From: Masami Hiramatsu <mhiramat@kernel.org>
To: Miroslav Benes <mbenes@suse.cz>
Cc: 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 00:42:25 +0900 [thread overview]
Message-ID: <20210311004225.77e844ff8170108bfb75b470@kernel.org> (raw)
In-Reply-To: <alpine.LSU.2.21.2103101258070.18547@pobox.suse.cz>
On Wed, 10 Mar 2021 15:21:01 +0100 (CET)
Miroslav Benes <mbenes@suse.cz> wrote:
> Hi Masami,
>
> > --- a/include/linux/kprobes.h
> > +++ b/include/linux/kprobes.h
> > @@ -205,15 +205,23 @@ extern void arch_prepare_kretprobe(struct kretprobe_instance *ri,
> > struct pt_regs *regs);
> > extern int arch_trampoline_kprobe(struct kprobe *p);
> >
> > +void kretprobe_trampoline(void);
> > +/*
> > + * Since some architecture uses structured function pointer,
> > + * use arch_deref_entry_point() to get real function address.
>
> s/arch_deref_entry_point/dereference_function_descriptor/ ?
Ah, I missed it. Thanks!
>
> > + */
> > +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.
But of course, it depends on the architecture. I'm not familiar
with the powerpc and s390, I need those maintainer's help...
Thank you,
--
Masami Hiramatsu <mhiramat@kernel.org>
next prev parent reply other threads:[~2021-03-10 15:43 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 [this message]
2021-03-11 13:37 ` Masami Hiramatsu
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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