Commit | Line | Data |
---|---|---|
5f97f7f9 HS |
1 | /* |
2 | * Kernel Probes (KProbes) | |
3 | * | |
4 | * Copyright (C) 2005-2006 Atmel Corporation | |
5 | * | |
6 | * Based on arch/ppc64/kernel/kprobes.c | |
7 | * Copyright (C) IBM Corporation, 2002, 2004 | |
8 | * | |
9 | * This program is free software; you can redistribute it and/or modify | |
10 | * it under the terms of the GNU General Public License version 2 as | |
11 | * published by the Free Software Foundation. | |
12 | */ | |
13 | ||
14 | #include <linux/kprobes.h> | |
15 | #include <linux/ptrace.h> | |
16 | ||
17 | #include <asm/cacheflush.h> | |
1eeb66a1 | 18 | #include <linux/kdebug.h> |
5f97f7f9 HS |
19 | #include <asm/ocd.h> |
20 | ||
21 | DEFINE_PER_CPU(struct kprobe *, current_kprobe); | |
22 | static unsigned long kprobe_status; | |
23 | static struct pt_regs jprobe_saved_regs; | |
24 | ||
f438d914 MH |
25 | struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}}; |
26 | ||
5f97f7f9 HS |
27 | int __kprobes arch_prepare_kprobe(struct kprobe *p) |
28 | { | |
29 | int ret = 0; | |
30 | ||
31 | if ((unsigned long)p->addr & 0x01) { | |
32 | printk("Attempt to register kprobe at an unaligned address\n"); | |
33 | ret = -EINVAL; | |
34 | } | |
35 | ||
36 | /* XXX: Might be a good idea to check if p->addr is a valid | |
37 | * kernel address as well... */ | |
38 | ||
39 | if (!ret) { | |
40 | pr_debug("copy kprobe at %p\n", p->addr); | |
41 | memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); | |
42 | p->opcode = *p->addr; | |
43 | } | |
44 | ||
45 | return ret; | |
46 | } | |
47 | ||
48 | void __kprobes arch_arm_kprobe(struct kprobe *p) | |
49 | { | |
50 | pr_debug("arming kprobe at %p\n", p->addr); | |
13b54a50 | 51 | ocd_enable(NULL); |
5f97f7f9 HS |
52 | *p->addr = BREAKPOINT_INSTRUCTION; |
53 | flush_icache_range((unsigned long)p->addr, | |
54 | (unsigned long)p->addr + sizeof(kprobe_opcode_t)); | |
55 | } | |
56 | ||
57 | void __kprobes arch_disarm_kprobe(struct kprobe *p) | |
58 | { | |
59 | pr_debug("disarming kprobe at %p\n", p->addr); | |
13b54a50 | 60 | ocd_disable(NULL); |
5f97f7f9 HS |
61 | *p->addr = p->opcode; |
62 | flush_icache_range((unsigned long)p->addr, | |
63 | (unsigned long)p->addr + sizeof(kprobe_opcode_t)); | |
64 | } | |
65 | ||
66 | static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) | |
67 | { | |
68 | unsigned long dc; | |
69 | ||
70 | pr_debug("preparing to singlestep over %p (PC=%08lx)\n", | |
71 | p->addr, regs->pc); | |
72 | ||
73 | BUG_ON(!(sysreg_read(SR) & SYSREG_BIT(SR_D))); | |
74 | ||
8dfe8f29 HS |
75 | dc = ocd_read(DC); |
76 | dc |= 1 << OCD_DC_SS_BIT; | |
77 | ocd_write(DC, dc); | |
5f97f7f9 HS |
78 | |
79 | /* | |
80 | * We must run the instruction from its original location | |
81 | * since it may actually reference PC. | |
82 | * | |
83 | * TODO: Do the instruction replacement directly in icache. | |
84 | */ | |
85 | *p->addr = p->opcode; | |
86 | flush_icache_range((unsigned long)p->addr, | |
87 | (unsigned long)p->addr + sizeof(kprobe_opcode_t)); | |
88 | } | |
89 | ||
90 | static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs) | |
91 | { | |
92 | unsigned long dc; | |
93 | ||
94 | pr_debug("resuming execution at PC=%08lx\n", regs->pc); | |
95 | ||
8dfe8f29 HS |
96 | dc = ocd_read(DC); |
97 | dc &= ~(1 << OCD_DC_SS_BIT); | |
98 | ocd_write(DC, dc); | |
5f97f7f9 HS |
99 | |
100 | *p->addr = BREAKPOINT_INSTRUCTION; | |
101 | flush_icache_range((unsigned long)p->addr, | |
102 | (unsigned long)p->addr + sizeof(kprobe_opcode_t)); | |
103 | } | |
104 | ||
105 | static void __kprobes set_current_kprobe(struct kprobe *p) | |
106 | { | |
107 | __get_cpu_var(current_kprobe) = p; | |
108 | } | |
109 | ||
110 | static int __kprobes kprobe_handler(struct pt_regs *regs) | |
111 | { | |
112 | struct kprobe *p; | |
113 | void *addr = (void *)regs->pc; | |
114 | int ret = 0; | |
115 | ||
6ea850b5 | 116 | pr_debug("kprobe_handler: kprobe_running=%p\n", |
5f97f7f9 HS |
117 | kprobe_running()); |
118 | ||
119 | /* | |
120 | * We don't want to be preempted for the entire | |
121 | * duration of kprobe processing | |
122 | */ | |
123 | preempt_disable(); | |
124 | ||
125 | /* Check that we're not recursing */ | |
126 | if (kprobe_running()) { | |
127 | p = get_kprobe(addr); | |
128 | if (p) { | |
129 | if (kprobe_status == KPROBE_HIT_SS) { | |
130 | printk("FIXME: kprobe hit while single-stepping!\n"); | |
131 | goto no_kprobe; | |
132 | } | |
133 | ||
134 | printk("FIXME: kprobe hit while handling another kprobe\n"); | |
135 | goto no_kprobe; | |
136 | } else { | |
137 | p = kprobe_running(); | |
138 | if (p->break_handler && p->break_handler(p, regs)) | |
139 | goto ss_probe; | |
140 | } | |
141 | /* If it's not ours, can't be delete race, (we hold lock). */ | |
142 | goto no_kprobe; | |
143 | } | |
144 | ||
145 | p = get_kprobe(addr); | |
146 | if (!p) | |
147 | goto no_kprobe; | |
148 | ||
149 | kprobe_status = KPROBE_HIT_ACTIVE; | |
150 | set_current_kprobe(p); | |
151 | if (p->pre_handler && p->pre_handler(p, regs)) | |
152 | /* handler has already set things up, so skip ss setup */ | |
153 | return 1; | |
154 | ||
155 | ss_probe: | |
156 | prepare_singlestep(p, regs); | |
157 | kprobe_status = KPROBE_HIT_SS; | |
158 | return 1; | |
159 | ||
160 | no_kprobe: | |
4d3eeeac | 161 | preempt_enable_no_resched(); |
5f97f7f9 HS |
162 | return ret; |
163 | } | |
164 | ||
165 | static int __kprobes post_kprobe_handler(struct pt_regs *regs) | |
166 | { | |
167 | struct kprobe *cur = kprobe_running(); | |
168 | ||
169 | pr_debug("post_kprobe_handler, cur=%p\n", cur); | |
170 | ||
171 | if (!cur) | |
172 | return 0; | |
173 | ||
174 | if (cur->post_handler) { | |
175 | kprobe_status = KPROBE_HIT_SSDONE; | |
176 | cur->post_handler(cur, regs, 0); | |
177 | } | |
178 | ||
179 | resume_execution(cur, regs); | |
180 | reset_current_kprobe(); | |
181 | preempt_enable_no_resched(); | |
182 | ||
183 | return 1; | |
184 | } | |
185 | ||
9caebec7 | 186 | int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
5f97f7f9 HS |
187 | { |
188 | struct kprobe *cur = kprobe_running(); | |
189 | ||
190 | pr_debug("kprobe_fault_handler: trapnr=%d\n", trapnr); | |
191 | ||
192 | if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) | |
193 | return 1; | |
194 | ||
195 | if (kprobe_status & KPROBE_HIT_SS) { | |
196 | resume_execution(cur, regs); | |
197 | preempt_enable_no_resched(); | |
198 | } | |
199 | return 0; | |
200 | } | |
201 | ||
202 | /* | |
203 | * Wrapper routine to for handling exceptions. | |
204 | */ | |
205 | int __kprobes kprobe_exceptions_notify(struct notifier_block *self, | |
206 | unsigned long val, void *data) | |
207 | { | |
208 | struct die_args *args = (struct die_args *)data; | |
209 | int ret = NOTIFY_DONE; | |
210 | ||
211 | pr_debug("kprobe_exceptions_notify: val=%lu, data=%p\n", | |
212 | val, data); | |
213 | ||
214 | switch (val) { | |
215 | case DIE_BREAKPOINT: | |
216 | if (kprobe_handler(args->regs)) | |
217 | ret = NOTIFY_STOP; | |
218 | break; | |
219 | case DIE_SSTEP: | |
220 | if (post_kprobe_handler(args->regs)) | |
221 | ret = NOTIFY_STOP; | |
222 | break; | |
5f97f7f9 HS |
223 | default: |
224 | break; | |
225 | } | |
226 | ||
227 | return ret; | |
228 | } | |
229 | ||
230 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) | |
231 | { | |
232 | struct jprobe *jp = container_of(p, struct jprobe, kp); | |
233 | ||
234 | memcpy(&jprobe_saved_regs, regs, sizeof(struct pt_regs)); | |
235 | ||
236 | /* | |
237 | * TODO: We should probably save some of the stack here as | |
238 | * well, since gcc may pass arguments on the stack for certain | |
239 | * functions (lots of arguments, large aggregates, varargs) | |
240 | */ | |
241 | ||
242 | /* setup return addr to the jprobe handler routine */ | |
243 | regs->pc = (unsigned long)jp->entry; | |
244 | return 1; | |
245 | } | |
246 | ||
247 | void __kprobes jprobe_return(void) | |
248 | { | |
249 | asm volatile("breakpoint" ::: "memory"); | |
250 | } | |
251 | ||
252 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) | |
253 | { | |
254 | /* | |
255 | * FIXME - we should ideally be validating that we got here 'cos | |
256 | * of the "trap" in jprobe_return() above, before restoring the | |
257 | * saved regs... | |
258 | */ | |
259 | memcpy(regs, &jprobe_saved_regs, sizeof(struct pt_regs)); | |
260 | return 1; | |
261 | } | |
262 | ||
263 | int __init arch_init_kprobes(void) | |
264 | { | |
5f97f7f9 HS |
265 | /* TODO: Register kretprobe trampoline */ |
266 | return 0; | |
267 | } |