From: Matt Wu <wuqiang.matt@bytedance.com>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Ingo Molnar <mingo@kernel.org>, X86 ML <x86@kernel.org>,
Daniel Xu <dxu@dxuuu.xyz>,
linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
kuba@kernel.org, mingo@redhat.com, ast@kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Borislav Petkov <bp@alien8.de>,
kernel-team@fb.com, yhs@fb.com, linux-ia64@vger.kernel.org,
Abhishek Sagar <sagar.abhishek@gmail.com>,
Andrii Nakryiko <andrii.nakryiko@gmail.com>
Subject: Re: [PATCH -tip v8 11/13] x86/unwind: Recover kretprobe trampoline entry
Date: Wed, 7 Jul 2021 22:42:47 +0800 [thread overview]
Message-ID: <3fc578e0-5b26-6067-d026-5b5d230d6720@bytedance.com> (raw)
In-Reply-To: <20210707222925.87ecc1391d0ab61db3d8398e@kernel.org>
On 2021/7/7 PM9:29, Masami Hiramatsu wrote:
> On Wed, 7 Jul 2021 19:45:30 +0900
> Masami Hiramatsu <mhiramat@kernel.org> wrote:
>
>> On Wed, 7 Jul 2021 12:20:57 +0200
>> Peter Zijlstra <peterz@infradead.org> wrote:
>>
>>> On Wed, Jul 07, 2021 at 07:15:10PM +0900, Masami Hiramatsu wrote:
>>>
>>>> I actually don't want to keep this feature because no one use it.
>>>> (only systemtap needs it?)
>>>
>>> Yeah, you mentioned systemtap, but since that's out-of-tree I don't
>>> care. Their problem.
>
> Yeah, maybe it is not hard to update.
>
>>>
>>>> Anyway, if we keep the idea-level compatibility (not code level),
>>>> what we need is 'void *data' in the struct kretprobe_instance.
>>>> User who needs it can allocate their own instance data for their
>>>> kretprobes when initialising it and sets in their entry handler.
>>>>
>>>> Then we can have a simple kretprobe_instance.
>>>
>>> When would you do the alloc? When installing the retprobe, but that
>>> might be inside the allocator, which means you can't call the allocator
>>> etc.. :-)
>>
>> Yes, so the user may need to allocate a pool right before register_kretprobe().
>> (whether per-kretprobe or per-task or global pool, that is user's choice.)
>>
>>>
>>> If we look at struct ftrace_ret_stack, it has a few fixed function
>>> fields. The calltime one is all that is needed for the kretprobe
>>> example code.
>>
>> kretprobe consumes 3 fields, a pointer to 'struct kretprobe' (which
>> stores callee function address in 'kretprobe::kp.addr'), a return
>> address and a frame pointer (*).
> > Oops, I forgot to add "void *data" for storing user data.
>
Should use "struct kretprobe_holder *rph", since "struct kretprobe" belongs
to 3rd-party module (which might be unloaded any time).
User's own pool might not work if the module can be unloaded. Better manage
the pool in kretprobe_holder, which needs no changes from user side.
next prev parent reply other threads:[~2021-07-07 14:43 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-18 7:05 [PATCH -tip v8 00/13] kprobes: Fix stacktrace with kretprobes on x86 Masami Hiramatsu
2021-06-18 7:05 ` [PATCH -tip v8 01/13] ia64: kprobes: Fix to pass correct trampoline address to the handler Masami Hiramatsu
2021-07-05 7:46 ` Ingo Molnar
2021-07-05 10:05 ` Masami Hiramatsu
2021-06-18 7:05 ` [PATCH -tip v8 02/13] kprobes: treewide: Replace arch_deref_entry_point() with dereference_symbol_descriptor() Masami Hiramatsu
2021-07-05 7:48 ` Ingo Molnar
2021-07-05 12:03 ` Masami Hiramatsu
2021-07-07 18:28 ` Andrii Nakryiko
2021-07-08 4:08 ` Masami Hiramatsu
2021-06-18 7:05 ` [PATCH -tip v8 03/13] kprobes: treewide: Remove trampoline_address from kretprobe_trampoline_handler() Masami Hiramatsu
2021-07-05 7:03 ` Ingo Molnar
2021-07-05 10:03 ` Masami Hiramatsu
2021-07-05 7:49 ` Ingo Molnar
2021-06-18 7:05 ` [PATCH -tip v8 04/13] kprobes: Add kretprobe_find_ret_addr() for searching return address Masami Hiramatsu
2021-07-05 7:42 ` Ingo Molnar
2021-07-05 14:11 ` Masami Hiramatsu
2021-06-18 7:06 ` [PATCH -tip v8 05/13] x86/kprobes: Add UNWIND_HINT_FUNC on kretprobe_trampoline code Masami Hiramatsu
2021-07-05 8:02 ` Ingo Molnar
2021-07-09 15:31 ` Masami Hiramatsu
2021-07-10 1:41 ` Masami Hiramatsu
2021-07-10 19:01 ` Josh Poimboeuf
2021-07-10 19:24 ` [PATCH 1/2] objtool: Add frame-pointer-specific function ignore Josh Poimboeuf
2021-07-11 1:16 ` Masami Hiramatsu
2021-07-29 2:31 ` Masami Hiramatsu
2021-07-10 19:25 ` [PATCH 2/2] objtool: Ignore unwind hints for ignored functions Josh Poimboeuf
2021-07-11 2:07 ` Masami Hiramatsu
2021-06-18 7:06 ` [PATCH -tip v8 06/13] ARC: Add instruction_pointer_set() API Masami Hiramatsu
2021-06-18 7:06 ` [PATCH -tip v8 07/13] ia64: " Masami Hiramatsu
2021-06-18 7:06 ` [PATCH -tip v8 08/13] arm: kprobes: Make a space for regs->ARM_pc at kretprobe_trampoline Masami Hiramatsu
2021-07-05 8:04 ` Ingo Molnar
2021-07-05 14:40 ` Masami Hiramatsu
2021-06-18 7:06 ` [PATCH -tip v8 09/13] kprobes: Enable stacktrace from pt_regs in kretprobe handler Masami Hiramatsu
2021-06-18 14:04 ` Josh Poimboeuf
2021-06-18 7:06 ` [PATCH -tip v8 10/13] x86/kprobes: Push a fake return address at kretprobe_trampoline Masami Hiramatsu
2021-07-05 8:17 ` Ingo Molnar
2021-07-09 14:55 ` Masami Hiramatsu
2021-06-18 7:07 ` [PATCH -tip v8 11/13] x86/unwind: Recover kretprobe trampoline entry Masami Hiramatsu
2021-07-05 11:36 ` Peter Zijlstra
2021-07-05 15:42 ` Masami Hiramatsu
2021-07-06 7:55 ` Peter Zijlstra
2021-07-06 15:11 ` Steven Rostedt
2021-07-07 8:20 ` Peter Zijlstra
2021-07-07 8:36 ` Peter Zijlstra
2021-07-07 10:15 ` Masami Hiramatsu
2021-07-07 10:20 ` Peter Zijlstra
2021-07-07 10:45 ` Masami Hiramatsu
2021-07-07 13:29 ` Masami Hiramatsu
2021-07-07 14:42 ` Matt Wu [this message]
2021-07-11 14:09 ` Masami Hiramatsu
2021-07-11 15:28 ` Matt Wu
2021-07-12 4:57 ` Masami Hiramatsu
2021-06-18 7:07 ` [PATCH -tip v8 12/13] tracing: Show kretprobe unknown indicator only for kretprobe_trampoline Masami Hiramatsu
2021-06-18 7:07 ` [PATCH -tip v8 13/13] x86/kprobes: Fixup return address in generic trampoline handler Masami Hiramatsu
2021-07-05 8:34 ` Ingo Molnar
2021-07-06 12:57 ` Masami Hiramatsu
2021-06-18 17:44 ` [PATCH -tip v8 00/13] kprobes: Fix stacktrace with kretprobes on x86 Andrii Nakryiko
2021-06-28 13:50 ` Masami Hiramatsu
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