1 files changed, 67 insertions, 0 deletions

diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
index e2f751efb7b1..57916c0d3cf6 100644
--- a/arch/x86/kernel/kprobes.c
+++ b/arch/x86/kernel/kprobes.c
@@ -541,6 +541,23 @@ reenter_kprobe(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb
         return 1;
 }
 
+#ifdef KPROBES_CAN_USE_FTRACE
+static void __kprobes skip_singlestep(struct kprobe *p, struct pt_regs *regs,
+                                      struct kprobe_ctlblk *kcb)
+{
+        /*
+         * Emulate singlestep (and also recover regs->ip)
+         * as if there is a 5byte nop
+         */
+        regs->ip = (unsigned long)p->addr + MCOUNT_INSN_SIZE;
+        if (unlikely(p->post_handler)) {
+                kcb->kprobe_status = KPROBE_HIT_SSDONE;
+                p->post_handler(p, regs, 0);
+        }
+        __this_cpu_write(current_kprobe, NULL);
+}
+#endif
+
 /*
  * Interrupts are disabled on entry as trap3 is an interrupt gate and they
  * remain disabled throughout this function.
@@ -599,6 +616,12 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
         } else if (kprobe_running()) {
                 p = __this_cpu_read(current_kprobe);
                 if (p->break_handler && p->break_handler(p, regs)) {
+#ifdef KPROBES_CAN_USE_FTRACE
+                        if (kprobe_ftrace(p)) {
+                                skip_singlestep(p, regs, kcb);
+                                return 1;
+                        }
+#endif
                         setup_singlestep(p, regs, kcb, 0);
                         return 1;
                 }
@@ -1052,6 +1075,50 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
         return 0;
 }
 
+#ifdef KPROBES_CAN_USE_FTRACE
+/* Ftrace callback handler for kprobes */
+void __kprobes kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
+                                     struct ftrace_ops *ops, struct pt_regs *regs)
+{
+        struct kprobe *p;
+        struct kprobe_ctlblk *kcb;
+        unsigned long flags;
+
+        /* Disable irq for emulating a breakpoint and avoiding preempt */
+        local_irq_save(flags);
+
+        p = get_kprobe((kprobe_opcode_t *)ip);
+        if (unlikely(!p) || kprobe_disabled(p))
+                goto end;
+
+        kcb = get_kprobe_ctlblk();
+        if (kprobe_running()) {
+                kprobes_inc_nmissed_count(p);
+        } else {
+                /* Kprobe handler expects regs->ip = ip + 1 as breakpoint hit */
+                regs->ip = ip + sizeof(kprobe_opcode_t);
+
+                __this_cpu_write(current_kprobe, p);
+                kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+                if (!p->pre_handler || !p->pre_handler(p, regs))
+                        skip_singlestep(p, regs, kcb);
+                /*
+                 * If pre_handler returns !0, it sets regs->ip and
+                 * resets current kprobe.
+                 */
+        }
+end:
+        local_irq_restore(flags);
+}
+
+int __kprobes arch_prepare_kprobe_ftrace(struct kprobe *p)
+{
+        p->ainsn.insn = NULL;
+        p->ainsn.boostable = -1;
+        return 0;
+}
+#endif
+
 int __init arch_init_kprobes(void)
 {
         return arch_init_optprobes();