Commit | Line | Data |
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2b144498 | 1 | /* |
7b2d81d4 | 2 | * User-space Probes (UProbes) |
2b144498 SD |
3 | * |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License as published by | |
6 | * the Free Software Foundation; either version 2 of the License, or | |
7 | * (at your option) any later version. | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | * GNU General Public License for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License | |
15 | * along with this program; if not, write to the Free Software | |
16 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
17 | * | |
35aa621b | 18 | * Copyright (C) IBM Corporation, 2008-2012 |
2b144498 SD |
19 | * Authors: |
20 | * Srikar Dronamraju | |
21 | * Jim Keniston | |
35aa621b | 22 | * Copyright (C) 2011-2012 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com> |
2b144498 SD |
23 | */ |
24 | ||
25 | #include <linux/kernel.h> | |
26 | #include <linux/highmem.h> | |
27 | #include <linux/pagemap.h> /* read_mapping_page */ | |
28 | #include <linux/slab.h> | |
29 | #include <linux/sched.h> | |
30 | #include <linux/rmap.h> /* anon_vma_prepare */ | |
31 | #include <linux/mmu_notifier.h> /* set_pte_at_notify */ | |
32 | #include <linux/swap.h> /* try_to_free_swap */ | |
0326f5a9 SD |
33 | #include <linux/ptrace.h> /* user_enable_single_step */ |
34 | #include <linux/kdebug.h> /* notifier mechanism */ | |
7b2d81d4 | 35 | |
2b144498 SD |
36 | #include <linux/uprobes.h> |
37 | ||
d4b3b638 SD |
38 | #define UINSNS_PER_PAGE (PAGE_SIZE/UPROBE_XOL_SLOT_BYTES) |
39 | #define MAX_UPROBE_XOL_SLOTS UINSNS_PER_PAGE | |
40 | ||
2b144498 | 41 | static struct rb_root uprobes_tree = RB_ROOT; |
7b2d81d4 | 42 | |
2b144498 SD |
43 | static DEFINE_SPINLOCK(uprobes_treelock); /* serialize rbtree access */ |
44 | ||
45 | #define UPROBES_HASH_SZ 13 | |
7b2d81d4 | 46 | |
c5784de2 PZ |
47 | /* |
48 | * We need separate register/unregister and mmap/munmap lock hashes because | |
49 | * of mmap_sem nesting. | |
50 | * | |
51 | * uprobe_register() needs to install probes on (potentially) all processes | |
52 | * and thus needs to acquire multiple mmap_sems (consequtively, not | |
53 | * concurrently), whereas uprobe_mmap() is called while holding mmap_sem | |
54 | * for the particular process doing the mmap. | |
55 | * | |
56 | * uprobe_register()->register_for_each_vma() needs to drop/acquire mmap_sem | |
57 | * because of lock order against i_mmap_mutex. This means there's a hole in | |
58 | * the register vma iteration where a mmap() can happen. | |
59 | * | |
60 | * Thus uprobe_register() can race with uprobe_mmap() and we can try and | |
61 | * install a probe where one is already installed. | |
62 | */ | |
63 | ||
2b144498 SD |
64 | /* serialize (un)register */ |
65 | static struct mutex uprobes_mutex[UPROBES_HASH_SZ]; | |
7b2d81d4 IM |
66 | |
67 | #define uprobes_hash(v) (&uprobes_mutex[((unsigned long)(v)) % UPROBES_HASH_SZ]) | |
2b144498 SD |
68 | |
69 | /* serialize uprobe->pending_list */ | |
70 | static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ]; | |
7b2d81d4 | 71 | #define uprobes_mmap_hash(v) (&uprobes_mmap_mutex[((unsigned long)(v)) % UPROBES_HASH_SZ]) |
2b144498 SD |
72 | |
73 | /* | |
7b2d81d4 | 74 | * uprobe_events allows us to skip the uprobe_mmap if there are no uprobe |
2b144498 SD |
75 | * events active at this time. Probably a fine grained per inode count is |
76 | * better? | |
77 | */ | |
78 | static atomic_t uprobe_events = ATOMIC_INIT(0); | |
79 | ||
3ff54efd SD |
80 | struct uprobe { |
81 | struct rb_node rb_node; /* node in the rb tree */ | |
82 | atomic_t ref; | |
83 | struct rw_semaphore consumer_rwsem; | |
84 | struct list_head pending_list; | |
85 | struct uprobe_consumer *consumers; | |
86 | struct inode *inode; /* Also hold a ref to inode */ | |
87 | loff_t offset; | |
88 | int flags; | |
89 | struct arch_uprobe arch; | |
90 | }; | |
91 | ||
2b144498 SD |
92 | /* |
93 | * valid_vma: Verify if the specified vma is an executable vma | |
94 | * Relax restrictions while unregistering: vm_flags might have | |
95 | * changed after breakpoint was inserted. | |
96 | * - is_register: indicates if we are in register context. | |
97 | * - Return 1 if the specified virtual address is in an | |
98 | * executable vma. | |
99 | */ | |
100 | static bool valid_vma(struct vm_area_struct *vma, bool is_register) | |
101 | { | |
102 | if (!vma->vm_file) | |
103 | return false; | |
104 | ||
105 | if (!is_register) | |
106 | return true; | |
107 | ||
ea131377 ON |
108 | if ((vma->vm_flags & (VM_HUGETLB|VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)) |
109 | == (VM_READ|VM_EXEC)) | |
2b144498 SD |
110 | return true; |
111 | ||
112 | return false; | |
113 | } | |
114 | ||
115 | static loff_t vma_address(struct vm_area_struct *vma, loff_t offset) | |
116 | { | |
117 | loff_t vaddr; | |
118 | ||
119 | vaddr = vma->vm_start + offset; | |
120 | vaddr -= vma->vm_pgoff << PAGE_SHIFT; | |
7b2d81d4 | 121 | |
2b144498 SD |
122 | return vaddr; |
123 | } | |
124 | ||
125 | /** | |
126 | * __replace_page - replace page in vma by new page. | |
127 | * based on replace_page in mm/ksm.c | |
128 | * | |
129 | * @vma: vma that holds the pte pointing to page | |
c517ee74 | 130 | * @addr: address the old @page is mapped at |
2b144498 SD |
131 | * @page: the cowed page we are replacing by kpage |
132 | * @kpage: the modified page we replace page by | |
133 | * | |
134 | * Returns 0 on success, -EFAULT on failure. | |
135 | */ | |
c517ee74 ON |
136 | static int __replace_page(struct vm_area_struct *vma, unsigned long addr, |
137 | struct page *page, struct page *kpage) | |
2b144498 SD |
138 | { |
139 | struct mm_struct *mm = vma->vm_mm; | |
5323ce71 ON |
140 | spinlock_t *ptl; |
141 | pte_t *ptep; | |
2b144498 | 142 | |
5323ce71 | 143 | ptep = page_check_address(page, mm, addr, &ptl, 0); |
2b144498 | 144 | if (!ptep) |
5323ce71 | 145 | return -EAGAIN; |
2b144498 SD |
146 | |
147 | get_page(kpage); | |
148 | page_add_new_anon_rmap(kpage, vma, addr); | |
149 | ||
7396fa81 SD |
150 | if (!PageAnon(page)) { |
151 | dec_mm_counter(mm, MM_FILEPAGES); | |
152 | inc_mm_counter(mm, MM_ANONPAGES); | |
153 | } | |
154 | ||
2b144498 SD |
155 | flush_cache_page(vma, addr, pte_pfn(*ptep)); |
156 | ptep_clear_flush(vma, addr, ptep); | |
157 | set_pte_at_notify(mm, addr, ptep, mk_pte(kpage, vma->vm_page_prot)); | |
158 | ||
159 | page_remove_rmap(page); | |
160 | if (!page_mapped(page)) | |
161 | try_to_free_swap(page); | |
162 | put_page(page); | |
163 | pte_unmap_unlock(ptep, ptl); | |
2b144498 | 164 | |
5323ce71 | 165 | return 0; |
2b144498 SD |
166 | } |
167 | ||
168 | /** | |
5cb4ac3a | 169 | * is_swbp_insn - check if instruction is breakpoint instruction. |
2b144498 | 170 | * @insn: instruction to be checked. |
5cb4ac3a | 171 | * Default implementation of is_swbp_insn |
2b144498 SD |
172 | * Returns true if @insn is a breakpoint instruction. |
173 | */ | |
5cb4ac3a | 174 | bool __weak is_swbp_insn(uprobe_opcode_t *insn) |
2b144498 | 175 | { |
5cb4ac3a | 176 | return *insn == UPROBE_SWBP_INSN; |
2b144498 SD |
177 | } |
178 | ||
179 | /* | |
180 | * NOTE: | |
181 | * Expect the breakpoint instruction to be the smallest size instruction for | |
182 | * the architecture. If an arch has variable length instruction and the | |
183 | * breakpoint instruction is not of the smallest length instruction | |
184 | * supported by that architecture then we need to modify read_opcode / | |
185 | * write_opcode accordingly. This would never be a problem for archs that | |
186 | * have fixed length instructions. | |
187 | */ | |
188 | ||
189 | /* | |
190 | * write_opcode - write the opcode at a given virtual address. | |
e3343e6a | 191 | * @auprobe: arch breakpointing information. |
2b144498 | 192 | * @mm: the probed process address space. |
2b144498 SD |
193 | * @vaddr: the virtual address to store the opcode. |
194 | * @opcode: opcode to be written at @vaddr. | |
195 | * | |
196 | * Called with mm->mmap_sem held (for read and with a reference to | |
197 | * mm). | |
198 | * | |
199 | * For mm @mm, write the opcode at @vaddr. | |
200 | * Return 0 (success) or a negative errno. | |
201 | */ | |
e3343e6a | 202 | static int write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, |
2b144498 SD |
203 | unsigned long vaddr, uprobe_opcode_t opcode) |
204 | { | |
205 | struct page *old_page, *new_page; | |
2b144498 SD |
206 | void *vaddr_old, *vaddr_new; |
207 | struct vm_area_struct *vma; | |
2b144498 | 208 | int ret; |
f403072c | 209 | |
5323ce71 | 210 | retry: |
2b144498 SD |
211 | /* Read the page with vaddr into memory */ |
212 | ret = get_user_pages(NULL, mm, vaddr, 1, 0, 0, &old_page, &vma); | |
213 | if (ret <= 0) | |
214 | return ret; | |
7b2d81d4 | 215 | |
2b144498 SD |
216 | ret = -ENOMEM; |
217 | new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr); | |
218 | if (!new_page) | |
219 | goto put_out; | |
220 | ||
221 | __SetPageUptodate(new_page); | |
222 | ||
223 | /* | |
224 | * lock page will serialize against do_wp_page()'s | |
225 | * PageAnon() handling | |
226 | */ | |
227 | lock_page(old_page); | |
228 | /* copy the page now that we've got it stable */ | |
229 | vaddr_old = kmap_atomic(old_page); | |
230 | vaddr_new = kmap_atomic(new_page); | |
231 | ||
232 | memcpy(vaddr_new, vaddr_old, PAGE_SIZE); | |
d9c4a30e | 233 | memcpy(vaddr_new + (vaddr & ~PAGE_MASK), &opcode, UPROBE_SWBP_INSN_SIZE); |
2b144498 SD |
234 | |
235 | kunmap_atomic(vaddr_new); | |
236 | kunmap_atomic(vaddr_old); | |
237 | ||
238 | ret = anon_vma_prepare(vma); | |
239 | if (ret) | |
240 | goto unlock_out; | |
241 | ||
c517ee74 | 242 | ret = __replace_page(vma, vaddr, old_page, new_page); |
2b144498 SD |
243 | |
244 | unlock_out: | |
245 | unlock_page(old_page); | |
246 | page_cache_release(new_page); | |
247 | ||
248 | put_out: | |
7b2d81d4 IM |
249 | put_page(old_page); |
250 | ||
5323ce71 ON |
251 | if (unlikely(ret == -EAGAIN)) |
252 | goto retry; | |
2b144498 SD |
253 | return ret; |
254 | } | |
255 | ||
256 | /** | |
257 | * read_opcode - read the opcode at a given virtual address. | |
258 | * @mm: the probed process address space. | |
259 | * @vaddr: the virtual address to read the opcode. | |
260 | * @opcode: location to store the read opcode. | |
261 | * | |
262 | * Called with mm->mmap_sem held (for read and with a reference to | |
263 | * mm. | |
264 | * | |
265 | * For mm @mm, read the opcode at @vaddr and store it in @opcode. | |
266 | * Return 0 (success) or a negative errno. | |
267 | */ | |
7b2d81d4 | 268 | static int read_opcode(struct mm_struct *mm, unsigned long vaddr, uprobe_opcode_t *opcode) |
2b144498 SD |
269 | { |
270 | struct page *page; | |
271 | void *vaddr_new; | |
272 | int ret; | |
273 | ||
a3d7bb47 | 274 | ret = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL); |
2b144498 SD |
275 | if (ret <= 0) |
276 | return ret; | |
277 | ||
278 | lock_page(page); | |
279 | vaddr_new = kmap_atomic(page); | |
280 | vaddr &= ~PAGE_MASK; | |
5cb4ac3a | 281 | memcpy(opcode, vaddr_new + vaddr, UPROBE_SWBP_INSN_SIZE); |
2b144498 SD |
282 | kunmap_atomic(vaddr_new); |
283 | unlock_page(page); | |
7b2d81d4 IM |
284 | |
285 | put_page(page); | |
286 | ||
2b144498 SD |
287 | return 0; |
288 | } | |
289 | ||
5cb4ac3a | 290 | static int is_swbp_at_addr(struct mm_struct *mm, unsigned long vaddr) |
2b144498 SD |
291 | { |
292 | uprobe_opcode_t opcode; | |
7b2d81d4 | 293 | int result; |
2b144498 | 294 | |
c00b2750 ON |
295 | if (current->mm == mm) { |
296 | pagefault_disable(); | |
297 | result = __copy_from_user_inatomic(&opcode, (void __user*)vaddr, | |
298 | sizeof(opcode)); | |
299 | pagefault_enable(); | |
300 | ||
301 | if (likely(result == 0)) | |
302 | goto out; | |
303 | } | |
304 | ||
7b2d81d4 | 305 | result = read_opcode(mm, vaddr, &opcode); |
2b144498 SD |
306 | if (result) |
307 | return result; | |
c00b2750 | 308 | out: |
5cb4ac3a | 309 | if (is_swbp_insn(&opcode)) |
2b144498 SD |
310 | return 1; |
311 | ||
312 | return 0; | |
313 | } | |
314 | ||
315 | /** | |
5cb4ac3a | 316 | * set_swbp - store breakpoint at a given address. |
e3343e6a | 317 | * @auprobe: arch specific probepoint information. |
2b144498 | 318 | * @mm: the probed process address space. |
2b144498 SD |
319 | * @vaddr: the virtual address to insert the opcode. |
320 | * | |
321 | * For mm @mm, store the breakpoint instruction at @vaddr. | |
322 | * Return 0 (success) or a negative errno. | |
323 | */ | |
5cb4ac3a | 324 | int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) |
2b144498 | 325 | { |
7b2d81d4 | 326 | int result; |
c5784de2 PZ |
327 | /* |
328 | * See the comment near uprobes_hash(). | |
329 | */ | |
5cb4ac3a | 330 | result = is_swbp_at_addr(mm, vaddr); |
2b144498 SD |
331 | if (result == 1) |
332 | return -EEXIST; | |
333 | ||
334 | if (result) | |
335 | return result; | |
336 | ||
5cb4ac3a | 337 | return write_opcode(auprobe, mm, vaddr, UPROBE_SWBP_INSN); |
2b144498 SD |
338 | } |
339 | ||
340 | /** | |
341 | * set_orig_insn - Restore the original instruction. | |
342 | * @mm: the probed process address space. | |
e3343e6a | 343 | * @auprobe: arch specific probepoint information. |
2b144498 SD |
344 | * @vaddr: the virtual address to insert the opcode. |
345 | * @verify: if true, verify existance of breakpoint instruction. | |
346 | * | |
347 | * For mm @mm, restore the original opcode (opcode) at @vaddr. | |
348 | * Return 0 (success) or a negative errno. | |
349 | */ | |
7b2d81d4 | 350 | int __weak |
e3343e6a | 351 | set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr, bool verify) |
2b144498 SD |
352 | { |
353 | if (verify) { | |
7b2d81d4 | 354 | int result; |
2b144498 | 355 | |
5cb4ac3a | 356 | result = is_swbp_at_addr(mm, vaddr); |
2b144498 SD |
357 | if (!result) |
358 | return -EINVAL; | |
359 | ||
360 | if (result != 1) | |
361 | return result; | |
362 | } | |
e3343e6a | 363 | return write_opcode(auprobe, mm, vaddr, *(uprobe_opcode_t *)auprobe->insn); |
2b144498 SD |
364 | } |
365 | ||
366 | static int match_uprobe(struct uprobe *l, struct uprobe *r) | |
367 | { | |
368 | if (l->inode < r->inode) | |
369 | return -1; | |
7b2d81d4 | 370 | |
2b144498 SD |
371 | if (l->inode > r->inode) |
372 | return 1; | |
2b144498 | 373 | |
7b2d81d4 IM |
374 | if (l->offset < r->offset) |
375 | return -1; | |
376 | ||
377 | if (l->offset > r->offset) | |
378 | return 1; | |
2b144498 SD |
379 | |
380 | return 0; | |
381 | } | |
382 | ||
383 | static struct uprobe *__find_uprobe(struct inode *inode, loff_t offset) | |
384 | { | |
385 | struct uprobe u = { .inode = inode, .offset = offset }; | |
386 | struct rb_node *n = uprobes_tree.rb_node; | |
387 | struct uprobe *uprobe; | |
388 | int match; | |
389 | ||
390 | while (n) { | |
391 | uprobe = rb_entry(n, struct uprobe, rb_node); | |
392 | match = match_uprobe(&u, uprobe); | |
393 | if (!match) { | |
394 | atomic_inc(&uprobe->ref); | |
395 | return uprobe; | |
396 | } | |
7b2d81d4 | 397 | |
2b144498 SD |
398 | if (match < 0) |
399 | n = n->rb_left; | |
400 | else | |
401 | n = n->rb_right; | |
402 | } | |
403 | return NULL; | |
404 | } | |
405 | ||
406 | /* | |
407 | * Find a uprobe corresponding to a given inode:offset | |
408 | * Acquires uprobes_treelock | |
409 | */ | |
410 | static struct uprobe *find_uprobe(struct inode *inode, loff_t offset) | |
411 | { | |
412 | struct uprobe *uprobe; | |
413 | unsigned long flags; | |
414 | ||
415 | spin_lock_irqsave(&uprobes_treelock, flags); | |
416 | uprobe = __find_uprobe(inode, offset); | |
417 | spin_unlock_irqrestore(&uprobes_treelock, flags); | |
7b2d81d4 | 418 | |
2b144498 SD |
419 | return uprobe; |
420 | } | |
421 | ||
422 | static struct uprobe *__insert_uprobe(struct uprobe *uprobe) | |
423 | { | |
424 | struct rb_node **p = &uprobes_tree.rb_node; | |
425 | struct rb_node *parent = NULL; | |
426 | struct uprobe *u; | |
427 | int match; | |
428 | ||
429 | while (*p) { | |
430 | parent = *p; | |
431 | u = rb_entry(parent, struct uprobe, rb_node); | |
432 | match = match_uprobe(uprobe, u); | |
433 | if (!match) { | |
434 | atomic_inc(&u->ref); | |
435 | return u; | |
436 | } | |
437 | ||
438 | if (match < 0) | |
439 | p = &parent->rb_left; | |
440 | else | |
441 | p = &parent->rb_right; | |
442 | ||
443 | } | |
7b2d81d4 | 444 | |
2b144498 SD |
445 | u = NULL; |
446 | rb_link_node(&uprobe->rb_node, parent, p); | |
447 | rb_insert_color(&uprobe->rb_node, &uprobes_tree); | |
448 | /* get access + creation ref */ | |
449 | atomic_set(&uprobe->ref, 2); | |
7b2d81d4 | 450 | |
2b144498 SD |
451 | return u; |
452 | } | |
453 | ||
454 | /* | |
7b2d81d4 | 455 | * Acquire uprobes_treelock. |
2b144498 SD |
456 | * Matching uprobe already exists in rbtree; |
457 | * increment (access refcount) and return the matching uprobe. | |
458 | * | |
459 | * No matching uprobe; insert the uprobe in rb_tree; | |
460 | * get a double refcount (access + creation) and return NULL. | |
461 | */ | |
462 | static struct uprobe *insert_uprobe(struct uprobe *uprobe) | |
463 | { | |
464 | unsigned long flags; | |
465 | struct uprobe *u; | |
466 | ||
467 | spin_lock_irqsave(&uprobes_treelock, flags); | |
468 | u = __insert_uprobe(uprobe); | |
469 | spin_unlock_irqrestore(&uprobes_treelock, flags); | |
7b2d81d4 | 470 | |
0326f5a9 SD |
471 | /* For now assume that the instruction need not be single-stepped */ |
472 | uprobe->flags |= UPROBE_SKIP_SSTEP; | |
473 | ||
2b144498 SD |
474 | return u; |
475 | } | |
476 | ||
477 | static void put_uprobe(struct uprobe *uprobe) | |
478 | { | |
479 | if (atomic_dec_and_test(&uprobe->ref)) | |
480 | kfree(uprobe); | |
481 | } | |
482 | ||
483 | static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) | |
484 | { | |
485 | struct uprobe *uprobe, *cur_uprobe; | |
486 | ||
487 | uprobe = kzalloc(sizeof(struct uprobe), GFP_KERNEL); | |
488 | if (!uprobe) | |
489 | return NULL; | |
490 | ||
491 | uprobe->inode = igrab(inode); | |
492 | uprobe->offset = offset; | |
493 | init_rwsem(&uprobe->consumer_rwsem); | |
2b144498 SD |
494 | |
495 | /* add to uprobes_tree, sorted on inode:offset */ | |
496 | cur_uprobe = insert_uprobe(uprobe); | |
497 | ||
498 | /* a uprobe exists for this inode:offset combination */ | |
499 | if (cur_uprobe) { | |
500 | kfree(uprobe); | |
501 | uprobe = cur_uprobe; | |
502 | iput(inode); | |
7b2d81d4 | 503 | } else { |
2b144498 | 504 | atomic_inc(&uprobe_events); |
7b2d81d4 IM |
505 | } |
506 | ||
2b144498 SD |
507 | return uprobe; |
508 | } | |
509 | ||
0326f5a9 SD |
510 | static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs) |
511 | { | |
512 | struct uprobe_consumer *uc; | |
513 | ||
514 | if (!(uprobe->flags & UPROBE_RUN_HANDLER)) | |
515 | return; | |
516 | ||
517 | down_read(&uprobe->consumer_rwsem); | |
518 | for (uc = uprobe->consumers; uc; uc = uc->next) { | |
519 | if (!uc->filter || uc->filter(uc, current)) | |
520 | uc->handler(uc, regs); | |
521 | } | |
522 | up_read(&uprobe->consumer_rwsem); | |
523 | } | |
524 | ||
2b144498 | 525 | /* Returns the previous consumer */ |
7b2d81d4 | 526 | static struct uprobe_consumer * |
e3343e6a | 527 | consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc) |
2b144498 SD |
528 | { |
529 | down_write(&uprobe->consumer_rwsem); | |
e3343e6a SD |
530 | uc->next = uprobe->consumers; |
531 | uprobe->consumers = uc; | |
2b144498 | 532 | up_write(&uprobe->consumer_rwsem); |
7b2d81d4 | 533 | |
e3343e6a | 534 | return uc->next; |
2b144498 SD |
535 | } |
536 | ||
537 | /* | |
e3343e6a SD |
538 | * For uprobe @uprobe, delete the consumer @uc. |
539 | * Return true if the @uc is deleted successfully | |
2b144498 SD |
540 | * or return false. |
541 | */ | |
e3343e6a | 542 | static bool consumer_del(struct uprobe *uprobe, struct uprobe_consumer *uc) |
2b144498 SD |
543 | { |
544 | struct uprobe_consumer **con; | |
545 | bool ret = false; | |
546 | ||
547 | down_write(&uprobe->consumer_rwsem); | |
548 | for (con = &uprobe->consumers; *con; con = &(*con)->next) { | |
e3343e6a SD |
549 | if (*con == uc) { |
550 | *con = uc->next; | |
2b144498 SD |
551 | ret = true; |
552 | break; | |
553 | } | |
554 | } | |
555 | up_write(&uprobe->consumer_rwsem); | |
7b2d81d4 | 556 | |
2b144498 SD |
557 | return ret; |
558 | } | |
559 | ||
e3343e6a | 560 | static int |
d436615e | 561 | __copy_insn(struct address_space *mapping, struct file *filp, char *insn, |
593609a5 | 562 | unsigned long nbytes, loff_t offset) |
2b144498 | 563 | { |
2b144498 SD |
564 | struct page *page; |
565 | void *vaddr; | |
593609a5 ON |
566 | unsigned long off; |
567 | pgoff_t idx; | |
2b144498 SD |
568 | |
569 | if (!filp) | |
570 | return -EINVAL; | |
571 | ||
cc359d18 ON |
572 | if (!mapping->a_ops->readpage) |
573 | return -EIO; | |
574 | ||
593609a5 ON |
575 | idx = offset >> PAGE_CACHE_SHIFT; |
576 | off = offset & ~PAGE_MASK; | |
2b144498 SD |
577 | |
578 | /* | |
579 | * Ensure that the page that has the original instruction is | |
580 | * populated and in page-cache. | |
581 | */ | |
582 | page = read_mapping_page(mapping, idx, filp); | |
583 | if (IS_ERR(page)) | |
584 | return PTR_ERR(page); | |
585 | ||
586 | vaddr = kmap_atomic(page); | |
593609a5 | 587 | memcpy(insn, vaddr + off, nbytes); |
2b144498 SD |
588 | kunmap_atomic(vaddr); |
589 | page_cache_release(page); | |
7b2d81d4 | 590 | |
2b144498 SD |
591 | return 0; |
592 | } | |
593 | ||
d436615e | 594 | static int copy_insn(struct uprobe *uprobe, struct file *filp) |
2b144498 SD |
595 | { |
596 | struct address_space *mapping; | |
2b144498 | 597 | unsigned long nbytes; |
7b2d81d4 | 598 | int bytes; |
2b144498 | 599 | |
d436615e | 600 | nbytes = PAGE_SIZE - (uprobe->offset & ~PAGE_MASK); |
2b144498 SD |
601 | mapping = uprobe->inode->i_mapping; |
602 | ||
603 | /* Instruction at end of binary; copy only available bytes */ | |
604 | if (uprobe->offset + MAX_UINSN_BYTES > uprobe->inode->i_size) | |
605 | bytes = uprobe->inode->i_size - uprobe->offset; | |
606 | else | |
607 | bytes = MAX_UINSN_BYTES; | |
608 | ||
609 | /* Instruction at the page-boundary; copy bytes in second page */ | |
610 | if (nbytes < bytes) { | |
fc36f595 ON |
611 | int err = __copy_insn(mapping, filp, uprobe->arch.insn + nbytes, |
612 | bytes - nbytes, uprobe->offset + nbytes); | |
613 | if (err) | |
614 | return err; | |
2b144498 SD |
615 | bytes = nbytes; |
616 | } | |
d436615e | 617 | return __copy_insn(mapping, filp, uprobe->arch.insn, bytes, uprobe->offset); |
2b144498 SD |
618 | } |
619 | ||
682968e0 SD |
620 | /* |
621 | * How mm->uprobes_state.count gets updated | |
622 | * uprobe_mmap() increments the count if | |
623 | * - it successfully adds a breakpoint. | |
624 | * - it cannot add a breakpoint, but sees that there is a underlying | |
625 | * breakpoint (via a is_swbp_at_addr()). | |
626 | * | |
627 | * uprobe_munmap() decrements the count if | |
628 | * - it sees a underlying breakpoint, (via is_swbp_at_addr) | |
629 | * (Subsequent uprobe_unregister wouldnt find the breakpoint | |
630 | * unless a uprobe_mmap kicks in, since the old vma would be | |
631 | * dropped just after uprobe_munmap.) | |
632 | * | |
633 | * uprobe_register increments the count if: | |
634 | * - it successfully adds a breakpoint. | |
635 | * | |
636 | * uprobe_unregister decrements the count if: | |
637 | * - it sees a underlying breakpoint and removes successfully. | |
638 | * (via is_swbp_at_addr) | |
639 | * (Subsequent uprobe_munmap wouldnt find the breakpoint | |
640 | * since there is no underlying breakpoint after the | |
641 | * breakpoint removal.) | |
642 | */ | |
e3343e6a SD |
643 | static int |
644 | install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, | |
816c03fb | 645 | struct vm_area_struct *vma, unsigned long vaddr) |
2b144498 | 646 | { |
2b144498 SD |
647 | int ret; |
648 | ||
649 | /* | |
650 | * If probe is being deleted, unregister thread could be done with | |
651 | * the vma-rmap-walk through. Adding a probe now can be fatal since | |
652 | * nobody will be able to cleanup. Also we could be from fork or | |
653 | * mremap path, where the probe might have already been inserted. | |
654 | * Hence behave as if probe already existed. | |
655 | */ | |
656 | if (!uprobe->consumers) | |
657 | return -EEXIST; | |
658 | ||
900771a4 | 659 | if (!(uprobe->flags & UPROBE_COPY_INSN)) { |
d436615e | 660 | ret = copy_insn(uprobe, vma->vm_file); |
2b144498 SD |
661 | if (ret) |
662 | return ret; | |
663 | ||
5cb4ac3a | 664 | if (is_swbp_insn((uprobe_opcode_t *)uprobe->arch.insn)) |
c1914a09 | 665 | return -ENOTSUPP; |
2b144498 | 666 | |
816c03fb | 667 | ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, vaddr); |
2b144498 SD |
668 | if (ret) |
669 | return ret; | |
670 | ||
d9c4a30e ON |
671 | /* write_opcode() assumes we don't cross page boundary */ |
672 | BUG_ON((uprobe->offset & ~PAGE_MASK) + | |
673 | UPROBE_SWBP_INSN_SIZE > PAGE_SIZE); | |
674 | ||
900771a4 | 675 | uprobe->flags |= UPROBE_COPY_INSN; |
2b144498 | 676 | } |
682968e0 SD |
677 | |
678 | /* | |
679 | * Ideally, should be updating the probe count after the breakpoint | |
680 | * has been successfully inserted. However a thread could hit the | |
681 | * breakpoint we just inserted even before the probe count is | |
682 | * incremented. If this is the first breakpoint placed, breakpoint | |
683 | * notifier might ignore uprobes and pass the trap to the thread. | |
684 | * Hence increment before and decrement on failure. | |
685 | */ | |
686 | atomic_inc(&mm->uprobes_state.count); | |
816c03fb | 687 | ret = set_swbp(&uprobe->arch, mm, vaddr); |
682968e0 SD |
688 | if (ret) |
689 | atomic_dec(&mm->uprobes_state.count); | |
2b144498 SD |
690 | |
691 | return ret; | |
692 | } | |
693 | ||
e3343e6a | 694 | static void |
816c03fb | 695 | remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr) |
2b144498 | 696 | { |
816c03fb | 697 | if (!set_orig_insn(&uprobe->arch, mm, vaddr, true)) |
682968e0 | 698 | atomic_dec(&mm->uprobes_state.count); |
2b144498 SD |
699 | } |
700 | ||
0326f5a9 | 701 | /* |
778b032d ON |
702 | * There could be threads that have already hit the breakpoint. They |
703 | * will recheck the current insn and restart if find_uprobe() fails. | |
704 | * See find_active_uprobe(). | |
0326f5a9 | 705 | */ |
2b144498 SD |
706 | static void delete_uprobe(struct uprobe *uprobe) |
707 | { | |
708 | unsigned long flags; | |
709 | ||
710 | spin_lock_irqsave(&uprobes_treelock, flags); | |
711 | rb_erase(&uprobe->rb_node, &uprobes_tree); | |
712 | spin_unlock_irqrestore(&uprobes_treelock, flags); | |
713 | iput(uprobe->inode); | |
714 | put_uprobe(uprobe); | |
715 | atomic_dec(&uprobe_events); | |
716 | } | |
717 | ||
26872090 ON |
718 | struct map_info { |
719 | struct map_info *next; | |
720 | struct mm_struct *mm; | |
816c03fb | 721 | unsigned long vaddr; |
26872090 ON |
722 | }; |
723 | ||
724 | static inline struct map_info *free_map_info(struct map_info *info) | |
2b144498 | 725 | { |
26872090 ON |
726 | struct map_info *next = info->next; |
727 | kfree(info); | |
728 | return next; | |
729 | } | |
730 | ||
731 | static struct map_info * | |
732 | build_map_info(struct address_space *mapping, loff_t offset, bool is_register) | |
733 | { | |
734 | unsigned long pgoff = offset >> PAGE_SHIFT; | |
2b144498 SD |
735 | struct prio_tree_iter iter; |
736 | struct vm_area_struct *vma; | |
26872090 ON |
737 | struct map_info *curr = NULL; |
738 | struct map_info *prev = NULL; | |
739 | struct map_info *info; | |
740 | int more = 0; | |
2b144498 | 741 | |
26872090 ON |
742 | again: |
743 | mutex_lock(&mapping->i_mmap_mutex); | |
2b144498 SD |
744 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { |
745 | if (!valid_vma(vma, is_register)) | |
746 | continue; | |
747 | ||
7a5bfb66 ON |
748 | if (!prev && !more) { |
749 | /* | |
750 | * Needs GFP_NOWAIT to avoid i_mmap_mutex recursion through | |
751 | * reclaim. This is optimistic, no harm done if it fails. | |
752 | */ | |
753 | prev = kmalloc(sizeof(struct map_info), | |
754 | GFP_NOWAIT | __GFP_NOMEMALLOC | __GFP_NOWARN); | |
755 | if (prev) | |
756 | prev->next = NULL; | |
757 | } | |
26872090 ON |
758 | if (!prev) { |
759 | more++; | |
760 | continue; | |
2b144498 | 761 | } |
2b144498 | 762 | |
26872090 ON |
763 | if (!atomic_inc_not_zero(&vma->vm_mm->mm_users)) |
764 | continue; | |
7b2d81d4 | 765 | |
26872090 ON |
766 | info = prev; |
767 | prev = prev->next; | |
768 | info->next = curr; | |
769 | curr = info; | |
2b144498 | 770 | |
26872090 ON |
771 | info->mm = vma->vm_mm; |
772 | info->vaddr = vma_address(vma, offset); | |
773 | } | |
2b144498 SD |
774 | mutex_unlock(&mapping->i_mmap_mutex); |
775 | ||
26872090 ON |
776 | if (!more) |
777 | goto out; | |
778 | ||
779 | prev = curr; | |
780 | while (curr) { | |
781 | mmput(curr->mm); | |
782 | curr = curr->next; | |
783 | } | |
7b2d81d4 | 784 | |
26872090 ON |
785 | do { |
786 | info = kmalloc(sizeof(struct map_info), GFP_KERNEL); | |
787 | if (!info) { | |
788 | curr = ERR_PTR(-ENOMEM); | |
789 | goto out; | |
790 | } | |
791 | info->next = prev; | |
792 | prev = info; | |
793 | } while (--more); | |
794 | ||
795 | goto again; | |
796 | out: | |
797 | while (prev) | |
798 | prev = free_map_info(prev); | |
799 | return curr; | |
2b144498 SD |
800 | } |
801 | ||
802 | static int register_for_each_vma(struct uprobe *uprobe, bool is_register) | |
803 | { | |
26872090 ON |
804 | struct map_info *info; |
805 | int err = 0; | |
2b144498 | 806 | |
26872090 ON |
807 | info = build_map_info(uprobe->inode->i_mapping, |
808 | uprobe->offset, is_register); | |
809 | if (IS_ERR(info)) | |
810 | return PTR_ERR(info); | |
7b2d81d4 | 811 | |
26872090 ON |
812 | while (info) { |
813 | struct mm_struct *mm = info->mm; | |
814 | struct vm_area_struct *vma; | |
7b2d81d4 | 815 | |
26872090 ON |
816 | if (err) |
817 | goto free; | |
7b2d81d4 | 818 | |
77fc4af1 | 819 | down_write(&mm->mmap_sem); |
26872090 ON |
820 | vma = find_vma(mm, (unsigned long)info->vaddr); |
821 | if (!vma || !valid_vma(vma, is_register)) | |
822 | goto unlock; | |
823 | ||
2b144498 | 824 | if (vma->vm_file->f_mapping->host != uprobe->inode || |
816c03fb | 825 | vma_address(vma, uprobe->offset) != info->vaddr) |
26872090 | 826 | goto unlock; |
2b144498 | 827 | |
2b144498 | 828 | if (is_register) { |
26872090 | 829 | err = install_breakpoint(uprobe, mm, vma, info->vaddr); |
c5784de2 PZ |
830 | /* |
831 | * We can race against uprobe_mmap(), see the | |
832 | * comment near uprobe_hash(). | |
833 | */ | |
26872090 ON |
834 | if (err == -EEXIST) |
835 | err = 0; | |
836 | } else { | |
837 | remove_breakpoint(uprobe, mm, info->vaddr); | |
2b144498 | 838 | } |
26872090 ON |
839 | unlock: |
840 | up_write(&mm->mmap_sem); | |
841 | free: | |
842 | mmput(mm); | |
843 | info = free_map_info(info); | |
2b144498 | 844 | } |
7b2d81d4 | 845 | |
26872090 | 846 | return err; |
2b144498 SD |
847 | } |
848 | ||
7b2d81d4 | 849 | static int __uprobe_register(struct uprobe *uprobe) |
2b144498 SD |
850 | { |
851 | return register_for_each_vma(uprobe, true); | |
852 | } | |
853 | ||
7b2d81d4 | 854 | static void __uprobe_unregister(struct uprobe *uprobe) |
2b144498 SD |
855 | { |
856 | if (!register_for_each_vma(uprobe, false)) | |
857 | delete_uprobe(uprobe); | |
858 | ||
859 | /* TODO : cant unregister? schedule a worker thread */ | |
860 | } | |
861 | ||
862 | /* | |
7b2d81d4 | 863 | * uprobe_register - register a probe |
2b144498 SD |
864 | * @inode: the file in which the probe has to be placed. |
865 | * @offset: offset from the start of the file. | |
e3343e6a | 866 | * @uc: information on howto handle the probe.. |
2b144498 | 867 | * |
7b2d81d4 | 868 | * Apart from the access refcount, uprobe_register() takes a creation |
2b144498 SD |
869 | * refcount (thro alloc_uprobe) if and only if this @uprobe is getting |
870 | * inserted into the rbtree (i.e first consumer for a @inode:@offset | |
7b2d81d4 | 871 | * tuple). Creation refcount stops uprobe_unregister from freeing the |
2b144498 | 872 | * @uprobe even before the register operation is complete. Creation |
e3343e6a | 873 | * refcount is released when the last @uc for the @uprobe |
2b144498 SD |
874 | * unregisters. |
875 | * | |
876 | * Return errno if it cannot successully install probes | |
877 | * else return 0 (success) | |
878 | */ | |
e3343e6a | 879 | int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) |
2b144498 SD |
880 | { |
881 | struct uprobe *uprobe; | |
7b2d81d4 | 882 | int ret; |
2b144498 | 883 | |
e3343e6a | 884 | if (!inode || !uc || uc->next) |
7b2d81d4 | 885 | return -EINVAL; |
2b144498 SD |
886 | |
887 | if (offset > i_size_read(inode)) | |
7b2d81d4 | 888 | return -EINVAL; |
2b144498 SD |
889 | |
890 | ret = 0; | |
891 | mutex_lock(uprobes_hash(inode)); | |
892 | uprobe = alloc_uprobe(inode, offset); | |
7b2d81d4 | 893 | |
e3343e6a | 894 | if (uprobe && !consumer_add(uprobe, uc)) { |
7b2d81d4 | 895 | ret = __uprobe_register(uprobe); |
2b144498 SD |
896 | if (ret) { |
897 | uprobe->consumers = NULL; | |
7b2d81d4 IM |
898 | __uprobe_unregister(uprobe); |
899 | } else { | |
900771a4 | 900 | uprobe->flags |= UPROBE_RUN_HANDLER; |
7b2d81d4 | 901 | } |
2b144498 SD |
902 | } |
903 | ||
904 | mutex_unlock(uprobes_hash(inode)); | |
905 | put_uprobe(uprobe); | |
906 | ||
907 | return ret; | |
908 | } | |
909 | ||
910 | /* | |
7b2d81d4 | 911 | * uprobe_unregister - unregister a already registered probe. |
2b144498 SD |
912 | * @inode: the file in which the probe has to be removed. |
913 | * @offset: offset from the start of the file. | |
e3343e6a | 914 | * @uc: identify which probe if multiple probes are colocated. |
2b144498 | 915 | */ |
e3343e6a | 916 | void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) |
2b144498 | 917 | { |
7b2d81d4 | 918 | struct uprobe *uprobe; |
2b144498 | 919 | |
e3343e6a | 920 | if (!inode || !uc) |
2b144498 SD |
921 | return; |
922 | ||
923 | uprobe = find_uprobe(inode, offset); | |
924 | if (!uprobe) | |
925 | return; | |
926 | ||
927 | mutex_lock(uprobes_hash(inode)); | |
2b144498 | 928 | |
e3343e6a | 929 | if (consumer_del(uprobe, uc)) { |
7b2d81d4 IM |
930 | if (!uprobe->consumers) { |
931 | __uprobe_unregister(uprobe); | |
900771a4 | 932 | uprobe->flags &= ~UPROBE_RUN_HANDLER; |
7b2d81d4 | 933 | } |
2b144498 SD |
934 | } |
935 | ||
2b144498 SD |
936 | mutex_unlock(uprobes_hash(inode)); |
937 | if (uprobe) | |
938 | put_uprobe(uprobe); | |
939 | } | |
940 | ||
941 | /* | |
942 | * Of all the nodes that correspond to the given inode, return the node | |
943 | * with the least offset. | |
944 | */ | |
945 | static struct rb_node *find_least_offset_node(struct inode *inode) | |
946 | { | |
947 | struct uprobe u = { .inode = inode, .offset = 0}; | |
948 | struct rb_node *n = uprobes_tree.rb_node; | |
949 | struct rb_node *close_node = NULL; | |
950 | struct uprobe *uprobe; | |
951 | int match; | |
952 | ||
953 | while (n) { | |
954 | uprobe = rb_entry(n, struct uprobe, rb_node); | |
955 | match = match_uprobe(&u, uprobe); | |
7b2d81d4 | 956 | |
2b144498 SD |
957 | if (uprobe->inode == inode) |
958 | close_node = n; | |
959 | ||
960 | if (!match) | |
961 | return close_node; | |
962 | ||
963 | if (match < 0) | |
964 | n = n->rb_left; | |
965 | else | |
966 | n = n->rb_right; | |
967 | } | |
7b2d81d4 | 968 | |
2b144498 SD |
969 | return close_node; |
970 | } | |
971 | ||
972 | /* | |
973 | * For a given inode, build a list of probes that need to be inserted. | |
974 | */ | |
975 | static void build_probe_list(struct inode *inode, struct list_head *head) | |
976 | { | |
977 | struct uprobe *uprobe; | |
2b144498 | 978 | unsigned long flags; |
7b2d81d4 | 979 | struct rb_node *n; |
2b144498 SD |
980 | |
981 | spin_lock_irqsave(&uprobes_treelock, flags); | |
7b2d81d4 | 982 | |
2b144498 | 983 | n = find_least_offset_node(inode); |
7b2d81d4 | 984 | |
2b144498 SD |
985 | for (; n; n = rb_next(n)) { |
986 | uprobe = rb_entry(n, struct uprobe, rb_node); | |
987 | if (uprobe->inode != inode) | |
988 | break; | |
989 | ||
990 | list_add(&uprobe->pending_list, head); | |
991 | atomic_inc(&uprobe->ref); | |
992 | } | |
7b2d81d4 | 993 | |
2b144498 SD |
994 | spin_unlock_irqrestore(&uprobes_treelock, flags); |
995 | } | |
996 | ||
997 | /* | |
998 | * Called from mmap_region. | |
999 | * called with mm->mmap_sem acquired. | |
1000 | * | |
1001 | * Return -ve no if we fail to insert probes and we cannot | |
1002 | * bail-out. | |
7b2d81d4 IM |
1003 | * Return 0 otherwise. i.e: |
1004 | * | |
2b144498 SD |
1005 | * - successful insertion of probes |
1006 | * - (or) no possible probes to be inserted. | |
1007 | * - (or) insertion of probes failed but we can bail-out. | |
1008 | */ | |
7b2d81d4 | 1009 | int uprobe_mmap(struct vm_area_struct *vma) |
2b144498 SD |
1010 | { |
1011 | struct list_head tmp_list; | |
449d0d7c | 1012 | struct uprobe *uprobe; |
2b144498 | 1013 | struct inode *inode; |
682968e0 | 1014 | int ret, count; |
2b144498 SD |
1015 | |
1016 | if (!atomic_read(&uprobe_events) || !valid_vma(vma, true)) | |
7b2d81d4 | 1017 | return 0; |
2b144498 SD |
1018 | |
1019 | inode = vma->vm_file->f_mapping->host; | |
1020 | if (!inode) | |
7b2d81d4 | 1021 | return 0; |
2b144498 SD |
1022 | |
1023 | INIT_LIST_HEAD(&tmp_list); | |
1024 | mutex_lock(uprobes_mmap_hash(inode)); | |
1025 | build_probe_list(inode, &tmp_list); | |
7b2d81d4 IM |
1026 | |
1027 | ret = 0; | |
682968e0 | 1028 | count = 0; |
7b2d81d4 | 1029 | |
449d0d7c | 1030 | list_for_each_entry(uprobe, &tmp_list, pending_list) { |
2b144498 | 1031 | if (!ret) { |
816c03fb | 1032 | loff_t vaddr = vma_address(vma, uprobe->offset); |
682968e0 SD |
1033 | |
1034 | if (vaddr < vma->vm_start || vaddr >= vma->vm_end) { | |
1035 | put_uprobe(uprobe); | |
1036 | continue; | |
2b144498 | 1037 | } |
682968e0 SD |
1038 | |
1039 | ret = install_breakpoint(uprobe, vma->vm_mm, vma, vaddr); | |
c5784de2 PZ |
1040 | /* |
1041 | * We can race against uprobe_register(), see the | |
1042 | * comment near uprobe_hash(). | |
1043 | */ | |
682968e0 SD |
1044 | if (ret == -EEXIST) { |
1045 | ret = 0; | |
1046 | ||
1047 | if (!is_swbp_at_addr(vma->vm_mm, vaddr)) | |
1048 | continue; | |
1049 | ||
1050 | /* | |
1051 | * Unable to insert a breakpoint, but | |
1052 | * breakpoint lies underneath. Increment the | |
1053 | * probe count. | |
1054 | */ | |
1055 | atomic_inc(&vma->vm_mm->uprobes_state.count); | |
1056 | } | |
1057 | ||
1058 | if (!ret) | |
1059 | count++; | |
2b144498 SD |
1060 | } |
1061 | put_uprobe(uprobe); | |
1062 | } | |
1063 | ||
1064 | mutex_unlock(uprobes_mmap_hash(inode)); | |
1065 | ||
682968e0 SD |
1066 | if (ret) |
1067 | atomic_sub(count, &vma->vm_mm->uprobes_state.count); | |
1068 | ||
2b144498 SD |
1069 | return ret; |
1070 | } | |
1071 | ||
682968e0 SD |
1072 | /* |
1073 | * Called in context of a munmap of a vma. | |
1074 | */ | |
cbc91f71 | 1075 | void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end) |
682968e0 SD |
1076 | { |
1077 | struct list_head tmp_list; | |
449d0d7c | 1078 | struct uprobe *uprobe; |
682968e0 SD |
1079 | struct inode *inode; |
1080 | ||
1081 | if (!atomic_read(&uprobe_events) || !valid_vma(vma, false)) | |
1082 | return; | |
1083 | ||
1084 | if (!atomic_read(&vma->vm_mm->uprobes_state.count)) | |
1085 | return; | |
1086 | ||
1087 | inode = vma->vm_file->f_mapping->host; | |
1088 | if (!inode) | |
1089 | return; | |
1090 | ||
1091 | INIT_LIST_HEAD(&tmp_list); | |
1092 | mutex_lock(uprobes_mmap_hash(inode)); | |
1093 | build_probe_list(inode, &tmp_list); | |
1094 | ||
449d0d7c | 1095 | list_for_each_entry(uprobe, &tmp_list, pending_list) { |
816c03fb | 1096 | loff_t vaddr = vma_address(vma, uprobe->offset); |
682968e0 | 1097 | |
cbc91f71 | 1098 | if (vaddr >= start && vaddr < end) { |
682968e0 SD |
1099 | /* |
1100 | * An unregister could have removed the probe before | |
1101 | * unmap. So check before we decrement the count. | |
1102 | */ | |
1103 | if (is_swbp_at_addr(vma->vm_mm, vaddr) == 1) | |
1104 | atomic_dec(&vma->vm_mm->uprobes_state.count); | |
1105 | } | |
1106 | put_uprobe(uprobe); | |
1107 | } | |
1108 | mutex_unlock(uprobes_mmap_hash(inode)); | |
1109 | } | |
1110 | ||
d4b3b638 SD |
1111 | /* Slot allocation for XOL */ |
1112 | static int xol_add_vma(struct xol_area *area) | |
1113 | { | |
1114 | struct mm_struct *mm; | |
1115 | int ret; | |
1116 | ||
1117 | area->page = alloc_page(GFP_HIGHUSER); | |
1118 | if (!area->page) | |
1119 | return -ENOMEM; | |
1120 | ||
1121 | ret = -EALREADY; | |
1122 | mm = current->mm; | |
1123 | ||
1124 | down_write(&mm->mmap_sem); | |
1125 | if (mm->uprobes_state.xol_area) | |
1126 | goto fail; | |
1127 | ||
1128 | ret = -ENOMEM; | |
1129 | ||
1130 | /* Try to map as high as possible, this is only a hint. */ | |
1131 | area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE, PAGE_SIZE, 0, 0); | |
1132 | if (area->vaddr & ~PAGE_MASK) { | |
1133 | ret = area->vaddr; | |
1134 | goto fail; | |
1135 | } | |
1136 | ||
1137 | ret = install_special_mapping(mm, area->vaddr, PAGE_SIZE, | |
1138 | VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO, &area->page); | |
1139 | if (ret) | |
1140 | goto fail; | |
1141 | ||
1142 | smp_wmb(); /* pairs with get_xol_area() */ | |
1143 | mm->uprobes_state.xol_area = area; | |
1144 | ret = 0; | |
1145 | ||
1146 | fail: | |
1147 | up_write(&mm->mmap_sem); | |
1148 | if (ret) | |
1149 | __free_page(area->page); | |
1150 | ||
1151 | return ret; | |
1152 | } | |
1153 | ||
1154 | static struct xol_area *get_xol_area(struct mm_struct *mm) | |
1155 | { | |
1156 | struct xol_area *area; | |
1157 | ||
1158 | area = mm->uprobes_state.xol_area; | |
1159 | smp_read_barrier_depends(); /* pairs with wmb in xol_add_vma() */ | |
1160 | ||
1161 | return area; | |
1162 | } | |
1163 | ||
1164 | /* | |
1165 | * xol_alloc_area - Allocate process's xol_area. | |
1166 | * This area will be used for storing instructions for execution out of | |
1167 | * line. | |
1168 | * | |
1169 | * Returns the allocated area or NULL. | |
1170 | */ | |
1171 | static struct xol_area *xol_alloc_area(void) | |
1172 | { | |
1173 | struct xol_area *area; | |
1174 | ||
1175 | area = kzalloc(sizeof(*area), GFP_KERNEL); | |
1176 | if (unlikely(!area)) | |
1177 | return NULL; | |
1178 | ||
1179 | area->bitmap = kzalloc(BITS_TO_LONGS(UINSNS_PER_PAGE) * sizeof(long), GFP_KERNEL); | |
1180 | ||
1181 | if (!area->bitmap) | |
1182 | goto fail; | |
1183 | ||
1184 | init_waitqueue_head(&area->wq); | |
1185 | if (!xol_add_vma(area)) | |
1186 | return area; | |
1187 | ||
1188 | fail: | |
1189 | kfree(area->bitmap); | |
1190 | kfree(area); | |
1191 | ||
1192 | return get_xol_area(current->mm); | |
1193 | } | |
1194 | ||
1195 | /* | |
1196 | * uprobe_clear_state - Free the area allocated for slots. | |
1197 | */ | |
1198 | void uprobe_clear_state(struct mm_struct *mm) | |
1199 | { | |
1200 | struct xol_area *area = mm->uprobes_state.xol_area; | |
1201 | ||
1202 | if (!area) | |
1203 | return; | |
1204 | ||
1205 | put_page(area->page); | |
1206 | kfree(area->bitmap); | |
1207 | kfree(area); | |
1208 | } | |
1209 | ||
1210 | /* | |
1211 | * uprobe_reset_state - Free the area allocated for slots. | |
1212 | */ | |
1213 | void uprobe_reset_state(struct mm_struct *mm) | |
1214 | { | |
1215 | mm->uprobes_state.xol_area = NULL; | |
682968e0 | 1216 | atomic_set(&mm->uprobes_state.count, 0); |
d4b3b638 SD |
1217 | } |
1218 | ||
1219 | /* | |
1220 | * - search for a free slot. | |
1221 | */ | |
1222 | static unsigned long xol_take_insn_slot(struct xol_area *area) | |
1223 | { | |
1224 | unsigned long slot_addr; | |
1225 | int slot_nr; | |
1226 | ||
1227 | do { | |
1228 | slot_nr = find_first_zero_bit(area->bitmap, UINSNS_PER_PAGE); | |
1229 | if (slot_nr < UINSNS_PER_PAGE) { | |
1230 | if (!test_and_set_bit(slot_nr, area->bitmap)) | |
1231 | break; | |
1232 | ||
1233 | slot_nr = UINSNS_PER_PAGE; | |
1234 | continue; | |
1235 | } | |
1236 | wait_event(area->wq, (atomic_read(&area->slot_count) < UINSNS_PER_PAGE)); | |
1237 | } while (slot_nr >= UINSNS_PER_PAGE); | |
1238 | ||
1239 | slot_addr = area->vaddr + (slot_nr * UPROBE_XOL_SLOT_BYTES); | |
1240 | atomic_inc(&area->slot_count); | |
1241 | ||
1242 | return slot_addr; | |
1243 | } | |
1244 | ||
1245 | /* | |
1246 | * xol_get_insn_slot - If was not allocated a slot, then | |
1247 | * allocate a slot. | |
1248 | * Returns the allocated slot address or 0. | |
1249 | */ | |
1250 | static unsigned long xol_get_insn_slot(struct uprobe *uprobe, unsigned long slot_addr) | |
1251 | { | |
1252 | struct xol_area *area; | |
1253 | unsigned long offset; | |
1254 | void *vaddr; | |
1255 | ||
1256 | area = get_xol_area(current->mm); | |
1257 | if (!area) { | |
1258 | area = xol_alloc_area(); | |
1259 | if (!area) | |
1260 | return 0; | |
1261 | } | |
1262 | current->utask->xol_vaddr = xol_take_insn_slot(area); | |
1263 | ||
1264 | /* | |
1265 | * Initialize the slot if xol_vaddr points to valid | |
1266 | * instruction slot. | |
1267 | */ | |
1268 | if (unlikely(!current->utask->xol_vaddr)) | |
1269 | return 0; | |
1270 | ||
1271 | current->utask->vaddr = slot_addr; | |
1272 | offset = current->utask->xol_vaddr & ~PAGE_MASK; | |
1273 | vaddr = kmap_atomic(area->page); | |
1274 | memcpy(vaddr + offset, uprobe->arch.insn, MAX_UINSN_BYTES); | |
1275 | kunmap_atomic(vaddr); | |
1276 | ||
1277 | return current->utask->xol_vaddr; | |
1278 | } | |
1279 | ||
1280 | /* | |
1281 | * xol_free_insn_slot - If slot was earlier allocated by | |
1282 | * @xol_get_insn_slot(), make the slot available for | |
1283 | * subsequent requests. | |
1284 | */ | |
1285 | static void xol_free_insn_slot(struct task_struct *tsk) | |
1286 | { | |
1287 | struct xol_area *area; | |
1288 | unsigned long vma_end; | |
1289 | unsigned long slot_addr; | |
1290 | ||
1291 | if (!tsk->mm || !tsk->mm->uprobes_state.xol_area || !tsk->utask) | |
1292 | return; | |
1293 | ||
1294 | slot_addr = tsk->utask->xol_vaddr; | |
1295 | ||
1296 | if (unlikely(!slot_addr || IS_ERR_VALUE(slot_addr))) | |
1297 | return; | |
1298 | ||
1299 | area = tsk->mm->uprobes_state.xol_area; | |
1300 | vma_end = area->vaddr + PAGE_SIZE; | |
1301 | if (area->vaddr <= slot_addr && slot_addr < vma_end) { | |
1302 | unsigned long offset; | |
1303 | int slot_nr; | |
1304 | ||
1305 | offset = slot_addr - area->vaddr; | |
1306 | slot_nr = offset / UPROBE_XOL_SLOT_BYTES; | |
1307 | if (slot_nr >= UINSNS_PER_PAGE) | |
1308 | return; | |
1309 | ||
1310 | clear_bit(slot_nr, area->bitmap); | |
1311 | atomic_dec(&area->slot_count); | |
1312 | if (waitqueue_active(&area->wq)) | |
1313 | wake_up(&area->wq); | |
1314 | ||
1315 | tsk->utask->xol_vaddr = 0; | |
1316 | } | |
1317 | } | |
1318 | ||
0326f5a9 SD |
1319 | /** |
1320 | * uprobe_get_swbp_addr - compute address of swbp given post-swbp regs | |
1321 | * @regs: Reflects the saved state of the task after it has hit a breakpoint | |
1322 | * instruction. | |
1323 | * Return the address of the breakpoint instruction. | |
1324 | */ | |
1325 | unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs) | |
1326 | { | |
1327 | return instruction_pointer(regs) - UPROBE_SWBP_INSN_SIZE; | |
1328 | } | |
1329 | ||
1330 | /* | |
1331 | * Called with no locks held. | |
1332 | * Called in context of a exiting or a exec-ing thread. | |
1333 | */ | |
1334 | void uprobe_free_utask(struct task_struct *t) | |
1335 | { | |
1336 | struct uprobe_task *utask = t->utask; | |
1337 | ||
0326f5a9 SD |
1338 | if (!utask) |
1339 | return; | |
1340 | ||
1341 | if (utask->active_uprobe) | |
1342 | put_uprobe(utask->active_uprobe); | |
1343 | ||
d4b3b638 | 1344 | xol_free_insn_slot(t); |
0326f5a9 SD |
1345 | kfree(utask); |
1346 | t->utask = NULL; | |
1347 | } | |
1348 | ||
1349 | /* | |
1350 | * Called in context of a new clone/fork from copy_process. | |
1351 | */ | |
1352 | void uprobe_copy_process(struct task_struct *t) | |
1353 | { | |
1354 | t->utask = NULL; | |
0326f5a9 SD |
1355 | } |
1356 | ||
1357 | /* | |
1358 | * Allocate a uprobe_task object for the task. | |
1359 | * Called when the thread hits a breakpoint for the first time. | |
1360 | * | |
1361 | * Returns: | |
1362 | * - pointer to new uprobe_task on success | |
1363 | * - NULL otherwise | |
1364 | */ | |
1365 | static struct uprobe_task *add_utask(void) | |
1366 | { | |
1367 | struct uprobe_task *utask; | |
1368 | ||
1369 | utask = kzalloc(sizeof *utask, GFP_KERNEL); | |
1370 | if (unlikely(!utask)) | |
1371 | return NULL; | |
1372 | ||
0326f5a9 SD |
1373 | current->utask = utask; |
1374 | return utask; | |
1375 | } | |
1376 | ||
1377 | /* Prepare to single-step probed instruction out of line. */ | |
1378 | static int | |
1379 | pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long vaddr) | |
1380 | { | |
d4b3b638 SD |
1381 | if (xol_get_insn_slot(uprobe, vaddr) && !arch_uprobe_pre_xol(&uprobe->arch, regs)) |
1382 | return 0; | |
1383 | ||
0326f5a9 SD |
1384 | return -EFAULT; |
1385 | } | |
1386 | ||
1387 | /* | |
1388 | * If we are singlestepping, then ensure this thread is not connected to | |
1389 | * non-fatal signals until completion of singlestep. When xol insn itself | |
1390 | * triggers the signal, restart the original insn even if the task is | |
1391 | * already SIGKILL'ed (since coredump should report the correct ip). This | |
1392 | * is even more important if the task has a handler for SIGSEGV/etc, The | |
1393 | * _same_ instruction should be repeated again after return from the signal | |
1394 | * handler, and SSTEP can never finish in this case. | |
1395 | */ | |
1396 | bool uprobe_deny_signal(void) | |
1397 | { | |
1398 | struct task_struct *t = current; | |
1399 | struct uprobe_task *utask = t->utask; | |
1400 | ||
1401 | if (likely(!utask || !utask->active_uprobe)) | |
1402 | return false; | |
1403 | ||
1404 | WARN_ON_ONCE(utask->state != UTASK_SSTEP); | |
1405 | ||
1406 | if (signal_pending(t)) { | |
1407 | spin_lock_irq(&t->sighand->siglock); | |
1408 | clear_tsk_thread_flag(t, TIF_SIGPENDING); | |
1409 | spin_unlock_irq(&t->sighand->siglock); | |
1410 | ||
1411 | if (__fatal_signal_pending(t) || arch_uprobe_xol_was_trapped(t)) { | |
1412 | utask->state = UTASK_SSTEP_TRAPPED; | |
1413 | set_tsk_thread_flag(t, TIF_UPROBE); | |
1414 | set_tsk_thread_flag(t, TIF_NOTIFY_RESUME); | |
1415 | } | |
1416 | } | |
1417 | ||
1418 | return true; | |
1419 | } | |
1420 | ||
1421 | /* | |
1422 | * Avoid singlestepping the original instruction if the original instruction | |
1423 | * is a NOP or can be emulated. | |
1424 | */ | |
1425 | static bool can_skip_sstep(struct uprobe *uprobe, struct pt_regs *regs) | |
1426 | { | |
1427 | if (arch_uprobe_skip_sstep(&uprobe->arch, regs)) | |
1428 | return true; | |
1429 | ||
1430 | uprobe->flags &= ~UPROBE_SKIP_SSTEP; | |
1431 | return false; | |
1432 | } | |
1433 | ||
d790d346 | 1434 | static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp) |
0326f5a9 | 1435 | { |
3a9ea052 ON |
1436 | struct mm_struct *mm = current->mm; |
1437 | struct uprobe *uprobe = NULL; | |
0326f5a9 | 1438 | struct vm_area_struct *vma; |
0326f5a9 | 1439 | |
0326f5a9 SD |
1440 | down_read(&mm->mmap_sem); |
1441 | vma = find_vma(mm, bp_vaddr); | |
3a9ea052 ON |
1442 | if (vma && vma->vm_start <= bp_vaddr) { |
1443 | if (valid_vma(vma, false)) { | |
1444 | struct inode *inode; | |
1445 | loff_t offset; | |
0326f5a9 | 1446 | |
3a9ea052 ON |
1447 | inode = vma->vm_file->f_mapping->host; |
1448 | offset = bp_vaddr - vma->vm_start; | |
1449 | offset += (vma->vm_pgoff << PAGE_SHIFT); | |
1450 | uprobe = find_uprobe(inode, offset); | |
1451 | } | |
d790d346 ON |
1452 | |
1453 | if (!uprobe) | |
1454 | *is_swbp = is_swbp_at_addr(mm, bp_vaddr); | |
1455 | } else { | |
1456 | *is_swbp = -EFAULT; | |
0326f5a9 | 1457 | } |
0326f5a9 SD |
1458 | up_read(&mm->mmap_sem); |
1459 | ||
3a9ea052 ON |
1460 | return uprobe; |
1461 | } | |
1462 | ||
1463 | /* | |
1464 | * Run handler and ask thread to singlestep. | |
1465 | * Ensure all non-fatal signals cannot interrupt thread while it singlesteps. | |
1466 | */ | |
1467 | static void handle_swbp(struct pt_regs *regs) | |
1468 | { | |
1469 | struct uprobe_task *utask; | |
1470 | struct uprobe *uprobe; | |
1471 | unsigned long bp_vaddr; | |
56bb4cf6 | 1472 | int uninitialized_var(is_swbp); |
3a9ea052 ON |
1473 | |
1474 | bp_vaddr = uprobe_get_swbp_addr(regs); | |
d790d346 | 1475 | uprobe = find_active_uprobe(bp_vaddr, &is_swbp); |
3a9ea052 | 1476 | |
0326f5a9 | 1477 | if (!uprobe) { |
56bb4cf6 ON |
1478 | if (is_swbp > 0) { |
1479 | /* No matching uprobe; signal SIGTRAP. */ | |
1480 | send_sig(SIGTRAP, current, 0); | |
1481 | } else { | |
1482 | /* | |
1483 | * Either we raced with uprobe_unregister() or we can't | |
1484 | * access this memory. The latter is only possible if | |
1485 | * another thread plays with our ->mm. In both cases | |
1486 | * we can simply restart. If this vma was unmapped we | |
1487 | * can pretend this insn was not executed yet and get | |
1488 | * the (correct) SIGSEGV after restart. | |
1489 | */ | |
1490 | instruction_pointer_set(regs, bp_vaddr); | |
1491 | } | |
0326f5a9 SD |
1492 | return; |
1493 | } | |
1494 | ||
1495 | utask = current->utask; | |
1496 | if (!utask) { | |
1497 | utask = add_utask(); | |
1498 | /* Cannot allocate; re-execute the instruction. */ | |
1499 | if (!utask) | |
1500 | goto cleanup_ret; | |
1501 | } | |
1502 | utask->active_uprobe = uprobe; | |
1503 | handler_chain(uprobe, regs); | |
1504 | if (uprobe->flags & UPROBE_SKIP_SSTEP && can_skip_sstep(uprobe, regs)) | |
1505 | goto cleanup_ret; | |
1506 | ||
1507 | utask->state = UTASK_SSTEP; | |
1508 | if (!pre_ssout(uprobe, regs, bp_vaddr)) { | |
1509 | user_enable_single_step(current); | |
1510 | return; | |
1511 | } | |
1512 | ||
1513 | cleanup_ret: | |
1514 | if (utask) { | |
1515 | utask->active_uprobe = NULL; | |
1516 | utask->state = UTASK_RUNNING; | |
1517 | } | |
1518 | if (uprobe) { | |
1519 | if (!(uprobe->flags & UPROBE_SKIP_SSTEP)) | |
1520 | ||
1521 | /* | |
1522 | * cannot singlestep; cannot skip instruction; | |
1523 | * re-execute the instruction. | |
1524 | */ | |
1525 | instruction_pointer_set(regs, bp_vaddr); | |
1526 | ||
1527 | put_uprobe(uprobe); | |
1528 | } | |
1529 | } | |
1530 | ||
1531 | /* | |
1532 | * Perform required fix-ups and disable singlestep. | |
1533 | * Allow pending signals to take effect. | |
1534 | */ | |
1535 | static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs) | |
1536 | { | |
1537 | struct uprobe *uprobe; | |
1538 | ||
1539 | uprobe = utask->active_uprobe; | |
1540 | if (utask->state == UTASK_SSTEP_ACK) | |
1541 | arch_uprobe_post_xol(&uprobe->arch, regs); | |
1542 | else if (utask->state == UTASK_SSTEP_TRAPPED) | |
1543 | arch_uprobe_abort_xol(&uprobe->arch, regs); | |
1544 | else | |
1545 | WARN_ON_ONCE(1); | |
1546 | ||
1547 | put_uprobe(uprobe); | |
1548 | utask->active_uprobe = NULL; | |
1549 | utask->state = UTASK_RUNNING; | |
1550 | user_disable_single_step(current); | |
d4b3b638 | 1551 | xol_free_insn_slot(current); |
0326f5a9 SD |
1552 | |
1553 | spin_lock_irq(¤t->sighand->siglock); | |
1554 | recalc_sigpending(); /* see uprobe_deny_signal() */ | |
1555 | spin_unlock_irq(¤t->sighand->siglock); | |
1556 | } | |
1557 | ||
1558 | /* | |
1559 | * On breakpoint hit, breakpoint notifier sets the TIF_UPROBE flag. (and on | |
1560 | * subsequent probe hits on the thread sets the state to UTASK_BP_HIT) and | |
1561 | * allows the thread to return from interrupt. | |
1562 | * | |
1563 | * On singlestep exception, singlestep notifier sets the TIF_UPROBE flag and | |
1564 | * also sets the state to UTASK_SSTEP_ACK and allows the thread to return from | |
1565 | * interrupt. | |
1566 | * | |
1567 | * While returning to userspace, thread notices the TIF_UPROBE flag and calls | |
1568 | * uprobe_notify_resume(). | |
1569 | */ | |
1570 | void uprobe_notify_resume(struct pt_regs *regs) | |
1571 | { | |
1572 | struct uprobe_task *utask; | |
1573 | ||
1574 | utask = current->utask; | |
1575 | if (!utask || utask->state == UTASK_BP_HIT) | |
1576 | handle_swbp(regs); | |
1577 | else | |
1578 | handle_singlestep(utask, regs); | |
1579 | } | |
1580 | ||
1581 | /* | |
1582 | * uprobe_pre_sstep_notifier gets called from interrupt context as part of | |
1583 | * notifier mechanism. Set TIF_UPROBE flag and indicate breakpoint hit. | |
1584 | */ | |
1585 | int uprobe_pre_sstep_notifier(struct pt_regs *regs) | |
1586 | { | |
1587 | struct uprobe_task *utask; | |
1588 | ||
682968e0 SD |
1589 | if (!current->mm || !atomic_read(¤t->mm->uprobes_state.count)) |
1590 | /* task is currently not uprobed */ | |
0326f5a9 SD |
1591 | return 0; |
1592 | ||
1593 | utask = current->utask; | |
1594 | if (utask) | |
1595 | utask->state = UTASK_BP_HIT; | |
1596 | ||
1597 | set_thread_flag(TIF_UPROBE); | |
0326f5a9 SD |
1598 | |
1599 | return 1; | |
1600 | } | |
1601 | ||
1602 | /* | |
1603 | * uprobe_post_sstep_notifier gets called in interrupt context as part of notifier | |
1604 | * mechanism. Set TIF_UPROBE flag and indicate completion of singlestep. | |
1605 | */ | |
1606 | int uprobe_post_sstep_notifier(struct pt_regs *regs) | |
1607 | { | |
1608 | struct uprobe_task *utask = current->utask; | |
1609 | ||
1610 | if (!current->mm || !utask || !utask->active_uprobe) | |
1611 | /* task is currently not uprobed */ | |
1612 | return 0; | |
1613 | ||
1614 | utask->state = UTASK_SSTEP_ACK; | |
1615 | set_thread_flag(TIF_UPROBE); | |
1616 | return 1; | |
1617 | } | |
1618 | ||
1619 | static struct notifier_block uprobe_exception_nb = { | |
1620 | .notifier_call = arch_uprobe_exception_notify, | |
1621 | .priority = INT_MAX-1, /* notified after kprobes, kgdb */ | |
1622 | }; | |
1623 | ||
2b144498 SD |
1624 | static int __init init_uprobes(void) |
1625 | { | |
1626 | int i; | |
1627 | ||
1628 | for (i = 0; i < UPROBES_HASH_SZ; i++) { | |
1629 | mutex_init(&uprobes_mutex[i]); | |
1630 | mutex_init(&uprobes_mmap_mutex[i]); | |
1631 | } | |
0326f5a9 SD |
1632 | |
1633 | return register_die_notifier(&uprobe_exception_nb); | |
2b144498 | 1634 | } |
0326f5a9 | 1635 | module_init(init_uprobes); |
2b144498 SD |
1636 | |
1637 | static void __exit exit_uprobes(void) | |
1638 | { | |
1639 | } | |
2b144498 | 1640 | module_exit(exit_uprobes); |