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}

 
 1/*
 2 * Dynamic Ftrace based Kprobes Optimization
 3 *
 4 * This program is free software; you can redistribute it and/or modify
 5 * it under the terms of the GNU General Public License as published by
 6 * the Free Software Foundation; either version 2 of the License, or
 7 * (at your option) any later version.
 8 *
 9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17 *
18 * Copyright (C) Hitachi Ltd., 2012
19 */
20#include <linux/kprobes.h>
21#include <linux/ptrace.h>
22#include <linux/hardirq.h>
23#include <linux/preempt.h>
24#include <linux/ftrace.h>
25
26#include "common.h"
27
28static nokprobe_inline
29int __skip_singlestep(struct kprobe *p, struct pt_regs *regs,
30		      struct kprobe_ctlblk *kcb, unsigned long orig_ip)
31{
32	/*
33	 * Emulate singlestep (and also recover regs->ip)
34	 * as if there is a 5byte nop
35	 */
36	regs->ip = (unsigned long)p->addr + MCOUNT_INSN_SIZE;
37	if (unlikely(p->post_handler)) {
38		kcb->kprobe_status = KPROBE_HIT_SSDONE;
39		p->post_handler(p, regs, 0);
40	}
41	__this_cpu_write(current_kprobe, NULL);
42	if (orig_ip)
43		regs->ip = orig_ip;
44	return 1;
45}
46
47int skip_singlestep(struct kprobe *p, struct pt_regs *regs,
48		    struct kprobe_ctlblk *kcb)
49{
50	if (kprobe_ftrace(p))
51		return __skip_singlestep(p, regs, kcb, 0);
52	else
53		return 0;
54}
55NOKPROBE_SYMBOL(skip_singlestep);
56
57/* Ftrace callback handler for kprobes */
58void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
59			   struct ftrace_ops *ops, struct pt_regs *regs)
60{
 
61	struct kprobe *p;
62	struct kprobe_ctlblk *kcb;
63	unsigned long flags;
64
65	/* Disable irq for emulating a breakpoint and avoiding preempt */
66	local_irq_save(flags);
 
67
68	p = get_kprobe((kprobe_opcode_t *)ip);
69	if (unlikely(!p) || kprobe_disabled(p))
70		goto end;
71
72	kcb = get_kprobe_ctlblk();
73	if (kprobe_running()) {
74		kprobes_inc_nmissed_count(p);
75	} else {
76		unsigned long orig_ip = regs->ip;
77		/* Kprobe handler expects regs->ip = ip + 1 as breakpoint hit */
78		regs->ip = ip + sizeof(kprobe_opcode_t);
79
80		__this_cpu_write(current_kprobe, p);
81		kcb->kprobe_status = KPROBE_HIT_ACTIVE;
82		if (!p->pre_handler || !p->pre_handler(p, regs))
83			__skip_singlestep(p, regs, kcb, orig_ip);
 
 
 
 
 
 
 
 
 
 
84		/*
85		 * If pre_handler returns !0, it sets regs->ip and
86		 * resets current kprobe.
87		 */
 
88	}
89end:
90	local_irq_restore(flags);
91}
92NOKPROBE_SYMBOL(kprobe_ftrace_handler);
93
94int arch_prepare_kprobe_ftrace(struct kprobe *p)
95{
96	p->ainsn.insn = NULL;
97	p->ainsn.boostable = -1;
98	return 0;
99}