From: Masami Hiramatsu <mhiramat@kernel.org>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Miroslav Benes <mbenes@suse.cz>,
Steven Rostedt <rostedt@goodmis.org>,
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,
tglx@linutronix.de, kernel-team@fb.com, yhs@fb.com
Subject: Re: [PATCH -tip 3/5] kprobes: treewide: Remove trampoline_address from kretprobe_trampoline_handler()
Date: Thu, 11 Mar 2021 22:37:20 +0900 [thread overview]
Message-ID: <20210311223720.dcdf5bdd65831028b8775dd7@kernel.org> (raw)
In-Reply-To: <20210311004225.77e844ff8170108bfb75b470@kernel.org>
Hi Miroslav,
On Thu, 11 Mar 2021 00:42:25 +0900
Masami Hiramatsu <mhiramat@kernel.org> wrote:
> > > + */
> > > +static nokprobe_inline void *kretprobe_trampoline_addr(void)
> > > +{
> > > + return dereference_function_descriptor(kretprobe_trampoline);
> > > +}
> > > +
> >
> > Would it make sense to use this in s390 and powerpc reliable unwinders?
> >
> > Both
> >
> > arch/s390/kernel/stacktrace.c:arch_stack_walk_reliable()
> > arch/powerpc/kernel/stacktrace.c:__save_stack_trace_tsk_reliable()
> >
> > have
> >
> > if (state.ip == (unsigned long)kretprobe_trampoline)
> > return -EINVAL;
> >
> > which you wanted to hide previously if I am not mistaken.
>
> I think, if "ip" means "instruction pointer", it should point
> the real instruction address, which is dereferenced from function
> descriptor. So using kretprobe_trampoline_addr() is good.
Ah, sorry I misunderstood the question.
Yes, the per-arch stacktrace implementation must be fixed afterwards.
It is reliable or not depends on the actual unwinder implementation,
for example, on x86, frame-pointer based unwinder can unwind kretprobe,
but ORC based one doesn't (and discussing with Josh how to solve it)
Anyway since it strongly depends on the architecture, I would like to
leave those for each architecture stacktrace maitainer in this series.
Thank you,
--
Masami Hiramatsu <mhiramat@kernel.org>
next prev parent reply other threads:[~2021-03-11 13:38 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-05 15:38 [PATCH -tip 0/5] kprobes: Fix stacktrace in kretprobes Masami Hiramatsu
2021-03-05 15:39 ` [PATCH -tip 1/5] ia64: kprobes: Fix to pass correct trampoline address to the handler Masami Hiramatsu
2021-03-05 15:39 ` [PATCH -tip 2/5] kprobes: treewide: Replace arch_deref_entry_point() with dereference_function_descriptor() Masami Hiramatsu
2021-03-05 15:39 ` [PATCH -tip 3/5] kprobes: treewide: Remove trampoline_address from kretprobe_trampoline_handler() Masami Hiramatsu
2021-03-10 14:21 ` Miroslav Benes
2021-03-10 15:42 ` Masami Hiramatsu
2021-03-11 13:37 ` Masami Hiramatsu [this message]
2021-03-05 15:39 ` [PATCH -tip 4/5] kprobes: stacktrace: Recover the address changed by kretprobe Masami Hiramatsu
2021-03-05 15:39 ` [PATCH -tip 5/5] tracing: Remove kretprobe unknown indicator from stacktrace Masami Hiramatsu
2021-03-05 15:44 ` Steven Rostedt
2021-03-05 19:16 ` [PATCH -tip 0/5] kprobes: Fix stacktrace in kretprobes Daniel Xu
2021-03-06 1:13 ` Masami Hiramatsu
2021-03-07 21:23 ` Daniel Xu
2021-03-08 2:52 ` Masami Hiramatsu
2021-03-08 13:05 ` Masami Hiramatsu
2021-03-09 1:19 ` Josh Poimboeuf
2021-03-10 9:57 ` Masami Hiramatsu
2021-03-10 15:08 ` Josh Poimboeuf
2021-03-10 15:55 ` Masami Hiramatsu
2021-03-10 18:31 ` Josh Poimboeuf
2021-03-11 0:20 ` Masami Hiramatsu
2021-03-11 1:06 ` Josh Poimboeuf
2021-03-11 1:54 ` Masami Hiramatsu
2021-03-11 16:51 ` Josh Poimboeuf
2021-03-12 3:22 ` Masami Hiramatsu
2021-03-10 22:46 ` Daniel Xu
2021-03-09 21:34 ` Daniel Xu
2021-03-10 10:50 ` Masami Hiramatsu
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