From mboxrd@z Thu Jan 1 00:00:00 1970 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 5B6CC2E8897; Wed, 15 Jul 2026 01:44:05 +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=1784079846; cv=none; b=CDonKda7DgsGsR1el1Yuc6Ezk1DMeuNb0D04+4QrjF7ShQ1wgJA7Zi50fLHCTwFji3pXSph+5czI7t2PJM32vhbDluzgv6SxyqIFZJT997tNO1U5M26gDY3s4nbm/T0R6O/yXQsJhEVpvae3pJINUHZb3I97z4hG6UTqcSQGcSY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784079846; c=relaxed/simple; bh=HdJ16PbWwtziGIxqJSkxrG3R0YrasbU4/9EtLdT7PvA=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=uLeGzybYMNr7JS6/NwFLQUnt7j+qxeGQtv4LVVlirRfIcZWbwyOHDe0lKCKdjOJ1uX3140gVcDqKeUQ44Wt+7iybs5SARclBHpBJ1VMdOpHwraElXC7FYE72qcTP42LlGcbVMWHQtSlcrypZZdcEgnmfCiASw35Ko8tbcqe9ml8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nwscs4xH; 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="nwscs4xH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 570081F000E9; Wed, 15 Jul 2026 01:44:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784079845; bh=/9dm46gWhRkyn2A6l+59OoIXgM8MWHtfOTJR//oBE58=; h=From:To:Cc:Subject:Date; b=nwscs4xHRgRMQwuQzxvjuGNNadEa+vbWFbBbO6CuIWLWKKr/ShU3N026fnFw//cQ4 DGrMCtQc38oxeBdbW0fPOJsuFBisp5wtONp9ibO7vqMpvsJ0VR+T5Wc2FggAWQZBT+ hm6Ok3gZxAy2q+xNx2h7yAo19FRbx6prXF+yzNeoAO1379OIdmWAhIzFu/PdoBU/6m 6P1/PnZgO49sWH5TMK2i6a09pgZfBVzUWTGY5mm0m8v4D+cjHQZXJ+wIba7HeJAHea DgHDGGZq+XHCeHv23S5ATZDTfaxyhEMIbwjsdvEBD7WciSq4mreH1BjoVwqt5ko55G 5TnwP3P3EbUqw== 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 v7 00/10] tracing: wprobe: x86: Add wprobe for watchpoint Date: Wed, 15 Jul 2026 10:43:58 +0900 Message-ID: <178407983818.95826.12714571928538799781.stgit@devnote2> X-Mailer: git-send-email 2.43.0 User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Hi, Here is the 7th version of the series for adding new wprobe (watch probe) which provides memory access tracing event. Moreover, this can be used via event trigger. Thus it can trace memory access on a dynamically allocated objects too. The previous version is here: https://lore.kernel.org/all/176960933881.182525.11984731584313026309.stgit@devnote2/ This version is rebased on top of probes/for-next branch, fold IS_ERR_PCPU fix and fix some checkpatch.pl related issue (not all, some of them seems wrong warnings). Other updates: - Fix a race on wprobe handler using bp->attr.bp_addr instead of tw->addr. - Fix modify_wide_hw_breakpoint_local() to update bp->attr.bp_addr. - Return -EOPNOTSUPP instead of -ENOSYS. (that is not a syscall function) - Update test script to use dentry_kill instead of __dentry_kill. To support arm64, we need to avoid major pagefault on single-stepping issue. I think we can solve it with checking whether the address is the kernel (which must not cause a major page fault), or not. Usage ----- The basic usage of this wprobe is similar to other probes; w:[GRP/][EVENT] [r|w|rw]@ [FETCHARGS] This defines a new wprobe event. For example, to trace jiffies update, you can do; echo 'w:my_jiffies w@jiffies:8 value=+0($addr)' >> dynamic_events echo 1 > events/wprobes/my_jiffies/enable Moreover, this can be combined with event trigger to trace the memory accecss on slab objects. The trigger syntax is; set_wprobe:WPROBE_EVENT:FIELD[+OFFSET] [if FILTER] clear_wprobe:WPROBE_EVENT[:FIELD[+OFFSET]] [if FILTER] set_wprobe sets WPROBE_EVENT's watch address on FIELD[+OFFSET]. clear_wprobe clears WPROBE_EVENT's watch address if it is set to FIELD[+OFFSET]. If FIELD is omitted, forcibly clear the watch address when trigger event is hit. For example, trace the first 8 byte of the dentry data structure passed to do_truncate() until it is deleted by __dentry_kill(). (Note: all tracefs setup uses '>>' so that it does not kick do_truncate()) # echo 'w:watch rw@0:8 address=$addr value=+0($addr)' > dynamic_events # echo 'f:truncate do_truncate dentry=$arg2' >> dynamic_events # echo 'set_wprobe:watch:dentry' >> events/fprobes/truncate/trigger # echo 'f:dentry_kill __dentry_kill dentry=$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: 16/16 #P:8 # # _-----=> irqs-off/BH-disabled # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / _-=> migrate-disable # |||| / delay # TASK-PID CPU# ||||| TIMESTAMP FUNCTION # | | | ||||| | | sh-113 [004] ..... 6.467444: truncate: (do_truncate+0x4/0x120) dentry=0xffff8880044f0fd8 sh-113 [004] ..Zff 6.468534: watch: (lookup_fast+0xaa/0x150) address=0xffff8880044f0fd8 value=0x200080 sh-113 [004] ..Zff 6.468542: watch: (step_into+0x82/0x360) address=0xffff8880044f0fd8 value=0x200080 sh-113 [004] ..Zff 6.468547: watch: (step_into+0x9f/0x360) address=0xffff8880044f0fd8 value=0x200080 sh-113 [004] ..Zff 6.468553: watch: (path_openat+0xb3a/0xe70) address=0xffff8880044f0fd8 value=0x200080 sh-113 [004] ..Zff 6.468557: watch: (path_openat+0xb9a/0xe70) address=0xffff8880044f0fd8 value=0x200080 sh-113 [004] ..... 6.468563: truncate: (do_truncate+0x4/0x120) dentry=0xffff8880044f0fd8 sh-113 [004] ...1. 6.469826: dentry_kill: (__dentry_kill+0x0/0x220) dentry=0xffff8880044f0ea0 sh-113 [004] ...1. 6.469859: dentry_kill: (__dentry_kill+0x0/0x220) dentry=0xffff8880044f0d68 rm-118 [001] ..Zff 6.472360: watch: (lookup_fast+0xaa/0x150) address=0xffff8880044f0fd8 value=0x200080 rm-118 [001] ..Zff 6.472366: watch: (step_into+0x82/0x360) address=0xffff8880044f0fd8 value=0x200080 rm-118 [001] ..Zff 6.472370: watch: (step_into+0x9f/0x360) address=0xffff8880044f0fd8 value=0x200080 rm-118 [001] ..Zff 6.472386: watch: (lookup_fast+0xaa/0x150) address=0xffff8880044f0fd8 value=0x200080 rm-118 [001] ..Zff 6.472390: watch: (step_into+0x82/0x360) address=0xffff8880044f0fd8 value=0x200080 rm-118 [001] ..Zff 6.472394: watch: (step_into+0x9f/0x360) address=0xffff8880044f0fd8 value=0x200080 rm-118 [001] ..Zff 6.472415: watch: (lookup_one_qstr_excl+0x2c/0x150) address=0xffff8880044f0fd8 value=0x200080 rm-118 [001] ..Zff 6.472419: watch: (lookup_one_qstr_excl+0xd5/0x150) address=0xffff8880044f0fd8 value=0x200080 rm-118 [001] ..Zff 6.472424: watch: (may_delete+0x18/0x200) address=0xffff8880044f0fd8 value=0x200080 rm-118 [001] ..Zff 6.472428: watch: (may_delete+0x194/0x200) address=0xffff8880044f0fd8 value=0x200080 rm-118 [001] ..Zff 6.472446: watch: (vfs_unlink+0x63/0x1c0) address=0xffff8880044f0fd8 value=0x200080 rm-118 [001] d.Z.. 6.472528: watch: (dont_mount+0x19/0x30) address=0xffff8880044f0fd8 value=0x200180 rm-118 [001] ..Zff 6.472533: watch: (vfs_unlink+0x11a/0x1c0) address=0xffff8880044f0fd8 value=0x200180 rm-118 [001] ..Zff 6.472538: watch: (vfs_unlink+0x12e/0x1c0) address=0xffff8880044f0fd8 value=0x200180 rm-118 [001] d.Z1. 6.472543: watch: (d_delete+0x61/0xa0) address=0xffff8880044f0fd8 value=0x200080 rm-118 [001] d.Z1. 6.472547: watch: (dentry_unlink_inode+0x14/0x110) address=0xffff8880044f0fd8 value=0x200080 rm-118 [001] d.Z1. 6.472551: watch: (dentry_unlink_inode+0x1e/0x110) address=0xffff8880044f0fd8 value=0x80 rm-118 [001] d.Z.. 6.472563: watch: (fast_dput+0x8d/0x120) address=0xffff8880044f0fd8 value=0x80 rm-118 [001] ...1. 6.472567: dentry_kill: (__dentry_kill+0x0/0x220) dentry=0xffff8880044f0fd8 sh-113 [004] ...2. 6.473049: dentry_kill: (__dentry_kill+0x0/0x220) dentry=0xffff888006e383a8 Thank you, --- Jinchao Wang (2): x86/hw_breakpoint: Unify breakpoint install/uninstall x86/hw_breakpoint: Add arch_reinstall_hw_breakpoint Masami Hiramatsu (Google) (8): tracing: wprobe: Add watchpoint probe event based on hardware breakpoint x86: hw_breakpoint: Add a kconfig to clarify when a breakpoint fires selftests: tracing: Add a basic testcase for wprobe selftests: tracing: Add syntax testcase for wprobe tracing: wprobe: Use a new seq_print_ip_sym_offset() wrapper HWBP: Add modify_wide_hw_breakpoint_local() API tracing: wprobe: Add wprobe event trigger selftests: ftrace: Add wprobe trigger testcase Documentation/trace/index.rst | 1 Documentation/trace/wprobetrace.rst | 158 +++ arch/Kconfig | 20 arch/x86/Kconfig | 2 arch/x86/include/asm/hw_breakpoint.h | 8 arch/x86/kernel/hw_breakpoint.c | 148 ++- include/linux/hw_breakpoint.h | 6 include/linux/trace_events.h | 3 kernel/events/hw_breakpoint.c | 39 + kernel/trace/Kconfig | 24 kernel/trace/Makefile | 1 kernel/trace/trace.c | 9 kernel/trace/trace.h | 5 kernel/trace/trace_probe.c | 22 kernel/trace/trace_probe.h | 8 kernel/trace/trace_wprobe.c | 1108 ++++++++++++++++++++ tools/testing/selftests/ftrace/config | 2 .../ftrace/test.d/dynevent/add_remove_wprobe.tc | 68 + .../test.d/dynevent/wprobes_syntax_errors.tc | 20 .../ftrace/test.d/trigger/trigger-wprobe.tc | 48 + 20 files changed, 1635 insertions(+), 65 deletions(-) create mode 100644 Documentation/trace/wprobetrace.rst create mode 100644 kernel/trace/trace_wprobe.c create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/add_remove_wprobe.tc create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/wprobes_syntax_errors.tc create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe.tc -- Masami Hiramatsu (Google)