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 disabed */
kprobe_ftrace_handler(unsigned long ip,unsigned long parent_ip,struct ftrace_ops * ops,struct pt_regs * regs)13 void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
14 struct ftrace_ops *ops, struct pt_regs *regs)
15 {
16 bool lr_saver = false;
17 struct kprobe *p;
18 struct kprobe_ctlblk *kcb;
19
20 /* Preempt is disabled by ftrace */
21 p = get_kprobe((kprobe_opcode_t *)ip);
22 if (!p) {
23 p = get_kprobe((kprobe_opcode_t *)(ip - MCOUNT_INSN_SIZE));
24 if (unlikely(!p) || kprobe_disabled(p))
25 return;
26 lr_saver = true;
27 }
28
29 kcb = get_kprobe_ctlblk();
30 if (kprobe_running()) {
31 kprobes_inc_nmissed_count(p);
32 } else {
33 unsigned long orig_ip = instruction_pointer(regs);
34
35 if (lr_saver)
36 ip -= MCOUNT_INSN_SIZE;
37 instruction_pointer_set(regs, ip);
38 __this_cpu_write(current_kprobe, p);
39 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
40 if (!p->pre_handler || !p->pre_handler(p, regs)) {
41 /*
42 * Emulate singlestep (and also recover regs->pc)
43 * as if there is a nop
44 */
45 instruction_pointer_set(regs,
46 (unsigned long)p->addr + MCOUNT_INSN_SIZE);
47 if (unlikely(p->post_handler)) {
48 kcb->kprobe_status = KPROBE_HIT_SSDONE;
49 p->post_handler(p, regs, 0);
50 }
51 instruction_pointer_set(regs, orig_ip);
52 }
53 /*
54 * If pre_handler returns !0, it changes regs->pc. We have to
55 * skip emulating post_handler.
56 */
57 __this_cpu_write(current_kprobe, NULL);
58 }
59 }
60 NOKPROBE_SYMBOL(kprobe_ftrace_handler);
61
arch_prepare_kprobe_ftrace(struct kprobe * p)62 int arch_prepare_kprobe_ftrace(struct kprobe *p)
63 {
64 p->ainsn.api.insn = NULL;
65 return 0;
66 }
67