From: Peter Zijlstra <peterz@infradead.org>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>, Andy Lutomirski <luto@kernel.org>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Oleg Nesterov <oleg@redhat.com>,
"H . Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>, X86 ML <x86@kernel.org>,
Borislav Petkov <bp@alien8.de>,
dwmw@amazon.co.uk, linux-kernel@vger.kernel.org
Subject: Re: [PATCH -tip] kprobes/x86: Use preempt_enable() in optimized_callback()
Date: Sun, 21 Oct 2018 22:42:29 +0200 [thread overview]
Message-ID: <20181021204229.GI4931@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <154002887331.7627.10194920925792947001.stgit@devbox>
On Sat, Oct 20, 2018 at 06:47:53PM +0900, Masami Hiramatsu wrote:
> Since commit a19b2e3d7839 ("kprobes/x86: Remove IRQ disabling from
> ftrace-based/optimized kprobes”) removes local_irq_save/restore()
> from optimized_callback(), the handler does not protected against
> reschedule interrupt. If it is able to be preempted (rescheduled)
> by such interrupt, we don't need to use _no_resched macro.
must not.
> Let's use preempt_enable() instead.
>
> Fixes: a19b2e3d7839 ("kprobes/x86: Remove IRQ disabling from ftrace-based/optimized kprobes”)
> Link: https://lkml.kernel.org/r/37CB98C2-AF9B-475B-8B2D-7B414DC491F3@vmware.com
> Reported-by: Nadav Amit <namit@vmware.com>
> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> ---
> arch/x86/kernel/kprobes/opt.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
> index eaf02f2e7300..40b16b270656 100644
> --- a/arch/x86/kernel/kprobes/opt.c
> +++ b/arch/x86/kernel/kprobes/opt.c
> @@ -179,7 +179,7 @@ optimized_callback(struct optimized_kprobe *op, struct pt_regs *regs)
> opt_pre_handler(&op->kp, regs);
> __this_cpu_write(current_kprobe, NULL);
> }
> - preempt_enable_no_resched();
> + preempt_enable();
> }
Indeed,
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
next prev parent reply other threads:[~2018-10-21 20:42 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-20 9:47 [PATCH -tip] kprobes/x86: Use preempt_enable() in optimized_callback() Masami Hiramatsu
2018-10-21 20:42 ` Peter Zijlstra [this message]
2018-10-22 1:33 ` [tip:perf/core] " tip-bot for Masami Hiramatsu
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