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Message-ID: <20210321174855.oqqtvgb2xwyk4klf@treble>
Date: Sun, 21 Mar 2021 12:50:04 -0500
From: Josh Poimboeuf <jpoimboe@...hat.com>
To: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Steven Rostedt <rostedt@...dmis.org>,
Ingo Molnar <mingo@...nel.org>, X86 ML <x86@...nel.org>,
Daniel Xu <dxu@...uu.xyz>, linux-kernel@...r.kernel.org,
bpf@...r.kernel.org, kuba@...nel.org, mingo@...hat.com,
ast@...nel.org, tglx@...utronix.de, kernel-team@...com, yhs@...com,
linux-ia64@...r.kernel.org
Subject: Re: [PATCH -tip v3 05/11] x86/kprobes: Add UNWIND_HINT_FUNC on
kretprobe_trampoline code
On Sat, Mar 20, 2021 at 09:16:16PM +0900, Masami Hiramatsu wrote:
> On Fri, 19 Mar 2021 21:22:39 +0900
> Masami Hiramatsu <mhiramat@...nel.org> wrote:
>
> > From: Josh Poimboeuf <jpoimboe@...hat.com>
> >
> > Add UNWIND_HINT_FUNC on kretporbe_trampoline code so that ORC
> > information is generated on the kretprobe_trampoline correctly.
> >
>
> Test bot also found a new warning for this.
>
> > >> arch/x86/kernel/kprobes/core.o: warning: objtool: kretprobe_trampoline()+0x25: call without frame pointer save/setup
>
> With CONFIG_FRAME_POINTER=y.
>
> Of course this can be fixed with additional "push %bp; mov %sp, %bp" before calling
> trampoline_handler. But actually we know that this function has a bit special
> stack frame too.
>
> Can I recover STACK_FRAME_NON_STANDARD(kretprobe_trampoline) when CONFIG_FRAME_POINTER=y ?
Yes, that's what I'd recommend.
--
Josh
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