From: Peter Zijlstra <peterz@infradead.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Masami Hiramatsu <mhiramat@kernel.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>,
wuqiang.matt@bytedance.com
Subject: Re: [PATCH -tip v8 11/13] x86/unwind: Recover kretprobe trampoline entry
Date: Wed, 7 Jul 2021 10:36:28 +0200 [thread overview]
Message-ID: <YOVnjCxOORB4epjr@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <YOVj2VoyrcOvJfEB@hirez.programming.kicks-ass.net>
On Wed, Jul 07, 2021 at 10:20:41AM +0200, Peter Zijlstra wrote:
> > > Steve, can you clarify the ftrace side here? Afaict return_to_handler()
> > > is similarly affected.
> >
> > I'm not exactly sure what the issue is. As Masami stated, kretprobe
> > uses a ret to return to the calling function, but ftrace uses a jmp.
>
> I'll have to re-read the ftrace bits, but from the top of my head you
> cannot do an indirect jump and preserve all registers at the same time,
> so a return stub must use jump from stack aka. ret.
Hmm... there's callee clobbered regs ofcourse, which don't need to be
preserved. And that's exactly what ftrace seems to be doing, and I don't
think there's any reason why kretprobe cannot do the same. Lemme try.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Masami Hiramatsu <mhiramat@kernel.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>,
wuqiang.matt@bytedance.com
Subject: Re: [PATCH -tip v8 11/13] x86/unwind: Recover kretprobe trampoline entry
Date: Wed, 07 Jul 2021 08:36:28 +0000 [thread overview]
Message-ID: <YOVnjCxOORB4epjr@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <YOVj2VoyrcOvJfEB@hirez.programming.kicks-ass.net>
On Wed, Jul 07, 2021 at 10:20:41AM +0200, Peter Zijlstra wrote:
> > > Steve, can you clarify the ftrace side here? Afaict return_to_handler()
> > > is similarly affected.
> >
> > I'm not exactly sure what the issue is. As Masami stated, kretprobe
> > uses a ret to return to the calling function, but ftrace uses a jmp.
>
> I'll have to re-read the ftrace bits, but from the top of my head you
> cannot do an indirect jump and preserve all registers at the same time,
> so a return stub must use jump from stack aka. ret.
Hmm... there's callee clobbered regs ofcourse, which don't need to be
preserved. And that's exactly what ftrace seems to be doing, and I don't
think there's any reason why kretprobe cannot do the same. Lemme try.
next prev parent reply other threads:[~2021-07-07 8:36 UTC|newest]
Thread overview: 114+ 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 ` 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
2021-06-18 7:05 ` Masami Hiramatsu
2021-07-05 7:46 ` Ingo Molnar
2021-07-05 7:46 ` Ingo Molnar
2021-07-05 10:05 ` Masami Hiramatsu
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
2021-06-18 7:05 ` [PATCH -tip v8 02/13] kprobes: treewide: Replace arch_deref_entry_point() with dereference_symbol_de Masami Hiramatsu
2021-07-05 7:48 ` [PATCH -tip v8 02/13] kprobes: treewide: Replace arch_deref_entry_point() with dereference_symbol_descriptor() Ingo Molnar
2021-07-05 7:48 ` [PATCH -tip v8 02/13] kprobes: treewide: Replace arch_deref_entry_point() with dereference_symbo Ingo Molnar
2021-07-05 12:03 ` [PATCH -tip v8 02/13] kprobes: treewide: Replace arch_deref_entry_point() with dereference_symbol_descriptor() Masami Hiramatsu
2021-07-05 12:03 ` [PATCH -tip v8 02/13] kprobes: treewide: Replace arch_deref_entry_point() with dereference_symbo Masami Hiramatsu
2021-07-07 18:28 ` [PATCH -tip v8 02/13] kprobes: treewide: Replace arch_deref_entry_point() with dereference_symbol_descriptor() Andrii Nakryiko
2021-07-07 18:28 ` [PATCH -tip v8 02/13] kprobes: treewide: Replace arch_deref_entry_point() with dereference_symbo Andrii Nakryiko
2021-07-08 4:08 ` [PATCH -tip v8 02/13] kprobes: treewide: Replace arch_deref_entry_point() with dereference_symbol_descriptor() Masami Hiramatsu
2021-07-08 4:08 ` [PATCH -tip v8 02/13] kprobes: treewide: Replace arch_deref_entry_point() with dereference_symbo Masami Hiramatsu
2021-06-18 7:05 ` [PATCH -tip v8 03/13] kprobes: treewide: Remove trampoline_address from kretprobe_trampoline_handler() 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 ` [PATCH -tip v8 03/13] kprobes: treewide: Remove trampoline_address from kretprobe_trampoline_handler() Ingo Molnar
2021-07-05 7:03 ` [PATCH -tip v8 03/13] kprobes: treewide: Remove trampoline_address from kretprobe_trampoline_han Ingo Molnar
2021-07-05 10:03 ` [PATCH -tip v8 03/13] kprobes: treewide: Remove trampoline_address from kretprobe_trampoline_handler() Masami Hiramatsu
2021-07-05 10:03 ` [PATCH -tip v8 03/13] kprobes: treewide: Remove trampoline_address from kretprobe_trampoline_han Masami Hiramatsu
2021-07-05 7:49 ` [PATCH -tip v8 03/13] kprobes: treewide: Remove trampoline_address from kretprobe_trampoline_handler() Ingo Molnar
2021-07-05 7:49 ` [PATCH -tip v8 03/13] kprobes: treewide: Remove trampoline_address from kretprobe_trampoline_han Ingo Molnar
2021-06-18 7:05 ` [PATCH -tip v8 04/13] kprobes: Add kretprobe_find_ret_addr() for searching return address Masami Hiramatsu
2021-06-18 7:05 ` Masami Hiramatsu
2021-07-05 7:42 ` Ingo Molnar
2021-07-05 7:42 ` Ingo Molnar
2021-07-05 14:11 ` Masami Hiramatsu
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
2021-06-18 7:06 ` Masami Hiramatsu
2021-07-05 8:02 ` Ingo Molnar
2021-07-05 8:02 ` Ingo Molnar
2021-07-09 15:31 ` Masami Hiramatsu
2021-07-09 15:31 ` Masami Hiramatsu
2021-07-10 1:41 ` Masami Hiramatsu
2021-07-10 1:41 ` Masami Hiramatsu
2021-07-10 19:01 ` Josh Poimboeuf
2021-07-10 19:01 ` Josh Poimboeuf
2021-07-10 19:24 ` [PATCH 1/2] objtool: Add frame-pointer-specific function ignore Josh Poimboeuf
2021-07-10 19:24 ` Josh Poimboeuf
2021-07-11 1:16 ` Masami Hiramatsu
2021-07-11 1:16 ` Masami Hiramatsu
2021-07-29 2:31 ` 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
2021-07-10 19:25 ` Josh Poimboeuf
2021-07-11 2:07 ` Masami Hiramatsu
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 ` Masami Hiramatsu
2021-06-18 7:06 ` [PATCH -tip v8 07/13] ia64: " Masami Hiramatsu
2021-06-18 7:06 ` 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
2021-06-18 7:06 ` Masami Hiramatsu
2021-07-05 8:04 ` Ingo Molnar
2021-07-05 8:04 ` Ingo Molnar
2021-07-05 14:40 ` Masami Hiramatsu
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 7:06 ` Masami Hiramatsu
2021-06-18 14:04 ` Josh Poimboeuf
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
2021-06-18 7:06 ` Masami Hiramatsu
2021-07-05 8:17 ` Ingo Molnar
2021-07-05 8:17 ` Ingo Molnar
2021-07-09 14:55 ` Masami Hiramatsu
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
2021-06-18 7:07 ` Masami Hiramatsu
2021-07-05 11:36 ` Peter Zijlstra
2021-07-05 11:36 ` Peter Zijlstra
2021-07-05 15:42 ` Masami Hiramatsu
2021-07-05 15:42 ` Masami Hiramatsu
2021-07-06 7:55 ` Peter Zijlstra
2021-07-06 7:55 ` Peter Zijlstra
2021-07-06 15:11 ` Steven Rostedt
2021-07-06 15:11 ` Steven Rostedt
2021-07-07 8:20 ` Peter Zijlstra
2021-07-07 8:20 ` Peter Zijlstra
2021-07-07 8:36 ` Peter Zijlstra [this message]
2021-07-07 8:36 ` Peter Zijlstra
2021-07-07 10:15 ` Masami Hiramatsu
2021-07-07 10:15 ` Masami Hiramatsu
2021-07-07 10:20 ` Peter Zijlstra
2021-07-07 10:20 ` Peter Zijlstra
2021-07-07 10:45 ` Masami Hiramatsu
2021-07-07 10:45 ` Masami Hiramatsu
2021-07-07 13:29 ` Masami Hiramatsu
2021-07-07 13:29 ` Masami Hiramatsu
2021-07-07 14:42 ` Matt Wu
2021-07-07 14:42 ` Matt Wu
2021-07-11 14:09 ` Masami Hiramatsu
2021-07-11 14:09 ` Masami Hiramatsu
2021-07-11 15:28 ` Matt Wu
2021-07-11 15:28 ` Matt Wu
2021-07-12 4:57 ` Masami Hiramatsu
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 ` Masami Hiramatsu
2021-06-18 7:07 ` [PATCH -tip v8 13/13] x86/kprobes: Fixup return address in generic trampoline handler Masami Hiramatsu
2021-06-18 7:07 ` Masami Hiramatsu
2021-07-05 8:34 ` Ingo Molnar
2021-07-05 8:34 ` Ingo Molnar
2021-07-06 12:57 ` Masami Hiramatsu
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
2021-06-18 17:44 ` Andrii Nakryiko
2021-06-28 13:50 ` Masami Hiramatsu
2021-06-28 13:50 ` Masami Hiramatsu
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