From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Sat, 25 Jun 2016 13:49:32 +0000 (-0700)
Subject: Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel... 
X-Git-Tag: v4.7-rc5~5
X-Git-Url: http://git.cascardo.eti.br/?a=commitdiff_plain;h=9a949a98596c45763299158b9018f3491e3cbf99;hp=57801c1b817128cbb3a4dc45e6a1e0e31a227a19;p=cascardo%2Flinux.git

Merge branch 'perf-urgent-for-linus' of git://git./linux/kernel/git/tip/tip

Pull x86 kprobe fix from Thomas Gleixner:
 "A single fix clearing the TF bit when a fault is single stepped"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  kprobes/x86: Clear TF bit in fault on single-stepping
---

diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 38cf7a741250..7847e5c0e0b5 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -961,7 +961,19 @@ int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 		 * normal page fault.
 		 */
 		regs->ip = (unsigned long)cur->addr;
+		/*
+		 * Trap flag (TF) has been set here because this fault
+		 * happened where the single stepping will be done.
+		 * So clear it by resetting the current kprobe:
+		 */
+		regs->flags &= ~X86_EFLAGS_TF;
+
+		/*
+		 * If the TF flag was set before the kprobe hit,
+		 * don't touch it:
+		 */
 		regs->flags |= kcb->kprobe_old_flags;
+
 		if (kcb->kprobe_status == KPROBE_REENTER)
 			restore_previous_kprobe(kcb);
 		else