* [PATCH -tip] kprobes/x86: Use preempt_enable() in optimized_callback()
@ 2018-10-20 9:47 Masami Hiramatsu
2018-10-21 20:42 ` Peter Zijlstra
2018-10-22 1:33 ` [tip:perf/core] " tip-bot for Masami Hiramatsu
0 siblings, 2 replies; 3+ messages in thread
From: Masami Hiramatsu @ 2018-10-20 9:47 UTC (permalink / raw)
To: Ingo Molnar
Cc: Andy Lutomirski, Alexei Starovoitov, Oleg Nesterov,
Peter Zijlstra, H . Peter Anvin, Thomas Gleixner, X86 ML,
Borislav Petkov, dwmw, Masami Hiramatsu, linux-kernel
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.
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();
}
NOKPROBE_SYMBOL(optimized_callback);
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH -tip] kprobes/x86: Use preempt_enable() in optimized_callback()
2018-10-20 9:47 [PATCH -tip] kprobes/x86: Use preempt_enable() in optimized_callback() Masami Hiramatsu
@ 2018-10-21 20:42 ` Peter Zijlstra
2018-10-22 1:33 ` [tip:perf/core] " tip-bot for Masami Hiramatsu
1 sibling, 0 replies; 3+ messages in thread
From: Peter Zijlstra @ 2018-10-21 20:42 UTC (permalink / raw)
To: Masami Hiramatsu
Cc: Ingo Molnar, Andy Lutomirski, Alexei Starovoitov, Oleg Nesterov,
H . Peter Anvin, Thomas Gleixner, X86 ML, Borislav Petkov, dwmw,
linux-kernel
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>
^ permalink raw reply [flat|nested] 3+ messages in thread
* [tip:perf/core] kprobes/x86: Use preempt_enable() in optimized_callback()
2018-10-20 9:47 [PATCH -tip] kprobes/x86: Use preempt_enable() in optimized_callback() Masami Hiramatsu
2018-10-21 20:42 ` Peter Zijlstra
@ 2018-10-22 1:33 ` tip-bot for Masami Hiramatsu
1 sibling, 0 replies; 3+ messages in thread
From: tip-bot for Masami Hiramatsu @ 2018-10-22 1:33 UTC (permalink / raw)
To: linux-tip-commits
Cc: tglx, oleg, torvalds, namit, mingo, alexei.starovoitov, hpa,
mhiramat, peterz, linux-kernel, luto, stable, bp
Commit-ID: 2e62024c265aa69315ed02835623740030435380
Gitweb: https://git.kernel.org/tip/2e62024c265aa69315ed02835623740030435380
Author: Masami Hiramatsu <mhiramat@kernel.org>
AuthorDate: Sat, 20 Oct 2018 18:47:53 +0900
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 22 Oct 2018 03:31:01 +0200
kprobes/x86: Use preempt_enable() in optimized_callback()
The following commit:
a19b2e3d7839 ("kprobes/x86: Remove IRQ disabling from ftrace-based/optimized kprobes”)
removed local_irq_save/restore() from optimized_callback(), the handler
might be interrupted by the rescheduling interrupt and might be
rescheduled - so we must not use the preempt_enable_no_resched() macro.
Use preempt_enable() instead, to not lose preemption events.
[ mingo: Improved the changelog. ]
Reported-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dwmw@amazon.co.uk
Fixes: a19b2e3d7839 ("kprobes/x86: Remove IRQ disabling from ftrace-based/optimized kprobes”)
Link: http://lkml.kernel.org/r/154002887331.7627.10194920925792947001.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@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();
}
NOKPROBE_SYMBOL(optimized_callback);
^ permalink raw reply related [flat|nested] 3+ messages in thread
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2018-10-20 9:47 [PATCH -tip] kprobes/x86: Use preempt_enable() in optimized_callback() Masami Hiramatsu
2018-10-21 20:42 ` Peter Zijlstra
2018-10-22 1:33 ` [tip:perf/core] " tip-bot for Masami Hiramatsu
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