1 files changed, 25 insertions, 9 deletions

diff --git a/arch/powerpc/kernel/kprobes-ftrace.c b/arch/powerpc/kernel/kprobes-ftrace.c
index 6c089d9757c9..7a1f99f1b47f 100644
--- a/arch/powerpc/kernel/kprobes-ftrace.c
+++ b/arch/powerpc/kernel/kprobes-ftrace.c
@@ -25,6 +25,21 @@
 #include <linux/preempt.h>
 #include <linux/ftrace.h>
 
+/*
+ * This is called from ftrace code after invoking registered handlers to
+ * disambiguate regs->nip changes done by jprobes and livepatch. We check if
+ * there is an active jprobe at the provided address (mcount location).
+ */
+int __is_active_jprobe(unsigned long addr)
+{
+	if (!preemptible()) {
+		struct kprobe *p = raw_cpu_read(current_kprobe);
+		return (p && (unsigned long)p->addr == addr) ? 1 : 0;
+	}
+
+	return 0;
+}
+
 static nokprobe_inline
 int __skip_singlestep(struct kprobe *p, struct pt_regs *regs,
 		      struct kprobe_ctlblk *kcb, unsigned long orig_nip)
@@ -60,11 +75,8 @@ void kprobe_ftrace_handler(unsigned long nip, unsigned long parent_nip,
 {
 	struct kprobe *p;
 	struct kprobe_ctlblk *kcb;
-	unsigned long flags;
 
-	/* Disable irq for emulating a breakpoint and avoiding preempt */
-	local_irq_save(flags);
-	hard_irq_disable();
+	preempt_disable();
 
 	p = get_kprobe((kprobe_opcode_t *)nip);
 	if (unlikely(!p) || kprobe_disabled(p))
@@ -86,13 +98,17 @@ void kprobe_ftrace_handler(unsigned long nip, unsigned long parent_nip,
 		kcb->kprobe_status = KPROBE_HIT_ACTIVE;
 		if (!p->pre_handler || !p->pre_handler(p, regs))
 			__skip_singlestep(p, regs, kcb, orig_nip);
-		/*
-		 * If pre_handler returns !0, it sets regs->nip and
-		 * resets current kprobe.
-		 */
+		else {
+			/*
+			 * If pre_handler returns !0, it sets regs->nip and
+			 * resets current kprobe. In this case, we should not
+			 * re-enable preemption.
+			 */
+			return;
+		}
 	}
 end:
-	local_irq_restore(flags);
+	preempt_enable_no_resched();
 }
 NOKPROBE_SYMBOL(kprobe_ftrace_handler);