1 // SPDX-License-Identifier: GPL-2.0
2
3 #include <linux/kprobes.h>
4
arch_check_ftrace_location(struct kprobe * p)5 int arch_check_ftrace_location(struct kprobe *p)
6 {
7 if (ftrace_location((unsigned long)p->addr))
8 p->flags |= KPROBE_FLAG_FTRACE;
9 return 0;
10 }
11
12 /* 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)13 void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
14 struct ftrace_ops *ops, struct ftrace_regs *fregs)
15 {
16 int bit;
17 bool lr_saver = false;
18 struct kprobe *p;
19 struct kprobe_ctlblk *kcb;
20 struct pt_regs *regs;
21
22 bit = ftrace_test_recursion_trylock(ip, parent_ip);
23 if (bit < 0)
24 return;
25
26 regs = ftrace_get_regs(fregs);
27 preempt_disable_notrace();
28 p = get_kprobe((kprobe_opcode_t *)ip);
29 if (!p) {
30 p = get_kprobe((kprobe_opcode_t *)(ip - MCOUNT_INSN_SIZE));
31 if (unlikely(!p) || kprobe_disabled(p))
32 goto out;
33 lr_saver = true;
34 }
35
36 kcb = get_kprobe_ctlblk();
37 if (kprobe_running()) {
38 kprobes_inc_nmissed_count(p);
39 } else {
40 unsigned long orig_ip = instruction_pointer(regs);
41
42 if (lr_saver)
43 ip -= MCOUNT_INSN_SIZE;
44 instruction_pointer_set(regs, ip);
45 __this_cpu_write(current_kprobe, p);
46 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
47 if (!p->pre_handler || !p->pre_handler(p, regs)) {
48 /*
49 * Emulate singlestep (and also recover regs->pc)
50 * as if there is a nop
51 */
52 instruction_pointer_set(regs,
53 (unsigned long)p->addr + MCOUNT_INSN_SIZE);
54 if (unlikely(p->post_handler)) {
55 kcb->kprobe_status = KPROBE_HIT_SSDONE;
56 p->post_handler(p, regs, 0);
57 }
58 instruction_pointer_set(regs, orig_ip);
59 }
60 /*
61 * If pre_handler returns !0, it changes regs->pc. We have to
62 * skip emulating post_handler.
63 */
64 __this_cpu_write(current_kprobe, NULL);
65 }
66 out:
67 preempt_enable_notrace();
68 ftrace_test_recursion_unlock(bit);
69 }
70 NOKPROBE_SYMBOL(kprobe_ftrace_handler);
71
arch_prepare_kprobe_ftrace(struct kprobe * p)72 int arch_prepare_kprobe_ftrace(struct kprobe *p)
73 {
74 p->ainsn.api.insn = NULL;
75 return 0;
76 }
77