1// SPDX-License-Identifier: GPL-2.0-or-later
 2/*
 3 * Dynamic Ftrace based Kprobes Optimization
 4 *
 5 * Copyright (C) Hitachi Ltd., 2012
 6 */
 7#include <linux/kprobes.h>
 8#include <linux/ptrace.h>
 9#include <linux/hardirq.h>
10#include <linux/preempt.h>
11#include <linux/ftrace.h>
12#include <asm/text-patching.h>
13
14#include "common.h"
15
16/* Ftrace callback handler for kprobes -- called under preempt disabled */
17void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
18			   struct ftrace_ops *ops, struct ftrace_regs *fregs)
19{
20	struct pt_regs *regs = ftrace_get_regs(fregs);
21	struct kprobe *p;
22	struct kprobe_ctlblk *kcb;
23	int bit;
24
25	if (unlikely(kprobe_ftrace_disabled))
26		return;
27
28	bit = ftrace_test_recursion_trylock(ip, parent_ip);
29	if (bit < 0)
30		return;
31
32	p = get_kprobe((kprobe_opcode_t *)ip);
33	if (unlikely(!p) || kprobe_disabled(p))
34		goto out;
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		/* Kprobe handler expects regs->ip = ip + 1 as breakpoint hit */
43		instruction_pointer_set(regs, ip + INT3_INSN_SIZE);
44
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			if (unlikely(p->post_handler)) {
49				/*
50				 * Emulate singlestep (and also recover regs->ip)
51				 * as if there is a 5byte nop
52				 */
53				instruction_pointer_set(regs, ip + MCOUNT_INSN_SIZE);
54				kcb->kprobe_status = KPROBE_HIT_SSDONE;
55				p->post_handler(p, regs, 0);
56			}
57			/* Recover IP address */
58			instruction_pointer_set(regs, orig_ip);
59		}
60		/*
61		 * If pre_handler returns !0, it changes regs->ip. We have to
62		 * skip emulating post_handler.
63		 */
64		__this_cpu_write(current_kprobe, NULL);
65	}
66out:
67	ftrace_test_recursion_unlock(bit);
68}
69NOKPROBE_SYMBOL(kprobe_ftrace_handler);
70
71int arch_prepare_kprobe_ftrace(struct kprobe *p)
72{
73	p->ainsn.insn = NULL;
74	p->ainsn.boostable = false;
75	return 0;
76}

 1// SPDX-License-Identifier: GPL-2.0-or-later
 2/*
 3 * Dynamic Ftrace based Kprobes Optimization
 4 *
 5 * Copyright (C) Hitachi Ltd., 2012
 6 */
 7#include <linux/kprobes.h>
 8#include <linux/ptrace.h>
 9#include <linux/hardirq.h>
10#include <linux/preempt.h>
11#include <linux/ftrace.h>
 
12
13#include "common.h"
14
15/* Ftrace callback handler for kprobes -- called under preempt disabled */
16void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
17			   struct ftrace_ops *ops, struct ftrace_regs *fregs)
18{
19	struct pt_regs *regs = ftrace_get_regs(fregs);
20	struct kprobe *p;
21	struct kprobe_ctlblk *kcb;
22	int bit;
23
 
 
 
24	bit = ftrace_test_recursion_trylock(ip, parent_ip);
25	if (bit < 0)
26		return;
27
28	p = get_kprobe((kprobe_opcode_t *)ip);
29	if (unlikely(!p) || kprobe_disabled(p))
30		goto out;
31
32	kcb = get_kprobe_ctlblk();
33	if (kprobe_running()) {
34		kprobes_inc_nmissed_count(p);
35	} else {
36		unsigned long orig_ip = regs->ip;
 
37		/* Kprobe handler expects regs->ip = ip + 1 as breakpoint hit */
38		regs->ip = ip + sizeof(kprobe_opcode_t);
39
40		__this_cpu_write(current_kprobe, p);
41		kcb->kprobe_status = KPROBE_HIT_ACTIVE;
42		if (!p->pre_handler || !p->pre_handler(p, regs)) {
43			/*
44			 * Emulate singlestep (and also recover regs->ip)
45			 * as if there is a 5byte nop
46			 */
47			regs->ip = (unsigned long)p->addr + MCOUNT_INSN_SIZE;
48			if (unlikely(p->post_handler)) {
 
 
 
 
 
49				kcb->kprobe_status = KPROBE_HIT_SSDONE;
50				p->post_handler(p, regs, 0);
51			}
52			regs->ip = orig_ip;
 
53		}
54		/*
55		 * If pre_handler returns !0, it changes regs->ip. We have to
56		 * skip emulating post_handler.
57		 */
58		__this_cpu_write(current_kprobe, NULL);
59	}
60out:
61	ftrace_test_recursion_unlock(bit);
62}
63NOKPROBE_SYMBOL(kprobe_ftrace_handler);
64
65int arch_prepare_kprobe_ftrace(struct kprobe *p)
66{
67	p->ainsn.insn = NULL;
68	p->ainsn.boostable = false;
69	return 0;
70}