diff options
Diffstat (limited to 'kernel/jump_label.c')
-rw-r--r-- | kernel/jump_label.c | 346 |
1 files changed, 346 insertions, 0 deletions
diff --git a/kernel/jump_label.c b/kernel/jump_label.c new file mode 100644 index 00000000000..460fd40112b --- /dev/null +++ b/kernel/jump_label.c | |||
@@ -0,0 +1,346 @@ | |||
1 | /* | ||
2 | * jump label support | ||
3 | * | ||
4 | * Copyright (C) 2009 Jason Baron <jbaron@redhat.com> | ||
5 | * | ||
6 | */ | ||
7 | #include <linux/jump_label.h> | ||
8 | #include <linux/memory.h> | ||
9 | #include <linux/uaccess.h> | ||
10 | #include <linux/module.h> | ||
11 | #include <linux/list.h> | ||
12 | #include <linux/jhash.h> | ||
13 | #include <linux/slab.h> | ||
14 | #include <linux/sort.h> | ||
15 | #include <linux/err.h> | ||
16 | |||
17 | #ifdef HAVE_JUMP_LABEL | ||
18 | |||
19 | #define JUMP_LABEL_HASH_BITS 6 | ||
20 | #define JUMP_LABEL_TABLE_SIZE (1 << JUMP_LABEL_HASH_BITS) | ||
21 | static struct hlist_head jump_label_table[JUMP_LABEL_TABLE_SIZE]; | ||
22 | |||
23 | /* mutex to protect coming/going of the the jump_label table */ | ||
24 | static DEFINE_MUTEX(jump_label_mutex); | ||
25 | |||
26 | struct jump_label_entry { | ||
27 | struct hlist_node hlist; | ||
28 | struct jump_entry *table; | ||
29 | int nr_entries; | ||
30 | /* hang modules off here */ | ||
31 | struct hlist_head modules; | ||
32 | unsigned long key; | ||
33 | }; | ||
34 | |||
35 | struct jump_label_module_entry { | ||
36 | struct hlist_node hlist; | ||
37 | struct jump_entry *table; | ||
38 | int nr_entries; | ||
39 | struct module *mod; | ||
40 | }; | ||
41 | |||
42 | static int jump_label_cmp(const void *a, const void *b) | ||
43 | { | ||
44 | const struct jump_entry *jea = a; | ||
45 | const struct jump_entry *jeb = b; | ||
46 | |||
47 | if (jea->key < jeb->key) | ||
48 | return -1; | ||
49 | |||
50 | if (jea->key > jeb->key) | ||
51 | return 1; | ||
52 | |||
53 | return 0; | ||
54 | } | ||
55 | |||
56 | static void | ||
57 | sort_jump_label_entries(struct jump_entry *start, struct jump_entry *stop) | ||
58 | { | ||
59 | unsigned long size; | ||
60 | |||
61 | size = (((unsigned long)stop - (unsigned long)start) | ||
62 | / sizeof(struct jump_entry)); | ||
63 | sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL); | ||
64 | } | ||
65 | |||
66 | static struct jump_label_entry *get_jump_label_entry(jump_label_t key) | ||
67 | { | ||
68 | struct hlist_head *head; | ||
69 | struct hlist_node *node; | ||
70 | struct jump_label_entry *e; | ||
71 | u32 hash = jhash((void *)&key, sizeof(jump_label_t), 0); | ||
72 | |||
73 | head = &jump_label_table[hash & (JUMP_LABEL_TABLE_SIZE - 1)]; | ||
74 | hlist_for_each_entry(e, node, head, hlist) { | ||
75 | if (key == e->key) | ||
76 | return e; | ||
77 | } | ||
78 | return NULL; | ||
79 | } | ||
80 | |||
81 | static struct jump_label_entry * | ||
82 | add_jump_label_entry(jump_label_t key, int nr_entries, struct jump_entry *table) | ||
83 | { | ||
84 | struct hlist_head *head; | ||
85 | struct jump_label_entry *e; | ||
86 | u32 hash; | ||
87 | |||
88 | e = get_jump_label_entry(key); | ||
89 | if (e) | ||
90 | return ERR_PTR(-EEXIST); | ||
91 | |||
92 | e = kmalloc(sizeof(struct jump_label_entry), GFP_KERNEL); | ||
93 | if (!e) | ||
94 | return ERR_PTR(-ENOMEM); | ||
95 | |||
96 | hash = jhash((void *)&key, sizeof(jump_label_t), 0); | ||
97 | head = &jump_label_table[hash & (JUMP_LABEL_TABLE_SIZE - 1)]; | ||
98 | e->key = key; | ||
99 | e->table = table; | ||
100 | e->nr_entries = nr_entries; | ||
101 | INIT_HLIST_HEAD(&(e->modules)); | ||
102 | hlist_add_head(&e->hlist, head); | ||
103 | return e; | ||
104 | } | ||
105 | |||
106 | static int | ||
107 | build_jump_label_hashtable(struct jump_entry *start, struct jump_entry *stop) | ||
108 | { | ||
109 | struct jump_entry *iter, *iter_begin; | ||
110 | struct jump_label_entry *entry; | ||
111 | int count; | ||
112 | |||
113 | sort_jump_label_entries(start, stop); | ||
114 | iter = start; | ||
115 | while (iter < stop) { | ||
116 | entry = get_jump_label_entry(iter->key); | ||
117 | if (!entry) { | ||
118 | iter_begin = iter; | ||
119 | count = 0; | ||
120 | while ((iter < stop) && | ||
121 | (iter->key == iter_begin->key)) { | ||
122 | iter++; | ||
123 | count++; | ||
124 | } | ||
125 | entry = add_jump_label_entry(iter_begin->key, | ||
126 | count, iter_begin); | ||
127 | if (IS_ERR(entry)) | ||
128 | return PTR_ERR(entry); | ||
129 | } else { | ||
130 | WARN_ONCE(1, KERN_ERR "build_jump_hashtable: unexpected entry!\n"); | ||
131 | return -1; | ||
132 | } | ||
133 | } | ||
134 | return 0; | ||
135 | } | ||
136 | |||
137 | /*** | ||
138 | * jump_label_update - update jump label text | ||
139 | * @key - key value associated with a a jump label | ||
140 | * @type - enum set to JUMP_LABEL_ENABLE or JUMP_LABEL_DISABLE | ||
141 | * | ||
142 | * Will enable/disable the jump for jump label @key, depending on the | ||
143 | * value of @type. | ||
144 | * | ||
145 | */ | ||
146 | |||
147 | void jump_label_update(unsigned long key, enum jump_label_type type) | ||
148 | { | ||
149 | struct jump_entry *iter; | ||
150 | struct jump_label_entry *entry; | ||
151 | struct hlist_node *module_node; | ||
152 | struct jump_label_module_entry *e_module; | ||
153 | int count; | ||
154 | |||
155 | mutex_lock(&jump_label_mutex); | ||
156 | entry = get_jump_label_entry((jump_label_t)key); | ||
157 | if (entry) { | ||
158 | count = entry->nr_entries; | ||
159 | iter = entry->table; | ||
160 | while (count--) { | ||
161 | if (kernel_text_address(iter->code)) | ||
162 | arch_jump_label_transform(iter, type); | ||
163 | iter++; | ||
164 | } | ||
165 | /* eanble/disable jump labels in modules */ | ||
166 | hlist_for_each_entry(e_module, module_node, &(entry->modules), | ||
167 | hlist) { | ||
168 | count = e_module->nr_entries; | ||
169 | iter = e_module->table; | ||
170 | while (count--) { | ||
171 | if (kernel_text_address(iter->code)) | ||
172 | arch_jump_label_transform(iter, type); | ||
173 | iter++; | ||
174 | } | ||
175 | } | ||
176 | } | ||
177 | mutex_unlock(&jump_label_mutex); | ||
178 | } | ||
179 | |||
180 | static __init int init_jump_label(void) | ||
181 | { | ||
182 | int ret; | ||
183 | struct jump_entry *iter_start = __start___jump_table; | ||
184 | struct jump_entry *iter_stop = __stop___jump_table; | ||
185 | struct jump_entry *iter; | ||
186 | |||
187 | mutex_lock(&jump_label_mutex); | ||
188 | ret = build_jump_label_hashtable(__start___jump_table, | ||
189 | __stop___jump_table); | ||
190 | iter = iter_start; | ||
191 | while (iter < iter_stop) { | ||
192 | arch_jump_label_text_poke_early(iter->code); | ||
193 | iter++; | ||
194 | } | ||
195 | mutex_unlock(&jump_label_mutex); | ||
196 | return ret; | ||
197 | } | ||
198 | early_initcall(init_jump_label); | ||
199 | |||
200 | #ifdef CONFIG_MODULES | ||
201 | |||
202 | static struct jump_label_module_entry * | ||
203 | add_jump_label_module_entry(struct jump_label_entry *entry, | ||
204 | struct jump_entry *iter_begin, | ||
205 | int count, struct module *mod) | ||
206 | { | ||
207 | struct jump_label_module_entry *e; | ||
208 | |||
209 | e = kmalloc(sizeof(struct jump_label_module_entry), GFP_KERNEL); | ||
210 | if (!e) | ||
211 | return ERR_PTR(-ENOMEM); | ||
212 | e->mod = mod; | ||
213 | e->nr_entries = count; | ||
214 | e->table = iter_begin; | ||
215 | hlist_add_head(&e->hlist, &entry->modules); | ||
216 | return e; | ||
217 | } | ||
218 | |||
219 | static int add_jump_label_module(struct module *mod) | ||
220 | { | ||
221 | struct jump_entry *iter, *iter_begin; | ||
222 | struct jump_label_entry *entry; | ||
223 | struct jump_label_module_entry *module_entry; | ||
224 | int count; | ||
225 | |||
226 | /* if the module doesn't have jump label entries, just return */ | ||
227 | if (!mod->num_jump_entries) | ||
228 | return 0; | ||
229 | |||
230 | sort_jump_label_entries(mod->jump_entries, | ||
231 | mod->jump_entries + mod->num_jump_entries); | ||
232 | iter = mod->jump_entries; | ||
233 | while (iter < mod->jump_entries + mod->num_jump_entries) { | ||
234 | entry = get_jump_label_entry(iter->key); | ||
235 | iter_begin = iter; | ||
236 | count = 0; | ||
237 | while ((iter < mod->jump_entries + mod->num_jump_entries) && | ||
238 | (iter->key == iter_begin->key)) { | ||
239 | iter++; | ||
240 | count++; | ||
241 | } | ||
242 | if (!entry) { | ||
243 | entry = add_jump_label_entry(iter_begin->key, 0, NULL); | ||
244 | if (IS_ERR(entry)) | ||
245 | return PTR_ERR(entry); | ||
246 | } | ||
247 | module_entry = add_jump_label_module_entry(entry, iter_begin, | ||
248 | count, mod); | ||
249 | if (IS_ERR(module_entry)) | ||
250 | return PTR_ERR(module_entry); | ||
251 | } | ||
252 | return 0; | ||
253 | } | ||
254 | |||
255 | static void remove_jump_label_module(struct module *mod) | ||
256 | { | ||
257 | struct hlist_head *head; | ||
258 | struct hlist_node *node, *node_next, *module_node, *module_node_next; | ||
259 | struct jump_label_entry *e; | ||
260 | struct jump_label_module_entry *e_module; | ||
261 | int i; | ||
262 | |||
263 | /* if the module doesn't have jump label entries, just return */ | ||
264 | if (!mod->num_jump_entries) | ||
265 | return; | ||
266 | |||
267 | for (i = 0; i < JUMP_LABEL_TABLE_SIZE; i++) { | ||
268 | head = &jump_label_table[i]; | ||
269 | hlist_for_each_entry_safe(e, node, node_next, head, hlist) { | ||
270 | hlist_for_each_entry_safe(e_module, module_node, | ||
271 | module_node_next, | ||
272 | &(e->modules), hlist) { | ||
273 | if (e_module->mod == mod) { | ||
274 | hlist_del(&e_module->hlist); | ||
275 | kfree(e_module); | ||
276 | } | ||
277 | } | ||
278 | if (hlist_empty(&e->modules) && (e->nr_entries == 0)) { | ||
279 | hlist_del(&e->hlist); | ||
280 | kfree(e); | ||
281 | } | ||
282 | } | ||
283 | } | ||
284 | } | ||
285 | |||
286 | static int | ||
287 | jump_label_module_notify(struct notifier_block *self, unsigned long val, | ||
288 | void *data) | ||
289 | { | ||
290 | struct module *mod = data; | ||
291 | int ret = 0; | ||
292 | |||
293 | switch (val) { | ||
294 | case MODULE_STATE_COMING: | ||
295 | mutex_lock(&jump_label_mutex); | ||
296 | ret = add_jump_label_module(mod); | ||
297 | if (ret) | ||
298 | remove_jump_label_module(mod); | ||
299 | mutex_unlock(&jump_label_mutex); | ||
300 | break; | ||
301 | case MODULE_STATE_GOING: | ||
302 | mutex_lock(&jump_label_mutex); | ||
303 | remove_jump_label_module(mod); | ||
304 | mutex_unlock(&jump_label_mutex); | ||
305 | break; | ||
306 | } | ||
307 | return ret; | ||
308 | } | ||
309 | |||
310 | /*** | ||
311 | * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop() | ||
312 | * @mod: module to patch | ||
313 | * | ||
314 | * Allow for run-time selection of the optimal nops. Before the module | ||
315 | * loads patch these with arch_get_jump_label_nop(), which is specified by | ||
316 | * the arch specific jump label code. | ||
317 | */ | ||
318 | void jump_label_apply_nops(struct module *mod) | ||
319 | { | ||
320 | struct jump_entry *iter; | ||
321 | |||
322 | /* if the module doesn't have jump label entries, just return */ | ||
323 | if (!mod->num_jump_entries) | ||
324 | return; | ||
325 | |||
326 | iter = mod->jump_entries; | ||
327 | while (iter < mod->jump_entries + mod->num_jump_entries) { | ||
328 | arch_jump_label_text_poke_early(iter->code); | ||
329 | iter++; | ||
330 | } | ||
331 | } | ||
332 | |||
333 | struct notifier_block jump_label_module_nb = { | ||
334 | .notifier_call = jump_label_module_notify, | ||
335 | .priority = 0, | ||
336 | }; | ||
337 | |||
338 | static __init int init_jump_label_module(void) | ||
339 | { | ||
340 | return register_module_notifier(&jump_label_module_nb); | ||
341 | } | ||
342 | early_initcall(init_jump_label_module); | ||
343 | |||
344 | #endif /* CONFIG_MODULES */ | ||
345 | |||
346 | #endif | ||