Commit | Line | Data |
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e7dbfe34 MH |
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 | ||
f684199f | 26 | #include "common.h" |
e7dbfe34 MH |
27 | |
28 | static 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 | ||
44 | int __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 */ | |
54 | void __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 | } | |
84 | end: | |
85 | local_irq_restore(flags); | |
86 | } | |
87 | ||
88 | int __kprobes arch_prepare_kprobe_ftrace(struct kprobe *p) | |
89 | { | |
90 | p->ainsn.insn = NULL; | |
91 | p->ainsn.boostable = -1; | |
92 | return 0; | |
93 | } |