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authorLinus Torvalds <torvalds@linux-foundation.org>2016-06-25 06:49:32 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-06-25 06:49:32 -0700
commit9a949a98596c45763299158b9018f3491e3cbf99 (patch)
treefd7943339a39997d2906f1951ee2565e175be3c7
parent57801c1b817128cbb3a4dc45e6a1e0e31a227a19 (diff)
parentdcfc47248d3f7d28df6f531e6426b933de94370d (diff)
downloadlinux-9a949a98596c45763299158b9018f3491e3cbf99.tar.gz
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
-rw-r--r--arch/x86/kernel/kprobes/core.c12
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