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 if (unlikely(kprobe_ftrace_disabled))
15 return;
16
17 bit = ftrace_test_recursion_trylock(ip, parent_ip);
18 if (bit < 0)
19 return;
20
21 p = get_kprobe((kprobe_opcode_t *)ip);
22 if (unlikely(!p) || kprobe_disabled(p))
23 goto out;
24
25 regs = ftrace_get_regs(fregs);
26 kcb = get_kprobe_ctlblk();
27 if (kprobe_running()) {
28 kprobes_inc_nmissed_count(p);
29 } else {
30 unsigned long orig_ip = instruction_pointer(regs);
31
32 instruction_pointer_set(regs, ip);
33
34 __this_cpu_write(current_kprobe, p);
35 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
36 if (!p->pre_handler || !p->pre_handler(p, regs)) {
37 /*
38 * Emulate singlestep (and also recover regs->pc)
39 * as if there is a nop
40 */
41 instruction_pointer_set(regs,
42 (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);
46 }
47 instruction_pointer_set(regs, orig_ip);
48 }
49
50 /*
51 * If pre_handler returns !0, it changes regs->pc. We have to
52 * skip emulating post_handler.
53 */
54 __this_cpu_write(current_kprobe, NULL);
55 }
56 out:
57 ftrace_test_recursion_unlock(bit);
58 }
59 NOKPROBE_SYMBOL(kprobe_ftrace_handler);
60
arch_prepare_kprobe_ftrace(struct kprobe * p)61 int arch_prepare_kprobe_ftrace(struct kprobe *p)
62 {
63 p->ainsn.api.insn = NULL;
64 return 0;
65 }
66