Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/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

1 files changed, 12 insertions, 0 deletions

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