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

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 38cf7a7..7847e5c 100644 (file)
--- 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