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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
29void __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}
45
46int skip_singlestep(struct kprobe *p, struct pt_regs *regs,
47 struct kprobe_ctlblk *kcb)
48{
49 if (kprobe_ftrace(p)) {
50 __skip_singlestep(p, regs, kcb, 0);
51 preempt_enable_no_resched();
52 return 1;
53 }
54 return 0;
55}
56NOKPROBE_SYMBOL(skip_singlestep);
57
58/* Ftrace callback handler for kprobes -- called under preepmt disabed */
59void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
60 struct ftrace_ops *ops, struct pt_regs *regs)
61{
62 struct kprobe *p;
63 struct kprobe_ctlblk *kcb;
64
65 /* Preempt is disabled by ftrace */
66 p = get_kprobe((kprobe_opcode_t *)ip);
67 if (unlikely(!p) || kprobe_disabled(p))
68 return;
69
70 kcb = get_kprobe_ctlblk();
71 if (kprobe_running()) {
72 kprobes_inc_nmissed_count(p);
73 } else {
74 unsigned long orig_ip = regs->ip;
75 /* Kprobe handler expects regs->ip = ip + 1 as breakpoint hit */
76 regs->ip = ip + sizeof(kprobe_opcode_t);
77
78 /* To emulate trap based kprobes, preempt_disable here */
79 preempt_disable();
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 preempt_enable_no_resched();
85 }
86 /*
87 * If pre_handler returns !0, it sets regs->ip and
88 * resets current kprobe, and keep preempt count +1.
89 */
90 }
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 = false;
98 return 0;
99}
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 int __skip_singlestep(struct kprobe *p, struct pt_regs *regs,
29 struct kprobe_ctlblk *kcb)
30{
31 /*
32 * Emulate singlestep (and also recover regs->ip)
33 * as if there is a 5byte nop
34 */
35 regs->ip = (unsigned long)p->addr + MCOUNT_INSN_SIZE;
36 if (unlikely(p->post_handler)) {
37 kcb->kprobe_status = KPROBE_HIT_SSDONE;
38 p->post_handler(p, regs, 0);
39 }
40 __this_cpu_write(current_kprobe, NULL);
41 return 1;
42}
43
44int __kprobes skip_singlestep(struct kprobe *p, struct pt_regs *regs,
45 struct kprobe_ctlblk *kcb)
46{
47 if (kprobe_ftrace(p))
48 return __skip_singlestep(p, regs, kcb);
49 else
50 return 0;
51}
52
53/* Ftrace callback handler for kprobes */
54void __kprobes kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
55 struct ftrace_ops *ops, struct pt_regs *regs)
56{
57 struct kprobe *p;
58 struct kprobe_ctlblk *kcb;
59 unsigned long flags;
60
61 /* Disable irq for emulating a breakpoint and avoiding preempt */
62 local_irq_save(flags);
63
64 p = get_kprobe((kprobe_opcode_t *)ip);
65 if (unlikely(!p) || kprobe_disabled(p))
66 goto end;
67
68 kcb = get_kprobe_ctlblk();
69 if (kprobe_running()) {
70 kprobes_inc_nmissed_count(p);
71 } else {
72 /* Kprobe handler expects regs->ip = ip + 1 as breakpoint hit */
73 regs->ip = ip + sizeof(kprobe_opcode_t);
74
75 __this_cpu_write(current_kprobe, p);
76 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
77 if (!p->pre_handler || !p->pre_handler(p, regs))
78 __skip_singlestep(p, regs, kcb);
79 /*
80 * If pre_handler returns !0, it sets regs->ip and
81 * resets current kprobe.
82 */
83 }
84end:
85 local_irq_restore(flags);
86}
87
88int __kprobes arch_prepare_kprobe_ftrace(struct kprobe *p)
89{
90 p->ainsn.insn = NULL;
91 p->ainsn.boostable = -1;
92 return 0;
93}