From nobody Sat Sep 26 01:04:32 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 26649345EAC; Mon, 7 Sep 2026 03:46:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788752797; cv=none; b=JI2qVhptmtXtxz8qSpcnm4N64TaYeeYIT72pMIQ8jqHfi9z4CidNUs5ixW0VVZQLsMJn80jF2bpj2KhEyhPrUgfYv0ByWxMqp0FpBsuYiZsJIbE/qcsCtpbD+ouY3hjdV0ZWUCCGObHHxvoyrpycHvxmYdKQK86ym7SJg3mRhhU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788752797; c=relaxed/simple; bh=++emXcP9SPk1N6KlszECK+hTyKvu/kLTGVZdg7HV0Vo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=cgPB36CMOUcuIbDKBlLZOsybhPlWZIIxMn3X9f/BMpBW6lbcN2xzESTxCpTQYDhW6JcJULLBbhjnBV4W0i/cBFqdNnOLn1SHurSr5wEVLGZTvpXttOVjY+Jz+DH7qIIKTwPfIGsLcN7bWXI6rxrEQtRY+09052KwNMTgVGz5Hx4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GyH4N0UD; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="GyH4N0UD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 42D291F00A3A; Mon, 7 Sep 2026 03:46:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788752795; bh=ECQ2YrO3c6fTy3LNvcZ/qkWRkP34JaQc5nHEXsbIZYs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=GyH4N0UDZVDoofssCO9BCQETKgJkXbuM/BBGZ99C4OaDrACL5z4GlsesMge794BV5 82kDqbXwzJIYq65lRbzF0a5BzxdGpBre4Hf2YBNkxZqZt7r20i6hFB///vWIPLD6Ml +qZIf7N6MwhLKaQmRP0h6zF8ZOf8QhEmU1urfBhPEta7COD6DSFIABXd90RvHNLq8J krIV+RZX8O82czbkDWmUVlYaZqPV8hyFdf47xt7/VyZzHdrJp0QJz7lVH+XEMs6iew B0ykl5MnvLjlyZ82jzQlByY6qQwE0O2lV3Thl7J0IIKByDSCgDTdoRt33mSINzrR2B lw6Cx0YDTIHIg== From: "Masami Hiramatsu (Google)" To: Steven Rostedt , Peter Zijlstra , Ingo Molnar , x86@kernel.org Cc: Jinchao Wang , Mathieu Desnoyers , Masami Hiramatsu , Thomas Gleixner , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Alexander Shishkin , Ian Rogers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: [PATCH v15 01/12] x86/mce: Fix hardware debug register corruption on task migration Date: Mon, 7 Sep 2026 12:46:30 +0900 Message-ID: <178875279006.93794.3424002631388906633.stgit@devnote2> X-Mailer: git-send-email 2.43.0 In-Reply-To: <178875277830.93794.14247844688761142429.stgit@devnote2> References: <178875277830.93794.14247844688761142429.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Masami Hiramatsu (Google) In exc_machine_check_user(), local_db_save() and local_db_restore() are invoked in the outer entry stubs (DEFINE_IDTENTRY_MCE_USER, DEFINE_FREDENTRY_MCE, and DEFINE_IDTENTRY_RAW), surrounding exc_machine_check_user(). However, exc_machine_check_user() calls irqentry_exit_to_user_mode(), which handles pending thread work and may schedule() if TIF_NEED_RESCHED is set. If the task migrates to another CPU during schedule(), local_db_restore() runs on the new CPU with the dr7 state saved from the old CPU. This corrupts the new CPU's DR7 hardware debug register and leaves the old CPU's DR7 disabled. In short, local_db_save() and local_db_restore() pair must be run on the same CPU. To fix this, move local_db_save() and local_db_restore() inside exc_machine_check_user() and exc_machine_check_kernel(). In exc_machine_check_user(), DR7 is saved and restored strictly around do_machine_check() to avoid schedule() during migration. In exc_machine_check_kernel(), local_db_save() is called at the entry point to prevent early memory accesses from triggering nested #DB exceptions, and restored on all exits. Fixes: cd840e424f27 ("x86/entry, mce: Disallow #DB during #MC") Assisted-by: Antigravity:gemini-3.8-flash Signed-off-by: Masami Hiramatsu (Google) --- Changes in v15: - Move local_db_save() to the entry of exc_machine_check_kernel() and restore it on early return from mce_check_crashing_cpu() to prevent nested #DB on watched variables. Changes in v14: - Newly added. --- arch/x86/kernel/cpu/mce/core.c | 27 ++++++++++----------------- 1 file changed, 10 insertions(+), 17 deletions(-) diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c index ab469605fc89..39f238952e14 100644 --- a/arch/x86/kernel/cpu/mce/core.c +++ b/arch/x86/kernel/cpu/mce/core.c @@ -2108,6 +2108,9 @@ bool filter_mce(struct mce *m) static __always_inline void exc_machine_check_kernel(struct pt_regs *regs) { irqentry_state_t irq_state; + unsigned long dr7; + + dr7 =3D local_db_save(); =20 WARN_ON_ONCE(user_mode(regs)); =20 @@ -2116,20 +2119,26 @@ static __always_inline void exc_machine_check_kerne= l(struct pt_regs *regs) * mce_check_crashing_cpu() for details. */ if (mca_cfg.initialized && mce_check_crashing_cpu()) - return; + goto out; =20 irq_state =3D irqentry_nmi_enter(regs); =20 do_machine_check(regs); =20 irqentry_nmi_exit(regs, irq_state); +out: + local_db_restore(dr7); } =20 static __always_inline void exc_machine_check_user(struct pt_regs *regs) { + unsigned long dr7; + irqentry_enter_from_user_mode(regs); =20 + dr7 =3D local_db_save(); do_machine_check(regs); + local_db_restore(dr7); =20 irqentry_exit_to_user_mode(regs); } @@ -2138,21 +2147,13 @@ static __always_inline void exc_machine_check_user(= struct pt_regs *regs) /* MCE hit kernel mode */ DEFINE_IDTENTRY_MCE(exc_machine_check) { - unsigned long dr7; - - dr7 =3D local_db_save(); exc_machine_check_kernel(regs); - local_db_restore(dr7); } =20 /* The user mode variant. */ DEFINE_IDTENTRY_MCE_USER(exc_machine_check) { - unsigned long dr7; - - dr7 =3D local_db_save(); exc_machine_check_user(regs); - local_db_restore(dr7); } =20 #ifdef CONFIG_X86_FRED @@ -2169,28 +2170,20 @@ DEFINE_IDTENTRY_MCE_USER(exc_machine_check) */ DEFINE_FREDENTRY_MCE(exc_machine_check) { - unsigned long dr7; - - dr7 =3D local_db_save(); if (user_mode(regs)) exc_machine_check_user(regs); else exc_machine_check_kernel(regs); - local_db_restore(dr7); } #endif #else /* 32bit unified entry point */ DEFINE_IDTENTRY_RAW(exc_machine_check) { - unsigned long dr7; - - dr7 =3D local_db_save(); if (user_mode(regs)) exc_machine_check_user(regs); else exc_machine_check_kernel(regs); - local_db_restore(dr7); } #endif From nobody Sat Sep 26 01:04:32 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 670F53EF67D; Mon, 7 Sep 2026 03:46:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788752809; cv=none; b=VnvZ8xr3T9HHxyZnNha/IL80H8k8cep9JVH06pLBA8B/0oheu5ktZ8vOOxgSJ8+JSzE+tkWqFTB+DUqZAHE9o+5gfCdWRN1jSbLHzyGF4IPUvgAk1hmTgzWxnzFKquxAxNygw2342hGnYq7pzKLQs0yQvjxkaboq5rWPUPxzARg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788752809; c=relaxed/simple; bh=5jwee3mxa2Gc9OlwQ8R82ruPedVY5V6k58lkYSyEREc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Pw5H9G7KKC7moKh6QFCUW/mlejY5zuHphp/MGjdbNc29r+VJCcCPkici0ZO9bDWQ6sBIe5mzpzi9H6jMH0BF5IhA6HSJQudj3SlGDiCWC3ucIj+XRmY8WlUv7mgMJN6+dxfQZmr/cRGx66ireNh030/01xrDG3mQinIrSsAC9U0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=OucTLQV0; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="OucTLQV0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 510EF1F00A3A; Mon, 7 Sep 2026 03:46:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788752807; bh=AfsQzl3BDQQf2gxeXS3jiDtJ8Hj30BTCWvv1cSe5GQc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=OucTLQV0yjGBulUzOFZtwXyMkHe93edhS9Z4L4XdaZAbtj4/hzNa8Xphw+/6pycbn EJ22xFwftLFVg6OE8rthbYc/fIX+agZczkQzIWy62b5Cp8Cz80vcTSJYoRpnD1MRn4 5JyiHMXMOfHElmK6C6oCg9koAt28beOnYLA3nR9zDGPG4S1Kgh6uwSkYv9U7Oj7V/9 nSN1FuwPLYJUzErTCdxXOGpP/FSd3iAGnZhvnDhVwFJm90mvq0ULigvFkh2Oi9tqaM jFsTe/G6OTlCFO/hqnIw4+D7Lvxe+KrhJ5tKI5Y2eT6dKh8KpmriiwG+7346ddqgS5 som0YgSWjsfFA== From: "Masami Hiramatsu (Google)" To: Steven Rostedt , Peter Zijlstra , Ingo Molnar , x86@kernel.org Cc: Jinchao Wang , Mathieu Desnoyers , Masami Hiramatsu , Thomas Gleixner , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Alexander Shishkin , Ian Rogers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: [PATCH v15 02/12] x86/hw_breakpoints: Make DR7 updates NMI safe Date: Mon, 7 Sep 2026 12:46:41 +0900 Message-ID: <178875280112.93794.5857698342827027053.stgit@devnote2> X-Mailer: git-send-email 2.43.0 In-Reply-To: <178875277830.93794.14247844688761142429.stgit@devnote2> References: <178875277830.93794.14247844688761142429.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Jinchao Wang Hardware breakpoint installation and removal run with IRQs disabled, but an NMI can still enter the same code through KGDB. The interrupted operation and the NMI can consequently claim the same slot or overwrite each other's DR7 state. Claim and release per-CPU slots with cmpxchg. Update cpu_dr7 with single-instruction per-CPU operations, and preserve hardware-first disable and hardware-last enable ordering. Add a per-CPU sequence number so interrupted DR7 writers and restore paths detect an NMI update and retry from the latest shadow state. Link: https://lore.kernel.org/all/4ee0a2efc9e8387af83286b8495b7d490247e165.= 1785067572.git.wangjinchao600@gmail.com/ Assisted-by: Antigravity:gemini-3.8-flash Signed-off-by: Jinchao Wang Signed-off-by: Masami Hiramatsu (Google) --- Changes in v15: - Always preserve DR7_FIXED_1 in arch_install_hw_breakpoint(), arch_uninstall_hw_breakpoint(), and hw_breakpoint_restore() to comply with the x86 architectural specification. - Wrap local_db_save() in a cpu_dr7_seq loop to detect NMI breakpoint updates and ensure DR7 is disabled before entry. - In local_db_restore(), if dr7 is 0 and an NMI modified breakpoints, restore DR7_FIXED_1 to undo the NMI's overwrite and preserve KVM guest isolation. - Always write "val | DR7_FIXED_1" to hardware DR7 in local_db_restore() to ensure architectural compliance. - Avoid modifying the saved dr7 argument in-place across retry loops. Changes in v14: - In local_db_restore(), return immediately if saved dr7 is 0 to avoid overwriting intentionally cleared hardware DR7 state (e.g. KVM guest entry) with cpu_dr7 when an NMI increments cpu_dr7_seq. Changes in v13: - Add compiler barriers (barrier()) before checking cpu_dr7_seq to prevent the compiler from hoisting the sequence check before debug register updates or shadow state modifications. Changes in v12: - Use stack variables dr7 and dr7_seq directly in exc_nmi() and remove unnecessary per-CPU nmi_dr7 and nmi_dr7_seq variables. --- arch/x86/include/asm/debugreg.h | 67 ++++++++++++++++++-------- arch/x86/kernel/cpu/mce/core.c | 10 ++-- arch/x86/kernel/hw_breakpoint.c | 101 ++++++++++++++++++++---------------= ---- arch/x86/kernel/nmi.c | 7 ++- arch/x86/kernel/traps.c | 10 +++- 5 files changed, 115 insertions(+), 80 deletions(-) diff --git a/arch/x86/include/asm/debugreg.h b/arch/x86/include/asm/debugre= g.h index 854d82b88ff4..3399e166d304 100644 --- a/arch/x86/include/asm/debugreg.h +++ b/arch/x86/include/asm/debugreg.h @@ -18,6 +18,7 @@ #define DR7_FIXED_1 0x00000400 =20 DECLARE_PER_CPU(unsigned long, cpu_dr7); +DECLARE_PER_CPU(unsigned int, cpu_dr7_seq); =20 #ifndef CONFIG_PARAVIRT_XXL /* @@ -125,40 +126,66 @@ static __always_inline bool hw_breakpoint_active(void) =20 extern void hw_breakpoint_restore(void); =20 -static __always_inline unsigned long local_db_save(void) +static __always_inline void local_db_save(unsigned long *dr7, + unsigned int *dr7_seq) { - unsigned long dr7; + do { + *dr7_seq =3D this_cpu_read(cpu_dr7_seq); + *dr7 =3D 0; =20 - if (cpu_feature_enabled(X86_FEATURE_HYPERVISOR) && !hw_breakpoint_active(= )) - return 0; - - get_debugreg(dr7, 7); + if (cpu_feature_enabled(X86_FEATURE_HYPERVISOR) && + !hw_breakpoint_active()) + return; =20 - /* Architecturally set bit */ - dr7 &=3D ~DR7_FIXED_1; - if (dr7) - set_debugreg(DR7_FIXED_1, 7); + get_debugreg(*dr7, 7); =20 - /* - * Ensure the compiler doesn't lower the above statements into - * the critical section; disabling breakpoints late would not - * be good. - */ - barrier(); + /* Architecturally set bit */ + *dr7 &=3D ~DR7_FIXED_1; + if (*dr7) + set_debugreg(DR7_FIXED_1, 7); =20 - return dr7; + /* + * Ensure the compiler doesn't lower the above statements into + * the critical section; disabling breakpoints late would not + * be good. + */ + barrier(); + } while (unlikely(*dr7_seq !=3D this_cpu_read(cpu_dr7_seq))); } =20 -static __always_inline void local_db_restore(unsigned long dr7) +static __always_inline void local_db_restore(unsigned long dr7, + unsigned int dr7_seq) { + unsigned long val; + unsigned int seq; + /* * Ensure the compiler doesn't raise this statement into * the critical section; enabling breakpoints early would * not be good. */ barrier(); - if (dr7) - set_debugreg(dr7, 7); + + do { + seq =3D this_cpu_read(cpu_dr7_seq); + if (seq =3D=3D dr7_seq) { + if (!dr7) + return; + val =3D dr7; + } else { + /* + * If an NMI modified breakpoints while DR7 was saved as 0 + * (e.g. KVM guest entry), arch_install_hw_breakpoint() + * clobbered hardware DR7. Restore val =3D 0 (DR7_FIXED_1) + * to clean up the NMI's write and preserve guest isolation. + * Otherwise, load the latest cpu_dr7 state. + */ + val =3D dr7 ? this_cpu_read(cpu_dr7) : 0; + } + + set_debugreg(val | DR7_FIXED_1, 7); + barrier(); + } while (unlikely(seq !=3D this_cpu_read(cpu_dr7_seq))); } =20 #ifdef CONFIG_CPU_SUP_AMD diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c index 39f238952e14..b3669d6f88d4 100644 --- a/arch/x86/kernel/cpu/mce/core.c +++ b/arch/x86/kernel/cpu/mce/core.c @@ -2109,8 +2109,9 @@ static __always_inline void exc_machine_check_kernel(= struct pt_regs *regs) { irqentry_state_t irq_state; unsigned long dr7; + unsigned int dr7_seq; =20 - dr7 =3D local_db_save(); + local_db_save(&dr7, &dr7_seq); =20 WARN_ON_ONCE(user_mode(regs)); =20 @@ -2127,18 +2128,19 @@ static __always_inline void exc_machine_check_kerne= l(struct pt_regs *regs) =20 irqentry_nmi_exit(regs, irq_state); out: - local_db_restore(dr7); + local_db_restore(dr7, dr7_seq); } =20 static __always_inline void exc_machine_check_user(struct pt_regs *regs) { unsigned long dr7; + unsigned int dr7_seq; =20 irqentry_enter_from_user_mode(regs); =20 - dr7 =3D local_db_save(); + local_db_save(&dr7, &dr7_seq); do_machine_check(regs); - local_db_restore(dr7); + local_db_restore(dr7, dr7_seq); =20 irqentry_exit_to_user_mode(regs); } diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoin= t.c index f846c15f21ca..312550be3ad2 100644 --- a/arch/x86/kernel/hw_breakpoint.c +++ b/arch/x86/kernel/hw_breakpoint.c @@ -40,6 +40,9 @@ DEFINE_PER_CPU(unsigned long, cpu_dr7); EXPORT_PER_CPU_SYMBOL(cpu_dr7); =20 +/* Sequence number of the per-CPU DR7 state. */ +DEFINE_PER_CPU(unsigned int, cpu_dr7_seq); + /* Per cpu debug address registers values */ static DEFINE_PER_CPU(unsigned long, cpu_debugreg[HBP_NUM]); =20 @@ -97,38 +100,31 @@ int decode_dr7(unsigned long dr7, int bpnum, unsigned = *len, unsigned *type) int arch_install_hw_breakpoint(struct perf_event *bp) { struct arch_hw_breakpoint *info =3D counter_arch_bp(bp); - unsigned long *dr7; + unsigned int seq; int i; =20 lockdep_assert_irqs_disabled(); =20 for (i =3D 0; i < HBP_NUM; i++) { - struct perf_event **slot =3D this_cpu_ptr(&bp_per_reg[i]); - - if (!*slot) { - *slot =3D bp; + if (!this_cpu_cmpxchg(bp_per_reg[i], NULL, bp)) break; - } } =20 if (WARN_ONCE(i =3D=3D HBP_NUM, "Can't find any breakpoint slot")) return -EBUSY; =20 - set_debugreg(info->address, i); - __this_cpu_write(cpu_debugreg[i], info->address); - - dr7 =3D this_cpu_ptr(&cpu_dr7); - *dr7 |=3D encode_dr7(i, info->len, info->type); - - /* - * Ensure we first write cpu_dr7 before we set the DR7 register. - * This ensures an NMI never see cpu_dr7 0 when DR7 is not. - */ - barrier(); - - set_debugreg(*dr7, 7); - if (info->mask) - amd_set_dr_addr_mask(info->mask, i); + do { + seq =3D this_cpu_inc_return(cpu_dr7_seq); + this_cpu_write(cpu_debugreg[i], info->address); + barrier(); + set_debugreg(info->address, i); + if (info->mask) + amd_set_dr_addr_mask(info->mask, i); + this_cpu_or(cpu_dr7, encode_dr7(i, info->len, info->type)); + barrier(); + set_debugreg(this_cpu_read(cpu_dr7) | DR7_FIXED_1, 7); + barrier(); + } while (seq !=3D this_cpu_read(cpu_dr7_seq)); =20 return 0; } @@ -146,36 +142,34 @@ void arch_uninstall_hw_breakpoint(struct perf_event *= bp) { struct arch_hw_breakpoint *info =3D counter_arch_bp(bp); unsigned long dr7; + unsigned int seq; int i; =20 lockdep_assert_irqs_disabled(); =20 for (i =3D 0; i < HBP_NUM; i++) { - struct perf_event **slot =3D this_cpu_ptr(&bp_per_reg[i]); - - if (*slot =3D=3D bp) { - *slot =3D NULL; + if (this_cpu_read(bp_per_reg[i]) =3D=3D bp) break; - } } =20 if (WARN_ONCE(i =3D=3D HBP_NUM, "Can't find any breakpoint slot")) return; =20 - dr7 =3D this_cpu_read(cpu_dr7); - dr7 &=3D ~__encode_dr7(i, info->len, info->type); - - set_debugreg(dr7, 7); - if (info->mask) - amd_set_dr_addr_mask(0, i); - - /* - * Ensure the write to cpu_dr7 is after we've set the DR7 register. - * This ensures an NMI never see cpu_dr7 0 when DR7 is not. - */ - barrier(); - - this_cpu_write(cpu_dr7, dr7); + do { + seq =3D this_cpu_inc_return(cpu_dr7_seq); + dr7 =3D this_cpu_read(cpu_dr7); + dr7 &=3D ~__encode_dr7(i, info->len, info->type); + set_debugreg(dr7 | DR7_FIXED_1, 7); + if (info->mask) + amd_set_dr_addr_mask(0, i); + barrier(); + this_cpu_and(cpu_dr7, + ~__encode_dr7(i, info->len, info->type)); + barrier(); + } while (seq !=3D this_cpu_read(cpu_dr7_seq)); + + WARN_ONCE(this_cpu_cmpxchg(bp_per_reg[i], bp, NULL) !=3D bp, + "Can't release breakpoint slot"); } =20 static int arch_bp_generic_len(int x86_len) @@ -309,13 +303,14 @@ static inline bool within_cpu_entry(unsigned long add= r, unsigned long end) sizeof(struct tlb_state))) return true; =20 - /* - * When in guest (X86_FEATURE_HYPERVISOR), local_db_save() - * will read per-cpu cpu_dr7 before clear dr7 register. - */ + /* local_db_save() reads this state before clearing DR7. */ if (within_area(addr, end, (unsigned long)&per_cpu(cpu_dr7, cpu), sizeof(cpu_dr7))) return true; + if (within_area(addr, end, + (unsigned long)&per_cpu(cpu_dr7_seq, cpu), + sizeof(cpu_dr7_seq))) + return true; } =20 return false; @@ -483,12 +478,18 @@ void flush_ptrace_hw_breakpoint(struct task_struct *t= sk) =20 void hw_breakpoint_restore(void) { - set_debugreg(__this_cpu_read(cpu_debugreg[0]), 0); - set_debugreg(__this_cpu_read(cpu_debugreg[1]), 1); - set_debugreg(__this_cpu_read(cpu_debugreg[2]), 2); - set_debugreg(__this_cpu_read(cpu_debugreg[3]), 3); - set_debugreg(DR6_RESERVED, 6); - set_debugreg(__this_cpu_read(cpu_dr7), 7); + unsigned int seq; + + do { + seq =3D this_cpu_inc_return(cpu_dr7_seq); + set_debugreg(this_cpu_read(cpu_debugreg[0]), 0); + set_debugreg(this_cpu_read(cpu_debugreg[1]), 1); + set_debugreg(this_cpu_read(cpu_debugreg[2]), 2); + set_debugreg(this_cpu_read(cpu_debugreg[3]), 3); + set_debugreg(DR6_RESERVED, 6); + set_debugreg(this_cpu_read(cpu_dr7) | DR7_FIXED_1, 7); + barrier(); + } while (seq !=3D this_cpu_read(cpu_dr7_seq)); } EXPORT_SYMBOL_FOR_KVM(hw_breakpoint_restore); =20 diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c index 3c9f60d6ca5a..c3806f7bd3e8 100644 --- a/arch/x86/kernel/nmi.c +++ b/arch/x86/kernel/nmi.c @@ -531,11 +531,12 @@ enum nmi_states { }; static DEFINE_PER_CPU(enum nmi_states, nmi_state); static DEFINE_PER_CPU(unsigned long, nmi_cr2); -static DEFINE_PER_CPU(unsigned long, nmi_dr7); =20 DEFINE_IDTENTRY_RAW(exc_nmi) { irqentry_state_t irq_state; + unsigned long dr7; + unsigned int dr7_seq; struct nmi_stats *nsp =3D this_cpu_ptr(&nmi_stats); =20 /* @@ -572,7 +573,7 @@ DEFINE_IDTENTRY_RAW(exc_nmi) */ sev_es_ist_enter(regs); =20 - this_cpu_write(nmi_dr7, local_db_save()); + local_db_save(&dr7, &dr7_seq); =20 irq_state =3D irqentry_nmi_enter(regs); =20 @@ -594,7 +595,7 @@ DEFINE_IDTENTRY_RAW(exc_nmi) =20 irqentry_nmi_exit(regs, irq_state); =20 - local_db_restore(this_cpu_read(nmi_dr7)); + local_db_restore(dr7, dr7_seq); =20 sev_es_ist_exit(); =20 diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 30aa8369957e..018abe736285 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -1231,8 +1231,12 @@ static noinstr void exc_debug_kernel(struct pt_regs = *regs, unsigned long dr6) * it results in an endless recursion and stack overflow. Thus we stay * with the IDT approach, i.e., save DR7 and disable #DB. */ - unsigned long dr7 =3D local_db_save(); - irqentry_state_t irq_state =3D irqentry_nmi_enter(regs); + unsigned long dr7; + unsigned int dr7_seq; + irqentry_state_t irq_state; + + local_db_save(&dr7, &dr7_seq); + irq_state =3D irqentry_nmi_enter(regs); instrumentation_begin(); =20 /* @@ -1289,7 +1293,7 @@ static noinstr void exc_debug_kernel(struct pt_regs *= regs, unsigned long dr6) instrumentation_end(); irqentry_nmi_exit(regs, irq_state); =20 - local_db_restore(dr7); + local_db_restore(dr7, dr7_seq); } =20 static noinstr void exc_debug_user(struct pt_regs *regs, unsigned long dr6) From nobody Sat Sep 26 01:04:32 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 44278345EAC; Mon, 7 Sep 2026 03:46:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788752819; cv=none; b=ZW6I0Va3haEN7Deu+HNYXi3lT7kHZPv1m8UhAUWPZmOoEyyHUarPXvnJGpGz4MwMi54fDHJy0iEtpUkb5NYFthp9BPuSHK/BzxtvVD/DbiREiOTvUcfCxa5KdWle++QnWqX2GbHPdqlNDsaKwO66mMk1nSPn8NGi2qas+U07H/E= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788752819; c=relaxed/simple; bh=N0ZreQGclss/XlCp36inxsdcAfEl7QDQRsoQ/lmAo5o=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=TL2hPTS8ypID68jQsKn+ByhZN0OxoLBMPOO7tpT2PBgVFM5RYUJyaA8AYEElw1fC0mDQhetR4lcQm9C/GOkc/an0b0xG6uUjla+IJsMG13Cu3mXmXgHT9Z3K3PqHbskEReTOP6H1qMfUtVRoq2fKOYrjUMP2pCAEtJ7wjRoU7P0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=PFYCpI2H; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="PFYCpI2H" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 78EB01F00A3A; Mon, 7 Sep 2026 03:46:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788752818; bh=dntm4Dmaxt6c0we5Lair/2EK77dGj1VLD5czr613kwE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=PFYCpI2HXe9bQyxDbarRNynnun5ILuG/lpKi2dePIlRg/n2C1i+F4nwA4R8wnNn1i VOONOt+EdlA2GHnEvdaO1Ohln3Tt583MYWNxo4mnsYAJlRK6aWFzkpnU4cj41lnkje kUuKcgv+XXt0LVKm1pDAD89a1MJq3uRHNv/jrbPTXii7G72UbKPBON3B7Ot3HjkyIv sVhTf/b8gxhGoWdSNARXUq+64/w3ZAovgTuhDTDcOv0gJnzQfFv/aMuq6IhyEO5+lb 5w0VxoG8BHQKq3k9iTNzwYfpy48LDaoHgSWxJWKM5lFeNj9pj8uFk874evw3Laczgx jEgyRkiBGD7eA== From: "Masami Hiramatsu (Google)" To: Steven Rostedt , Peter Zijlstra , Ingo Molnar , x86@kernel.org Cc: Jinchao Wang , Mathieu Desnoyers , Masami Hiramatsu , Thomas Gleixner , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Alexander Shishkin , Ian Rogers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: [PATCH v15 03/12] x86/hw_breakpoints: Add arch_modify_local_hw_breakpoint_addr() API Date: Mon, 7 Sep 2026 12:46:52 +0900 Message-ID: <178875281237.93794.4844650709915505895.stgit@devnote2> X-Mailer: git-send-email 2.43.0 In-Reply-To: <178875277830.93794.14247844688761142429.stgit@devnote2> References: <178875277830.93794.14247844688761142429.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Jinchao Wang Wprobe needs to move an active per-CPU watchpoint without releasing and reserving its hardware slot. Add arch_modify_local_hw_breakpoint_addr() as the architecture backend for modify_local_hw_breakpoint_addr(). It validates the new address, finds the installed local slot, and updates the hardware debug register and per-CPU shadow register. The core layer (modify_local_hw_breakpoint_addr()) handles updating bp->attr.bp_addr and counter_arch_bp(bp)->address. The caller must provide an installed local event and a valid address. Slot ownership, breakpoint type, length, mask and DR7 remain unchanged. Link: https://lore.kernel.org/all/59637b96946653393a7ad3c7de094094796b39c2.= 1785067572.git.wangjinchao600@gmail.com/ Assisted-by: Antigravity:gemini-3.8-flash Signed-off-by: Jinchao Wang Signed-off-by: Masami Hiramatsu (Google) --- Changes in v15: - Temporarily clear the breakpoint enable bit in DR7 before updating the debug address register, and re-enable it afterward, to comply with the x86 hardware specification and avoid spurious #DB exceptions. Changes in v13: - Add compiler barrier (barrier()) before checking cpu_dr7_seq to prevent hoisting the sequence check before set_debugreg(). - Clarify in commit log and code comment that the core layer manages updating bp->attr.bp_addr and counter_arch_bp(bp)->address. Changes in v11: - Return int error code instead of void. - Validate the new address using hw_breakpoint_arch_parse() before updating registers. - Increment cpu_dr7_seq in a sequence loop for NMI protection. - Return -ENOENT if the breakpoint slot is not found on the local CPU. --- arch/x86/include/asm/hw_breakpoint.h | 2 + arch/x86/kernel/hw_breakpoint.c | 56 ++++++++++++++++++++++++++++++= ++++ 2 files changed, 58 insertions(+) diff --git a/arch/x86/include/asm/hw_breakpoint.h b/arch/x86/include/asm/hw= _breakpoint.h index 0bc931cd0698..f35ec491f6dd 100644 --- a/arch/x86/include/asm/hw_breakpoint.h +++ b/arch/x86/include/asm/hw_breakpoint.h @@ -59,6 +59,8 @@ extern int hw_breakpoint_exceptions_notify(struct notifie= r_block *unused, =20 =20 int arch_install_hw_breakpoint(struct perf_event *bp); +int arch_modify_local_hw_breakpoint_addr(struct perf_event *bp, + unsigned long addr); void arch_uninstall_hw_breakpoint(struct perf_event *bp); void hw_breakpoint_pmu_read(struct perf_event *bp); void hw_breakpoint_pmu_unthrottle(struct perf_event *bp); diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoin= t.c index 312550be3ad2..99f0926298a8 100644 --- a/arch/x86/kernel/hw_breakpoint.c +++ b/arch/x86/kernel/hw_breakpoint.c @@ -129,6 +129,62 @@ int arch_install_hw_breakpoint(struct perf_event *bp) return 0; } =20 +/* + * Modify the address of an installed perf counter breakpoint on local CPU. + * + * This updates the debug address register and per-CPU shadow state without + * changing slot allocation or DR7. The core layer (modify_local_hw_breakp= oint_addr()) + * manages updating bp->attr.bp_addr and counter_arch_bp(bp)->address. + * + * Atomic: called with IRQs disabled and handles variables and registers + * local to this CPU. + */ +int arch_modify_local_hw_breakpoint_addr(struct perf_event *bp, + unsigned long addr) +{ + struct arch_hw_breakpoint *info =3D counter_arch_bp(bp); + struct arch_hw_breakpoint hw; + struct perf_event_attr attr =3D bp->attr; + unsigned long dr7; + unsigned int seq; + int i, ret; + + lockdep_assert_irqs_disabled(); + + attr.bp_addr =3D addr; + ret =3D hw_breakpoint_arch_parse(bp, &attr, &hw); + if (ret) + return ret; + + for (i =3D 0; i < HBP_NUM; i++) { + if (this_cpu_read(bp_per_reg[i]) =3D=3D bp) + break; + } + + if (WARN_ONCE(i =3D=3D HBP_NUM, "Can't find any breakpoint slot")) + return -ENOENT; + + do { + seq =3D this_cpu_inc_return(cpu_dr7_seq); + + /* Disable breakpoint in DR7 before updating address register */ + dr7 =3D this_cpu_read(cpu_dr7); + set_debugreg((dr7 & ~__encode_dr7(i, info->len, info->type)) | DR7_FIXED= _1, 7); + barrier(); + + this_cpu_write(cpu_debugreg[i], addr); + barrier(); + set_debugreg(addr, i); + barrier(); + + /* Re-enable breakpoint in DR7 */ + set_debugreg(this_cpu_read(cpu_dr7) | DR7_FIXED_1, 7); + barrier(); + } while (seq !=3D this_cpu_read(cpu_dr7_seq)); + + return 0; +} + /* * Uninstall the breakpoint contained in the given counter. * From nobody Sat Sep 26 01:04:32 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 63BB73E92BD; Mon, 7 Sep 2026 03:47:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788752830; cv=none; b=u3A8TfQCGLz4r/cjYADN7h+RQwSqfod0eaEi8NtkTh6joQSp/vsrHxEkOPycKK4wm/I2UXQmaWFC3iVLouBYcHyxha3eVJvy9W1aN+GhlrEHqeidFJEpmKKzQautW698AZdchsnXb+Fu9QoaHft1Rc8TVkHTHt2VDdBjpyJSejI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788752830; c=relaxed/simple; bh=WSSazbM+fHfaUAOgnSMHO0iUtKbGi34yU9nXSmgXbfI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=oA8uL3QFXL9w0MV6kz7Fyfd9+obTIqKKCf8sLAepRVpVykk+/hy4KfCFGK5XFqCobAUGf4Xau4myAYoTtNVxu/lN3z71e0AsHQyqVTjPMmSDmdpWZGsivnyQWGGt/GODJFtrifqkObtB76cVRb4oempCAvy0s68eaykfjD15TsA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JvWwwKLn; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="JvWwwKLn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A05FA1F00A3A; Mon, 7 Sep 2026 03:47:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788752829; bh=jQqBZgRQel9T6CKiVbYZiYgcese2NqaCIfPTKivOYNM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=JvWwwKLnv5R/49t4Ovb/Dz38meIFEnSADxPf0oo/ZqKuspHteNKS3PMkLHGANHjo8 08kDAus2B1OQXDvbgakS+QESh0KvDQb4J8uMjUmyG5rjKdhM403okCfjsk1pPZKHB6 94qNJ/hSo0vp7U/OUVkikjkg1mSI3efo45Q3mKikXZA+WPN9WHnIC7n7tlnG/ehek5 oMdNgSP8rGCmv4D1+Hz7eK1axj1x4IBJuCPSjhQVAygViw9oStULklkaklZcMG4kFs pvs6UDSJKgSZ3RPQXmrbMAvQeyGucJD1L4y8PsdfazuG5OYImUX/ExpNbroP+7+aeM 4mNyjCcpW7W8Q== From: "Masami Hiramatsu (Google)" To: Steven Rostedt , Peter Zijlstra , Ingo Molnar , x86@kernel.org Cc: Jinchao Wang , Mathieu Desnoyers , Masami Hiramatsu , Thomas Gleixner , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Alexander Shishkin , Ian Rogers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: [PATCH v15 04/12] HWBP: Add modify_local_hw_breakpoint_addr() API Date: Mon, 7 Sep 2026 12:47:03 +0900 Message-ID: <178875282353.93794.1882454863588931285.stgit@devnote2> X-Mailer: git-send-email 2.43.0 In-Reply-To: <178875277830.93794.14247844688761142429.stgit@devnote2> References: <178875277830.93794.14247844688761142429.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Masami Hiramatsu (Google) Add modify_local_hw_breakpoint_addr() to update only the watched address of an installed hardware breakpoint on the local CPU without releasing and reserving its hardware slot. This is available when the architecture selects CONFIG_HAVE_MODIFY_LOCAL_HW_BREAKPOINT_ADDR. The caller must provide an installed local event and a valid address, and update other CPUs separately. Link: https://lore.kernel.org/all/f9c49dfa49bdc57ba8c0574bc9981c1e581acf92.= 1785067572.git.wangjinchao600@gmail.com/ Assisted-by: Antigravity:gemini-3.8-flash Signed-off-by: Masami Hiramatsu (Google) Signed-off-by: Jinchao Wang --- Changes in v15: - Use WRITE_ONCE() for counter_arch_bp(bp)->address and bp->attr.bp_addr in both update and rollback paths to prevent data races with concurrent readers (e.g. NMI handlers). Changes in v13: - Add comment to modify_local_hw_breakpoint_addr() clarifying the early update behavior of bp->attr.bp_addr during the NMI race window. Changes in v12: - Update bp->attr.bp_addr and counter_arch_bp(bp)->address before calling arch_modify_local_hw_breakpoint_addr() to prevent race conditions during interrupt handling. - Restore counter_arch_bp(bp)->address and bp->attr.bp_addr if arch_modify_local_hw_breakpoint_addr() fails. Changes in v11: - Check return value of arch_modify_local_hw_breakpoint_addr() and return error on failure. - Update bp->attr.bp_addr and counter_arch_bp(bp)->address only after arch modification succeeds. --- arch/Kconfig | 8 +++++++ arch/x86/Kconfig | 1 + include/linux/hw_breakpoint.h | 6 +++++ kernel/events/hw_breakpoint.c | 48 +++++++++++++++++++++++++++++++++++++= ++++ 4 files changed, 63 insertions(+) diff --git a/arch/Kconfig b/arch/Kconfig index 45c657772362..d021bc31ef14 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -474,6 +474,14 @@ config HAVE_MIXED_BREAKPOINTS_REGS Select this option if your arch implements breakpoints under the latter fashion. =20 +config HAVE_MODIFY_LOCAL_HW_BREAKPOINT_ADDR + bool + depends on HAVE_HW_BREAKPOINT + help + Select this if the architecture can modify the address of an + installed hardware breakpoint on the local CPU without releasing + and reserving its hardware slot. + config HAVE_USER_RETURN_NOTIFIER bool =20 diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 15fd9ec5ecac..38e29e465022 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -249,6 +249,7 @@ config X86 select HAVE_FUNCTION_TRACER select HAVE_GCC_PLUGINS select HAVE_HW_BREAKPOINT + select HAVE_MODIFY_LOCAL_HW_BREAKPOINT_ADDR select HAVE_IOREMAP_PROT select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 select HAVE_IRQ_TIME_ACCOUNTING diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h index db199d653dd1..bf65c7fffd99 100644 --- a/include/linux/hw_breakpoint.h +++ b/include/linux/hw_breakpoint.h @@ -81,6 +81,9 @@ register_wide_hw_breakpoint(struct perf_event_attr *attr, perf_overflow_handler_t triggered, void *context); =20 +int modify_local_hw_breakpoint_addr(struct perf_event *bp, + unsigned long addr); + extern int register_perf_hw_breakpoint(struct perf_event *bp); extern void unregister_hw_breakpoint(struct perf_event *bp); extern void unregister_wide_hw_breakpoint(struct perf_event * __percpu *cp= u_events); @@ -124,6 +127,9 @@ register_wide_hw_breakpoint(struct perf_event_attr *att= r, perf_overflow_handler_t triggered, void *context) { return NULL; } static inline int +modify_local_hw_breakpoint_addr(struct perf_event *bp, + unsigned long addr) { return -EOPNOTSUPP; } +static inline int register_perf_hw_breakpoint(struct perf_event *bp) { return -ENOSYS; } static inline void unregister_hw_breakpoint(struct perf_event *bp) { } static inline void diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c index 789add0c185a..69bfb17b87c4 100644 --- a/kernel/events/hw_breakpoint.c +++ b/kernel/events/hw_breakpoint.c @@ -888,6 +888,54 @@ void unregister_wide_hw_breakpoint(struct perf_event *= __percpu *cpu_events) } EXPORT_SYMBOL_GPL(unregister_wide_hw_breakpoint); =20 +/** + * modify_local_hw_breakpoint_addr - update a local breakpoint address + * @bp: the hwbp perf event for this CPU + * @addr: the new address for @bp + * + * Update only the address of an installed breakpoint on the local CPU wit= hout + * releasing and reserving its hardware slot. The caller must update other= CPUs. + * Return 0, or -EOPNOTSUPP if the architecture does not support this oper= ation. + * + * Note: bp->attr.bp_addr and counter_arch_bp(bp)->address are updated bef= ore + * modifying hardware registers so that interrupt/NMI handlers and CPU ent= ry + * paths observe the new address during the transition. If an NMI hits the= old + * breakpoint address before the hardware register update finishes, the ev= ent + * handler will see bp->attr.bp_addr already pointing to @addr. If the + * architecture update fails, both are rolled back to the previous address. + * Callers must be prepared for this behavior. + */ +#ifdef CONFIG_HAVE_MODIFY_LOCAL_HW_BREAKPOINT_ADDR +int modify_local_hw_breakpoint_addr(struct perf_event *bp, + unsigned long addr) +{ + unsigned long old_addr; + int ret; + + lockdep_assert_irqs_disabled(); + + old_addr =3D bp->attr.bp_addr; + WRITE_ONCE(counter_arch_bp(bp)->address, addr); + WRITE_ONCE(bp->attr.bp_addr, addr); + + ret =3D arch_modify_local_hw_breakpoint_addr(bp, addr); + if (ret) { + WRITE_ONCE(counter_arch_bp(bp)->address, old_addr); + WRITE_ONCE(bp->attr.bp_addr, old_addr); + return ret; + } + + return 0; +} +#else +int modify_local_hw_breakpoint_addr(struct perf_event *bp, + unsigned long addr) +{ + return -EOPNOTSUPP; +} +#endif +EXPORT_SYMBOL_GPL(modify_local_hw_breakpoint_addr); + /** * hw_breakpoint_is_used - check if breakpoints are currently used * From nobody Sat Sep 26 01:04:32 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 D77453ED3BA; Mon, 7 Sep 2026 03:47:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788752843; cv=none; b=oCWGeOD6bGQsO5+D5ByALpHflr3kjpF6Qhcp3ScZdKrd7Lf9MOGbYiqnl7HFNcqi6dYJFUy56eMI6IV8HFYrC9G8fMMUsHgUOMp4HJ+5vdtEUBs7bBS0dUBLzP8OZFgi7/zOa0Zu17e9iqSLQvs/axSMWHQzGzR8qqdvZW8uJh0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788752843; c=relaxed/simple; bh=DMNZRa2SULk6PmpdDkqhExC+xDrbONr7IC70QnRM6Es=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=YMsKcPAWdH/EgFbNIZcaHfqLsxc67Bzk3wO7NCkZJLunZeZrEp+ki1bJmm2ZzzdnLEDW9nXfsmDoRXukxUtPqmvkQh2NO0HrrZUV0EzF+5ojx5ql6th1O2k2aH96JfR+sM02MHoe/ZPS5xptFCK4zurITiI3Eb2V2MrUB04Rfoc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZHnOPTcp; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ZHnOPTcp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E0C941F00A3A; Mon, 7 Sep 2026 03:47:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788752840; bh=QhTRR5Tu23CnD0e0DuhkB/4GoGieOljVCbnF8K+MmNA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ZHnOPTcpbiMiy7MjhdljbSfnt9RPx1nEYimp6QosE912eewkD+Jga0VNspS36NPck dn4Ex4iV7Est/vQ7C6ECin6NNvEHAQH+nr1NHlCkBFN7Tl57/UPDCvX2d4VzAg1JB5 QDTp4Aocm308D0Lhs/2C0f04IGPG8ctPGLPQo/E1ZssifWWPKwqooOg/ToMUOlzI72 Q7ya5cmgQXyHgCf78FNZ25Jh4oR4lslVlQbTvXbcEi/4qlcgnTtzI1q5IIVr6aIFWX i1B8kENms1moW3y6m12I9RYAQ4CCmuEYcQUVTKMCOSnpbgwbpLmx8FOsgCoCk39noL +knTmUP0Mxp2A== From: "Masami Hiramatsu (Google)" To: Steven Rostedt , Peter Zijlstra , Ingo Molnar , x86@kernel.org Cc: Jinchao Wang , Mathieu Desnoyers , Masami Hiramatsu , Thomas Gleixner , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Alexander Shishkin , Ian Rogers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: [PATCH v15 05/12] tracing/wprobe: Add wprobe (watchpoint probe) trace event support Date: Mon, 7 Sep 2026 12:47:14 +0900 Message-ID: <178875283469.93794.8082169522481243792.stgit@devnote2> X-Mailer: git-send-email 2.43.0 In-Reply-To: <178875277830.93794.14247844688761142429.stgit@devnote2> References: <178875277830.93794.14247844688761142429.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Masami Hiramatsu (Google) Add hardware-breakpoint-based dynamic trace event support (wprobe). Wprobe creates a dynamic event on data read/write accesses using hardware breakpoints and logs the access context and fetchargs. Link: https://lore.kernel.org/all/59637b96946653393a7ad3c7de094094796b39c2.= 1785067572.git.wangjinchao600@gmail.com/ Assisted-by: Antigravity:gemini-3.8-flash Signed-off-by: Masami Hiramatsu (Google) --- Changes in v15: - Introduce trace_wprobe_is_valid_addr() to validate target address and natural alignment for wprobe length during event creation. - Move local variable declarations to function entry in trace_wprobe_show() to comply with kernel C coding standards. - Fix indentation in kernel/trace/trace.c to use tabs instead of spaces. Changes in v14: - In parse_address_spec(), reject address 0 and user-space addresses by changing the check to '_addr < TASK_SIZE'. - In trace_wprobe_show(), format symbol and offset explicitly instead of using '%pS' to ensure dynamic event restoration works properly. - Add offset field to struct trace_wprobe and pass it to alloc_trace_wprobe(). Changes in v13: - Fix documentation notation to SYMBOL[+|-OFFS] as same as others. - Fix documentation indents and add default value. - Fix README file to add []. - Add a note about module unloading. Changes in v12: - Fix syntax comment typo ('b' to 'w') and remove dead 'ret =3D 0' initialization in __trace_wprobe_create(). - Fix documentation notation to SYMBOL[[+|-]OFFS]. Changes in v11: - Add trace_wprobe_is_busy() to prevent releasing busy events. Changes in v9: - Use kzalloc_flex for alloc_trace_wprobe. --- Documentation/trace/index.rst | 1=20 Documentation/trace/wprobetrace.rst | 78 ++++ include/linux/trace_events.h | 2=20 kernel/trace/Kconfig | 13 + kernel/trace/Makefile | 1=20 kernel/trace/trace.c | 9=20 kernel/trace/trace.h | 5=20 kernel/trace/trace_probe.c | 21 + kernel/trace/trace_probe.h | 10=20 kernel/trace/trace_wprobe.c | 775 +++++++++++++++++++++++++++++++= ++++ 10 files changed, 911 insertions(+), 4 deletions(-) create mode 100644 Documentation/trace/wprobetrace.rst create mode 100644 kernel/trace/trace_wprobe.c diff --git a/Documentation/trace/index.rst b/Documentation/trace/index.rst index f4058e8e92e3..4f3fa60e4ecd 100644 --- a/Documentation/trace/index.rst +++ b/Documentation/trace/index.rst @@ -36,6 +36,7 @@ the Linux kernel. kprobes kprobetrace fprobetrace + wprobetrace eprobetrace fprobe ring-buffer-design diff --git a/Documentation/trace/wprobetrace.rst b/Documentation/trace/wpro= betrace.rst new file mode 100644 index 000000000000..31cc68b464e9 --- /dev/null +++ b/Documentation/trace/wprobetrace.rst @@ -0,0 +1,78 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D +Watchpoint probe (wprobe) Event Tracing +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D + +.. Author: Masami Hiramatsu + +Overview +-------- + +Wprobe event is a dynamic event based on the hardware breakpoint, which is +similar to other probe events, but it is for watching data access. It allo= ws +you to trace which code accesses a specified data. + +As same as other dynamic events, wprobe events are defined via +`dynamic_events` interface file on tracefs. + +Synopsis of wprobe-events +------------------------- +:: + + w:[GRP/][EVENT] SPEC [FETCHARGS] : Probe on data a= ccess + + GRP : Group name for wprobe. If omitted, use "wprobes" for it. + EVENT : Event name for wprobe. If omitted, an event name is + generated based on the address or symbol. + SPEC : Breakpoint specification. + [r|w|rw]@[:LENGTH] + + r|w|rw : Access type, r for read, w for write, and rw for both. + Default is rw if omitted. + ADDRESS : Address to watch (hexadecimal). MUST be in kernel space. + SYMBOL[+|-OFFS] : Symbol name to watch. (Optional positive/negative off= set) + LENGTH : Length of the data to watch in bytes. (1, 2, 4, or 8) + Default is 4. + + FETCHARGS : Arguments. Each probe can have up to 128 args. + $addr : Fetch the accessing address. + $value : Fetch the memory value at the accessing address (same a= s +0($addr)). + @ADDR : Fetch memory at ADDR (ADDR should be in kernel) + @SYM[+|-offs] : Fetch memory at SYM +|- offs (SYM should be a data symb= ol) + +|-[u]OFFS(FETCHARG) : Fetch memory at FETCHARG +|- OFFS address.(\*1)(= \*2) + \IMM : Store an immediate value to the argument. + NAME=3DFETCHARG : Set NAME as the argument name of FETCHARG. + FETCHARG:TYPE : Set TYPE as the type of FETCHARG. Currently, basic types + (u8/u16/u32/u64/s8/s16/s32/s64), hexadecimal types + (x8/x16/x32/x64), "char", "string", "ustring", "symbol",= "symstr" + and bitfield are supported. + + (\*1) This is useful for fetching a field of data structures. + (\*2) "u" means user-space dereference. + +For the details of TYPE, see :ref:`kprobetrace documentation `. + +Usage examples +-------------- +Here is an example to add a wprobe event on a variable `jiffies`. +:: + + # echo 'w:my_jiffies w@jiffies' >> dynamic_events + # cat dynamic_events + w:wprobes/my_jiffies w@jiffies + # echo 1 > events/wprobes/enable + # cat trace | head + # TASK-PID CPU# ||||| TIMESTAMP FUNCTION + # | | | ||||| | | + -0 [000] d.Z1. 717.026259: my_jiffies: (tick_do_up= date_jiffies64+0xbe/0x130) + -0 [000] d.Z1. 717.026373: my_jiffies: (tick_do_up= date_jiffies64+0xbe/0x130) + +You can see the code which writes to `jiffies` is `tick_do_update_jiffies6= 4()`. + +Notes +----- +Wprobe event does not disable itself even if the module is unloaded. +For example, if you add a wprobe event on a module variable, and then +unload the module, the wprobe event will still be enabled. This is for +watching the address is used unexpectedly after the module is unloaded. diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h index 5cbd09c8be8d..43ffd9a76d88 100644 --- a/include/linux/trace_events.h +++ b/include/linux/trace_events.h @@ -337,6 +337,7 @@ enum { TRACE_EVENT_FL_UPROBE_BIT, TRACE_EVENT_FL_EPROBE_BIT, TRACE_EVENT_FL_FPROBE_BIT, + TRACE_EVENT_FL_WPROBE_BIT, TRACE_EVENT_FL_CUSTOM_BIT, TRACE_EVENT_FL_TEST_STR_BIT, }; @@ -367,6 +368,7 @@ enum { TRACE_EVENT_FL_UPROBE =3D (1 << TRACE_EVENT_FL_UPROBE_BIT), TRACE_EVENT_FL_EPROBE =3D (1 << TRACE_EVENT_FL_EPROBE_BIT), TRACE_EVENT_FL_FPROBE =3D (1 << TRACE_EVENT_FL_FPROBE_BIT), + TRACE_EVENT_FL_WPROBE =3D (1 << TRACE_EVENT_FL_WPROBE_BIT), TRACE_EVENT_FL_CUSTOM =3D (1 << TRACE_EVENT_FL_CUSTOM_BIT), TRACE_EVENT_FL_TEST_STR =3D (1 << TRACE_EVENT_FL_TEST_STR_BIT), }; diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index 0ab5916575a9..b58c2565024f 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -862,6 +862,19 @@ config EPROBE_EVENTS convert the type of an event field. For example, turn an address into a string. =20 +config WPROBE_EVENTS + bool "Enable wprobe-based dynamic events" + depends on TRACING + depends on HAVE_HW_BREAKPOINT + select PROBE_EVENTS + select DYNAMIC_EVENTS + help + This allows the user to add watchpoint tracing events based on + hardware breakpoints on the fly via the ftrace interface. + + Those events can be inserted wherever hardware breakpoints can be + set, and record accessed memory address and values. + config BPF_EVENTS depends on BPF_SYSCALL depends on (KPROBE_EVENTS || UPROBE_EVENTS) && PERF_EVENTS diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile index f934ff586bd4..141c8323de20 100644 --- a/kernel/trace/Makefile +++ b/kernel/trace/Makefile @@ -126,6 +126,7 @@ obj-$(CONFIG_FTRACE_RECORD_RECURSION) +=3D trace_recurs= ion_record.o obj-$(CONFIG_FPROBE) +=3D fprobe.o obj-$(CONFIG_RETHOOK) +=3D rethook.o obj-$(CONFIG_FPROBE_EVENTS) +=3D trace_fprobe.o +obj-$(CONFIG_WPROBE_EVENTS) +=3D trace_wprobe.o =20 obj-$(CONFIG_TRACEPOINT_BENCHMARK) +=3D trace_benchmark.o obj-$(CONFIG_RV) +=3D rv/ diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index a946e0183fd1..40c3e1543f6e 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4294,8 +4294,12 @@ static const char readme_msg[] =3D " uprobe_events\t\t- Create/append/remove/show the userspace dynamic eve= nts\n" "\t\t\t Write into this file to define/undefine new trace events.\n" #endif +#ifdef CONFIG_WPROBE_EVENTS + " wprobe_events\t\t- Create/append/remove/show the hardware breakpoint d= ynamic events\n" + "\t\t\t Write into this file to define/undefine new trace events.\n" +#endif #if defined(CONFIG_KPROBE_EVENTS) || defined(CONFIG_UPROBE_EVENTS) || \ - defined(CONFIG_FPROBE_EVENTS) + defined(CONFIG_FPROBE_EVENTS) || defined(CONFIG_WPROBE_EVENTS) "\t accepts: event-definitions (one definition per line)\n" #if defined(CONFIG_KPROBE_EVENTS) || defined(CONFIG_UPROBE_EVENTS) "\t Format: p[:[/][]] []\n" @@ -4305,6 +4309,9 @@ static const char readme_msg[] =3D "\t f[:[/][]] [%return] []\n" "\t t[:[/][]] []\n" #endif +#ifdef CONFIG_WPROBE_EVENTS + "\t w[:[/][]] [r|w|rw]@[:] []\n" +#endif #ifdef CONFIG_HIST_TRIGGERS "\t s:[synthetic/] []\n" #endif diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 74a7a50d1e78..18588c550a98 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -179,6 +179,11 @@ struct fexit_trace_entry_head { unsigned long ret_ip; }; =20 +struct wprobe_trace_entry_head { + struct trace_entry ent; + unsigned long ip; +}; + #define TRACE_BUF_SIZE 1024 =20 struct trace_array; diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c index 804442b2f7d2..64e7e363e8e2 100644 --- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c @@ -1403,6 +1403,23 @@ static int parse_probe_vars(char *orig_arg, const st= ruct fetch_type *t, return 0; } =20 + /* wprobe only support "$addr" and "$value" variable */ + if (ctx->flags & TPARG_FL_WPROBE) { + if (!strcmp(arg, "addr")) { + code->op =3D FETCH_OP_BADDR; + return 0; + } + if (!strcmp(arg, "value")) { + code->op =3D FETCH_OP_BADDR; + code++; + code->op =3D FETCH_OP_DEREF; + code->offset =3D 0; + *pcode =3D code; + return 0; + } + goto inval; + } + if (strcmp(arg, "comm") =3D=3D 0 || strcmp(arg, "COMM") =3D=3D 0) { code->op =3D FETCH_OP_COMM; return 0; @@ -1462,8 +1479,8 @@ static int parse_probe_arg_register(char *arg, struct= fetch_insn *code, { int ret; =20 - if (ctx->flags & (TPARG_FL_TEVENT | TPARG_FL_FPROBE)) { - /* eprobe and fprobe do not handle registers */ + if (ctx->flags & (TPARG_FL_TEVENT | TPARG_FL_FPROBE | TPARG_FL_WPROBE)) { + /* eprobe, fprobe and wprobe do not handle registers */ trace_probe_log_err(ctx->offset, BAD_VAR); return -EINVAL; } diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h index d1fb3520700f..f20cafb87cc6 100644 --- a/kernel/trace/trace_probe.h +++ b/kernel/trace/trace_probe.h @@ -90,6 +90,7 @@ typedef int (*print_type_func_t)(struct trace_seq *, void= *, void *); FETCH_OP(STACK, param), /* Stack: .param =3D index */ \ FETCH_OP(STACKP, none), /* Stack pointer */ \ FETCH_OP(RETVAL, none), /* Return value */ \ + FETCH_OP(BADDR, none), /* Break address */ \ FETCH_OP(IMM, imm), /* Immediate: .immediate */ \ FETCH_OP(COMM, none), /* Current comm */ \ FETCH_OP(CURRENT, none), /* Current task_struct address */\ @@ -420,6 +421,7 @@ static inline int traceprobe_get_entry_data_size(struct= trace_probe *tp) #define TPARG_FL_USER BIT(4) #define TPARG_FL_FPROBE BIT(5) #define TPARG_FL_TPOINT BIT(6) +#define TPARG_FL_WPROBE BIT(7) #define TPARG_FL_LOC_MASK GENMASK(4, 0) =20 static inline bool tparg_is_function_entry(unsigned int flags) @@ -546,6 +548,10 @@ extern int traceprobe_define_arg_fields(struct trace_e= vent_call *event_call, C(ARG_TOO_LONG, "Argument expression is too long"), \ C(ARRAY_NO_CLOSE, "Array is not closed"), \ C(ARRAY_TOO_BIG, "Array number is too big"), \ + C(BAD_ACCESS_ADDR, "Invalid access memory address"), \ + C(BAD_ACCESS_FMT, "Access memory address requires @"), \ + C(BAD_ACCESS_LEN, "This memory access length is not supported"), \ + C(BAD_ACCESS_TYPE, "Bad memory access type"), \ C(BAD_ADDR_SUFFIX, "Invalid probed address suffix"), \ C(BAD_ARG_NAME, "Argument name must follow the same rules as C identifie= rs"), \ C(BAD_ARG_NUM, "Invalid argument number"), \ @@ -628,7 +634,9 @@ extern int traceprobe_define_arg_fields(struct trace_ev= ent_call *event_call, C(TYPECAST_NOT_EVENT, "Typecasts are only for eprobe fields"), \ C(TYPECAST_REQ_FIELD, "Typecast requires a field access"), \ C(TYPECAST_SYM_OFFSET, "@SYM+/-OFFSET with typecast needs parentheses"), \ - C(USED_ARG_NAME, "This argument name is already used"), + C(USED_ARG_NAME, "This argument name is already used"), \ + C(WPROBE_NO_MAXACT, "Watchpoint probe does not support maxactive"), \ + C(WPROBE_NO_SIBLING, "Watchpoint probe does not support sibling probes"), =20 #undef C #define C(a, b) TP_ERR_##a diff --git a/kernel/trace/trace_wprobe.c b/kernel/trace/trace_wprobe.c new file mode 100644 index 000000000000..9c6100b63e8d --- /dev/null +++ b/kernel/trace/trace_wprobe.c @@ -0,0 +1,775 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Hardware-breakpoint-based tracing events + * + * Copyright (C) 2023, Masami Hiramatsu + */ +#define pr_fmt(fmt) "trace_wprobe: " fmt + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include + +#include "trace_dynevent.h" +#include "trace_probe.h" +#include "trace_probe_kernel.h" +#include "trace_probe_tmpl.h" +#include "trace_output.h" + +#define WPROBE_EVENT_SYSTEM "wprobes" + +static int trace_wprobe_create(const char *raw_command); +static int trace_wprobe_show(struct seq_file *m, struct dyn_event *ev); +static int trace_wprobe_release(struct dyn_event *ev); +static bool trace_wprobe_is_busy(struct dyn_event *ev); +static bool trace_wprobe_match(const char *system, const char *event, + int argc, const char **argv, struct dyn_event *ev); + +static struct dyn_event_operations trace_wprobe_ops =3D { + .create =3D trace_wprobe_create, + .show =3D trace_wprobe_show, + .is_busy =3D trace_wprobe_is_busy, + .free =3D trace_wprobe_release, + .match =3D trace_wprobe_match, +}; + +struct trace_wprobe { + struct dyn_event devent; + struct perf_event * __percpu *bp_event; + unsigned long addr; + int offset; + int len; + int type; + const char *symbol; + struct trace_probe tp; +}; + +static bool is_trace_wprobe(struct dyn_event *ev) +{ + return ev->ops =3D=3D &trace_wprobe_ops; +} + +static struct trace_wprobe *to_trace_wprobe(struct dyn_event *ev) +{ + return container_of(ev, struct trace_wprobe, devent); +} + +#define for_each_trace_wprobe(pos, dpos) \ + for_each_dyn_event(dpos) \ + if (is_trace_wprobe(dpos) && (pos =3D to_trace_wprobe(dpos))) + +static bool trace_wprobe_is_busy(struct dyn_event *ev) +{ + struct trace_wprobe *tw =3D to_trace_wprobe(ev); + + return trace_probe_is_enabled(&tw->tp); +} + +static bool trace_wprobe_match(const char *system, const char *event, + int argc, const char **argv, struct dyn_event *ev) +{ + struct trace_wprobe *tw =3D to_trace_wprobe(ev); + + if (event[0] !=3D '\0' && strcmp(trace_probe_name(&tw->tp), event)) + return false; + + if (system && strcmp(trace_probe_group_name(&tw->tp), system)) + return false; + + return trace_probe_match_command_args(&tw->tp, argc, argv); +} + +/* + * Note that we don't verify the fetch_insn code, since it does not come + * from user space. + */ +static int +process_fetch_insn(struct fetch_insn *code, void *rec, void *edata, + void *dest, void *base) +{ + void *baddr =3D rec; + unsigned long val; + int ret; + +retry: + /* 1st stage: get value from context */ + switch (code->op) { + case FETCH_OP_BADDR: + val =3D (unsigned long)baddr; + break; + case FETCH_NOP_SYMBOL: /* Ignore a place holder */ + code++; + goto retry; + default: + ret =3D process_common_fetch_insn(code, &val); + if (ret < 0) + return ret; + } + code++; + + return process_fetch_insn_bottom(code, val, dest, base); +} +NOKPROBE_SYMBOL(process_fetch_insn) + +static void wprobe_trace_handler(struct trace_wprobe *tw, + unsigned long addr, + struct pt_regs *regs, + struct trace_event_file *trace_file) +{ + struct wprobe_trace_entry_head *entry; + struct trace_event_call *call =3D trace_probe_event_call(&tw->tp); + struct trace_event_buffer fbuffer; + int dsize; + + if (WARN_ON_ONCE(call !=3D trace_file->event_call)) + return; + + if (trace_trigger_soft_disabled(trace_file)) + return; + + if (READ_ONCE(tw->addr) !=3D addr) + return; + + dsize =3D __get_data_size(&tw->tp, (void *)addr, NULL); + + entry =3D trace_event_buffer_reserve(&fbuffer, trace_file, + sizeof(*entry) + tw->tp.size + dsize); + if (!entry) + return; + + entry->ip =3D instruction_pointer(regs); + store_trace_args(&entry[1], &tw->tp, (void *)addr, NULL, sizeof(*entry), = dsize); + + fbuffer.regs =3D regs; + trace_event_buffer_commit(&fbuffer); +} + +static void wprobe_perf_handler(struct perf_event *bp, + struct perf_sample_data *data, + struct pt_regs *regs) +{ + struct trace_wprobe *tw =3D bp->overflow_handler_context; + struct event_file_link *link; + unsigned long addr =3D bp->attr.bp_addr; + + trace_probe_for_each_link_rcu(link, &tw->tp) + wprobe_trace_handler(tw, addr, regs, link->file); +} + +static int __register_trace_wprobe(struct trace_wprobe *tw) +{ + struct perf_event_attr attr; + int i, ret; + + if (tw->bp_event) + return -EINVAL; + + for (i =3D 0; i < tw->tp.nr_args; i++) { + ret =3D traceprobe_update_arg(&tw->tp.args[i]); + if (ret) + return ret; + } + + hw_breakpoint_init(&attr); + attr.bp_addr =3D tw->addr; + attr.bp_len =3D tw->len; + attr.bp_type =3D tw->type; + + tw->bp_event =3D register_wide_hw_breakpoint(&attr, wprobe_perf_handler, = tw); + if (IS_ERR_PCPU(tw->bp_event)) { + int ret =3D PTR_ERR_PCPU(tw->bp_event); + + tw->bp_event =3D NULL; + return ret; + } + + return 0; +} + +static void __unregister_trace_wprobe(struct trace_wprobe *tw) +{ + if (tw->bp_event) { + unregister_wide_hw_breakpoint(tw->bp_event); + tw->bp_event =3D NULL; + } +} + +static void free_trace_wprobe(struct trace_wprobe *tw) +{ + if (tw) { + trace_probe_cleanup(&tw->tp); + kfree(tw->symbol); + kfree(tw); + } +} +DEFINE_FREE(free_trace_wprobe, struct trace_wprobe *, + if (!IS_ERR_OR_NULL(_T)) + free_trace_wprobe(_T)) + + +static struct trace_wprobe *alloc_trace_wprobe(const char *group, + const char *event, + const char *symbol, + int offset, + unsigned long addr, + int len, int type, int nargs) +{ + struct trace_wprobe *tw __free(free_trace_wprobe) =3D NULL; + int ret; + + tw =3D kzalloc_flex(*tw, tp.args, nargs); + if (!tw) + return ERR_PTR(-ENOMEM); + + if (symbol) { + tw->symbol =3D kstrdup(symbol, GFP_KERNEL); + if (!tw->symbol) + return ERR_PTR(-ENOMEM); + } + tw->offset =3D offset; + tw->addr =3D addr; + tw->len =3D len; + tw->type =3D type; + + ret =3D trace_probe_init(&tw->tp, event, group, false, nargs); + if (ret < 0) + return ERR_PTR(ret); + + dyn_event_init(&tw->devent, &trace_wprobe_ops); + return_ptr(tw); +} + +static struct trace_wprobe *find_trace_wprobe(const char *event, + const char *group) +{ + struct dyn_event *pos; + struct trace_wprobe *tw; + + for_each_trace_wprobe(tw, pos) + if (strcmp(trace_probe_name(&tw->tp), event) =3D=3D 0 && + strcmp(trace_probe_group_name(&tw->tp), group) =3D=3D 0) + return tw; + return NULL; +} + +static enum print_line_t +print_wprobe_event(struct trace_iterator *iter, int flags, + struct trace_event *event) +{ + struct wprobe_trace_entry_head *field; + struct trace_seq *s =3D &iter->seq; + struct trace_probe *tp; + + field =3D (struct wprobe_trace_entry_head *)iter->ent; + tp =3D trace_probe_primary_from_call( + container_of(event, struct trace_event_call, event)); + if (WARN_ON_ONCE(!tp)) + goto out; + + trace_seq_printf(s, "%s: (", trace_probe_name(tp)); + + if (!seq_print_ip_sym_offset(s, field->ip, flags)) + goto out; + + trace_seq_putc(s, ')'); + + if (trace_probe_print_args(s, tp->args, tp->nr_args, + (u8 *)&field[1], field) < 0) + goto out; + + trace_seq_putc(s, '\n'); +out: + return trace_handle_return(s); +} + +static int wprobe_event_define_fields(struct trace_event_call *event_call) +{ + int ret; + struct wprobe_trace_entry_head field; + struct trace_probe *tp; + + tp =3D trace_probe_primary_from_call(event_call); + if (WARN_ON_ONCE(!tp)) + return -ENOENT; + + DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0); + + return traceprobe_define_arg_fields(event_call, sizeof(field), tp); +} + +static struct trace_event_functions wprobe_funcs =3D { + .trace =3D print_wprobe_event +}; + +static struct trace_event_fields wprobe_fields_array[] =3D { + { .type =3D TRACE_FUNCTION_TYPE, + .define_fields =3D wprobe_event_define_fields }, + {} +}; + +static int wprobe_register(struct trace_event_call *event, + enum trace_reg type, void *data); + +static inline void init_trace_event_call(struct trace_wprobe *tw) +{ + struct trace_event_call *call =3D trace_probe_event_call(&tw->tp); + + call->event.funcs =3D &wprobe_funcs; + call->class->fields_array =3D wprobe_fields_array; + call->flags =3D TRACE_EVENT_FL_WPROBE; + call->class->reg =3D wprobe_register; +} + +static int register_wprobe_event(struct trace_wprobe *tw) +{ + init_trace_event_call(tw); + return trace_probe_register_event_call(&tw->tp); +} + +static int register_trace_wprobe_event(struct trace_wprobe *tw) +{ + struct trace_wprobe *old_tw; + int ret; + + guard(mutex)(&event_mutex); + + old_tw =3D find_trace_wprobe(trace_probe_name(&tw->tp), + trace_probe_group_name(&tw->tp)); + if (old_tw) { + /* + * Wprobe does not support sibling probes because the event + * trigger (set_wprobe/clear_wprobe) identifies the target + * wprobe by its event name. Having multiple wprobes sharing + * the same event name would make the target ambiguous. + */ + trace_probe_log_set_index(0); + trace_probe_log_err(0, WPROBE_NO_SIBLING); + return -EBUSY; + } + + ret =3D register_wprobe_event(tw); + if (ret) { + trace_probe_log_set_index(0); + if (ret =3D=3D -EEXIST) + trace_probe_log_err(0, EVENT_EXIST); + else if (ret !=3D -ENOMEM) + trace_probe_log_err(0, FAIL_REG_PROBE); + return ret; + } + + dyn_event_add(&tw->devent, trace_probe_event_call(&tw->tp)); + return 0; +} +static int unregister_wprobe_event(struct trace_wprobe *tw) +{ + return trace_probe_unregister_event_call(&tw->tp); +} + +static int unregister_trace_wprobe(struct trace_wprobe *tw) +{ + if (trace_probe_has_sibling(&tw->tp)) + goto unreg; + + if (trace_probe_is_enabled(&tw->tp)) + return -EBUSY; + + if (trace_event_dyn_busy(trace_probe_event_call(&tw->tp))) + return -EBUSY; + + if (unregister_wprobe_event(tw)) + return -EBUSY; + +unreg: + __unregister_trace_wprobe(tw); + dyn_event_remove(&tw->devent); + trace_probe_unlink(&tw->tp); + + return 0; +} + +static int enable_trace_wprobe(struct trace_event_call *call, + struct trace_event_file *file) +{ + struct trace_probe *tp; + struct trace_wprobe *tw; + bool enabled; + int ret =3D 0; + + tp =3D trace_probe_primary_from_call(call); + if (WARN_ON_ONCE(!tp)) + return -ENODEV; + enabled =3D trace_probe_is_enabled(tp); + + if (file) { + ret =3D trace_probe_add_file(tp, file); + if (ret) + return ret; + } else { + trace_probe_set_flag(tp, TP_FLAG_PROFILE); + } + + if (!enabled) { + list_for_each_entry(tw, trace_probe_probe_list(tp), tp.list) { + ret =3D __register_trace_wprobe(tw); + if (ret < 0) { + struct trace_wprobe *tmp; + + list_for_each_entry(tmp, trace_probe_probe_list(tp), tp.list) { + if (tmp =3D=3D tw) + break; + __unregister_trace_wprobe(tmp); + } + if (file) + trace_probe_remove_file(tp, file); + else + trace_probe_clear_flag(tp, TP_FLAG_PROFILE); + return ret; + } + } + } + + return 0; +} + +static int disable_trace_wprobe(struct trace_event_call *call, + struct trace_event_file *file) +{ + struct trace_wprobe *tw; + struct trace_probe *tp; + + tp =3D trace_probe_primary_from_call(call); + if (WARN_ON_ONCE(!tp)) + return -ENODEV; + + if (file) { + if (!trace_probe_get_file_link(tp, file)) + return -ENOENT; + if (!trace_probe_has_single_file(tp)) + goto out; + trace_probe_clear_flag(tp, TP_FLAG_TRACE); + } else { + trace_probe_clear_flag(tp, TP_FLAG_PROFILE); + } + + if (!trace_probe_is_enabled(tp)) { + list_for_each_entry(tw, trace_probe_probe_list(tp), tp.list) { + __unregister_trace_wprobe(tw); + } + } + +out: + if (file) + trace_probe_remove_file(tp, file); + + return 0; +} + +static int wprobe_register(struct trace_event_call *event, + enum trace_reg type, void *data) +{ + struct trace_event_file *file =3D data; + + switch (type) { + case TRACE_REG_REGISTER: + return enable_trace_wprobe(event, file); + case TRACE_REG_UNREGISTER: + return disable_trace_wprobe(event, file); + +#ifdef CONFIG_PERF_EVENTS + case TRACE_REG_PERF_REGISTER: + case TRACE_REG_PERF_UNREGISTER: + case TRACE_REG_PERF_OPEN: + case TRACE_REG_PERF_CLOSE: + case TRACE_REG_PERF_ADD: + case TRACE_REG_PERF_DEL: + return -EOPNOTSUPP; +#endif + } + return 0; +} + +static bool trace_wprobe_is_valid_addr(unsigned long addr, int len) +{ + if (addr < TASK_SIZE) + return false; + + if (addr & (len - 1)) + return false; + + return true; +} + +static int parse_address_spec(const char *spec, unsigned long *addr, int *= type, + int *len, char **symbol, int *offset) +{ + char *_spec __free(kfree) =3D NULL; + int _len =3D HW_BREAKPOINT_LEN_4; + int _type =3D HW_BREAKPOINT_RW; + unsigned long _addr =3D 0; + int _offset =3D 0; + char *at, *col; + + _spec =3D kstrdup(spec, GFP_KERNEL); + if (!_spec) + return -ENOMEM; + + at =3D strchr(_spec, '@'); + col =3D strchr(_spec, ':'); + + if (!at) { + trace_probe_log_err(0, BAD_ACCESS_FMT); + return -EINVAL; + } + + if (at !=3D _spec) { + *at =3D '\0'; + + if (strcmp(_spec, "r") =3D=3D 0) + _type =3D HW_BREAKPOINT_R; + else if (strcmp(_spec, "w") =3D=3D 0) + _type =3D HW_BREAKPOINT_W; + else if (strcmp(_spec, "rw") =3D=3D 0) + _type =3D HW_BREAKPOINT_RW; + else { + trace_probe_log_err(0, BAD_ACCESS_TYPE); + return -EINVAL; + } + } + + if (col) { + *col =3D '\0'; + if (kstrtoint(col + 1, 0, &_len)) { + trace_probe_log_err(col + 1 - _spec, BAD_ACCESS_LEN); + return -EINVAL; + } + + switch (_len) { + case 1: + _len =3D HW_BREAKPOINT_LEN_1; + break; + case 2: + _len =3D HW_BREAKPOINT_LEN_2; + break; + case 4: + _len =3D HW_BREAKPOINT_LEN_4; + break; + case 8: + _len =3D HW_BREAKPOINT_LEN_8; + break; + default: + trace_probe_log_err(col + 1 - _spec, BAD_ACCESS_LEN); + return -EINVAL; + } + } + + if (kstrtoul(at + 1, 0, &_addr) !=3D 0) { + char *off_str =3D strpbrk(at + 1, "+-"); + + if (off_str) { + if (kstrtoint(off_str, 0, &_offset) !=3D 0) { + trace_probe_log_err(off_str - _spec, BAD_PROBE_ADDR); + return -EINVAL; + } + *off_str =3D '\0'; + } + _addr =3D kallsyms_lookup_name(at + 1); + if (!_addr) { + trace_probe_log_err(at + 1 - _spec, BAD_ACCESS_ADDR); + return -ENOENT; + } + _addr +=3D _offset; + *symbol =3D kstrdup(at + 1, GFP_KERNEL); + if (!*symbol) + return -ENOMEM; + } + + if (!trace_wprobe_is_valid_addr(_addr, _len)) { + trace_probe_log_err(at + 1 - _spec, BAD_ACCESS_ADDR); + return -EINVAL; + } + + *addr =3D _addr; + *offset =3D _offset; + *type =3D _type; + *len =3D _len; + return 0; +} + +static int __trace_wprobe_create(int argc, const char *argv[]) +{ + /* + * Argument syntax: + * w[:[GRP/][EVENT]] SPEC + * + * SPEC: + * [r|w|rw]@[ADDR|SYMBOL[+OFFS]][:LEN] + */ + struct traceprobe_parse_context *ctx __free(traceprobe_parse_context) =3D= NULL; + struct trace_wprobe *tw __free(free_trace_wprobe) =3D NULL; + const char *event =3D NULL, *group =3D WPROBE_EVENT_SYSTEM; + const char *tplog __free(trace_probe_log_clear) =3D NULL; + char *symbol __free(kfree) =3D NULL; + char *gbuf __free(kfree) =3D NULL; + char *ebuf __free(kfree) =3D NULL; + unsigned long addr; + int len, type, offset, i; + int ret; + + if (argv[0][0] !=3D 'w') + return -ECANCELED; + + tplog =3D trace_probe_log_init("wprobe", argc, argv); + + if (argc < 2) { + trace_probe_log_set_index(0); + trace_probe_log_err(0, NO_ARG_BODY); + return -EINVAL; + } + + if (argv[0][1] !=3D '\0') { + if (argv[0][1] !=3D ':') { + trace_probe_log_set_index(0); + trace_probe_log_err(1, WPROBE_NO_MAXACT); + return -EINVAL; + } + event =3D &argv[0][2]; + } + + trace_probe_log_set_index(1); + ret =3D parse_address_spec(argv[1], &addr, &type, &len, &symbol, &offset); + if (ret < 0) + return ret; + + trace_probe_log_set_index(0); + if (event) { + gbuf =3D kmalloc(MAX_EVENT_NAME_LEN, GFP_KERNEL); + if (!gbuf) + return -ENOMEM; + ret =3D traceprobe_parse_event_name(&event, &group, gbuf, + event - argv[0]); + if (ret) + return ret; + } + + if (!event) { + /* Make a new event name */ + ebuf =3D kmalloc(MAX_EVENT_NAME_LEN, GFP_KERNEL); + if (!ebuf) + return -ENOMEM; + if (symbol) + snprintf(ebuf, MAX_EVENT_NAME_LEN, "%s", symbol); + else + snprintf(ebuf, MAX_EVENT_NAME_LEN, "w_0x%lx", addr); + sanitize_event_name(ebuf); + event =3D ebuf; + } + + argc -=3D 2; argv +=3D 2; + if (argc > MAX_TRACE_ARGS) { + trace_probe_log_set_index(2); + trace_probe_log_err(0, TOO_MANY_ARGS); + return -E2BIG; + } + tw =3D alloc_trace_wprobe(group, event, symbol, offset, addr, len, type, = argc); + if (IS_ERR(tw)) + return PTR_ERR(tw); + + ctx =3D kzalloc_obj(*ctx); + if (!ctx) + return -ENOMEM; + + ctx->flags =3D TPARG_FL_KERNEL | TPARG_FL_WPROBE; + + /* parse arguments */ + for (i =3D 0; i < argc; i++) { + trace_probe_log_set_index(i + 2); + ctx->offset =3D 0; + ret =3D traceprobe_parse_probe_arg(&tw->tp, i, argv[i], ctx); + if (ret) + return ret; /* This can be -ENOMEM */ + } + + ret =3D traceprobe_set_print_fmt(&tw->tp, PROBE_PRINT_NORMAL); + if (ret < 0) + return ret; + + ret =3D register_trace_wprobe_event(tw); + if (!ret) + tw =3D NULL; /* To avoid free */ + + return ret; +} + +static int trace_wprobe_create(const char *raw_command) +{ + return trace_probe_create(raw_command, __trace_wprobe_create); +} + +static int trace_wprobe_release(struct dyn_event *ev) +{ + struct trace_wprobe *tw =3D to_trace_wprobe(ev); + int ret =3D unregister_trace_wprobe(tw); + + if (!ret) + free_trace_wprobe(tw); + return ret; +} + +static int trace_wprobe_show(struct seq_file *m, struct dyn_event *ev) +{ + struct trace_wprobe *tw =3D to_trace_wprobe(ev); + const char *type_str; + int i, len; + + seq_printf(m, "w:%s/%s", trace_probe_group_name(&tw->tp), + trace_probe_name(&tw->tp)); + + if (tw->type =3D=3D HW_BREAKPOINT_R) + type_str =3D "r"; + else if (tw->type =3D=3D HW_BREAKPOINT_W) + type_str =3D "w"; + else + type_str =3D "rw"; + + if (tw->len =3D=3D HW_BREAKPOINT_LEN_1) + len =3D 1; + else if (tw->len =3D=3D HW_BREAKPOINT_LEN_2) + len =3D 2; + else if (tw->len =3D=3D HW_BREAKPOINT_LEN_4) + len =3D 4; + else + len =3D 8; + + if (tw->symbol) { + if (tw->offset) + seq_printf(m, " %s@%s%+d:%d", type_str, tw->symbol, + tw->offset, len); + else + seq_printf(m, " %s@%s:%d", type_str, tw->symbol, len); + } else { + seq_printf(m, " %s@0x%lx:%d", type_str, tw->addr, len); + } + + for (i =3D 0; i < tw->tp.nr_args; i++) + seq_printf(m, " %s=3D%s", tw->tp.args[i].name, tw->tp.args[i].comm); + seq_putc(m, '\n'); + + return 0; +} + +static __init int init_wprobe_trace(void) +{ + return dyn_event_register(&trace_wprobe_ops); +} +fs_initcall(init_wprobe_trace); + From nobody Sat Sep 26 01:04:32 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 43AE03ED3BA; Mon, 7 Sep 2026 03:47:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788752853; cv=none; b=fylXC1IB3xKJ3HYHRmr8K15IjLgOXdw/Zg5X0NpVJpEjrxqE89PBmKH3ZH3TywEIYFGFvG1hLmy+HFnJoxq2kcP8QHf8+q/TvN2Que+Cfb7dslM9DnNMrZ0aEjXbPsfT9GH++T6GRxswyREhlHKfkaLDvP7UgGCIZ14cHI6pZNQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788752853; c=relaxed/simple; bh=vFJelAs6RkUEfep9+zWnllKBieB5TLqkKRYzQduYJEE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=YQICyDyZVJr+MaLBuVRQ+ieSEL+/CKEfIXYvyhoEvTVgBP51u9/zZjJFC0r5nUpDoSypFDyXPs52BkN7g479GEdukrbs/a+UaOKz25DYVOsTIfhLKFrxxzJAYj3HgM3LWO0NFIrefP4XfhU+kH1nvot9M3LutPzsbSvxbIQEe/8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=IiDJcbUN; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="IiDJcbUN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5EF9D1F00A3A; Mon, 7 Sep 2026 03:47:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788752852; bh=DVcGk6Bv8eEUx8YBEhCPRwunKrlLmLX0y57ylhq+Cto=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=IiDJcbUN8ZCoEUyHVYoPfXwggf9NjO8/1BhRQX3nTCDqz0Uv0Y9hjkHS8kB/tLcNo HaeyyHLSKaajffzSxTdy2d0Ljgjs7vHtIgFOvNDrwOaJosqHvoledOmshFBP514/O+ EpzTEi/ok67euDNXE/OjHlrhBmKWHcyWq3K6DhCxm+JfXFdEvpTwNfZUbysuWK/VBX N3E4oQEpBZsITos+mFAPSjlmYFO/GfJLNpSS2ky74C8hqJ+n/P6mxQTDRHJI5hRkp3 TttpI4S8ma4vRcifDC9oRo26GhhWNx7Tuec6U9yC5ncWd+bKEFMDghE7/7ud44cot6 C1REtuHknIOzg== From: "Masami Hiramatsu (Google)" To: Steven Rostedt , Peter Zijlstra , Ingo Molnar , x86@kernel.org Cc: Jinchao Wang , Mathieu Desnoyers , Masami Hiramatsu , Thomas Gleixner , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Alexander Shishkin , Ian Rogers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: [PATCH v15 06/12] x86: hw_breakpoint: Add a kconfig to clarify when a breakpoint fires Date: Mon, 7 Sep 2026 12:47:26 +0900 Message-ID: <178875284616.93794.3461261498789544150.stgit@devnote2> X-Mailer: git-send-email 2.43.0 In-Reply-To: <178875277830.93794.14247844688761142429.stgit@devnote2> References: <178875277830.93794.14247844688761142429.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Masami Hiramatsu (Google) Add CONFIG_HAVE_POST_BREAKPOINT_HOOK which indicates the hw_breakpoint on that architecture fires after the target memory has been modified. This is currently x86 only behavior. Signed-off-by: Masami Hiramatsu (Google) Reviewed-by: Jinchao Wang --- Changes in v11: - Move select to alphabetically sorted place. --- arch/Kconfig | 10 ++++++++++ arch/x86/Kconfig | 1 + kernel/trace/Kconfig | 1 + 3 files changed, 12 insertions(+) diff --git a/arch/Kconfig b/arch/Kconfig index d021bc31ef14..5292bd05d5d4 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -474,6 +474,16 @@ config HAVE_MIXED_BREAKPOINTS_REGS Select this option if your arch implements breakpoints under the latter fashion. =20 +config HAVE_POST_BREAKPOINT_HOOK + bool + depends on HAVE_HW_BREAKPOINT + help + Depending on the arch implementation of hardware breakpoints, + some of them provide breakpoint hook after the target memory + is modified. + Select this option if your arch implements breakpoints overflow + handler hooks after the target memory is modified. + config HAVE_MODIFY_LOCAL_HW_BREAKPOINT_ADDR bool depends on HAVE_HW_BREAKPOINT diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 38e29e465022..e4eaf0b607d3 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -289,6 +289,7 @@ config X86 select MMU_GATHER_RCU_TABLE_FREE select MMU_GATHER_MERGE_VMAS select HAVE_POSIX_CPU_TIMERS_TASK_WORK + select HAVE_POST_BREAKPOINT_HOOK select HAVE_REGS_AND_STACK_ACCESS_API select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION select HAVE_FUNCTION_ARG_ACCESS_API diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index b58c2565024f..d9b6fa5c35d9 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -866,6 +866,7 @@ config WPROBE_EVENTS bool "Enable wprobe-based dynamic events" depends on TRACING depends on HAVE_HW_BREAKPOINT + depends on HAVE_POST_BREAKPOINT_HOOK select PROBE_EVENTS select DYNAMIC_EVENTS help From nobody Sat Sep 26 01:04:32 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 504E63EF0BD; Mon, 7 Sep 2026 03:47:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788752864; cv=none; b=jyMQa1MnX+PXoSVOpWVkDwNeMaU1oIltdCG/gpPtYaZfx3WAc9EjkEUQWOBvhQtmwEOvfEYcIFEO/RWACwQ4vVGN93nJR2xubQAyABOEYcwSx8wxOwDyDfCWMv/eD483UOyc1aycBQrIxcZHJV2ZRuiVk7fVJHwsA4oT/OJodkw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788752864; c=relaxed/simple; bh=7WwAsjXAm72C3N+aWoYKuzBUFcwI27R/LA/82emnZ6M=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=jW/Ep2bsAJA3aewLvNcQxkEiKLc6kvjVXXjM3GSxMV4iKyWLhuK5fso5AmPCqdhsFsIBrfGAQHrBAtfGlNwbWcXXm3GJF3GDkcNp0/B2DaPAQ5FOzPw8+50+RUhwak0ZqXM722gMtEPcnnQdil9009BlYx7356qN7lJA4I0wfvI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=n6BKsBis; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="n6BKsBis" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 869781F00A3A; Mon, 7 Sep 2026 03:47:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788752863; bh=lcnl1Kiyu2/Ws5GS/yrGcGPFrteWWVQg5IT2n1yE1q0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=n6BKsBisbhdDWolCiv5TCiUdnRYIzFvalc+0u986T4NmKRJ5iddgpUeLCMTsoqXTx wg2s3CsO+5FI19KdLYIWW/B4lstUsX3SbpEawIJV/QKg4yHUbp5Lz8rjmj0sBD5D4P tKHfSGSkRjd4qnGAzhs1JTc3/pvUJv5pDlHLrmxxvE2VTYgsu8KSRRQa1aTgHPvZMO DFqEr8VkQFGCSaoIFmDKIQMkABT21isEJT0hNVX6vtLIG0kF20V3qGa63ZETUGm9Lf trbVuRYhuRnxZNe8GqDUk3ZQ983UUvjUpYh8Dd2wCXP1CDsmbpL/LoumqRerm1RslS YZ1fasdm2yQsw== From: "Masami Hiramatsu (Google)" To: Steven Rostedt , Peter Zijlstra , Ingo Molnar , x86@kernel.org Cc: Jinchao Wang , Mathieu Desnoyers , Masami Hiramatsu , Thomas Gleixner , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Alexander Shishkin , Ian Rogers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: [PATCH v15 07/12] selftests: tracing: Add a basic testcase for wprobe Date: Mon, 7 Sep 2026 12:47:37 +0900 Message-ID: <178875285732.93794.2953704844412327111.stgit@devnote2> X-Mailer: git-send-email 2.43.0 In-Reply-To: <178875277830.93794.14247844688761142429.stgit@devnote2> References: <178875277830.93794.14247844688761142429.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Masami Hiramatsu (Google) Add 'add_remove_wprobe.tc' testcase for testing wprobe event that tests adding and removing operations of the wprobe event. Signed-off-by: Masami Hiramatsu (Google) --- Changes in v9: - Fix command check logic to prevent early exit under 'set -e' (errexit) when grep or test fails. - Simplify enable/disable status checks by removing cat pipes. Changes in v8: - Fixed silently test failure path. --- tools/testing/selftests/ftrace/config | 1=20 .../ftrace/test.d/dynevent/add_remove_wprobe.tc | 63 ++++++++++++++++= ++++ 2 files changed, 64 insertions(+) create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/add_remo= ve_wprobe.tc diff --git a/tools/testing/selftests/ftrace/config b/tools/testing/selftest= s/ftrace/config index 544de0db5f58..d2f503722020 100644 --- a/tools/testing/selftests/ftrace/config +++ b/tools/testing/selftests/ftrace/config @@ -27,3 +27,4 @@ CONFIG_STACK_TRACER=3Dy CONFIG_TRACER_SNAPSHOT=3Dy CONFIG_UPROBES=3Dy CONFIG_UPROBE_EVENTS=3Dy +CONFIG_WPROBE_EVENTS=3Dy diff --git a/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_wpro= be.tc b/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_wprobe.tc new file mode 100644 index 000000000000..647c37d5e4c8 --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_wprobe.tc @@ -0,0 +1,63 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# description: Generic dynamic event - add/remove wprobe events +# requires: dynamic_events "w[:[/][]] [r|w|rw]@[:= ]":README + +echo 0 > events/enable +echo > dynamic_events + +# Use jiffies as a variable that is frequently written to. +TARGET=3Djiffies + +echo "w:my_wprobe w@$TARGET" >> dynamic_events + +if ! grep -q my_wprobe dynamic_events; then + echo "Failed to create wprobe event" + exit_fail +fi + +if [ ! -d events/wprobes/my_wprobe ]; then + echo "Failed to create wprobe event directory" + exit_fail +fi + +echo 1 > events/wprobes/my_wprobe/enable + +# Check if the event is enabled +if ! grep -q 1 events/wprobes/my_wprobe/enable; then + echo "Failed to enable wprobe event" + exit_fail +fi + +# Let some time pass to trigger the breakpoint +sleep 1 + +# Check if we got any trace output +if ! grep -q my_wprobe trace; then + echo "wprobe event was not triggered" + exit_fail +fi + +echo 0 > events/wprobes/my_wprobe/enable + +# Check if the event is disabled +if ! grep -q 0 events/wprobes/my_wprobe/enable; then + echo "Failed to disable wprobe event" + exit_fail +fi + +echo "-:my_wprobe" >> dynamic_events + +if grep -q my_wprobe dynamic_events; then + echo "Failed to remove wprobe event" + exit_fail +fi + +if [ -d events/wprobes/my_wprobe ]; then + echo "Failed to remove wprobe event directory" + exit_fail +fi + +clear_trace + +exit 0 From nobody Sat Sep 26 01:04:32 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 6E7AD3EFD27; Mon, 7 Sep 2026 03:47:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788752875; cv=none; b=M4atfqGvWpZN6TGpOhdfZHLbnnfU8mq2t4d8VvKJWqTBRUPRSa7Ff4M93CRutDrdA7BozwlnLK0GWuKZkGQrvcR2XwignCTS2D2Bmh2AR3Pmty2fDqOmPWzURWz0YYi1LFQ3+F2QEMPLeKcVN6Gc5EAPnBkPYNKRTpaMt7eMRNk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788752875; c=relaxed/simple; bh=w/fxHVNtA+8suk/aVIjfFU697JVRJgCgDhdycK2gkzs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=dgAL/Svf9jj7gz7wfjra9BcX2oPV4S+XrTuDdOgMnSUArMaubQvZtPCvBLJ/FbeYq+9LEcMAfc2WcQySk9/hWb7CFAYfFj+r4XrW2xaPuqy8Oegbm5Q7RrhyI5Z6eTzKjyhVhjh5NuP8iGxhDsVIu/+Gg3aPcPQXlmLkTJTAizo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=M1Z6lxPb; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="M1Z6lxPb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7C11C1F00A3A; Mon, 7 Sep 2026 03:47:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788752874; bh=o0qMmOfhKF4hfQTENoYGXCxXEOkOcEeucQ2rUqmquDU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=M1Z6lxPbDckbjy30jdFkBwxaK/j95DWpNMNm7Dbj2BbbdqGBI3nXVrLqlm0crrKq8 gwjVd5wGUY1uLARxvozfoxysQMCXImff/TW1Trm2S4x7Si4Uj4fThEctUhEdPNq2dh VFVIf9Rm9VMCvwt8LIr7BwspF6ViFtEx3Kjl4cXIihfQtOwmBBQMlTWLZIgeIMz40h ZEr7K+L7iUaw82eHunYb14ehWcv0a9DP/4TB9xdqmfqBiyixI08fTEj1X+hWw6AsM4 J1ZK4j7B1KbAeRveeUwEKzgQu4+bkla3P2pXMFi9iC4+Wy5bjLvbrdHcprXnVuQXdP pE+IyXaXVWzoA== From: "Masami Hiramatsu (Google)" To: Steven Rostedt , Peter Zijlstra , Ingo Molnar , x86@kernel.org Cc: Jinchao Wang , Mathieu Desnoyers , Masami Hiramatsu , Thomas Gleixner , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Alexander Shishkin , Ian Rogers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: [PATCH v15 08/12] selftests: tracing: Add syntax testcase for wprobe Date: Mon, 7 Sep 2026 12:47:48 +0900 Message-ID: <178875286830.93794.14966404625232529162.stgit@devnote2> X-Mailer: git-send-email 2.43.0 In-Reply-To: <178875277830.93794.14247844688761142429.stgit@devnote2> References: <178875277830.93794.14247844688761142429.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Masami Hiramatsu (Google) Add "wprobe_syntax_errors.tc" testcase for testing syntax errors of the watch probe events. Signed-off-by: Masami Hiramatsu (Google) --- Changes in v14: - Update comment for invalid offset syntax check to BAD_PROBE_ADDR. - Add testcase for invalid address 0 error check (BAD_ACCESS_ADDR). Changes in v12: - Add NO_ARG_BODY error case. Changes in v11: - Add WPROBE_NO_MAXACT syntax error case. --- .../test.d/dynevent/wprobes_syntax_errors.tc | 23 ++++++++++++++++= ++++ 1 file changed, 23 insertions(+) create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/wprobes_= syntax_errors.tc diff --git a/tools/testing/selftests/ftrace/test.d/dynevent/wprobes_syntax_= errors.tc b/tools/testing/selftests/ftrace/test.d/dynevent/wprobes_syntax_e= rrors.tc new file mode 100644 index 000000000000..e0df58fe7aa3 --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/dynevent/wprobes_syntax_errors.= tc @@ -0,0 +1,23 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# description: Watch probe event parser error log check +# requires: dynamic_events "w[:[/][]] [r|w|rw]@[:= ]":README + +check_error() { # command-with-error-pos-by-^ + ftrace_errlog_check 'wprobe' "$1" 'dynamic_events' +} + +check_error '^w' # NO_ARG_BODY +check_error 'w^10 w@jiffies' # WPROBE_NO_MAXACT +check_error 'w ^symbol' # BAD_ACCESS_FMT +check_error 'w ^a@symbol' # BAD_ACCESS_TYPE +check_error 'w w@^symbol' # BAD_ACCESS_ADDR +check_error 'w w@^0:4' # BAD_ACCESS_ADDR +check_error 'w w@jiffies^+offset' # BAD_PROBE_ADDR +check_error 'w w@jiffies:^100' # BAD_ACCESS_LEN +check_error 'w w@jiffies ^$arg1' # BAD_VAR +check_error 'w w@jiffies ^$retval' # BAD_VAR +check_error 'w w@jiffies ^$stack' # BAD_VAR +check_error 'w w@jiffies ^%ax' # BAD_VAR + +exit 0 From nobody Sat Sep 26 01:04:32 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 C74AD3ED3BA; Mon, 7 Sep 2026 03:48:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788752888; cv=none; b=d89570Gc4JErMkNESMr/izdYWYTG/J2hddjC7gBCFExnXBwBXFmZlGpZfyoYUwrsQ3DNzlI13jr/w7i0u+9bW7xpzP5sh6qQVFcVM2AsEztXg1/40sbt4SDkEtC+CMFn1OxWXsDrIxVBppTF25TrOCIfc54+50J5PsPAyil0N+k= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788752888; c=relaxed/simple; bh=3AbUjjnQs1C5bwmhI9tbnLF8WNCOoG9AdrpU1AIYWqY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=a2z5aQuX2fvC5nA95llzMmZPT3BMm9B775RAHRF8P0hDhQqJaU6CqMw8EGCe0DQm7+POyNvLwTxT4oA/EgCI0PGsW5M1y7LYIN6TGqK62Ep9WLzccPeyUrqwm4wJNjUDNnKxxvp5AdGnbwMzo3VSYohO5VsfWJ+DnbTpM3b6oWk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=AHZxy4lP; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="AHZxy4lP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BC7E11F00A3A; Mon, 7 Sep 2026 03:48:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788752885; bh=TFXOlHfwh9H8ULU948+ck91vvS8QoXCiKQGYI8w5BAk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=AHZxy4lPhoNIeb57xMag6RLAIbikRIc8RveEe3RtQogINE7ZnQ2h9NVNSWsgEa9wm 7G6f/s2dSS4tJjrZBG9Xz1PzixLF0Y2Qc5XsWYsrreaRb9cg6/BAONgs6pbMfO9C4u AIWWz9p78GQBeEq6px78ZcC8p5tFpnVLpdK9SSZxkeW96a9R65FLsX3ZDdcKtwC+Yq zQEWLp85NvsYDm7mNBRS+NJV21SEkA9ua41LmR09YTDCGQUaHjU/pk3vIRxYijJ+Tz H3irYGJxWI9bC3sNX+rgzcSpC7Y3SlpJ6CXa8wdmMyIxgyvU4G3dq802nBpggZ/6NP H8hKQUwJ099nw== From: "Masami Hiramatsu (Google)" To: Steven Rostedt , Peter Zijlstra , Ingo Molnar , x86@kernel.org Cc: Jinchao Wang , Mathieu Desnoyers , Masami Hiramatsu , Thomas Gleixner , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Alexander Shishkin , Ian Rogers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: [PATCH v15 09/12] tracing/wprobe: Add set_wprobe and clear_wprobe event triggers Date: Mon, 7 Sep 2026 12:47:59 +0900 Message-ID: <178875287944.93794.8914114071047199197.stgit@devnote2> X-Mailer: git-send-email 2.43.0 In-Reply-To: <178875277830.93794.14247844688761142429.stgit@devnote2> References: <178875277830.93794.14247844688761142429.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Masami Hiramatsu (Google) Add set_wprobe and clear_wprobe event triggers to dynamically attach and detach hardware breakpoint address monitoring based on event field contents. Link: https://lore.kernel.org/all/59637b96946653393a7ad3c7de094094796b39c2.= 1785067572.git.wangjinchao600@gmail.com/ Assisted-by: Antigravity:gemini-3.8-flash Signed-off-by: Masami Hiramatsu (Google) --- Changes in v15: - Use trace_wprobe_is_valid_addr() in wprobe_trigger() to validate address and natural alignment for wprobe length. - Record SMP local update failures in tw->missed counter. - Expose missed event count as a trailing comment in trigger file. - Add set_wprobe and clear_wprobe triggers to readme_msg in trace.c. - Fix line length exceeding 100 columns in wprobe_trigger_log_err macro. - Initialize irq_work and work structs immediately after allocation in alloc_trace_wprobe() and check tw->work.func in free_trace_wprobe() to prevent WARN_ON(!work->func) on early allocation failure. Changes in v14: - Allow '-1' as a dummy address in parse_address_spec() to set initial address to WPROBE_DEFAULT_CLEAR_ADDRESS for trigger-only wprobes. - In trace_wprobe_show(), format WPROBE_DEFAULT_CLEAR_ADDRESS as '-1'. - Update documentation and examples to use '-1' instead of '0'. - Skip field parsing in clear_wprobe if parameter is a count keyword. - Set tw->addr to WPROBE_DEFAULT_CLEAR_ADDRESS before soft-enabling event and roll back on failure. - Fix memory and refcount leak of trigger_data/wprobe_data on error path. Changes in v13: - Align WPROBE_DEFAULT_CLEAR_ADDRESS to 8 bytes using dedicated u64. - Remove manual count decrement to rely on core event_trigger_count(). - Parse optional FIELD argument in clear_wprobe command. - Fix trigger reference count leak and error cleanup in command parsing. - Update document to add [:COUNT] to trigger syntax and fix adjust forms. - Add notes about the exclusive trigger setting behavior. - Remove unused dyn_event_ops_mutex. Changes in v12: - Decrement trigger data->count only when watchpoint state is actually changed. - Remove dyn_event_ops_mutex to fix lockdep circular dependency deadlock. - Add event_trigger_init() call to prevent premature freeing of trigger_da= ta. --- Documentation/trace/wprobetrace.rst | 107 ++++++ include/linux/trace_events.h | 1=20 kernel/trace/Kconfig | 10 + kernel/trace/trace.c | 4=20 kernel/trace/trace.h | 1=20 kernel/trace/trace_events_trigger.c | 2=20 kernel/trace/trace_probe.c | 2=20 kernel/trace/trace_probe.h | 9 - kernel/trace/trace_wprobe.c | 609 +++++++++++++++++++++++++++++++= ++++ 9 files changed, 742 insertions(+), 3 deletions(-) diff --git a/Documentation/trace/wprobetrace.rst b/Documentation/trace/wpro= betrace.rst index 31cc68b464e9..df8985283312 100644 --- a/Documentation/trace/wprobetrace.rst +++ b/Documentation/trace/wprobetrace.rst @@ -76,3 +76,110 @@ Wprobe event does not disable itself even if the module= is unloaded. For example, if you add a wprobe event on a module variable, and then unload the module, the wprobe event will still be enabled. This is for watching the address is used unexpectedly after the module is unloaded. + +Combination with trigger action +------------------------------- +The event trigger action can extend the utilization of this wprobe. + +- set_wprobe:WPEVENT:FIELD[+|-ADJUST][:COUNT] +- clear_wprobe:WPEVENT[:FIELD[+|-ADJUST][:COUNT]] + +Set these triggers to the target event, then the WPROBE event will be +setup to trace the memory access at FIELD[+|-ADJUST] address. +When clear_wprobe is hit, if FIELD is NOT specified, the WPEVENT is +forcibly cleared. If FIELD[+|-ADJUST] is set, it clears WPEVENT only +if its watching address is the same as the FIELD[+|-ADJUST] value. +If COUNT is specified, it will set/clear WPEVENT only if it hits COUNT +times. + +Notes: +- set_wprobe only works on the wprobe which is NOT set a valid address yet, + and it must be enabled after the trigger is set. +- clear_wprobe only works on the wprobe which is set a valid address, and = it + will be soft-disabled after the trigger is cleared. +- Therefore, if a trigger sets/clears a wprobe, other/same trigger events + will not work (on the same event) while the wprobe is set. + +The set_wprobe trigger does not change the type and length, these +must be set when creating a new wprobe. + +The WPROBE event must be disabled when setting the new trigger +and it will be busy afterwards. Recommended usage is to add a new +wprobe at invalid dummy address (-1) and keep disabled. + +Wprobe triggers only support target addresses in kernel memory. If a +set_wprobe trigger evaluates to a user-space memory address or NULL +pointer, the trigger action ignores the update and skips setting the +watchpoint. + +Wprobe triggers are not supported on kprobe_events, because kprobes +themselves can use software breakpoints which conflicts with wprobe +operation. + + +For example, trace the first 8 bytes of the dentry data structure passed +to do_truncate() until it is deleted by dentry_kill(). +(Note: all tracefs setup uses '>>' so that it does not kick do_truncate()) +:: + + # echo 'w:watch rw@-1:8 address=3D$addr value=3D+0($addr)' >> dynamic_ev= ents + # echo 'f:truncate do_truncate dentry=3D$arg2' >> dynamic_events + # echo 'set_wprobe:watch:dentry' >> events/fprobes/truncate/trigger + # echo 'f:dentry_kill dentry_kill dentry=3D$arg1' >> dynamic_events + # echo 'clear_wprobe:watch:dentry' >> events/fprobes/dentry_kill/trigger + # echo 1 >> events/fprobes/truncate/enable + # echo 1 >> events/fprobes/dentry_kill/enable + + # echo aaa > /tmp/hoge + # echo bbb > /tmp/hoge + # echo ccc > /tmp/hoge + # rm /tmp/hoge + +Then, the trace data will show:: + + # tracer: nop + # + # entries-in-buffer/entries-written: 32/32 #P:8 + # + # _-----=3D> irqs-off/BH-disabled + # / _----=3D> need-resched + # | / _---=3D> hardirq/softirq + # || / _--=3D> preempt-depth + # ||| / _-=3D> migrate-disable + # |||| / delay + # TASK-PID CPU# ||||| TIMESTAMP FUNCTION + # | | | ||||| | | + sh-107 [004] ...1. 9.990418: dentry_kill: (dentry_k= ill+0x0/0x2c0) dentry=3D0xffff888004ad6618 + sh-107 [004] ...1. 9.990914: dentry_kill: (dentry_k= ill+0x0/0x2c0) dentry=3D0xffff888004b3de78 + sh-107 [004] ...1. 9.993175: dentry_kill: (dentry_k= ill+0x0/0x2c0) dentry=3D0xffff8880049ddd40 + sh-107 [004] ..... 9.995198: truncate: (do_truncate= +0x4/0x120) dentry=3D0xffff8880048083a8 + sh-107 [004] ...1. 9.995389: dentry_kill: (dentry_k= ill+0x0/0x2c0) dentry=3D0xffff8880049db998 + sh-107 [004] ..Zff 9.997503: watch: (lookup_fast+0x= aa/0x150) address=3D0xffff8880048083a8 value=3D0x8200080 + sh-107 [004] ..Zff 9.997509: watch: (path_openat+0x= 211/0xda0) address=3D0xffff8880048083a8 value=3D0x8200080 + sh-107 [004] ..Zff 9.997514: watch: (path_openat+0x= a56/0xda0) address=3D0xffff8880048083a8 value=3D0x8200080 + sh-107 [004] ..Zff 9.997518: watch: (path_openat+0x= ae2/0xda0) address=3D0xffff8880048083a8 value=3D0x8200080 + sh-107 [004] ..... 9.997521: truncate: (do_truncate= +0x4/0x120) dentry=3D0xffff8880048083a8 + sh-107 [004] ...1. 9.997582: dentry_kill: (dentry_k= ill+0x0/0x2c0) dentry=3D0xffff888004808270 + sh-107 [004] ...1. 9.999365: dentry_kill: (dentry_k= ill+0x0/0x2c0) dentry=3D0xffff8880049db728 + sh-107 [004] ...1. 9.999388: dentry_kill: (dentry_k= ill+0x0/0x2c0) dentry=3D0xffff888004b1c000 + rm-113 [005] ..Zff 10.000965: watch: (lookup_fast+0x= aa/0x150) address=3D0xffff8880048083a8 value=3D0x8200080 + rm-113 [005] ..Zff 10.000971: watch: (path_lookupat+= 0x97/0x1e0) address=3D0xffff8880048083a8 value=3D0x8200080 + rm-113 [005] ..Zff 10.000984: watch: (lookup_fast+0x= aa/0x150) address=3D0xffff8880048083a8 value=3D0x8200080 + rm-113 [005] ..Zff 10.000988: watch: (path_lookupat+= 0x97/0x1e0) address=3D0xffff8880048083a8 value=3D0x8200080 + rm-113 [005] ..Zff 10.001010: watch: (lookup_one_qst= r_excl+0x28/0x140) address=3D0xffff8880048083a8 value=3D0x8200080 + rm-113 [005] ..Zff 10.001014: watch: (lookup_one_qst= r_excl+0xd1/0x140) address=3D0xffff8880048083a8 value=3D0x8200080 + rm-113 [005] ..Zff 10.001018: watch: (may_delete_den= try+0x1c/0x200) address=3D0xffff8880048083a8 value=3D0x8200080 + rm-113 [005] ..Zff 10.001021: watch: (may_delete_den= try+0x195/0x200) address=3D0xffff8880048083a8 value=3D0x8200080 + rm-113 [005] ..Zff 10.001031: watch: (vfs_unlink+0x5= e/0x260) address=3D0xffff8880048083a8 value=3D0x8200080 + rm-113 [005] d.Z.. 10.001067: watch: (d_make_discard= able+0x1b/0x40) address=3D0xffff8880048083a8 value=3D0x8200080 + rm-113 [005] d.Z.. 10.001071: watch: (d_make_discard= able+0x29/0x40) address=3D0xffff8880048083a8 value=3D0x200080 + rm-113 [005] ...1. 10.001072: dentry_kill: (dentry_k= ill+0x0/0x2c0) dentry=3D0xffff8880048083a8 + rm-113 [005] ...1. 10.001218: dentry_kill: (dentry_k= ill+0x0/0x2c0) dentry=3D0xffff8880048083a8 + sh-107 [004] ...1. 10.001416: dentry_kill: (dentry_k= ill+0x0/0x2c0) dentry=3D0xffff8880049db110 + sh-107 [004] ...1. 10.001444: dentry_kill: (dentry_k= ill+0x0/0x2c0) dentry=3D0xffff8880049db248 + sh-107 [004] ...1. 10.001500: dentry_kill: (dentry_k= ill+0x0/0x2c0) dentry=3D0xffff888004ad6618 + sh-107 [004] ...1. 10.002067: dentry_kill: (dentry_k= ill+0x0/0x2c0) dentry=3D0xffff888004b41e78 + sh-107 [004] ...1. 10.904920: dentry_kill: (dentry_k= ill+0x0/0x2c0) dentry=3D0xffff888004b41e78 + sh-107 [004] ...1. 10.905129: dentry_kill: (dentry_k= ill+0x0/0x2c0) dentry=3D0xffff888004ad6618 + +You can see the watch event is correctly configured on the dentry. diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h index 43ffd9a76d88..f81a5308c116 100644 --- a/include/linux/trace_events.h +++ b/include/linux/trace_events.h @@ -738,6 +738,7 @@ enum event_trigger_type { ETT_EVENT_HIST =3D (1 << 4), ETT_HIST_ENABLE =3D (1 << 5), ETT_EVENT_EPROBE =3D (1 << 6), + ETT_EVENT_WPROBE =3D (1 << 7), }; =20 extern int filter_match_preds(struct event_filter *filter, void *rec); diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index d9b6fa5c35d9..5fd8ed63c516 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -876,6 +876,16 @@ config WPROBE_EVENTS Those events can be inserted wherever hardware breakpoints can be set, and record accessed memory address and values. =20 +config WPROBE_TRIGGERS + depends on WPROBE_EVENTS + depends on HAVE_MODIFY_LOCAL_HW_BREAKPOINT_ADDR + bool + default y + help + This adds an event trigger which will set the wprobe on a specific + field of an event. This allows user to trace the memory access of + an address pointed by the event field. + config BPF_EVENTS depends on BPF_SYSCALL depends on (KPROBE_EVENTS || UPROBE_EVENTS) && PERF_EVENTS diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 40c3e1543f6e..0a38eda359c1 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4366,6 +4366,10 @@ static const char readme_msg[] =3D "\t trigger: traceon, traceoff\n" "\t enable_event::\n" "\t disable_event::\n" +#ifdef CONFIG_WPROBE_TRIGGERS + "\t set_wprobe::[+|-]\n" + "\t clear_wprobe:[:[+|-]]\n" +#endif #ifdef CONFIG_HIST_TRIGGERS "\t enable_hist::\n" "\t disable_hist::\n" diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 18588c550a98..a61f840b18bd 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -1983,6 +1983,7 @@ trigger_data_alloc(struct event_command *cmd_ops, cha= r *cmd, char *param, void *private_data); extern void trigger_data_free(struct event_trigger_data *data); extern int event_trigger_init(struct event_trigger_data *data); +extern void event_trigger_free(struct event_trigger_data *data); extern int trace_event_trigger_enable_disable(struct trace_event_file *fil= e, int trigger_enable); extern void update_cond_flag(struct trace_event_file *file); diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_event= s_trigger.c index 149300cc5e8a..120e6ec634b7 100644 --- a/kernel/trace/trace_events_trigger.c +++ b/kernel/trace/trace_events_trigger.c @@ -589,7 +589,7 @@ int event_trigger_init(struct event_trigger_data *data) * Usually used directly as the @free method in event trigger * implementations. */ -static void +void event_trigger_free(struct event_trigger_data *data) { if (WARN_ON_ONCE(data->ref <=3D 0)) diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c index 64e7e363e8e2..77266e042418 100644 --- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c @@ -20,7 +20,7 @@ #undef C #define C(a, b) b =20 -static const char *trace_probe_err_text[] =3D { ERRORS }; +const char *trace_probe_err_text[] =3D { ERRORS }; =20 static const char *reserved_field_names[] =3D { "common_type", diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h index f20cafb87cc6..1e11077ead67 100644 --- a/kernel/trace/trace_probe.h +++ b/kernel/trace/trace_probe.h @@ -636,7 +636,12 @@ extern int traceprobe_define_arg_fields(struct trace_e= vent_call *event_call, C(TYPECAST_SYM_OFFSET, "@SYM+/-OFFSET with typecast needs parentheses"), \ C(USED_ARG_NAME, "This argument name is already used"), \ C(WPROBE_NO_MAXACT, "Watchpoint probe does not support maxactive"), \ - C(WPROBE_NO_SIBLING, "Watchpoint probe does not support sibling probes"), + C(WPROBE_NO_SIBLING, "Watchpoint probe does not support sibling probes"),= \ + C(WPROBE_ON_KPROBE, "Wprobe trigger is not supported on kprobe event"), \ + C(WPROBE_NOT_FOUND, "Target wprobe event is not found"), \ + C(WPROBE_BUSY, "Target wprobe event is already enabled"), \ + C(WPROBE_NEED_FIELD, "Wprobe trigger requires a target field"), \ + C(WPROBE_BAD_FIELD, "Target field must be pointer size"), =20 #undef C #define C(a, b) TP_ERR_##a @@ -660,6 +665,8 @@ void __trace_probe_log_err(int offset, int err); =20 DEFINE_FREE(trace_probe_log_clear, const char *, if (_T) trace_probe_log_c= lear()) =20 +extern const char *trace_probe_err_text[]; + #define trace_probe_log_err(offs, err) \ __trace_probe_log_err(offs, TP_ERR_##err) =20 diff --git a/kernel/trace/trace_wprobe.c b/kernel/trace/trace_wprobe.c index 9c6100b63e8d..3cf8786ef0ee 100644 --- a/kernel/trace/trace_wprobe.c +++ b/kernel/trace/trace_wprobe.c @@ -6,7 +6,9 @@ */ #define pr_fmt(fmt) "trace_wprobe: " fmt =20 +#include #include +#include #include #include #include @@ -15,11 +17,16 @@ #include #include #include +#include #include #include +#include +#include +#include =20 #include =20 +#include "trace.h" #include "trace_dynevent.h" #include "trace_probe.h" #include "trace_probe_kernel.h" @@ -51,6 +58,17 @@ struct trace_wprobe { int len; int type; const char *symbol; + raw_spinlock_t lock; + struct irq_work irq_work; + struct work_struct work; + atomic_t missed; + /* + * work_pending is set to 1 before irq_work_queue() and cleared to 0 + * after wprobe_work_func() finishes on_each_cpu(). This prevents a + * new trigger from overwriting tw->addr while the work is propagating + * the old address to per-CPU debug registers via IPI. + */ + atomic_t work_pending; struct trace_probe tp; }; =20 @@ -199,14 +217,65 @@ static int __register_trace_wprobe(struct trace_wprob= e *tw) static void __unregister_trace_wprobe(struct trace_wprobe *tw) { if (tw->bp_event) { + irq_work_sync(&tw->irq_work); + cancel_work_sync(&tw->work); unregister_wide_hw_breakpoint(tw->bp_event); tw->bp_event =3D NULL; } } =20 +static int trace_wprobe_update_local(struct trace_wprobe *tw, unsigned lon= g addr) +{ + struct perf_event * __percpu *pevent; + struct perf_event *bp; + + pevent =3D tw->bp_event; + if (!pevent) + return -EINVAL; + + bp =3D *this_cpu_ptr(pevent); + if (!bp) + return -EINVAL; + + return modify_local_hw_breakpoint_addr(bp, addr); +} + +static void wprobe_smp_update_func(void *info) +{ + struct trace_wprobe *tw =3D info; + unsigned long addr =3D READ_ONCE(tw->addr); + + if (trace_wprobe_update_local(tw, addr)) + atomic_inc(&tw->missed); +} + +static void wprobe_work_func(struct work_struct *work) +{ + struct trace_wprobe *tw =3D container_of(work, struct trace_wprobe, work); + + on_each_cpu(wprobe_smp_update_func, tw, true); + /* + * Clear work_pending after all CPUs have updated their local debug + * registers. A new trigger may now update tw->addr and queue a new + * irq_work. + */ + atomic_set(&tw->work_pending, 0); +} + +static void wprobe_irq_work_func(struct irq_work *irq_work) +{ + struct trace_wprobe *tw =3D container_of(irq_work, struct trace_wprobe, i= rq_work); + + schedule_work(&tw->work); +} + static void free_trace_wprobe(struct trace_wprobe *tw) { if (tw) { + if (tw->work.func) { + irq_work_sync(&tw->irq_work); + cancel_work_sync(&tw->work); + } trace_probe_cleanup(&tw->tp); kfree(tw->symbol); kfree(tw); @@ -231,6 +300,12 @@ static struct trace_wprobe *alloc_trace_wprobe(const c= har *group, if (!tw) return ERR_PTR(-ENOMEM); =20 + raw_spin_lock_init(&tw->lock); + init_irq_work(&tw->irq_work, wprobe_irq_work_func); + INIT_WORK(&tw->work, wprobe_work_func); + atomic_set(&tw->missed, 0); + atomic_set(&tw->work_pending, 0); + if (symbol) { tw->symbol =3D kstrdup(symbol, GFP_KERNEL); if (!tw->symbol) @@ -509,6 +584,11 @@ static bool trace_wprobe_is_valid_addr(unsigned long a= ddr, int len) return true; } =20 +#ifdef CONFIG_WPROBE_TRIGGERS +static u64 wprobe_trigger_clear_target __aligned(8); +#define WPROBE_DEFAULT_CLEAR_ADDRESS ((unsigned long)&wprobe_trigger_clear= _target) +#endif + static int parse_address_spec(const char *spec, unsigned long *addr, int *= type, int *len, char **symbol, int *offset) { @@ -572,7 +652,13 @@ static int parse_address_spec(const char *spec, unsign= ed long *addr, int *type, } } =20 +#ifdef CONFIG_WPROBE_TRIGGERS + if (strcmp(at + 1, "-1") =3D=3D 0) { + _addr =3D WPROBE_DEFAULT_CLEAR_ADDRESS; + } else if (kstrtoul(at + 1, 0, &_addr) !=3D 0) { +#else if (kstrtoul(at + 1, 0, &_addr) !=3D 0) { +#endif char *off_str =3D strpbrk(at + 1, "+-"); =20 if (off_str) { @@ -756,6 +842,10 @@ static int trace_wprobe_show(struct seq_file *m, struc= t dyn_event *ev) tw->offset, len); else seq_printf(m, " %s@%s:%d", type_str, tw->symbol, len); +#ifdef CONFIG_WPROBE_TRIGGERS + } else if (tw->addr =3D=3D WPROBE_DEFAULT_CLEAR_ADDRESS) { + seq_printf(m, " %s@-1:%d", type_str, len); +#endif } else { seq_printf(m, " %s@0x%lx:%d", type_str, tw->addr, len); } @@ -773,3 +863,522 @@ static __init int init_wprobe_trace(void) } fs_initcall(init_wprobe_trace); =20 +#ifdef CONFIG_WPROBE_TRIGGERS + +#define SET_WPROBE_STR "set_wprobe" +#define CLEAR_WPROBE_STR "clear_wprobe" +#define wprobe_trigger_log_err(file, glob, offs, err) \ + tracing_log_err((file)->tr, "wprobe_trigger", glob, \ + trace_probe_err_text, TP_ERR_##err, offs) + +struct wprobe_trigger_data { + struct rcu_head rcu; + struct trace_event_file *file; + struct trace_wprobe *tw; + int offset; + long adjust; + const char *field; + bool clear; +}; + +static void wprobe_trigger(struct event_trigger_data *data, + struct trace_buffer *buffer, void *rec, + struct ring_buffer_event *event) +{ + struct wprobe_trigger_data *wprobe_data =3D data->private_data; + struct trace_wprobe *tw =3D wprobe_data->tw; + unsigned long addr =3D 0, flags; + bool changed =3D false; + + if (in_nmi()) { + atomic_inc(&tw->missed); + return; + } + + if (wprobe_data->field) { + addr =3D *(unsigned long *)((char *)rec + wprobe_data->offset); + addr +=3D wprobe_data->adjust; + } + + raw_spin_lock_irqsave(&tw->lock, flags); + + if (!wprobe_data->clear) { + if (!trace_wprobe_is_valid_addr(addr, tw->len)) { + atomic_inc(&tw->missed); + goto out; + } + if (tw->addr =3D=3D WPROBE_DEFAULT_CLEAR_ADDRESS) { + /* Skip if a previous work is still propagating the address */ + if (atomic_read(&tw->work_pending)) { + atomic_inc(&tw->missed); + goto out; + } + WRITE_ONCE(tw->addr, addr); + changed =3D true; + clear_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &wprobe_data->file->flags); + } + } else { + if (tw->addr !=3D WPROBE_DEFAULT_CLEAR_ADDRESS) { + /* Skip if a previous work is still propagating the address */ + if (atomic_read(&tw->work_pending)) { + atomic_inc(&tw->missed); + goto out; + } + if (!wprobe_data->field || tw->addr =3D=3D addr) { + WRITE_ONCE(tw->addr, WPROBE_DEFAULT_CLEAR_ADDRESS); + changed =3D true; + set_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &wprobe_data->file->flags); + } + } + } + + if (changed) { + /* + * Mark the work as pending before queuing irq_work so that + * subsequent triggers skip updating tw->addr until the work + * has finished propagating the address to all CPUs. + */ + atomic_set(&tw->work_pending, 1); + irq_work_queue(&tw->irq_work); + } + +out: + raw_spin_unlock_irqrestore(&tw->lock, flags); +} + +static void free_wprobe_trigger_data(struct wprobe_trigger_data *wprobe_da= ta) +{ + if (wprobe_data) { + kfree(wprobe_data->field); + kfree(wprobe_data); + } +} +DEFINE_FREE(free_wprobe_trigger_data, struct wprobe_trigger_data *, free_w= probe_trigger_data(_T)); + +static void free_private_wprobe_trigger_data(struct event_trigger_data *da= ta) +{ + free_wprobe_trigger_data(data->private_data); +} + +static int wprobe_trigger_print(struct seq_file *m, + struct event_trigger_data *data) +{ + struct wprobe_trigger_data *wprobe_data =3D data->private_data; + int missed =3D atomic_read(&wprobe_data->tw->missed); + + if (wprobe_data->clear) { + seq_printf(m, "%s:%s", CLEAR_WPROBE_STR, + trace_event_name(wprobe_data->file->event_call)); + if (wprobe_data->field) { + seq_printf(m, ":%s%+ld", + wprobe_data->field, wprobe_data->adjust); + } + } else { + seq_printf(m, "%s:%s:%s%+ld", SET_WPROBE_STR, + trace_event_name(wprobe_data->file->event_call), + wprobe_data->field, wprobe_data->adjust); + } + + if (data->count =3D=3D -1) + seq_puts(m, ":unlimited"); + else + seq_printf(m, ":count=3D%ld", data->count); + + if (data->filter_str) + seq_printf(m, " if %s", data->filter_str); + + if (missed) + seq_printf(m, " # missed: %d", missed); + + seq_putc(m, '\n'); + + return 0; +} + +static struct wprobe_trigger_data * +wprobe_trigger_alloc(struct trace_wprobe *tw, struct trace_event_file *fil= e, + bool clear) +{ + struct wprobe_trigger_data *wprobe_data; + + wprobe_data =3D kzalloc_obj(*wprobe_data); + if (!wprobe_data) + return NULL; + + wprobe_data->tw =3D tw; + wprobe_data->clear =3D clear; + wprobe_data->file =3D file; + + return wprobe_data; +} + +static void wprobe_trigger_free(struct event_trigger_data *data) +{ + struct wprobe_trigger_data *wprobe_data =3D data->private_data; + + if (WARN_ON_ONCE(data->ref <=3D 0)) + return; + + data->ref--; + if (!data->ref) { + /* Remove the SOFT_MODE flag */ + trace_event_enable_disable(wprobe_data->file, 0, 1); + trace_event_put_ref(wprobe_data->file->event_call); + trigger_data_free(data); + } +} + +static int wprobe_trigger_cmd_parse(struct event_command *cmd_ops, + struct trace_event_file *file, + char *glob, char *cmd, + char *param_and_filter) +{ + /* + * set_wprobe:EVENT:FIELD[+OFFS] + * clear_wprobe:EVENT[:FIELD[+OFFS]] + */ + struct wprobe_trigger_data *wprobe_data =3D NULL; + struct event_trigger_data *trigger_data =3D NULL; + struct trace_event_file *wprobe_file; + struct trace_array *tr =3D file->tr; + char *event_str, *field_str, *comment; + struct ftrace_event_field *field; + struct trace_event_call *event; + bool remove, clear =3D false; + unsigned long orig_addr =3D 0; + struct trace_wprobe *tw; + char *param, *filter; + int ret; + + remove =3D event_trigger_check_remove(glob); + + if (!strcmp(cmd, CLEAR_WPROBE_STR)) + clear =3D true; + + if (param_and_filter) { + /* Recover original trigger string to show the error log correctly. */ + if (*(param_and_filter - 1) =3D=3D '\0') + *(param_and_filter - 1) =3D ':'; + comment =3D strchr(param_and_filter, '#'); + if (comment) + *comment =3D '\0'; + } + + if (event_trigger_empty_param(param_and_filter)) { + wprobe_trigger_log_err(file, glob, strlen(cmd) + 1, WPROBE_NOT_FOUND); + return -EINVAL; + } + + ret =3D event_trigger_separate_filter(param_and_filter, ¶m, &filter, = true); + if (ret) + return ret; + + if (file->event_call->flags & TRACE_EVENT_FL_KPROBE) { + wprobe_trigger_log_err(file, glob, 0, WPROBE_ON_KPROBE); + return -EOPNOTSUPP; + } + + event_str =3D strsep(¶m, ":"); + + /* Find target wprobe */ + tw =3D find_trace_wprobe(event_str, WPROBE_EVENT_SYSTEM); + if (!tw) { + wprobe_trigger_log_err(file, glob, event_str - glob, WPROBE_NOT_FOUND); + return -ENOENT; + } + /* The target wprobe must not be used (unless clear) */ + if (!remove && !clear && trace_probe_is_enabled(&tw->tp)) { + wprobe_trigger_log_err(file, glob, event_str - glob, WPROBE_BUSY); + return -EBUSY; + } + + wprobe_file =3D find_event_file(tr, WPROBE_EVENT_SYSTEM, event_str); + if (!wprobe_file) { + wprobe_trigger_log_err(file, glob, event_str - glob, WPROBE_NOT_FOUND); + return -EINVAL; + } + + wprobe_data =3D wprobe_trigger_alloc(tw, wprobe_file, clear); + if (!wprobe_data) + return -ENOMEM; + + /* clear_wprobe does not need field, but can have optional field. */ + if (!clear) { + char *offs; + + /* Find target field, which must be equivalent to "void *" */ + field_str =3D strsep(¶m, ":"); + if (!field_str) { + wprobe_trigger_log_err(file, glob, strlen(glob), WPROBE_NEED_FIELD); + ret =3D -EINVAL; + goto out_free; + } + + offs =3D strpbrk(field_str, "+-"); + if (offs) { + long val; + + if (kstrtol(offs, 0, &val) < 0) { + wprobe_trigger_log_err(file, glob, offs - glob, BAD_DEREF_OFFS); + ret =3D -EINVAL; + goto out_free; + } + wprobe_data->adjust =3D val; + *offs =3D '\0'; + } + + event =3D file->event_call; + field =3D trace_find_event_field(event, field_str); + if (!field) { + wprobe_trigger_log_err(file, glob, field_str - glob, NO_EVENT_FIELD); + ret =3D -ENOENT; + goto out_free; + } + + if (field->size !=3D sizeof(void *)) { + wprobe_trigger_log_err(file, glob, field_str - glob, WPROBE_BAD_FIELD); + ret =3D -ENOEXEC; + goto out_free; + } + wprobe_data->offset =3D field->offset; + wprobe_data->field =3D kstrdup(field_str, GFP_KERNEL); + if (!wprobe_data->field) { + ret =3D -ENOMEM; + goto out_free; + } + } else if (param && (isalpha(param[0]) || param[0] =3D=3D '_')) { + if (strncmp(param, "count=3D", 6) !=3D 0 && + strncmp(param, "unlimited", 9) !=3D 0) { + char *offs; + + field_str =3D strsep(¶m, ":"); + offs =3D strpbrk(field_str, "+-"); + if (offs) { + long val; + + if (kstrtol(offs, 0, &val) < 0) { + wprobe_trigger_log_err(file, glob, + offs - glob, + BAD_DEREF_OFFS); + ret =3D -EINVAL; + goto out_free; + } + wprobe_data->adjust =3D val; + *offs =3D '\0'; + } + + event =3D file->event_call; + field =3D trace_find_event_field(event, field_str); + if (!field) { + wprobe_trigger_log_err(file, glob, + field_str - glob, + NO_EVENT_FIELD); + ret =3D -ENOENT; + goto out_free; + } + + if (field->size !=3D sizeof(void *)) { + wprobe_trigger_log_err(file, glob, + field_str - glob, + WPROBE_BAD_FIELD); + ret =3D -ENOEXEC; + goto out_free; + } + wprobe_data->offset =3D field->offset; + wprobe_data->field =3D kstrdup(field_str, GFP_KERNEL); + if (!wprobe_data->field) { + ret =3D -ENOMEM; + goto out_free; + } + } + } + + trigger_data =3D trigger_data_alloc(cmd_ops, cmd, param, wprobe_data); + if (!trigger_data) { + ret =3D -ENOMEM; + goto out_free; + } + + trigger_data->private_data_free =3D free_private_wprobe_trigger_data; + + if (remove) { + event_trigger_unregister(cmd_ops, file, glob+1, trigger_data); + trigger_data_free(trigger_data); + return 0; + } + + /* Up the trigger_data count to make sure nothing frees it on failure */ + event_trigger_init(trigger_data); + + ret =3D event_trigger_parse_num(param, trigger_data); + if (ret) { + wprobe_trigger_log_err(file, glob, param - glob, BAD_IMM); + goto out_free_trigger; + } + + ret =3D event_trigger_set_filter(cmd_ops, file, filter, trigger_data); + if (ret < 0) + goto out_free_trigger; + + /* Soft-enable (register) wprobe event on WPROBE_DEFAULT_CLEAR_ADDRESS */ + if (!trace_event_try_get_ref(wprobe_file->event_call)) { + ret =3D -ENODEV; + goto out_free_trigger; + } + + if (!clear) { + orig_addr =3D tw->addr; + WRITE_ONCE(tw->addr, WPROBE_DEFAULT_CLEAR_ADDRESS); + } + + ret =3D trace_event_enable_disable(wprobe_file, 1, 1); + if (ret < 0) { + if (!clear) + WRITE_ONCE(tw->addr, orig_addr); + goto out_put; + } + + ret =3D event_trigger_register(cmd_ops, file, glob, trigger_data); + if (ret) + goto out_disable; + + /* Balance the event_trigger_init() at registration start */ + event_trigger_free(trigger_data); + return 0; + +out_disable: + if (!clear) + WRITE_ONCE(tw->addr, orig_addr); + trace_event_enable_disable(wprobe_file, 0, 1); +out_put: + trace_event_put_ref(wprobe_file->event_call); +out_free_trigger: + event_trigger_reset_filter(cmd_ops, trigger_data); + trigger_data_free(trigger_data); + return ret; + +out_free: + free_wprobe_trigger_data(wprobe_data); + return ret; +} + +/* Return event_trigger_data if there is a trigger which points the same w= probe */ +static struct event_trigger_data * +wprobe_trigger_find_same(struct event_trigger_data *test, + struct trace_event_file *file) +{ + struct wprobe_trigger_data *test_wprobe_data =3D test->private_data; + struct wprobe_trigger_data *wprobe_data; + struct event_trigger_data *iter; + + list_for_each_entry(iter, &file->triggers, list) { + wprobe_data =3D iter->private_data; + if (!wprobe_data || + iter->cmd_ops->trigger_type !=3D + test->cmd_ops->trigger_type) + continue; + if (wprobe_data->tw =3D=3D test_wprobe_data->tw && + wprobe_data->clear =3D=3D test_wprobe_data->clear) + return iter; + } + return NULL; +} + +static int wprobe_register_trigger(char *glob, + struct event_trigger_data *data, + struct trace_event_file *file) +{ + int ret =3D 0; + + lockdep_assert_held(&event_mutex); + + /* The same wprobe is not accept on the same file (event) */ + if (wprobe_trigger_find_same(data, file)) + return -EEXIST; + + if (data->cmd_ops->init) { + ret =3D data->cmd_ops->init(data); + if (ret < 0) + return ret; + } + + list_add_rcu(&data->list, &file->triggers); + + update_cond_flag(file); + ret =3D trace_event_trigger_enable_disable(file, 1); + if (ret < 0) { + list_del_rcu(&data->list); + update_cond_flag(file); + if (data->cmd_ops->free) + data->cmd_ops->free(data); + } + return ret; +} + +static void wprobe_unregister_trigger(char *glob, + struct event_trigger_data *test, + struct trace_event_file *file) +{ + struct event_trigger_data *data; + + lockdep_assert_held(&event_mutex); + + data =3D wprobe_trigger_find_same(test, file); + if (!data) + return; + + list_del_rcu(&data->list); + trace_event_trigger_enable_disable(file, 0); + update_cond_flag(file); + tracepoint_synchronize_unregister(); + if (data->cmd_ops->free) + data->cmd_ops->free(data); +} + +static struct event_command trigger_wprobe_set_cmd =3D { + .name =3D SET_WPROBE_STR, + .trigger_type =3D ETT_EVENT_WPROBE, + /* This triggers after when the event is recorded. */ + .flags =3D EVENT_CMD_FL_NEEDS_REC, + .parse =3D wprobe_trigger_cmd_parse, + .reg =3D wprobe_register_trigger, + .unreg =3D wprobe_unregister_trigger, + .set_filter =3D set_trigger_filter, + .trigger =3D wprobe_trigger, + .count_func =3D event_trigger_count, + .print =3D wprobe_trigger_print, + .init =3D event_trigger_init, + .free =3D wprobe_trigger_free, +}; + +static struct event_command trigger_wprobe_clear_cmd =3D { + .name =3D CLEAR_WPROBE_STR, + .trigger_type =3D ETT_EVENT_WPROBE, + /* This triggers after when the event is recorded. */ + .flags =3D EVENT_CMD_FL_NEEDS_REC, + .parse =3D wprobe_trigger_cmd_parse, + .reg =3D wprobe_register_trigger, + .unreg =3D wprobe_unregister_trigger, + .set_filter =3D set_trigger_filter, + .trigger =3D wprobe_trigger, + .count_func =3D event_trigger_count, + .print =3D wprobe_trigger_print, + .init =3D event_trigger_init, + .free =3D wprobe_trigger_free, +}; + +static __init int init_trigger_wprobe_cmds(void) +{ + int ret; + + ret =3D register_event_command(&trigger_wprobe_set_cmd); + if (WARN_ON(ret < 0)) + return ret; + ret =3D register_event_command(&trigger_wprobe_clear_cmd); + if (WARN_ON(ret < 0)) + unregister_event_command(&trigger_wprobe_set_cmd); + + return ret; +} +fs_initcall(init_trigger_wprobe_cmds); +#endif /* CONFIG_WPROBE_TRIGGERS */ From nobody Sat Sep 26 01:04:32 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 AD6513ED5D6; 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dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="LL0+/Mtz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E41AD1F00A3A; Mon, 7 Sep 2026 03:48:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788752896; bh=qR/ooNokY/JXh3TIAOrz0u1poJXQf9kNVv8StlU1sWc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=LL0+/MtznNgNOotLy2AjGLFwBejXhPp8Ja5t4UlncxGgVbfuP7HrUxj9THWRwqXb8 4OLSdGT7bSApPjdmwSX5FFmdCl5oyK60ONaoEYN0OycZl15GCDGFG4bdbSFmUAqjS4 n1ittbIrsKhc+WW2AeyiODXY/DEBDWPHJXzocE0pq6W/1R64qUPKyvqRirZrrBnzci tUs+naknWnSbLBGSXavsppzV0vz3dkS/dO+WjX4QuVfjwlGqPUR524Wau6lU41n6KP A64XIPbkTehy03O6Pq2+KhYUl2l61uH8CsqdTJW6+iy0x8/42DrejIqrumh/KcC4xI x8SsVcEB/488Q== From: "Masami Hiramatsu (Google)" To: Steven Rostedt , Peter Zijlstra , Ingo Molnar , x86@kernel.org Cc: Jinchao Wang , Mathieu Desnoyers , Masami Hiramatsu , Thomas Gleixner , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Alexander Shishkin , Ian Rogers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: [PATCH v15 10/12] selftests: tracing: Add wprobe trigger testcase Date: Mon, 7 Sep 2026 12:48:11 +0900 Message-ID: <178875289091.93794.11265683859086435623.stgit@devnote2> X-Mailer: git-send-email 2.43.0 In-Reply-To: <178875277830.93794.14247844688761142429.stgit@devnote2> References: <178875277830.93794.14247844688761142429.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Masami Hiramatsu (Google) Add a testcase for checking wprobe trigger. This sets set_wprobe and clear_wprobe triggers on fprobe event and static trace event to monitor memory accesses within the trace-events-sample kernel module. Also add a testcase for verifying wprobe trigger syntax error logging. Link: https://lore.kernel.org/all/59637b96946653393a7ad3c7de094094796b39c2.= 1785067572.git.wangjinchao600@gmail.com/ Assisted-by: Antigravity:gemini-3.8-flash Signed-off-by: Masami Hiramatsu (Google) --- Changes in v15: - Add explicit failure checks with fail helper in trigger-wprobe.tc. - Declare fprobe README requirement in trigger-wprobe.tc. - Add trigger file check to trigger-wprobe-syntax-errors.tc requires line. - Fix subject tag to tracing. Changes in v14: - Update dummy wprobe event definition to use '-1' instead of '0'. - Add BTF argument dependency requirement in trigger-wprobe.tc. - Add delay before clear_trace in trigger-wprobe.tc to avoid race with clear_wprobe trigger execution. Changes in v13: - Look up target function dynamically in trigger-wprobe-syntax-errors.tc. - Disable set_wprobe trigger before verifying clear_wprobe in trigger-wprobe.tc to avoid race condition with sample_timer_cb. Changes in v12: - Add trigger-wprobe-syntax-errors.tc for verifying wprobe trigger syntax error logging. - Fix requires line in trigger-wprobe-syntax-errors.tc so test is not evaluated as unsupported prior to execution. - Define dfd=3D$arg1 fetcharg on testevent for trigger syntax checks. Changes in v11: - Update testcase to use trace-events-sample kernel module instead of VFS file operations. --- tools/testing/selftests/ftrace/config | 1=20 .../test.d/trigger/trigger-wprobe-syntax-errors.tc | 37 +++++++ .../ftrace/test.d/trigger/trigger-wprobe.tc | 107 ++++++++++++++++= ++++ 3 files changed, 145 insertions(+) create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/trigger-w= probe-syntax-errors.tc create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/trigger-w= probe.tc diff --git a/tools/testing/selftests/ftrace/config b/tools/testing/selftest= s/ftrace/config index d2f503722020..ecdee77f360f 100644 --- a/tools/testing/selftests/ftrace/config +++ b/tools/testing/selftests/ftrace/config @@ -28,3 +28,4 @@ CONFIG_TRACER_SNAPSHOT=3Dy CONFIG_UPROBES=3Dy CONFIG_UPROBE_EVENTS=3Dy CONFIG_WPROBE_EVENTS=3Dy +CONFIG_WPROBE_TRIGGERS=3Dy diff --git a/tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe-s= yntax-errors.tc b/tools/testing/selftests/ftrace/test.d/trigger/trigger-wpr= obe-syntax-errors.tc new file mode 100644 index 000000000000..dd1ce4baa62b --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe-syntax-e= rrors.tc @@ -0,0 +1,37 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# description: event trigger - test wprobe trigger syntax errors +# requires: dynamic_events error_log "w[:[/][]] [r|w|rw]@[:]":README "f[:[/][]] [%return] []"= :README events/sched/sched_process_fork/trigger + +check_error() { # command-with-error-pos-by-^ + ftrace_errlog_check "wprobe_trigger" "$1" "events/fprobes/testevent/tr= igger" +} + +TARGET_FUNC=3D$(grep -m 1 -E -w "[tT] (vfs_read|do_sys_openat2|do_sys_open= )" /proc/kallsyms | awk '{print $3}') +if [ -z "$TARGET_FUNC" ]; then + echo "UNRESOLVED: target function not found" + exit_unresolved +fi + +# Add a dummy fprobe event to attach triggers to +echo "f:fprobes/testevent $TARGET_FUNC dfd=3D\$arg1" > dynamic_events + +# Add a target wprobe event +echo 'w:watch rw@-1:8' >> dynamic_events + +# Test errors on trigger syntax +check_error 'set_wprobe:^non_exist_wprobe:dfd' # WPROBE_NOT_FOUND +check_error 'set_wprobe:^' # WPROBE_NOT_FOUND +check_error 'set_wprobe:watch^' # WPROBE_NEED_FIELD +check_error 'set_wprobe:watch:^non_exist_field' # NO_EVENT_FIELD + +# Enable target wprobe event and test WPROBE_BUSY error +echo 1 > events/wprobes/watch/enable +check_error 'set_wprobe:^watch:dfd' # WPROBE_BUSY +echo 0 > events/wprobes/watch/enable + +# Cleanup +echo '-:watch' >> dynamic_events +echo '-:testevent' >> dynamic_events + +exit 0 diff --git a/tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe.t= c b/tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe.tc new file mode 100644 index 000000000000..043e1c915ccf --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe.tc @@ -0,0 +1,107 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# description: event trigger - test wprobe trigger +# requires: dynamic_events "w[:[/][]] [r|w|rw]@[:= ]":README "f[:[/][]] [%return] []":README ev= ents/sched/sched_process_fork/trigger "[(structname[,field])][->fi= eld[->field|.field...]]":README + +fail() { #msg + echo "$1" + exit_fail +} + +rmmod trace-events-sample ||: +if ! modprobe trace-events-sample ; then + echo "No trace-events sample module - please make CONFIG_SAMPLE_TRACE_EV= ENTS=3Dm" + exit_unresolved +fi + +cleanup_wprobe_triggers() { + if [ -f events/fprobes/testevent/trigger ]; then + reset_trigger_file events/fprobes/testevent/trigger || true + fi + if [ -f events/sample-trace/foo_bar_with_fn/trigger ]; then + reset_trigger_file events/sample-trace/foo_bar_with_fn/trigger || true + fi + echo 0 > events/enable 2>/dev/null || true + echo > dynamic_events 2>/dev/null || true + sleep 1 + rmmod trace-events-sample 2>/dev/null || true + return 0 +} + +trap cleanup_wprobe_triggers EXIT + +echo 0 > tracing_on + +# we will skip this test if fprobe is not supported. +if ! grep -Fq "f[:[/][]] [%return] []" READ= ME; then + echo "UNRESOLVED: fprobe is not supported" + exit_unresolved +fi + +# we will skip this test if the target function does not exist. +if ! grep -wq "sample_timer_cb" /proc/kallsyms; then + echo "UNRESOLVED: sample_timer_cb not found" + exit_unresolved +fi + +:;: "Add a wprobe event used by trigger" ;: +echo 'w:watch rw@-1:8 address=3D$addr value=3D$value' > dynamic_events + +:;: "Add events for triggering wprobe" ;: +echo 'f:fprobes/testevent sample_timer_cb timer=3Dt' >> dynamic_events + +:;: "Enable all events before setting triggers" ;: +echo 1 > tracing_on +echo 1 >> events/fprobes/testevent/enable +echo 1 >> events/sample-trace/foo_bar_with_fn/enable + +:;: "Set set_wprobe trigger on testevent" ;: +echo 'set_wprobe:watch:timer' >> events/fprobes/testevent/trigger +if ! grep -q ^set_wprobe events/fprobes/testevent/trigger; then + fail "Failed to set set_wprobe trigger" +fi + +# Wait for sample_timer_cb to fire and set_wprobe trigger to activate +sleep 2 + +:;: "Check set_wprobe trigger activated the watchpoint" ;: +if ! grep -q watch trace; then + fail "Failed to trigger watchpoint" +fi + +:;: "Set clear_wprobe trigger on foo_bar_with_fn" ;: +echo 'clear_wprobe:watch' >> events/sample-trace/foo_bar_with_fn/trigger +if ! grep -q ^clear_wprobe events/sample-trace/foo_bar_with_fn/trigger; th= en + fail "Failed to set clear_wprobe trigger" +fi + +# Disable set_wprobe to prevent sample_timer_cb from re-arming the watchpo= int +echo '!set_wprobe:watch:timer' >> events/fprobes/testevent/trigger + +# Wait for foo_bar_with_fn to fire and clear_wprobe trigger to deactivate = watchpoint +sleep 2 + +# Clear trace and wait to ensure no new watchpoint events are generated +clear_trace +sleep 1 + +:;: "Ensure clear_wprobe trigger deactivated the watchpoint" ;: +if grep -q watch trace; then + fail "Failed to clear watchpoint" +fi + +:;: "Remove wprobe triggers" ;: +echo '!clear_wprobe:watch' >> events/sample-trace/foo_bar_with_fn/trigger +if grep -q ^set_wprobe events/fprobes/testevent/trigger; then + fail "Failed to remove set_wprobe trigger" +fi +if grep -q ^clear_wprobe events/sample-trace/foo_bar_with_fn/trigger; then + fail "Failed to remove clear_wprobe trigger" +fi + +:;: "Disable events and remove dynamic events" ;: +echo 0 > events/enable +echo > dynamic_events +clear_trace + +exit 0 From nobody Sat Sep 26 01:04:32 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 173AE3ED5D6; Mon, 7 Sep 2026 03:48:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788752909; cv=none; b=fzSDtx03xHxPwR3QqeJ4hu7ezMy5DYNsZH0c0hY/st9CCrSVgCWkA3HrHLxuDTgm4n36x+NXLyewz78I9NhnAInw5/t85ZqZ6zgRs8hkeP/m2WcdiO51efCzM+GXMW/F/UrNMmB+9Qv5+IUXzBE0F8ZRqflyB9ibsr4vkHq2frY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788752909; c=relaxed/simple; bh=e/C78XjGWa1OTBKL/h44DVrP+RllBzkzi98oGrqxUJs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Stf+Y/sonKJ7vJhgeBKTMj4nJgAGMrut+qL4HY7Qpc9JpQhUegTIkACmiMzyX8DUcDR0v8UbiK1ADPgLoh8xeCDwkADax/nCbfpSp0gsAhDXHCKLHrUevZvPAdodSS9X7pl22y0DrCbaKCXQ0AWWwtRGTeLqznVBvPyaBF4iQdI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EHS1nP8Q; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="EHS1nP8Q" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9FEA01F00A3A; Mon, 7 Sep 2026 03:48:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788752907; bh=TrESpmidR65VjoimvstZtAP8oQ1Bl/ZOOD8urWC4AJ8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=EHS1nP8Q28/m0GXgt4Shry5bTAp/ZPkVdvWeBn+2UzoE0mopw1ULgDXsNwNVT4otb 8JxakBhXoFwhT34txFC1Ao4FRjwJ0emCGKd/WsDXQBLND894hLfoPphlhzh8YkDDk1 QoHklC/K1Pmk/4yG6Wc+FPGlLhsw5FBgnBPaA88wmCWhamakw1LgUleROr3o/7nXmX kTlLUKcmk0zZCw2LT4FIXU+z8cMIcVdnkmFRsjUwWWvoZcPeXJdeljNHX78cWZrFBU XcDQQaH513drLhQvrghrmSxNZdN1eZvzL5VRnVfYCpziIYvOHmX8G0e3iKFBboBObF oJpUkxMjfJptg== From: "Masami Hiramatsu (Google)" To: Steven Rostedt , Peter Zijlstra , Ingo Molnar , x86@kernel.org Cc: Jinchao Wang , Mathieu Desnoyers , Masami Hiramatsu , Thomas Gleixner , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Alexander Shishkin , Ian Rogers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: [PATCH v15 11/12] tracing/wprobe: Support BTF typecast in fetchargs Date: Mon, 7 Sep 2026 12:48:21 +0900 Message-ID: <178875290158.93794.6123987120712635214.stgit@devnote2> X-Mailer: git-send-email 2.43.0 In-Reply-To: <178875277830.93794.14247844688761142429.stgit@devnote2> References: <178875277830.93794.14247844688761142429.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Masami Hiramatsu (Google) Allow BTF typecast syntax (STRUCT)FETCHARG->MEMBER in wprobe event fetchargs. Previously, handle_typecast() rejected any probe context that was not a function entry/return or tracepoint event probe. Wprobe events use $addr (the accessed address) and $value (the value at that address). By enabling BTF typecast, users can now cast these to a concrete struct type and access its fields directly. For example: echo 'w:watch rw@-1:8 dflag=3D(dentry)$addr->d_flags' >> dynamic_events With a set_wprobe trigger pointing the watchpoint at a dentry address, the resulting trace shows d_flags being accessed at that location. Note that $addr and $value are restricted to kernel-space memory, which is consistent with the existing TPARG_FL_KERNEL flag used when parsing wprobe fetchargs. Assisted-by: Antigravity:gemini-3.8-flash Signed-off-by: Masami Hiramatsu (Google) --- Changes in v15: - Document BTF typecast syntax for wprobe fetchargs in wprobetrace.rst. - Add explicit failure checks with fail helper in trigger-wprobe-btf-typecast.tc. - Declare fprobe README requirement in trigger-wprobe-btf-typecast.tc. Changes in v14: - Update dummy wprobe event definition to use '-1' instead of '0'. Changes in v11: - Update trigger-wprobe-btf-typecast.tc to use trace-events-sample kernel module. - Fix commit comment. Changes in v9: - Newly added. --- Documentation/trace/wprobetrace.rst | 8 ++ kernel/trace/trace_probe.c | 13 +++ kernel/trace/trace_probe.h | 5 + tools/testing/selftests/ftrace/config | 1=20 .../test.d/trigger/trigger-wprobe-btf-typecast.tc | 85 ++++++++++++++++= ++++ 5 files changed, 111 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/trigger-w= probe-btf-typecast.tc diff --git a/Documentation/trace/wprobetrace.rst b/Documentation/trace/wpro= betrace.rst index df8985283312..20a11443c6db 100644 --- a/Documentation/trace/wprobetrace.rst +++ b/Documentation/trace/wprobetrace.rst @@ -47,6 +47,14 @@ Synopsis of wprobe-events (u8/u16/u32/u64/s8/s16/s32/s64), hexadecimal types (x8/x16/x32/x64), "char", "string", "ustring", "symbol",= "symstr" and bitfield are supported. + (STRUCT[,ASGN])FETCHARG->MEMBER[->MEMBER] : If BTF is supported, typeca= st + FETCHARG to a pointer to STRUCT and then dereference the + pointer defined by ->MEMBER. ASGN can be specified optio= nally. + If ASGN is specified, FETCHARG will be cast to the same = offset + position as the ASGN member, rather than to the beginnin= g of + the STRUCT. + (STRUCT[,ASGN])(FETCHARG)->MEMBER[->MEMBER] : typecast can nest, so the= above + can also be used with another FETCHARG. =20 (\*1) This is useful for fetching a field of data structures. (\*2) "u" means user-space dereference. diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c index 77266e042418..ccf489635ad7 100644 --- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c @@ -890,6 +890,16 @@ static int query_btf_struct(const char *sname, struct = traceprobe_parse_context * ctx->struct_btf =3D NULL; } =20 + if (ctx->btf) { + id =3D btf_find_by_name_kind(ctx->btf, sname, BTF_KIND_STRUCT); + if (id > 0) { + btf_get(ctx->btf); + ctx->struct_btf =3D ctx->btf; + ctx->last_struct =3D btf_type_by_id(ctx->struct_btf, id); + return 0; + } + } + id =3D bpf_find_btf_id(sname, BTF_KIND_STRUCT, &btf); if (id < 0) return id; @@ -965,7 +975,8 @@ static int handle_typecast(char *arg, struct traceprobe= _parse_context *ctx) =20 if (!(tparg_is_event_probe(ctx->flags) || tparg_is_function_entry(ctx->flags) || - tparg_is_function_return(ctx->flags))) { + tparg_is_function_return(ctx->flags) || + tparg_is_wprobe(ctx->flags))) { trace_probe_log_err(ctx->offset, NOSUP_BTFARG); return -EOPNOTSUPP; } diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h index 1e11077ead67..c54c554b1949 100644 --- a/kernel/trace/trace_probe.h +++ b/kernel/trace/trace_probe.h @@ -439,6 +439,11 @@ static inline bool tparg_is_event_probe(unsigned int f= lags) return !!(flags & TPARG_FL_TEVENT); } =20 +static inline bool tparg_is_wprobe(unsigned int flags) +{ + return !!(flags & TPARG_FL_WPROBE); +} + /* Each typecast consumes nested level. So the max number of typecast is 8= . */ #define TRACEPROBE_MAX_NESTED_LEVEL 8 =20 diff --git a/tools/testing/selftests/ftrace/config b/tools/testing/selftest= s/ftrace/config index ecdee77f360f..f067874902ed 100644 --- a/tools/testing/selftests/ftrace/config +++ b/tools/testing/selftests/ftrace/config @@ -1,5 +1,6 @@ CONFIG_BPF_SYSCALL=3Dy CONFIG_DEBUG_INFO_BTF=3Dy +CONFIG_DEBUG_INFO_BTF_MODULES=3Dy CONFIG_DEBUG_INFO_DWARF4=3Dy CONFIG_EPROBE_EVENTS=3Dy CONFIG_FPROBE=3Dy diff --git a/tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe-b= tf-typecast.tc b/tools/testing/selftests/ftrace/test.d/trigger/trigger-wpro= be-btf-typecast.tc new file mode 100644 index 000000000000..3d4c9fd6b8e2 --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe-btf-type= cast.tc @@ -0,0 +1,85 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# description: event trigger - test wprobe trigger with BTF typecast fetch= args +# requires: dynamic_events "w[:[/][]] [r|w|rw]@[:= ]":README "f[:[/][]] [%return] []":README ev= ents/sched/sched_process_fork/trigger "[(structname[,field])][->fi= eld[->field|.field...]]":README + +fail() { #msg + echo "$1" + exit_fail +} + +rmmod trace-events-sample ||: +if ! modprobe trace-events-sample ; then + echo "No trace-events sample module - please make CONFIG_SAMPLE_TRACE_EV= ENTS=3Dm" + exit_unresolved +fi + +cleanup_wprobe_triggers() { + if [ -f events/fprobes/testevent/trigger ]; then + reset_trigger_file events/fprobes/testevent/trigger || true + fi + echo 0 > events/enable 2>/dev/null || true + echo > dynamic_events 2>/dev/null || true + sleep 1 + rmmod trace-events-sample 2>/dev/null || true + return 0 +} + +trap cleanup_wprobe_triggers EXIT + +echo 0 > tracing_on + +# we will skip this test if fprobe is not supported. +if ! grep -Fq "f[:[/][]] [%return] []" READ= ME; then + echo "UNRESOLVED: fprobe is not supported" + exit_unresolved +fi + +# we will skip this test if the target function does not exist. +if ! grep -wq "sample_timer_cb" /proc/kallsyms; then + echo "UNRESOLVED: sample_timer_cb not found" + exit_unresolved +fi + +:;: "Add a wprobe event with BTF typecast fetchargs" ;: +# (foo_timer_data,timer)$addr->counter reads counter from struct foo_timer= _data via BTF typecast +echo 'w:watch rw@-1:8 address=3D$addr counter=3D(foo_timer_data,timer)$add= r->counter' >> dynamic_events + +:;: "Check the wprobe event is registered with counter field" ;: +if ! grep -q "counter" dynamic_events; then + fail "Failed to register counter field in dynamic_events" +fi + +:;: "Add fprobe event for sample_timer_cb" ;: +echo 'f:fprobes/testevent sample_timer_cb timer=3Dt' >> dynamic_events + +:;: "Enable all events before setting triggers" ;: +echo 1 > tracing_on +echo 1 >> events/fprobes/testevent/enable + +:;: "Set set_wprobe trigger on testevent" ;: +echo 'set_wprobe:watch:timer' >> events/fprobes/testevent/trigger +if ! grep -q ^set_wprobe events/fprobes/testevent/trigger; then + fail "Failed to set set_wprobe trigger" +fi + +# Wait for sample_timer_cb to fire and set_wprobe trigger to activate +sleep 3 + +:;: "Check set_wprobe trigger activated the watchpoint" ;: +if ! grep -q watch trace; then + fail "Failed to trigger watchpoint" +fi + +:;: "Remove wprobe triggers" ;: +echo '!set_wprobe:watch:timer' >> events/fprobes/testevent/trigger +if grep -q ^set_wprobe events/fprobes/testevent/trigger; then + fail "Failed to remove set_wprobe trigger" +fi + +:;: "Disable events and remove dynamic events" ;: +echo 0 > events/enable +echo > dynamic_events +clear_trace + +exit 0 From nobody Sat Sep 26 01:04:32 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 0B3963EC833; Mon, 7 Sep 2026 03:48:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788752920; cv=none; b=al5QBN5ybehswdO1L6+ZCFXMESgSVpj6XDHdv/B6WImx+HHU5efaGy+34fZMCa6caGElqlQzzGQZwESwaQ/O6XTZAFAwRcyoaaceOi01DFsERCKH6TrTz0i8FW2tn0Ssl1Jf0DwTpN79H97d3QEex7rP32XEyIXi2GFO3v7Jydk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788752920; c=relaxed/simple; bh=xTVQGGIwjiOXMhjB3YCzr7YHX1vUKy0x9+c9UcqxLt0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=uPQhNQxdwCi4ftFhC5poG9BXprAS0hUj14iuRzDVsMeaMSTmfrW9xrkKK6oSBlIh/RgUPNoKxdsmOuSFfswk1rLFUjMbXPXRKw5RECaOV7RaZYivjTFaOunYYiorO2OE5+ricLx368wp6QBvrkF3X0g16GX5YbdHzIXmK3QGJHg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=NWdYsfuv; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="NWdYsfuv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 89F491F00A3A; Mon, 7 Sep 2026 03:48:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788752918; bh=On86txE9Jv1brahg8dH8EYfHnEYs69+hOzkS5AOZwdo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=NWdYsfuv+w+3atBlCGJODLfdkwcMMc/ya10J+t0b7OBo3h9SmB9KrpDK6w7pvvRIs GSQvuOXS75NdHGanPvECQ0dq/kc+irBlAtsJINgrCs1KYVP34UczvhtayqVF8KWhVR 5rmH7zXXoGX8qq3MCLyUHBRJWAFfd7jep85fxRGJyTwHISsbxKKRbUpScpaYrlyBVF ByP5p5DqU0vMqx5+GFKayZAcCz2ikdjXe49QHcHNheqvkBrwqHl/HeKiGYQL/V0FL9 Gp1U9VZuQxFU4Qt9gcnwZGwaweSAB7Rwq7IjdTos3AtZplxMenpfXX0ZSx+OjzDPUa Xao+jBzNNlfmQ== From: "Masami Hiramatsu (Google)" To: Steven Rostedt , Peter Zijlstra , Ingo Molnar , x86@kernel.org Cc: Jinchao Wang , Mathieu Desnoyers , Masami Hiramatsu , Thomas Gleixner , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Alexander Shishkin , Ian Rogers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: [PATCH v15 12/12] tracing/wprobe: Support BTF struct offset resolution in set_wprobe trigger Date: Mon, 7 Sep 2026 12:48:33 +0900 Message-ID: <178875291323.93794.16645737472750929830.stgit@devnote2> X-Mailer: git-send-email 2.43.0 In-Reply-To: <178875277830.93794.14247844688761142429.stgit@devnote2> References: <178875277830.93794.14247844688761142429.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Masami Hiramatsu (Google) Allow set_wprobe trigger to use BTF struct offset resolution to specify the target address field. Link: https://lore.kernel.org/all/59637b96946653393a7ad3c7de094094796b39c2.= 1785067572.git.wangjinchao600@gmail.com/ Assisted-by: Antigravity:gemini-3.8-flash Signed-off-by: Masami Hiramatsu (Google) --- Changes in v15: - Duplicate field string to avoid modifying glob in place in wprobe_trigger_typecast_parse() so tracing_log_err() prints pristine command string. - Remove leftover offset and adjust debug print in wprobe_trigger_print(). - Document BTF struct offset resolution syntax in wprobetrace.rst. - Add explicit failure checks with fail helper in trigger-wprobe-btf-offset.tc. - Declare fprobe README requirement in trigger-wprobe-btf-offset.tc. Changes in v14: - Update dummy wprobe event definition to use '-1' instead of '0'. - Pass member_type to btf_find_struct_member() and check its kflag in get_offset_of_field(). Changes in v13: - Check for field token before calling wprobe_trigger_field_parse() in clear_wprobe to avoid spurious error log entries on numeric counts. Changes in v12: - Refactor field parsing logic into wprobe_trigger_field_parse(). - Remove unused variable count_str in wprobe_trigger_cmd_parse(). --- Documentation/trace/wprobetrace.rst | 7=20 kernel/trace/trace_wprobe.c | 294 +++++++++++++++-= ---- .../test.d/trigger/trigger-wprobe-btf-offset.tc | 85 ++++++ 3 files changed, 308 insertions(+), 78 deletions(-) create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/trigger-w= probe-btf-offset.tc diff --git a/Documentation/trace/wprobetrace.rst b/Documentation/trace/wpro= betrace.rst index 20a11443c6db..1d9b32d02d53 100644 --- a/Documentation/trace/wprobetrace.rst +++ b/Documentation/trace/wprobetrace.rst @@ -90,10 +90,17 @@ Combination with trigger action The event trigger action can extend the utilization of this wprobe. =20 - set_wprobe:WPEVENT:FIELD[+|-ADJUST][:COUNT] +- set_wprobe:WPEVENT:(STRUCT[,ASGN])EVENT_FIELD->MEMBER[+|-ADJUST][:COUNT] - clear_wprobe:WPEVENT[:FIELD[+|-ADJUST][:COUNT]] +- clear_wprobe:WPEVENT[:(STRUCT[,ASGN])EVENT_FIELD->MEMBER[+|-ADJUST][:COU= NT]] =20 Set these triggers to the target event, then the WPROBE event will be setup to trace the memory access at FIELD[+|-ADJUST] address. +If BTF is supported, the target address can also be resolved using BTF +struct offset resolution: `(STRUCT[,ASGN])EVENT_FIELD->MEMBER[+|-ADJUST]`. +Here, EVENT_FIELD is an event field containing a pointer to STRUCT (or to +the ASGN member if ASGN is specified), and MEMBER is the struct member who= se +offset is resolved automatically via BTF. When clear_wprobe is hit, if FIELD is NOT specified, the WPEVENT is forcibly cleared. If FIELD[+|-ADJUST] is set, it clears WPEVENT only if its watching address is the same as the FIELD[+|-ADJUST] value. diff --git a/kernel/trace/trace_wprobe.c b/kernel/trace/trace_wprobe.c index 3cf8786ef0ee..373cfd1640dd 100644 --- a/kernel/trace/trace_wprobe.c +++ b/kernel/trace/trace_wprobe.c @@ -27,6 +27,7 @@ #include =20 #include "trace.h" +#include "trace_btf.h" #include "trace_dynevent.h" #include "trace_probe.h" #include "trace_probe_kernel.h" @@ -1028,6 +1029,213 @@ static void wprobe_trigger_free(struct event_trigge= r_data *data) } } =20 +#ifdef CONFIG_PROBE_EVENTS_BTF_ARGS + +static int get_offset_of_field(struct btf *btf, const struct btf_type *typ= e, char *field_name) +{ + const struct btf_member *field; + const struct btf_type *mtype; + int bitoffs =3D 0; + u32 anon_offs; + char *next; + + do { + next =3D strchr(field_name, '.'); + if (next) + *next++ =3D '\0'; + + field =3D btf_find_struct_member(btf, type, field_name, &anon_offs, &mty= pe); + if (IS_ERR_OR_NULL(field)) + return -ENOENT; + + if (btf_type_kflag(mtype)) { + /* Reject bitfield member access */ + if (BTF_MEMBER_BITFIELD_SIZE(field->offset)) + return -EINVAL; + bitoffs +=3D anon_offs + BTF_MEMBER_BIT_OFFSET(field->offset); + } else { + bitoffs +=3D anon_offs + field->offset; + } + + field_name =3D next; + if (next) { + type =3D btf_type_skip_modifiers(btf, field->type, NULL); + if (!type) + return -ENOENT; + } + } while (next); + return bitoffs / BITS_PER_BYTE; +} + +/* btf_put(NULL) is acceptable. */ +DEFINE_FREE(btf_put, struct btf *, btf_put(_T)) + +/* parse typecast: (TYPE[,ASGN])EVENT_FIELD->FIELD[.SUBFIELD...][+-OFFS] a= nd set adjust. */ +static int wprobe_trigger_typecast_parse(char *field_str, + struct trace_event_file *file, + struct wprobe_trigger_data *wprobe_data, + const char *glob) +{ + struct btf *btf __free(btf_put) =3D NULL; + char *buf __free(kfree) =3D NULL; + struct ftrace_event_field *field; + const struct btf_type *type; + char *assign_field; + char *event_field; + char *type_field; + char *type_name; + char *offs; + long val =3D 0; + int base_offset =3D field_str - glob; + int event_field_offset; + int id, adjust; + + buf =3D kstrdup(field_str, GFP_KERNEL); + if (!buf) + return -ENOMEM; + + type_name =3D buf + 1; + event_field =3D strchr(type_name, ')'); + if (!event_field) { + wprobe_trigger_log_err(file, glob, + base_offset + (type_name - buf), + DEREF_OPEN_BRACE); + return -EINVAL; + } + *event_field++ =3D '\0'; + + /* Check the optional assign field. */ + assign_field =3D strchr(type_name, ','); + if (assign_field) + *assign_field++ =3D '\0'; + + /* Get the type field name. */ + type_field =3D strstr(event_field, "->"); + if (!type_field) { + wprobe_trigger_log_err(file, glob, + base_offset + (event_field - buf), + TYPECAST_REQ_FIELD); + return -EINVAL; + } + *type_field =3D '\0'; + type_field +=3D 2; + + offs =3D strpbrk(type_field, "+-"); + if (offs) { + if (kstrtol(offs, 0, &val) < 0) { + wprobe_trigger_log_err(file, glob, + base_offset + (offs - buf), + BAD_DEREF_OFFS); + return -EINVAL; + } + *offs =3D '\0'; + } + + /* find type from BTF */ + id =3D bpf_find_btf_id(type_name, BTF_KIND_STRUCT, &btf); + if (id < 0) { + wprobe_trigger_log_err(file, glob, + base_offset + (type_name - buf), + BAD_BTF_TID); + return id; + } + + type =3D btf_type_by_id(btf, id); + if (!type) { + wprobe_trigger_log_err(file, glob, + base_offset + (type_name - buf), + BAD_BTF_TID); + return -EINVAL; + } + + adjust =3D get_offset_of_field(btf, type, type_field); + if (adjust < 0) { + wprobe_trigger_log_err(file, glob, + base_offset + (type_field - buf), + NO_BTF_FIELD); + return adjust; + } + wprobe_data->adjust =3D adjust + val; + + if (assign_field) { + /* assign_field should be a struct field */ + adjust =3D get_offset_of_field(btf, type, assign_field); + if (adjust < 0) { + wprobe_trigger_log_err(file, glob, + base_offset + (assign_field - buf), + NO_BTF_FIELD); + return adjust; + } + wprobe_data->adjust -=3D adjust; + } + + event_field_offset =3D base_offset + (event_field - buf); + field =3D trace_find_event_field(file->event_call, event_field); + if (!field) { + wprobe_trigger_log_err(file, glob, event_field_offset, NO_EVENT_FIELD); + return -ENOENT; + } + if (field->size !=3D sizeof(void *)) { + wprobe_trigger_log_err(file, glob, event_field_offset, WPROBE_BAD_FIELD); + return -ENOEXEC; + } + wprobe_data->offset =3D field->offset; + wprobe_data->field =3D kstrdup(event_field, GFP_KERNEL); + if (!wprobe_data->field) + return -ENOMEM; + + return 0; +} +#else +static int wprobe_trigger_typecast_parse(char *field_str, + struct trace_event_file *file, + struct wprobe_trigger_data *wprobe_data, + const char *glob) +{ + wprobe_trigger_log_err(file, glob, field_str - glob, NOSUP_BTFARG); + return -EOPNOTSUPP; +} +#endif /* CONFIG_PROBE_EVENTS_BTF_ARGS */ + +static int wprobe_trigger_field_parse(char *field_str, struct trace_event_= file *file, + struct wprobe_trigger_data *wprobe_data, + const char *glob) +{ + struct ftrace_event_field *field; + char *offs; + + if (field_str[0] =3D=3D '(') + return wprobe_trigger_typecast_parse(field_str, file, wprobe_data, glob); + + offs =3D strpbrk(field_str, "+-"); + if (offs) { + long val; + + if (kstrtol(offs, 0, &val) < 0) { + wprobe_trigger_log_err(file, glob, offs - glob, BAD_DEREF_OFFS); + return -EINVAL; + } + wprobe_data->adjust =3D val; + *offs =3D '\0'; + } + + field =3D trace_find_event_field(file->event_call, field_str); + if (!field) { + wprobe_trigger_log_err(file, glob, field_str - glob, NO_EVENT_FIELD); + return -ENOENT; + } + if (field->size !=3D sizeof(void *)) { + wprobe_trigger_log_err(file, glob, field_str - glob, WPROBE_BAD_FIELD); + return -ENOEXEC; + } + wprobe_data->offset =3D field->offset; + wprobe_data->field =3D kstrdup(field_str, GFP_KERNEL); + if (!wprobe_data->field) + return -ENOMEM; + + return 0; +} + static int wprobe_trigger_cmd_parse(struct event_command *cmd_ops, struct trace_event_file *file, char *glob, char *cmd, @@ -1040,10 +1248,8 @@ static int wprobe_trigger_cmd_parse(struct event_com= mand *cmd_ops, struct wprobe_trigger_data *wprobe_data =3D NULL; struct event_trigger_data *trigger_data =3D NULL; struct trace_event_file *wprobe_file; + char *event_str, *comment; struct trace_array *tr =3D file->tr; - char *event_str, *field_str, *comment; - struct ftrace_event_field *field; - struct trace_event_call *event; bool remove, clear =3D false; unsigned long orig_addr =3D 0; struct trace_wprobe *tw; @@ -1104,92 +1310,24 @@ static int wprobe_trigger_cmd_parse(struct event_co= mmand *cmd_ops, =20 /* clear_wprobe does not need field, but can have optional field. */ if (!clear) { - char *offs; + char *field_str =3D strsep(¶m, ":"); =20 - /* Find target field, which must be equivalent to "void *" */ - field_str =3D strsep(¶m, ":"); if (!field_str) { wprobe_trigger_log_err(file, glob, strlen(glob), WPROBE_NEED_FIELD); ret =3D -EINVAL; goto out_free; } - - offs =3D strpbrk(field_str, "+-"); - if (offs) { - long val; - - if (kstrtol(offs, 0, &val) < 0) { - wprobe_trigger_log_err(file, glob, offs - glob, BAD_DEREF_OFFS); - ret =3D -EINVAL; - goto out_free; - } - wprobe_data->adjust =3D val; - *offs =3D '\0'; - } - - event =3D file->event_call; - field =3D trace_find_event_field(event, field_str); - if (!field) { - wprobe_trigger_log_err(file, glob, field_str - glob, NO_EVENT_FIELD); - ret =3D -ENOENT; - goto out_free; - } - - if (field->size !=3D sizeof(void *)) { - wprobe_trigger_log_err(file, glob, field_str - glob, WPROBE_BAD_FIELD); - ret =3D -ENOEXEC; - goto out_free; - } - wprobe_data->offset =3D field->offset; - wprobe_data->field =3D kstrdup(field_str, GFP_KERNEL); - if (!wprobe_data->field) { - ret =3D -ENOMEM; + ret =3D wprobe_trigger_field_parse(field_str, file, wprobe_data, glob); + if (ret < 0) goto out_free; - } - } else if (param && (isalpha(param[0]) || param[0] =3D=3D '_')) { + } else if (param && (isalpha(param[0]) || param[0] =3D=3D '_' || param[0]= =3D=3D '(')) { if (strncmp(param, "count=3D", 6) !=3D 0 && strncmp(param, "unlimited", 9) !=3D 0) { - char *offs; - - field_str =3D strsep(¶m, ":"); - offs =3D strpbrk(field_str, "+-"); - if (offs) { - long val; - - if (kstrtol(offs, 0, &val) < 0) { - wprobe_trigger_log_err(file, glob, - offs - glob, - BAD_DEREF_OFFS); - ret =3D -EINVAL; - goto out_free; - } - wprobe_data->adjust =3D val; - *offs =3D '\0'; - } - - event =3D file->event_call; - field =3D trace_find_event_field(event, field_str); - if (!field) { - wprobe_trigger_log_err(file, glob, - field_str - glob, - NO_EVENT_FIELD); - ret =3D -ENOENT; - goto out_free; - } + char *field_str =3D strsep(¶m, ":"); =20 - if (field->size !=3D sizeof(void *)) { - wprobe_trigger_log_err(file, glob, - field_str - glob, - WPROBE_BAD_FIELD); - ret =3D -ENOEXEC; + ret =3D wprobe_trigger_field_parse(field_str, file, wprobe_data, glob); + if (ret < 0) goto out_free; - } - wprobe_data->offset =3D field->offset; - wprobe_data->field =3D kstrdup(field_str, GFP_KERNEL); - if (!wprobe_data->field) { - ret =3D -ENOMEM; - goto out_free; - } } } =20 diff --git a/tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe-b= tf-offset.tc b/tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe= -btf-offset.tc new file mode 100644 index 000000000000..8bc8ca02a712 --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe-btf-offs= et.tc @@ -0,0 +1,85 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# description: event trigger - test set_wprobe trigger with BTF struct off= set +# requires: dynamic_events "w[:[/][]] [r|w|rw]@[:= ]":README "f[:[/][]] [%return] []":README ev= ents/sched/sched_process_fork/trigger "[(structname[,field])][->fi= eld[->field|.field...]]":README + +fail() { #msg + echo "$1" + exit_fail +} + +rmmod trace-events-sample ||: +if ! modprobe trace-events-sample ; then + echo "No trace-events sample module - please make CONFIG_SAMPLE_TRACE_EV= ENTS=3Dm" + exit_unresolved +fi + +cleanup_wprobe_triggers() { + if [ -f events/fprobes/testevent/trigger ]; then + reset_trigger_file events/fprobes/testevent/trigger || true + fi + echo 0 > events/enable 2>/dev/null || true + echo > dynamic_events 2>/dev/null || true + sleep 1 + rmmod trace-events-sample 2>/dev/null || true + return 0 +} + +trap cleanup_wprobe_triggers EXIT + +echo 0 > tracing_on + +# we will skip this test if fprobe is not supported. +if ! grep -Fq "f[:[/][]] [%return] []" READ= ME; then + echo "UNRESOLVED: fprobe is not supported" + exit_unresolved +fi + +# we will skip this test if the target function does not exist. +if ! grep -wq "sample_timer_cb" /proc/kallsyms; then + echo "UNRESOLVED: sample_timer_cb not found" + exit_unresolved +fi + +:;: "Add a wprobe event watching 8 bytes" ;: +echo 'w:watch rw@-1:8 address=3D$addr value=3D$value' >> dynamic_events + +:;: "Add fprobe event for sample_timer_cb" ;: +# sample_timer_cb(struct timer_list *t) +# container_of(t, struct foo_timer_data, timer) +echo 'f:fprobes/testevent sample_timer_cb timer=3Dt' >> dynamic_events + +:;: "Enable all events before setting triggers" ;: +echo 1 > tracing_on +echo 1 >> events/fprobes/testevent/enable + +:;: "Set set_wprobe trigger using BTF struct offset resolution" ;: +# Syntax: set_wprobe:WPEVENT:(STRUCT,FIELD)EVENT_FIELD->MEMBER +# (foo_timer_data,timer) is the BTF struct type and field name +# timer->expires is the struct member whose offset is resolved automatical= ly via BTF +echo 'set_wprobe:watch:(foo_timer_data,timer)timer->timer.expires' >> even= ts/fprobes/testevent/trigger +if ! grep -q ^set_wprobe events/fprobes/testevent/trigger; then + fail "Failed to set set_wprobe trigger" +fi + +# Wait for sample_timer_cb to fire and set_wprobe trigger to activate +sleep 3 + +:;: "Check set_wprobe trigger activated the watchpoint" ;: +if ! grep -q watch trace; then + fail "Failed to trigger watchpoint" +fi + +:;: "Remove wprobe triggers" ;: +# Since we don't know actual offset of timer->expires in foo_timer_data, w= e use reset_trigger_file +reset_trigger_file events/fprobes/testevent/trigger +if grep -q ^set_wprobe events/fprobes/testevent/trigger; then + fail "Failed to remove set_wprobe trigger" +fi + +:;: "Disable events and remove dynamic events" ;: +echo 0 > events/enable +echo > dynamic_events +clear_trace + +exit 0