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-rw-r--r--kernel/jump_label.c429
1 files changed, 429 insertions, 0 deletions
diff --git a/kernel/jump_label.c b/kernel/jump_label.c
new file mode 100644
index 000000000000..7be868bf25c6
--- /dev/null
+++ b/kernel/jump_label.c
@@ -0,0 +1,429 @@
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)
21static struct hlist_head jump_label_table[JUMP_LABEL_TABLE_SIZE];
22
23/* mutex to protect coming/going of the the jump_label table */
24static DEFINE_MUTEX(jump_label_mutex);
25
26struct 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
35struct jump_label_module_entry {
36 struct hlist_node hlist;
37 struct jump_entry *table;
38 int nr_entries;
39 struct module *mod;
40};
41
42static 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
56static void
57sort_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
66static 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
81static struct jump_label_entry *
82add_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
106static int
107build_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
147void 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
180static int addr_conflict(struct jump_entry *entry, void *start, void *end)
181{
182 if (entry->code <= (unsigned long)end &&
183 entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
184 return 1;
185
186 return 0;
187}
188
189#ifdef CONFIG_MODULES
190
191static int module_conflict(void *start, void *end)
192{
193 struct hlist_head *head;
194 struct hlist_node *node, *node_next, *module_node, *module_node_next;
195 struct jump_label_entry *e;
196 struct jump_label_module_entry *e_module;
197 struct jump_entry *iter;
198 int i, count;
199 int conflict = 0;
200
201 for (i = 0; i < JUMP_LABEL_TABLE_SIZE; i++) {
202 head = &jump_label_table[i];
203 hlist_for_each_entry_safe(e, node, node_next, head, hlist) {
204 hlist_for_each_entry_safe(e_module, module_node,
205 module_node_next,
206 &(e->modules), hlist) {
207 count = e_module->nr_entries;
208 iter = e_module->table;
209 while (count--) {
210 if (addr_conflict(iter, start, end)) {
211 conflict = 1;
212 goto out;
213 }
214 iter++;
215 }
216 }
217 }
218 }
219out:
220 return conflict;
221}
222
223#endif
224
225/***
226 * jump_label_text_reserved - check if addr range is reserved
227 * @start: start text addr
228 * @end: end text addr
229 *
230 * checks if the text addr located between @start and @end
231 * overlaps with any of the jump label patch addresses. Code
232 * that wants to modify kernel text should first verify that
233 * it does not overlap with any of the jump label addresses.
234 *
235 * returns 1 if there is an overlap, 0 otherwise
236 */
237int jump_label_text_reserved(void *start, void *end)
238{
239 struct jump_entry *iter;
240 struct jump_entry *iter_start = __start___jump_table;
241 struct jump_entry *iter_stop = __start___jump_table;
242 int conflict = 0;
243
244 mutex_lock(&jump_label_mutex);
245 iter = iter_start;
246 while (iter < iter_stop) {
247 if (addr_conflict(iter, start, end)) {
248 conflict = 1;
249 goto out;
250 }
251 iter++;
252 }
253
254 /* now check modules */
255#ifdef CONFIG_MODULES
256 conflict = module_conflict(start, end);
257#endif
258out:
259 mutex_unlock(&jump_label_mutex);
260 return conflict;
261}
262
263static __init int init_jump_label(void)
264{
265 int ret;
266 struct jump_entry *iter_start = __start___jump_table;
267 struct jump_entry *iter_stop = __stop___jump_table;
268 struct jump_entry *iter;
269
270 mutex_lock(&jump_label_mutex);
271 ret = build_jump_label_hashtable(__start___jump_table,
272 __stop___jump_table);
273 iter = iter_start;
274 while (iter < iter_stop) {
275 arch_jump_label_text_poke_early(iter->code);
276 iter++;
277 }
278 mutex_unlock(&jump_label_mutex);
279 return ret;
280}
281early_initcall(init_jump_label);
282
283#ifdef CONFIG_MODULES
284
285static struct jump_label_module_entry *
286add_jump_label_module_entry(struct jump_label_entry *entry,
287 struct jump_entry *iter_begin,
288 int count, struct module *mod)
289{
290 struct jump_label_module_entry *e;
291
292 e = kmalloc(sizeof(struct jump_label_module_entry), GFP_KERNEL);
293 if (!e)
294 return ERR_PTR(-ENOMEM);
295 e->mod = mod;
296 e->nr_entries = count;
297 e->table = iter_begin;
298 hlist_add_head(&e->hlist, &entry->modules);
299 return e;
300}
301
302static int add_jump_label_module(struct module *mod)
303{
304 struct jump_entry *iter, *iter_begin;
305 struct jump_label_entry *entry;
306 struct jump_label_module_entry *module_entry;
307 int count;
308
309 /* if the module doesn't have jump label entries, just return */
310 if (!mod->num_jump_entries)
311 return 0;
312
313 sort_jump_label_entries(mod->jump_entries,
314 mod->jump_entries + mod->num_jump_entries);
315 iter = mod->jump_entries;
316 while (iter < mod->jump_entries + mod->num_jump_entries) {
317 entry = get_jump_label_entry(iter->key);
318 iter_begin = iter;
319 count = 0;
320 while ((iter < mod->jump_entries + mod->num_jump_entries) &&
321 (iter->key == iter_begin->key)) {
322 iter++;
323 count++;
324 }
325 if (!entry) {
326 entry = add_jump_label_entry(iter_begin->key, 0, NULL);
327 if (IS_ERR(entry))
328 return PTR_ERR(entry);
329 }
330 module_entry = add_jump_label_module_entry(entry, iter_begin,
331 count, mod);
332 if (IS_ERR(module_entry))
333 return PTR_ERR(module_entry);
334 }
335 return 0;
336}
337
338static void remove_jump_label_module(struct module *mod)
339{
340 struct hlist_head *head;
341 struct hlist_node *node, *node_next, *module_node, *module_node_next;
342 struct jump_label_entry *e;
343 struct jump_label_module_entry *e_module;
344 int i;
345
346 /* if the module doesn't have jump label entries, just return */
347 if (!mod->num_jump_entries)
348 return;
349
350 for (i = 0; i < JUMP_LABEL_TABLE_SIZE; i++) {
351 head = &jump_label_table[i];
352 hlist_for_each_entry_safe(e, node, node_next, head, hlist) {
353 hlist_for_each_entry_safe(e_module, module_node,
354 module_node_next,
355 &(e->modules), hlist) {
356 if (e_module->mod == mod) {
357 hlist_del(&e_module->hlist);
358 kfree(e_module);
359 }
360 }
361 if (hlist_empty(&e->modules) && (e->nr_entries == 0)) {
362 hlist_del(&e->hlist);
363 kfree(e);
364 }
365 }
366 }
367}
368
369static int
370jump_label_module_notify(struct notifier_block *self, unsigned long val,
371 void *data)
372{
373 struct module *mod = data;
374 int ret = 0;
375
376 switch (val) {
377 case MODULE_STATE_COMING:
378 mutex_lock(&jump_label_mutex);
379 ret = add_jump_label_module(mod);
380 if (ret)
381 remove_jump_label_module(mod);
382 mutex_unlock(&jump_label_mutex);
383 break;
384 case MODULE_STATE_GOING:
385 mutex_lock(&jump_label_mutex);
386 remove_jump_label_module(mod);
387 mutex_unlock(&jump_label_mutex);
388 break;
389 }
390 return ret;
391}
392
393/***
394 * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
395 * @mod: module to patch
396 *
397 * Allow for run-time selection of the optimal nops. Before the module
398 * loads patch these with arch_get_jump_label_nop(), which is specified by
399 * the arch specific jump label code.
400 */
401void jump_label_apply_nops(struct module *mod)
402{
403 struct jump_entry *iter;
404
405 /* if the module doesn't have jump label entries, just return */
406 if (!mod->num_jump_entries)
407 return;
408
409 iter = mod->jump_entries;
410 while (iter < mod->jump_entries + mod->num_jump_entries) {
411 arch_jump_label_text_poke_early(iter->code);
412 iter++;
413 }
414}
415
416struct notifier_block jump_label_module_nb = {
417 .notifier_call = jump_label_module_notify,
418 .priority = 0,
419};
420
421static __init int init_jump_label_module(void)
422{
423 return register_module_notifier(&jump_label_module_nb);
424}
425early_initcall(init_jump_label_module);
426
427#endif /* CONFIG_MODULES */
428
429#endif
generated by cgit v1.2.2 (git 2.25.0) at 2024-12-13 18:09:29 -0500