Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/kernel/kprobes.c
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
File MIME type: text/plain
File size: 7312 byte(s)
Tag kernel26-2.6.12-alx-r9
1 | /* |
2 | * Kernel Probes (KProbes) |
3 | * kernel/kprobes.c |
4 | * |
5 | * This program is free software; you can redistribute it and/or modify |
6 | * it under the terms of the GNU General Public License as published by |
7 | * the Free Software Foundation; either version 2 of the License, or |
8 | * (at your option) any later version. |
9 | * |
10 | * This program is distributed in the hope that it will be useful, |
11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
13 | * GNU General Public License for more details. |
14 | * |
15 | * You should have received a copy of the GNU General Public License |
16 | * along with this program; if not, write to the Free Software |
17 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
18 | * |
19 | * Copyright (C) IBM Corporation, 2002, 2004 |
20 | * |
21 | * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel |
22 | * Probes initial implementation (includes suggestions from |
23 | * Rusty Russell). |
24 | * 2004-Aug Updated by Prasanna S Panchamukhi <prasanna@in.ibm.com> with |
25 | * hlists and exceptions notifier as suggested by Andi Kleen. |
26 | * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes |
27 | * interface to access function arguments. |
28 | * 2004-Sep Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes |
29 | * exceptions notifier to be first on the priority list. |
30 | */ |
31 | #include <linux/kprobes.h> |
32 | #include <linux/spinlock.h> |
33 | #include <linux/hash.h> |
34 | #include <linux/init.h> |
35 | #include <linux/module.h> |
36 | #include <asm/cacheflush.h> |
37 | #include <asm/errno.h> |
38 | #include <asm/kdebug.h> |
39 | |
40 | #define KPROBE_HASH_BITS 6 |
41 | #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS) |
42 | |
43 | static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE]; |
44 | |
45 | unsigned int kprobe_cpu = NR_CPUS; |
46 | static DEFINE_SPINLOCK(kprobe_lock); |
47 | static struct kprobe *curr_kprobe; |
48 | |
49 | /* Locks kprobe: irqs must be disabled */ |
50 | void lock_kprobes(void) |
51 | { |
52 | spin_lock(&kprobe_lock); |
53 | kprobe_cpu = smp_processor_id(); |
54 | } |
55 | |
56 | void unlock_kprobes(void) |
57 | { |
58 | kprobe_cpu = NR_CPUS; |
59 | spin_unlock(&kprobe_lock); |
60 | } |
61 | |
62 | /* You have to be holding the kprobe_lock */ |
63 | struct kprobe *get_kprobe(void *addr) |
64 | { |
65 | struct hlist_head *head; |
66 | struct hlist_node *node; |
67 | |
68 | head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)]; |
69 | hlist_for_each(node, head) { |
70 | struct kprobe *p = hlist_entry(node, struct kprobe, hlist); |
71 | if (p->addr == addr) |
72 | return p; |
73 | } |
74 | return NULL; |
75 | } |
76 | |
77 | /* |
78 | * Aggregate handlers for multiple kprobes support - these handlers |
79 | * take care of invoking the individual kprobe handlers on p->list |
80 | */ |
81 | int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs) |
82 | { |
83 | struct kprobe *kp; |
84 | |
85 | list_for_each_entry(kp, &p->list, list) { |
86 | if (kp->pre_handler) { |
87 | curr_kprobe = kp; |
88 | kp->pre_handler(kp, regs); |
89 | curr_kprobe = NULL; |
90 | } |
91 | } |
92 | return 0; |
93 | } |
94 | |
95 | void aggr_post_handler(struct kprobe *p, struct pt_regs *regs, |
96 | unsigned long flags) |
97 | { |
98 | struct kprobe *kp; |
99 | |
100 | list_for_each_entry(kp, &p->list, list) { |
101 | if (kp->post_handler) { |
102 | curr_kprobe = kp; |
103 | kp->post_handler(kp, regs, flags); |
104 | curr_kprobe = NULL; |
105 | } |
106 | } |
107 | return; |
108 | } |
109 | |
110 | int aggr_fault_handler(struct kprobe *p, struct pt_regs *regs, int trapnr) |
111 | { |
112 | /* |
113 | * if we faulted "during" the execution of a user specified |
114 | * probe handler, invoke just that probe's fault handler |
115 | */ |
116 | if (curr_kprobe && curr_kprobe->fault_handler) { |
117 | if (curr_kprobe->fault_handler(curr_kprobe, regs, trapnr)) |
118 | return 1; |
119 | } |
120 | return 0; |
121 | } |
122 | |
123 | /* |
124 | * Fill in the required fields of the "manager kprobe". Replace the |
125 | * earlier kprobe in the hlist with the manager kprobe |
126 | */ |
127 | static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p) |
128 | { |
129 | ap->addr = p->addr; |
130 | ap->opcode = p->opcode; |
131 | memcpy(&ap->ainsn, &p->ainsn, sizeof(struct arch_specific_insn)); |
132 | |
133 | ap->pre_handler = aggr_pre_handler; |
134 | ap->post_handler = aggr_post_handler; |
135 | ap->fault_handler = aggr_fault_handler; |
136 | |
137 | INIT_LIST_HEAD(&ap->list); |
138 | list_add(&p->list, &ap->list); |
139 | |
140 | INIT_HLIST_NODE(&ap->hlist); |
141 | hlist_del(&p->hlist); |
142 | hlist_add_head(&ap->hlist, |
143 | &kprobe_table[hash_ptr(ap->addr, KPROBE_HASH_BITS)]); |
144 | } |
145 | |
146 | /* |
147 | * This is the second or subsequent kprobe at the address - handle |
148 | * the intricacies |
149 | * TODO: Move kcalloc outside the spinlock |
150 | */ |
151 | static int register_aggr_kprobe(struct kprobe *old_p, struct kprobe *p) |
152 | { |
153 | int ret = 0; |
154 | struct kprobe *ap; |
155 | |
156 | if (old_p->break_handler || p->break_handler) { |
157 | ret = -EEXIST; /* kprobe and jprobe can't (yet) coexist */ |
158 | } else if (old_p->pre_handler == aggr_pre_handler) { |
159 | list_add(&p->list, &old_p->list); |
160 | } else { |
161 | ap = kcalloc(1, sizeof(struct kprobe), GFP_ATOMIC); |
162 | if (!ap) |
163 | return -ENOMEM; |
164 | add_aggr_kprobe(ap, old_p); |
165 | list_add(&p->list, &ap->list); |
166 | } |
167 | return ret; |
168 | } |
169 | |
170 | /* kprobe removal house-keeping routines */ |
171 | static inline void cleanup_kprobe(struct kprobe *p, unsigned long flags) |
172 | { |
173 | *p->addr = p->opcode; |
174 | hlist_del(&p->hlist); |
175 | flush_icache_range((unsigned long) p->addr, |
176 | (unsigned long) p->addr + sizeof(kprobe_opcode_t)); |
177 | spin_unlock_irqrestore(&kprobe_lock, flags); |
178 | arch_remove_kprobe(p); |
179 | } |
180 | |
181 | static inline void cleanup_aggr_kprobe(struct kprobe *old_p, |
182 | struct kprobe *p, unsigned long flags) |
183 | { |
184 | list_del(&p->list); |
185 | if (list_empty(&old_p->list)) { |
186 | cleanup_kprobe(old_p, flags); |
187 | kfree(old_p); |
188 | } else |
189 | spin_unlock_irqrestore(&kprobe_lock, flags); |
190 | } |
191 | |
192 | int register_kprobe(struct kprobe *p) |
193 | { |
194 | int ret = 0; |
195 | unsigned long flags = 0; |
196 | struct kprobe *old_p; |
197 | |
198 | if ((ret = arch_prepare_kprobe(p)) != 0) { |
199 | goto rm_kprobe; |
200 | } |
201 | spin_lock_irqsave(&kprobe_lock, flags); |
202 | old_p = get_kprobe(p->addr); |
203 | if (old_p) { |
204 | ret = register_aggr_kprobe(old_p, p); |
205 | goto out; |
206 | } |
207 | |
208 | arch_copy_kprobe(p); |
209 | INIT_HLIST_NODE(&p->hlist); |
210 | hlist_add_head(&p->hlist, |
211 | &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]); |
212 | |
213 | p->opcode = *p->addr; |
214 | *p->addr = BREAKPOINT_INSTRUCTION; |
215 | flush_icache_range((unsigned long) p->addr, |
216 | (unsigned long) p->addr + sizeof(kprobe_opcode_t)); |
217 | out: |
218 | spin_unlock_irqrestore(&kprobe_lock, flags); |
219 | rm_kprobe: |
220 | if (ret == -EEXIST) |
221 | arch_remove_kprobe(p); |
222 | return ret; |
223 | } |
224 | |
225 | void unregister_kprobe(struct kprobe *p) |
226 | { |
227 | unsigned long flags; |
228 | struct kprobe *old_p; |
229 | |
230 | spin_lock_irqsave(&kprobe_lock, flags); |
231 | old_p = get_kprobe(p->addr); |
232 | if (old_p) { |
233 | if (old_p->pre_handler == aggr_pre_handler) |
234 | cleanup_aggr_kprobe(old_p, p, flags); |
235 | else |
236 | cleanup_kprobe(p, flags); |
237 | } else |
238 | spin_unlock_irqrestore(&kprobe_lock, flags); |
239 | } |
240 | |
241 | static struct notifier_block kprobe_exceptions_nb = { |
242 | .notifier_call = kprobe_exceptions_notify, |
243 | .priority = 0x7fffffff /* we need to notified first */ |
244 | }; |
245 | |
246 | int register_jprobe(struct jprobe *jp) |
247 | { |
248 | /* Todo: Verify probepoint is a function entry point */ |
249 | jp->kp.pre_handler = setjmp_pre_handler; |
250 | jp->kp.break_handler = longjmp_break_handler; |
251 | |
252 | return register_kprobe(&jp->kp); |
253 | } |
254 | |
255 | void unregister_jprobe(struct jprobe *jp) |
256 | { |
257 | unregister_kprobe(&jp->kp); |
258 | } |
259 | |
260 | static int __init init_kprobes(void) |
261 | { |
262 | int i, err = 0; |
263 | |
264 | /* FIXME allocate the probe table, currently defined statically */ |
265 | /* initialize all list heads */ |
266 | for (i = 0; i < KPROBE_TABLE_SIZE; i++) |
267 | INIT_HLIST_HEAD(&kprobe_table[i]); |
268 | |
269 | err = register_die_notifier(&kprobe_exceptions_nb); |
270 | return err; |
271 | } |
272 | |
273 | __initcall(init_kprobes); |
274 | |
275 | EXPORT_SYMBOL_GPL(register_kprobe); |
276 | EXPORT_SYMBOL_GPL(unregister_kprobe); |
277 | EXPORT_SYMBOL_GPL(register_jprobe); |
278 | EXPORT_SYMBOL_GPL(unregister_jprobe); |
279 | EXPORT_SYMBOL_GPL(jprobe_return); |