1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Dynamic Ftrace based Kprobes Optimization
5 * Copyright (C) Hitachi Ltd., 2012
7 #include <linux/kprobes.h>
8 #include <linux/ptrace.h>
9 #include <linux/hardirq.h>
10 #include <linux/preempt.h>
11 #include <linux/ftrace.h>
15 /* Ftrace callback handler for kprobes -- called under preepmt disabed */
16 void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
17 struct ftrace_ops *ops, struct pt_regs *regs)
20 struct kprobe_ctlblk *kcb;
22 /* Preempt is disabled by ftrace */
23 p = get_kprobe((kprobe_opcode_t *)ip);
24 if (unlikely(!p) || kprobe_disabled(p))
27 kcb = get_kprobe_ctlblk();
28 if (kprobe_running()) {
29 kprobes_inc_nmissed_count(p);
31 unsigned long orig_ip = regs->ip;
32 /* Kprobe handler expects regs->ip = ip + 1 as breakpoint hit */
33 regs->ip = ip + sizeof(kprobe_opcode_t);
35 __this_cpu_write(current_kprobe, p);
36 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
37 if (!p->pre_handler || !p->pre_handler(p, regs)) {
39 * Emulate singlestep (and also recover regs->ip)
40 * as if there is a 5byte nop
42 regs->ip = (unsigned long)p->addr + MCOUNT_INSN_SIZE;
43 if (unlikely(p->post_handler)) {
44 kcb->kprobe_status = KPROBE_HIT_SSDONE;
45 p->post_handler(p, regs, 0);
50 * If pre_handler returns !0, it changes regs->ip. We have to
51 * skip emulating post_handler.
53 __this_cpu_write(current_kprobe, NULL);
56 NOKPROBE_SYMBOL(kprobe_ftrace_handler);
58 int arch_prepare_kprobe_ftrace(struct kprobe *p)
61 p->ainsn.boostable = false;