From patchwork Thu Mar 20 11:41:44 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiri Olsa X-Patchwork-Id: 14023781 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 D860921C9EB; Thu, 20 Mar 2025 11:43:47 +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=1742471027; cv=none; b=fNsIN9a4RjeyyEymxOSgFq4gnY2f35NYQ0PyNBBQoPmI/RM788EWDV5sCsToYxsoDSMsVR5utFgyg61HD+rLEugVbZ36iwDuYRNNdZm3I54a3whlkrDp2DO8h+1TmVM3GSFtweP86PepavLUuButLZpQnEYusfaeLJNGAEmfPdY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742471027; c=relaxed/simple; bh=x27U7Ss5PyOwovmggHbntsdXgvgqCagPQvPv8hvGwrk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=YPh8roASaExYvkToFN/rpgSvcFQMSkDzQPgjgWPNnRG3WMP86v3hAZrHfdhLpM89/Xz72oD542VNuxNjO5p9lGx8xG8ty7HkdhF5HrxPM+SLQBHVK64jeTxk5cLMWKPhp2gX/8mIo07KrXC1md0/cTVMFxWxmbwS+rGurRJ6wzA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UqFPFHUM; 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="UqFPFHUM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D6B6FC4CEDD; Thu, 20 Mar 2025 11:43:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1742471027; bh=x27U7Ss5PyOwovmggHbntsdXgvgqCagPQvPv8hvGwrk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UqFPFHUMoG2Md9tUpzqv0JAJNK7XJpWbZq1ZhnW2LTlSGcigkR1kCyO8jv1/hNWXG rhGxLWy7eHJmQ/c1vQDF3re2KbwNO2/AYFR8RkLvLNbAimb9ZV5TzMXkAgATWGtpFr 1GvMcDvl59/ODcrcQ9E6jeBFnbF2rzdGCjyfRcYwvJmKya4BNHv2nmajtO0oSVClWo ZIHGtszSGU5VbexmKQ/dknEfqT614YIkprHe6x6mb35hSxHnccq8fPCmQxL3Ed0Xis nCwxCOCpjheG2MQLazDQAm4/P6/7XYP5IyUp6x11JCd2AX88elfWcbfTaLrcoJL+iF GrdcY2tSbNNAg== From: Jiri Olsa To: Oleg Nesterov , Peter Zijlstra , Andrii Nakryiko Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, x86@kernel.org, Song Liu , Yonghong Song , John Fastabend , Hao Luo , Steven Rostedt , Masami Hiramatsu , Alan Maguire , David Laight , =?utf-8?q?Thomas_Wei=C3=9Fschuh?= Subject: [PATCH RFCv3 09/23] uprobes/x86: Add mapping for optimized uprobe trampolines Date: Thu, 20 Mar 2025 12:41:44 +0100 Message-ID: <20250320114200.14377-10-jolsa@kernel.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250320114200.14377-1-jolsa@kernel.org> References: <20250320114200.14377-1-jolsa@kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-State: RFC Adding support to add special mapping for for user space trampoline with following functions: uprobe_trampoline_get - find or add related uprobe_trampoline uprobe_trampoline_put - remove ref or destroy uprobe_trampoline The user space trampoline is exported as architecture specific user space special mapping, which is provided by arch_uprobe_trampoline_mapping function. The uprobe trampoline needs to be callable/reachable from the probe address, so while searching for available address we use uprobe_is_callable function to decide if the uprobe trampoline is callable from the probe address. All uprobe_trampoline objects are stored in uprobes_state object and are cleaned up when the process mm_struct goes down. Adding new arch hooks for that, because this change is x86_64 specific. Locking is provided by callers in following changes. Signed-off-by: Jiri Olsa --- arch/x86/kernel/uprobes.c | 123 ++++++++++++++++++++++++++++++++++++++ include/linux/uprobes.h | 6 ++ kernel/events/uprobes.c | 10 ++++ kernel/fork.c | 1 + 4 files changed, 140 insertions(+) diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c index b11dcd47edaa..5ee2cce4c63e 100644 --- a/arch/x86/kernel/uprobes.c +++ b/arch/x86/kernel/uprobes.c @@ -742,6 +742,129 @@ static void riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) *sr = utask->autask.saved_scratch_register; } } + +struct uprobe_trampoline { + struct hlist_node node; + unsigned long vaddr; + atomic64_t ref; +}; + +static bool is_reachable_by_call(unsigned long vtramp, unsigned long vaddr) +{ + long delta = (long)(vaddr + 5 - vtramp); + + return delta >= INT_MIN && delta <= INT_MAX; +} + +static unsigned long find_nearest_page(unsigned long vaddr) +{ + struct vm_area_struct *vma, *prev = NULL; + unsigned long prev_vm_end = PAGE_SIZE; + VMA_ITERATOR(vmi, current->mm, 0); + + vma = vma_next(&vmi); + while (vma) { + if (prev) + prev_vm_end = prev->vm_end; + if (vma->vm_start - prev_vm_end >= PAGE_SIZE) { + if (is_reachable_by_call(prev_vm_end, vaddr)) + return prev_vm_end; + if (is_reachable_by_call(vma->vm_start - PAGE_SIZE, vaddr)) + return vma->vm_start - PAGE_SIZE; + } + prev = vma; + vma = vma_next(&vmi); + } + + return 0; +} + +static struct uprobe_trampoline *create_uprobe_trampoline(unsigned long vaddr) +{ + struct pt_regs *regs = task_pt_regs(current); + const struct vm_special_mapping *mapping; + struct mm_struct *mm = current->mm; + struct vm_area_struct *vma; + struct uprobe_trampoline *tramp; + + mapping = user_64bit_mode(regs) ? &tramp_mapping : NULL; + if (!mapping) + return NULL; + + vaddr = find_nearest_page(vaddr); + if (!vaddr) + return NULL; + + tramp = kzalloc(sizeof(*tramp), GFP_KERNEL); + if (unlikely(!tramp)) + return NULL; + + atomic64_set(&tramp->ref, 1); + tramp->vaddr = vaddr; + + vma = _install_special_mapping(mm, tramp->vaddr, PAGE_SIZE, + VM_READ|VM_EXEC|VM_MAYEXEC|VM_MAYREAD|VM_DONTCOPY|VM_IO, + mapping); + if (IS_ERR(vma)) + goto free_area; + return tramp; + + free_area: + kfree(tramp); + return NULL; +} + +__maybe_unused +static struct uprobe_trampoline *uprobe_trampoline_get(unsigned long vaddr) +{ + struct uprobes_state *state = ¤t->mm->uprobes_state; + struct uprobe_trampoline *tramp = NULL; + + hlist_for_each_entry(tramp, &state->head_tramps, node) { + if (is_reachable_by_call(tramp->vaddr, vaddr)) { + atomic64_inc(&tramp->ref); + return tramp; + } + } + + tramp = create_uprobe_trampoline(vaddr); + if (!tramp) + return NULL; + + hlist_add_head(&tramp->node, &state->head_tramps); + return tramp; +} + +static void destroy_uprobe_trampoline(struct uprobe_trampoline *tramp) +{ + hlist_del(&tramp->node); + kfree(tramp); +} + +__maybe_unused +static void uprobe_trampoline_put(struct uprobe_trampoline *tramp) +{ + if (tramp == NULL) + return; + + if (atomic64_dec_and_test(&tramp->ref)) + destroy_uprobe_trampoline(tramp); +} + +void arch_uprobe_init_state(struct mm_struct *mm) +{ + INIT_HLIST_HEAD(&mm->uprobes_state.head_tramps); +} + +void arch_uprobe_clear_state(struct mm_struct *mm) +{ + struct uprobes_state *state = &mm->uprobes_state; + struct uprobe_trampoline *tramp; + struct hlist_node *n; + + hlist_for_each_entry_safe(tramp, n, &state->head_tramps, node) + destroy_uprobe_trampoline(tramp); +} #else /* 32-bit: */ /* * No RIP-relative addressing on 32-bit diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h index 4a2b950beefd..7bde68871150 100644 --- a/include/linux/uprobes.h +++ b/include/linux/uprobes.h @@ -17,6 +17,7 @@ #include #include #include +#include struct uprobe; struct vm_area_struct; @@ -185,6 +186,9 @@ struct xol_area; struct uprobes_state { struct xol_area *xol_area; +#ifdef CONFIG_X86_64 + struct hlist_head head_tramps; +#endif }; typedef int (*uprobe_write_verify_t)(struct page *page, unsigned long vaddr, uprobe_opcode_t *opcode, int nbytes); @@ -233,6 +237,8 @@ extern void *arch_uretprobe_trampoline(unsigned long *psize); extern unsigned long uprobe_get_trampoline_vaddr(void); extern void uprobe_copy_from_page(struct page *page, unsigned long vaddr, void *dst, int len); extern void handle_syscall_uprobe(struct pt_regs *regs, unsigned long bp_vaddr); +extern void arch_uprobe_clear_state(struct mm_struct *mm); +extern void arch_uprobe_init_state(struct mm_struct *mm); #else /* !CONFIG_UPROBES */ struct uprobes_state { }; diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 4de04075576c..9370df47ec71 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -1793,6 +1793,14 @@ static struct xol_area *get_xol_area(void) return area; } +void __weak arch_uprobe_clear_state(struct mm_struct *mm) +{ +} + +void __weak arch_uprobe_init_state(struct mm_struct *mm) +{ +} + /* * uprobe_clear_state - Free the area allocated for slots. */ @@ -1804,6 +1812,8 @@ void uprobe_clear_state(struct mm_struct *mm) delayed_uprobe_remove(NULL, mm); mutex_unlock(&delayed_uprobe_lock); + arch_uprobe_clear_state(mm); + if (!area) return; diff --git a/kernel/fork.c b/kernel/fork.c index e27fe5d5a15c..36a0f073b913 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1260,6 +1260,7 @@ static void mm_init_uprobes_state(struct mm_struct *mm) { #ifdef CONFIG_UPROBES mm->uprobes_state.xol_area = NULL; + arch_uprobe_init_state(mm); #endif }