[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20210324160143.wd43zribpeop2czn@treble>
Date: Wed, 24 Mar 2021 11:01:43 -0500
From: Josh Poimboeuf <jpoimboe@...hat.com>
To: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>,
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,
Abhishek Sagar <sagar.abhishek@...il.com>
Subject: Re: [PATCH -tip v4 10/12] x86/kprobes: Push a fake return address at
kretprobe_trampoline
On Wed, Mar 24, 2021 at 10:40:58AM +0900, Masami Hiramatsu wrote:
> On Tue, 23 Mar 2021 23:30:07 +0100
> Peter Zijlstra <peterz@...radead.org> wrote:
>
> > On Mon, Mar 22, 2021 at 03:41:40PM +0900, Masami Hiramatsu wrote:
> > > ".global kretprobe_trampoline\n"
> > > ".type kretprobe_trampoline, @function\n"
> > > "kretprobe_trampoline:\n"
> > > #ifdef CONFIG_X86_64
> >
> > So what happens if we get an NMI here? That is, after the RET but before
> > the push? Then our IP points into the trampoline but we've not done that
> > push yet.
>
> Not only NMI, but also interrupts can happen. There is no cli/sti here.
>
> Anyway, thanks for pointing!
> I think in UNWIND_HINT_TYPE_REGS and UNWIND_HINT_TYPE_REGS_PARTIAL cases
> ORC unwinder also has to check the state->ip and if it is kretprobe_trampoline,
> it should be recovered.
> What about this?
I think the REGS and REGS_PARTIAL cases can also be affected by function
graph tracing. So should they use the generic unwind_recover_ret_addr()
instead of unwind_recover_kretprobe()?
--
Josh
Powered by blists - more mailing lists