc->nr_page_va - 1; + if (nr_pages < 2) + goto fail_free_buffers; } else { =20 /* need at least two pages */ @@ -2556,7 +2650,6 @@ static struct trace_buffer *alloc_buffer(unsigned lon= g size, unsigned flags, nr_pages =3D 2; } =20 - cpu =3D raw_smp_processor_id(); cpumask_set_cpu(cpu, buffer->cpumask); buffer->buffers[cpu] =3D rb_allocate_cpu_buffer(buffer, nr_pages, cpu); if (!buffer->buffers[cpu]) @@ -2598,7 +2691,7 @@ struct trace_buffer *__ring_buffer_alloc(unsigned lon= g size, unsigned flags, struct lock_class_key *key) { /* Default buffer page size - one system page */ - return alloc_buffer(size, flags, 0, 0, 0, 0, key); + return alloc_buffer(size, flags, 0, 0, 0, 0, key, NULL); =20 } EXPORT_SYMBOL_GPL(__ring_buffer_alloc); @@ -2625,7 +2718,18 @@ struct trace_buffer *__ring_buffer_alloc_range(unsig= ned long size, unsigned flag struct lock_class_key *key) { return alloc_buffer(size, flags, order, start, start + range_size, - scratch_size, key); + scratch_size, key, NULL); +} + +/** + * __ring_buffer_alloc_remote - allocate a new ring_buffer from a remote + * @remote: Contains a description of the ring-buffer pages and remote cal= lbacks. + * @key: ring buffer reader_lock_key. + */ +struct trace_buffer *__ring_buffer_alloc_remote(struct ring_buffer_remote = *remote, + struct lock_class_key *key) +{ + return alloc_buffer(0, 0, 0, 0, 0, 0, key, remote); } =20 void *ring_buffer_meta_scratch(struct trace_buffer *buffer, unsigned int *= size) @@ -5233,6 +5337,16 @@ unsigned long ring_buffer_overruns(struct trace_buff= er *buffer) } EXPORT_SYMBOL_GPL(ring_buffer_overruns); =20 +static bool rb_read_remote_meta_page(struct ring_buffer_per_cpu *cpu_buffe= r) +{ + local_set(&cpu_buffer->entries, READ_ONCE(cpu_buffer->meta_page->entries)= ); + local_set(&cpu_buffer->overrun, READ_ONCE(cpu_buffer->meta_page->overrun)= ); + local_set(&cpu_buffer->pages_touched, READ_ONCE(cpu_buffer->meta_page->pa= ges_touched)); + local_set(&cpu_buffer->pages_lost, READ_ONCE(cpu_buffer->meta_page->pages= _lost)); + + return rb_num_of_entries(cpu_buffer); +} + static void rb_iter_reset(struct ring_buffer_iter *iter) { struct ring_buffer_per_cpu *cpu_buffer =3D iter->cpu_buffer; @@ -5387,7 +5501,43 @@ rb_update_iter_read_stamp(struct ring_buffer_iter *i= ter, } =20 static struct buffer_page * -rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) +__rb_get_reader_page_from_remote(struct ring_buffer_per_cpu *cpu_buffer) +{ + struct buffer_page *new_reader, *prev_reader; + + if (!rb_read_remote_meta_page(cpu_buffer)) + return NULL; + + /* More to read on the reader page */ + if (cpu_buffer->reader_page->read < rb_page_size(cpu_buffer->reader_page)= ) { + if (!cpu_buffer->reader_page->read) + cpu_buffer->read_stamp =3D cpu_buffer->reader_page->page->time_stamp; + return cpu_buffer->reader_page; + } + + prev_reader =3D cpu_buffer->subbuf_ids[cpu_buffer->meta_page->reader.id]; + + WARN_ON_ONCE(cpu_buffer->remote->swap_reader_page(cpu_buffer->cpu, + cpu_buffer->remote->priv)); + /* nr_pages doesn't include the reader page */ + if (WARN_ON_ONCE(cpu_buffer->meta_page->reader.id > cpu_buffer->nr_pages)) + return NULL; + + new_reader =3D cpu_buffer->subbuf_ids[cpu_buffer->meta_page->reader.id]; + + WARN_ON_ONCE(prev_reader =3D=3D new_reader); + + cpu_buffer->reader_page->page =3D new_reader->page; + cpu_buffer->reader_page->id =3D new_reader->id; + cpu_buffer->reader_page->read =3D 0; + cpu_buffer->read_stamp =3D cpu_buffer->reader_page->page->time_stamp; + cpu_buffer->lost_events =3D cpu_buffer->meta_page->reader.lost_events; + + return rb_page_size(cpu_buffer->reader_page) ? cpu_buffer->reader_page : = NULL; +} + +static struct buffer_page * +__rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) { struct buffer_page *reader =3D NULL; unsigned long bsize =3D READ_ONCE(cpu_buffer->buffer->subbuf_size); @@ -5557,6 +5707,13 @@ rb_get_reader_page(struct ring_buffer_per_cpu *cpu_b= uffer) return reader; } =20 +static struct buffer_page * +rb_get_reader_page(struct ring_buffer_per_cpu *cpu_buffer) +{ + return cpu_buffer->remote ? __rb_get_reader_page_from_remote(cpu_buffer) : + __rb_get_reader_page(cpu_buffer); +} + static void rb_advance_reader(struct ring_buffer_per_cpu *cpu_buffer) { struct ring_buffer_event *event; @@ -5957,7 +6114,7 @@ ring_buffer_read_start(struct trace_buffer *buffer, i= nt cpu, gfp_t flags) struct ring_buffer_per_cpu *cpu_buffer; struct ring_buffer_iter *iter; =20 - if (!cpumask_test_cpu(cpu, buffer->cpumask)) + if (!cpumask_test_cpu(cpu, buffer->cpumask) || buffer->remote) return NULL; =20 iter =3D kzalloc(sizeof(*iter), flags); @@ -6125,6 +6282,23 @@ rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer) { struct buffer_page *page; =20 + if (cpu_buffer->remote) { + if (!cpu_buffer->remote->reset) + return; + + cpu_buffer->remote->reset(cpu_buffer->cpu, cpu_buffer->remote->priv); + rb_read_remote_meta_page(cpu_buffer); + + /* Read related values, not covered by the meta-page */ + local_set(&cpu_buffer->pages_read, 0); + cpu_buffer->read =3D 0; + cpu_buffer->read_bytes =3D 0; + cpu_buffer->last_overrun =3D 0; + cpu_buffer->reader_page->read =3D 0; + + return; + } + rb_head_page_deactivate(cpu_buffer); =20 cpu_buffer->head_page @@ -6355,6 +6529,48 @@ bool ring_buffer_empty_cpu(struct trace_buffer *buff= er, int cpu) } EXPORT_SYMBOL_GPL(ring_buffer_empty_cpu); =20 +int ring_buffer_poll_remote(struct trace_buffer *buffer, int cpu) +{ + struct ring_buffer_per_cpu *cpu_buffer; + + if (cpu !=3D RING_BUFFER_ALL_CPUS) { + if (!cpumask_test_cpu(cpu, buffer->cpumask)) + return -EINVAL; + + cpu_buffer =3D buffer->buffers[cpu]; + + guard(raw_spinlock)(&cpu_buffer->reader_lock); + if (rb_read_remote_meta_page(cpu_buffer)) + rb_wakeups(buffer, cpu_buffer); + + return 0; + } + + cpus_read_lock(); + + /* + * Make sure all the ring buffers are up to date before we start reading + * them. + */ + for_each_buffer_cpu(buffer, cpu) { + cpu_buffer =3D buffer->buffers[cpu]; + + guard(raw_spinlock)(&cpu_buffer->reader_lock); + rb_read_remote_meta_page(cpu_buffer); + } + + for_each_buffer_cpu(buffer, cpu) { + cpu_buffer =3D buffer->buffers[cpu]; + + if (rb_num_of_entries(cpu_buffer)) + rb_wakeups(buffer, cpu_buffer); + } + + cpus_read_unlock(); + + return 0; +} + #ifdef CONFIG_RING_BUFFER_ALLOW_SWAP /** * ring_buffer_swap_cpu - swap a CPU buffer between two ring buffers @@ -6600,6 +6816,7 @@ int ring_buffer_read_page(struct trace_buffer *buffer, unsigned int commit; unsigned int read; u64 save_timestamp; + bool force_memcpy; =20 if (!cpumask_test_cpu(cpu, buffer->cpumask)) return -1; @@ -6637,6 +6854,8 @@ int ring_buffer_read_page(struct trace_buffer *buffer, /* Check if any events were dropped */ missed_events =3D cpu_buffer->lost_events; =20 + force_memcpy =3D cpu_buffer->mapped || cpu_buffer->remote; + /* * If this page has been partially read or * if len is not big enough to read the rest of the page or @@ -6646,7 +6865,7 @@ int ring_buffer_read_page(struct trace_buffer *buffer, */ if (read || (len < (commit - read)) || cpu_buffer->reader_page =3D=3D cpu_buffer->commit_page || - cpu_buffer->mapped) { + force_memcpy) { struct buffer_data_page *rpage =3D cpu_buffer->reader_page->page; unsigned int rpos =3D read; 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charset="utf-8" Hopefully, the remote will only swap pages on the kernel instruction (via the swap_reader_page() callback). This means we know at what point the ring-buffer geometry has changed. It is therefore possible to rearrange the kernel view of that ring-buffer to allow non-consuming read. Signed-off-by: Vincent Donnefort diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 9c6c8e206e04..cb674a9fc359 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -5347,10 +5347,51 @@ static bool rb_read_remote_meta_page(struct ring_bu= ffer_per_cpu *cpu_buffer) return rb_num_of_entries(cpu_buffer); } =20 +static void rb_update_remote_head(struct ring_buffer_per_cpu *cpu_buffer) +{ + struct buffer_page *next, *orig; + int retry =3D 3; + + orig =3D next =3D cpu_buffer->head_page; + rb_inc_page(&next); + + /* Run after the writer */ + while (cpu_buffer->head_page->page->time_stamp > next->page->time_stamp) { + rb_inc_page(&next); + + rb_list_head_clear(cpu_buffer->head_page->list.prev); + rb_inc_page(&cpu_buffer->head_page); + rb_set_list_to_head(cpu_buffer->head_page->list.prev); + + if (cpu_buffer->head_page =3D=3D orig) { + if (WARN_ON_ONCE(!(--retry))) + return; + } + } + + orig =3D cpu_buffer->commit_page =3D cpu_buffer->head_page; + retry =3D 3; + + while (cpu_buffer->commit_page->page->time_stamp < next->page->time_stamp= ) { + rb_inc_page(&next); + rb_inc_page(&cpu_buffer->commit_page); + + if (cpu_buffer->commit_page =3D=3D orig) { + if (WARN_ON_ONCE(!(--retry))) + return; + } + } +} + static void rb_iter_reset(struct ring_buffer_iter *iter) { struct ring_buffer_per_cpu *cpu_buffer =3D iter->cpu_buffer; =20 + if (cpu_buffer->remote) { + rb_read_remote_meta_page(cpu_buffer); + rb_update_remote_head(cpu_buffer); + } + /* Iterator usage is expected to have record disabled */ iter->head_page =3D cpu_buffer->reader_page; iter->head =3D cpu_buffer->reader_page->read; @@ -5503,7 +5544,7 @@ rb_update_iter_read_stamp(struct ring_buffer_iter *it= er, static struct buffer_page * __rb_get_reader_page_from_remote(struct ring_buffer_per_cpu *cpu_buffer) { - struct buffer_page *new_reader, *prev_reader; + struct buffer_page *new_reader, *prev_reader, *prev_head, *new_head, *las= t; =20 if (!rb_read_remote_meta_page(cpu_buffer)) return NULL; @@ -5527,10 +5568,32 @@ __rb_get_reader_page_from_remote(struct ring_buffer= _per_cpu *cpu_buffer) =20 WARN_ON_ONCE(prev_reader =3D=3D new_reader); =20 - cpu_buffer->reader_page->page =3D new_reader->page; - cpu_buffer->reader_page->id =3D new_reader->id; - cpu_buffer->reader_page->read =3D 0; - cpu_buffer->read_stamp =3D cpu_buffer->reader_page->page->time_stamp; + prev_head =3D new_reader; /* New reader was also the previous head */ + new_head =3D prev_head; + rb_inc_page(&new_head); + last =3D prev_head; + rb_dec_page(&last); + + /* Clear the old HEAD flag */ + rb_list_head_clear(cpu_buffer->head_page->list.prev); + + prev_reader->list.next =3D prev_head->list.next; + prev_reader->list.prev =3D prev_head->list.prev; + + /* Swap prev_reader with new_reader */ + last->list.next =3D &prev_reader->list; + new_head->list.prev =3D &prev_reader->list; + + new_reader->list.prev =3D &new_reader->list; + new_reader->list.next =3D &new_head->list; + + /* Reactivate the HEAD flag */ + rb_set_list_to_head(&last->list); 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Tue, 02 Dec 2025 01:36:36 -0800 (PST) Date: Tue, 2 Dec 2025 09:35:58 +0000 In-Reply-To: <20251202093623.2337860-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251202093623.2337860-1-vdonnefort@google.com> X-Mailer: git-send-email 2.52.0.107.ga0afd4fd5b-goog Message-ID: <20251202093623.2337860-6-vdonnefort@google.com> Subject: [PATCH v9 05/30] tracing: Introduce trace remotes From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-trace-kernel@vger.kernel.org, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, jstultz@google.com, qperret@google.com, will@kernel.org, aneesh.kumar@kernel.org, kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" A trace remote relies on ring-buffer remotes to read and control compatible tracing buffers, written by entity such as firmware or hypervisor. Add a Tracefs directory remotes/ that contains all instances of trace remotes. Each instance follows the same hierarchy as any other to ease the support by existing user-space tools. This currently does not provide any event support, which will come later. Signed-off-by: Vincent Donnefort diff --git a/include/linux/trace_remote.h b/include/linux/trace_remote.h new file mode 100644 index 000000000000..feb3433c2128 --- /dev/null +++ b/include/linux/trace_remote.h @@ -0,0 +1,80 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#ifndef _LINUX_TRACE_REMOTE_H +#define _LINUX_TRACE_REMOTE_H + +#include + +/** + * struct trace_remote_callbacks - Callbacks used by Tracefs to control th= e remote + * + * @load_trace_buffer: Called before Tracefs accesses the trace buffer fo= r the first + * time. Must return a &trace_buffer_desc + * (most likely filled with trace_remote_alloc_buffer()) + * @unload_trace_buffer: + * Called once Tracefs has no use for the trace buffer + * (most likely call trace_remote_free_buffer()) + * @enable_tracing: Called on Tracefs tracing_on. It is expected from the + * remote to allow writing. + * @swap_reader_page: Called when Tracefs consumes a new page from a + * ring-buffer. It is expected from the remote to isolate a + * new reader-page from the @cpu ring-buffer. + */ +struct trace_remote_callbacks { + struct trace_buffer_desc *(*load_trace_buffer)(unsigned long size, void *= priv); + void (*unload_trace_buffer)(struct trace_buffer_desc *desc, void *priv); + int (*enable_tracing)(bool enable, void *priv); + int (*swap_reader_page)(unsigned int cpu, void *priv); +}; + +/** + * trace_remote_register() - Register a Tracefs remote + * + * A trace remote is an entity, outside of the kernel (most likely firmwar= e or + * hypervisor) capable of writing events into a Tracefs compatible ring-bu= ffer. + * The kernel would then act as a reader. + * + * The registered remote will be found under the Tracefs directory + * remotes/. + * + * @name: Name of the remote, used for the Tracefs remotes/ directory. + * @cbs: Set of callbacks used to control the remote. + * @priv: Private data, passed to each callback from @cbs. + * @events: Array of events. &remote_event.name and &remote_event.id must = be + * filled by the caller. + * @nr_events: Number of events in the @events array. + * + * Return: 0 on success, negative error code on failure. + */ +int trace_remote_register(const char *name, struct trace_remote_callbacks = *cbs, void *priv); + +/** + * trace_remote_alloc_buffer() - Dynamically allocate a trace buffer + * + * Helper to dynamically allocate a set of pages (enough to cover @buffer_= size) + * for each CPU from @cpumask and fill @desc. Most likely called from + * &trace_remote_callbacks.load_trace_buffer. + * + * @desc: Uninitialized trace_buffer_desc + * @desc_size: Size of the trace_buffer_desc. Must be at least equal to + * trace_buffer_desc_size() + * @buffer_size: Size in bytes of each per-CPU ring-buffer + * @cpumask: CPUs to allocate a ring-buffer for + * + * Return: 0 on success, negative error code on failure. + */ +int trace_remote_alloc_buffer(struct trace_buffer_desc *desc, size_t desc_= size, size_t buffer_size, + const struct cpumask *cpumask); + +/** + * trace_remote_free_buffer() - Free trace buffer allocated with + * trace_remote_alloc_buffer() + * + * Most likely called from &trace_remote_callbacks.unload_trace_buffer. + * + * @desc: Descriptor of the per-CPU ring-buffers, originally filled by + * trace_remote_alloc_buffer() + */ +void trace_remote_free_buffer(struct trace_buffer_desc *desc); + +#endif diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index d2c79da81e4f..99af56d39eaf 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -1238,4 +1238,7 @@ config HIST_TRIGGERS_DEBUG =20 source "kernel/trace/rv/Kconfig" =20 +config TRACE_REMOTE + bool + endif # FTRACE diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile index dcb4e02afc5f..6dab341acc46 100644 --- a/kernel/trace/Makefile +++ b/kernel/trace/Makefile @@ -110,4 +110,5 @@ obj-$(CONFIG_FPROBE_EVENTS) +=3D trace_fprobe.o obj-$(CONFIG_TRACEPOINT_BENCHMARK) +=3D trace_benchmark.o obj-$(CONFIG_RV) +=3D rv/ =20 +obj-$(CONFIG_TRACE_REMOTE) +=3D trace_remote.o libftrace-y :=3D ftrace.o diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index d1e527cf2aae..5b2313ed1f12 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -9125,7 +9125,7 @@ static struct dentry *tracing_dentry_percpu(struct tr= ace_array *tr, int cpu) return tr->percpu_dir; } =20 -static struct dentry * +struct dentry * trace_create_cpu_file(const char *name, umode_t mode, struct dentry *paren= t, void *data, long cpu, const struct file_operations *fops) { diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 85eabb454bee..9ce2f0ed8f86 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -672,6 +672,12 @@ struct dentry *trace_create_file(const char *name, struct dentry *parent, void *data, const struct file_operations *fops); +struct dentry *trace_create_cpu_file(const char *name, + umode_t mode, + struct dentry *parent, + void *data, + long cpu, + const struct file_operations *fops); =20 =20 /** diff --git a/kernel/trace/trace_remote.c b/kernel/trace/trace_remote.c new file mode 100644 index 000000000000..3d80ff98fd90 --- /dev/null +++ b/kernel/trace/trace_remote.c @@ -0,0 +1,570 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2025 - Google LLC + * Author: Vincent Donnefort + */ + +#include +#include +#include +#include +#include +#include +#include + +#include "trace.h" + +#define TRACEFS_DIR "remotes" +#define TRACEFS_MODE_WRITE 0640 +#define TRACEFS_MODE_READ 0440 + +struct trace_remote_iterator { + struct trace_remote *remote; + struct trace_seq seq; + struct delayed_work poll_work; + unsigned long lost_events; + u64 ts; + int cpu; + int evt_cpu; +}; + +struct trace_remote { + struct trace_remote_callbacks *cbs; + void *priv; + struct trace_buffer *trace_buffer; + struct trace_buffer_desc *trace_buffer_desc; + unsigned long trace_buffer_size; + struct ring_buffer_remote rb_remote; + struct mutex lock; + unsigned int nr_readers; + unsigned int poll_ms; + bool tracing_on; +}; + +static bool trace_remote_loaded(struct trace_remote *remote) +{ + return remote->trace_buffer; +} + +static int trace_remote_load(struct trace_remote *remote) +{ + struct ring_buffer_remote *rb_remote =3D &remote->rb_remote; + + lockdep_assert_held(&remote->lock); + + if (trace_remote_loaded(remote)) + return 0; + + remote->trace_buffer_desc =3D remote->cbs->load_trace_buffer(remote->trac= e_buffer_size, + remote->priv); + if (IS_ERR(remote->trace_buffer_desc)) + return PTR_ERR(remote->trace_buffer_desc); + + rb_remote->desc =3D remote->trace_buffer_desc; + rb_remote->swap_reader_page =3D remote->cbs->swap_reader_page; + rb_remote->priv =3D remote->priv; + remote->trace_buffer =3D ring_buffer_alloc_remote(rb_remote); + if (!remote->trace_buffer) { + remote->cbs->unload_trace_buffer(remote->trace_buffer_desc, remote->priv= ); + return -ENOMEM; + } + + return 0; +} + +static void trace_remote_try_unload(struct trace_remote *remote) +{ + lockdep_assert_held(&remote->lock); + + if (!trace_remote_loaded(remote)) + return; + + /* The buffer is being read or writable */ + if (remote->nr_readers || remote->tracing_on) + return; + + /* The buffer has readable data */ + if (!ring_buffer_empty(remote->trace_buffer)) + return; + + ring_buffer_free(remote->trace_buffer); + remote->trace_buffer =3D NULL; + remote->cbs->unload_trace_buffer(remote->trace_buffer_desc, remote->priv); +} + +static int trace_remote_enable_tracing(struct trace_remote *remote) +{ + int ret; + + lockdep_assert_held(&remote->lock); + + if (remote->tracing_on) + return 0; + + ret =3D trace_remote_load(remote); + if (ret) + return ret; + + ret =3D remote->cbs->enable_tracing(true, remote->priv); + if (ret) { + trace_remote_try_unload(remote); + return ret; + } + + remote->tracing_on =3D true; + + return 0; +} + +static int trace_remote_disable_tracing(struct trace_remote *remote) +{ + int ret; + + lockdep_assert_held(&remote->lock); + + if (!remote->tracing_on) + return 0; + + ret =3D remote->cbs->enable_tracing(false, remote->priv); + if (ret) + return ret; + + ring_buffer_poll_remote(remote->trace_buffer, RING_BUFFER_ALL_CPUS); + remote->tracing_on =3D false; + trace_remote_try_unload(remote); + + return 0; +} + +static ssize_t +tracing_on_write(struct file *filp, const char __user *ubuf, size_t cnt, l= off_t *ppos) +{ + struct trace_remote *remote =3D filp->private_data; + unsigned long val; + int ret; + + ret =3D kstrtoul_from_user(ubuf, cnt, 10, &val); + if (ret) + return ret; + + guard(mutex)(&remote->lock); + + ret =3D val ? trace_remote_enable_tracing(remote) : trace_remote_disable_= tracing(remote); + if (ret) + return ret; + + return cnt; +} +static int tracing_on_show(struct seq_file *s, void *unused) +{ + struct trace_remote *remote =3D s->private; + + seq_printf(s, "%d\n", remote->tracing_on); + + return 0; +} +DEFINE_SHOW_STORE_ATTRIBUTE(tracing_on); + +static ssize_t buffer_size_kb_write(struct file *filp, const char __user *= ubuf, size_t cnt, + loff_t *ppos) +{ + struct trace_remote *remote =3D filp->private_data; + unsigned long val; + int ret; + + ret =3D kstrtoul_from_user(ubuf, cnt, 10, &val); + if (ret) + return ret; + + /* KiB to Bytes */ + if (!val || check_shl_overflow(val, 10, &val)) + return -EINVAL; + + guard(mutex)(&remote->lock); + + remote->trace_buffer_size =3D val; + + return cnt; +} + +static int buffer_size_kb_show(struct seq_file *s, void *unused) +{ + struct trace_remote *remote =3D s->private; + + seq_printf(s, "%lu (%s)\n", remote->trace_buffer_size >> 10, + trace_remote_loaded(remote) ? "loaded" : "unloaded"); + + return 0; +} +DEFINE_SHOW_STORE_ATTRIBUTE(buffer_size_kb); + +static int trace_remote_get(struct trace_remote *remote, int cpu) +{ + int ret; + + if (remote->nr_readers =3D=3D UINT_MAX) + return -EBUSY; + + ret =3D trace_remote_load(remote); + if (ret) + return ret; + + remote->nr_readers++; + + return 0; +} + +static void trace_remote_put(struct trace_remote *remote) +{ + if (WARN_ON(!remote->nr_readers)) + return; + + remote->nr_readers--; + if (remote->nr_readers) + return; + + trace_remote_try_unload(remote); +} + +static void __poll_remote(struct work_struct *work) +{ + struct delayed_work *dwork =3D to_delayed_work(work); + struct trace_remote_iterator *iter; + + iter =3D container_of(dwork, struct trace_remote_iterator, poll_work); + ring_buffer_poll_remote(iter->remote->trace_buffer, iter->cpu); + schedule_delayed_work((struct delayed_work *)work, + msecs_to_jiffies(iter->remote->poll_ms)); +} + +static struct trace_remote_iterator +*trace_remote_iter(struct trace_remote *remote, int cpu, enum tri_type typ= e) +{ + struct trace_remote_iterator *iter =3D NULL; + int ret; + + lockdep_assert_held(&remote->lock); + + + ret =3D trace_remote_get(remote, cpu); + if (ret) + return ERR_PTR(ret); + + /* Test the CPU */ + ret =3D ring_buffer_poll_remote(remote->trace_buffer, cpu); + if (ret) + goto err; + + iter =3D kzalloc(sizeof(*iter), GFP_KERNEL); + if (iter) { + iter->remote =3D remote; + iter->cpu =3D cpu; + trace_seq_init(&iter->seq); + INIT_DELAYED_WORK(&iter->poll_work, __poll_remote); + schedule_delayed_work(&iter->poll_work, msecs_to_jiffies(remote->poll_ms= )); + + return iter; + } + ret =3D -ENOMEM; + +err: + kfree(iter); + trace_remote_put(remote); + + return ERR_PTR(ret); +} + +static void trace_remote_iter_free(struct trace_remote_iterator *iter) +{ + struct trace_remote *remote; + + if (!iter) + return; + + remote =3D iter->remote; + + lockdep_assert_held(&remote->lock); + + kfree(iter); + trace_remote_put(remote); +} + +static bool trace_remote_iter_read_event(struct trace_remote_iterator *ite= r) +{ + struct trace_buffer *trace_buffer =3D iter->remote->trace_buffer; + int cpu =3D iter->cpu; + + if (cpu !=3D RING_BUFFER_ALL_CPUS) { + if (ring_buffer_empty_cpu(trace_buffer, cpu)) + return false; + + if (!ring_buffer_peek(trace_buffer, cpu, &iter->ts, &iter->lost_events)) + return false; + + iter->evt_cpu =3D cpu; + return true; + } + + iter->ts =3D U64_MAX; + for_each_possible_cpu(cpu) { + unsigned long lost_events; + u64 ts; + + if (ring_buffer_empty_cpu(trace_buffer, cpu)) + continue; + + if (!ring_buffer_peek(trace_buffer, cpu, &ts, &lost_events)) + continue; + + if (ts >=3D iter->ts) + continue; + + iter->ts =3D ts; + iter->evt_cpu =3D cpu; + iter->lost_events =3D lost_events; + } + + return iter->ts !=3D U64_MAX; +} + +static int trace_remote_iter_print(struct trace_remote_iterator *iter) +{ + unsigned long usecs_rem; + u64 ts =3D iter->ts; + + if (iter->lost_events) + trace_seq_printf(&iter->seq, "CPU:%d [LOST %lu EVENTS]\n", + iter->evt_cpu, iter->lost_events); + + do_div(ts, 1000); + usecs_rem =3D do_div(ts, USEC_PER_SEC); + + trace_seq_printf(&iter->seq, "[%03d]\t%5llu.%06lu: ", iter->evt_cpu, + ts, usecs_rem); + + return trace_seq_has_overflowed(&iter->seq) ? -EOVERFLOW : 0; +} + +static int trace_pipe_open(struct inode *inode, struct file *filp) +{ + struct trace_remote *remote =3D inode->i_private; + struct trace_remote_iterator *iter; + int cpu =3D RING_BUFFER_ALL_CPUS; + + if (inode->i_cdev) + cpu =3D (long)inode->i_cdev - 1; + + guard(mutex)(&remote->lock); + iter =3D trace_remote_iter(remote, cpu); + filp->private_data =3D iter; + + return IS_ERR(iter) ? PTR_ERR(iter) : 0; +} + +static int trace_pipe_release(struct inode *inode, struct file *filp) +{ + struct trace_remote_iterator *iter =3D filp->private_data; + struct trace_remote *remote =3D iter->remote; + + guard(mutex)(&remote->lock); + + trace_remote_iter_free(iter); + + return 0; +} + +static ssize_t trace_pipe_read(struct file *filp, char __user *ubuf, size_= t cnt, loff_t *ppos) +{ + struct trace_remote_iterator *iter =3D filp->private_data; + struct trace_buffer *trace_buffer =3D iter->remote->trace_buffer; + int ret; + +copy_to_user: + ret =3D trace_seq_to_user(&iter->seq, ubuf, cnt); + if (ret !=3D -EBUSY) + return ret; + + trace_seq_init(&iter->seq); + + ret =3D ring_buffer_wait(trace_buffer, iter->cpu, 0, NULL, NULL); + if (ret < 0) + return ret; + + while (trace_remote_iter_read_event(iter)) { + int prev_len =3D iter->seq.seq.len; + + if (trace_remote_iter_print_event(iter)) { + iter->seq.seq.len =3D prev_len; + break; + } + + ring_buffer_consume(trace_buffer, iter->evt_cpu, NULL, NULL); + } + + goto copy_to_user; +} + +static const struct file_operations trace_pipe_fops =3D { + .open =3D trace_pipe_open, + .read =3D trace_pipe_read, + .release =3D trace_pipe_release, +}; + +static int trace_remote_init_tracefs(const char *name, struct trace_remote= *remote) +{ + struct dentry *remote_d, *percpu_d; + static struct dentry *root; + static DEFINE_MUTEX(lock); + bool root_inited =3D false; + int cpu; + + guard(mutex)(&lock); + + if (!root) { + root =3D tracefs_create_dir(TRACEFS_DIR, NULL); + if (!root) { + pr_err("Failed to create tracefs dir "TRACEFS_DIR"\n"); + return -ENOMEM; + } + root_inited =3D true; + } + + remote_d =3D tracefs_create_dir(name, root); + if (!remote_d) { + pr_err("Failed to create tracefs dir "TRACEFS_DIR"%s/\n", name); + goto err; + } + + if (!trace_create_file("tracing_on", TRACEFS_MODE_WRITE, remote_d, remote, + &tracing_on_fops) || + !trace_create_file("buffer_size_kb", TRACEFS_MODE_WRITE, remote_d, re= mote, + &buffer_size_kb_fops) || + !trace_create_file("trace_pipe", TRACEFS_MODE_READ, remote_d, remote, + &trace_pipe_fops)) + goto err; + + percpu_d =3D tracefs_create_dir("per_cpu", remote_d); + if (!percpu_d) { + pr_err("Failed to create tracefs dir "TRACEFS_DIR"%s/per_cpu/\n", name); + goto err; + } + + for_each_possible_cpu(cpu) { + struct dentry *cpu_d; + char cpu_name[16]; + + snprintf(cpu_name, sizeof(cpu_name), "cpu%d", cpu); + cpu_d =3D tracefs_create_dir(cpu_name, percpu_d); + if (!cpu_d) { + pr_err("Failed to create tracefs dir "TRACEFS_DIR"%s/percpu/cpu%d\n", + name, cpu); + goto err; + } + + if (!trace_create_cpu_file("trace_pipe", TRACEFS_MODE_READ, cpu_d, remot= e, cpu, + &trace_pipe_fops)) + goto err; + } + + return 0; + +err: + if (root_inited) { + tracefs_remove(root); + root =3D NULL; + } else { + tracefs_remove(remote_d); + } + + return -ENOMEM; +} + +int trace_remote_register(const char *name, struct trace_remote_callbacks = *cbs, void *priv) +{ + struct trace_remote *remote; + + remote =3D kzalloc(sizeof(*remote), GFP_KERNEL); + if (!remote) + return -ENOMEM; + + remote->cbs =3D cbs; + remote->priv =3D priv; + remote->trace_buffer_size =3D 7 << 10; + remote->poll_ms =3D 100; + mutex_init(&remote->lock); + + if (trace_remote_init_tracefs(name, remote)) { + kfree(remote); + return -ENOMEM; + } + + return 0; +} +EXPORT_SYMBOL_GPL(trace_remote_register); + +void trace_remote_free_buffer(struct trace_buffer_desc *desc) +{ + struct ring_buffer_desc *rb_desc; + int cpu; + + for_each_ring_buffer_desc(rb_desc, cpu, desc) { + unsigned int id; + + free_page(rb_desc->meta_va); + + for (id =3D 0; id < rb_desc->nr_page_va; id++) + free_page(rb_desc->page_va[id]); + } +} +EXPORT_SYMBOL_GPL(trace_remote_free_buffer); + +int trace_remote_alloc_buffer(struct trace_buffer_desc *desc, size_t desc_= size, size_t buffer_size, + const struct cpumask *cpumask) +{ + unsigned int nr_pages =3D max(DIV_ROUND_UP(buffer_size, PAGE_SIZE), 2UL) = + 1; + void *desc_end =3D desc + desc_size; + struct ring_buffer_desc *rb_desc; + int cpu, ret =3D -ENOMEM; + + if (desc_size < struct_size(desc, __data, 0)) + return -EINVAL; + + desc->nr_cpus =3D 0; + desc->struct_len =3D struct_size(desc, __data, 0); + + rb_desc =3D (struct ring_buffer_desc *)&desc->__data[0]; + + for_each_cpu(cpu, cpumask) { + unsigned int id; + + if ((void *)rb_desc + struct_size(rb_desc, page_va, nr_pages) > desc_end= ) { + ret =3D -EINVAL; + goto err; + } + + rb_desc->cpu =3D cpu; + rb_desc->nr_page_va =3D 0; + rb_desc->meta_va =3D (unsigned long)__get_free_page(GFP_KERNEL); + if (!rb_desc->meta_va) + goto err; + + for (id =3D 0; id < nr_pages; id++) { + rb_desc->page_va[id] =3D (unsigned long)__get_free_page(GFP_KERNEL); + if (!rb_desc->page_va[id]) + goto err; + + rb_desc->nr_page_va++; + } + desc->nr_cpus++; + desc->struct_len +=3D offsetof(struct ring_buffer_desc, page_va); + desc->struct_len +=3D struct_size(rb_desc, page_va, rb_desc->nr_page_va); + rb_desc =3D __next_ring_buffer_desc(rb_desc); + } + + return 0; + +err: + trace_remote_free_buffer(desc); + return ret; +} +EXPORT_SYMBOL_GPL(trace_remote_alloc_buffer); --=20 2.52.0.107.ga0afd4fd5b-goog From nobody Wed Dec 17 06:12:58 2025 Received: from mail-wr1-f73.google.com (mail-wr1-f73.google.com [209.85.221.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7126830E854 for ; 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Tue, 02 Dec 2025 01:36:36 -0800 (PST) Date: Tue, 2 Dec 2025 09:35:59 +0000 In-Reply-To: <20251202093623.2337860-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251202093623.2337860-1-vdonnefort@google.com> X-Mailer: git-send-email 2.52.0.107.ga0afd4fd5b-goog Message-ID: <20251202093623.2337860-7-vdonnefort@google.com> Subject: [PATCH v9 06/30] tracing: Add reset to trace remotes From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-trace-kernel@vger.kernel.org, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, jstultz@google.com, qperret@google.com, will@kernel.org, aneesh.kumar@kernel.org, kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Allow to reset the trace remote buffer by writing to the Tracefs "trace" file. This is similar to the regular Tracefs interface. Signed-off-by: Vincent Donnefort diff --git a/include/linux/trace_remote.h b/include/linux/trace_remote.h index feb3433c2128..55754ef78104 100644 --- a/include/linux/trace_remote.h +++ b/include/linux/trace_remote.h @@ -18,6 +18,8 @@ * remote to allow writing. * @swap_reader_page: Called when Tracefs consumes a new page from a * ring-buffer. It is expected from the remote to isolate a + * @reset: Called on `echo 0 > trace`. It is expected from the + * remote to reset all ring-buffer pages. * new reader-page from the @cpu ring-buffer. */ struct trace_remote_callbacks { @@ -25,6 +27,7 @@ struct trace_remote_callbacks { void (*unload_trace_buffer)(struct trace_buffer_desc *desc, void *priv); int (*enable_tracing)(bool enable, void *priv); int (*swap_reader_page)(unsigned int cpu, void *priv); + int (*reset)(unsigned int cpu, void *priv); }; =20 /** diff --git a/kernel/trace/trace_remote.c b/kernel/trace/trace_remote.c index 3d80ff98fd90..49c4ae127533 100644 --- a/kernel/trace/trace_remote.c +++ b/kernel/trace/trace_remote.c @@ -63,6 +63,7 @@ static int trace_remote_load(struct trace_remote *remote) rb_remote->desc =3D remote->trace_buffer_desc; rb_remote->swap_reader_page =3D remote->cbs->swap_reader_page; rb_remote->priv =3D remote->priv; + rb_remote->reset =3D remote->cbs->reset; remote->trace_buffer =3D ring_buffer_alloc_remote(rb_remote); if (!remote->trace_buffer) { remote->cbs->unload_trace_buffer(remote->trace_buffer_desc, remote->priv= ); @@ -136,6 +137,21 @@ static int trace_remote_disable_tracing(struct trace_r= emote *remote) return 0; } =20 +static void trace_remote_reset(struct trace_remote *remote, int cpu) +{ + lockdep_assert_held(&remote->lock); + + if (!trace_remote_loaded(remote)) + return; + + if (cpu =3D=3D RING_BUFFER_ALL_CPUS) + ring_buffer_reset(remote->trace_buffer); + else + ring_buffer_reset_cpu(remote->trace_buffer, cpu); + + trace_remote_try_unload(remote); +} + static ssize_t tracing_on_write(struct file *filp, const char __user *ubuf, size_t cnt, l= off_t *ppos) { @@ -410,6 +426,26 @@ static const struct file_operations trace_pipe_fops = =3D { .release =3D trace_pipe_release, }; =20 +static ssize_t trace_write(struct file *filp, const char __user *ubuf, siz= e_t cnt, loff_t *ppos) +{ + struct inode *inode =3D file_inode(filp); + struct trace_remote *remote =3D inode->i_private; + int cpu =3D RING_BUFFER_ALL_CPUS; + + if (inode->i_cdev) + cpu =3D (long)inode->i_cdev - 1; + + guard(mutex)(&remote->lock); + + trace_remote_reset(remote, cpu); + + return cnt; +} + +static const struct file_operations trace_fops =3D { + .write =3D trace_write, +}; + static int trace_remote_init_tracefs(const char *name, struct trace_remote= *remote) { struct dentry *remote_d, *percpu_d; @@ -440,7 +476,9 @@ static int trace_remote_init_tracefs(const char *name, = struct trace_remote *remo !trace_create_file("buffer_size_kb", TRACEFS_MODE_WRITE, remote_d, re= mote, &buffer_size_kb_fops) || !trace_create_file("trace_pipe", TRACEFS_MODE_READ, remote_d, remote, - &trace_pipe_fops)) + &trace_pipe_fops) || + !trace_create_file("trace", TRACEFS_MODE_WRITE, remote_d, remote, + &trace_fops)) goto err; =20 percpu_d =3D tracefs_create_dir("per_cpu", remote_d); @@ -462,7 +500,9 @@ static int trace_remote_init_tracefs(const char *name, = struct trace_remote *remo } =20 if (!trace_create_cpu_file("trace_pipe", TRACEFS_MODE_READ, cpu_d, remot= e, cpu, - &trace_pipe_fops)) + &trace_pipe_fops) || + !trace_create_cpu_file("trace", TRACEFS_MODE_WRITE, cpu_d, remote, c= pu, + &trace_fops)) goto err; 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charset="utf-8" Allow reading the trace file for trace remotes. This performs a non-consuming read of the trace buffer. Signed-off-by: Vincent Donnefort diff --git a/kernel/trace/trace_remote.c b/kernel/trace/trace_remote.c index 49c4ae127533..a744bbf48e88 100644 --- a/kernel/trace/trace_remote.c +++ b/kernel/trace/trace_remote.c @@ -18,14 +18,25 @@ #define TRACEFS_MODE_WRITE 0640 #define TRACEFS_MODE_READ 0440 =20 +enum tri_type { + TRI_CONSUMING, + TRI_NONCONSUMING, +}; + struct trace_remote_iterator { struct trace_remote *remote; struct trace_seq seq; struct delayed_work poll_work; unsigned long lost_events; u64 ts; + union { + struct ring_buffer_iter **rb_iters; + struct ring_buffer_iter *rb_iter; + }; int cpu; int evt_cpu; + loff_t pos; + enum tri_type type; }; =20 struct trace_remote { @@ -36,6 +47,8 @@ struct trace_remote { unsigned long trace_buffer_size; struct ring_buffer_remote rb_remote; struct mutex lock; + struct rw_semaphore reader_lock; + struct rw_semaphore *pcpu_reader_locks; unsigned int nr_readers; unsigned int poll_ms; bool tracing_on; @@ -225,6 +238,20 @@ static int trace_remote_get(struct trace_remote *remot= e, int cpu) if (ret) return ret; =20 + if (cpu !=3D RING_BUFFER_ALL_CPUS && !remote->pcpu_reader_locks) { + int lock_cpu; + + remote->pcpu_reader_locks =3D kcalloc(nr_cpu_ids, sizeof(*remote->pcpu_r= eader_locks), + GFP_KERNEL); + if (!remote->pcpu_reader_locks) { + trace_remote_try_unload(remote); + return -ENOMEM; + } + + for_each_possible_cpu(lock_cpu) + init_rwsem(&remote->pcpu_reader_locks[lock_cpu]); + } + remote->nr_readers++; =20 return 0; @@ -239,6 +266,9 @@ static void trace_remote_put(struct trace_remote *remot= e) if (remote->nr_readers) return; =20 + kfree(remote->pcpu_reader_locks); + remote->pcpu_reader_locks =3D NULL; + trace_remote_try_unload(remote); } =20 @@ -253,6 +283,48 @@ static void __poll_remote(struct work_struct *work) msecs_to_jiffies(iter->remote->poll_ms)); } =20 +static int __alloc_ring_buffer_iter(struct trace_remote_iterator *iter, in= t cpu) +{ + bool once =3D false; + + if (cpu !=3D RING_BUFFER_ALL_CPUS) { + iter->rb_iter =3D ring_buffer_read_start(iter->remote->trace_buffer, cpu= , GFP_KERNEL); + + return iter->rb_iter ? 0 : -ENOMEM; + } + + iter->rb_iters =3D kcalloc(nr_cpu_ids, sizeof(*iter->rb_iters), GFP_KERNE= L); + if (!iter->rb_iters) + return -ENOMEM; + + for_each_possible_cpu(cpu) { + iter->rb_iters[cpu] =3D ring_buffer_read_start(iter->remote->trace_buffe= r, cpu, + GFP_KERNEL); + if (iter->rb_iters[cpu]) + once =3D true; + } + + return once ? 0 : -ENOMEM; +} + +static void __free_ring_buffer_iter(struct trace_remote_iterator *iter, in= t cpu) +{ + if (!iter->rb_iter) + return; + + if (cpu !=3D RING_BUFFER_ALL_CPUS) { + ring_buffer_read_finish(iter->rb_iter); + return; + } + + for_each_possible_cpu(cpu) { + if (iter->rb_iters[cpu]) + ring_buffer_read_finish(iter->rb_iters[cpu]); + } + + kfree(iter->rb_iters); +} + static struct trace_remote_iterator *trace_remote_iter(struct trace_remote *remote, int cpu, enum tri_type typ= e) { @@ -261,6 +333,8 @@ static struct trace_remote_iterator =20 lockdep_assert_held(&remote->lock); =20 + if (type =3D=3D TRI_NONCONSUMING && !trace_remote_loaded(remote)) + return NULL; =20 ret =3D trace_remote_get(remote, cpu); if (ret) @@ -275,9 +349,21 @@ static struct trace_remote_iterator if (iter) { iter->remote =3D remote; iter->cpu =3D cpu; + iter->type =3D type; trace_seq_init(&iter->seq); - INIT_DELAYED_WORK(&iter->poll_work, __poll_remote); - schedule_delayed_work(&iter->poll_work, msecs_to_jiffies(remote->poll_ms= )); + + switch (type) { + case TRI_CONSUMING: + INIT_DELAYED_WORK(&iter->poll_work, __poll_remote); + schedule_delayed_work(&iter->poll_work, msecs_to_jiffies(remote->poll_m= s)); + break; + case TRI_NONCONSUMING: + ret =3D __alloc_ring_buffer_iter(iter, cpu); + break; + } + + if (ret) + goto err; =20 return iter; } @@ -301,10 +387,100 @@ static void trace_remote_iter_free(struct trace_remo= te_iterator *iter) =20 lockdep_assert_held(&remote->lock); =20 + switch (iter->type) { + case TRI_CONSUMING: + cancel_delayed_work_sync(&iter->poll_work); + break; + case TRI_NONCONSUMING: + __free_ring_buffer_iter(iter, iter->cpu); + break; + } + kfree(iter); trace_remote_put(remote); } =20 +static void trace_remote_iter_read_start(struct trace_remote_iterator *ite= r) +{ + struct trace_remote *remote =3D iter->remote; + int cpu =3D iter->cpu; + + /* Acquire global reader lock */ + if (cpu =3D=3D RING_BUFFER_ALL_CPUS && iter->type =3D=3D TRI_CONSUMING) + down_write(&remote->reader_lock); + else + down_read(&remote->reader_lock); + + if (cpu =3D=3D RING_BUFFER_ALL_CPUS) + return; + + /* + * No need for the remote lock here, iter holds a reference on + * remote->nr_readers + */ + + /* Get the per-CPU one */ + if (WARN_ON_ONCE(!remote->pcpu_reader_locks)) + return; + + if (iter->type =3D=3D TRI_CONSUMING) + down_write(&remote->pcpu_reader_locks[cpu]); + else + down_read(&remote->pcpu_reader_locks[cpu]); +} + +static void trace_remote_iter_read_finished(struct trace_remote_iterator *= iter) +{ + struct trace_remote *remote =3D iter->remote; + int cpu =3D iter->cpu; + + /* Release per-CPU reader lock */ + if (cpu !=3D RING_BUFFER_ALL_CPUS) { + /* + * No need for the remote lock here, iter holds a reference on + * remote->nr_readers + */ + if (iter->type =3D=3D TRI_CONSUMING) + up_write(&remote->pcpu_reader_locks[cpu]); + else + up_read(&remote->pcpu_reader_locks[cpu]); + } + + /* Release global reader lock */ + if (cpu =3D=3D RING_BUFFER_ALL_CPUS && iter->type =3D=3D TRI_CONSUMING) + up_write(&remote->reader_lock); + else + up_read(&remote->reader_lock); +} + +static struct ring_buffer_iter *__get_rb_iter(struct trace_remote_iterator= *iter, int cpu) +{ + return iter->cpu !=3D RING_BUFFER_ALL_CPUS ? iter->rb_iter : iter->rb_ite= rs[cpu]; +} + +static struct ring_buffer_event * +__peek_event(struct trace_remote_iterator *iter, int cpu, u64 *ts, unsigne= d long *lost_events) +{ + struct ring_buffer_event *rb_evt; + struct ring_buffer_iter *rb_iter; + + switch (iter->type) { + case TRI_CONSUMING: + return ring_buffer_peek(iter->remote->trace_buffer, cpu, ts, lost_events= ); + case TRI_NONCONSUMING: + rb_iter =3D __get_rb_iter(iter, cpu); + rb_evt =3D ring_buffer_iter_peek(rb_iter, ts); + if (!rb_evt) + return NULL; + + *lost_events =3D ring_buffer_iter_dropped(rb_iter); + + return rb_evt; + } + + return NULL; +} + static bool trace_remote_iter_read_event(struct trace_remote_iterator *ite= r) { struct trace_buffer *trace_buffer =3D iter->remote->trace_buffer; @@ -314,7 +490,7 @@ static bool trace_remote_iter_read_event(struct trace_r= emote_iterator *iter) if (ring_buffer_empty_cpu(trace_buffer, cpu)) return false; =20 - if (!ring_buffer_peek(trace_buffer, cpu, &iter->ts, &iter->lost_events)) + if (!__peek_event(iter, cpu, &iter->ts, &iter->lost_events)) return false; =20 iter->evt_cpu =3D cpu; @@ -329,7 +505,7 @@ static bool trace_remote_iter_read_event(struct trace_r= emote_iterator *iter) if (ring_buffer_empty_cpu(trace_buffer, cpu)) continue; =20 - if (!ring_buffer_peek(trace_buffer, cpu, &ts, &lost_events)) + if (!__peek_event(iter, cpu, &ts, &lost_events)) continue; =20 if (ts >=3D iter->ts) @@ -343,7 +519,21 @@ static bool trace_remote_iter_read_event(struct trace_= remote_iterator *iter) return iter->ts !=3D U64_MAX; } =20 -static int trace_remote_iter_print(struct trace_remote_iterator *iter) +static void trace_remote_iter_move(struct trace_remote_iterator *iter) +{ + struct trace_buffer *trace_buffer =3D iter->remote->trace_buffer; + + switch (iter->type) { + case TRI_CONSUMING: + ring_buffer_consume(trace_buffer, iter->evt_cpu, NULL, NULL); + break; + case TRI_NONCONSUMING: + ring_buffer_iter_advance(__get_rb_iter(iter, iter->evt_cpu)); + break; + } +} + +static int trace_remote_iter_print_event(struct trace_remote_iterator *ite= r) { unsigned long usecs_rem; u64 ts =3D iter->ts; @@ -371,7 +561,11 @@ static int trace_pipe_open(struct inode *inode, struct= file *filp) cpu =3D (long)inode->i_cdev - 1; =20 guard(mutex)(&remote->lock); - iter =3D trace_remote_iter(remote, cpu); + + iter =3D trace_remote_iter(remote, cpu, TRI_CONSUMING); + if (IS_ERR(iter)) + return PTR_ERR(iter); + filp->private_data =3D iter; =20 return IS_ERR(iter) ? PTR_ERR(iter) : 0; @@ -406,6 +600,8 @@ static ssize_t trace_pipe_read(struct file *filp, char = __user *ubuf, size_t cnt, if (ret < 0) return ret; =20 + trace_remote_iter_read_start(iter); + while (trace_remote_iter_read_event(iter)) { int prev_len =3D iter->seq.seq.len; =20 @@ -414,9 +610,11 @@ static ssize_t trace_pipe_read(struct file *filp, char= __user *ubuf, size_t cnt, break; } =20 - ring_buffer_consume(trace_buffer, iter->evt_cpu, NULL, NULL); + trace_remote_iter_move(iter); } =20 + trace_remote_iter_read_finished(iter); + goto copy_to_user; } =20 @@ -426,6 +624,119 @@ static const struct file_operations trace_pipe_fops = =3D { .release =3D trace_pipe_release, }; =20 +static void *trace_seq_start(struct seq_file *m, loff_t *pos) +{ + struct trace_remote_iterator *iter =3D m->private; + loff_t i =3D *pos; + + if (!iter) + return NULL; + + if (iter->pos <=3D *pos) { + do { + if (!trace_remote_iter_read_event(iter)) + return NULL; + + trace_remote_iter_move(iter); + iter->pos++; + } while (i--); + } + + return iter; +} + +static void *trace_seq_next(struct seq_file *m, void *v, loff_t *pos) +{ + struct trace_remote_iterator *iter =3D m->private; + + ++*pos; + + if (!iter || !trace_remote_iter_read_event(iter)) + return NULL; + + trace_remote_iter_move(iter); + iter->pos++; + + return iter; +} + +static int trace_seq_show(struct seq_file *m, void *v) +{ + struct trace_remote_iterator *iter =3D v; + + trace_seq_init(&iter->seq); + + if (trace_remote_iter_print_event(iter)) { + seq_printf(m, "[EVENT %d PRINT TOO BIG]\n", iter->evt->id); + return 0; + } + + return trace_print_seq(m, &iter->seq); +} + +static void trace_seq_stop(struct seq_file *s, void *v) { } + +static const struct seq_operations trace_seq_ops =3D { + .start =3D trace_seq_start, + .next =3D trace_seq_next, + .show =3D trace_seq_show, + .stop =3D trace_seq_stop, +}; + +static int trace_open(struct inode *inode, struct file *filp) +{ + struct trace_remote *remote =3D inode->i_private; + struct trace_remote_iterator *iter =3D NULL; + int cpu =3D RING_BUFFER_ALL_CPUS; + int ret; + + if (!(filp->f_mode & FMODE_READ)) + return 0; + + if (inode->i_cdev) + cpu =3D (long)inode->i_cdev - 1; + + guard(mutex)(&remote->lock); + + iter =3D trace_remote_iter(remote, cpu, TRI_NONCONSUMING); + if (IS_ERR(iter)) + return PTR_ERR(iter); + + ret =3D seq_open(filp, &trace_seq_ops); + if (ret) { + trace_remote_iter_free(iter); + return ret; + } + + if (iter) + trace_remote_iter_read_start(iter); + + ((struct seq_file *)filp->private_data)->private =3D (void *)iter; + + return 0; +} + +static int trace_release(struct inode *inode, struct file *filp) +{ + struct trace_remote_iterator *iter; + + if (!(filp->f_mode & FMODE_READ)) + return 0; + + iter =3D ((struct seq_file *)filp->private_data)->private; + seq_release(inode, filp); + + if (!iter) + return 0; + + guard(mutex)(&iter->remote->lock); + + trace_remote_iter_read_finished(iter); + trace_remote_iter_free(iter); + + return 0; +} + static ssize_t trace_write(struct file *filp, const char __user *ubuf, siz= e_t cnt, loff_t *ppos) { struct inode *inode =3D file_inode(filp); @@ -443,7 +754,11 @@ static ssize_t trace_write(struct file *filp, const ch= ar __user *ubuf, size_t cn } =20 static const struct file_operations trace_fops =3D { + .open =3D trace_open, .write =3D trace_write, + .read =3D seq_read, + .read_iter =3D seq_read_iter, + .release =3D trace_release, }; =20 static int trace_remote_init_tracefs(const char *name, struct trace_remote= *remote) @@ -532,6 +847,7 @@ int trace_remote_register(const char *name, struct trac= e_remote_callbacks *cbs, remote->trace_buffer_size =3D 7 << 10; remote->poll_ms =3D 100; mutex_init(&remote->lock); + init_rwsem(&remote->reader_lock); =20 if (trace_remote_init_tracefs(name, remote)) { kfree(remote); --=20 2.52.0.107.ga0afd4fd5b-goog From nobody Wed Dec 17 06:12:58 2025 Received: from mail-wr1-f73.google.com (mail-wr1-f73.google.com [209.85.221.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 81CE830F929 for ; 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Tue, 02 Dec 2025 01:36:38 -0800 (PST) Date: Tue, 2 Dec 2025 09:36:01 +0000 In-Reply-To: <20251202093623.2337860-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251202093623.2337860-1-vdonnefort@google.com> X-Mailer: git-send-email 2.52.0.107.ga0afd4fd5b-goog Message-ID: <20251202093623.2337860-9-vdonnefort@google.com> Subject: [PATCH v9 08/30] tracing: Add init callback to trace remotes From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-trace-kernel@vger.kernel.org, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, jstultz@google.com, qperret@google.com, will@kernel.org, aneesh.kumar@kernel.org, kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Add a .init call back so the trace remote callers can add entries to the tracefs directory. Signed-off-by: Vincent Donnefort diff --git a/include/linux/trace_remote.h b/include/linux/trace_remote.h index 55754ef78104..15a579633123 100644 --- a/include/linux/trace_remote.h +++ b/include/linux/trace_remote.h @@ -3,11 +3,14 @@ #ifndef _LINUX_TRACE_REMOTE_H #define _LINUX_TRACE_REMOTE_H =20 +#include #include =20 /** * struct trace_remote_callbacks - Callbacks used by Tracefs to control th= e remote * + * @init: Called once the remote has been registered. Allows the + * caller to extend the Tracefs remote directory * @load_trace_buffer: Called before Tracefs accesses the trace buffer fo= r the first * time. Must return a &trace_buffer_desc * (most likely filled with trace_remote_alloc_buffer()) @@ -23,6 +26,7 @@ * new reader-page from the @cpu ring-buffer. */ struct trace_remote_callbacks { + int (*init)(struct dentry *d, void *priv); struct trace_buffer_desc *(*load_trace_buffer)(unsigned long size, void *= priv); void (*unload_trace_buffer)(struct trace_buffer_desc *desc, void *priv); int (*enable_tracing)(bool enable, void *priv); diff --git a/kernel/trace/trace_remote.c b/kernel/trace/trace_remote.c index a744bbf48e88..924e3f3ec6d2 100644 --- a/kernel/trace/trace_remote.c +++ b/kernel/trace/trace_remote.c @@ -837,6 +837,7 @@ static int trace_remote_init_tracefs(const char *name, = struct trace_remote *remo int trace_remote_register(const char *name, struct trace_remote_callbacks = *cbs, void *priv) { struct trace_remote *remote; + int ret; =20 remote =3D kzalloc(sizeof(*remote), GFP_KERNEL); if (!remote) @@ -854,7 +855,11 @@ int trace_remote_register(const char *name, struct tra= ce_remote_callbacks *cbs, return -ENOMEM; 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charset="utf-8" An event is predefined point in the writer code that allows to log data. Following the same scheme as kernel events, add remote events, described to user-space within the events/ tracefs directory found in the corresponding trace remote. Remote events are expected to be described during the trace remote registration. Add also a .enable_event callback for trace_remote to toggle the event logging, if supported. Signed-off-by: Vincent Donnefort diff --git a/include/linux/trace_remote.h b/include/linux/trace_remote.h index 15a579633123..456df837fc6b 100644 --- a/include/linux/trace_remote.h +++ b/include/linux/trace_remote.h @@ -5,6 +5,7 @@ =20 #include #include +#include =20 /** * struct trace_remote_callbacks - Callbacks used by Tracefs to control th= e remote @@ -24,6 +25,8 @@ * @reset: Called on `echo 0 > trace`. It is expected from the * remote to reset all ring-buffer pages. * new reader-page from the @cpu ring-buffer. + * @enable_event: Called on events/event_name/enable. It is expected from + * the remote to allow the writing event @id. */ struct trace_remote_callbacks { int (*init)(struct dentry *d, void *priv); @@ -32,6 +35,7 @@ struct trace_remote_callbacks { int (*enable_tracing)(bool enable, void *priv); int (*swap_reader_page)(unsigned int cpu, void *priv); int (*reset)(unsigned int cpu, void *priv); + int (*enable_event)(unsigned short id, bool enable, void *priv); }; =20 /** @@ -53,7 +57,8 @@ struct trace_remote_callbacks { * * Return: 0 on success, negative error code on failure. */ -int trace_remote_register(const char *name, struct trace_remote_callbacks = *cbs, void *priv); +int trace_remote_register(const char *name, struct trace_remote_callbacks = *cbs, void *priv, + struct remote_event *events, size_t nr_events); =20 /** * trace_remote_alloc_buffer() - Dynamically allocate a trace buffer diff --git a/include/linux/trace_remote_event.h b/include/linux/trace_remot= e_event.h new file mode 100644 index 000000000000..a4449008a075 --- /dev/null +++ b/include/linux/trace_remote_event.h @@ -0,0 +1,23 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#ifndef _LINUX_TRACE_REMOTE_EVENTS_H +#define _LINUX_TRACE_REMOTE_EVENTS_H + +struct trace_remote; +struct trace_event_fields; + +struct remote_event_hdr { + unsigned short id; +}; + +#define REMOTE_EVENT_NAME_MAX 30 +struct remote_event { + char name[REMOTE_EVENT_NAME_MAX]; + unsigned short id; + bool enabled; + struct trace_remote *remote; + struct trace_event_fields *fields; + char *print_fmt; + void (*print)(void *evt, struct trace_seq *seq); +}; +#endif diff --git a/kernel/trace/trace_remote.c b/kernel/trace/trace_remote.c index 924e3f3ec6d2..8527804f2d22 100644 --- a/kernel/trace/trace_remote.c +++ b/kernel/trace/trace_remote.c @@ -33,6 +33,7 @@ struct trace_remote_iterator { struct ring_buffer_iter **rb_iters; struct ring_buffer_iter *rb_iter; }; + struct remote_event_hdr *evt; int cpu; int evt_cpu; loff_t pos; @@ -44,6 +45,10 @@ struct trace_remote { void *priv; struct trace_buffer *trace_buffer; struct trace_buffer_desc *trace_buffer_desc; + struct dentry *dentry; + struct eventfs_inode *eventfs; + struct remote_event *events; + unsigned long nr_events; unsigned long trace_buffer_size; struct ring_buffer_remote rb_remote; struct mutex lock; @@ -168,7 +173,8 @@ static void trace_remote_reset(struct trace_remote *rem= ote, int cpu) static ssize_t tracing_on_write(struct file *filp, const char __user *ubuf, size_t cnt, l= off_t *ppos) { - struct trace_remote *remote =3D filp->private_data; + struct seq_file *seq =3D filp->private_data; + struct trace_remote *remote =3D seq->private; unsigned long val; int ret; =20 @@ -197,7 +203,8 @@ DEFINE_SHOW_STORE_ATTRIBUTE(tracing_on); static ssize_t buffer_size_kb_write(struct file *filp, const char __user *= ubuf, size_t cnt, loff_t *ppos) { - struct trace_remote *remote =3D filp->private_data; + struct seq_file *seq =3D filp->private_data; + struct trace_remote *remote =3D seq->private; unsigned long val; int ret; =20 @@ -484,16 +491,19 @@ __peek_event(struct trace_remote_iterator *iter, int = cpu, u64 *ts, unsigned long static bool trace_remote_iter_read_event(struct trace_remote_iterator *ite= r) { struct trace_buffer *trace_buffer =3D iter->remote->trace_buffer; + struct ring_buffer_event *rb_evt; int cpu =3D iter->cpu; =20 if (cpu !=3D RING_BUFFER_ALL_CPUS) { if (ring_buffer_empty_cpu(trace_buffer, cpu)) return false; =20 - if (!__peek_event(iter, cpu, &iter->ts, &iter->lost_events)) + rb_evt =3D __peek_event(iter, cpu, &iter->ts, &iter->lost_events); + if (!rb_evt) return false; =20 iter->evt_cpu =3D cpu; + iter->evt =3D (struct remote_event_hdr *)ring_buffer_event_data(rb_evt); return true; } =20 @@ -505,7 +515,8 @@ static bool trace_remote_iter_read_event(struct trace_r= emote_iterator *iter) if (ring_buffer_empty_cpu(trace_buffer, cpu)) continue; =20 - if (!__peek_event(iter, cpu, &ts, &lost_events)) + rb_evt =3D __peek_event(iter, cpu, &ts, &lost_events); + if (!rb_evt) continue; =20 if (ts >=3D iter->ts) @@ -513,6 +524,7 @@ static bool trace_remote_iter_read_event(struct trace_r= emote_iterator *iter) =20 iter->ts =3D ts; iter->evt_cpu =3D cpu; + iter->evt =3D (struct remote_event_hdr *)ring_buffer_event_data(rb_evt); iter->lost_events =3D lost_events; } =20 @@ -533,8 +545,11 @@ static void trace_remote_iter_move(struct trace_remote= _iterator *iter) } } =20 +static struct remote_event *trace_remote_find_event(struct trace_remote *r= emote, unsigned short id); + static int trace_remote_iter_print_event(struct trace_remote_iterator *ite= r) { + struct remote_event *evt; unsigned long usecs_rem; u64 ts =3D iter->ts; =20 @@ -548,6 +563,12 @@ static int trace_remote_iter_print_event(struct trace_= remote_iterator *iter) trace_seq_printf(&iter->seq, "[%03d]\t%5llu.%06lu: ", iter->evt_cpu, ts, usecs_rem); =20 + evt =3D trace_remote_find_event(iter->remote, iter->evt->id); + if (!evt) + trace_seq_printf(&iter->seq, "UNKNOWN id=3D%d\n", iter->evt->id); + else + evt->print(iter->evt, &iter->seq); + return trace_seq_has_overflowed(&iter->seq) ? -EOVERFLOW : 0; } =20 @@ -821,6 +842,8 @@ static int trace_remote_init_tracefs(const char *name, = struct trace_remote *remo goto err; } =20 + remote->dentry =3D remote_d; + return 0; =20 err: @@ -834,7 +857,11 @@ static int trace_remote_init_tracefs(const char *name,= struct trace_remote *remo return -ENOMEM; } =20 -int trace_remote_register(const char *name, struct trace_remote_callbacks = *cbs, void *priv) +static int trace_remote_register_events(const char *remote_name, struct tr= ace_remote *remote, + struct remote_event *events, size_t nr_events); + +int trace_remote_register(const char *name, struct trace_remote_callbacks = *cbs, void *priv, + struct remote_event *events, size_t nr_events) { struct trace_remote *remote; int ret; @@ -855,6 +882,13 @@ int trace_remote_register(const char *name, struct tra= ce_remote_callbacks *cbs, return -ENOMEM; } =20 + ret =3D trace_remote_register_events(name, remote, events, nr_events); + if (ret) { + pr_err("Failed to register events for trace remote '%s' (%d)\n", + name, ret); + return ret; + } + ret =3D cbs->init ? cbs->init(remote->dentry, priv) : 0; if (ret) pr_err("Init failed for trace remote '%s' (%d)\n", name, ret); @@ -929,3 +963,220 @@ int trace_remote_alloc_buffer(struct trace_buffer_des= c *desc, size_t desc_size, return ret; } EXPORT_SYMBOL_GPL(trace_remote_alloc_buffer); + +static int +trace_remote_enable_event(struct trace_remote *remote, struct remote_event= *evt, bool enable) +{ + int ret; + + lockdep_assert_held(&remote->lock); + + if (evt->enabled =3D=3D enable) + return 0; + + ret =3D remote->cbs->enable_event(evt->id, enable, remote->priv); + if (ret) + return ret; + + evt->enabled =3D enable; + + return 0; +} + +static int remote_event_enable_show(struct seq_file *s, void *unused) +{ + struct remote_event *evt =3D s->private; + + seq_printf(s, "%d\n", evt->enabled); + + return 0; +} + +static ssize_t remote_event_enable_write(struct file *filp, const char __u= ser *ubuf, + size_t count, loff_t *ppos) +{ + struct seq_file *seq =3D filp->private_data; + struct remote_event *evt =3D seq->private; + struct trace_remote *remote =3D evt->remote; + u8 enable; + int ret; + + ret =3D kstrtou8_from_user(ubuf, count, 10, &enable); + if (ret) + return ret; + + guard(mutex)(&remote->lock); + + ret =3D trace_remote_enable_event(remote, evt, enable); + if (ret) + return ret; + + return count; +} +DEFINE_SHOW_STORE_ATTRIBUTE(remote_event_enable); + +static int remote_event_id_show(struct seq_file *s, void *unused) +{ + struct remote_event *evt =3D s->private; + + seq_printf(s, "%d\n", evt->id); + + return 0; +} +DEFINE_SHOW_ATTRIBUTE(remote_event_id); + +static int remote_event_format_show(struct seq_file *s, void *unused) +{ + size_t offset =3D sizeof(struct remote_event_hdr); + struct remote_event *evt =3D s->private; + struct trace_event_fields *field; + + seq_printf(s, "name: %s\n", evt->name); + seq_printf(s, "ID: %d\n", evt->id); + seq_puts(s, + "format:\n\tfield:unsigned short common_type;\toffset:0;\tsize:2;\tsign= ed:0;\n\n"); + + field =3D &evt->fields[0]; + while (field->name) { + seq_printf(s, "\tfield:%s %s;\toffset:%zu;\tsize:%u;\tsigned:%d;\n", + field->type, field->name, offset, field->size, + field->is_signed); + offset +=3D field->size; + field++; + } + + if (field !=3D &evt->fields[0]) + seq_puts(s, "\n"); + + seq_printf(s, "print fmt: %s\n", evt->print_fmt); + + return 0; +} +DEFINE_SHOW_ATTRIBUTE(remote_event_format); + +static int remote_event_callback(const char *name, umode_t *mode, void **d= ata, + const struct file_operations **fops) +{ + if (!strcmp(name, "enable")) { + *mode =3D TRACEFS_MODE_WRITE; + *fops =3D &remote_event_enable_fops; + return 1; + } + + if (!strcmp(name, "id")) { + *mode =3D TRACEFS_MODE_READ; + *fops =3D &remote_event_id_fops; + return 1; + } + + if (!strcmp(name, "format")) { + *mode =3D TRACEFS_MODE_READ; + *fops =3D &remote_event_format_fops; + return 1; + } + + return 0; +} + +static int trace_remote_init_eventfs(const char *remote_name, struct trace= _remote *remote, + struct remote_event *evt) +{ + struct eventfs_inode *eventfs =3D remote->eventfs; + static struct eventfs_entry entries[] =3D { + { + .name =3D "enable", + .callback =3D remote_event_callback, + }, { + .name =3D "id", + .callback =3D remote_event_callback, + }, { + .name =3D "format", + .callback =3D remote_event_callback, + } + }; + bool eventfs_create =3D false; + + if (!eventfs) { + eventfs =3D eventfs_create_events_dir("events", remote->dentry, NULL, 0,= NULL); + if (IS_ERR(eventfs)) + return PTR_ERR(eventfs); + + /* + * Create similar hierarchy as local events even if a single system is s= upported at + * the moment + */ + eventfs =3D eventfs_create_dir(remote_name, eventfs, NULL, 0, NULL); + if (IS_ERR(eventfs)) + return PTR_ERR(eventfs); + + remote->eventfs =3D eventfs; + eventfs_create =3D true; + } + + eventfs =3D eventfs_create_dir(evt->name, eventfs, entries, ARRAY_SIZE(en= tries), evt); + if (IS_ERR(eventfs)) { + if (eventfs_create) { + eventfs_remove_events_dir(remote->eventfs); + remote->eventfs =3D NULL; + } + return PTR_ERR(eventfs); + } + + return 0; +} + +static int trace_remote_attach_events(struct trace_remote *remote, struct = remote_event *events, + size_t nr_events) +{ + int i; + + for (i =3D 0; i < nr_events; i++) { + struct remote_event *evt =3D &events[i]; + + if (evt->remote) + return -EEXIST; + + evt->remote =3D remote; + + /* We need events to be sorted for efficient lookup */ + if (i && evt->id <=3D events[i - 1].id) + return -EINVAL; + } + + remote->events =3D events; + remote->nr_events =3D nr_events; + + return 0; +} + +static int trace_remote_register_events(const char *remote_name, struct tr= ace_remote *remote, + struct remote_event *events, size_t nr_events) +{ + int i, ret; + + ret =3D trace_remote_attach_events(remote, events, nr_events); + if (ret) + return ret; + + for (i =3D 0; i < nr_events; i++) { + struct remote_event *evt =3D &events[i]; + + ret =3D trace_remote_init_eventfs(remote_name, remote, evt); + if (ret) + pr_warn("Failed to init eventfs for event '%s' (%d)", + evt->name, ret); + } + + return 0; +} + +static int __cmp_events(const void *id, const void *evt) +{ + return (long)id - ((struct remote_event *)evt)->id; +} + +static struct remote_event *trace_remote_find_event(struct trace_remote *r= emote, unsigned short id) +{ + return bsearch((const void *)(unsigned long)id, remote->events, remote->n= r_events, + sizeof(*remote->events), __cmp_events); 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charset="utf-8" Just like for the kernel events directory, add 'enable', 'header_page' and 'header_event' at the root of the trace remote events/ directory. Signed-off-by: Vincent Donnefort diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index cb674a9fc359..9f28e7b3058c 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -604,7 +604,8 @@ int ring_buffer_print_page_header(struct trace_buffer *= buffer, struct trace_seq trace_seq_printf(s, "\tfield: char data;\t" "offset:%u;\tsize:%u;\tsigned:%u;\n", (unsigned int)offsetof(typeof(field), data), - (unsigned int)buffer->subbuf_size, + (unsigned int)(buffer ? buffer->subbuf_size : + PAGE_SIZE - BUF_PAGE_HDR_SIZE), (unsigned int)is_signed_type(char)); =20 return !trace_seq_has_overflowed(s); diff --git a/kernel/trace/trace_remote.c b/kernel/trace/trace_remote.c index 8527804f2d22..e54cc3e75dc5 100644 --- a/kernel/trace/trace_remote.c +++ b/kernel/trace/trace_remote.c @@ -1078,10 +1078,145 @@ static int remote_event_callback(const char *name,= umode_t *mode, void **data, return 0; } =20 +static ssize_t remote_events_dir_enable_write(struct file *filp, const cha= r __user *ubuf, + size_t count, loff_t *ppos) +{ + struct trace_remote *remote =3D file_inode(filp)->i_private; + int i, ret; + u8 enable; + + ret =3D kstrtou8_from_user(ubuf, count, 10, &enable); + if (ret) + return ret; + + guard(mutex)(&remote->lock); + + for (i =3D 0; i < remote->nr_events; i++) { + struct remote_event *evt =3D &remote->events[i]; + + trace_remote_enable_event(remote, evt, enable); + } + + return count; +} + +static ssize_t remote_events_dir_enable_read(struct file *filp, char __use= r *ubuf, size_t cnt, + loff_t *ppos) +{ + struct trace_remote *remote =3D file_inode(filp)->i_private; + const char enabled_char[] =3D {'0', '1', 'X'}; + char enabled_str[] =3D " \n"; + int i, enabled =3D -1; + + guard(mutex)(&remote->lock); + + for (i =3D 0; i < remote->nr_events; i++) { + struct remote_event *evt =3D &remote->events[i]; + + if (enabled =3D=3D -1) { + enabled =3D evt->enabled; + } else if (enabled !=3D evt->enabled) { + enabled =3D 2; + break; + } + } + + enabled_str[0] =3D enabled_char[enabled =3D=3D -1 ? 0 : enabled]; + + return simple_read_from_buffer(ubuf, cnt, ppos, enabled_str, 2); +} + +static const struct file_operations remote_events_dir_enable_fops =3D { + .write =3D remote_events_dir_enable_write, + .read =3D remote_events_dir_enable_read, +}; + +static ssize_t +remote_events_dir_header_page_read(struct file *filp, char __user *ubuf, s= ize_t cnt, loff_t *ppos) +{ + struct trace_seq *s; + int ret; + + s =3D kmalloc(sizeof(*s), GFP_KERNEL); + if (!s) + return -ENOMEM; + + trace_seq_init(s); + + ring_buffer_print_page_header(NULL, s); + ret =3D simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, trace_seq_use= d(s)); + kfree(s); + + return ret; +} + +static const struct file_operations remote_events_dir_header_page_fops =3D= { + .read =3D remote_events_dir_header_page_read, +}; + +static ssize_t +remote_events_dir_header_event_read(struct file *filp, char __user *ubuf, = size_t cnt, loff_t *ppos) +{ + struct trace_seq *s; + int ret; + + s =3D kmalloc(sizeof(*s), GFP_KERNEL); + if (!s) + return -ENOMEM; + + trace_seq_init(s); + + ring_buffer_print_entry_header(s); + ret =3D simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, trace_seq_use= d(s)); + kfree(s); + + return ret; +} + +static const struct file_operations remote_events_dir_header_event_fops = =3D { + .read =3D remote_events_dir_header_event_read, +}; + +static int remote_events_dir_callback(const char *name, umode_t *mode, voi= d **data, + const struct file_operations **fops) +{ + if (!strcmp(name, "enable")) { + *mode =3D TRACEFS_MODE_WRITE; + *fops =3D &remote_events_dir_enable_fops; + return 1; + } + + if (!strcmp(name, "header_page")) { + *mode =3D TRACEFS_MODE_READ; + *fops =3D &remote_events_dir_header_page_fops; + return 1; + } + + if (!strcmp(name, "header_event")) { + *mode =3D TRACEFS_MODE_READ; + *fops =3D &remote_events_dir_header_event_fops; + return 1; + } + + return 0; +} + static int trace_remote_init_eventfs(const char *remote_name, struct trace= _remote *remote, struct remote_event *evt) { struct eventfs_inode *eventfs =3D remote->eventfs; + static struct eventfs_entry dir_entries[] =3D { + { + .name =3D "enable", + .callback =3D remote_events_dir_callback, + }, { + .name =3D "header_page", + .callback =3D remote_events_dir_callback, + }, { + .name =3D "header_event", + .callback =3D remote_events_dir_callback, + } + }; static struct eventfs_entry entries[] =3D { { .name =3D "enable", @@ -1097,7 +1232,8 @@ static int trace_remote_init_eventfs(const char *remo= te_name, struct trace_remot bool eventfs_create =3D false; =20 if (!eventfs) { - eventfs =3D eventfs_create_events_dir("events", remote->dentry, NULL, 0,= NULL); + eventfs =3D eventfs_create_events_dir("events", remote->dentry, dir_entr= ies, + ARRAY_SIZE(dir_entries), remote); if (IS_ERR(eventfs)) return PTR_ERR(eventfs); =20 --=20 2.52.0.107.ga0afd4fd5b-goog From nobody Wed Dec 17 06:12:58 2025 Received: from mail-wm1-f73.google.com (mail-wm1-f73.google.com [209.85.128.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 829C231076B for ; Tue, 2 Dec 2025 09:36:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.73 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764668206; 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Tue, 02 Dec 2025 01:36:41 -0800 (PST) Date: Tue, 2 Dec 2025 09:36:04 +0000 In-Reply-To: <20251202093623.2337860-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251202093623.2337860-1-vdonnefort@google.com> X-Mailer: git-send-email 2.52.0.107.ga0afd4fd5b-goog Message-ID: <20251202093623.2337860-12-vdonnefort@google.com> Subject: [PATCH v9 11/30] tracing: Add helpers to create trace remote events From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-trace-kernel@vger.kernel.org, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, jstultz@google.com, qperret@google.com, will@kernel.org, aneesh.kumar@kernel.org, kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Declaring remote events can be cumbersome let's add a set of macros to simplify developers life. The declaration of a remote event is very similar to kernel's events: REMOTE_EVENT(name, id, RE_STRUCT( re_field(u64 foo) ), RE_PRINTK("foo=3D%llu", __entry->foo) ) Signed-off-by: Vincent Donnefort diff --git a/include/linux/trace_remote_event.h b/include/linux/trace_remot= e_event.h index a4449008a075..c8ae1e1f5e72 100644 --- a/include/linux/trace_remote_event.h +++ b/include/linux/trace_remote_event.h @@ -5,6 +5,7 @@ =20 struct trace_remote; struct trace_event_fields; +struct trace_seq; =20 struct remote_event_hdr { unsigned short id; @@ -20,4 +21,13 @@ struct remote_event { char *print_fmt; void (*print)(void *evt, struct trace_seq *seq); }; + +#define RE_STRUCT(__args...) __args +#define re_field(__type, __field) __type __field; + +#define REMOTE_EVENT_FORMAT(__name, __struct) \ + struct remote_event_format_##__name { \ + struct remote_event_hdr hdr; \ + __struct \ + } #endif diff --git a/include/trace/define_remote_events.h b/include/trace/define_re= mote_events.h new file mode 100644 index 000000000000..03c9f5515c5a --- /dev/null +++ b/include/trace/define_remote_events.h @@ -0,0 +1,73 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#include +#include +#include +#include + +#define REMOTE_EVENT_INCLUDE(__file) __stringify(../../__file) + +#ifdef REMOTE_EVENT_SECTION +# define __REMOTE_EVENT_SECTION(__name) __used __section(REMOTE_EVENT_SECT= ION"."#__name) +#else +# define __REMOTE_EVENT_SECTION(__name) +#endif + +#define __REMOTE_PRINTK_COUNT_ARGS(_0, _1, _2, _n, __args...) _n +#define REMOTE_PRINTK_COUNT_ARGS(__args...) __REMOTE_PRINTK_COUNT_ARGS(, #= #__args, 2, 1, 0) + +#define __remote_printk0() \ + trace_seq_putc(seq, '\n') + +#define __remote_printk1(__fmt) \ + trace_seq_puts(seq, " " __fmt "\n") \ + +#define __remote_printk2(__fmt, __args...) \ +do { \ + trace_seq_putc(seq, ' '); \ + trace_seq_printf(seq, __fmt, __args); \ + trace_seq_putc(seq, '\n'); \ +} while (0) + +/* Apply the appropriate trace_seq sequence according to the number of arg= uments */ +#define remote_printk(__args...) \ + CONCATENATE(__remote_printk, REMOTE_PRINTK_COUNT_ARGS(__args))(__args) + +#define RE_PRINTK(__args...) __args + +#define REMOTE_EVENT(__name, __id, __struct, __printk) \ + REMOTE_EVENT_FORMAT(__name, __struct); \ + static void remote_event_print_##__name(void *evt, struct trace_seq *seq)= \ + { \ + struct remote_event_format_##__name __maybe_unused *__entry =3D evt; \ + trace_seq_puts(seq, #__name); \ + remote_printk(__printk); \ + } +#include REMOTE_EVENT_INCLUDE(REMOTE_EVENT_INCLUDE_FILE) + +#undef REMOTE_EVENT +#undef RE_PRINTK +#undef re_field +#define re_field(__type, __field) \ + { \ + .type =3D #__type, .name =3D #__field, \ + .size =3D sizeof(__type), .align =3D __alignof__(__type), \ + .is_signed =3D is_signed_type(__type), \ + }, +#define __entry REC +#define RE_PRINTK(__fmt, __args...) 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Tue, 02 Dec 2025 01:36:43 -0800 (PST) Date: Tue, 2 Dec 2025 09:36:05 +0000 In-Reply-To: <20251202093623.2337860-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251202093623.2337860-1-vdonnefort@google.com> X-Mailer: git-send-email 2.52.0.107.ga0afd4fd5b-goog Message-ID: <20251202093623.2337860-13-vdonnefort@google.com> Subject: [PATCH v9 12/30] ring-buffer: Export buffer_data_page and macros From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-trace-kernel@vger.kernel.org, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, jstultz@google.com, qperret@google.com, will@kernel.org, aneesh.kumar@kernel.org, kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" In preparation for allowing the writing of ring-buffer compliant pages outside of ring_buffer.c, move buffer_data_page and timestamps encoding macros into the publicly available ring_buffer_types.h. Signed-off-by: Vincent Donnefort diff --git a/include/linux/ring_buffer_types.h b/include/linux/ring_buffer_= types.h new file mode 100644 index 000000000000..54577021a49d --- /dev/null +++ b/include/linux/ring_buffer_types.h @@ -0,0 +1,41 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_RING_BUFFER_TYPES_H +#define _LINUX_RING_BUFFER_TYPES_H + +#include + +#define TS_SHIFT 27 +#define TS_MASK ((1ULL << TS_SHIFT) - 1) +#define TS_DELTA_TEST (~TS_MASK) + +/* + * We need to fit the time_stamp delta into 27 bits. + */ +static inline bool test_time_stamp(u64 delta) +{ + return !!(delta & TS_DELTA_TEST); +} + +#define BUF_PAGE_HDR_SIZE offsetof(struct buffer_data_page, data) + +#define RB_EVNT_HDR_SIZE (offsetof(struct ring_buffer_event, array)) +#define RB_ALIGNMENT 4U +#define RB_MAX_SMALL_DATA (RB_ALIGNMENT * RINGBUF_TYPE_DATA_TYPE_LEN_MAX) +#define RB_EVNT_MIN_SIZE 8U /* two 32bit words */ + +#ifndef CONFIG_HAVE_64BIT_ALIGNED_ACCESS +# define RB_FORCE_8BYTE_ALIGNMENT 0 +# define RB_ARCH_ALIGNMENT RB_ALIGNMENT +#else +# define RB_FORCE_8BYTE_ALIGNMENT 1 +# define RB_ARCH_ALIGNMENT 8U +#endif + +#define RB_ALIGN_DATA __aligned(RB_ARCH_ALIGNMENT) + +struct buffer_data_page { + u64 time_stamp; /* page time stamp */ + local_t commit; /* write committed index */ + unsigned char data[] RB_ALIGN_DATA; /* data of buffer page */ +}; +#endif diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 9f28e7b3058c..7a1a8d5f3a25 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -4,6 +4,7 @@ * * Copyright (C) 2008 Steven Rostedt */ +#include #include #include #include @@ -156,23 +157,6 @@ int ring_buffer_print_entry_header(struct trace_seq *s) /* Used for individual buffers (after the counter) */ #define RB_BUFFER_OFF (1 << 20) =20 -#define BUF_PAGE_HDR_SIZE offsetof(struct buffer_data_page, data) - -#define RB_EVNT_HDR_SIZE (offsetof(struct ring_buffer_event, array)) -#define RB_ALIGNMENT 4U -#define RB_MAX_SMALL_DATA (RB_ALIGNMENT * RINGBUF_TYPE_DATA_TYPE_LEN_MAX) -#define RB_EVNT_MIN_SIZE 8U /* two 32bit words */ - -#ifndef CONFIG_HAVE_64BIT_ALIGNED_ACCESS -# define RB_FORCE_8BYTE_ALIGNMENT 0 -# define RB_ARCH_ALIGNMENT RB_ALIGNMENT -#else -# define RB_FORCE_8BYTE_ALIGNMENT 1 -# define RB_ARCH_ALIGNMENT 8U -#endif - -#define RB_ALIGN_DATA __aligned(RB_ARCH_ALIGNMENT) - /* define RINGBUF_TYPE_DATA for 'case RINGBUF_TYPE_DATA:' */ #define RINGBUF_TYPE_DATA 0 ... RINGBUF_TYPE_DATA_TYPE_LEN_MAX =20 @@ -315,10 +299,6 @@ EXPORT_SYMBOL_GPL(ring_buffer_event_data); #define for_each_online_buffer_cpu(buffer, cpu) \ for_each_cpu_and(cpu, buffer->cpumask, cpu_online_mask) =20 -#define TS_SHIFT 27 -#define TS_MASK ((1ULL << TS_SHIFT) - 1) -#define TS_DELTA_TEST (~TS_MASK) - static u64 rb_event_time_stamp(struct ring_buffer_event *event) { u64 ts; @@ -337,12 +317,6 @@ static u64 rb_event_time_stamp(struct ring_buffer_even= t *event) =20 #define RB_MISSED_MASK (3 << 30) =20 -struct buffer_data_page { - u64 time_stamp; /* page time stamp */ - local_t commit; /* write committed index */ - unsigned char data[] RB_ALIGN_DATA; /* data of buffer page */ -}; - struct buffer_data_read_page { unsigned order; /* order of the page */ struct buffer_data_page *data; /* actual data, stored in this page */ @@ -401,14 +375,6 @@ static void free_buffer_page(struct buffer_page *bpage) kfree(bpage); } =20 -/* - * We need to fit the time_stamp delta into 27 bits. - */ -static inline bool test_time_stamp(u64 delta) -{ - return !!(delta & TS_DELTA_TEST); 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charset="utf-8" Add a simple implementation of the kernel ring-buffer. This intends to be used later by ring-buffer remotes such as the pKVM hypervisor, hence the need for a cut down version (write only) without any dependency. Signed-off-by: Vincent Donnefort diff --git a/include/linux/simple_ring_buffer.h b/include/linux/simple_ring= _buffer.h new file mode 100644 index 000000000000..f324df2f875b --- /dev/null +++ b/include/linux/simple_ring_buffer.h @@ -0,0 +1,113 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_SIMPLE_RING_BUFFER_H +#define _LINUX_SIMPLE_RING_BUFFER_H + +#include +#include +#include +#include + +/* + * Ideally those struct would stay private but the caller needs to know + * the allocation size for simple_ring_buffer_init(). + */ +struct simple_buffer_page { + struct list_head link; + struct buffer_data_page *page; + u64 entries; + u32 write; + u32 id; +}; + +struct simple_rb_per_cpu { + struct simple_buffer_page *tail_page; + struct simple_buffer_page *reader_page; + struct simple_buffer_page *head_page; + struct simple_buffer_page *bpages; + struct trace_buffer_meta *meta; + u32 nr_pages; + +#define SIMPLE_RB_UNAVAILABLE 0 +#define SIMPLE_RB_READY 1 +#define SIMPLE_RB_WRITING 2 + u32 status; + + u64 last_overrun; + u64 write_stamp; + + struct simple_rb_cbs *cbs; +}; + +/** + * simple_ring_buffer_init - Init @cpu_buffer based on @desc + * + * @cpu_buffer: A simple_rb_per_cpu buffer to init, allocated by the calle= r. + * @bpages: Array of simple_buffer_pages, with as many elements as @desc->= nr_page_va + * @desc: A ring_buffer_desc + * + * Returns: 0 on success or -EINVAL if the content of @desc is invalid + */ +int simple_ring_buffer_init(struct simple_rb_per_cpu *cpu_buffer, struct s= imple_buffer_page *bpages, + const struct ring_buffer_desc *desc); + +/** + * simple_ring_buffer_unload - Prepare @cpu_buffer for deletion + * + * @cpu_buffer: A simple_rb_per_cpu that will be deleted. + */ +void simple_ring_buffer_unload(struct simple_rb_per_cpu *cpu_buffer); + +/** + * simple_ring_buffer_reserve - Reserve an entry in @cpu_buffer + * + * @cpu_buffer: A simple_rb_per_cpu + * @length: Size of the entry in bytes + * @timestamp: Timestamp of the entry + * + * Returns the address of the entry where to write data or NULL + */ +void *simple_ring_buffer_reserve(struct simple_rb_per_cpu *cpu_buffer, uns= igned long length, + u64 timestamp); + +/** + * simple_ring_buffer_commit - Commit the entry reserved with simple_ring_= buffer_reserve() + * + * @cpu_buffer: The simple_rb_per_cpu where the entry has been reserved + */ +void simple_ring_buffer_commit(struct simple_rb_per_cpu *cpu_buffer); + +/** + * simple_ring_buffer_enable_tracing - Enable or disable writing to @cpu_b= uffer + * + * @cpu_buffer: A simple_rb_per_cpu + * @enable: True to enable tracing, False to disable it + * + * Returns 0 on success or -ENODEV if @cpu_buffer was unloaded + */ +int simple_ring_buffer_enable_tracing(struct simple_rb_per_cpu *cpu_buffer= , bool enable); + +/** + * simple_ring_buffer_reset - Reset @cpu_buffer + * + * @cpu_buffer: A simple_rb_per_cpu + * + * This will not clear the content of the data, only reset counters and po= inters + * + * Returns 0 on success or -ENODEV if @cpu_buffer was unloaded. + */ +int simple_ring_buffer_reset(struct simple_rb_per_cpu *cpu_buffer); + +/** + * simple_ring_buffer_swap_reader_page - Swap ring-buffer head with the re= ader + * + * This function enables consuming reading. It ensures the current head pa= ge will not be overwritten + * and can be safely read. + * + * @cpu_buffer: A simple_rb_per_cpu + * + * Returns 0 on success, -ENODEV if @cpu_buffer was unloaded or -EBUSY if = we failed to catch the + * head page. + */ +int simple_ring_buffer_swap_reader_page(struct simple_rb_per_cpu *cpu_buff= er); + +#endif diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index 99af56d39eaf..918afcc1fcaf 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -1241,4 +1241,7 @@ source "kernel/trace/rv/Kconfig" config TRACE_REMOTE bool =20 +config SIMPLE_RING_BUFFER + bool + endif # FTRACE diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile index 6dab341acc46..03d7d80a9436 100644 --- a/kernel/trace/Makefile +++ b/kernel/trace/Makefile @@ -111,4 +111,5 @@ obj-$(CONFIG_TRACEPOINT_BENCHMARK) +=3D trace_benchmark= .o obj-$(CONFIG_RV) +=3D rv/ =20 obj-$(CONFIG_TRACE_REMOTE) +=3D trace_remote.o +obj-$(CONFIG_SIMPLE_RING_BUFFER) +=3D simple_ring_buffer.o libftrace-y :=3D ftrace.o diff --git a/kernel/trace/simple_ring_buffer.c b/kernel/trace/simple_ring_b= uffer.c new file mode 100644 index 000000000000..1d1f40c8c6d8 --- /dev/null +++ b/kernel/trace/simple_ring_buffer.c @@ -0,0 +1,415 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2025 - Google LLC + * Author: Vincent Donnefort + */ + +#include +#include + +#include +#include + +enum simple_rb_link_type { + SIMPLE_RB_LINK_NORMAL =3D 0, + SIMPLE_RB_LINK_HEAD =3D 1, + SIMPLE_RB_LINK_HEAD_MOVING +}; + +#define SIMPLE_RB_LINK_MASK ~(SIMPLE_RB_LINK_HEAD | SIMPLE_RB_LINK_HEAD_MO= VING) + +static void simple_bpage_set_head_link(struct simple_buffer_page *bpage) +{ + unsigned long link =3D (unsigned long)bpage->link.next; + + link &=3D SIMPLE_RB_LINK_MASK; + link |=3D SIMPLE_RB_LINK_HEAD; + + /* + * Paired with simple_rb_find_head() to order access between the head + * link and overrun. It ensures we always report an up-to-date value + * after swapping the reader page. + */ + smp_store_release(&bpage->link.next, (struct list_head *)link); +} + +static bool simple_bpage_unset_head_link(struct simple_buffer_page *bpage, + struct simple_buffer_page *dst, + enum simple_rb_link_type new_type) +{ + unsigned long *link =3D (unsigned long *)(&bpage->link.next); + unsigned long old =3D (*link & SIMPLE_RB_LINK_MASK) | SIMPLE_RB_LINK_HEAD; + unsigned long new =3D (unsigned long)(&dst->link) | new_type; + + return try_cmpxchg(link, &old, new); +} + +static void simple_bpage_set_normal_link(struct simple_buffer_page *bpage) +{ + unsigned long link =3D (unsigned long)bpage->link.next; + + WRITE_ONCE(bpage->link.next, (struct list_head *)(link & SIMPLE_RB_LINK_M= ASK)); +} + +static struct simple_buffer_page *simple_bpage_from_link(struct list_head = *link) +{ + unsigned long ptr =3D (unsigned long)link & SIMPLE_RB_LINK_MASK; + + return container_of((struct list_head *)ptr, struct simple_buffer_page, l= ink); +} + +static struct simple_buffer_page *simple_bpage_next_page(struct simple_buf= fer_page *bpage) +{ + return simple_bpage_from_link(bpage->link.next); +} + +static void simple_bpage_reset(struct simple_buffer_page *bpage) +{ + bpage->write =3D 0; + bpage->entries =3D 0; + + local_set(&bpage->page->commit, 0); +} + +static void simple_bpage_init(struct simple_buffer_page *bpage, unsigned l= ong page) +{ + INIT_LIST_HEAD(&bpage->link); + bpage->page =3D (struct buffer_data_page *)page; + + simple_bpage_reset(bpage); +} + +#define simple_rb_meta_inc(__meta, __inc) \ + WRITE_ONCE((__meta), (__meta + __inc)) + +static bool simple_rb_loaded(struct simple_rb_per_cpu *cpu_buffer) +{ + return !!cpu_buffer->bpages; +} + +static int simple_rb_find_head(struct simple_rb_per_cpu *cpu_buffer) +{ + int retry =3D cpu_buffer->nr_pages * 2; + struct simple_buffer_page *head; + + head =3D cpu_buffer->head_page; + + while (retry--) { + unsigned long link; + +spin: + /* See smp_store_release in simple_bpage_set_head_link() */ + link =3D (unsigned long)smp_load_acquire(&head->link.prev->next); + + switch (link & ~SIMPLE_RB_LINK_MASK) { + /* Found the head */ + case SIMPLE_RB_LINK_HEAD: + cpu_buffer->head_page =3D head; + return 0; + /* The writer caught the head, we can spin, that won't be long */ + case SIMPLE_RB_LINK_HEAD_MOVING: + goto spin; + } + + head =3D simple_bpage_next_page(head); + } + + return -EBUSY; +} + +int simple_ring_buffer_swap_reader_page(struct simple_rb_per_cpu *cpu_buff= er) +{ + struct simple_buffer_page *last, *head, *reader; + unsigned long overrun; + int retry =3D 8; + int ret; + + if (!simple_rb_loaded(cpu_buffer)) + return -ENODEV; + + reader =3D cpu_buffer->reader_page; + + do { + /* Run after the writer to find the head */ + ret =3D simple_rb_find_head(cpu_buffer); + if (ret) + return ret; + + head =3D cpu_buffer->head_page; + + /* Connect the reader page around the header page */ + reader->link.next =3D head->link.next; + reader->link.prev =3D head->link.prev; + + /* The last page before the head */ + last =3D simple_bpage_from_link(head->link.prev); + + /* The reader page points to the new header page */ + simple_bpage_set_head_link(reader); + + overrun =3D cpu_buffer->meta->overrun; + } while (!simple_bpage_unset_head_link(last, reader, SIMPLE_RB_LINK_NORMA= L) && retry--); + + if (!retry) + return -EINVAL; + + cpu_buffer->head_page =3D simple_bpage_from_link(reader->link.next); + cpu_buffer->head_page->link.prev =3D &reader->link; + cpu_buffer->reader_page =3D head; + cpu_buffer->meta->reader.lost_events =3D overrun - cpu_buffer->last_overr= un; + cpu_buffer->meta->reader.id =3D cpu_buffer->reader_page->id; + cpu_buffer->last_overrun =3D overrun; + + return 0; +} +EXPORT_SYMBOL_GPL(simple_ring_buffer_swap_reader_page); + +static struct simple_buffer_page *simple_rb_move_tail(struct simple_rb_per= _cpu *cpu_buffer) +{ + struct simple_buffer_page *tail, *new_tail; + + tail =3D cpu_buffer->tail_page; + new_tail =3D simple_bpage_next_page(tail); + + if (simple_bpage_unset_head_link(tail, new_tail, SIMPLE_RB_LINK_HEAD_MOVI= NG)) { + /* + * Oh no! we've caught the head. There is none anymore and + * swap_reader will spin until we set the new one. Overrun must + * be written first, to make sure we report the correct number + * of lost events. + */ + simple_rb_meta_inc(cpu_buffer->meta->overrun, new_tail->entries); + simple_rb_meta_inc(cpu_buffer->meta->pages_lost, 1); + + simple_bpage_set_head_link(new_tail); + simple_bpage_set_normal_link(tail); + } + + simple_bpage_reset(new_tail); + cpu_buffer->tail_page =3D new_tail; + + simple_rb_meta_inc(cpu_buffer->meta->pages_touched, 1); + + return new_tail; +} + +static unsigned long rb_event_size(unsigned long length) +{ + struct ring_buffer_event *event; + + return length + RB_EVNT_HDR_SIZE + sizeof(event->array[0]); +} + +static struct ring_buffer_event * +rb_event_add_ts_extend(struct ring_buffer_event *event, u64 delta) +{ + event->type_len =3D RINGBUF_TYPE_TIME_EXTEND; + event->time_delta =3D delta & TS_MASK; + event->array[0] =3D delta >> TS_SHIFT; + + return (struct ring_buffer_event *)((unsigned long)event + 8); +} + +static struct ring_buffer_event * +simple_rb_reserve_next(struct simple_rb_per_cpu *cpu_buffer, unsigned long= length, u64 timestamp) +{ + unsigned long ts_ext_size =3D 0, event_size =3D rb_event_size(length); + struct simple_buffer_page *tail =3D cpu_buffer->tail_page; + struct ring_buffer_event *event; + u32 write, prev_write; + u64 time_delta; + + time_delta =3D timestamp - cpu_buffer->write_stamp; + + if (test_time_stamp(time_delta)) + ts_ext_size =3D 8; + + prev_write =3D tail->write; + write =3D prev_write + event_size + ts_ext_size; + + if (unlikely(write > (PAGE_SIZE - BUF_PAGE_HDR_SIZE))) + tail =3D simple_rb_move_tail(cpu_buffer); + + if (!tail->entries) { + tail->page->time_stamp =3D timestamp; + time_delta =3D 0; + ts_ext_size =3D 0; + write =3D event_size; + prev_write =3D 0; + } + + tail->write =3D write; + tail->entries++; + + cpu_buffer->write_stamp =3D timestamp; + + event =3D (struct ring_buffer_event *)(tail->page->data + prev_write); + if (ts_ext_size) { + event =3D rb_event_add_ts_extend(event, time_delta); + time_delta =3D 0; + } + + event->type_len =3D 0; + event->time_delta =3D time_delta; + event->array[0] =3D event_size - RB_EVNT_HDR_SIZE; + + return event; +} + +void *simple_ring_buffer_reserve(struct simple_rb_per_cpu *cpu_buffer, uns= igned long length, + u64 timestamp) +{ + struct ring_buffer_event *rb_event; + + if (cmpxchg(&cpu_buffer->status, SIMPLE_RB_READY, SIMPLE_RB_WRITING) !=3D= SIMPLE_RB_READY) + return NULL; + + rb_event =3D simple_rb_reserve_next(cpu_buffer, length, timestamp); + + return &rb_event->array[1]; +} +EXPORT_SYMBOL_GPL(simple_ring_buffer_reserve); + +void simple_ring_buffer_commit(struct simple_rb_per_cpu *cpu_buffer) +{ + local_set(&cpu_buffer->tail_page->page->commit, + cpu_buffer->tail_page->write); + simple_rb_meta_inc(cpu_buffer->meta->entries, 1); + + /* + * Paired with simple_rb_enable_tracing() to ensure data is + * written to the ring-buffer before teardown. + */ + smp_store_release(&cpu_buffer->status, SIMPLE_RB_READY); +} +EXPORT_SYMBOL_GPL(simple_ring_buffer_commit); + +static u32 simple_rb_enable_tracing(struct simple_rb_per_cpu *cpu_buffer, = bool enable) +{ + u32 prev_status; + + if (enable) + return cmpxchg(&cpu_buffer->status, SIMPLE_RB_UNAVAILABLE, SIMPLE_RB_REA= DY); + + /* Wait for the buffer to be released */ + do { + prev_status =3D cmpxchg_acquire(&cpu_buffer->status, + SIMPLE_RB_READY, + SIMPLE_RB_UNAVAILABLE); + } while (prev_status =3D=3D SIMPLE_RB_WRITING); + + return prev_status; +} + +int simple_ring_buffer_reset(struct simple_rb_per_cpu *cpu_buffer) +{ + struct simple_buffer_page *bpage; + u32 prev_status; + int ret; + + if (!simple_rb_loaded(cpu_buffer)) + return -ENODEV; + + prev_status =3D simple_rb_enable_tracing(cpu_buffer, false); + + ret =3D simple_rb_find_head(cpu_buffer); + if (ret) + return ret; + + bpage =3D cpu_buffer->tail_page =3D cpu_buffer->head_page; + do { + simple_bpage_reset(bpage); + bpage =3D simple_bpage_next_page(bpage); + } while (bpage !=3D cpu_buffer->head_page); + + simple_bpage_reset(cpu_buffer->reader_page); + + cpu_buffer->last_overrun =3D 0; + cpu_buffer->write_stamp =3D 0; + + cpu_buffer->meta->reader.read =3D 0; + cpu_buffer->meta->reader.lost_events =3D 0; + cpu_buffer->meta->entries =3D 0; + cpu_buffer->meta->overrun =3D 0; + cpu_buffer->meta->read =3D 0; + cpu_buffer->meta->pages_lost =3D 0; + cpu_buffer->meta->pages_touched =3D 0; + + if (prev_status =3D=3D SIMPLE_RB_READY) + simple_rb_enable_tracing(cpu_buffer, true); + + return 0; +} +EXPORT_SYMBOL_GPL(simple_ring_buffer_reset); + +int simple_ring_buffer_init(struct simple_rb_per_cpu *cpu_buffer, struct s= imple_buffer_page *bpages, + const struct ring_buffer_desc *desc) +{ + struct simple_buffer_page *bpage =3D bpages; + int i; + + /* At least 1 reader page and two pages in the ring-buffer */ + if (desc->nr_page_va < 3) + return -EINVAL; + + memset(cpu_buffer, 0, sizeof(*cpu_buffer)); + + cpu_buffer->bpages =3D bpages; + + cpu_buffer->meta =3D (void *)desc->meta_va; + memset(cpu_buffer->meta, 0, sizeof(*cpu_buffer->meta)); + cpu_buffer->meta->meta_page_size =3D PAGE_SIZE; + cpu_buffer->meta->nr_subbufs =3D cpu_buffer->nr_pages; + + /* The reader page is not part of the ring initially */ + simple_bpage_init(bpage, desc->page_va[0]); + bpage->id =3D 0; + + cpu_buffer->nr_pages =3D 1; + + cpu_buffer->reader_page =3D bpage; + cpu_buffer->tail_page =3D bpage + 1; + cpu_buffer->head_page =3D bpage + 1; + + for (i =3D 1; i < desc->nr_page_va; i++) { + simple_bpage_init(++bpage, desc->page_va[i]); 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Tue, 02 Dec 2025 01:36:44 -0800 (PST) Date: Tue, 2 Dec 2025 09:36:07 +0000 In-Reply-To: <20251202093623.2337860-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251202093623.2337860-1-vdonnefort@google.com> X-Mailer: git-send-email 2.52.0.107.ga0afd4fd5b-goog Message-ID: <20251202093623.2337860-15-vdonnefort@google.com> Subject: [PATCH v9 14/30] tracing: Add a trace remote module for testing From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-trace-kernel@vger.kernel.org, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, jstultz@google.com, qperret@google.com, will@kernel.org, aneesh.kumar@kernel.org, kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Add a module to help testing the tracefs support for trace remotes. This module: * Use simple_ring_buffer to write into a ring-buffer. * Declare a single "selftest" event that can be triggered from user-space. * Register a "test" trace remote. This is intended to be used by trace remote selftests. Signed-off-by: Vincent Donnefort diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c index 0c023941a316..aa305be834f9 100644 --- a/fs/tracefs/inode.c +++ b/fs/tracefs/inode.c @@ -665,6 +665,7 @@ struct dentry *tracefs_create_file(const char *name, um= ode_t mode, fsnotify_create(d_inode(dentry->d_parent), dentry); return tracefs_end_creating(dentry); } +EXPORT_SYMBOL_GPL(tracefs_create_file); =20 static struct dentry *__create_dir(const char *name, struct dentry *parent, const struct inode_operations *ops) diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index 918afcc1fcaf..52131d89993c 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -1244,4 +1244,12 @@ config TRACE_REMOTE config SIMPLE_RING_BUFFER bool =20 +config TRACE_REMOTE_TEST + tristate "Test module for remote tracing" + select TRACE_REMOTE + select SIMPLE_RING_BUFFER + help + This trace remote includes a ring-buffer writer implementation using + "simple_ring_buffer". This is solely intending for testing. + endif # FTRACE diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile index 03d7d80a9436..53534447e70b 100644 --- a/kernel/trace/Makefile +++ b/kernel/trace/Makefile @@ -112,4 +112,6 @@ obj-$(CONFIG_RV) +=3D rv/ =20 obj-$(CONFIG_TRACE_REMOTE) +=3D trace_remote.o obj-$(CONFIG_SIMPLE_RING_BUFFER) +=3D simple_ring_buffer.o +obj-$(CONFIG_TRACE_REMOTE_TEST) +=3D remote_test.o + libftrace-y :=3D ftrace.o diff --git a/kernel/trace/remote_test.c b/kernel/trace/remote_test.c new file mode 100644 index 000000000000..059127489c99 --- /dev/null +++ b/kernel/trace/remote_test.c @@ -0,0 +1,259 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2025 - Google LLC + * Author: Vincent Donnefort + */ + +#include +#include +#include +#include +#include + +#define REMOTE_EVENT_INCLUDE_FILE kernel/trace/remote_test_events.h +#include + +static DEFINE_PER_CPU(struct simple_rb_per_cpu *, simple_rbs); +static struct trace_buffer_desc *remote_test_buffer_desc; + +/* + * The trace_remote lock already serializes accesses from the trace_remote= _callbacks. + * However write_event can still race with load/unload. + */ +static DEFINE_MUTEX(simple_rbs_lock); + +static int remote_test_load_simple_rb(int cpu, struct ring_buffer_desc *rb= _desc) +{ + struct simple_rb_per_cpu *cpu_buffer; + struct simple_buffer_page *bpages; + int ret =3D -ENOMEM; + + cpu_buffer =3D kmalloc(sizeof(*cpu_buffer), GFP_KERNEL); + if (!cpu_buffer) + return ret; + + bpages =3D kmalloc_array(rb_desc->nr_page_va, sizeof(*bpages), GFP_KERNEL= ); + if (!bpages) + goto err_free_cpu_buffer; + + ret =3D simple_ring_buffer_init(cpu_buffer, bpages, rb_desc); + if (ret) + goto err_free_bpages; + + scoped_guard(mutex, &simple_rbs_lock) + *per_cpu_ptr(&simple_rbs, cpu) =3D cpu_buffer; + + return 0; + +err_free_bpages: + kfree(bpages); + +err_free_cpu_buffer: + kfree(cpu_buffer); + + return ret; +} + +static void remote_test_unload_simple_rb(int cpu) +{ + struct simple_rb_per_cpu *cpu_buffer =3D *per_cpu_ptr(&simple_rbs, cpu); + struct simple_buffer_page *bpages; + + if (!cpu_buffer) + return; + + guard(mutex)(&simple_rbs_lock); + + bpages =3D cpu_buffer->bpages; + simple_ring_buffer_unload(cpu_buffer); + kfree(bpages); + kfree(cpu_buffer); + *per_cpu_ptr(&simple_rbs, cpu) =3D NULL; +} + +static struct trace_buffer_desc *remote_test_load(unsigned long size, void= *unused) +{ + struct ring_buffer_desc *rb_desc; + struct trace_buffer_desc *desc; + size_t desc_size; + int cpu, ret; + + if (WARN_ON(remote_test_buffer_desc)) + return ERR_PTR(-EINVAL); + + desc_size =3D trace_buffer_desc_size(size, num_possible_cpus()); + if (desc_size =3D=3D SIZE_MAX) { + ret =3D -E2BIG; + goto err_unlock_cpus; + } + + desc =3D kmalloc(desc_size, GFP_KERNEL); + if (!desc) { + ret =3D -ENOMEM; + goto err_unlock_cpus; + } + + ret =3D trace_remote_alloc_buffer(desc, desc_size, size, cpu_possible_mas= k); + if (ret) + goto err_free_desc; + + for_each_ring_buffer_desc(rb_desc, cpu, desc) { + ret =3D remote_test_load_simple_rb(rb_desc->cpu, rb_desc); + if (ret) + goto err; + } + + remote_test_buffer_desc =3D desc; + + return remote_test_buffer_desc; + +err: + for_each_ring_buffer_desc(rb_desc, cpu, remote_test_buffer_desc) + remote_test_unload_simple_rb(rb_desc->cpu); + trace_remote_free_buffer(remote_test_buffer_desc); + +err_free_desc: + kfree(desc); + +err_unlock_cpus: + cpus_read_unlock(); + + return ERR_PTR(ret); +} + +static void remote_test_unload(struct trace_buffer_desc *desc, void *unuse= d) +{ + struct ring_buffer_desc *rb_desc; + int cpu; + + if (WARN_ON(desc !=3D remote_test_buffer_desc)) + return; + + for_each_ring_buffer_desc(rb_desc, cpu, desc) + remote_test_unload_simple_rb(rb_desc->cpu); + + remote_test_buffer_desc =3D NULL; + trace_remote_free_buffer(desc); + kfree(desc); +} + +static int remote_test_enable_tracing(bool enable, void *unused) +{ + struct ring_buffer_desc *rb_desc; + int cpu; + + if (!remote_test_buffer_desc) + return -ENODEV; + + for_each_ring_buffer_desc(rb_desc, cpu, remote_test_buffer_desc) + WARN_ON(simple_ring_buffer_enable_tracing(*per_cpu_ptr(&simple_rbs, rb_d= esc->cpu), + enable)); + return 0; +} + +static int remote_test_swap_reader_page(unsigned int cpu, void *unused) +{ + struct simple_rb_per_cpu *cpu_buffer; + + if (cpu >=3D NR_CPUS) + return -EINVAL; + + cpu_buffer =3D *per_cpu_ptr(&simple_rbs, cpu); + if (!cpu_buffer) + return -EINVAL; + + return simple_ring_buffer_swap_reader_page(cpu_buffer); +} + +static int remote_test_reset(unsigned int cpu, void *unused) +{ + struct simple_rb_per_cpu *cpu_buffer; + + if (cpu >=3D NR_CPUS) + return -EINVAL; + + cpu_buffer =3D *per_cpu_ptr(&simple_rbs, cpu); + if (!cpu_buffer) + return -EINVAL; + + return simple_ring_buffer_reset(cpu_buffer); +} + +static int remote_test_enable_event(unsigned short id, bool enable, void *= unused) +{ + if (id !=3D REMOTE_TEST_EVENT_ID) + return -EINVAL; + + /* + * Let's just use the struct remote_event enabled field that is turned on= and off by + * trace_remote. This is a bit racy but good enough for a simple test mod= ule. + */ + return 0; +} + +static ssize_t +write_event_write(struct file *filp, const char __user *ubuf, size_t cnt, = loff_t *pos) +{ + struct remote_event_format_selftest *evt_test; + struct simple_rb_per_cpu *cpu_buffer; + unsigned long val; + int ret; + + ret =3D kstrtoul_from_user(ubuf, cnt, 10, &val); + if (ret) + return ret; + + guard(mutex)(&simple_rbs_lock); + + if (!remote_event_selftest.enabled) + return -ENODEV; + + cpu_buffer =3D *this_cpu_ptr(&simple_rbs); + if (!cpu_buffer) + return -ENODEV; + + evt_test =3D simple_ring_buffer_reserve(cpu_buffer, + sizeof(struct remote_event_format_selftest), + trace_clock_global()); + if (!evt_test) + return -ENODEV; + + evt_test->hdr.id =3D REMOTE_TEST_EVENT_ID; + evt_test->id =3D val; + + simple_ring_buffer_commit(cpu_buffer); + + return cnt; +} + +static const struct file_operations write_event_fops =3D { + .write =3D write_event_write, +}; + +static int remote_test_init_tracefs(struct dentry *d, void *unused) +{ + return tracefs_create_file("write_event", 0200, d, NULL, &write_event_fop= s) ? + 0 : -ENOMEM; +} + +static struct trace_remote_callbacks trace_remote_callbacks =3D { + .init =3D remote_test_init_tracefs, + .load_trace_buffer =3D remote_test_load, + .unload_trace_buffer =3D remote_test_unload, + .enable_tracing =3D remote_test_enable_tracing, + .swap_reader_page =3D remote_test_swap_reader_page, + .reset =3D remote_test_reset, + .enable_event =3D remote_test_enable_event, +}; + +static int __init remote_test_init(void) +{ + return trace_remote_register("test", &trace_remote_callbacks, NULL, + &remote_event_selftest, 1); +} + +module_init(remote_test_init); + +MODULE_DESCRIPTION("Test module for the trace remote interface"); +MODULE_AUTHOR("Vincent Donnefort"); +MODULE_LICENSE("GPL"); diff --git a/kernel/trace/remote_test_events.h b/kernel/trace/remote_test_e= vents.h new file mode 100644 index 000000000000..26b93b3406fc --- /dev/null +++ b/kernel/trace/remote_test_events.h @@ -0,0 +1,10 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#define REMOTE_TEST_EVENT_ID 1 + +REMOTE_EVENT(selftest, REMOTE_TEST_EVENT_ID, + RE_STRUCT( + re_field(u64, id) + ), + RE_PRINTK("id=3D%llu", __entry->id) +); 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charset="utf-8" Exercise the tracefs interface for trace remote with a set of tests to check: * loading/unloading (unloading.tc) * reset (reset.tc) * size changes (buffer_size.tc) * consuming read (trace_pipe.tc) * non-consuming read (trace.tc) Cc: Shuah Khan Cc: linux-kselftest@vger.kernel.org Signed-off-by: Vincent Donnefort diff --git a/tools/testing/selftests/ftrace/test.d/remotes/buffer_size.tc b= /tools/testing/selftests/ftrace/test.d/remotes/buffer_size.tc new file mode 100644 index 000000000000..1a43280ffa97 --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/remotes/buffer_size.tc @@ -0,0 +1,25 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# description: Test trace remote buffer size +# requires: remotes/test + +. $TEST_DIR/remotes/functions + +test_buffer_size() +{ + echo 0 > tracing_on + assert_unloaded + + echo 4096 > buffer_size_kb + echo 1 > tracing_on + assert_loaded + + echo 0 > tracing_on + echo 7 > buffer_size_kb +} + +if [ -z "$SOURCE_REMOTE_TEST" ]; then + set -e + setup_remote_test + test_buffer_size +fi diff --git a/tools/testing/selftests/ftrace/test.d/remotes/functions b/tool= s/testing/selftests/ftrace/test.d/remotes/functions new file mode 100644 index 000000000000..97a09d564a34 --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/remotes/functions @@ -0,0 +1,88 @@ +# SPDX-License-Identifier: GPL-2.0 + +setup_remote() +{ + local name=3D$1 + + [ -e $TRACING_DIR/remotes/$name/write_event ] || exit_unresolved + + cd remotes/$name/ + echo 0 > tracing_on + clear_trace + echo 7 > buffer_size_kb + echo 0 > events/enable + echo 1 > events/$name/selftest/enable + echo 1 > tracing_on +} + +setup_remote_test() +{ + [ -d $TRACING_DIR/remotes/test/ ] || modprobe remote_test || exit_unresol= ved + + setup_remote "test" +} + +assert_loaded() +{ + grep -q "(loaded)" buffer_size_kb +} + +assert_unloaded() +{ + grep -q "(unloaded)" buffer_size_kb +} + +dump_trace_pipe() +{ + output=3D$(mktemp $TMPDIR/remote_test.XXXXXX) + cat trace_pipe > $output & + pid=3D$! + sleep 1 + kill -1 $pid + + echo $output +} + +check_trace() +{ + start_id=3D"$1" + end_id=3D"$2" + file=3D"$3" + + # Ensure the file is not empty + test -n "$(head $file)" + + prev_ts=3D0 + id=3D0 + + # Only keep + tmp=3D$(mktemp $TMPDIR/remote_test.XXXXXX) + sed -e 's/\[[0-9]*\]\s*\([0-9]*.[0-9]*\): [a-z]* id=3D\([0-9]*\)/\1 \2/' = $file > $tmp + + while IFS=3D read -r line; do + ts=3D$(echo $line | cut -d ' ' -f 1) + id=3D$(echo $line | cut -d ' ' -f 2) + + test $(echo "$ts>$prev_ts" | bc) -eq 1 + test $id -eq $start_id + + prev_ts=3D$ts + start_id=3D$((start_id + 1)) + done < $tmp + + test $id -eq $end_id + rm $tmp +} + +get_cpu_ids() +{ + sed -n 's/^processor\s*:\s*\([0-9]\+\).*/\1/p' /proc/cpuinfo +} + +get_page_size() { + sed -ne 's/^.*data.*size:\([0-9][0-9]*\).*/\1/p' events/header_page +} + +get_selftest_event_size() { + sed -ne 's/^.*field:.*;.*size:\([0-9][0-9]*\);.*/\1/p' events/*/selfte= st/format | awk '{s+=3D$1} END {print s}' +} diff --git a/tools/testing/selftests/ftrace/test.d/remotes/reset.tc b/tools= /testing/selftests/ftrace/test.d/remotes/reset.tc new file mode 100644 index 000000000000..4d176349b2bc --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/remotes/reset.tc @@ -0,0 +1,90 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# description: Test trace remote reset +# requires: remotes/test + +. $TEST_DIR/remotes/functions + +check_reset() +{ + write_event_path=3D"write_event" + taskset=3D"" + + clear_trace + + # Is the buffer empty? + output=3D$(dump_trace_pipe) + test $(wc -l $output | cut -d ' ' -f1) -eq 0 + + if $(echo $(pwd) | grep -q "per_cpu/cpu"); then + write_event_path=3D"../../write_event" + cpu_id=3D$(echo $(pwd) | sed -e 's/.*per_cpu\/cpu//') + taskset=3D"taskset -c $cpu_id" + fi + rm $output + + # Can we properly write a new event? + $taskset echo 7890 > $write_event_path + output=3D$(dump_trace_pipe) + test $(wc -l $output | cut -d ' ' -f1) -eq 1 + grep -q "id=3D7890" $output + rm $output +} + +test_global_interface() +{ + output=3D$(mktemp $TMPDIR/remote_test.XXXXXX) + + # Confidence check + echo 123456 > write_event + output=3D$(dump_trace_pipe) + grep -q "id=3D123456" $output + rm $output + + # Reset single event + echo 1 > write_event + check_reset + + # Reset lost events + for i in $(seq 1 10000); do + echo 1 > write_event + done + check_reset +} + +test_percpu_interface() +{ + [ "$(get_cpu_ids | wc -l)" -ge 2 ] || return 0 + + for cpu in $(get_cpu_ids); do + taskset -c $cpu echo 1 > write_event + done + + check_non_empty=3D0 + for cpu in $(get_cpu_ids); do + cd per_cpu/cpu$cpu/ + + if [ $check_non_empty -eq 0 ]; then + check_reset + check_non_empty=3D1 + else + # Check we have only reset 1 CPU + output=3D$(dump_trace_pipe) + test $(wc -l $output | cut -d ' ' -f1) -eq 1 + rm $output + fi + cd - + done +} + +test_reset() +{ + test_global_interface + test_percpu_interface +} + +if [ -z "$SOURCE_REMOTE_TEST" ]; then + set -e + setup_remote_test + test_reset +fi diff --git a/tools/testing/selftests/ftrace/test.d/remotes/trace.tc b/tools= /testing/selftests/ftrace/test.d/remotes/trace.tc new file mode 100644 index 000000000000..081133ec45ff --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/remotes/trace.tc @@ -0,0 +1,127 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# description: Test trace remote non-consuming read +# requires: remotes/test + +. $TEST_DIR/remotes/functions + +test_trace() +{ + echo 0 > tracing_on + assert_unloaded + + echo 7 > buffer_size_kb + echo 1 > tracing_on + assert_loaded + + # Simple test: Emit few events and try to read them + for i in $(seq 1 8); do + echo $i > write_event + done + + check_trace 1 8 trace + + # + # Test interaction with consuming read + # + + cat trace_pipe > /dev/null & + pid=3D$! + + sleep 1 + kill $pid + + test $(wc -l < trace) -eq 0 + + for i in $(seq 16 32); do + echo $i > write_event + done + + check_trace 16 32 trace + + # + # Test interaction with reset + # + + echo 0 > trace + + test $(wc -l < trace) -eq 0 + + for i in $(seq 1 8); do + echo $i > write_event + done + + check_trace 1 8 trace + + # + # Test interaction with lost events + # + + # Ensure the writer is not on the reader page by reloading the buffer + echo 0 > tracing_on + echo 0 > trace + assert_unloaded + echo 1 > tracing_on + assert_loaded + + # Ensure ring-buffer overflow by emitting events from the same CPU + for cpu in $(get_cpu_ids); do + break + done + + events_per_page=3D$(($(get_page_size) / $(get_selftest_event_size))) #= Approx: does not take TS into account + nr_events=3D$(($events_per_page * 2)) + for i in $(seq 1 $nr_events); do + taskset -c $cpu echo $i > write_event + done + + id=3D$(sed -n -e '1s/\[[0-9]*\]\s*[0-9]*.[0-9]*: [a-z]* id=3D\([0-9]*\= )/\1/p' trace) + test $id -ne 1 + + check_trace $id $nr_events trace + + # + # Test per-CPU interface + # + echo 0 > trace + + for cpu in $(get_cpu_ids) ; do + taskset -c $cpu echo $cpu > write_event + done + + for cpu in $(get_cpu_ids); do + cd per_cpu/cpu$cpu/ + + check_trace $cpu $cpu trace + + cd - > /dev/null + done + + # + # Test with hotplug + # + + [ "$(get_cpu_ids | wc -l)" -ge 2 ] || return 0 + + echo 0 > trace + + for cpu in $(get_cpu_ids); do + echo 0 > /sys/devices/system/cpu/cpu$cpu/online + break + done + + for i in $(seq 1 8); do + echo $i > write_event + done + + check_trace 1 8 trace + + echo 1 > /sys/devices/system/cpu/cpu$cpu/online +} + +if [ -z "$SOURCE_REMOTE_TEST" ]; then + set -e + + setup_remote_test + test_trace +fi diff --git a/tools/testing/selftests/ftrace/test.d/remotes/trace_pipe.tc b/= tools/testing/selftests/ftrace/test.d/remotes/trace_pipe.tc new file mode 100644 index 000000000000..d28eaee10c7c --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/remotes/trace_pipe.tc @@ -0,0 +1,127 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# description: Test trace remote consuming read +# requires: remotes/test + +. $TEST_DIR/remotes/functions + +test_trace_pipe() +{ + echo 0 > tracing_on + assert_unloaded + + # Emit events from the same CPU + for cpu in $(get_cpu_ids); do + break + done + + # + # Simple test: Emit enough events to fill few pages + # + + echo 1024 > buffer_size_kb + echo 1 > tracing_on + assert_loaded + + events_per_page=3D$(($(get_page_size) / $(get_selftest_event_size))) + nr_events=3D$(($events_per_page * 4)) + + output=3D$(mktemp $TMPDIR/remote_test.XXXXXX) + + cat trace_pipe > $output & + pid=3D$! + + for i in $(seq 1 $nr_events); do + taskset -c $cpu echo $i > write_event + done + + echo 0 > tracing_on + sleep 1 + kill $pid + + check_trace 1 $nr_events $output + + rm $output + + # + # Test interaction with lost events + # + + assert_unloaded + echo 7 > buffer_size_kb + echo 1 > tracing_on + assert_loaded + + nr_events=3D$((events_per_page * 2)) + for i in $(seq 1 $nr_events); do + taskset -c $cpu echo $i > write_event + done + + output=3D$(dump_trace_pipe) + + lost_events=3D$(sed -n -e '1s/CPU:.*\[LOST \([0-9]*\) EVENTS\]/\1/p' $= output) + test -n "$lost_events" + + id=3D$(sed -n -e '2s/\[[0-9]*\]\s*[0-9]*.[0-9]*: [a-z]* id=3D\([0-9]*\= )/\1/p' $output) + test "$id" -eq $(($lost_events + 1)) + + # Drop [LOST EVENTS] line + sed -i '1d' $output + + check_trace $id $nr_events $output + + rm $output + + # + # Test per-CPU interface + # + + echo 0 > trace + echo 1 > tracing_on + + for cpu in $(get_cpu_ids); do + taskset -c $cpu echo $cpu > write_event + done + + for cpu in $(get_cpu_ids); do + cd per_cpu/cpu$cpu/ + output=3D$(dump_trace_pipe) + + check_trace $cpu $cpu $output + + rm $output + cd - > /dev/null + done + + # + # Test interaction with hotplug + # + + [ "$(get_cpu_ids | wc -l)" -ge 2 ] || return 0 + + echo 0 > trace + + for cpu in $(get_cpu_ids); do + echo 0 > /sys/devices/system/cpu/cpu$cpu/online + break + done + + for i in $(seq 1 8); do + echo $i > write_event + done + + output=3D$(dump_trace_pipe) + + check_trace 1 8 $output + + rm $output + + echo 1 > /sys/devices/system/cpu/cpu$cpu/online +} + +if [ -z "$SOURCE_REMOTE_TEST" ]; then + set -e + + setup_remote_test + test_trace_pipe +fi diff --git a/tools/testing/selftests/ftrace/test.d/remotes/unloading.tc b/t= ools/testing/selftests/ftrace/test.d/remotes/unloading.tc new file mode 100644 index 000000000000..cac2190183f6 --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/remotes/unloading.tc @@ -0,0 +1,41 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# description: Test trace remote unloading +# requires: remotes/test + +. $TEST_DIR/remotes/functions + +test_unloading() +{ + # No reader, writing + assert_loaded + + # No reader, no writing + echo 0 > tracing_on + assert_unloaded + + # 1 reader, no writing + cat trace_pipe & + pid=3D$! + sleep 1 + assert_loaded + kill $pid + assert_unloaded + + # No reader, no writing, events + echo 1 > tracing_on + echo 1 > write_event + echo 0 > tracing_on + assert_loaded + + # Test reset + clear_trace + assert_unloaded +} + +if [ -z "$SOURCE_REMOTE_TEST" ]; 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charset="utf-8" Add documentation about the newly introduced tracing remotes framework. Signed-off-by: Vincent Donnefort diff --git a/Documentation/trace/index.rst b/Documentation/trace/index.rst index b4a429dc4f7a..d77ffb7e2d08 100644 --- a/Documentation/trace/index.rst +++ b/Documentation/trace/index.rst @@ -90,6 +90,17 @@ interactions. user_events uprobetracer =20 +Remote Tracing +-------------- + +This section covers the framework to read compatible ring-buffers, written= by +entities outside of the kernel (most likely firmware or hypervisor) + +.. toctree:: + :maxdepth: 1 + + remotes + Additional Resources -------------------- =20 diff --git a/Documentation/trace/remotes.rst b/Documentation/trace/remotes.= rst new file mode 100644 index 000000000000..e7fb3ee96c30 --- /dev/null +++ b/Documentation/trace/remotes.rst @@ -0,0 +1,59 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D +Tracing Remotes +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D + +:Author: Vincent Donnefort + +Overview +=3D=3D=3D=3D=3D=3D=3D=3D +A trace remote relies on ring-buffer remotes to read and control compatible +tracing buffers, written by entity such as firmware or hypervisor. + +Once registered, a tracefs instance will appear for this remote in the Tra= cefs +directory **remotes/**. This remote can be read and controlled using the s= ame +files as regular Tracefs instances such as **trace_pipe**, **tracing_on** = or +**trace**. + +Register a remote +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D +A remote must provide a set of callbacks `struct trace_remote_callbacks` w= hom +description can be found below. Those callbacks allows Tracefs to enable a= nd +disable tracing and events, to load and unload a tracing buffer (a set of +ring-buffers) and to swap a reader page with the head page, which enables +consuming reading. + +.. kernel-doc:: include/linux/trace_remote.h + +Declare a remote event +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D +Macros are provided to ease the declaration of remote events, in a similar +fashion to in-kernel events. A declaration must provide an ID, a descripti= on of +the event arguments and how to print the event: + +.. code-block:: c + + REMOTE_EVENT(foo, EVENT_FOO_ID, + RE_STRUCT( + re_field(u64, bar) + ), + RE_PRINTK("bar=3D%lld", __entry->bar) + ); + +Then those events must be declared in a C file with the following: + +.. code-block:: c + + #define REMOTE_EVENT_INCLUDE_FILE foo_events.h + #include + +This will provide a `struct remote_event remote_event_foo` that can be giv= en to +`trace_remote_register`. + +Simple ring-buffer +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D +A simple implementation for a ring-buffer writer can be found in +kernel/trace/simple_ring_buffer.c. + +.. kernel-doc:: include/linux/simple_ring_buffer.h --=20 2.52.0.107.ga0afd4fd5b-goog From nobody Wed Dec 17 06:12:58 2025 Received: from mail-wm1-f74.google.com (mail-wm1-f74.google.com [209.85.128.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D9CFF313525 for ; 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Tue, 02 Dec 2025 01:36:48 -0800 (PST) Date: Tue, 2 Dec 2025 09:36:10 +0000 In-Reply-To: <20251202093623.2337860-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251202093623.2337860-1-vdonnefort@google.com> X-Mailer: git-send-email 2.52.0.107.ga0afd4fd5b-goog Message-ID: <20251202093623.2337860-18-vdonnefort@google.com> Subject: [PATCH v9 17/30] tracing: load/unload page callbacks for simple_ring_buffer From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-trace-kernel@vger.kernel.org, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, jstultz@google.com, qperret@google.com, will@kernel.org, aneesh.kumar@kernel.org, kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Add load/unload callback used for each admitted page in the ring-buffer. This will be later useful for the pKVM hypervisor which uses a different VA space and need to dynamically map/unmap the ring-buffer pages. Signed-off-by: Vincent Donnefort diff --git a/include/linux/simple_ring_buffer.h b/include/linux/simple_ring= _buffer.h index f324df2f875b..ecd0e988c699 100644 --- a/include/linux/simple_ring_buffer.h +++ b/include/linux/simple_ring_buffer.h @@ -110,4 +110,11 @@ int simple_ring_buffer_reset(struct simple_rb_per_cpu = *cpu_buffer); */ int simple_ring_buffer_swap_reader_page(struct simple_rb_per_cpu *cpu_buff= er); =20 +int __simple_ring_buffer_init(struct simple_rb_per_cpu *cpu_buffer, + struct simple_buffer_page *bpages, + const struct ring_buffer_desc *desc, + void *(*load_page)(unsigned long va), + void (*unload_page)(void *va)); +void __simple_ring_buffer_unload(struct simple_rb_per_cpu *cpu_buffer, + void (*unload_page)(void *)); #endif diff --git a/kernel/trace/simple_ring_buffer.c b/kernel/trace/simple_ring_b= uffer.c index 1d1f40c8c6d8..f01386975266 100644 --- a/kernel/trace/simple_ring_buffer.c +++ b/kernel/trace/simple_ring_buffer.c @@ -71,7 +71,7 @@ static void simple_bpage_reset(struct simple_buffer_page = *bpage) local_set(&bpage->page->commit, 0); } =20 -static void simple_bpage_init(struct simple_buffer_page *bpage, unsigned l= ong page) +static void simple_bpage_init(struct simple_buffer_page *bpage, void *page) { INIT_LIST_HEAD(&bpage->link); bpage->page =3D (struct buffer_data_page *)page; @@ -342,10 +342,15 @@ int simple_ring_buffer_reset(struct simple_rb_per_cpu= *cpu_buffer) } EXPORT_SYMBOL_GPL(simple_ring_buffer_reset); =20 -int simple_ring_buffer_init(struct simple_rb_per_cpu *cpu_buffer, struct s= imple_buffer_page *bpages, - const struct ring_buffer_desc *desc) +int __simple_ring_buffer_init(struct simple_rb_per_cpu *cpu_buffer, + struct simple_buffer_page *bpages, + const struct ring_buffer_desc *desc, + void *(*load_page)(unsigned long va), + void (*unload_page)(void *va)) { struct simple_buffer_page *bpage =3D bpages; + int ret =3D 0; + void *page; int i; =20 /* At least 1 reader page and two pages in the ring-buffer */ @@ -354,15 +359,22 @@ int simple_ring_buffer_init(struct simple_rb_per_cpu = *cpu_buffer, struct simple_ =20 memset(cpu_buffer, 0, sizeof(*cpu_buffer)); =20 - cpu_buffer->bpages =3D bpages; + cpu_buffer->meta =3D load_page(desc->meta_va); + if (!cpu_buffer->meta) + return -EINVAL; =20 - cpu_buffer->meta =3D (void *)desc->meta_va; memset(cpu_buffer->meta, 0, sizeof(*cpu_buffer->meta)); cpu_buffer->meta->meta_page_size =3D PAGE_SIZE; cpu_buffer->meta->nr_subbufs =3D cpu_buffer->nr_pages; =20 /* The reader page is not part of the ring initially */ - simple_bpage_init(bpage, desc->page_va[0]); + page =3D load_page(desc->page_va[0]); + if (!page) { + unload_page(cpu_buffer->meta); + return -EINVAL; + } + + simple_bpage_init(bpage, page); bpage->id =3D 0; =20 cpu_buffer->nr_pages =3D 1; @@ -372,7 +384,13 @@ int simple_ring_buffer_init(struct simple_rb_per_cpu *= cpu_buffer, struct simple_ cpu_buffer->head_page =3D bpage + 1; =20 for (i =3D 1; i < desc->nr_page_va; i++) { - simple_bpage_init(++bpage, desc->page_va[i]); + page =3D load_page(desc->page_va[i]); + if (!page) { + ret =3D -EINVAL; + break; + } + + simple_bpage_init(++bpage, page); =20 bpage->link.next =3D &(bpage + 1)->link; bpage->link.prev =3D &(bpage - 1)->link; @@ -381,6 +399,14 @@ int simple_ring_buffer_init(struct simple_rb_per_cpu *= cpu_buffer, struct simple_ cpu_buffer->nr_pages =3D i + 1; } =20 + if (ret) { + for (i--; i >=3D 0; i--) + unload_page((void *)desc->page_va[i]); + unload_page(cpu_buffer->meta); + + return ret; + } + /* Close the ring */ bpage->link.next =3D &cpu_buffer->tail_page->link; cpu_buffer->tail_page->link.prev =3D &bpage->link; @@ -388,21 +414,48 @@ int simple_ring_buffer_init(struct simple_rb_per_cpu = *cpu_buffer, struct simple_ /* The last init'ed page points to the head page */ simple_bpage_set_head_link(bpage); =20 + cpu_buffer->bpages =3D bpages; + return 0; } EXPORT_SYMBOL_GPL(simple_ring_buffer_init); =20 -void simple_ring_buffer_unload(struct simple_rb_per_cpu *cpu_buffer) +static void *__load_page(unsigned long page) { + return (void *)page; +} + +static void __unload_page(void *page) { } + +int simple_ring_buffer_init(struct simple_rb_per_cpu *cpu_buffer, struct s= imple_buffer_page *bpages, + const struct ring_buffer_desc *desc) +{ + return __simple_ring_buffer_init(cpu_buffer, bpages, desc, __load_page, _= _unload_page); 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charset="utf-8" The simple_ring_buffer implementation must remain simple enough to be used by the pKVM hypervisor. Prevent the object build if unresolved symbols are found. Signed-off-by: Vincent Donnefort diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile index 53534447e70b..38523ea2e19b 100644 --- a/kernel/trace/Makefile +++ b/kernel/trace/Makefile @@ -114,4 +114,20 @@ obj-$(CONFIG_TRACE_REMOTE) +=3D trace_remote.o obj-$(CONFIG_SIMPLE_RING_BUFFER) +=3D simple_ring_buffer.o obj-$(CONFIG_TRACE_REMOTE_TEST) +=3D remote_test.o =20 +# +# simple_ring_buffer is used by the pKVM hypervisor which does not have ac= cess +# to all kernel symbols. 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Tue, 02 Dec 2025 01:36:50 -0800 (PST) Date: Tue, 2 Dec 2025 09:36:12 +0000 In-Reply-To: <20251202093623.2337860-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251202093623.2337860-1-vdonnefort@google.com> X-Mailer: git-send-email 2.52.0.107.ga0afd4fd5b-goog Message-ID: <20251202093623.2337860-20-vdonnefort@google.com> Subject: [PATCH v9 19/30] KVM: arm64: Add PKVM_DISABLE_STAGE2_ON_PANIC From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-trace-kernel@vger.kernel.org, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, jstultz@google.com, qperret@google.com, will@kernel.org, aneesh.kumar@kernel.org, kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort , Kalesh Singh Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" On NVHE_EL2_DEBUG, when using pKVM, the host stage-2 is relaxed to grant the kernel access to the stacktrace, hypervisor bug table and text to symbolize addresses. This is unsafe for production. In preparation for adding more debug options to NVHE_EL2_DEBUG, decouple the stage-2 relaxation into a separate option. While at it, rename PROTECTED_NVHE_STACKTRACE into PKVM_STACKTRACE, following the same naming scheme as PKVM_DISABLE_STAGE2_ON_PANIC. Cc: Kalesh Singh Signed-off-by: Vincent Donnefort diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig index 4f803fd1c99a..6498dec00fe9 100644 --- a/arch/arm64/kvm/Kconfig +++ b/arch/arm64/kvm/Kconfig @@ -43,9 +43,27 @@ menuconfig KVM =20 If unsure, say N. =20 +if KVM + +config PTDUMP_STAGE2_DEBUGFS + bool "Present the stage-2 pagetables to debugfs" + depends on DEBUG_KERNEL + depends on DEBUG_FS + depends on ARCH_HAS_PTDUMP + select PTDUMP + default n + help + Say Y here if you want to show the stage-2 kernel pagetables + layout in a debugfs file. This information is only useful for kernel de= velopers + who are working in architecture specific areas of the kernel. + It is probably not a good idea to enable this feature in a production + kernel. + + If in doubt, say N. + config NVHE_EL2_DEBUG bool "Debug mode for non-VHE EL2 object" - depends on KVM + default n help Say Y here to enable the debug mode for the non-VHE KVM EL2 object. Failure reports will BUG() in the hypervisor. This is intended for @@ -53,10 +71,23 @@ config NVHE_EL2_DEBUG =20 If unsure, say N. =20 -config PROTECTED_NVHE_STACKTRACE - bool "Protected KVM hypervisor stacktraces" - depends on NVHE_EL2_DEBUG +if NVHE_EL2_DEBUG + +config PKVM_DISABLE_STAGE2_ON_PANIC + bool "Disable the host stage-2 on panic" default n + help + Relax the host stage-2 on hypervisor panic to allow the kernel to + unwind and symbolize the hypervisor stacktrace. This however tampers + the system security. This is intended for local EL2 hypervisor + development. + + If unsure, say N. + +config PKVM_STACKTRACE + bool "Protected KVM hypervisor stacktraces" + depends on PKVM_DISABLE_STAGE2_ON_PANIC + default y help Say Y here to enable pKVM hypervisor stacktraces on hyp_panic() =20 @@ -66,21 +97,6 @@ config PROTECTED_NVHE_STACKTRACE =20 If unsure, or not using protected nVHE (pKVM), say N. =20 -config PTDUMP_STAGE2_DEBUGFS - bool "Present the stage-2 pagetables to debugfs" - depends on KVM - depends on DEBUG_KERNEL - depends on DEBUG_FS - depends on ARCH_HAS_PTDUMP - select PTDUMP - default n - help - Say Y here if you want to show the stage-2 kernel pagetables - layout in a debugfs file. This information is only useful for kernel de= velopers - who are working in architecture specific areas of the kernel. - It is probably not a good idea to enable this feature in a production - kernel. - - If in doubt, say N. - +endif # NVHE_EL2_DEBUG +endif # KVM endif # VIRTUALIZATION diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c index cc7d5d1709cb..54aedf93c78b 100644 --- a/arch/arm64/kvm/handle_exit.c +++ b/arch/arm64/kvm/handle_exit.c @@ -539,7 +539,7 @@ void __noreturn __cold nvhe_hyp_panic_handler(u64 esr, = u64 spsr, =20 /* All hyp bugs, including warnings, are treated as fatal. */ if (!is_protected_kvm_enabled() || - IS_ENABLED(CONFIG_NVHE_EL2_DEBUG)) { + IS_ENABLED(CONFIG_PKVM_DISABLE_STAGE2_ON_PANIC)) { struct bug_entry *bug =3D find_bug(elr_in_kimg); =20 if (bug) diff --git a/arch/arm64/kvm/hyp/nvhe/host.S b/arch/arm64/kvm/hyp/nvhe/host.S index eef15b374abb..3092befcd97c 100644 --- a/arch/arm64/kvm/hyp/nvhe/host.S +++ b/arch/arm64/kvm/hyp/nvhe/host.S @@ -120,7 +120,7 @@ SYM_FUNC_START(__hyp_do_panic) =20 mov x29, x0 =20 -#ifdef CONFIG_NVHE_EL2_DEBUG +#ifdef PKVM_DISABLE_STAGE2_ON_PANIC /* Ensure host stage-2 is disabled */ mrs x0, hcr_el2 bic x0, x0, #HCR_VM diff --git a/arch/arm64/kvm/hyp/nvhe/stacktrace.c b/arch/arm64/kvm/hyp/nvhe= /stacktrace.c index 5b6eeab1a774..7c832d60d22b 100644 --- a/arch/arm64/kvm/hyp/nvhe/stacktrace.c +++ b/arch/arm64/kvm/hyp/nvhe/stacktrace.c @@ -34,7 +34,7 @@ static void hyp_prepare_backtrace(unsigned long fp, unsig= ned long pc) stacktrace_info->pc =3D pc; } =20 -#ifdef CONFIG_PROTECTED_NVHE_STACKTRACE +#ifdef CONFIG_PKVM_STACKTRACE #include =20 DEFINE_PER_CPU(unsigned long [NVHE_STACKTRACE_SIZE/sizeof(long)], pkvm_sta= cktrace); @@ -134,11 +134,11 @@ static void pkvm_save_backtrace(unsigned long fp, uns= igned long pc) =20 unwind(&state, pkvm_save_backtrace_entry, &idx); } -#else /* !CONFIG_PROTECTED_NVHE_STACKTRACE */ +#else /* !CONFIG_PKVM_STACKTRACE */ static void pkvm_save_backtrace(unsigned long fp, unsigned long pc) { } -#endif /* CONFIG_PROTECTED_NVHE_STACKTRACE */ +#endif /* CONFIG_PKVM_STACKTRACE */ =20 /* * kvm_nvhe_prepare_backtrace - prepare to dump the nVHE backtrace diff --git a/arch/arm64/kvm/stacktrace.c b/arch/arm64/kvm/stacktrace.c index af5eec681127..9724c320126b 100644 --- a/arch/arm64/kvm/stacktrace.c +++ b/arch/arm64/kvm/stacktrace.c @@ -197,7 +197,7 @@ static void hyp_dump_backtrace(unsigned long hyp_offset) kvm_nvhe_dump_backtrace_end(); } =20 -#ifdef CONFIG_PROTECTED_NVHE_STACKTRACE +#ifdef CONFIG_PKVM_STACKTRACE DECLARE_KVM_NVHE_PER_CPU(unsigned long [NVHE_STACKTRACE_SIZE/sizeof(long)], pkvm_stacktrace); 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Tue, 02 Dec 2025 01:36:50 -0800 (PST) Date: Tue, 2 Dec 2025 09:36:13 +0000 In-Reply-To: <20251202093623.2337860-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251202093623.2337860-1-vdonnefort@google.com> X-Mailer: git-send-email 2.52.0.107.ga0afd4fd5b-goog Message-ID: <20251202093623.2337860-21-vdonnefort@google.com> Subject: [PATCH v9 20/30] KVM: arm64: Add clock support to nVHE/pKVM hyp From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-trace-kernel@vger.kernel.org, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, jstultz@google.com, qperret@google.com, will@kernel.org, aneesh.kumar@kernel.org, kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" In preparation for supporting tracing from the nVHE hyp, add support to generate timestamps with a clock fed by the CNTCVT counter. The clock can be kept in sync with the kernel's by updating the slope values. This will be done later. As current we do only create a trace clock, make the whole support dependant on the upcoming CONFIG_NVHE_EL2_TRACING. Signed-off-by: Vincent Donnefort diff --git a/arch/arm64/kvm/hyp/include/nvhe/clock.h b/arch/arm64/kvm/hyp/i= nclude/nvhe/clock.h new file mode 100644 index 000000000000..9f429f5c0664 --- /dev/null +++ b/arch/arm64/kvm/hyp/include/nvhe/clock.h @@ -0,0 +1,16 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ARM64_KVM_HYP_NVHE_CLOCK_H +#define __ARM64_KVM_HYP_NVHE_CLOCK_H +#include + +#include + +#ifdef CONFIG_NVHE_EL2_TRACING +void trace_clock_update(u32 mult, u32 shift, u64 epoch_ns, u64 epoch_cyc); +u64 trace_clock(void); +#else +static inline void +trace_clock_update(u32 mult, u32 shift, u64 epoch_ns, u64 epoch_cyc) { } +static inline u64 trace_clock(void) { return 0; } +#endif +#endif diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Mak= efile index a244ec25f8c5..8dc95257c291 100644 --- a/arch/arm64/kvm/hyp/nvhe/Makefile +++ b/arch/arm64/kvm/hyp/nvhe/Makefile @@ -17,7 +17,7 @@ ccflags-y +=3D -fno-stack-protector \ hostprogs :=3D gen-hyprel HOST_EXTRACFLAGS +=3D -I$(objtree)/include =20 -lib-objs :=3D clear_page.o copy_page.o memcpy.o memset.o +lib-objs :=3D clear_page.o copy_page.o memcpy.o memset.o tishift.o lib-objs :=3D $(addprefix ../../../lib/, $(lib-objs)) =20 CFLAGS_switch.nvhe.o +=3D -Wno-override-init @@ -29,6 +29,7 @@ hyp-obj-y +=3D ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cp= uif-proxy.o ../entry.o \ ../fpsimd.o ../hyp-entry.o ../exception.o ../pgtable.o hyp-obj-y +=3D ../../../kernel/smccc-call.o hyp-obj-$(CONFIG_LIST_HARDENED) +=3D list_debug.o +hyp-obj-$(CONFIG_NVHE_EL2_TRACING) +=3D clock.o hyp-obj-y +=3D $(lib-objs) =20 ## diff --git a/arch/arm64/kvm/hyp/nvhe/clock.c b/arch/arm64/kvm/hyp/nvhe/cloc= k.c new file mode 100644 index 000000000000..32fc4313fe43 --- /dev/null +++ b/arch/arm64/kvm/hyp/nvhe/clock.c @@ -0,0 +1,65 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2025 Google LLC + * Author: Vincent Donnefort + */ + +#include + +#include +#include + +static struct clock_data { + struct { + u32 mult; + u32 shift; + u64 epoch_ns; + u64 epoch_cyc; + u64 cyc_overflow64; + } data[2]; + u64 cur; +} trace_clock_data; + +static u64 __clock_mult_uint128(u64 cyc, u32 mult, u32 shift) +{ + __uint128_t ns =3D (__uint128_t)cyc * mult; + + ns >>=3D shift; + + return (u64)ns; +} + +/* Does not guarantee no reader on the modified bank. */ +void trace_clock_update(u32 mult, u32 shift, u64 epoch_ns, u64 epoch_cyc) +{ + struct clock_data *clock =3D &trace_clock_data; + u64 bank =3D clock->cur ^ 1; + + clock->data[bank].mult =3D mult; + clock->data[bank].shift =3D shift; + clock->data[bank].epoch_ns =3D epoch_ns; + clock->data[bank].epoch_cyc =3D epoch_cyc; + clock->data[bank].cyc_overflow64 =3D ULONG_MAX / mult; + + smp_store_release(&clock->cur, bank); +} + +/* Use untrusted host data */ +u64 trace_clock(void) +{ + struct clock_data *clock =3D &trace_clock_data; + u64 bank =3D smp_load_acquire(&clock->cur); + u64 cyc, ns; + + cyc =3D __arch_counter_get_cntvct() - clock->data[bank].epoch_cyc; + + if (likely(cyc < clock->data[bank].cyc_overflow64)) { + ns =3D cyc * clock->data[bank].mult; 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charset="utf-8" Knowing the number of CPUs is necessary for determining the boundaries of per-cpu variables, which will be used for upcoming hypervisor tracing. hyp_nr_cpus which stores this value, is only initialised for the pKVM hypervisor. Make it accessible for the nVHE hypervisor as well. With the kernel now responsible for initialising hyp_nr_cpus, the nr_cpus parameter is no longer needed in __pkvm_init. Signed-off-by: Vincent Donnefort diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_= hyp.h index e6be1f5d0967..b169d85458f9 100644 --- a/arch/arm64/include/asm/kvm_hyp.h +++ b/arch/arm64/include/asm/kvm_hyp.h @@ -128,8 +128,7 @@ void __noreturn __hyp_do_panic(struct kvm_cpu_context *= host_ctxt, u64 spsr, #ifdef __KVM_NVHE_HYPERVISOR__ void __pkvm_init_switch_pgd(phys_addr_t pgd, unsigned long sp, void (*fn)(void)); -int __pkvm_init(phys_addr_t phys, unsigned long size, unsigned long nr_cpu= s, - unsigned long *per_cpu_base, u32 hyp_va_bits); +int __pkvm_init(phys_addr_t phys, unsigned long size, unsigned long *per_c= pu_base, u32 hyp_va_bits); void __noreturn __host_enter(struct kvm_cpu_context *host_ctxt); #endif =20 @@ -146,5 +145,6 @@ extern u64 kvm_nvhe_sym(id_aa64smfr0_el1_sys_val); extern unsigned long kvm_nvhe_sym(__icache_flags); extern unsigned int kvm_nvhe_sym(kvm_arm_vmid_bits); extern unsigned int kvm_nvhe_sym(kvm_host_sve_max_vl); +extern unsigned long kvm_nvhe_sym(hyp_nr_cpus); =20 #endif /* __ARM64_KVM_HYP_H__ */ diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 052bf0d4d0b0..7ba427f9608c 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -35,6 +35,7 @@ #include #include #include +#include #include #include #include @@ -2396,7 +2397,7 @@ static int __init do_pkvm_init(u32 hyp_va_bits) preempt_disable(); cpu_hyp_init_context(); ret =3D kvm_call_hyp_nvhe(__pkvm_init, hyp_mem_base, hyp_mem_size, - num_possible_cpus(), kern_hyp_va(per_cpu_base), + kern_hyp_va(per_cpu_base), hyp_va_bits); cpu_hyp_init_features(); =20 @@ -2605,6 +2606,8 @@ static int __init init_hyp_mode(void) kvm_nvhe_sym(kvm_arm_hyp_percpu_base)[cpu] =3D (unsigned long)page_addr; } =20 + kvm_nvhe_sym(hyp_nr_cpus) =3D num_possible_cpus(); + /* * Map the Hyp-code called directly from the host */ diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm= /hyp/include/nvhe/mem_protect.h index 5f9d56754e39..f8a7b8c04c49 100644 --- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h +++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h @@ -30,8 +30,6 @@ enum pkvm_component_id { PKVM_ID_FFA, }; =20 -extern unsigned long hyp_nr_cpus; - int __pkvm_prot_finalize(void); int __pkvm_host_share_hyp(u64 pfn); int __pkvm_host_unshare_hyp(u64 pfn); diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/h= yp-main.c index 29430c031095..34546dce57ff 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -482,17 +482,15 @@ static void handle___pkvm_init(struct kvm_cpu_context= *host_ctxt) { DECLARE_REG(phys_addr_t, phys, host_ctxt, 1); DECLARE_REG(unsigned long, size, host_ctxt, 2); - DECLARE_REG(unsigned long, nr_cpus, host_ctxt, 3); - DECLARE_REG(unsigned long *, per_cpu_base, host_ctxt, 4); - DECLARE_REG(u32, hyp_va_bits, host_ctxt, 5); + DECLARE_REG(unsigned long *, per_cpu_base, host_ctxt, 3); + DECLARE_REG(u32, hyp_va_bits, host_ctxt, 4); =20 /* * __pkvm_init() will return only if an error occurred, otherwise it * will tail-call in __pkvm_init_finalise() which will have to deal * with the host context directly. */ - cpu_reg(host_ctxt, 1) =3D __pkvm_init(phys, size, nr_cpus, per_cpu_base, - hyp_va_bits); 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charset="utf-8" Return the fixmap VA with the page offset, instead of the page base address. This allows to use hyp_fixmap_map() seamlessly regardless of the address alignment. While at it, do the same for hyp_fixblock_map(). Signed-off-by: Vincent Donnefort diff --git a/arch/arm64/kvm/hyp/nvhe/mm.c b/arch/arm64/kvm/hyp/nvhe/mm.c index ae8391baebc3..a6eafd72f87c 100644 --- a/arch/arm64/kvm/hyp/nvhe/mm.c +++ b/arch/arm64/kvm/hyp/nvhe/mm.c @@ -244,7 +244,7 @@ static void *fixmap_map_slot(struct hyp_fixmap_slot *sl= ot, phys_addr_t phys) =20 void *hyp_fixmap_map(phys_addr_t phys) { - return fixmap_map_slot(this_cpu_ptr(&fixmap_slots), phys); + return fixmap_map_slot(this_cpu_ptr(&fixmap_slots), phys) + offset_in_pag= e(phys); } =20 static void fixmap_clear_slot(struct hyp_fixmap_slot *slot) @@ -366,7 +366,7 @@ void *hyp_fixblock_map(phys_addr_t phys, size_t *size) #ifdef HAS_FIXBLOCK *size =3D PMD_SIZE; hyp_spin_lock(&hyp_fixblock_lock); - return fixmap_map_slot(&hyp_fixblock_slot, phys); + return fixmap_map_slot(&hyp_fixblock_slot, phys) + offset_in_page(phys); #else *size =3D PAGE_SIZE; return hyp_fixmap_map(phys); --=20 2.52.0.107.ga0afd4fd5b-goog From nobody Wed Dec 17 06:12:58 2025 Received: from mail-wm1-f74.google.com (mail-wm1-f74.google.com [209.85.128.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4A4CA3168E0 for ; 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Tue, 02 Dec 2025 01:36:53 -0800 (PST) Date: Tue, 2 Dec 2025 09:36:16 +0000 In-Reply-To: <20251202093623.2337860-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251202093623.2337860-1-vdonnefort@google.com> X-Mailer: git-send-email 2.52.0.107.ga0afd4fd5b-goog Message-ID: <20251202093623.2337860-24-vdonnefort@google.com> Subject: [PATCH v9 23/30] KVM: arm64: Add tracing capability for the nVHE/pKVM hyp From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-trace-kernel@vger.kernel.org, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, jstultz@google.com, qperret@google.com, will@kernel.org, aneesh.kumar@kernel.org, kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" There is currently no way to inspect or log what's happening at EL2 when the nVHE or pKVM hypervisor is used. With the growing set of features for pKVM, the need for tooling is more pressing. And tracefs, by its reliability, versatility and support for user-space is fit for purpose. Add support to write into a tracefs compatible ring-buffer. There's no way the hypervisor could log events directly into the host tracefs ring-buffers. So instead let's use our own, where the hypervisor is the writer and the host the reader. Signed-off-by: Vincent Donnefort diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_= asm.h index 9da54d4ee49e..f83650a7aad9 100644 --- a/arch/arm64/include/asm/kvm_asm.h +++ b/arch/arm64/include/asm/kvm_asm.h @@ -89,6 +89,10 @@ enum __kvm_host_smccc_func { __KVM_HOST_SMCCC_FUNC___pkvm_vcpu_load, __KVM_HOST_SMCCC_FUNC___pkvm_vcpu_put, __KVM_HOST_SMCCC_FUNC___pkvm_tlb_flush_vmid, + __KVM_HOST_SMCCC_FUNC___tracing_load, + __KVM_HOST_SMCCC_FUNC___tracing_unload, + __KVM_HOST_SMCCC_FUNC___tracing_enable, + __KVM_HOST_SMCCC_FUNC___tracing_swap_reader, }; =20 #define DECLARE_KVM_VHE_SYM(sym) extern char sym[] diff --git a/arch/arm64/include/asm/kvm_hyptrace.h b/arch/arm64/include/asm= /kvm_hyptrace.h new file mode 100644 index 000000000000..9c30a479bc36 --- /dev/null +++ b/arch/arm64/include/asm/kvm_hyptrace.h @@ -0,0 +1,13 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef __ARM64_KVM_HYPTRACE_H_ +#define __ARM64_KVM_HYPTRACE_H_ + +#include + +struct hyp_trace_desc { + unsigned long bpages_backing_start; + size_t bpages_backing_size; + struct trace_buffer_desc trace_buffer_desc; + +}; +#endif diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig index 6498dec00fe9..c7f50492f2cf 100644 --- a/arch/arm64/kvm/Kconfig +++ b/arch/arm64/kvm/Kconfig @@ -73,6 +73,11 @@ config NVHE_EL2_DEBUG =20 if NVHE_EL2_DEBUG =20 +config NVHE_EL2_TRACING + bool + depends on TRACING + default y + config PKVM_DISABLE_STAGE2_ON_PANIC bool "Disable the host stage-2 on panic" default n diff --git a/arch/arm64/kvm/hyp/include/nvhe/trace.h b/arch/arm64/kvm/hyp/i= nclude/nvhe/trace.h new file mode 100644 index 000000000000..7da8788ce527 --- /dev/null +++ b/arch/arm64/kvm/hyp/include/nvhe/trace.h @@ -0,0 +1,23 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef __ARM64_KVM_HYP_NVHE_TRACE_H +#define __ARM64_KVM_HYP_NVHE_TRACE_H +#include + +#ifdef CONFIG_NVHE_EL2_TRACING +void *tracing_reserve_entry(unsigned long length); +void tracing_commit_entry(void); + +int __tracing_load(unsigned long desc_va, size_t desc_size); +void __tracing_unload(void); +int __tracing_enable(bool enable); +int __tracing_swap_reader(unsigned int cpu); +#else +static inline void *tracing_reserve_entry(unsigned long length) { return N= ULL; } +static inline void tracing_commit_entry(void) { } + +static inline int __tracing_load(unsigned long desc_va, size_t desc_size) = { return -ENODEV; } +static inline void __tracing_unload(void) { } +static inline int __tracing_enable(bool enable) { return -ENODEV; } +static inline int __tracing_swap_reader(unsigned int cpu) { return -ENODEV= ; } +#endif +#endif diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Mak= efile index 8dc95257c291..f1840628d2d6 100644 --- a/arch/arm64/kvm/hyp/nvhe/Makefile +++ b/arch/arm64/kvm/hyp/nvhe/Makefile @@ -29,9 +29,12 @@ hyp-obj-y +=3D ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-c= puif-proxy.o ../entry.o \ ../fpsimd.o ../hyp-entry.o ../exception.o ../pgtable.o hyp-obj-y +=3D ../../../kernel/smccc-call.o hyp-obj-$(CONFIG_LIST_HARDENED) +=3D list_debug.o -hyp-obj-$(CONFIG_NVHE_EL2_TRACING) +=3D clock.o +hyp-obj-$(CONFIG_NVHE_EL2_TRACING) +=3D clock.o trace.o hyp-obj-y +=3D $(lib-objs) =20 +# Path to simple_ring_buffer.c +CFLAGS_trace.nvhe.o +=3D -I$(objtree)/kernel/trace/ + ## ## Build rules for compiling nVHE hyp code ## Output of this folder is `kvm_nvhe.o`, a partially linked object diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/h= yp-main.c index 34546dce57ff..8b78b29c2069 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -18,6 +18,7 @@ #include #include #include +#include #include =20 DEFINE_PER_CPU(struct kvm_nvhe_init_params, kvm_init_params); @@ -583,6 +584,35 @@ static void handle___pkvm_teardown_vm(struct kvm_cpu_c= ontext *host_ctxt) cpu_reg(host_ctxt, 1) =3D __pkvm_teardown_vm(handle); } =20 +static void handle___tracing_load(struct kvm_cpu_context *host_ctxt) +{ + DECLARE_REG(unsigned long, desc_hva, host_ctxt, 1); + DECLARE_REG(size_t, desc_size, host_ctxt, 2); + + cpu_reg(host_ctxt, 1) =3D __tracing_load(desc_hva, desc_size); +} + +static void handle___tracing_unload(struct kvm_cpu_context *host_ctxt) +{ + __tracing_unload(); + + cpu_reg(host_ctxt, 1) =3D 0; +} + +static void handle___tracing_enable(struct kvm_cpu_context *host_ctxt) +{ + DECLARE_REG(bool, enable, host_ctxt, 1); + + cpu_reg(host_ctxt, 1) =3D __tracing_enable(enable); +} + +static void handle___tracing_swap_reader(struct kvm_cpu_context *host_ctxt) +{ + DECLARE_REG(unsigned int, cpu, host_ctxt, 1); + + cpu_reg(host_ctxt, 1) =3D __tracing_swap_reader(cpu); +} + typedef void (*hcall_t)(struct kvm_cpu_context *); =20 #define HANDLE_FUNC(x) [__KVM_HOST_SMCCC_FUNC_##x] =3D (hcall_t)handle_##x @@ -624,6 +654,10 @@ static const hcall_t host_hcall[] =3D { HANDLE_FUNC(__pkvm_vcpu_load), HANDLE_FUNC(__pkvm_vcpu_put), HANDLE_FUNC(__pkvm_tlb_flush_vmid), + HANDLE_FUNC(__tracing_load), + HANDLE_FUNC(__tracing_unload), + HANDLE_FUNC(__tracing_enable), + HANDLE_FUNC(__tracing_swap_reader), }; =20 static void handle_host_hcall(struct kvm_cpu_context *host_ctxt) diff --git a/arch/arm64/kvm/hyp/nvhe/trace.c b/arch/arm64/kvm/hyp/nvhe/trac= e.c new file mode 100644 index 000000000000..df9d66fcb3c9 --- /dev/null +++ b/arch/arm64/kvm/hyp/nvhe/trace.c @@ -0,0 +1,273 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2025 Google LLC + * Author: Vincent Donnefort + */ + +#include +#include +#include +#include + +#include +#include +#include + +#include "simple_ring_buffer.c" + +static DEFINE_PER_CPU(struct simple_rb_per_cpu, __simple_rbs); + +static struct hyp_trace_buffer { + struct simple_rb_per_cpu __percpu *simple_rbs; + void *bpages_backing_start; + size_t bpages_backing_size; + hyp_spinlock_t lock; +} trace_buffer =3D { + .simple_rbs =3D &__simple_rbs, + .lock =3D __HYP_SPIN_LOCK_UNLOCKED, +}; + +static bool hyp_trace_buffer_loaded(struct hyp_trace_buffer *trace_buffer) +{ + return trace_buffer->bpages_backing_size > 0; +} + +void *tracing_reserve_entry(unsigned long length) +{ + return simple_ring_buffer_reserve(this_cpu_ptr(trace_buffer.simple_rbs), = length, + trace_clock()); +} + +void tracing_commit_entry(void) +{ + simple_ring_buffer_commit(this_cpu_ptr(trace_buffer.simple_rbs)); +} + +static int __admit_host_mem(void *start, u64 size) +{ + if (!PAGE_ALIGNED(start) || !PAGE_ALIGNED(size) || !size) + return -EINVAL; + + if (!is_protected_kvm_enabled()) + return 0; + + return __pkvm_host_donate_hyp(hyp_virt_to_pfn(start), size >> PAGE_SHIFT); +} + +static void __release_host_mem(void *start, u64 size) +{ + if (!is_protected_kvm_enabled()) + return; + + WARN_ON(__pkvm_hyp_donate_host(hyp_virt_to_pfn(start), size >> PAGE_SHIFT= )); +} + +static int hyp_trace_buffer_load_bpage_backing(struct hyp_trace_buffer *tr= ace_buffer, + struct hyp_trace_desc *desc) +{ + void *start =3D (void *)kern_hyp_va(desc->bpages_backing_start); + size_t size =3D desc->bpages_backing_size; + int ret; + + ret =3D __admit_host_mem(start, size); + if (ret) + return ret; + + memset(start, 0, size); + + trace_buffer->bpages_backing_start =3D start; + trace_buffer->bpages_backing_size =3D size; + + return 0; +} + +static void hyp_trace_buffer_unload_bpage_backing(struct hyp_trace_buffer = *trace_buffer) +{ + void *start =3D trace_buffer->bpages_backing_start; + size_t size =3D trace_buffer->bpages_backing_size; + + if (!size) + return; + + memset(start, 0, size); + + __release_host_mem(start, size); + + trace_buffer->bpages_backing_start =3D 0; + trace_buffer->bpages_backing_size =3D 0; +} + +static void *__pin_shared_page(unsigned long kern_va) +{ + void *va =3D kern_hyp_va((void *)kern_va); + + if (!is_protected_kvm_enabled()) + return va; + + return hyp_pin_shared_mem(va, va + PAGE_SIZE) ? NULL : va; +} + +static void __unpin_shared_page(void *va) +{ + if (!is_protected_kvm_enabled()) + return; + + hyp_unpin_shared_mem(va, va + PAGE_SIZE); +} + +static void hyp_trace_buffer_unload(struct hyp_trace_buffer *trace_buffer) +{ + int cpu; + + hyp_assert_lock_held(&trace_buffer->lock); + + if (!hyp_trace_buffer_loaded(trace_buffer)) + return; + + for (cpu =3D 0; cpu < hyp_nr_cpus; cpu++) + __simple_ring_buffer_unload(per_cpu_ptr(trace_buffer->simple_rbs, cpu), + __unpin_shared_page); + + hyp_trace_buffer_unload_bpage_backing(trace_buffer); +} + +static int hyp_trace_buffer_load(struct hyp_trace_buffer *trace_buffer, + struct hyp_trace_desc *desc) +{ + struct simple_buffer_page *bpages; + struct ring_buffer_desc *rb_desc; + int ret, cpu; + + hyp_assert_lock_held(&trace_buffer->lock); + + if (hyp_trace_buffer_loaded(trace_buffer)) + return -EINVAL; + + ret =3D hyp_trace_buffer_load_bpage_backing(trace_buffer, desc); + if (ret) + return ret; + + bpages =3D trace_buffer->bpages_backing_start; + for_each_ring_buffer_desc(rb_desc, cpu, &desc->trace_buffer_desc) { + ret =3D __simple_ring_buffer_init(per_cpu_ptr(trace_buffer->simple_rbs, = cpu), + bpages, rb_desc, __pin_shared_page, + __unpin_shared_page); + if (ret) + break; + + bpages +=3D rb_desc->nr_page_va; + } + + if (ret) + hyp_trace_buffer_unload(trace_buffer); + + return ret; +} + +static bool hyp_trace_desc_validate(struct hyp_trace_desc *desc, size_t de= sc_size) +{ + struct ring_buffer_desc *rb_desc; + unsigned int cpu; + size_t nr_bpages; + void *desc_end; + + /* + * Both desc_size and bpages_backing_size are untrusted host-provided + * values. We rely on __pkvm_host_donate_hyp() to enforce their validity. + */ + desc_end =3D (void *)desc + desc_size; + nr_bpages =3D desc->bpages_backing_size / sizeof(struct simple_buffer_pag= e); + + for_each_ring_buffer_desc(rb_desc, cpu, &desc->trace_buffer_desc) { + /* Can we read nr_page_va? */ + if ((void *)rb_desc + struct_size(rb_desc, page_va, 0) > desc_end) + return false; + + /* Overflow desc? */ + if ((void *)rb_desc + struct_size(rb_desc, page_va, rb_desc->nr_page_va)= > desc_end) + return false; + + /* Overflow bpages backing memory? */ + if (nr_bpages < rb_desc->nr_page_va) + return false; + + if (cpu >=3D hyp_nr_cpus) + return false; + + if (cpu !=3D rb_desc->cpu) + return false; + + nr_bpages -=3D rb_desc->nr_page_va; + } + + return true; +} + +int __tracing_load(unsigned long desc_hva, size_t desc_size) +{ + struct hyp_trace_desc *desc =3D (struct hyp_trace_desc *)kern_hyp_va(desc= _hva); + int ret; + + ret =3D __admit_host_mem(desc, desc_size); + if (ret) + return ret; + + if (!hyp_trace_desc_validate(desc, desc_size)) + goto err_release_desc; + + hyp_spin_lock(&trace_buffer.lock); + + ret =3D hyp_trace_buffer_load(&trace_buffer, desc); + + hyp_spin_unlock(&trace_buffer.lock); + +err_release_desc: + __release_host_mem(desc, desc_size); + return ret; +} + +void __tracing_unload(void) +{ + hyp_spin_lock(&trace_buffer.lock); + hyp_trace_buffer_unload(&trace_buffer); + hyp_spin_unlock(&trace_buffer.lock); +} + +int __tracing_enable(bool enable) +{ + int cpu, ret =3D enable ? -EINVAL : 0; + + hyp_spin_lock(&trace_buffer.lock); + + if (!hyp_trace_buffer_loaded(&trace_buffer)) + goto unlock; + + for (cpu =3D 0; cpu < hyp_nr_cpus; cpu++) + simple_ring_buffer_enable_tracing(per_cpu_ptr(trace_buffer.simple_rbs, c= pu), + enable); + + ret =3D 0; + +unlock: + hyp_spin_unlock(&trace_buffer.lock); + + return ret; +} + +int __tracing_swap_reader(unsigned int cpu) +{ + int ret =3D -ENODEV; + + if (cpu >=3D hyp_nr_cpus) + return -EINVAL; + + hyp_spin_lock(&trace_buffer.lock); + + if (hyp_trace_buffer_loaded(&trace_buffer)) + ret =3D simple_ring_buffer_swap_reader_page( + per_cpu_ptr(trace_buffer.simple_rbs, cpu)); 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AJvYcCXPpHcld4UWbRp64TwMH2qosfG1+9mHrncd1fCJ09PWf7pzxJGYzzybMRvsbGE/HoS4Xlr+3SN6a5+WBhI=@vger.kernel.org X-Gm-Message-State: AOJu0Yz755+Pw9zEUpJGP3T1Aa1AdHCigAJzULv47kf4jYoDCzvWFBKQ XlIeE3dtEVpOvOfRJAggA+0OHhIGwATTvT/OTHTnEfrMMLV3W5KiEC9blwBldQWh+w9EBt8QxAP IMj4VLqQqX4IZBFgbL16hMA== X-Google-Smtp-Source: AGHT+IF3EKV05bCqj6aDz6v2j/YNOiknVT3pd4yKlcr+wsWU345kfjYAkjOacEd/MEN7AVq1it8CxLgHRzeqpBmY X-Received: from wrwt2.prod.google.com ([2002:a5d:6a42:0:b0:429:de3f:8280]) (user=vdonnefort job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6000:601:b0:429:ca7f:8d5a with SMTP id ffacd0b85a97d-42cc1d2e2e3mr42007172f8f.37.1764668214622; Tue, 02 Dec 2025 01:36:54 -0800 (PST) Date: Tue, 2 Dec 2025 09:36:17 +0000 In-Reply-To: <20251202093623.2337860-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251202093623.2337860-1-vdonnefort@google.com> X-Mailer: git-send-email 2.52.0.107.ga0afd4fd5b-goog Message-ID: <20251202093623.2337860-25-vdonnefort@google.com> Subject: [PATCH v9 24/30] KVM: arm64: Add trace remote for the nVHE/pKVM hyp From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-trace-kernel@vger.kernel.org, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, jstultz@google.com, qperret@google.com, will@kernel.org, aneesh.kumar@kernel.org, kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" In both protected and nVHE mode, the hypervisor is capable of writing events into tracefs compatible ring-buffers. Create a trace remote so the kernel can read those buffers. This currently doesn't provide any event support which will come later. Signed-off-by: Vincent Donnefort diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig index c7f50492f2cf..aad0228f24db 100644 --- a/arch/arm64/kvm/Kconfig +++ b/arch/arm64/kvm/Kconfig @@ -76,6 +76,7 @@ if NVHE_EL2_DEBUG config NVHE_EL2_TRACING bool depends on TRACING + select TRACE_REMOTE default y =20 config PKVM_DISABLE_STAGE2_ON_PANIC diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile index 3ebc0570345c..59612d2f277c 100644 --- a/arch/arm64/kvm/Makefile +++ b/arch/arm64/kvm/Makefile @@ -30,6 +30,8 @@ kvm-$(CONFIG_HW_PERF_EVENTS) +=3D pmu-emul.o pmu.o kvm-$(CONFIG_ARM64_PTR_AUTH) +=3D pauth.o kvm-$(CONFIG_PTDUMP_STAGE2_DEBUGFS) +=3D ptdump.o =20 +kvm-$(CONFIG_NVHE_EL2_TRACING) +=3D hyp_trace.o + always-y :=3D hyp_constants.h hyp-constants.s =20 define rule_gen_hyp_constants diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 7ba427f9608c..82faad681f81 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -24,6 +24,7 @@ =20 #define CREATE_TRACE_POINTS #include "trace_arm.h" +#include "hyp_trace.h" =20 #include #include @@ -2346,6 +2347,10 @@ static int __init init_subsystems(void) =20 kvm_register_perf_callbacks(NULL); =20 + err =3D kvm_hyp_trace_init(); + if (err) + kvm_err("Failed to initialize Hyp tracing\n"); + out: if (err) hyp_cpu_pm_exit(); diff --git a/arch/arm64/kvm/hyp_trace.c b/arch/arm64/kvm/hyp_trace.c new file mode 100644 index 000000000000..2866effe28ec --- /dev/null +++ b/arch/arm64/kvm/hyp_trace.c @@ -0,0 +1,219 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2025 Google LLC + * Author: Vincent Donnefort + */ + +#include +#include + +#include +#include +#include + +#include "hyp_trace.h" + +/* Access to this struct within the trace_remote_callbacks are protected b= y the trace_remote lock */ +static struct hyp_trace_buffer { + struct hyp_trace_desc *desc; + size_t desc_size; +} trace_buffer; + +static int __map_hyp(void *start, size_t size) +{ + if (is_protected_kvm_enabled()) + return 0; + + return create_hyp_mappings(start, start + size, PAGE_HYP); +} + +static int __share_page(unsigned long va) +{ + return kvm_share_hyp((void *)va, (void *)va + 1); +} + +static void __unshare_page(unsigned long va) +{ + kvm_unshare_hyp((void *)va, (void *)va + 1); +} + +static int hyp_trace_buffer_alloc_bpages_backing(struct hyp_trace_buffer *= trace_buffer, size_t size) +{ + int nr_bpages =3D (PAGE_ALIGN(size) / PAGE_SIZE) + 1; + size_t backing_size; + void *start; + + backing_size =3D PAGE_ALIGN(sizeof(struct simple_buffer_page) * nr_bpages= * + num_possible_cpus()); + + start =3D alloc_pages_exact(backing_size, GFP_KERNEL_ACCOUNT); + if (!start) + return -ENOMEM; + + trace_buffer->desc->bpages_backing_start =3D (unsigned long)start; + trace_buffer->desc->bpages_backing_size =3D backing_size; + + return __map_hyp(start, backing_size); +} + +static void hyp_trace_buffer_free_bpages_backing(struct hyp_trace_buffer *= trace_buffer) +{ + free_pages_exact((void *)trace_buffer->desc->bpages_backing_start, + trace_buffer->desc->bpages_backing_size); +} + +static void hyp_trace_buffer_unshare_hyp(struct hyp_trace_buffer *trace_bu= ffer, int last_cpu) +{ + struct ring_buffer_desc *rb_desc; + int cpu, p; + + for_each_ring_buffer_desc(rb_desc, cpu, &trace_buffer->desc->trace_buffer= _desc) { + if (cpu > last_cpu) + break; + + __share_page(rb_desc->meta_va); + for (p =3D 0; p < rb_desc->nr_page_va; p++) + __unshare_page(rb_desc->page_va[p]); + } +} + +static int hyp_trace_buffer_share_hyp(struct hyp_trace_buffer *trace_buffe= r) +{ + struct ring_buffer_desc *rb_desc; + int cpu, p, ret =3D 0; + + for_each_ring_buffer_desc(rb_desc, cpu, &trace_buffer->desc->trace_buffer= _desc) { + ret =3D __share_page(rb_desc->meta_va); + if (ret) + break; + + for (p =3D 0; p < rb_desc->nr_page_va; p++) { + ret =3D __share_page(rb_desc->page_va[p]); + if (ret) + break; + } + + if (ret) { + for (p--; p >=3D 0; p--) + __unshare_page(rb_desc->page_va[p]); + break; + } + } + + if (ret) + hyp_trace_buffer_unshare_hyp(trace_buffer, cpu--); + + return ret; +} + +static struct trace_buffer_desc *hyp_trace_load(unsigned long size, void *= priv) +{ + struct hyp_trace_buffer *trace_buffer =3D priv; + struct hyp_trace_desc *desc; + size_t desc_size; + int ret; + + if (WARN_ON(trace_buffer->desc)) + return ERR_PTR(-EINVAL); + + desc_size =3D trace_buffer_desc_size(size, num_possible_cpus()); + if (desc_size =3D=3D SIZE_MAX) + return ERR_PTR(-E2BIG); + + desc_size =3D PAGE_ALIGN(desc_size); + desc =3D (struct hyp_trace_desc *)alloc_pages_exact(desc_size, GFP_KERNEL= ); + if (!desc) + return ERR_PTR(-ENOMEM); + + ret =3D __map_hyp(desc, desc_size); + if (ret) + goto err_free_desc; + + trace_buffer->desc =3D desc; + + ret =3D hyp_trace_buffer_alloc_bpages_backing(trace_buffer, size); + if (ret) + goto err_free_desc; + + ret =3D trace_remote_alloc_buffer(&desc->trace_buffer_desc, desc_size, si= ze, + cpu_possible_mask); + if (ret) + goto err_free_backing; + + ret =3D hyp_trace_buffer_share_hyp(trace_buffer); + if (ret) + goto err_free_buffer; + + ret =3D kvm_call_hyp_nvhe(__tracing_load, (unsigned long)desc, desc_size); + if (ret) + goto err_unload_pages; + + return &desc->trace_buffer_desc; + +err_unload_pages: + hyp_trace_buffer_unshare_hyp(trace_buffer, INT_MAX); + +err_free_buffer: + trace_remote_free_buffer(&desc->trace_buffer_desc); + +err_free_backing: + hyp_trace_buffer_free_bpages_backing(trace_buffer); + +err_free_desc: + free_pages_exact(desc, desc_size); + trace_buffer->desc =3D NULL; + + return ERR_PTR(ret); +} + +static void hyp_trace_unload(struct trace_buffer_desc *desc, void *priv) +{ + struct hyp_trace_buffer *trace_buffer =3D priv; + + if (WARN_ON(desc !=3D &trace_buffer->desc->trace_buffer_desc)) + return; + + kvm_call_hyp_nvhe(__tracing_unload); + hyp_trace_buffer_unshare_hyp(trace_buffer, INT_MAX); + trace_remote_free_buffer(desc); + hyp_trace_buffer_free_bpages_backing(trace_buffer); + free_pages_exact(trace_buffer->desc, trace_buffer->desc_size); + trace_buffer->desc =3D NULL; +} + +static int hyp_trace_enable_tracing(bool enable, void *priv) +{ + return kvm_call_hyp_nvhe(__tracing_enable, enable); +} + +static int hyp_trace_swap_reader_page(unsigned int cpu, void *priv) +{ + return kvm_call_hyp_nvhe(__tracing_swap_reader, cpu); +} + +static int hyp_trace_reset(unsigned int cpu, void *priv) +{ + return 0; +} + +static int hyp_trace_enable_event(unsigned short id, bool enable, void *pr= iv) +{ + return 0; +} + +static struct trace_remote_callbacks trace_remote_callbacks =3D { + .load_trace_buffer =3D hyp_trace_load, + .unload_trace_buffer =3D hyp_trace_unload, + .enable_tracing =3D hyp_trace_enable_tracing, + .swap_reader_page =3D hyp_trace_swap_reader_page, + .reset =3D hyp_trace_reset, + .enable_event =3D hyp_trace_enable_event, +}; + +int __init kvm_hyp_trace_init(void) +{ + if (is_kernel_in_hyp_mode()) + return 0; + + return trace_remote_register("hypervisor", &trace_remote_callbacks, &trac= e_buffer, NULL, 0); +} diff --git a/arch/arm64/kvm/hyp_trace.h b/arch/arm64/kvm/hyp_trace.h new file mode 100644 index 000000000000..c991b1ec65f1 --- /dev/null +++ b/arch/arm64/kvm/hyp_trace.h @@ -0,0 +1,11 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#ifndef __ARM64_KVM_HYP_TRACE_H__ +#define __ARM64_KVM_HYP_TRACE_H__ + +#ifdef CONFIG_NVHE_EL2_TRACING +int kvm_hyp_trace_init(void); +#else +static inline int kvm_hyp_trace_init(void) { return 0; } +#endif +#endif --=20 2.52.0.107.ga0afd4fd5b-goog From nobody Wed Dec 17 06:12:58 2025 Received: from mail-wr1-f74.google.com (mail-wr1-f74.google.com [209.85.221.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 51F0B31CA54 for ; 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Tue, 02 Dec 2025 01:36:55 -0800 (PST) Date: Tue, 2 Dec 2025 09:36:18 +0000 In-Reply-To: <20251202093623.2337860-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251202093623.2337860-1-vdonnefort@google.com> X-Mailer: git-send-email 2.52.0.107.ga0afd4fd5b-goog Message-ID: <20251202093623.2337860-26-vdonnefort@google.com> Subject: [PATCH v9 25/30] KVM: arm64: Sync boot clock with the nVHE/pKVM hyp From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-trace-kernel@vger.kernel.org, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, jstultz@google.com, qperret@google.com, will@kernel.org, aneesh.kumar@kernel.org, kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort , Thomas Gleixner , Stephen Boyd , "Christopher S. Hall" , Richard Cochran Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Configure the hypervisor tracing clock with the kernel boot clock. For tracing purposes, the boot clock is interesting: it doesn't stop on suspend. However, it is corrected on a regular basis, which implies the need to re-evaluate it every once in a while. Cc: John Stultz Cc: Thomas Gleixner Cc: Stephen Boyd Cc: Christopher S. Hall Cc: Richard Cochran Signed-off-by: Vincent Donnefort diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_= asm.h index f83650a7aad9..375607c67285 100644 --- a/arch/arm64/include/asm/kvm_asm.h +++ b/arch/arm64/include/asm/kvm_asm.h @@ -93,6 +93,7 @@ enum __kvm_host_smccc_func { __KVM_HOST_SMCCC_FUNC___tracing_unload, __KVM_HOST_SMCCC_FUNC___tracing_enable, __KVM_HOST_SMCCC_FUNC___tracing_swap_reader, + __KVM_HOST_SMCCC_FUNC___tracing_update_clock, }; =20 #define DECLARE_KVM_VHE_SYM(sym) extern char sym[] diff --git a/arch/arm64/kvm/hyp/include/nvhe/trace.h b/arch/arm64/kvm/hyp/i= nclude/nvhe/trace.h index 7da8788ce527..fd641e1b1c23 100644 --- a/arch/arm64/kvm/hyp/include/nvhe/trace.h +++ b/arch/arm64/kvm/hyp/include/nvhe/trace.h @@ -11,6 +11,7 @@ int __tracing_load(unsigned long desc_va, size_t desc_siz= e); void __tracing_unload(void); int __tracing_enable(bool enable); int __tracing_swap_reader(unsigned int cpu); +void __tracing_update_clock(u32 mult, u32 shift, u64 epoch_ns, u64 epoch_c= yc); #else static inline void *tracing_reserve_entry(unsigned long length) { return N= ULL; } static inline void tracing_commit_entry(void) { } @@ -19,5 +20,6 @@ static inline int __tracing_load(unsigned long desc_va, s= ize_t desc_size) { retu static inline void __tracing_unload(void) { } static inline int __tracing_enable(bool enable) { return -ENODEV; } static inline int __tracing_swap_reader(unsigned int cpu) { return -ENODEV= ; } +static inline void __tracing_update_clock(u32 mult, u32 shift, u64 epoch_n= s, u64 epoch_cyc) { } #endif #endif diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/h= yp-main.c index 8b78b29c2069..45b8f70828de 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -613,6 +613,18 @@ static void handle___tracing_swap_reader(struct kvm_cp= u_context *host_ctxt) cpu_reg(host_ctxt, 1) =3D __tracing_swap_reader(cpu); } =20 +static void handle___tracing_update_clock(struct kvm_cpu_context *host_ctx= t) +{ + DECLARE_REG(u32, mult, host_ctxt, 1); + DECLARE_REG(u32, shift, host_ctxt, 2); + DECLARE_REG(u64, epoch_ns, host_ctxt, 3); + DECLARE_REG(u64, epoch_cyc, host_ctxt, 4); + + __tracing_update_clock(mult, shift, epoch_ns, epoch_cyc); + + cpu_reg(host_ctxt, 1) =3D 0; +} + typedef void (*hcall_t)(struct kvm_cpu_context *); =20 #define HANDLE_FUNC(x) [__KVM_HOST_SMCCC_FUNC_##x] =3D (hcall_t)handle_##x @@ -658,6 +670,7 @@ static const hcall_t host_hcall[] =3D { HANDLE_FUNC(__tracing_unload), HANDLE_FUNC(__tracing_enable), HANDLE_FUNC(__tracing_swap_reader), + HANDLE_FUNC(__tracing_update_clock), }; =20 static void handle_host_hcall(struct kvm_cpu_context *host_ctxt) diff --git a/arch/arm64/kvm/hyp/nvhe/trace.c b/arch/arm64/kvm/hyp/nvhe/trac= e.c index df9d66fcb3c9..97e9f6c1a52c 100644 --- a/arch/arm64/kvm/hyp/nvhe/trace.c +++ b/arch/arm64/kvm/hyp/nvhe/trace.c @@ -271,3 +271,19 @@ int __tracing_swap_reader(unsigned int cpu) =20 return ret; } + +void __tracing_update_clock(u32 mult, u32 shift, u64 epoch_ns, u64 epoch_c= yc) +{ + int cpu; + + /* After this loop, all CPUs are observing the new bank... */ + for (cpu =3D 0; cpu < hyp_nr_cpus; cpu++) { + struct simple_rb_per_cpu *simple_rb =3D per_cpu_ptr(trace_buffer.simple_= rbs, cpu); + + while (READ_ONCE(simple_rb->status) =3D=3D SIMPLE_RB_WRITING) + ; + } + + /* ...we can now override the old one and swap. */ + trace_clock_update(mult, shift, epoch_ns, epoch_cyc); +} diff --git a/arch/arm64/kvm/hyp_trace.c b/arch/arm64/kvm/hyp_trace.c index 2866effe28ec..1e5fc27f0e9d 100644 --- a/arch/arm64/kvm/hyp_trace.c +++ b/arch/arm64/kvm/hyp_trace.c @@ -4,15 +4,133 @@ * Author: Vincent Donnefort */ =20 +#include #include +#include #include =20 +#include #include #include #include =20 #include "hyp_trace.h" =20 +/* Same 10min used by clocksource when width is more than 32-bits */ +#define CLOCK_MAX_CONVERSION_S 600 +/* + * Time to give for the clock init. Long enough to get a good mult/shift + * estimation. Short enough to not delay the tracing start too much. + */ +#define CLOCK_INIT_MS 100 +/* + * Time between clock checks. Must be small enough to catch clock deviatio= n when + * it is still tiny. + */ +#define CLOCK_UPDATE_MS 500 + +static struct hyp_trace_clock { + u64 cycles; + u64 cyc_overflow64; + u64 boot; + u32 mult; + u32 shift; + struct delayed_work work; + struct completion ready; + struct mutex lock; + bool running; +} hyp_clock; + +static void __hyp_clock_work(struct work_struct *work) +{ + struct delayed_work *dwork =3D to_delayed_work(work); + struct hyp_trace_clock *hyp_clock; + struct system_time_snapshot snap; + u64 rate, delta_cycles; + u64 boot, delta_boot; + + hyp_clock =3D container_of(dwork, struct hyp_trace_clock, work); + + ktime_get_snapshot(&snap); + boot =3D ktime_to_ns(snap.boot); + + delta_boot =3D boot - hyp_clock->boot; + delta_cycles =3D snap.cycles - hyp_clock->cycles; + + /* Compare hyp clock with the kernel boot clock */ + if (hyp_clock->mult) { + u64 err, cur =3D delta_cycles; + + if (WARN_ON_ONCE(cur >=3D hyp_clock->cyc_overflow64)) { + __uint128_t tmp =3D (__uint128_t)cur * hyp_clock->mult; + + cur =3D tmp >> hyp_clock->shift; + } else { + cur *=3D hyp_clock->mult; + cur >>=3D hyp_clock->shift; + } + cur +=3D hyp_clock->boot; + + err =3D abs_diff(cur, boot); + /* No deviation, only update epoch if necessary */ + if (!err) { + if (delta_cycles >=3D (hyp_clock->cyc_overflow64 >> 1)) + goto fast_forward; + + goto resched; + } + + /* Warn if the error is above tracing precision (1us) */ + if (err > NSEC_PER_USEC) + pr_warn_ratelimited("hyp trace clock off by %lluus\n", + err / NSEC_PER_USEC); + } + + rate =3D div64_u64(delta_cycles * NSEC_PER_SEC, delta_boot); + + clocks_calc_mult_shift(&hyp_clock->mult, &hyp_clock->shift, + rate, NSEC_PER_SEC, CLOCK_MAX_CONVERSION_S); + + /* Add a comfortable 50% margin */ + hyp_clock->cyc_overflow64 =3D (U64_MAX / hyp_clock->mult) >> 1; + +fast_forward: + hyp_clock->cycles =3D snap.cycles; + hyp_clock->boot =3D boot; + kvm_call_hyp_nvhe(__tracing_update_clock, hyp_clock->mult, + hyp_clock->shift, hyp_clock->boot, hyp_clock->cycles); + complete(&hyp_clock->ready); + +resched: + schedule_delayed_work(&hyp_clock->work, + msecs_to_jiffies(CLOCK_UPDATE_MS)); +} + +static void hyp_trace_clock_enable(struct hyp_trace_clock *hyp_clock, bool= enable) +{ + struct system_time_snapshot snap; + + if (hyp_clock->running =3D=3D enable) + return; + + if (!enable) { + cancel_delayed_work_sync(&hyp_clock->work); + hyp_clock->running =3D false; + } + + ktime_get_snapshot(&snap); + + hyp_clock->boot =3D ktime_to_ns(snap.boot); + hyp_clock->cycles =3D snap.cycles; + hyp_clock->mult =3D 0; + + init_completion(&hyp_clock->ready); + INIT_DELAYED_WORK(&hyp_clock->work, __hyp_clock_work); + schedule_delayed_work(&hyp_clock->work, msecs_to_jiffies(CLOCK_INIT_MS)); + wait_for_completion(&hyp_clock->ready); + hyp_clock->running =3D true; +} + /* Access to this struct within the trace_remote_callbacks are protected b= y the trace_remote lock */ static struct hyp_trace_buffer { struct hyp_trace_desc *desc; @@ -183,6 +301,8 @@ static void hyp_trace_unload(struct trace_buffer_desc *= desc, void *priv) =20 static int hyp_trace_enable_tracing(bool enable, void *priv) { + hyp_trace_clock_enable(&hyp_clock, enable); + return kvm_call_hyp_nvhe(__tracing_enable, enable); } =20 @@ -201,7 +321,22 @@ static int hyp_trace_enable_event(unsigned short id, b= ool enable, void *priv) return 0; } =20 +static int hyp_trace_clock_show(struct seq_file *m, void *v) +{ + seq_puts(m, "[boot]\n"); + + return 0; +} +DEFINE_SHOW_ATTRIBUTE(hyp_trace_clock); + +static int hyp_trace_init_tracefs(struct dentry *d, void *priv) +{ + return tracefs_create_file("trace_clock", 0440, d, NULL, &hyp_trace_clock= _fops) ? + 0 : -ENOMEM; +} + static struct trace_remote_callbacks trace_remote_callbacks =3D { + .init =3D hyp_trace_init_tracefs, .load_trace_buffer =3D hyp_trace_load, .unload_trace_buffer =3D hyp_trace_unload, .enable_tracing =3D hyp_trace_enable_tracing, @@ -212,8 +347,22 @@ static struct trace_remote_callbacks trace_remote_call= backs =3D { =20 int __init kvm_hyp_trace_init(void) { + int cpu; + if (is_kernel_in_hyp_mode()) return 0; =20 +#ifdef CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND + for_each_possible_cpu(cpu) { + const struct arch_timer_erratum_workaround *wa =3D + per_cpu(timer_unstable_counter_workaround, cpu); 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charset="utf-8" Make the hypervisor reset either the whole tracing buffer or a specific ring-buffer, on remotes/hypervisor/trace or per_cpu//trace write access. Signed-off-by: Vincent Donnefort diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_= asm.h index 375607c67285..a28b072125ec 100644 --- a/arch/arm64/include/asm/kvm_asm.h +++ b/arch/arm64/include/asm/kvm_asm.h @@ -94,6 +94,7 @@ enum __kvm_host_smccc_func { __KVM_HOST_SMCCC_FUNC___tracing_enable, __KVM_HOST_SMCCC_FUNC___tracing_swap_reader, __KVM_HOST_SMCCC_FUNC___tracing_update_clock, + __KVM_HOST_SMCCC_FUNC___tracing_reset, }; =20 #define DECLARE_KVM_VHE_SYM(sym) extern char sym[] diff --git a/arch/arm64/kvm/hyp/include/nvhe/trace.h b/arch/arm64/kvm/hyp/i= nclude/nvhe/trace.h index fd641e1b1c23..44912869d184 100644 --- a/arch/arm64/kvm/hyp/include/nvhe/trace.h +++ b/arch/arm64/kvm/hyp/include/nvhe/trace.h @@ -12,6 +12,7 @@ void __tracing_unload(void); int __tracing_enable(bool enable); int __tracing_swap_reader(unsigned int cpu); void __tracing_update_clock(u32 mult, u32 shift, u64 epoch_ns, u64 epoch_c= yc); +int __tracing_reset(unsigned int cpu); #else static inline void *tracing_reserve_entry(unsigned long length) { return N= ULL; } static inline void tracing_commit_entry(void) { } @@ -21,5 +22,6 @@ static inline void __tracing_unload(void) { } static inline int __tracing_enable(bool enable) { return -ENODEV; } static inline int __tracing_swap_reader(unsigned int cpu) { return -ENODEV= ; } static inline void __tracing_update_clock(u32 mult, u32 shift, u64 epoch_n= s, u64 epoch_cyc) { } +static inline int __tracing_reset(unsigned int cpu) { return -ENODEV; } #endif #endif diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/h= yp-main.c index 45b8f70828de..f92e82cbfcb4 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -625,6 +625,13 @@ static void handle___tracing_update_clock(struct kvm_c= pu_context *host_ctxt) cpu_reg(host_ctxt, 1) =3D 0; } =20 +static void handle___tracing_reset(struct kvm_cpu_context *host_ctxt) +{ + DECLARE_REG(unsigned int, cpu, host_ctxt, 1); + + cpu_reg(host_ctxt, 1) =3D __tracing_reset(cpu); +} + typedef void (*hcall_t)(struct kvm_cpu_context *); =20 #define HANDLE_FUNC(x) [__KVM_HOST_SMCCC_FUNC_##x] =3D (hcall_t)handle_##x @@ -671,6 +678,7 @@ static const hcall_t host_hcall[] =3D { HANDLE_FUNC(__tracing_enable), HANDLE_FUNC(__tracing_swap_reader), HANDLE_FUNC(__tracing_update_clock), + HANDLE_FUNC(__tracing_reset), }; =20 static void handle_host_hcall(struct kvm_cpu_context *host_ctxt) diff --git a/arch/arm64/kvm/hyp/nvhe/trace.c b/arch/arm64/kvm/hyp/nvhe/trac= e.c index 97e9f6c1a52c..93475cc36640 100644 --- a/arch/arm64/kvm/hyp/nvhe/trace.c +++ b/arch/arm64/kvm/hyp/nvhe/trace.c @@ -287,3 +287,20 @@ void __tracing_update_clock(u32 mult, u32 shift, u64 e= poch_ns, u64 epoch_cyc) /* ...we can now override the old one and swap. */ trace_clock_update(mult, shift, epoch_ns, epoch_cyc); } + +int __tracing_reset(unsigned int cpu) +{ + int ret =3D -ENODEV; + + if (cpu >=3D hyp_nr_cpus) + return -EINVAL; + + hyp_spin_lock(&trace_buffer.lock); + + if (hyp_trace_buffer_loaded(&trace_buffer)) + ret =3D simple_ring_buffer_reset(per_cpu_ptr(trace_buffer.simple_rbs, cp= u)); 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Tue, 02 Dec 2025 01:36:57 -0800 (PST) Date: Tue, 2 Dec 2025 09:36:20 +0000 In-Reply-To: <20251202093623.2337860-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251202093623.2337860-1-vdonnefort@google.com> X-Mailer: git-send-email 2.52.0.107.ga0afd4fd5b-goog Message-ID: <20251202093623.2337860-28-vdonnefort@google.com> Subject: [PATCH v9 27/30] KVM: arm64: Add event support to the nVHE/pKVM hyp and trace remote From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-trace-kernel@vger.kernel.org, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, jstultz@google.com, qperret@google.com, will@kernel.org, aneesh.kumar@kernel.org, kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Allow the creation of hypervisor and trace remote events with a single macro HYP_EVENT(). That macro expands in the kernel side to add all the required declarations (based on REMOTE_EVENT()) as well as in the hypervisor side to create the trace_() function. Signed-off-by: Vincent Donnefort diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_= asm.h index a28b072125ec..37c015b54ff6 100644 --- a/arch/arm64/include/asm/kvm_asm.h +++ b/arch/arm64/include/asm/kvm_asm.h @@ -95,6 +95,7 @@ enum __kvm_host_smccc_func { __KVM_HOST_SMCCC_FUNC___tracing_swap_reader, __KVM_HOST_SMCCC_FUNC___tracing_update_clock, __KVM_HOST_SMCCC_FUNC___tracing_reset, + __KVM_HOST_SMCCC_FUNC___tracing_enable_event, }; =20 #define DECLARE_KVM_VHE_SYM(sym) extern char sym[] diff --git a/arch/arm64/include/asm/kvm_define_hypevents.h b/arch/arm64/inc= lude/asm/kvm_define_hypevents.h new file mode 100644 index 000000000000..77d6790252a6 --- /dev/null +++ b/arch/arm64/include/asm/kvm_define_hypevents.h @@ -0,0 +1,16 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#define REMOTE_EVENT_INCLUDE_FILE arch/arm64/include/asm/kvm_hypevents.h + +#define REMOTE_EVENT_SECTION "_hyp_events" + +#define HE_STRUCT(__args) __args +#define HE_PRINTK(__args...) __args +#define he_field re_field + +#define HYP_EVENT(__name, __proto, __struct, __assign, __printk) \ + REMOTE_EVENT(__name, 0, RE_STRUCT(__struct), RE_PRINTK(__printk)) + +#define HYP_EVENT_MULTI_READ +#include +#undef HYP_EVENT_MULTI_READ diff --git a/arch/arm64/include/asm/kvm_hypevents.h b/arch/arm64/include/as= m/kvm_hypevents.h new file mode 100644 index 000000000000..d6e033c96c52 --- /dev/null +++ b/arch/arm64/include/asm/kvm_hypevents.h @@ -0,0 +1,10 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#if !defined(__ARM64_KVM_HYPEVENTS_H_) || defined(HYP_EVENT_MULTI_READ) +#define __ARM64_KVM_HYPEVENTS_H_ + +#ifdef __KVM_NVHE_HYPERVISOR__ +#include +#endif + +#endif diff --git a/arch/arm64/include/asm/kvm_hyptrace.h b/arch/arm64/include/asm= /kvm_hyptrace.h index 9c30a479bc36..de133b735f72 100644 --- a/arch/arm64/include/asm/kvm_hyptrace.h +++ b/arch/arm64/include/asm/kvm_hyptrace.h @@ -10,4 +10,17 @@ struct hyp_trace_desc { struct trace_buffer_desc trace_buffer_desc; =20 }; + +struct hyp_event_id { + unsigned short id; + atomic_t enabled; +}; + +extern struct remote_event __hyp_events_start[]; +extern struct remote_event __hyp_events_end[]; + +/* hyp_event section used by the hypervisor */ +extern struct hyp_event_id __hyp_event_ids_start[]; +extern struct hyp_event_id __hyp_event_ids_end[]; + #endif diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h index 5369763606e7..872ab7897fce 100644 --- a/arch/arm64/kernel/image-vars.h +++ b/arch/arm64/kernel/image-vars.h @@ -137,6 +137,10 @@ KVM_NVHE_ALIAS(__hyp_data_start); KVM_NVHE_ALIAS(__hyp_data_end); KVM_NVHE_ALIAS(__hyp_rodata_start); KVM_NVHE_ALIAS(__hyp_rodata_end); +#ifdef CONFIG_NVHE_EL2_TRACING +KVM_NVHE_ALIAS(__hyp_event_ids_start); +KVM_NVHE_ALIAS(__hyp_event_ids_end); +#endif =20 /* pKVM static key */ KVM_NVHE_ALIAS(kvm_protected_mode_initialized); diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.ld= s.S index ad6133b89e7a..273a461c6076 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -13,12 +13,23 @@ *(__kvm_ex_table) \ __stop___kvm_ex_table =3D .; =20 +#ifdef CONFIG_NVHE_EL2_TRACING +#define HYPERVISOR_EVENT_IDS \ + . =3D ALIGN(PAGE_SIZE); \ + __hyp_event_ids_start =3D .; \ + *(HYP_SECTION_NAME(.event_ids)) \ + __hyp_event_ids_end =3D .; +#else +#define HYPERVISOR_EVENT_IDS +#endif + #define HYPERVISOR_RODATA_SECTIONS \ HYP_SECTION_NAME(.rodata) : { \ . =3D ALIGN(PAGE_SIZE); \ __hyp_rodata_start =3D .; \ *(HYP_SECTION_NAME(.data..ro_after_init)) \ *(HYP_SECTION_NAME(.rodata)) \ + HYPERVISOR_EVENT_IDS \ . =3D ALIGN(PAGE_SIZE); \ __hyp_rodata_end =3D .; \ } @@ -307,6 +318,13 @@ SECTIONS =20 HYPERVISOR_DATA_SECTION =20 +#ifdef CONFIG_NVHE_EL2_TRACING + .data.hyp_events : { + __hyp_events_start =3D .; + *(SORT(_hyp_events.*)) + __hyp_events_end =3D .; + } +#endif /* * Data written with the MMU off but read with the MMU on requires * cache lines to be invalidated, discarding up to a Cache Writeback diff --git a/arch/arm64/kvm/hyp/include/nvhe/define_events.h b/arch/arm64/k= vm/hyp/include/nvhe/define_events.h new file mode 100644 index 000000000000..776d4c6cb702 --- /dev/null +++ b/arch/arm64/kvm/hyp/include/nvhe/define_events.h @@ -0,0 +1,14 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#undef HYP_EVENT +#define HYP_EVENT(__name, __proto, __struct, __assign, __printk) \ + struct hyp_event_id hyp_event_id_##__name \ + __section(".hyp.event_ids."#__name) =3D { \ + .enabled =3D ATOMIC_INIT(0), \ + } + +#define HYP_EVENT_MULTI_READ +#include +#undef HYP_EVENT_MULTI_READ + +#undef HYP_EVENT diff --git a/arch/arm64/kvm/hyp/include/nvhe/trace.h b/arch/arm64/kvm/hyp/i= nclude/nvhe/trace.h index 44912869d184..802a18b77c56 100644 --- a/arch/arm64/kvm/hyp/include/nvhe/trace.h +++ b/arch/arm64/kvm/hyp/include/nvhe/trace.h @@ -1,9 +1,36 @@ /* SPDX-License-Identifier: GPL-2.0-only */ #ifndef __ARM64_KVM_HYP_NVHE_TRACE_H #define __ARM64_KVM_HYP_NVHE_TRACE_H + +#include + #include =20 +#define HE_PROTO(__args...) __args +#define HE_ASSIGN(__args...) __args +#define HE_STRUCT RE_STRUCT +#define he_field re_field + #ifdef CONFIG_NVHE_EL2_TRACING + +#define HYP_EVENT(__name, __proto, __struct, __assign, __printk) \ + REMOTE_EVENT_FORMAT(__name, __struct); \ + extern struct hyp_event_id hyp_event_id_##__name; \ + static __always_inline void trace_##__name(__proto) \ + { \ + struct remote_event_format_##__name *__entry; \ + size_t length =3D sizeof(*__entry); \ + \ + if (!atomic_read(&hyp_event_id_##__name.enabled)) \ + return; \ + __entry =3D tracing_reserve_entry(length); \ + if (!__entry) \ + return; \ + __entry->hdr.id =3D hyp_event_id_##__name.id; \ + __assign \ + tracing_commit_entry(); \ + } + void *tracing_reserve_entry(unsigned long length); void tracing_commit_entry(void); =20 @@ -13,9 +40,12 @@ int __tracing_enable(bool enable); int __tracing_swap_reader(unsigned int cpu); void __tracing_update_clock(u32 mult, u32 shift, u64 epoch_ns, u64 epoch_c= yc); int __tracing_reset(unsigned int cpu); +int __tracing_enable_event(unsigned short id, bool enable); #else static inline void *tracing_reserve_entry(unsigned long length) { return N= ULL; } static inline void tracing_commit_entry(void) { } +#define HYP_EVENT(__name, __proto, __struct, __assign, __printk) \ + static inline void trace_##__name(__proto) {} =20 static inline int __tracing_load(unsigned long desc_va, size_t desc_size) = { return -ENODEV; } static inline void __tracing_unload(void) { } @@ -23,5 +53,6 @@ static inline int __tracing_enable(bool enable) { return = -ENODEV; } static inline int __tracing_swap_reader(unsigned int cpu) { return -ENODEV= ; } static inline void __tracing_update_clock(u32 mult, u32 shift, u64 epoch_n= s, u64 epoch_cyc) { } static inline int __tracing_reset(unsigned int cpu) { return -ENODEV; } +static inline int __tracing_enable_event(unsigned short id, bool enable) = { return -ENODEV; } #endif #endif diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Mak= efile index f1840628d2d6..143d55ec7298 100644 --- a/arch/arm64/kvm/hyp/nvhe/Makefile +++ b/arch/arm64/kvm/hyp/nvhe/Makefile @@ -29,7 +29,7 @@ hyp-obj-y +=3D ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cp= uif-proxy.o ../entry.o \ ../fpsimd.o ../hyp-entry.o ../exception.o ../pgtable.o hyp-obj-y +=3D ../../../kernel/smccc-call.o hyp-obj-$(CONFIG_LIST_HARDENED) +=3D list_debug.o -hyp-obj-$(CONFIG_NVHE_EL2_TRACING) +=3D clock.o trace.o +hyp-obj-$(CONFIG_NVHE_EL2_TRACING) +=3D clock.o trace.o events.o hyp-obj-y +=3D $(lib-objs) =20 # Path to simple_ring_buffer.c diff --git a/arch/arm64/kvm/hyp/nvhe/events.c b/arch/arm64/kvm/hyp/nvhe/eve= nts.c new file mode 100644 index 000000000000..add9383aadb5 --- /dev/null +++ b/arch/arm64/kvm/hyp/nvhe/events.c @@ -0,0 +1,25 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2025 Google LLC + * Author: Vincent Donnefort + */ + +#include +#include + +#include + +int __tracing_enable_event(unsigned short id, bool enable) +{ + struct hyp_event_id *event_id =3D &__hyp_event_ids_start[id]; + atomic_t *enabled; + + if (event_id >=3D __hyp_event_ids_end) + return -EINVAL; + + enabled =3D hyp_fixmap_map(__hyp_pa(&event_id->enabled)); + atomic_set(enabled, enable); + hyp_fixmap_unmap(); + + return 0; +} diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/h= yp-main.c index f92e82cbfcb4..446603cdad7b 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -632,6 +632,14 @@ static void handle___tracing_reset(struct kvm_cpu_cont= ext *host_ctxt) cpu_reg(host_ctxt, 1) =3D __tracing_reset(cpu); } =20 +static void handle___tracing_enable_event(struct kvm_cpu_context *host_ctx= t) +{ + DECLARE_REG(unsigned short, id, host_ctxt, 1); + DECLARE_REG(bool, enable, host_ctxt, 2); + + cpu_reg(host_ctxt, 1) =3D __tracing_enable_event(id, enable); +} + typedef void (*hcall_t)(struct kvm_cpu_context *); =20 #define HANDLE_FUNC(x) [__KVM_HOST_SMCCC_FUNC_##x] =3D (hcall_t)handle_##x @@ -679,6 +687,7 @@ static const hcall_t host_hcall[] =3D { HANDLE_FUNC(__tracing_swap_reader), HANDLE_FUNC(__tracing_update_clock), HANDLE_FUNC(__tracing_reset), + HANDLE_FUNC(__tracing_enable_event), }; =20 static void handle_host_hcall(struct kvm_cpu_context *host_ctxt) diff --git a/arch/arm64/kvm/hyp/nvhe/hyp.lds.S b/arch/arm64/kvm/hyp/nvhe/hy= p.lds.S index d724f6d69302..7a02837203d1 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp.lds.S +++ b/arch/arm64/kvm/hyp/nvhe/hyp.lds.S @@ -16,6 +16,12 @@ SECTIONS { HYP_SECTION(.text) HYP_SECTION(.data..ro_after_init) HYP_SECTION(.rodata) +#ifdef CONFIG_NVHE_EL2_TRACING + . =3D ALIGN(PAGE_SIZE); + BEGIN_HYP_SECTION(.event_ids) + *(SORT(.hyp.event_ids.*)) + END_HYP_SECTION +#endif =20 /* * .hyp..data..percpu needs to be page aligned to maintain the same diff --git a/arch/arm64/kvm/hyp_trace.c b/arch/arm64/kvm/hyp_trace.c index 09bc192e3514..0144cd26703e 100644 --- a/arch/arm64/kvm/hyp_trace.c +++ b/arch/arm64/kvm/hyp_trace.c @@ -318,6 +318,25 @@ static int hyp_trace_reset(unsigned int cpu, void *pri= v) =20 static int hyp_trace_enable_event(unsigned short id, bool enable, void *pr= iv) { + struct hyp_event_id *event_id =3D lm_alias(&__hyp_event_ids_start[id]); + struct page *page; + atomic_t *enabled; + void *map; + + if (is_protected_kvm_enabled()) + return kvm_call_hyp_nvhe(__tracing_enable_event, id, enable); + + enabled =3D &event_id->enabled; + page =3D virt_to_page(enabled); + map =3D vmap(&page, 1, VM_MAP, PAGE_KERNEL); + if (!map) + return -ENOMEM; + + enabled =3D map + offset_in_page(enabled); + atomic_set(enabled, enable); + + vunmap(map); + return 0; } =20 @@ -345,6 +364,19 @@ static struct trace_remote_callbacks trace_remote_call= backs =3D { .enable_event =3D hyp_trace_enable_event, }; =20 +#include + +static void __init hyp_trace_init_events(void) +{ + struct hyp_event_id *hyp_event_id =3D __hyp_event_ids_start; + struct remote_event *event =3D __hyp_events_start; + int id =3D 0; + + /* Events on both sides hypervisor are sorted */ + for (; event < __hyp_events_end; event++, hyp_event_id++, id++) + event->id =3D hyp_event_id->id =3D id; +} + int __init kvm_hyp_trace_init(void) { int cpu; @@ -364,5 +396,8 @@ int __init kvm_hyp_trace_init(void) } #endif =20 - return trace_remote_register("hypervisor", &trace_remote_callbacks, &trac= e_buffer, NULL, 0); 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AJvYcCU0cu0XNPns2r8BWkDjTEg3R27slCjfZRj/Xoz46ob09a0XUGrsBVCGiOHVj6aXiT+owVERx6Bcs45gG2o=@vger.kernel.org X-Gm-Message-State: AOJu0Yz4A1M2iE1wLGBF2UYgZrZtNzY+1TL7cQK5KEqPLGb38FLi5KC5 Z9ynATeC9OaU3BwCxITCpyb/ecIMigSAHMevdYNhxtwjLk9dLmPzJfztchiBYwio8AKW9Rjx0mc evrAZ8SYZZjJv+mRSo1QAoA== X-Google-Smtp-Source: AGHT+IEL2xhvrCzDgCDm5FVZKKsD3CuAyvFPc5ZvmKGBb3Dxn5ejyZKUewPz1pQbPvJJW9wUyfsgfPIcNBKbz1wU X-Received: from edt19.prod.google.com ([2002:a05:6402:4553:b0:647:6679:ad0d]) (user=vdonnefort job=prod-delivery.src-stubby-dispatcher) by 2002:a17:906:fe4c:b0:b76:694a:b0ca with SMTP id a640c23a62f3a-b76715ebba8mr4540359266b.27.1764668218802; Tue, 02 Dec 2025 01:36:58 -0800 (PST) Date: Tue, 2 Dec 2025 09:36:21 +0000 In-Reply-To: <20251202093623.2337860-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251202093623.2337860-1-vdonnefort@google.com> X-Mailer: git-send-email 2.52.0.107.ga0afd4fd5b-goog Message-ID: <20251202093623.2337860-29-vdonnefort@google.com> Subject: [PATCH v9 28/30] KVM: arm64: Add hyp_enter/hyp_exit events to nVHE/pKVM hyp From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-trace-kernel@vger.kernel.org, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, jstultz@google.com, qperret@google.com, will@kernel.org, aneesh.kumar@kernel.org, kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The hyp_enter and hyp_exit events are logged by the hypervisor any time it is entered and exited. Signed-off-by: Vincent Donnefort diff --git a/arch/arm64/include/asm/kvm_hypevents.h b/arch/arm64/include/as= m/kvm_hypevents.h index d6e033c96c52..268b3cd7a1b2 100644 --- a/arch/arm64/include/asm/kvm_hypevents.h +++ b/arch/arm64/include/asm/kvm_hypevents.h @@ -7,4 +7,39 @@ #include #endif =20 +#ifndef __HYP_ENTER_EXIT_REASON +#define __HYP_ENTER_EXIT_REASON +enum hyp_enter_exit_reason { + HYP_REASON_SMC, + HYP_REASON_HVC, + HYP_REASON_PSCI, + HYP_REASON_HOST_ABORT, + HYP_REASON_GUEST_EXIT, + HYP_REASON_ERET_HOST, + HYP_REASON_ERET_GUEST, + HYP_REASON_UNKNOWN /* Must be last */ +}; +#endif + +HYP_EVENT(hyp_enter, + HE_PROTO(u8 reason), + HE_STRUCT( + he_field(u8, reason) + ), + HE_ASSIGN( + __entry->reason =3D reason; + ), + HE_PRINTK("reason=3D%s", __hyp_enter_exit_reason_str(__entry->reason)) +); + +HYP_EVENT(hyp_exit, + HE_PROTO(u8 reason), + HE_STRUCT( + he_field(u8, reason) + ), + HE_ASSIGN( + __entry->reason =3D reason; + ), + HE_PRINTK("reason=3D%s", __hyp_enter_exit_reason_str(__entry->reason)) +); #endif diff --git a/arch/arm64/kvm/hyp/include/nvhe/arm-smccc.h b/arch/arm64/kvm/h= yp/include/nvhe/arm-smccc.h new file mode 100644 index 000000000000..7cd0f701f3c9 --- /dev/null +++ b/arch/arm64/kvm/hyp/include/nvhe/arm-smccc.h @@ -0,0 +1,23 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef __ARM64_KVM_HYP_NVHE_ARM_SMCCC_H__ +#define __ARM64_KVM_HYP_NVHE_ARM_SMCCC_H__ + +#include + +#include + +#define hyp_smccc_1_1_smc(...) \ + do { \ + trace_hyp_exit(HYP_REASON_SMC); \ + arm_smccc_1_1_smc(__VA_ARGS__); \ + trace_hyp_enter(HYP_REASON_SMC); \ + } while (0) + +#define hyp_smccc_1_2_smc(...) \ + do { \ + trace_hyp_exit(HYP_REASON_SMC); \ + arm_smccc_1_2_smc(__VA_ARGS__); \ + trace_hyp_enter(HYP_REASON_SMC); \ + } while (0) + +#endif /* __ARM64_KVM_HYP_NVHE_ARM_SMCCC_H__ */ diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c index 58b7d0c477d7..73d79f9de850 100644 --- a/arch/arm64/kvm/hyp/nvhe/ffa.c +++ b/arch/arm64/kvm/hyp/nvhe/ffa.c @@ -26,10 +26,10 @@ * the duration and are therefore serialised. */ =20 -#include #include #include =20 +#include #include #include #include @@ -147,7 +147,7 @@ static int ffa_map_hyp_buffers(u64 ffa_page_count) { struct arm_smccc_1_2_regs res; =20 - arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) { + hyp_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) { .a0 =3D FFA_FN64_RXTX_MAP, .a1 =3D hyp_virt_to_phys(hyp_buffers.tx), .a2 =3D hyp_virt_to_phys(hyp_buffers.rx), @@ -161,7 +161,7 @@ static int ffa_unmap_hyp_buffers(void) { struct arm_smccc_1_2_regs res; =20 - arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) { + hyp_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) { .a0 =3D FFA_RXTX_UNMAP, .a1 =3D HOST_FFA_ID, }, &res); @@ -172,7 +172,7 @@ static int ffa_unmap_hyp_buffers(void) static void ffa_mem_frag_tx(struct arm_smccc_1_2_regs *res, u32 handle_lo, u32 handle_hi, u32 fraglen, u32 endpoint_id) { - arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) { + hyp_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) { .a0 =3D FFA_MEM_FRAG_TX, .a1 =3D handle_lo, .a2 =3D handle_hi, @@ -184,7 +184,7 @@ static void ffa_mem_frag_tx(struct arm_smccc_1_2_regs *= res, u32 handle_lo, static void ffa_mem_frag_rx(struct arm_smccc_1_2_regs *res, u32 handle_lo, u32 handle_hi, u32 fragoff) { - arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) { + hyp_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) { .a0 =3D FFA_MEM_FRAG_RX, .a1 =3D handle_lo, .a2 =3D handle_hi, @@ -196,7 +196,7 @@ static void ffa_mem_frag_rx(struct arm_smccc_1_2_regs *= res, u32 handle_lo, static void ffa_mem_xfer(struct arm_smccc_1_2_regs *res, u64 func_id, u32 = len, u32 fraglen) { - arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) { + hyp_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) { .a0 =3D func_id, .a1 =3D len, .a2 =3D fraglen, @@ -206,7 +206,7 @@ static void ffa_mem_xfer(struct arm_smccc_1_2_regs *res= , u64 func_id, u32 len, static void ffa_mem_reclaim(struct arm_smccc_1_2_regs *res, u32 handle_lo, u32 handle_hi, u32 flags) { - arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) { + hyp_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) { .a0 =3D FFA_MEM_RECLAIM, .a1 =3D handle_lo, .a2 =3D handle_hi, @@ -216,7 +216,7 @@ static void ffa_mem_reclaim(struct arm_smccc_1_2_regs *= res, u32 handle_lo, =20 static void ffa_retrieve_req(struct arm_smccc_1_2_regs *res, u32 len) { - arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) { + hyp_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) { .a0 =3D FFA_FN64_MEM_RETRIEVE_REQ, .a1 =3D len, .a2 =3D len, @@ -225,7 +225,7 @@ static void ffa_retrieve_req(struct arm_smccc_1_2_regs = *res, u32 len) =20 static void ffa_rx_release(struct arm_smccc_1_2_regs *res) { - arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) { + hyp_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) { .a0 =3D FFA_RX_RELEASE, }, res); } @@ -728,7 +728,7 @@ static int hyp_ffa_post_init(void) size_t min_rxtx_sz; struct arm_smccc_1_2_regs res; =20 - arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs){ + hyp_smccc_1_2_smc(&(struct arm_smccc_1_2_regs){ .a0 =3D FFA_ID_GET, }, &res); if (res.a0 !=3D FFA_SUCCESS) @@ -737,7 +737,7 @@ static int hyp_ffa_post_init(void) if (res.a2 !=3D HOST_FFA_ID) return -EINVAL; =20 - arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs){ + hyp_smccc_1_2_smc(&(struct arm_smccc_1_2_regs){ .a0 =3D FFA_FEATURES, .a1 =3D FFA_FN64_RXTX_MAP, }, &res); @@ -788,7 +788,7 @@ static void do_ffa_version(struct arm_smccc_1_2_regs *r= es, * first if TEE supports it. */ if (FFA_MINOR_VERSION(ffa_req_version) < FFA_MINOR_VERSION(hyp_ffa_versio= n)) { - arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) { + hyp_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) { .a0 =3D FFA_VERSION, .a1 =3D ffa_req_version, }, res); @@ -824,7 +824,7 @@ static void do_ffa_part_get(struct arm_smccc_1_2_regs *= res, goto out_unlock; } =20 - arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) { + hyp_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) { .a0 =3D FFA_PARTITION_INFO_GET, .a1 =3D uuid0, .a2 =3D uuid1, @@ -939,7 +939,7 @@ int hyp_ffa_init(void *pages) if (kvm_host_psci_config.smccc_version < ARM_SMCCC_VERSION_1_2) return 0; =20 - arm_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) { + hyp_smccc_1_2_smc(&(struct arm_smccc_1_2_regs) { .a0 =3D FFA_VERSION, .a1 =3D FFA_VERSION_1_2, }, &res); diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/h= yp-main.c index 446603cdad7b..ffda4850022f 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -12,6 +12,7 @@ #include #include #include +#include #include =20 #include @@ -728,7 +729,9 @@ static void handle_host_hcall(struct kvm_cpu_context *h= ost_ctxt) =20 static void default_host_smc_handler(struct kvm_cpu_context *host_ctxt) { + trace_hyp_exit(HYP_REASON_SMC); __kvm_hyp_host_forward_smc(host_ctxt); + trace_hyp_enter(HYP_REASON_SMC); } =20 static void handle_host_smc(struct kvm_cpu_context *host_ctxt) @@ -752,18 +755,24 @@ void handle_trap(struct kvm_cpu_context *host_ctxt) { u64 esr =3D read_sysreg_el2(SYS_ESR); =20 + switch (ESR_ELx_EC(esr)) { case ESR_ELx_EC_HVC64: + trace_hyp_enter(HYP_REASON_HVC); handle_host_hcall(host_ctxt); break; case ESR_ELx_EC_SMC64: + trace_hyp_enter(HYP_REASON_SMC); handle_host_smc(host_ctxt); break; case ESR_ELx_EC_IABT_LOW: case ESR_ELx_EC_DABT_LOW: + trace_hyp_enter(HYP_REASON_HOST_ABORT); handle_host_mem_abort(host_ctxt); break; default: BUG(); } + + trace_hyp_exit(HYP_REASON_ERET_HOST); } diff --git a/arch/arm64/kvm/hyp/nvhe/psci-relay.c b/arch/arm64/kvm/hyp/nvhe= /psci-relay.c index c3e196fb8b18..58658e09c372 100644 --- a/arch/arm64/kvm/hyp/nvhe/psci-relay.c +++ b/arch/arm64/kvm/hyp/nvhe/psci-relay.c @@ -6,11 +6,12 @@ =20 #include #include +#include #include -#include #include #include =20 +#include #include #include =20 @@ -65,7 +66,7 @@ static unsigned long psci_call(unsigned long fn, unsigned= long arg0, { struct arm_smccc_res res; =20 - arm_smccc_1_1_smc(fn, arg0, arg1, arg2, &res); + hyp_smccc_1_1_smc(fn, arg0, arg1, arg2, &res); return res.a0; } =20 @@ -205,6 +206,7 @@ asmlinkage void __noreturn __kvm_host_psci_cpu_entry(bo= ol is_cpu_on) struct psci_boot_args *boot_args; struct kvm_cpu_context *host_ctxt; =20 + trace_hyp_enter(HYP_REASON_PSCI); host_ctxt =3D host_data_ptr(host_ctxt); =20 if (is_cpu_on) @@ -221,6 +223,7 @@ asmlinkage void __noreturn __kvm_host_psci_cpu_entry(bo= ol is_cpu_on) write_sysreg_el1(INIT_SCTLR_EL1_MMU_OFF, SYS_SCTLR); write_sysreg(INIT_PSTATE_EL1, SPSR_EL2); =20 + trace_hyp_exit(HYP_REASON_PSCI); __host_enter(host_ctxt); } =20 diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/swi= tch.c index d3b9ec8a7c28..3dc2bbab4bfc 100644 --- a/arch/arm64/kvm/hyp/nvhe/switch.c +++ b/arch/arm64/kvm/hyp/nvhe/switch.c @@ -7,7 +7,6 @@ #include #include =20 -#include #include #include #include @@ -21,6 +20,7 @@ #include #include #include +#include #include #include #include @@ -308,10 +308,13 @@ int __kvm_vcpu_run(struct kvm_vcpu *vcpu) __debug_switch_to_guest(vcpu); =20 do { + trace_hyp_exit(HYP_REASON_ERET_GUEST); + /* Jump in the fire! */ exit_code =3D __guest_enter(vcpu); =20 /* And we're baaack! */ + trace_hyp_enter(HYP_REASON_GUEST_EXIT); 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Tue, 02 Dec 2025 01:36:59 -0800 (PST) Date: Tue, 2 Dec 2025 09:36:22 +0000 In-Reply-To: <20251202093623.2337860-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251202093623.2337860-1-vdonnefort@google.com> X-Mailer: git-send-email 2.52.0.107.ga0afd4fd5b-goog Message-ID: <20251202093623.2337860-30-vdonnefort@google.com> Subject: [PATCH v9 29/30] KVM: arm64: Add selftest event support to nVHE/pKVM hyp From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-trace-kernel@vger.kernel.org, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, jstultz@google.com, qperret@google.com, will@kernel.org, aneesh.kumar@kernel.org, kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Add a selftest event that can be triggered from a `write_event` tracefs file. This intends to be used by trace remote selftests. Signed-off-by: Vincent Donnefort diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_= asm.h index 37c015b54ff6..e2de7ad64938 100644 --- a/arch/arm64/include/asm/kvm_asm.h +++ b/arch/arm64/include/asm/kvm_asm.h @@ -96,6 +96,7 @@ enum __kvm_host_smccc_func { __KVM_HOST_SMCCC_FUNC___tracing_update_clock, __KVM_HOST_SMCCC_FUNC___tracing_reset, __KVM_HOST_SMCCC_FUNC___tracing_enable_event, + __KVM_HOST_SMCCC_FUNC___tracing_write_event, }; =20 #define DECLARE_KVM_VHE_SYM(sym) extern char sym[] diff --git a/arch/arm64/include/asm/kvm_hypevents.h b/arch/arm64/include/as= m/kvm_hypevents.h index 268b3cd7a1b2..c276fd28e0bf 100644 --- a/arch/arm64/include/asm/kvm_hypevents.h +++ b/arch/arm64/include/asm/kvm_hypevents.h @@ -42,4 +42,15 @@ HYP_EVENT(hyp_exit, ), HE_PRINTK("reason=3D%s", __hyp_enter_exit_reason_str(__entry->reason)) ); + +HYP_EVENT(selftest, + HE_PROTO(u64 id), + HE_STRUCT( + he_field(u64, id) + ), + HE_ASSIGN( + __entry->id =3D id; + ), + RE_PRINTK("id=3D%llu", __entry->id) +); #endif diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/h= yp-main.c index ffda4850022f..13a6c5c4fabd 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -641,6 +641,15 @@ static void handle___tracing_enable_event(struct kvm_c= pu_context *host_ctxt) cpu_reg(host_ctxt, 1) =3D __tracing_enable_event(id, enable); } =20 +static void handle___tracing_write_event(struct kvm_cpu_context *host_ctxt) +{ + DECLARE_REG(u64, id, host_ctxt, 1); + + trace_selftest(id); + + cpu_reg(host_ctxt, 1) =3D 0; +} + typedef void (*hcall_t)(struct kvm_cpu_context *); =20 #define HANDLE_FUNC(x) [__KVM_HOST_SMCCC_FUNC_##x] =3D (hcall_t)handle_##x @@ -689,6 +698,7 @@ static const hcall_t host_hcall[] =3D { HANDLE_FUNC(__tracing_update_clock), HANDLE_FUNC(__tracing_reset), HANDLE_FUNC(__tracing_enable_event), + HANDLE_FUNC(__tracing_write_event), }; =20 static void handle_host_hcall(struct kvm_cpu_context *host_ctxt) diff --git a/arch/arm64/kvm/hyp_trace.c b/arch/arm64/kvm/hyp_trace.c index 1ad6a55ba95c..7b537222f364 100644 --- a/arch/arm64/kvm/hyp_trace.c +++ b/arch/arm64/kvm/hyp_trace.c @@ -348,8 +348,32 @@ static int hyp_trace_clock_show(struct seq_file *m, vo= id *v) } DEFINE_SHOW_ATTRIBUTE(hyp_trace_clock); 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Tue, 02 Dec 2025 01:37:00 -0800 (PST) Date: Tue, 2 Dec 2025 09:36:23 +0000 In-Reply-To: <20251202093623.2337860-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20251202093623.2337860-1-vdonnefort@google.com> X-Mailer: git-send-email 2.52.0.107.ga0afd4fd5b-goog Message-ID: <20251202093623.2337860-31-vdonnefort@google.com> Subject: [PATCH v9 30/30] tracing: selftests: Add hypervisor trace remote tests From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-trace-kernel@vger.kernel.org, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, jstultz@google.com, qperret@google.com, will@kernel.org, aneesh.kumar@kernel.org, kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort , Shuah Khan , linux-kselftest@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Run the trace remote selftests with the trace remote 'hypervisor', This trace remote is most likely created when the arm64 KVM nVHE/pKVM hypervisor is in use. Cc: Shuah Khan Cc: linux-kselftest@vger.kernel.org Signed-off-by: Vincent Donnefort diff --git a/tools/testing/selftests/ftrace/test.d/remotes/hypervisor/buffe= r_size.tc b/tools/testing/selftests/ftrace/test.d/remotes/hypervisor/buffer= _size.tc new file mode 100644 index 000000000000..64bf859d6406 --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/remotes/hypervisor/buffer_size.= tc @@ -0,0 +1,11 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# description: Test hypervisor trace buffer size +# requires: remotes/hypervisor/write_event + +SOURCE_REMOTE_TEST=3D1 +. $TEST_DIR/remotes/buffer_size.tc + +set -e +setup_remote "hypervisor" +test_buffer_size diff --git a/tools/testing/selftests/ftrace/test.d/remotes/hypervisor/reset= .tc b/tools/testing/selftests/ftrace/test.d/remotes/hypervisor/reset.tc new file mode 100644 index 000000000000..7fe3b09b34e3 --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/remotes/hypervisor/reset.tc @@ -0,0 +1,11 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# description: Test hypervisor trace buffer reset +# requires: remotes/hypervisor/write_event + +SOURCE_REMOTE_TEST=3D1 +. $TEST_DIR/remotes/reset.tc + +set -e +setup_remote "hypervisor" +test_reset diff --git a/tools/testing/selftests/ftrace/test.d/remotes/hypervisor/trace= .tc b/tools/testing/selftests/ftrace/test.d/remotes/hypervisor/trace.tc new file mode 100644 index 000000000000..b937c19ca7f9 --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/remotes/hypervisor/trace.tc @@ -0,0 +1,11 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# description: Test hypervisor non-consuming trace read +# requires: remotes/hypervisor/write_event + +SOURCE_REMOTE_TEST=3D1 +. $TEST_DIR/remotes/trace.tc + +set -e +setup_remote "hypervisor" +test_trace diff --git a/tools/testing/selftests/ftrace/test.d/remotes/hypervisor/trace= _pipe.tc b/tools/testing/selftests/ftrace/test.d/remotes/hypervisor/trace_p= ipe.tc new file mode 100644 index 000000000000..66aa1b76c147 --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/remotes/hypervisor/trace_pipe.tc @@ -0,0 +1,11 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# description: Test hypervisor consuming trace read +# requires: remotes/hypervisor/write_event + +SOURCE_REMOTE_TEST=3D1 +. $TEST_DIR/remotes/trace_pipe.tc + +set -e +setup_remote "hypervisor" +test_trace_pipe diff --git a/tools/testing/selftests/ftrace/test.d/remotes/hypervisor/unloa= ding.tc b/tools/testing/selftests/ftrace/test.d/remotes/hypervisor/unloadin= g.tc new file mode 100644 index 000000000000..1dafde3414ab --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/remotes/hypervisor/unloading.tc @@ -0,0 +1,11 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# description: Test hypervisor trace buffer unloading +# requires: remotes/hypervisor/write_event + +SOURCE_REMOTE_TEST=3D1 +. $TEST_DIR/remotes/unloading.tc + +set -e +setup_remote "hypervisor" +test_unloading --=20 2.52.0.107.ga0afd4fd5b-goog