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From: Masami Hiramatsu <mhiramat@kernel.org>
To: Ingo Molnar <mingo@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>,
	Alexei Starovoitov <alexei.starovoitov@gmail.com>,
	Oleg Nesterov <oleg@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	"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, Masami Hiramatsu <mhiramat@kernel.org>,
	linux-kernel@vger.kernel.org
Subject: [PATCH -tip] kprobes/x86: Use preempt_enable() in optimized_callback()
Date: Sat, 20 Oct 2018 18:47:53 +0900
Message-ID: <154002887331.7627.10194920925792947001.stgit@devbox> (raw)

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);
 


             reply index

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-20  9:47 Masami Hiramatsu [this message]
2018-10-21 20:42 ` Peter Zijlstra
2018-10-22  1:33 ` [tip:perf/core] " tip-bot for Masami Hiramatsu

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