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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 | ||
25 | int __kprobes arch_prepare_kprobe(struct kprobe *p) | |
26 | { | |
27 | int ret = 0; | |
28 | ||
29 | if ((unsigned long)p->addr & 0x01) { | |
30 | printk("Attempt to register kprobe at an unaligned address\n"); | |
31 | ret = -EINVAL; | |
32 | } | |
33 | ||
34 | /* XXX: Might be a good idea to check if p->addr is a valid | |
35 | * kernel address as well... */ | |
36 | ||
37 | if (!ret) { | |
38 | pr_debug("copy kprobe at %p\n", p->addr); | |
39 | memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); | |
40 | p->opcode = *p->addr; | |
41 | } | |
42 | ||
43 | return ret; | |
44 | } | |
45 | ||
46 | void __kprobes arch_arm_kprobe(struct kprobe *p) | |
47 | { | |
48 | pr_debug("arming kprobe at %p\n", p->addr); | |
49 | *p->addr = BREAKPOINT_INSTRUCTION; | |
50 | flush_icache_range((unsigned long)p->addr, | |
51 | (unsigned long)p->addr + sizeof(kprobe_opcode_t)); | |
52 | } | |
53 | ||
54 | void __kprobes arch_disarm_kprobe(struct kprobe *p) | |
55 | { | |
56 | pr_debug("disarming kprobe at %p\n", p->addr); | |
57 | *p->addr = p->opcode; | |
58 | flush_icache_range((unsigned long)p->addr, | |
59 | (unsigned long)p->addr + sizeof(kprobe_opcode_t)); | |
60 | } | |
61 | ||
62 | static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) | |
63 | { | |
64 | unsigned long dc; | |
65 | ||
66 | pr_debug("preparing to singlestep over %p (PC=%08lx)\n", | |
67 | p->addr, regs->pc); | |
68 | ||
69 | BUG_ON(!(sysreg_read(SR) & SYSREG_BIT(SR_D))); | |
70 | ||
71 | dc = __mfdr(DBGREG_DC); | |
72 | dc |= DC_SS; | |
73 | __mtdr(DBGREG_DC, dc); | |
74 | ||
75 | /* | |
76 | * We must run the instruction from its original location | |
77 | * since it may actually reference PC. | |
78 | * | |
79 | * TODO: Do the instruction replacement directly in icache. | |
80 | */ | |
81 | *p->addr = p->opcode; | |
82 | flush_icache_range((unsigned long)p->addr, | |
83 | (unsigned long)p->addr + sizeof(kprobe_opcode_t)); | |
84 | } | |
85 | ||
86 | static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs) | |
87 | { | |
88 | unsigned long dc; | |
89 | ||
90 | pr_debug("resuming execution at PC=%08lx\n", regs->pc); | |
91 | ||
92 | dc = __mfdr(DBGREG_DC); | |
93 | dc &= ~DC_SS; | |
94 | __mtdr(DBGREG_DC, dc); | |
95 | ||
96 | *p->addr = BREAKPOINT_INSTRUCTION; | |
97 | flush_icache_range((unsigned long)p->addr, | |
98 | (unsigned long)p->addr + sizeof(kprobe_opcode_t)); | |
99 | } | |
100 | ||
101 | static void __kprobes set_current_kprobe(struct kprobe *p) | |
102 | { | |
103 | __get_cpu_var(current_kprobe) = p; | |
104 | } | |
105 | ||
106 | static int __kprobes kprobe_handler(struct pt_regs *regs) | |
107 | { | |
108 | struct kprobe *p; | |
109 | void *addr = (void *)regs->pc; | |
110 | int ret = 0; | |
111 | ||
6ea850b5 | 112 | pr_debug("kprobe_handler: kprobe_running=%p\n", |
5f97f7f9 HS |
113 | kprobe_running()); |
114 | ||
115 | /* | |
116 | * We don't want to be preempted for the entire | |
117 | * duration of kprobe processing | |
118 | */ | |
119 | preempt_disable(); | |
120 | ||
121 | /* Check that we're not recursing */ | |
122 | if (kprobe_running()) { | |
123 | p = get_kprobe(addr); | |
124 | if (p) { | |
125 | if (kprobe_status == KPROBE_HIT_SS) { | |
126 | printk("FIXME: kprobe hit while single-stepping!\n"); | |
127 | goto no_kprobe; | |
128 | } | |
129 | ||
130 | printk("FIXME: kprobe hit while handling another kprobe\n"); | |
131 | goto no_kprobe; | |
132 | } else { | |
133 | p = kprobe_running(); | |
134 | if (p->break_handler && p->break_handler(p, regs)) | |
135 | goto ss_probe; | |
136 | } | |
137 | /* If it's not ours, can't be delete race, (we hold lock). */ | |
138 | goto no_kprobe; | |
139 | } | |
140 | ||
141 | p = get_kprobe(addr); | |
142 | if (!p) | |
143 | goto no_kprobe; | |
144 | ||
145 | kprobe_status = KPROBE_HIT_ACTIVE; | |
146 | set_current_kprobe(p); | |
147 | if (p->pre_handler && p->pre_handler(p, regs)) | |
148 | /* handler has already set things up, so skip ss setup */ | |
149 | return 1; | |
150 | ||
151 | ss_probe: | |
152 | prepare_singlestep(p, regs); | |
153 | kprobe_status = KPROBE_HIT_SS; | |
154 | return 1; | |
155 | ||
156 | no_kprobe: | |
4d3eeeac | 157 | preempt_enable_no_resched(); |
5f97f7f9 HS |
158 | return ret; |
159 | } | |
160 | ||
161 | static int __kprobes post_kprobe_handler(struct pt_regs *regs) | |
162 | { | |
163 | struct kprobe *cur = kprobe_running(); | |
164 | ||
165 | pr_debug("post_kprobe_handler, cur=%p\n", cur); | |
166 | ||
167 | if (!cur) | |
168 | return 0; | |
169 | ||
170 | if (cur->post_handler) { | |
171 | kprobe_status = KPROBE_HIT_SSDONE; | |
172 | cur->post_handler(cur, regs, 0); | |
173 | } | |
174 | ||
175 | resume_execution(cur, regs); | |
176 | reset_current_kprobe(); | |
177 | preempt_enable_no_resched(); | |
178 | ||
179 | return 1; | |
180 | } | |
181 | ||
182 | static int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) | |
183 | { | |
184 | struct kprobe *cur = kprobe_running(); | |
185 | ||
186 | pr_debug("kprobe_fault_handler: trapnr=%d\n", trapnr); | |
187 | ||
188 | if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) | |
189 | return 1; | |
190 | ||
191 | if (kprobe_status & KPROBE_HIT_SS) { | |
192 | resume_execution(cur, regs); | |
193 | preempt_enable_no_resched(); | |
194 | } | |
195 | return 0; | |
196 | } | |
197 | ||
198 | /* | |
199 | * Wrapper routine to for handling exceptions. | |
200 | */ | |
201 | int __kprobes kprobe_exceptions_notify(struct notifier_block *self, | |
202 | unsigned long val, void *data) | |
203 | { | |
204 | struct die_args *args = (struct die_args *)data; | |
205 | int ret = NOTIFY_DONE; | |
206 | ||
207 | pr_debug("kprobe_exceptions_notify: val=%lu, data=%p\n", | |
208 | val, data); | |
209 | ||
210 | switch (val) { | |
211 | case DIE_BREAKPOINT: | |
212 | if (kprobe_handler(args->regs)) | |
213 | ret = NOTIFY_STOP; | |
214 | break; | |
215 | case DIE_SSTEP: | |
216 | if (post_kprobe_handler(args->regs)) | |
217 | ret = NOTIFY_STOP; | |
218 | break; | |
219 | case DIE_FAULT: | |
220 | if (kprobe_running() | |
221 | && kprobe_fault_handler(args->regs, args->trapnr)) | |
222 | ret = NOTIFY_STOP; | |
223 | break; | |
224 | default: | |
225 | break; | |
226 | } | |
227 | ||
228 | return ret; | |
229 | } | |
230 | ||
231 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) | |
232 | { | |
233 | struct jprobe *jp = container_of(p, struct jprobe, kp); | |
234 | ||
235 | memcpy(&jprobe_saved_regs, regs, sizeof(struct pt_regs)); | |
236 | ||
237 | /* | |
238 | * TODO: We should probably save some of the stack here as | |
239 | * well, since gcc may pass arguments on the stack for certain | |
240 | * functions (lots of arguments, large aggregates, varargs) | |
241 | */ | |
242 | ||
243 | /* setup return addr to the jprobe handler routine */ | |
244 | regs->pc = (unsigned long)jp->entry; | |
245 | return 1; | |
246 | } | |
247 | ||
248 | void __kprobes jprobe_return(void) | |
249 | { | |
250 | asm volatile("breakpoint" ::: "memory"); | |
251 | } | |
252 | ||
253 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) | |
254 | { | |
255 | /* | |
256 | * FIXME - we should ideally be validating that we got here 'cos | |
257 | * of the "trap" in jprobe_return() above, before restoring the | |
258 | * saved regs... | |
259 | */ | |
260 | memcpy(regs, &jprobe_saved_regs, sizeof(struct pt_regs)); | |
261 | return 1; | |
262 | } | |
263 | ||
264 | int __init arch_init_kprobes(void) | |
265 | { | |
266 | printk("KPROBES: Enabling monitor mode (MM|DBE)...\n"); | |
267 | __mtdr(DBGREG_DC, DC_MM | DC_DBE); | |
268 | ||
269 | /* TODO: Register kretprobe trampoline */ | |
270 | return 0; | |
271 | } |