Re: [PATCH v3 1/4] rethook: use preempt_{disable, enable}_notrace in rethook_trampoline_handler

Ze Gao
2023-05-18T02:41:05Z

Great, thanks!

Regards,
Ze

On Wed, May 17, 2023 at 7:59 PM Masami Hiramatsu <mhiramat@kernel.org> wrote:
>
> Hi Ze Gao,
>
> On Wed, 17 May 2023 11:45:06 +0800
> Ze Gao <zegao2021@gmail.com> wrote:
>
> > This patch replaces preempt_{disable, enable} with its corresponding
> > notrace version in rethook_trampoline_handler so no worries about stack
> > recursion or overflow introduced by preempt_count_{add, sub} under
> > fprobe + rethook context.
> >
> > Fixes: 54ecbe6f1ed5 ("rethook: Add a generic return hook")
> > Signed-off-by: Ze Gao <zegao@tencent.com>
> > Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> > Cc: <stable@vger.kernel.org>
> > Link: https://lore.kernel.org/linux-trace-kernel/20230516071830.8190-2-zegao@tencent.com
>
> Note that you don't need to add Link tag of the previous version for each patch.
> I'll add it when I pick it :)
>
> Thank you,
>
> > ---
> > kernel/trace/rethook.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/kernel/trace/rethook.c b/kernel/trace/rethook.c
> > index 32c3dfdb4d6a..60f6cb2b486b 100644
> > --- a/kernel/trace/rethook.c
> > +++ b/kernel/trace/rethook.c
> > @@ -288,7 +288,7 @@ unsigned long rethook_trampoline_handler(struct pt_regs *regs,
> > * These loops must be protected from rethook_free_rcu() because those
> > * are accessing 'rhn->rethook'.
> > */
> > - preempt_disable();
> > + preempt_disable_notrace();
> >
> > /*
> > * Run the handler on the shadow stack. Do not unlink the list here because
> > @@ -321,7 +321,7 @@ unsigned long rethook_trampoline_handler(struct pt_regs *regs,
> > first = first->next;
> > rethook_recycle(rhn);
> > }
> > - preempt_enable();
> > + preempt_enable_notrace();
> >
> > return correct_ret_addr;
> > }
> > --
> > 2.40.1
> >
>
>
> --
> Masami Hiramatsu (Google) <mhiramat@kernel.org>