1 // SPDX-License-Identifier: GPL-2.0
2
3 #include <linux/kprobes.h>
4
5 /* Ftrace callback handler for kprobes -- called under preepmt disabled */
kprobe_ftrace_handler(unsigned long ip,unsigned long parent_ip,struct ftrace_ops * ops,struct ftrace_regs * fregs)6 void 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 preempt_disable_notrace();
19 p = get_kprobe((kprobe_opcode_t *)ip);
20 if (unlikely(!p) || kprobe_disabled(p))
21 goto out;
22
23 regs = ftrace_get_regs(fregs);
24 kcb = get_kprobe_ctlblk();
25 if (kprobe_running()) {
26 kprobes_inc_nmissed_count(p);
27 } else {
28 unsigned long orig_ip = instruction_pointer(regs);
29
30 instruction_pointer_set(regs, ip);
31
32 __this_cpu_write(current_kprobe, p);
33 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
34 if (!p->pre_handler || !p->pre_handler(p, regs)) {
35 /*
36 * Emulate singlestep (and also recover regs->pc)
37 * as if there is a nop
38 */
39 instruction_pointer_set(regs,
40 (unsigned long)p->addr + MCOUNT_INSN_SIZE);
41 if (unlikely(p->post_handler)) {
42 kcb->kprobe_status = KPROBE_HIT_SSDONE;
43 p->post_handler(p, regs, 0);
44 }
45 instruction_pointer_set(regs, orig_ip);
46 }
47
48 /*
49 * If pre_handler returns !0, it changes regs->pc. We have to
50 * skip emulating post_handler.
51 */
52 __this_cpu_write(current_kprobe, NULL);
53 }
54 out:
55 preempt_enable_notrace();
56 ftrace_test_recursion_unlock(bit);
57 }
58 NOKPROBE_SYMBOL(kprobe_ftrace_handler);
59
arch_prepare_kprobe_ftrace(struct kprobe * p)60 int arch_prepare_kprobe_ftrace(struct kprobe *p)
61 {
62 p->ainsn.api.insn = NULL;
63 return 0;
64 }
65