From nobody Fri Dec 19 18:43:30 2025 Received: from out-173.mta0.migadu.com (out-173.mta0.migadu.com [91.218.175.173]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3E9E82C15BA for ; Mon, 13 Oct 2025 17:48:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.173 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760377700; cv=none; b=tPTHchsuDy1DEqFX1CxYH0ms0WTH9knxSxIed4/NVlNHLxtHXX22iuqKImDBJZQztI8RqS3H/hGsIcgbUp+8hsPx+c2MJycKhHboI1jem4bbjcJw+klvd+WiQBWfu1ed6Ypvr7nDrlnBPCny/tAvylfXlRLWzmeKjbIkDgfLx3s= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760377700; c=relaxed/simple; bh=U0voQM2oYnf6STeO6/rk9aLxKnrO1RiaTGJ/8zUau1w=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=S7G4cxLDl+I96aEHqzzN5RjLmwUt9xaQhRtYBXXf6JycGnRHhQrdVzdv3e0A1V0ipBFG9yi971g7Pyi1T6RenjP0OE7aS4wd5SeVQ9LZcDtoM0UnaOiGU3waKKUGx+ZOgGbGv1+kd6RiP6w9WJm+0db1bjlDo7A8Sl/Sa391lAw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=dqog44Hl; arc=none smtp.client-ip=91.218.175.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="dqog44Hl" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1760377696; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=GFSgpLJ9oy5bTPXjycAjjR+uiZnaDlBjDtnbne3KHWA=; b=dqog44HlD/xi4SmzgPayoGAyNglOXEbXHUVvDjSrKnNlF3zG9OY+/PnBjRu+tI5R08bv9L 9qo8QWSiIBxn8QVr5br7rI2wp/EfK/WDxBe87TvPgk/V9vehAAux3m0Izgp2PxAQJgot8B Aw2WZP8/zaM7h7tp6DhqHswK/xTC768= From: Tao Chen To: peterz@infradead.org, mingo@redhat.com, acme@kernel.org, namhyung@kernel.org, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, irogers@google.com, adrian.hunter@intel.com, kan.liang@linux.intel.com, song@kernel.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com Cc: linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, Tao Chen Subject: [PATCH bpf-next RFC 1/2] perf: Use extern perf_callchain_entry for get_perf_callchain Date: Tue, 14 Oct 2025 01:47:20 +0800 Message-ID: <20251013174721.2681091-2-chen.dylane@linux.dev> In-Reply-To: <20251013174721.2681091-1-chen.dylane@linux.dev> References: <20251013174721.2681091-1-chen.dylane@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" From bpf stack map, we want to use our own buffers to avoid unnecessary cop= y, so let us pass it directly. Signed-off-by: Tao Chen --- include/linux/perf_event.h | 5 +++-- kernel/bpf/stackmap.c | 4 ++-- kernel/events/callchain.c | 18 ++++++++++++------ kernel/events/core.c | 2 +- 4 files changed, 18 insertions(+), 11 deletions(-) diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index ec9d9602568..ca69ad2723c 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1719,8 +1719,9 @@ DECLARE_PER_CPU(struct perf_callchain_entry, perf_cal= lchain_entry); extern void perf_callchain_user(struct perf_callchain_entry_ctx *entry, st= ruct pt_regs *regs); extern void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, = struct pt_regs *regs); extern struct perf_callchain_entry * -get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool us= er, - u32 max_stack, bool crosstask, bool add_mark); +get_perf_callchain(struct pt_regs *regs, struct perf_callchain_entry *exte= rnal_entry, + u32 init_nr, bool kernel, bool user, u32 max_stack, bool crosstask, + bool add_mark); extern int get_callchain_buffers(int max_stack); extern void put_callchain_buffers(void); extern struct perf_callchain_entry *get_callchain_entry(int *rctx); diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index 2e182a3ac4c..e6e40f22826 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -314,7 +314,7 @@ BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, str= uct bpf_map *, map, if (max_depth > sysctl_perf_event_max_stack) max_depth =3D sysctl_perf_event_max_stack; =20 - trace =3D get_perf_callchain(regs, 0, kernel, user, max_depth, + trace =3D get_perf_callchain(regs, NULL, 0, kernel, user, max_depth, false, false); =20 if (unlikely(!trace)) @@ -451,7 +451,7 @@ static long __bpf_get_stack(struct pt_regs *regs, struc= t task_struct *task, else if (kernel && task) trace =3D get_callchain_entry_for_task(task, max_depth); else - trace =3D get_perf_callchain(regs, 0, kernel, user, max_depth, + trace =3D get_perf_callchain(regs, NULL, 0, kernel, user, max_depth, crosstask, false); =20 if (unlikely(!trace) || trace->nr < skip) { diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c index 6c83ad674d0..fe5d2d58deb 100644 --- a/kernel/events/callchain.c +++ b/kernel/events/callchain.c @@ -217,16 +217,21 @@ static void fixup_uretprobe_trampoline_entries(struct= perf_callchain_entry *entr } =20 struct perf_callchain_entry * -get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool us= er, - u32 max_stack, bool crosstask, bool add_mark) +get_perf_callchain(struct pt_regs *regs, struct perf_callchain_entry *exte= rnal_entry, + u32 init_nr, bool kernel, bool user, u32 max_stack, bool crosstask, + bool add_mark) { struct perf_callchain_entry *entry; struct perf_callchain_entry_ctx ctx; int rctx, start_entry_idx; =20 - entry =3D get_callchain_entry(&rctx); - if (!entry) - return NULL; + if (external_entry) { + entry =3D external_entry; + } else { + entry =3D get_callchain_entry(&rctx); + if (!entry) + return NULL; + } =20 ctx.entry =3D entry; ctx.max_stack =3D max_stack; @@ -262,7 +267,8 @@ get_perf_callchain(struct pt_regs *regs, u32 init_nr, b= ool kernel, bool user, } =20 exit_put: - put_callchain_entry(rctx); + if (!external_entry) + put_callchain_entry(rctx); =20 return entry; } diff --git a/kernel/events/core.c b/kernel/events/core.c index 1d354778dcd..08ce44db18f 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -8204,7 +8204,7 @@ perf_callchain(struct perf_event *event, struct pt_re= gs *regs) if (!kernel && !user) return &__empty_callchain; =20 - callchain =3D get_perf_callchain(regs, 0, kernel, user, + callchain =3D get_perf_callchain(regs, NULL, 0, kernel, user, max_stack, crosstask, true); return callchain ?: &__empty_callchain; } --=20 2.48.1