+static void __kprobes setup_singlestep(struct kprobe *p, struct pt_regs *regs,
+ struct kprobe_ctlblk *kcb)
+{
+#if !defined(CONFIG_PREEMPT) || defined(CONFIG_PM)
+ if (p->ainsn.boostable == 1 && !p->post_handler) {
+ /* Boost up -- we can execute copied instructions directly */
+ reset_current_kprobe();
+ regs->ip = (unsigned long)p->ainsn.insn;
+ preempt_enable_no_resched();
+ return;
+ }
+#endif
+ prepare_singlestep(p, regs);
+ kcb->kprobe_status = KPROBE_HIT_SS;
+}
+
+/*
+ * We have reentered the kprobe_handler(), since another probe was hit while
+ * within the handler. We save the original kprobes variables and just single
+ * step on the instruction of the new probe without calling any user handlers.
+ */
+static int __kprobes reenter_kprobe(struct kprobe *p, struct pt_regs *regs,
+ struct kprobe_ctlblk *kcb)
+{
+ switch (kcb->kprobe_status) {
+ case KPROBE_HIT_SSDONE:
+#ifdef CONFIG_X86_64
+ /* TODO: Provide re-entrancy from post_kprobes_handler() and
+ * avoid exception stack corruption while single-stepping on
+ * the instruction of the new probe.
+ */
+ arch_disarm_kprobe(p);
+ regs->ip = (unsigned long)p->addr;
+ reset_current_kprobe();
+ preempt_enable_no_resched();
+ break;
+#endif
+ case KPROBE_HIT_ACTIVE:
+ save_previous_kprobe(kcb);
+ set_current_kprobe(p, regs, kcb);
+ kprobes_inc_nmissed_count(p);
+ prepare_singlestep(p, regs);
+ kcb->kprobe_status = KPROBE_REENTER;
+ break;
+ case KPROBE_HIT_SS:
+ if (p == kprobe_running()) {
+ regs->flags &= ~X86_EFLAGS_TF;
+ regs->flags |= kcb->kprobe_saved_flags;
+ return 0;
+ } else {
+ /* A probe has been hit in the codepath leading up
+ * to, or just after, single-stepping of a probed
+ * instruction. This entire codepath should strictly
+ * reside in .kprobes.text section. Raise a warning
+ * to highlight this peculiar case.
+ */
+ }
+ default:
+ /* impossible cases */
+ WARN_ON(1);
+ return 0;
+ }
+
+ return 1;
+}
+