1// SPDX-License-Identifier: GPL-2.0
2
3#include <linux/kprobes.h>
4
5/* Ftrace callback handler for kprobes -- called under preepmt disabled */
6void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
7			   struct ftrace_ops *ops, struct ftrace_regs *fregs)
8{
9	struct kprobe *p;
10	struct pt_regs *regs;
11	struct kprobe_ctlblk *kcb;
12	int bit;
13
14	bit = ftrace_test_recursion_trylock(ip, parent_ip);
15	if (bit < 0)
16		return;
17
18	p = get_kprobe((kprobe_opcode_t *)ip);
19	if (unlikely(!p) || kprobe_disabled(p))
20		goto out;
21
22	regs = ftrace_get_regs(fregs);
23	kcb = get_kprobe_ctlblk();
24	if (kprobe_running()) {
25		kprobes_inc_nmissed_count(p);
26	} else {
27		unsigned long orig_ip = instruction_pointer(regs);
28
29		instruction_pointer_set(regs, ip);
30
31		__this_cpu_write(current_kprobe, p);
32		kcb->kprobe_status = KPROBE_HIT_ACTIVE;
33		if (!p->pre_handler || !p->pre_handler(p, regs)) {
34			/*
35			 * Emulate singlestep (and also recover regs->pc)
36			 * as if there is a nop
37			 */
38			instruction_pointer_set(regs,
39				(unsigned long)p->addr + MCOUNT_INSN_SIZE);
40			if (unlikely(p->post_handler)) {
41				kcb->kprobe_status = KPROBE_HIT_SSDONE;
42				p->post_handler(p, regs, 0);
43			}
44			instruction_pointer_set(regs, orig_ip);
45		}
46
47		/*
48		 * If pre_handler returns !0, it changes regs->pc. We have to
49		 * skip emulating post_handler.
50		 */
51		__this_cpu_write(current_kprobe, NULL);
52	}
53out:
54	ftrace_test_recursion_unlock(bit);
55}
56NOKPROBE_SYMBOL(kprobe_ftrace_handler);
57
58int arch_prepare_kprobe_ftrace(struct kprobe *p)
59{
60	p->ainsn.api.insn = NULL;
61	return 0;
62}
63