From nobody Sun Nov 24 14:22:40 2024 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 021181D362B; Tue, 5 Nov 2024 13:35:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730813705; cv=none; b=WaEFz+aGzBNWSIByfQllXMs878oVJIgZbTZjtBUMyTCr5txkRoqaIOt4d254RT37tnRMmcs4ax+rnKhr45RT5J0dT4NhYTsGbRjUJGkJza3BSj+6tufyNkl9TPusCSJf0tyx+e1bSxy3di9Gn46uk/RaRihuoDDH0NTtV5aMWYA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730813705; c=relaxed/simple; bh=I1y0BuXthi+rHhswQatOYfSek/3hTV8+LS5gYMFqRu4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=D+VRg9/5nxkCOgG3XSRjcLsaInXxYTBgg9Gm7QEHL1wdecWwwvTop/XVrO4n3o12SgSww0zpEBQ2748GlrEyiBm8AF7u4nDtsG2T3XNkDrGpQ2IytukRRd28ekME3uRfiOhLPFSn88sue5MuKrugu2zXS3wnej/EVQp3JPi8Pyk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=aOvBOjHc; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="aOvBOjHc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4F706C4CECF; Tue, 5 Nov 2024 13:35:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730813704; bh=I1y0BuXthi+rHhswQatOYfSek/3hTV8+LS5gYMFqRu4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=aOvBOjHcCiPYpk3cjZcc+/WX5HImRKZP8408IMUNNBIGIIKRn/gGL6BKhOoOKjPTF gGCfz6ghBC2sL1WKeV0MaZk7WOWkOcoF8fFwQVTmG7ZHrfHJNTiagHb52okE5huVDd 4OlO866jbYtLIUAFncsc3IhNst4vSSI7auAMa5zh12otRr1dK2a81McnYocI3xg5ZJ EysQcRRblaXeMPk7eAQxVLep6/UcczxC01MY+v6hPhDFVhnDY+2im5fq2lh5Kgqsud 2JkfyjLfWt8BC621CKTyEmfqXFvTa5jB29rWSzlf3ekf4PNVb6gQiQiAzMG+U2X1sT SGcdFldm7FwsA== From: Jiri Olsa To: Oleg Nesterov , Peter Zijlstra , Andrii Nakryiko Cc: bpf@vger.kernel.org, Song Liu , Yonghong Song , John Fastabend , Hao Luo , Steven Rostedt , Masami Hiramatsu , Alan Maguire , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: [RFC perf/core 05/11] uprobes: Add mapping for optimized uprobe trampolines Date: Tue, 5 Nov 2024 14:33:59 +0100 Message-ID: <20241105133405.2703607-6-jolsa@kernel.org> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241105133405.2703607-1-jolsa@kernel.org> References: <20241105133405.2703607-1-jolsa@kernel.org> 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 Content-Type: text/plain; charset="utf-8" Adding interface to add special mapping for user space page that will be used as place holder for uprobe trampoline in following changes. The get_tramp_area(vaddr) function either finds 'callable' page or create new one. The 'callable' means it's reachable by call instruction (from vaddr argument) and is decided by each arch via new arch_uprobe_is_callable function. The put_tramp_area function either drops refcount or destroys the special mapping and all the maps are clean up when the process goes down. Signed-off-by: Jiri Olsa --- include/linux/uprobes.h | 12 ++++ kernel/events/uprobes.c | 141 ++++++++++++++++++++++++++++++++++++++++ kernel/fork.c | 2 + 3 files changed, 155 insertions(+) diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h index be306028ed59..222d8e82cee2 100644 --- a/include/linux/uprobes.h +++ b/include/linux/uprobes.h @@ -172,6 +172,15 @@ struct xol_area; =20 struct uprobes_state { struct xol_area *xol_area; + struct hlist_head tramp_head; + struct mutex tramp_mutex; +}; + +struct tramp_area { + unsigned long vaddr; + struct page *page; + struct hlist_node node; + refcount_t ref; }; =20 extern void __init uprobes_init(void); @@ -219,6 +228,9 @@ extern int uprobe_verify_opcode(struct page *page, unsi= gned long vaddr, uprobe_o extern int arch_uprobe_verify_opcode(struct page *page, unsigned long vadd= r, uprobe_opcode_t *new_opcode, void *data); extern bool arch_uprobe_is_register(uprobe_opcode_t *insn, int len, void *= data); +struct tramp_area *get_tramp_area(unsigned long vaddr); +void put_tramp_area(struct tramp_area *area); +bool arch_uprobe_is_callable(unsigned long vtramp, unsigned long vaddr); #else /* !CONFIG_UPROBES */ struct uprobes_state { }; diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 944d9df1f081..a44305c559a4 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -616,6 +616,145 @@ set_orig_insn(struct arch_uprobe *auprobe, struct mm_= struct *mm, unsigned long v (uprobe_opcode_t *)&auprobe->insn, UPROBE_SWBP_INSN_SIZE, NULL); } =20 +bool __weak arch_uprobe_is_callable(unsigned long vtramp, unsigned long va= ddr) +{ + return false; +} + +static unsigned long find_nearest_page(unsigned long vaddr) +{ + struct mm_struct *mm =3D current->mm; + struct vm_area_struct *vma, *prev; + VMA_ITERATOR(vmi, mm, 0); + + prev =3D vma_next(&vmi); + vma =3D vma_next(&vmi); + while (vma) { + if (vma->vm_start - prev->vm_end >=3D PAGE_SIZE && + arch_uprobe_is_callable(prev->vm_end, vaddr)) + return prev->vm_end; + + prev =3D vma; + vma =3D vma_next(&vmi); + } + + return 0; +} + +static vm_fault_t tramp_fault(const struct vm_special_mapping *sm, + struct vm_area_struct *vma, struct vm_fault *vmf) +{ + struct hlist_head *head =3D &vma->vm_mm->uprobes_state.tramp_head; + struct tramp_area *area; + + hlist_for_each_entry(area, head, node) { + if (vma->vm_start =3D=3D area->vaddr) { + vmf->page =3D area->page; + get_page(vmf->page); + return 0; + } + } + + return -EINVAL; +} + +static int tramp_mremap(const struct vm_special_mapping *sm, struct vm_are= a_struct *new_vma) +{ + return -EPERM; +} + +static const struct vm_special_mapping tramp_mapping =3D { + .name =3D "[uprobes-trampoline]", + .fault =3D tramp_fault, + .mremap =3D tramp_mremap, +}; + +static struct tramp_area *create_tramp_area(unsigned long vaddr) +{ + struct mm_struct *mm =3D current->mm; + struct vm_area_struct *vma; + struct tramp_area *area; + + vaddr =3D find_nearest_page(vaddr); + if (!vaddr) + return NULL; + + area =3D kzalloc(sizeof(*area), GFP_KERNEL); + if (unlikely(!area)) + return NULL; + + area->page =3D alloc_page(GFP_HIGHUSER); + if (!area->page) + goto free_area; + + refcount_set(&area->ref, 1); + area->vaddr =3D vaddr; + + vma =3D _install_special_mapping(mm, area->vaddr, PAGE_SIZE, + VM_READ|VM_EXEC|VM_MAYEXEC|VM_MAYREAD|VM_DONTCOPY|VM_IO, + &tramp_mapping); + if (!IS_ERR(vma)) + return area; + + __free_page(area->page); + free_area: + kfree(area); + return NULL; +} + +struct tramp_area *get_tramp_area(unsigned long vaddr) +{ + struct uprobes_state *state =3D ¤t->mm->uprobes_state; + struct tramp_area *area =3D NULL; + + mutex_lock(&state->tramp_mutex); + hlist_for_each_entry(area, &state->tramp_head, node) { + if (arch_uprobe_is_callable(area->vaddr, vaddr)) { + refcount_inc(&area->ref); + goto unlock; + } + } + + area =3D create_tramp_area(vaddr); + if (area) + hlist_add_head(&area->node, &state->tramp_head); + +unlock: + mutex_unlock(&state->tramp_mutex); + return area; +} + +static void destroy_tramp_area(struct tramp_area *area) +{ + hlist_del(&area->node); + put_page(area->page); + kfree(area); +} + +void put_tramp_area(struct tramp_area *area) +{ + struct mm_struct *mm =3D current->mm; + struct uprobes_state *state =3D &mm->uprobes_state; + + if (area =3D=3D NULL) + return; + + mutex_lock(&state->tramp_mutex); + if (refcount_dec_and_test(&area->ref)) + destroy_tramp_area(area); + mutex_unlock(&state->tramp_mutex); +} + +static void clear_tramp_head(struct mm_struct *mm) +{ + struct uprobes_state *state =3D &mm->uprobes_state; + struct tramp_area *area; + struct hlist_node *n; + + hlist_for_each_entry_safe(area, n, &state->tramp_head, node) + destroy_tramp_area(area); +} + /* uprobe should have guaranteed positive refcount */ static struct uprobe *get_uprobe(struct uprobe *uprobe) { @@ -1788,6 +1927,8 @@ void uprobe_clear_state(struct mm_struct *mm) delayed_uprobe_remove(NULL, mm); mutex_unlock(&delayed_uprobe_lock); =20 + clear_tramp_head(mm); + if (!area) return; =20 diff --git a/kernel/fork.c b/kernel/fork.c index 89ceb4a68af2..b1fe431e5cce 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1248,6 +1248,8 @@ static void mm_init_uprobes_state(struct mm_struct *m= m) { #ifdef CONFIG_UPROBES mm->uprobes_state.xol_area =3D NULL; + mutex_init(&mm->uprobes_state.tramp_mutex); + INIT_HLIST_HEAD(&mm->uprobes_state.tramp_head); #endif } =20 --=20 2.47.0