4 * Copyright (C) 2009 Jason Baron <jbaron@redhat.com>
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>
17 #ifdef HAVE_JUMP_LABEL
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
];
23 /* mutex to protect coming/going of the the jump_label table */
24 static DEFINE_MUTEX(jump_label_mutex
);
26 struct jump_label_entry
{
27 struct hlist_node hlist
;
28 struct jump_entry
*table
;
30 /* hang modules off here */
31 struct hlist_head modules
;
35 struct jump_label_module_entry
{
36 struct hlist_node hlist
;
37 struct jump_entry
*table
;
42 static int jump_label_cmp(const void *a
, const void *b
)
44 const struct jump_entry
*jea
= a
;
45 const struct jump_entry
*jeb
= b
;
47 if (jea
->key
< jeb
->key
)
50 if (jea
->key
> jeb
->key
)
57 sort_jump_label_entries(struct jump_entry
*start
, struct jump_entry
*stop
)
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
);
66 static struct jump_label_entry
*get_jump_label_entry(jump_label_t key
)
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);
73 head
= &jump_label_table
[hash
& (JUMP_LABEL_TABLE_SIZE
- 1)];
74 hlist_for_each_entry(e
, node
, head
, hlist
) {
81 static struct jump_label_entry
*
82 add_jump_label_entry(jump_label_t key
, int nr_entries
, struct jump_entry
*table
)
84 struct hlist_head
*head
;
85 struct jump_label_entry
*e
;
88 e
= get_jump_label_entry(key
);
90 return ERR_PTR(-EEXIST
);
92 e
= kmalloc(sizeof(struct jump_label_entry
), GFP_KERNEL
);
94 return ERR_PTR(-ENOMEM
);
96 hash
= jhash((void *)&key
, sizeof(jump_label_t
), 0);
97 head
= &jump_label_table
[hash
& (JUMP_LABEL_TABLE_SIZE
- 1)];
100 e
->nr_entries
= nr_entries
;
101 INIT_HLIST_HEAD(&(e
->modules
));
102 hlist_add_head(&e
->hlist
, head
);
107 build_jump_label_hashtable(struct jump_entry
*start
, struct jump_entry
*stop
)
109 struct jump_entry
*iter
, *iter_begin
;
110 struct jump_label_entry
*entry
;
113 sort_jump_label_entries(start
, stop
);
115 while (iter
< stop
) {
116 entry
= get_jump_label_entry(iter
->key
);
120 while ((iter
< stop
) &&
121 (iter
->key
== iter_begin
->key
)) {
125 entry
= add_jump_label_entry(iter_begin
->key
,
128 return PTR_ERR(entry
);
130 WARN_ONCE(1, KERN_ERR
"build_jump_hashtable: unexpected entry!\n");
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
142 * Will enable/disable the jump for jump label @key, depending on the
147 void jump_label_update(unsigned long key
, enum jump_label_type type
)
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
;
155 mutex_lock(&jump_label_mutex
);
156 entry
= get_jump_label_entry((jump_label_t
)key
);
158 count
= entry
->nr_entries
;
161 if (kernel_text_address(iter
->code
))
162 arch_jump_label_transform(iter
, type
);
165 /* eanble/disable jump labels in modules */
166 hlist_for_each_entry(e_module
, module_node
, &(entry
->modules
),
168 count
= e_module
->nr_entries
;
169 iter
= e_module
->table
;
172 kernel_text_address(iter
->code
))
173 arch_jump_label_transform(iter
, type
);
178 mutex_unlock(&jump_label_mutex
);
181 static int addr_conflict(struct jump_entry
*entry
, void *start
, void *end
)
183 if (entry
->code
<= (unsigned long)end
&&
184 entry
->code
+ JUMP_LABEL_NOP_SIZE
> (unsigned long)start
)
190 #ifdef CONFIG_MODULES
192 static int module_conflict(void *start
, void *end
)
194 struct hlist_head
*head
;
195 struct hlist_node
*node
, *node_next
, *module_node
, *module_node_next
;
196 struct jump_label_entry
*e
;
197 struct jump_label_module_entry
*e_module
;
198 struct jump_entry
*iter
;
202 for (i
= 0; i
< JUMP_LABEL_TABLE_SIZE
; i
++) {
203 head
= &jump_label_table
[i
];
204 hlist_for_each_entry_safe(e
, node
, node_next
, head
, hlist
) {
205 hlist_for_each_entry_safe(e_module
, module_node
,
207 &(e
->modules
), hlist
) {
208 count
= e_module
->nr_entries
;
209 iter
= e_module
->table
;
211 if (addr_conflict(iter
, start
, end
)) {
227 * jump_label_text_reserved - check if addr range is reserved
228 * @start: start text addr
229 * @end: end text addr
231 * checks if the text addr located between @start and @end
232 * overlaps with any of the jump label patch addresses. Code
233 * that wants to modify kernel text should first verify that
234 * it does not overlap with any of the jump label addresses.
236 * returns 1 if there is an overlap, 0 otherwise
238 int jump_label_text_reserved(void *start
, void *end
)
240 struct jump_entry
*iter
;
241 struct jump_entry
*iter_start
= __start___jump_table
;
242 struct jump_entry
*iter_stop
= __start___jump_table
;
245 mutex_lock(&jump_label_mutex
);
247 while (iter
< iter_stop
) {
248 if (addr_conflict(iter
, start
, end
)) {
255 /* now check modules */
256 #ifdef CONFIG_MODULES
257 conflict
= module_conflict(start
, end
);
260 mutex_unlock(&jump_label_mutex
);
264 static __init
int init_jump_label(void)
267 struct jump_entry
*iter_start
= __start___jump_table
;
268 struct jump_entry
*iter_stop
= __stop___jump_table
;
269 struct jump_entry
*iter
;
271 mutex_lock(&jump_label_mutex
);
272 ret
= build_jump_label_hashtable(__start___jump_table
,
273 __stop___jump_table
);
275 while (iter
< iter_stop
) {
276 arch_jump_label_text_poke_early(iter
->code
);
279 mutex_unlock(&jump_label_mutex
);
282 early_initcall(init_jump_label
);
284 #ifdef CONFIG_MODULES
286 static struct jump_label_module_entry
*
287 add_jump_label_module_entry(struct jump_label_entry
*entry
,
288 struct jump_entry
*iter_begin
,
289 int count
, struct module
*mod
)
291 struct jump_label_module_entry
*e
;
293 e
= kmalloc(sizeof(struct jump_label_module_entry
), GFP_KERNEL
);
295 return ERR_PTR(-ENOMEM
);
297 e
->nr_entries
= count
;
298 e
->table
= iter_begin
;
299 hlist_add_head(&e
->hlist
, &entry
->modules
);
303 static int add_jump_label_module(struct module
*mod
)
305 struct jump_entry
*iter
, *iter_begin
;
306 struct jump_label_entry
*entry
;
307 struct jump_label_module_entry
*module_entry
;
310 /* if the module doesn't have jump label entries, just return */
311 if (!mod
->num_jump_entries
)
314 sort_jump_label_entries(mod
->jump_entries
,
315 mod
->jump_entries
+ mod
->num_jump_entries
);
316 iter
= mod
->jump_entries
;
317 while (iter
< mod
->jump_entries
+ mod
->num_jump_entries
) {
318 entry
= get_jump_label_entry(iter
->key
);
321 while ((iter
< mod
->jump_entries
+ mod
->num_jump_entries
) &&
322 (iter
->key
== iter_begin
->key
)) {
327 entry
= add_jump_label_entry(iter_begin
->key
, 0, NULL
);
329 return PTR_ERR(entry
);
331 module_entry
= add_jump_label_module_entry(entry
, iter_begin
,
333 if (IS_ERR(module_entry
))
334 return PTR_ERR(module_entry
);
339 static void remove_jump_label_module(struct module
*mod
)
341 struct hlist_head
*head
;
342 struct hlist_node
*node
, *node_next
, *module_node
, *module_node_next
;
343 struct jump_label_entry
*e
;
344 struct jump_label_module_entry
*e_module
;
347 /* if the module doesn't have jump label entries, just return */
348 if (!mod
->num_jump_entries
)
351 for (i
= 0; i
< JUMP_LABEL_TABLE_SIZE
; i
++) {
352 head
= &jump_label_table
[i
];
353 hlist_for_each_entry_safe(e
, node
, node_next
, head
, hlist
) {
354 hlist_for_each_entry_safe(e_module
, module_node
,
356 &(e
->modules
), hlist
) {
357 if (e_module
->mod
== mod
) {
358 hlist_del(&e_module
->hlist
);
362 if (hlist_empty(&e
->modules
) && (e
->nr_entries
== 0)) {
363 hlist_del(&e
->hlist
);
370 static void remove_jump_label_module_init(struct module
*mod
)
372 struct hlist_head
*head
;
373 struct hlist_node
*node
, *node_next
, *module_node
, *module_node_next
;
374 struct jump_label_entry
*e
;
375 struct jump_label_module_entry
*e_module
;
376 struct jump_entry
*iter
;
379 /* if the module doesn't have jump label entries, just return */
380 if (!mod
->num_jump_entries
)
383 for (i
= 0; i
< JUMP_LABEL_TABLE_SIZE
; i
++) {
384 head
= &jump_label_table
[i
];
385 hlist_for_each_entry_safe(e
, node
, node_next
, head
, hlist
) {
386 hlist_for_each_entry_safe(e_module
, module_node
,
388 &(e
->modules
), hlist
) {
389 if (e_module
->mod
!= mod
)
391 count
= e_module
->nr_entries
;
392 iter
= e_module
->table
;
394 if (within_module_init(iter
->code
, mod
))
404 jump_label_module_notify(struct notifier_block
*self
, unsigned long val
,
407 struct module
*mod
= data
;
411 case MODULE_STATE_COMING
:
412 mutex_lock(&jump_label_mutex
);
413 ret
= add_jump_label_module(mod
);
415 remove_jump_label_module(mod
);
416 mutex_unlock(&jump_label_mutex
);
418 case MODULE_STATE_GOING
:
419 mutex_lock(&jump_label_mutex
);
420 remove_jump_label_module(mod
);
421 mutex_unlock(&jump_label_mutex
);
423 case MODULE_STATE_LIVE
:
424 mutex_lock(&jump_label_mutex
);
425 remove_jump_label_module_init(mod
);
426 mutex_unlock(&jump_label_mutex
);
433 * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
434 * @mod: module to patch
436 * Allow for run-time selection of the optimal nops. Before the module
437 * loads patch these with arch_get_jump_label_nop(), which is specified by
438 * the arch specific jump label code.
440 void jump_label_apply_nops(struct module
*mod
)
442 struct jump_entry
*iter
;
444 /* if the module doesn't have jump label entries, just return */
445 if (!mod
->num_jump_entries
)
448 iter
= mod
->jump_entries
;
449 while (iter
< mod
->jump_entries
+ mod
->num_jump_entries
) {
450 arch_jump_label_text_poke_early(iter
->code
);
455 struct notifier_block jump_label_module_nb
= {
456 .notifier_call
= jump_label_module_notify
,
460 static __init
int init_jump_label_module(void)
462 return register_module_notifier(&jump_label_module_nb
);
464 early_initcall(init_jump_label_module
);
466 #endif /* CONFIG_MODULES */