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 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 }
53 out:
54 ftrace_test_recursion_unlock(bit);
55 }
56 NOKPROBE_SYMBOL(kprobe_ftrace_handler);
57
arch_prepare_kprobe_ftrace(struct kprobe * p)58 int arch_prepare_kprobe_ftrace(struct kprobe *p)
59 {
60 p->ainsn.api.insn = NULL;
61 return 0;
62 }
63