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Commit b7e4138c authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Greg Kroah-Hartman
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kprobes/x86: Use preempt_enable() in optimized_callback() 



commit 2e62024c265aa69315ed02835623740030435380 upstream.

The following commit:

  a19b2e3d ("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: default avatarNadav Amit <namit@vmware.com>
Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Acked-by: default avatarPeter 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: a19b2e3d ("kprobes/x86: Remove IRQ disabling from ftrace-based/optimized kprobes”)
Link: http://lkml.kernel.org/r/154002887331.7627.10194920925792947001.stgit@devbox


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 96f81d51

arch/x86/kernel/kprobes/opt.c

+1 −1
Original line number Diff line number Diff line
@@ -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);