Commit | Line | Data |
---|---|---|
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 */ | |
194f8dcb | 35 | #include "../../mm/internal.h" /* munlock_vma_page */ |
32cdba1e | 36 | #include <linux/percpu-rwsem.h> |
7b2d81d4 | 37 | |
2b144498 SD |
38 | #include <linux/uprobes.h> |
39 | ||
d4b3b638 SD |
40 | #define UINSNS_PER_PAGE (PAGE_SIZE/UPROBE_XOL_SLOT_BYTES) |
41 | #define MAX_UPROBE_XOL_SLOTS UINSNS_PER_PAGE | |
42 | ||
2b144498 | 43 | static struct rb_root uprobes_tree = RB_ROOT; |
7b2d81d4 | 44 | |
2b144498 SD |
45 | static DEFINE_SPINLOCK(uprobes_treelock); /* serialize rbtree access */ |
46 | ||
47 | #define UPROBES_HASH_SZ 13 | |
7b2d81d4 | 48 | |
c5784de2 PZ |
49 | /* |
50 | * We need separate register/unregister and mmap/munmap lock hashes because | |
51 | * of mmap_sem nesting. | |
52 | * | |
53 | * uprobe_register() needs to install probes on (potentially) all processes | |
54 | * and thus needs to acquire multiple mmap_sems (consequtively, not | |
55 | * concurrently), whereas uprobe_mmap() is called while holding mmap_sem | |
56 | * for the particular process doing the mmap. | |
57 | * | |
58 | * uprobe_register()->register_for_each_vma() needs to drop/acquire mmap_sem | |
59 | * because of lock order against i_mmap_mutex. This means there's a hole in | |
60 | * the register vma iteration where a mmap() can happen. | |
61 | * | |
62 | * Thus uprobe_register() can race with uprobe_mmap() and we can try and | |
63 | * install a probe where one is already installed. | |
64 | */ | |
65 | ||
2b144498 SD |
66 | /* serialize (un)register */ |
67 | static struct mutex uprobes_mutex[UPROBES_HASH_SZ]; | |
7b2d81d4 IM |
68 | |
69 | #define uprobes_hash(v) (&uprobes_mutex[((unsigned long)(v)) % UPROBES_HASH_SZ]) | |
2b144498 SD |
70 | |
71 | /* serialize uprobe->pending_list */ | |
72 | static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ]; | |
7b2d81d4 | 73 | #define uprobes_mmap_hash(v) (&uprobes_mmap_mutex[((unsigned long)(v)) % UPROBES_HASH_SZ]) |
2b144498 | 74 | |
32cdba1e ON |
75 | static struct percpu_rw_semaphore dup_mmap_sem; |
76 | ||
2b144498 | 77 | /* |
7b2d81d4 | 78 | * uprobe_events allows us to skip the uprobe_mmap if there are no uprobe |
2b144498 SD |
79 | * events active at this time. Probably a fine grained per inode count is |
80 | * better? | |
81 | */ | |
82 | static atomic_t uprobe_events = ATOMIC_INIT(0); | |
83 | ||
cb9a19fe | 84 | /* Have a copy of original instruction */ |
71434f2f | 85 | #define UPROBE_COPY_INSN 0 |
cb9a19fe | 86 | /* Can skip singlestep */ |
bb929284 | 87 | #define UPROBE_SKIP_SSTEP 1 |
cb9a19fe | 88 | |
3ff54efd SD |
89 | struct uprobe { |
90 | struct rb_node rb_node; /* node in the rb tree */ | |
91 | atomic_t ref; | |
e591c8d7 | 92 | struct rw_semaphore register_rwsem; |
3ff54efd SD |
93 | struct rw_semaphore consumer_rwsem; |
94 | struct list_head pending_list; | |
95 | struct uprobe_consumer *consumers; | |
96 | struct inode *inode; /* Also hold a ref to inode */ | |
97 | loff_t offset; | |
71434f2f | 98 | unsigned long flags; |
3ff54efd SD |
99 | struct arch_uprobe arch; |
100 | }; | |
101 | ||
2b144498 SD |
102 | /* |
103 | * valid_vma: Verify if the specified vma is an executable vma | |
104 | * Relax restrictions while unregistering: vm_flags might have | |
105 | * changed after breakpoint was inserted. | |
106 | * - is_register: indicates if we are in register context. | |
107 | * - Return 1 if the specified virtual address is in an | |
108 | * executable vma. | |
109 | */ | |
110 | static bool valid_vma(struct vm_area_struct *vma, bool is_register) | |
111 | { | |
e40cfce6 | 112 | vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_SHARED; |
2b144498 | 113 | |
e40cfce6 ON |
114 | if (is_register) |
115 | flags |= VM_WRITE; | |
2b144498 | 116 | |
e40cfce6 | 117 | return vma->vm_file && (vma->vm_flags & flags) == VM_MAYEXEC; |
2b144498 SD |
118 | } |
119 | ||
57683f72 | 120 | static unsigned long offset_to_vaddr(struct vm_area_struct *vma, loff_t offset) |
2b144498 | 121 | { |
57683f72 | 122 | return vma->vm_start + offset - ((loff_t)vma->vm_pgoff << PAGE_SHIFT); |
2b144498 SD |
123 | } |
124 | ||
cb113b47 ON |
125 | static loff_t vaddr_to_offset(struct vm_area_struct *vma, unsigned long vaddr) |
126 | { | |
127 | return ((loff_t)vma->vm_pgoff << PAGE_SHIFT) + (vaddr - vma->vm_start); | |
128 | } | |
129 | ||
2b144498 SD |
130 | /** |
131 | * __replace_page - replace page in vma by new page. | |
132 | * based on replace_page in mm/ksm.c | |
133 | * | |
134 | * @vma: vma that holds the pte pointing to page | |
c517ee74 | 135 | * @addr: address the old @page is mapped at |
2b144498 SD |
136 | * @page: the cowed page we are replacing by kpage |
137 | * @kpage: the modified page we replace page by | |
138 | * | |
139 | * Returns 0 on success, -EFAULT on failure. | |
140 | */ | |
c517ee74 ON |
141 | static int __replace_page(struct vm_area_struct *vma, unsigned long addr, |
142 | struct page *page, struct page *kpage) | |
2b144498 SD |
143 | { |
144 | struct mm_struct *mm = vma->vm_mm; | |
5323ce71 ON |
145 | spinlock_t *ptl; |
146 | pte_t *ptep; | |
9f92448c | 147 | int err; |
6bdb913f HE |
148 | /* For mmu_notifiers */ |
149 | const unsigned long mmun_start = addr; | |
150 | const unsigned long mmun_end = addr + PAGE_SIZE; | |
2b144498 | 151 | |
194f8dcb | 152 | /* For try_to_free_swap() and munlock_vma_page() below */ |
9f92448c ON |
153 | lock_page(page); |
154 | ||
6bdb913f | 155 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); |
9f92448c | 156 | err = -EAGAIN; |
5323ce71 | 157 | ptep = page_check_address(page, mm, addr, &ptl, 0); |
2b144498 | 158 | if (!ptep) |
9f92448c | 159 | goto unlock; |
2b144498 SD |
160 | |
161 | get_page(kpage); | |
162 | page_add_new_anon_rmap(kpage, vma, addr); | |
163 | ||
7396fa81 SD |
164 | if (!PageAnon(page)) { |
165 | dec_mm_counter(mm, MM_FILEPAGES); | |
166 | inc_mm_counter(mm, MM_ANONPAGES); | |
167 | } | |
168 | ||
2b144498 SD |
169 | flush_cache_page(vma, addr, pte_pfn(*ptep)); |
170 | ptep_clear_flush(vma, addr, ptep); | |
171 | set_pte_at_notify(mm, addr, ptep, mk_pte(kpage, vma->vm_page_prot)); | |
172 | ||
173 | page_remove_rmap(page); | |
174 | if (!page_mapped(page)) | |
175 | try_to_free_swap(page); | |
2b144498 | 176 | pte_unmap_unlock(ptep, ptl); |
2b144498 | 177 | |
194f8dcb ON |
178 | if (vma->vm_flags & VM_LOCKED) |
179 | munlock_vma_page(page); | |
180 | put_page(page); | |
181 | ||
9f92448c ON |
182 | err = 0; |
183 | unlock: | |
6bdb913f | 184 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
9f92448c ON |
185 | unlock_page(page); |
186 | return err; | |
2b144498 SD |
187 | } |
188 | ||
189 | /** | |
5cb4ac3a | 190 | * is_swbp_insn - check if instruction is breakpoint instruction. |
2b144498 | 191 | * @insn: instruction to be checked. |
5cb4ac3a | 192 | * Default implementation of is_swbp_insn |
2b144498 SD |
193 | * Returns true if @insn is a breakpoint instruction. |
194 | */ | |
5cb4ac3a | 195 | bool __weak is_swbp_insn(uprobe_opcode_t *insn) |
2b144498 | 196 | { |
5cb4ac3a | 197 | return *insn == UPROBE_SWBP_INSN; |
2b144498 SD |
198 | } |
199 | ||
cceb55aa ON |
200 | static void copy_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *opcode) |
201 | { | |
202 | void *kaddr = kmap_atomic(page); | |
203 | memcpy(opcode, kaddr + (vaddr & ~PAGE_MASK), UPROBE_SWBP_INSN_SIZE); | |
204 | kunmap_atomic(kaddr); | |
205 | } | |
206 | ||
ed6f6a50 ON |
207 | static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *new_opcode) |
208 | { | |
209 | uprobe_opcode_t old_opcode; | |
210 | bool is_swbp; | |
211 | ||
212 | copy_opcode(page, vaddr, &old_opcode); | |
213 | is_swbp = is_swbp_insn(&old_opcode); | |
214 | ||
215 | if (is_swbp_insn(new_opcode)) { | |
216 | if (is_swbp) /* register: already installed? */ | |
217 | return 0; | |
218 | } else { | |
219 | if (!is_swbp) /* unregister: was it changed by us? */ | |
076a365b | 220 | return 0; |
ed6f6a50 ON |
221 | } |
222 | ||
223 | return 1; | |
224 | } | |
225 | ||
2b144498 SD |
226 | /* |
227 | * NOTE: | |
228 | * Expect the breakpoint instruction to be the smallest size instruction for | |
229 | * the architecture. If an arch has variable length instruction and the | |
230 | * breakpoint instruction is not of the smallest length instruction | |
cceb55aa | 231 | * supported by that architecture then we need to modify is_swbp_at_addr and |
2b144498 SD |
232 | * write_opcode accordingly. This would never be a problem for archs that |
233 | * have fixed length instructions. | |
234 | */ | |
235 | ||
236 | /* | |
237 | * write_opcode - write the opcode at a given virtual address. | |
238 | * @mm: the probed process address space. | |
2b144498 SD |
239 | * @vaddr: the virtual address to store the opcode. |
240 | * @opcode: opcode to be written at @vaddr. | |
241 | * | |
242 | * Called with mm->mmap_sem held (for read and with a reference to | |
243 | * mm). | |
244 | * | |
245 | * For mm @mm, write the opcode at @vaddr. | |
246 | * Return 0 (success) or a negative errno. | |
247 | */ | |
cceb55aa ON |
248 | static int write_opcode(struct mm_struct *mm, unsigned long vaddr, |
249 | uprobe_opcode_t opcode) | |
2b144498 SD |
250 | { |
251 | struct page *old_page, *new_page; | |
2b144498 SD |
252 | void *vaddr_old, *vaddr_new; |
253 | struct vm_area_struct *vma; | |
2b144498 | 254 | int ret; |
f403072c | 255 | |
5323ce71 | 256 | retry: |
2b144498 | 257 | /* Read the page with vaddr into memory */ |
75ed82ea | 258 | ret = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &old_page, &vma); |
2b144498 SD |
259 | if (ret <= 0) |
260 | return ret; | |
7b2d81d4 | 261 | |
ed6f6a50 ON |
262 | ret = verify_opcode(old_page, vaddr, &opcode); |
263 | if (ret <= 0) | |
264 | goto put_old; | |
265 | ||
2b144498 SD |
266 | ret = -ENOMEM; |
267 | new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr); | |
268 | if (!new_page) | |
9f92448c | 269 | goto put_old; |
2b144498 SD |
270 | |
271 | __SetPageUptodate(new_page); | |
272 | ||
2b144498 SD |
273 | /* copy the page now that we've got it stable */ |
274 | vaddr_old = kmap_atomic(old_page); | |
275 | vaddr_new = kmap_atomic(new_page); | |
276 | ||
277 | memcpy(vaddr_new, vaddr_old, PAGE_SIZE); | |
d9c4a30e | 278 | memcpy(vaddr_new + (vaddr & ~PAGE_MASK), &opcode, UPROBE_SWBP_INSN_SIZE); |
2b144498 SD |
279 | |
280 | kunmap_atomic(vaddr_new); | |
281 | kunmap_atomic(vaddr_old); | |
282 | ||
283 | ret = anon_vma_prepare(vma); | |
284 | if (ret) | |
9f92448c | 285 | goto put_new; |
2b144498 | 286 | |
c517ee74 | 287 | ret = __replace_page(vma, vaddr, old_page, new_page); |
2b144498 | 288 | |
9f92448c | 289 | put_new: |
2b144498 | 290 | page_cache_release(new_page); |
9f92448c | 291 | put_old: |
7b2d81d4 IM |
292 | put_page(old_page); |
293 | ||
5323ce71 ON |
294 | if (unlikely(ret == -EAGAIN)) |
295 | goto retry; | |
2b144498 SD |
296 | return ret; |
297 | } | |
298 | ||
2b144498 | 299 | /** |
5cb4ac3a | 300 | * set_swbp - store breakpoint at a given address. |
e3343e6a | 301 | * @auprobe: arch specific probepoint information. |
2b144498 | 302 | * @mm: the probed process address space. |
2b144498 SD |
303 | * @vaddr: the virtual address to insert the opcode. |
304 | * | |
305 | * For mm @mm, store the breakpoint instruction at @vaddr. | |
306 | * Return 0 (success) or a negative errno. | |
307 | */ | |
5cb4ac3a | 308 | int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) |
2b144498 | 309 | { |
cceb55aa | 310 | return write_opcode(mm, vaddr, UPROBE_SWBP_INSN); |
2b144498 SD |
311 | } |
312 | ||
313 | /** | |
314 | * set_orig_insn - Restore the original instruction. | |
315 | * @mm: the probed process address space. | |
e3343e6a | 316 | * @auprobe: arch specific probepoint information. |
2b144498 | 317 | * @vaddr: the virtual address to insert the opcode. |
2b144498 SD |
318 | * |
319 | * For mm @mm, restore the original opcode (opcode) at @vaddr. | |
320 | * Return 0 (success) or a negative errno. | |
321 | */ | |
7b2d81d4 | 322 | int __weak |
ded86e7c | 323 | set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) |
2b144498 | 324 | { |
cceb55aa | 325 | return write_opcode(mm, vaddr, *(uprobe_opcode_t *)auprobe->insn); |
2b144498 SD |
326 | } |
327 | ||
328 | static int match_uprobe(struct uprobe *l, struct uprobe *r) | |
329 | { | |
330 | if (l->inode < r->inode) | |
331 | return -1; | |
7b2d81d4 | 332 | |
2b144498 SD |
333 | if (l->inode > r->inode) |
334 | return 1; | |
2b144498 | 335 | |
7b2d81d4 IM |
336 | if (l->offset < r->offset) |
337 | return -1; | |
338 | ||
339 | if (l->offset > r->offset) | |
340 | return 1; | |
2b144498 SD |
341 | |
342 | return 0; | |
343 | } | |
344 | ||
345 | static struct uprobe *__find_uprobe(struct inode *inode, loff_t offset) | |
346 | { | |
347 | struct uprobe u = { .inode = inode, .offset = offset }; | |
348 | struct rb_node *n = uprobes_tree.rb_node; | |
349 | struct uprobe *uprobe; | |
350 | int match; | |
351 | ||
352 | while (n) { | |
353 | uprobe = rb_entry(n, struct uprobe, rb_node); | |
354 | match = match_uprobe(&u, uprobe); | |
355 | if (!match) { | |
356 | atomic_inc(&uprobe->ref); | |
357 | return uprobe; | |
358 | } | |
7b2d81d4 | 359 | |
2b144498 SD |
360 | if (match < 0) |
361 | n = n->rb_left; | |
362 | else | |
363 | n = n->rb_right; | |
364 | } | |
365 | return NULL; | |
366 | } | |
367 | ||
368 | /* | |
369 | * Find a uprobe corresponding to a given inode:offset | |
370 | * Acquires uprobes_treelock | |
371 | */ | |
372 | static struct uprobe *find_uprobe(struct inode *inode, loff_t offset) | |
373 | { | |
374 | struct uprobe *uprobe; | |
2b144498 | 375 | |
6f47caa0 | 376 | spin_lock(&uprobes_treelock); |
2b144498 | 377 | uprobe = __find_uprobe(inode, offset); |
6f47caa0 | 378 | spin_unlock(&uprobes_treelock); |
7b2d81d4 | 379 | |
2b144498 SD |
380 | return uprobe; |
381 | } | |
382 | ||
383 | static struct uprobe *__insert_uprobe(struct uprobe *uprobe) | |
384 | { | |
385 | struct rb_node **p = &uprobes_tree.rb_node; | |
386 | struct rb_node *parent = NULL; | |
387 | struct uprobe *u; | |
388 | int match; | |
389 | ||
390 | while (*p) { | |
391 | parent = *p; | |
392 | u = rb_entry(parent, struct uprobe, rb_node); | |
393 | match = match_uprobe(uprobe, u); | |
394 | if (!match) { | |
395 | atomic_inc(&u->ref); | |
396 | return u; | |
397 | } | |
398 | ||
399 | if (match < 0) | |
400 | p = &parent->rb_left; | |
401 | else | |
402 | p = &parent->rb_right; | |
403 | ||
404 | } | |
7b2d81d4 | 405 | |
2b144498 SD |
406 | u = NULL; |
407 | rb_link_node(&uprobe->rb_node, parent, p); | |
408 | rb_insert_color(&uprobe->rb_node, &uprobes_tree); | |
409 | /* get access + creation ref */ | |
410 | atomic_set(&uprobe->ref, 2); | |
7b2d81d4 | 411 | |
2b144498 SD |
412 | return u; |
413 | } | |
414 | ||
415 | /* | |
7b2d81d4 | 416 | * Acquire uprobes_treelock. |
2b144498 SD |
417 | * Matching uprobe already exists in rbtree; |
418 | * increment (access refcount) and return the matching uprobe. | |
419 | * | |
420 | * No matching uprobe; insert the uprobe in rb_tree; | |
421 | * get a double refcount (access + creation) and return NULL. | |
422 | */ | |
423 | static struct uprobe *insert_uprobe(struct uprobe *uprobe) | |
424 | { | |
2b144498 SD |
425 | struct uprobe *u; |
426 | ||
6f47caa0 | 427 | spin_lock(&uprobes_treelock); |
2b144498 | 428 | u = __insert_uprobe(uprobe); |
6f47caa0 | 429 | spin_unlock(&uprobes_treelock); |
7b2d81d4 | 430 | |
2b144498 SD |
431 | return u; |
432 | } | |
433 | ||
434 | static void put_uprobe(struct uprobe *uprobe) | |
435 | { | |
436 | if (atomic_dec_and_test(&uprobe->ref)) | |
437 | kfree(uprobe); | |
438 | } | |
439 | ||
440 | static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) | |
441 | { | |
442 | struct uprobe *uprobe, *cur_uprobe; | |
443 | ||
444 | uprobe = kzalloc(sizeof(struct uprobe), GFP_KERNEL); | |
445 | if (!uprobe) | |
446 | return NULL; | |
447 | ||
448 | uprobe->inode = igrab(inode); | |
449 | uprobe->offset = offset; | |
e591c8d7 | 450 | init_rwsem(&uprobe->register_rwsem); |
2b144498 | 451 | init_rwsem(&uprobe->consumer_rwsem); |
bbc33d05 ON |
452 | /* For now assume that the instruction need not be single-stepped */ |
453 | __set_bit(UPROBE_SKIP_SSTEP, &uprobe->flags); | |
2b144498 SD |
454 | |
455 | /* add to uprobes_tree, sorted on inode:offset */ | |
456 | cur_uprobe = insert_uprobe(uprobe); | |
457 | ||
458 | /* a uprobe exists for this inode:offset combination */ | |
459 | if (cur_uprobe) { | |
460 | kfree(uprobe); | |
461 | uprobe = cur_uprobe; | |
462 | iput(inode); | |
7b2d81d4 | 463 | } else { |
2b144498 | 464 | atomic_inc(&uprobe_events); |
7b2d81d4 IM |
465 | } |
466 | ||
2b144498 SD |
467 | return uprobe; |
468 | } | |
469 | ||
0326f5a9 SD |
470 | static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs) |
471 | { | |
472 | struct uprobe_consumer *uc; | |
473 | ||
e591c8d7 | 474 | down_read(&uprobe->register_rwsem); |
fe20d71f ON |
475 | for (uc = uprobe->consumers; uc; uc = uc->next) |
476 | uc->handler(uc, regs); | |
e591c8d7 | 477 | up_read(&uprobe->register_rwsem); |
0326f5a9 SD |
478 | } |
479 | ||
9a98e03c | 480 | static void consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc) |
2b144498 SD |
481 | { |
482 | down_write(&uprobe->consumer_rwsem); | |
e3343e6a SD |
483 | uc->next = uprobe->consumers; |
484 | uprobe->consumers = uc; | |
2b144498 | 485 | up_write(&uprobe->consumer_rwsem); |
2b144498 SD |
486 | } |
487 | ||
488 | /* | |
e3343e6a SD |
489 | * For uprobe @uprobe, delete the consumer @uc. |
490 | * Return true if the @uc is deleted successfully | |
2b144498 SD |
491 | * or return false. |
492 | */ | |
e3343e6a | 493 | static bool consumer_del(struct uprobe *uprobe, struct uprobe_consumer *uc) |
2b144498 SD |
494 | { |
495 | struct uprobe_consumer **con; | |
496 | bool ret = false; | |
497 | ||
498 | down_write(&uprobe->consumer_rwsem); | |
499 | for (con = &uprobe->consumers; *con; con = &(*con)->next) { | |
e3343e6a SD |
500 | if (*con == uc) { |
501 | *con = uc->next; | |
2b144498 SD |
502 | ret = true; |
503 | break; | |
504 | } | |
505 | } | |
506 | up_write(&uprobe->consumer_rwsem); | |
7b2d81d4 | 507 | |
2b144498 SD |
508 | return ret; |
509 | } | |
510 | ||
e3343e6a | 511 | static int |
d436615e | 512 | __copy_insn(struct address_space *mapping, struct file *filp, char *insn, |
593609a5 | 513 | unsigned long nbytes, loff_t offset) |
2b144498 | 514 | { |
2b144498 SD |
515 | struct page *page; |
516 | void *vaddr; | |
593609a5 ON |
517 | unsigned long off; |
518 | pgoff_t idx; | |
2b144498 SD |
519 | |
520 | if (!filp) | |
521 | return -EINVAL; | |
522 | ||
cc359d18 ON |
523 | if (!mapping->a_ops->readpage) |
524 | return -EIO; | |
525 | ||
593609a5 ON |
526 | idx = offset >> PAGE_CACHE_SHIFT; |
527 | off = offset & ~PAGE_MASK; | |
2b144498 SD |
528 | |
529 | /* | |
530 | * Ensure that the page that has the original instruction is | |
531 | * populated and in page-cache. | |
532 | */ | |
533 | page = read_mapping_page(mapping, idx, filp); | |
534 | if (IS_ERR(page)) | |
535 | return PTR_ERR(page); | |
536 | ||
537 | vaddr = kmap_atomic(page); | |
593609a5 | 538 | memcpy(insn, vaddr + off, nbytes); |
2b144498 SD |
539 | kunmap_atomic(vaddr); |
540 | page_cache_release(page); | |
7b2d81d4 | 541 | |
2b144498 SD |
542 | return 0; |
543 | } | |
544 | ||
d436615e | 545 | static int copy_insn(struct uprobe *uprobe, struct file *filp) |
2b144498 SD |
546 | { |
547 | struct address_space *mapping; | |
2b144498 | 548 | unsigned long nbytes; |
7b2d81d4 | 549 | int bytes; |
2b144498 | 550 | |
d436615e | 551 | nbytes = PAGE_SIZE - (uprobe->offset & ~PAGE_MASK); |
2b144498 SD |
552 | mapping = uprobe->inode->i_mapping; |
553 | ||
554 | /* Instruction at end of binary; copy only available bytes */ | |
555 | if (uprobe->offset + MAX_UINSN_BYTES > uprobe->inode->i_size) | |
556 | bytes = uprobe->inode->i_size - uprobe->offset; | |
557 | else | |
558 | bytes = MAX_UINSN_BYTES; | |
559 | ||
560 | /* Instruction at the page-boundary; copy bytes in second page */ | |
561 | if (nbytes < bytes) { | |
fc36f595 ON |
562 | int err = __copy_insn(mapping, filp, uprobe->arch.insn + nbytes, |
563 | bytes - nbytes, uprobe->offset + nbytes); | |
564 | if (err) | |
565 | return err; | |
2b144498 SD |
566 | bytes = nbytes; |
567 | } | |
d436615e | 568 | return __copy_insn(mapping, filp, uprobe->arch.insn, bytes, uprobe->offset); |
2b144498 SD |
569 | } |
570 | ||
cb9a19fe ON |
571 | static int prepare_uprobe(struct uprobe *uprobe, struct file *file, |
572 | struct mm_struct *mm, unsigned long vaddr) | |
573 | { | |
574 | int ret = 0; | |
575 | ||
71434f2f | 576 | if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) |
cb9a19fe ON |
577 | return ret; |
578 | ||
d4d3ccc6 ON |
579 | /* TODO: move this into _register, until then we abuse this sem. */ |
580 | down_write(&uprobe->consumer_rwsem); | |
71434f2f | 581 | if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) |
4710f05f ON |
582 | goto out; |
583 | ||
cb9a19fe ON |
584 | ret = copy_insn(uprobe, file); |
585 | if (ret) | |
586 | goto out; | |
587 | ||
588 | ret = -ENOTSUPP; | |
589 | if (is_swbp_insn((uprobe_opcode_t *)uprobe->arch.insn)) | |
590 | goto out; | |
591 | ||
592 | ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, vaddr); | |
593 | if (ret) | |
594 | goto out; | |
595 | ||
596 | /* write_opcode() assumes we don't cross page boundary */ | |
597 | BUG_ON((uprobe->offset & ~PAGE_MASK) + | |
598 | UPROBE_SWBP_INSN_SIZE > PAGE_SIZE); | |
599 | ||
600 | smp_wmb(); /* pairs with rmb() in find_active_uprobe() */ | |
71434f2f | 601 | set_bit(UPROBE_COPY_INSN, &uprobe->flags); |
cb9a19fe ON |
602 | |
603 | out: | |
d4d3ccc6 | 604 | up_write(&uprobe->consumer_rwsem); |
4710f05f | 605 | |
cb9a19fe ON |
606 | return ret; |
607 | } | |
608 | ||
63633cbf ON |
609 | static bool filter_chain(struct uprobe *uprobe) |
610 | { | |
1ff6fee5 ON |
611 | struct uprobe_consumer *uc; |
612 | bool ret = false; | |
613 | ||
614 | down_read(&uprobe->consumer_rwsem); | |
615 | for (uc = uprobe->consumers; uc; uc = uc->next) { | |
616 | /* TODO: ret = uc->filter(...) */ | |
617 | ret = true; | |
618 | if (ret) | |
619 | break; | |
620 | } | |
621 | up_read(&uprobe->consumer_rwsem); | |
622 | ||
623 | return ret; | |
63633cbf ON |
624 | } |
625 | ||
e3343e6a SD |
626 | static int |
627 | install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, | |
816c03fb | 628 | struct vm_area_struct *vma, unsigned long vaddr) |
2b144498 | 629 | { |
f8ac4ec9 | 630 | bool first_uprobe; |
2b144498 SD |
631 | int ret; |
632 | ||
633 | /* | |
634 | * If probe is being deleted, unregister thread could be done with | |
635 | * the vma-rmap-walk through. Adding a probe now can be fatal since | |
63633cbf ON |
636 | * nobody will be able to cleanup. But in this case filter_chain() |
637 | * must return false, all consumers have gone away. | |
2b144498 | 638 | */ |
63633cbf | 639 | if (!filter_chain(uprobe)) |
78f74116 | 640 | return 0; |
2b144498 | 641 | |
cb9a19fe ON |
642 | ret = prepare_uprobe(uprobe, vma->vm_file, mm, vaddr); |
643 | if (ret) | |
644 | return ret; | |
682968e0 | 645 | |
f8ac4ec9 ON |
646 | /* |
647 | * set MMF_HAS_UPROBES in advance for uprobe_pre_sstep_notifier(), | |
648 | * the task can hit this breakpoint right after __replace_page(). | |
649 | */ | |
650 | first_uprobe = !test_bit(MMF_HAS_UPROBES, &mm->flags); | |
651 | if (first_uprobe) | |
652 | set_bit(MMF_HAS_UPROBES, &mm->flags); | |
653 | ||
816c03fb | 654 | ret = set_swbp(&uprobe->arch, mm, vaddr); |
9f68f672 ON |
655 | if (!ret) |
656 | clear_bit(MMF_RECALC_UPROBES, &mm->flags); | |
657 | else if (first_uprobe) | |
f8ac4ec9 | 658 | clear_bit(MMF_HAS_UPROBES, &mm->flags); |
2b144498 SD |
659 | |
660 | return ret; | |
661 | } | |
662 | ||
076a365b | 663 | static int |
816c03fb | 664 | remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr) |
2b144498 | 665 | { |
9f68f672 | 666 | if (!test_bit(MMF_HAS_UPROBES, &mm->flags)) |
076a365b | 667 | return 0; |
9f68f672 | 668 | |
63633cbf ON |
669 | if (filter_chain(uprobe)) |
670 | return 0; | |
671 | ||
9f68f672 | 672 | set_bit(MMF_RECALC_UPROBES, &mm->flags); |
076a365b | 673 | return set_orig_insn(&uprobe->arch, mm, vaddr); |
2b144498 SD |
674 | } |
675 | ||
0326f5a9 | 676 | /* |
778b032d ON |
677 | * There could be threads that have already hit the breakpoint. They |
678 | * will recheck the current insn and restart if find_uprobe() fails. | |
679 | * See find_active_uprobe(). | |
0326f5a9 | 680 | */ |
2b144498 SD |
681 | static void delete_uprobe(struct uprobe *uprobe) |
682 | { | |
6f47caa0 | 683 | spin_lock(&uprobes_treelock); |
2b144498 | 684 | rb_erase(&uprobe->rb_node, &uprobes_tree); |
6f47caa0 | 685 | spin_unlock(&uprobes_treelock); |
2b144498 SD |
686 | iput(uprobe->inode); |
687 | put_uprobe(uprobe); | |
688 | atomic_dec(&uprobe_events); | |
689 | } | |
690 | ||
26872090 ON |
691 | struct map_info { |
692 | struct map_info *next; | |
693 | struct mm_struct *mm; | |
816c03fb | 694 | unsigned long vaddr; |
26872090 ON |
695 | }; |
696 | ||
697 | static inline struct map_info *free_map_info(struct map_info *info) | |
2b144498 | 698 | { |
26872090 ON |
699 | struct map_info *next = info->next; |
700 | kfree(info); | |
701 | return next; | |
702 | } | |
703 | ||
704 | static struct map_info * | |
705 | build_map_info(struct address_space *mapping, loff_t offset, bool is_register) | |
706 | { | |
707 | unsigned long pgoff = offset >> PAGE_SHIFT; | |
2b144498 | 708 | struct vm_area_struct *vma; |
26872090 ON |
709 | struct map_info *curr = NULL; |
710 | struct map_info *prev = NULL; | |
711 | struct map_info *info; | |
712 | int more = 0; | |
2b144498 | 713 | |
26872090 ON |
714 | again: |
715 | mutex_lock(&mapping->i_mmap_mutex); | |
6b2dbba8 | 716 | vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { |
2b144498 SD |
717 | if (!valid_vma(vma, is_register)) |
718 | continue; | |
719 | ||
7a5bfb66 ON |
720 | if (!prev && !more) { |
721 | /* | |
722 | * Needs GFP_NOWAIT to avoid i_mmap_mutex recursion through | |
723 | * reclaim. This is optimistic, no harm done if it fails. | |
724 | */ | |
725 | prev = kmalloc(sizeof(struct map_info), | |
726 | GFP_NOWAIT | __GFP_NOMEMALLOC | __GFP_NOWARN); | |
727 | if (prev) | |
728 | prev->next = NULL; | |
729 | } | |
26872090 ON |
730 | if (!prev) { |
731 | more++; | |
732 | continue; | |
2b144498 | 733 | } |
2b144498 | 734 | |
26872090 ON |
735 | if (!atomic_inc_not_zero(&vma->vm_mm->mm_users)) |
736 | continue; | |
7b2d81d4 | 737 | |
26872090 ON |
738 | info = prev; |
739 | prev = prev->next; | |
740 | info->next = curr; | |
741 | curr = info; | |
2b144498 | 742 | |
26872090 | 743 | info->mm = vma->vm_mm; |
57683f72 | 744 | info->vaddr = offset_to_vaddr(vma, offset); |
26872090 | 745 | } |
2b144498 SD |
746 | mutex_unlock(&mapping->i_mmap_mutex); |
747 | ||
26872090 ON |
748 | if (!more) |
749 | goto out; | |
750 | ||
751 | prev = curr; | |
752 | while (curr) { | |
753 | mmput(curr->mm); | |
754 | curr = curr->next; | |
755 | } | |
7b2d81d4 | 756 | |
26872090 ON |
757 | do { |
758 | info = kmalloc(sizeof(struct map_info), GFP_KERNEL); | |
759 | if (!info) { | |
760 | curr = ERR_PTR(-ENOMEM); | |
761 | goto out; | |
762 | } | |
763 | info->next = prev; | |
764 | prev = info; | |
765 | } while (--more); | |
766 | ||
767 | goto again; | |
768 | out: | |
769 | while (prev) | |
770 | prev = free_map_info(prev); | |
771 | return curr; | |
2b144498 SD |
772 | } |
773 | ||
774 | static int register_for_each_vma(struct uprobe *uprobe, bool is_register) | |
775 | { | |
26872090 ON |
776 | struct map_info *info; |
777 | int err = 0; | |
2b144498 | 778 | |
32cdba1e | 779 | percpu_down_write(&dup_mmap_sem); |
26872090 ON |
780 | info = build_map_info(uprobe->inode->i_mapping, |
781 | uprobe->offset, is_register); | |
32cdba1e ON |
782 | if (IS_ERR(info)) { |
783 | err = PTR_ERR(info); | |
784 | goto out; | |
785 | } | |
7b2d81d4 | 786 | |
26872090 ON |
787 | while (info) { |
788 | struct mm_struct *mm = info->mm; | |
789 | struct vm_area_struct *vma; | |
7b2d81d4 | 790 | |
076a365b | 791 | if (err && is_register) |
26872090 | 792 | goto free; |
7b2d81d4 | 793 | |
77fc4af1 | 794 | down_write(&mm->mmap_sem); |
f4d6dfe5 ON |
795 | vma = find_vma(mm, info->vaddr); |
796 | if (!vma || !valid_vma(vma, is_register) || | |
797 | vma->vm_file->f_mapping->host != uprobe->inode) | |
26872090 ON |
798 | goto unlock; |
799 | ||
f4d6dfe5 ON |
800 | if (vma->vm_start > info->vaddr || |
801 | vaddr_to_offset(vma, info->vaddr) != uprobe->offset) | |
26872090 | 802 | goto unlock; |
2b144498 | 803 | |
78f74116 | 804 | if (is_register) |
26872090 | 805 | err = install_breakpoint(uprobe, mm, vma, info->vaddr); |
78f74116 | 806 | else |
076a365b | 807 | err |= remove_breakpoint(uprobe, mm, info->vaddr); |
78f74116 | 808 | |
26872090 ON |
809 | unlock: |
810 | up_write(&mm->mmap_sem); | |
811 | free: | |
812 | mmput(mm); | |
813 | info = free_map_info(info); | |
2b144498 | 814 | } |
32cdba1e ON |
815 | out: |
816 | percpu_up_write(&dup_mmap_sem); | |
26872090 | 817 | return err; |
2b144498 SD |
818 | } |
819 | ||
9a98e03c | 820 | static int __uprobe_register(struct uprobe *uprobe, struct uprobe_consumer *uc) |
2b144498 | 821 | { |
9a98e03c | 822 | consumer_add(uprobe, uc); |
bb929284 | 823 | return register_for_each_vma(uprobe, true); |
2b144498 SD |
824 | } |
825 | ||
04aab9b2 | 826 | static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc) |
2b144498 | 827 | { |
04aab9b2 ON |
828 | int err; |
829 | ||
830 | if (!consumer_del(uprobe, uc)) /* WARN? */ | |
831 | return; | |
2b144498 | 832 | |
04aab9b2 | 833 | err = register_for_each_vma(uprobe, false); |
bb929284 ON |
834 | /* TODO : cant unregister? schedule a worker thread */ |
835 | if (!uprobe->consumers && !err) | |
836 | delete_uprobe(uprobe); | |
2b144498 SD |
837 | } |
838 | ||
839 | /* | |
7b2d81d4 | 840 | * uprobe_register - register a probe |
2b144498 SD |
841 | * @inode: the file in which the probe has to be placed. |
842 | * @offset: offset from the start of the file. | |
e3343e6a | 843 | * @uc: information on howto handle the probe.. |
2b144498 | 844 | * |
7b2d81d4 | 845 | * Apart from the access refcount, uprobe_register() takes a creation |
2b144498 SD |
846 | * refcount (thro alloc_uprobe) if and only if this @uprobe is getting |
847 | * inserted into the rbtree (i.e first consumer for a @inode:@offset | |
7b2d81d4 | 848 | * tuple). Creation refcount stops uprobe_unregister from freeing the |
2b144498 | 849 | * @uprobe even before the register operation is complete. Creation |
e3343e6a | 850 | * refcount is released when the last @uc for the @uprobe |
2b144498 SD |
851 | * unregisters. |
852 | * | |
853 | * Return errno if it cannot successully install probes | |
854 | * else return 0 (success) | |
855 | */ | |
e3343e6a | 856 | int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) |
2b144498 SD |
857 | { |
858 | struct uprobe *uprobe; | |
7b2d81d4 | 859 | int ret; |
2b144498 | 860 | |
f0744af7 | 861 | /* Racy, just to catch the obvious mistakes */ |
2b144498 | 862 | if (offset > i_size_read(inode)) |
7b2d81d4 | 863 | return -EINVAL; |
2b144498 | 864 | |
9a98e03c | 865 | ret = -ENOMEM; |
2b144498 SD |
866 | mutex_lock(uprobes_hash(inode)); |
867 | uprobe = alloc_uprobe(inode, offset); | |
9a98e03c | 868 | if (uprobe) { |
e591c8d7 | 869 | down_write(&uprobe->register_rwsem); |
9a98e03c ON |
870 | ret = __uprobe_register(uprobe, uc); |
871 | if (ret) | |
04aab9b2 | 872 | __uprobe_unregister(uprobe, uc); |
e591c8d7 | 873 | up_write(&uprobe->register_rwsem); |
2b144498 | 874 | } |
2b144498 | 875 | mutex_unlock(uprobes_hash(inode)); |
6d1d8dfa SAS |
876 | if (uprobe) |
877 | put_uprobe(uprobe); | |
2b144498 SD |
878 | |
879 | return ret; | |
880 | } | |
881 | ||
882 | /* | |
7b2d81d4 | 883 | * uprobe_unregister - unregister a already registered probe. |
2b144498 SD |
884 | * @inode: the file in which the probe has to be removed. |
885 | * @offset: offset from the start of the file. | |
e3343e6a | 886 | * @uc: identify which probe if multiple probes are colocated. |
2b144498 | 887 | */ |
e3343e6a | 888 | void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) |
2b144498 | 889 | { |
7b2d81d4 | 890 | struct uprobe *uprobe; |
2b144498 | 891 | |
2b144498 SD |
892 | uprobe = find_uprobe(inode, offset); |
893 | if (!uprobe) | |
894 | return; | |
895 | ||
896 | mutex_lock(uprobes_hash(inode)); | |
e591c8d7 | 897 | down_write(&uprobe->register_rwsem); |
04aab9b2 | 898 | __uprobe_unregister(uprobe, uc); |
e591c8d7 | 899 | up_write(&uprobe->register_rwsem); |
2b144498 | 900 | mutex_unlock(uprobes_hash(inode)); |
c91368c4 | 901 | put_uprobe(uprobe); |
2b144498 SD |
902 | } |
903 | ||
891c3970 ON |
904 | static struct rb_node * |
905 | find_node_in_range(struct inode *inode, loff_t min, loff_t max) | |
2b144498 | 906 | { |
2b144498 | 907 | struct rb_node *n = uprobes_tree.rb_node; |
2b144498 SD |
908 | |
909 | while (n) { | |
891c3970 | 910 | struct uprobe *u = rb_entry(n, struct uprobe, rb_node); |
2b144498 | 911 | |
891c3970 | 912 | if (inode < u->inode) { |
2b144498 | 913 | n = n->rb_left; |
891c3970 | 914 | } else if (inode > u->inode) { |
2b144498 | 915 | n = n->rb_right; |
891c3970 ON |
916 | } else { |
917 | if (max < u->offset) | |
918 | n = n->rb_left; | |
919 | else if (min > u->offset) | |
920 | n = n->rb_right; | |
921 | else | |
922 | break; | |
923 | } | |
2b144498 | 924 | } |
7b2d81d4 | 925 | |
891c3970 | 926 | return n; |
2b144498 SD |
927 | } |
928 | ||
929 | /* | |
891c3970 | 930 | * For a given range in vma, build a list of probes that need to be inserted. |
2b144498 | 931 | */ |
891c3970 ON |
932 | static void build_probe_list(struct inode *inode, |
933 | struct vm_area_struct *vma, | |
934 | unsigned long start, unsigned long end, | |
935 | struct list_head *head) | |
2b144498 | 936 | { |
891c3970 | 937 | loff_t min, max; |
891c3970 ON |
938 | struct rb_node *n, *t; |
939 | struct uprobe *u; | |
7b2d81d4 | 940 | |
891c3970 | 941 | INIT_LIST_HEAD(head); |
cb113b47 | 942 | min = vaddr_to_offset(vma, start); |
891c3970 | 943 | max = min + (end - start) - 1; |
2b144498 | 944 | |
6f47caa0 | 945 | spin_lock(&uprobes_treelock); |
891c3970 ON |
946 | n = find_node_in_range(inode, min, max); |
947 | if (n) { | |
948 | for (t = n; t; t = rb_prev(t)) { | |
949 | u = rb_entry(t, struct uprobe, rb_node); | |
950 | if (u->inode != inode || u->offset < min) | |
951 | break; | |
952 | list_add(&u->pending_list, head); | |
953 | atomic_inc(&u->ref); | |
954 | } | |
955 | for (t = n; (t = rb_next(t)); ) { | |
956 | u = rb_entry(t, struct uprobe, rb_node); | |
957 | if (u->inode != inode || u->offset > max) | |
958 | break; | |
959 | list_add(&u->pending_list, head); | |
960 | atomic_inc(&u->ref); | |
961 | } | |
2b144498 | 962 | } |
6f47caa0 | 963 | spin_unlock(&uprobes_treelock); |
2b144498 SD |
964 | } |
965 | ||
966 | /* | |
5e5be71a | 967 | * Called from mmap_region/vma_adjust with mm->mmap_sem acquired. |
2b144498 | 968 | * |
5e5be71a ON |
969 | * Currently we ignore all errors and always return 0, the callers |
970 | * can't handle the failure anyway. | |
2b144498 | 971 | */ |
7b2d81d4 | 972 | int uprobe_mmap(struct vm_area_struct *vma) |
2b144498 SD |
973 | { |
974 | struct list_head tmp_list; | |
665605a2 | 975 | struct uprobe *uprobe, *u; |
2b144498 | 976 | struct inode *inode; |
2b144498 SD |
977 | |
978 | if (!atomic_read(&uprobe_events) || !valid_vma(vma, true)) | |
7b2d81d4 | 979 | return 0; |
2b144498 SD |
980 | |
981 | inode = vma->vm_file->f_mapping->host; | |
982 | if (!inode) | |
7b2d81d4 | 983 | return 0; |
2b144498 | 984 | |
2b144498 | 985 | mutex_lock(uprobes_mmap_hash(inode)); |
891c3970 | 986 | build_probe_list(inode, vma, vma->vm_start, vma->vm_end, &tmp_list); |
7b2d81d4 | 987 | |
665605a2 | 988 | list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) { |
5e5be71a | 989 | if (!fatal_signal_pending(current)) { |
57683f72 | 990 | unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset); |
5e5be71a | 991 | install_breakpoint(uprobe, vma->vm_mm, vma, vaddr); |
2b144498 SD |
992 | } |
993 | put_uprobe(uprobe); | |
994 | } | |
2b144498 SD |
995 | mutex_unlock(uprobes_mmap_hash(inode)); |
996 | ||
5e5be71a | 997 | return 0; |
2b144498 SD |
998 | } |
999 | ||
9f68f672 ON |
1000 | static bool |
1001 | vma_has_uprobes(struct vm_area_struct *vma, unsigned long start, unsigned long end) | |
1002 | { | |
1003 | loff_t min, max; | |
1004 | struct inode *inode; | |
1005 | struct rb_node *n; | |
1006 | ||
1007 | inode = vma->vm_file->f_mapping->host; | |
1008 | ||
1009 | min = vaddr_to_offset(vma, start); | |
1010 | max = min + (end - start) - 1; | |
1011 | ||
1012 | spin_lock(&uprobes_treelock); | |
1013 | n = find_node_in_range(inode, min, max); | |
1014 | spin_unlock(&uprobes_treelock); | |
1015 | ||
1016 | return !!n; | |
1017 | } | |
1018 | ||
682968e0 SD |
1019 | /* |
1020 | * Called in context of a munmap of a vma. | |
1021 | */ | |
cbc91f71 | 1022 | void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end) |
682968e0 | 1023 | { |
682968e0 SD |
1024 | if (!atomic_read(&uprobe_events) || !valid_vma(vma, false)) |
1025 | return; | |
1026 | ||
2fd611a9 ON |
1027 | if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */ |
1028 | return; | |
1029 | ||
9f68f672 ON |
1030 | if (!test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags) || |
1031 | test_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags)) | |
f8ac4ec9 ON |
1032 | return; |
1033 | ||
9f68f672 ON |
1034 | if (vma_has_uprobes(vma, start, end)) |
1035 | set_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags); | |
682968e0 SD |
1036 | } |
1037 | ||
d4b3b638 SD |
1038 | /* Slot allocation for XOL */ |
1039 | static int xol_add_vma(struct xol_area *area) | |
1040 | { | |
1041 | struct mm_struct *mm; | |
1042 | int ret; | |
1043 | ||
1044 | area->page = alloc_page(GFP_HIGHUSER); | |
1045 | if (!area->page) | |
1046 | return -ENOMEM; | |
1047 | ||
1048 | ret = -EALREADY; | |
1049 | mm = current->mm; | |
1050 | ||
1051 | down_write(&mm->mmap_sem); | |
1052 | if (mm->uprobes_state.xol_area) | |
1053 | goto fail; | |
1054 | ||
1055 | ret = -ENOMEM; | |
1056 | ||
1057 | /* Try to map as high as possible, this is only a hint. */ | |
1058 | area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE, PAGE_SIZE, 0, 0); | |
1059 | if (area->vaddr & ~PAGE_MASK) { | |
1060 | ret = area->vaddr; | |
1061 | goto fail; | |
1062 | } | |
1063 | ||
1064 | ret = install_special_mapping(mm, area->vaddr, PAGE_SIZE, | |
1065 | VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO, &area->page); | |
1066 | if (ret) | |
1067 | goto fail; | |
1068 | ||
1069 | smp_wmb(); /* pairs with get_xol_area() */ | |
1070 | mm->uprobes_state.xol_area = area; | |
1071 | ret = 0; | |
1072 | ||
1073 | fail: | |
1074 | up_write(&mm->mmap_sem); | |
1075 | if (ret) | |
1076 | __free_page(area->page); | |
1077 | ||
1078 | return ret; | |
1079 | } | |
1080 | ||
1081 | static struct xol_area *get_xol_area(struct mm_struct *mm) | |
1082 | { | |
1083 | struct xol_area *area; | |
1084 | ||
1085 | area = mm->uprobes_state.xol_area; | |
1086 | smp_read_barrier_depends(); /* pairs with wmb in xol_add_vma() */ | |
1087 | ||
1088 | return area; | |
1089 | } | |
1090 | ||
1091 | /* | |
1092 | * xol_alloc_area - Allocate process's xol_area. | |
1093 | * This area will be used for storing instructions for execution out of | |
1094 | * line. | |
1095 | * | |
1096 | * Returns the allocated area or NULL. | |
1097 | */ | |
1098 | static struct xol_area *xol_alloc_area(void) | |
1099 | { | |
1100 | struct xol_area *area; | |
1101 | ||
1102 | area = kzalloc(sizeof(*area), GFP_KERNEL); | |
1103 | if (unlikely(!area)) | |
1104 | return NULL; | |
1105 | ||
1106 | area->bitmap = kzalloc(BITS_TO_LONGS(UINSNS_PER_PAGE) * sizeof(long), GFP_KERNEL); | |
1107 | ||
1108 | if (!area->bitmap) | |
1109 | goto fail; | |
1110 | ||
1111 | init_waitqueue_head(&area->wq); | |
1112 | if (!xol_add_vma(area)) | |
1113 | return area; | |
1114 | ||
1115 | fail: | |
1116 | kfree(area->bitmap); | |
1117 | kfree(area); | |
1118 | ||
1119 | return get_xol_area(current->mm); | |
1120 | } | |
1121 | ||
1122 | /* | |
1123 | * uprobe_clear_state - Free the area allocated for slots. | |
1124 | */ | |
1125 | void uprobe_clear_state(struct mm_struct *mm) | |
1126 | { | |
1127 | struct xol_area *area = mm->uprobes_state.xol_area; | |
1128 | ||
1129 | if (!area) | |
1130 | return; | |
1131 | ||
1132 | put_page(area->page); | |
1133 | kfree(area->bitmap); | |
1134 | kfree(area); | |
1135 | } | |
1136 | ||
32cdba1e ON |
1137 | void uprobe_start_dup_mmap(void) |
1138 | { | |
1139 | percpu_down_read(&dup_mmap_sem); | |
1140 | } | |
1141 | ||
1142 | void uprobe_end_dup_mmap(void) | |
1143 | { | |
1144 | percpu_up_read(&dup_mmap_sem); | |
1145 | } | |
1146 | ||
f8ac4ec9 ON |
1147 | void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm) |
1148 | { | |
61559a81 ON |
1149 | newmm->uprobes_state.xol_area = NULL; |
1150 | ||
9f68f672 | 1151 | if (test_bit(MMF_HAS_UPROBES, &oldmm->flags)) { |
f8ac4ec9 | 1152 | set_bit(MMF_HAS_UPROBES, &newmm->flags); |
9f68f672 ON |
1153 | /* unconditionally, dup_mmap() skips VM_DONTCOPY vmas */ |
1154 | set_bit(MMF_RECALC_UPROBES, &newmm->flags); | |
1155 | } | |
f8ac4ec9 ON |
1156 | } |
1157 | ||
d4b3b638 SD |
1158 | /* |
1159 | * - search for a free slot. | |
1160 | */ | |
1161 | static unsigned long xol_take_insn_slot(struct xol_area *area) | |
1162 | { | |
1163 | unsigned long slot_addr; | |
1164 | int slot_nr; | |
1165 | ||
1166 | do { | |
1167 | slot_nr = find_first_zero_bit(area->bitmap, UINSNS_PER_PAGE); | |
1168 | if (slot_nr < UINSNS_PER_PAGE) { | |
1169 | if (!test_and_set_bit(slot_nr, area->bitmap)) | |
1170 | break; | |
1171 | ||
1172 | slot_nr = UINSNS_PER_PAGE; | |
1173 | continue; | |
1174 | } | |
1175 | wait_event(area->wq, (atomic_read(&area->slot_count) < UINSNS_PER_PAGE)); | |
1176 | } while (slot_nr >= UINSNS_PER_PAGE); | |
1177 | ||
1178 | slot_addr = area->vaddr + (slot_nr * UPROBE_XOL_SLOT_BYTES); | |
1179 | atomic_inc(&area->slot_count); | |
1180 | ||
1181 | return slot_addr; | |
1182 | } | |
1183 | ||
1184 | /* | |
1185 | * xol_get_insn_slot - If was not allocated a slot, then | |
1186 | * allocate a slot. | |
1187 | * Returns the allocated slot address or 0. | |
1188 | */ | |
1189 | static unsigned long xol_get_insn_slot(struct uprobe *uprobe, unsigned long slot_addr) | |
1190 | { | |
1191 | struct xol_area *area; | |
1192 | unsigned long offset; | |
1193 | void *vaddr; | |
1194 | ||
1195 | area = get_xol_area(current->mm); | |
1196 | if (!area) { | |
1197 | area = xol_alloc_area(); | |
1198 | if (!area) | |
1199 | return 0; | |
1200 | } | |
1201 | current->utask->xol_vaddr = xol_take_insn_slot(area); | |
1202 | ||
1203 | /* | |
1204 | * Initialize the slot if xol_vaddr points to valid | |
1205 | * instruction slot. | |
1206 | */ | |
1207 | if (unlikely(!current->utask->xol_vaddr)) | |
1208 | return 0; | |
1209 | ||
1210 | current->utask->vaddr = slot_addr; | |
1211 | offset = current->utask->xol_vaddr & ~PAGE_MASK; | |
1212 | vaddr = kmap_atomic(area->page); | |
1213 | memcpy(vaddr + offset, uprobe->arch.insn, MAX_UINSN_BYTES); | |
1214 | kunmap_atomic(vaddr); | |
65b6ecc0 RV |
1215 | /* |
1216 | * We probably need flush_icache_user_range() but it needs vma. | |
1217 | * This should work on supported architectures too. | |
1218 | */ | |
1219 | flush_dcache_page(area->page); | |
d4b3b638 SD |
1220 | |
1221 | return current->utask->xol_vaddr; | |
1222 | } | |
1223 | ||
1224 | /* | |
1225 | * xol_free_insn_slot - If slot was earlier allocated by | |
1226 | * @xol_get_insn_slot(), make the slot available for | |
1227 | * subsequent requests. | |
1228 | */ | |
1229 | static void xol_free_insn_slot(struct task_struct *tsk) | |
1230 | { | |
1231 | struct xol_area *area; | |
1232 | unsigned long vma_end; | |
1233 | unsigned long slot_addr; | |
1234 | ||
1235 | if (!tsk->mm || !tsk->mm->uprobes_state.xol_area || !tsk->utask) | |
1236 | return; | |
1237 | ||
1238 | slot_addr = tsk->utask->xol_vaddr; | |
1239 | ||
1240 | if (unlikely(!slot_addr || IS_ERR_VALUE(slot_addr))) | |
1241 | return; | |
1242 | ||
1243 | area = tsk->mm->uprobes_state.xol_area; | |
1244 | vma_end = area->vaddr + PAGE_SIZE; | |
1245 | if (area->vaddr <= slot_addr && slot_addr < vma_end) { | |
1246 | unsigned long offset; | |
1247 | int slot_nr; | |
1248 | ||
1249 | offset = slot_addr - area->vaddr; | |
1250 | slot_nr = offset / UPROBE_XOL_SLOT_BYTES; | |
1251 | if (slot_nr >= UINSNS_PER_PAGE) | |
1252 | return; | |
1253 | ||
1254 | clear_bit(slot_nr, area->bitmap); | |
1255 | atomic_dec(&area->slot_count); | |
1256 | if (waitqueue_active(&area->wq)) | |
1257 | wake_up(&area->wq); | |
1258 | ||
1259 | tsk->utask->xol_vaddr = 0; | |
1260 | } | |
1261 | } | |
1262 | ||
0326f5a9 SD |
1263 | /** |
1264 | * uprobe_get_swbp_addr - compute address of swbp given post-swbp regs | |
1265 | * @regs: Reflects the saved state of the task after it has hit a breakpoint | |
1266 | * instruction. | |
1267 | * Return the address of the breakpoint instruction. | |
1268 | */ | |
1269 | unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs) | |
1270 | { | |
1271 | return instruction_pointer(regs) - UPROBE_SWBP_INSN_SIZE; | |
1272 | } | |
1273 | ||
1274 | /* | |
1275 | * Called with no locks held. | |
1276 | * Called in context of a exiting or a exec-ing thread. | |
1277 | */ | |
1278 | void uprobe_free_utask(struct task_struct *t) | |
1279 | { | |
1280 | struct uprobe_task *utask = t->utask; | |
1281 | ||
0326f5a9 SD |
1282 | if (!utask) |
1283 | return; | |
1284 | ||
1285 | if (utask->active_uprobe) | |
1286 | put_uprobe(utask->active_uprobe); | |
1287 | ||
d4b3b638 | 1288 | xol_free_insn_slot(t); |
0326f5a9 SD |
1289 | kfree(utask); |
1290 | t->utask = NULL; | |
1291 | } | |
1292 | ||
1293 | /* | |
1294 | * Called in context of a new clone/fork from copy_process. | |
1295 | */ | |
1296 | void uprobe_copy_process(struct task_struct *t) | |
1297 | { | |
1298 | t->utask = NULL; | |
0326f5a9 SD |
1299 | } |
1300 | ||
1301 | /* | |
1302 | * Allocate a uprobe_task object for the task. | |
1303 | * Called when the thread hits a breakpoint for the first time. | |
1304 | * | |
1305 | * Returns: | |
1306 | * - pointer to new uprobe_task on success | |
1307 | * - NULL otherwise | |
1308 | */ | |
1309 | static struct uprobe_task *add_utask(void) | |
1310 | { | |
1311 | struct uprobe_task *utask; | |
1312 | ||
1313 | utask = kzalloc(sizeof *utask, GFP_KERNEL); | |
1314 | if (unlikely(!utask)) | |
1315 | return NULL; | |
1316 | ||
0326f5a9 SD |
1317 | current->utask = utask; |
1318 | return utask; | |
1319 | } | |
1320 | ||
1321 | /* Prepare to single-step probed instruction out of line. */ | |
1322 | static int | |
1323 | pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long vaddr) | |
1324 | { | |
d4b3b638 SD |
1325 | if (xol_get_insn_slot(uprobe, vaddr) && !arch_uprobe_pre_xol(&uprobe->arch, regs)) |
1326 | return 0; | |
1327 | ||
0326f5a9 SD |
1328 | return -EFAULT; |
1329 | } | |
1330 | ||
1331 | /* | |
1332 | * If we are singlestepping, then ensure this thread is not connected to | |
1333 | * non-fatal signals until completion of singlestep. When xol insn itself | |
1334 | * triggers the signal, restart the original insn even if the task is | |
1335 | * already SIGKILL'ed (since coredump should report the correct ip). This | |
1336 | * is even more important if the task has a handler for SIGSEGV/etc, The | |
1337 | * _same_ instruction should be repeated again after return from the signal | |
1338 | * handler, and SSTEP can never finish in this case. | |
1339 | */ | |
1340 | bool uprobe_deny_signal(void) | |
1341 | { | |
1342 | struct task_struct *t = current; | |
1343 | struct uprobe_task *utask = t->utask; | |
1344 | ||
1345 | if (likely(!utask || !utask->active_uprobe)) | |
1346 | return false; | |
1347 | ||
1348 | WARN_ON_ONCE(utask->state != UTASK_SSTEP); | |
1349 | ||
1350 | if (signal_pending(t)) { | |
1351 | spin_lock_irq(&t->sighand->siglock); | |
1352 | clear_tsk_thread_flag(t, TIF_SIGPENDING); | |
1353 | spin_unlock_irq(&t->sighand->siglock); | |
1354 | ||
1355 | if (__fatal_signal_pending(t) || arch_uprobe_xol_was_trapped(t)) { | |
1356 | utask->state = UTASK_SSTEP_TRAPPED; | |
1357 | set_tsk_thread_flag(t, TIF_UPROBE); | |
1358 | set_tsk_thread_flag(t, TIF_NOTIFY_RESUME); | |
1359 | } | |
1360 | } | |
1361 | ||
1362 | return true; | |
1363 | } | |
1364 | ||
1365 | /* | |
1366 | * Avoid singlestepping the original instruction if the original instruction | |
1367 | * is a NOP or can be emulated. | |
1368 | */ | |
1369 | static bool can_skip_sstep(struct uprobe *uprobe, struct pt_regs *regs) | |
1370 | { | |
71434f2f | 1371 | if (test_bit(UPROBE_SKIP_SSTEP, &uprobe->flags)) { |
0578a970 ON |
1372 | if (arch_uprobe_skip_sstep(&uprobe->arch, regs)) |
1373 | return true; | |
71434f2f | 1374 | clear_bit(UPROBE_SKIP_SSTEP, &uprobe->flags); |
0578a970 | 1375 | } |
0326f5a9 SD |
1376 | return false; |
1377 | } | |
1378 | ||
499a4f3e ON |
1379 | static void mmf_recalc_uprobes(struct mm_struct *mm) |
1380 | { | |
1381 | struct vm_area_struct *vma; | |
1382 | ||
1383 | for (vma = mm->mmap; vma; vma = vma->vm_next) { | |
1384 | if (!valid_vma(vma, false)) | |
1385 | continue; | |
1386 | /* | |
1387 | * This is not strictly accurate, we can race with | |
1388 | * uprobe_unregister() and see the already removed | |
1389 | * uprobe if delete_uprobe() was not yet called. | |
63633cbf | 1390 | * Or this uprobe can be filtered out. |
499a4f3e ON |
1391 | */ |
1392 | if (vma_has_uprobes(vma, vma->vm_start, vma->vm_end)) | |
1393 | return; | |
1394 | } | |
1395 | ||
1396 | clear_bit(MMF_HAS_UPROBES, &mm->flags); | |
1397 | } | |
1398 | ||
ec75fba9 ON |
1399 | static int is_swbp_at_addr(struct mm_struct *mm, unsigned long vaddr) |
1400 | { | |
1401 | struct page *page; | |
1402 | uprobe_opcode_t opcode; | |
1403 | int result; | |
1404 | ||
1405 | pagefault_disable(); | |
1406 | result = __copy_from_user_inatomic(&opcode, (void __user*)vaddr, | |
1407 | sizeof(opcode)); | |
1408 | pagefault_enable(); | |
1409 | ||
1410 | if (likely(result == 0)) | |
1411 | goto out; | |
1412 | ||
1413 | result = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL); | |
1414 | if (result < 0) | |
1415 | return result; | |
1416 | ||
1417 | copy_opcode(page, vaddr, &opcode); | |
1418 | put_page(page); | |
1419 | out: | |
1420 | return is_swbp_insn(&opcode); | |
1421 | } | |
1422 | ||
d790d346 | 1423 | static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp) |
0326f5a9 | 1424 | { |
3a9ea052 ON |
1425 | struct mm_struct *mm = current->mm; |
1426 | struct uprobe *uprobe = NULL; | |
0326f5a9 | 1427 | struct vm_area_struct *vma; |
0326f5a9 | 1428 | |
0326f5a9 SD |
1429 | down_read(&mm->mmap_sem); |
1430 | vma = find_vma(mm, bp_vaddr); | |
3a9ea052 ON |
1431 | if (vma && vma->vm_start <= bp_vaddr) { |
1432 | if (valid_vma(vma, false)) { | |
cb113b47 ON |
1433 | struct inode *inode = vma->vm_file->f_mapping->host; |
1434 | loff_t offset = vaddr_to_offset(vma, bp_vaddr); | |
0326f5a9 | 1435 | |
3a9ea052 ON |
1436 | uprobe = find_uprobe(inode, offset); |
1437 | } | |
d790d346 ON |
1438 | |
1439 | if (!uprobe) | |
1440 | *is_swbp = is_swbp_at_addr(mm, bp_vaddr); | |
1441 | } else { | |
1442 | *is_swbp = -EFAULT; | |
0326f5a9 | 1443 | } |
499a4f3e ON |
1444 | |
1445 | if (!uprobe && test_and_clear_bit(MMF_RECALC_UPROBES, &mm->flags)) | |
1446 | mmf_recalc_uprobes(mm); | |
0326f5a9 SD |
1447 | up_read(&mm->mmap_sem); |
1448 | ||
3a9ea052 ON |
1449 | return uprobe; |
1450 | } | |
1451 | ||
1452 | /* | |
1453 | * Run handler and ask thread to singlestep. | |
1454 | * Ensure all non-fatal signals cannot interrupt thread while it singlesteps. | |
1455 | */ | |
1456 | static void handle_swbp(struct pt_regs *regs) | |
1457 | { | |
1458 | struct uprobe_task *utask; | |
1459 | struct uprobe *uprobe; | |
1460 | unsigned long bp_vaddr; | |
56bb4cf6 | 1461 | int uninitialized_var(is_swbp); |
3a9ea052 ON |
1462 | |
1463 | bp_vaddr = uprobe_get_swbp_addr(regs); | |
d790d346 | 1464 | uprobe = find_active_uprobe(bp_vaddr, &is_swbp); |
3a9ea052 | 1465 | |
0326f5a9 | 1466 | if (!uprobe) { |
56bb4cf6 ON |
1467 | if (is_swbp > 0) { |
1468 | /* No matching uprobe; signal SIGTRAP. */ | |
1469 | send_sig(SIGTRAP, current, 0); | |
1470 | } else { | |
1471 | /* | |
1472 | * Either we raced with uprobe_unregister() or we can't | |
1473 | * access this memory. The latter is only possible if | |
1474 | * another thread plays with our ->mm. In both cases | |
1475 | * we can simply restart. If this vma was unmapped we | |
1476 | * can pretend this insn was not executed yet and get | |
1477 | * the (correct) SIGSEGV after restart. | |
1478 | */ | |
1479 | instruction_pointer_set(regs, bp_vaddr); | |
1480 | } | |
0326f5a9 SD |
1481 | return; |
1482 | } | |
142b18dd ON |
1483 | /* |
1484 | * TODO: move copy_insn/etc into _register and remove this hack. | |
1485 | * After we hit the bp, _unregister + _register can install the | |
1486 | * new and not-yet-analyzed uprobe at the same address, restart. | |
1487 | */ | |
1488 | smp_rmb(); /* pairs with wmb() in install_breakpoint() */ | |
71434f2f | 1489 | if (unlikely(!test_bit(UPROBE_COPY_INSN, &uprobe->flags))) |
142b18dd | 1490 | goto restart; |
0326f5a9 SD |
1491 | |
1492 | utask = current->utask; | |
1493 | if (!utask) { | |
1494 | utask = add_utask(); | |
1495 | /* Cannot allocate; re-execute the instruction. */ | |
1496 | if (!utask) | |
0578a970 | 1497 | goto restart; |
0326f5a9 | 1498 | } |
746a9e6b | 1499 | |
0326f5a9 | 1500 | handler_chain(uprobe, regs); |
0578a970 ON |
1501 | if (can_skip_sstep(uprobe, regs)) |
1502 | goto out; | |
0326f5a9 | 1503 | |
0326f5a9 | 1504 | if (!pre_ssout(uprobe, regs, bp_vaddr)) { |
746a9e6b ON |
1505 | utask->active_uprobe = uprobe; |
1506 | utask->state = UTASK_SSTEP; | |
0326f5a9 SD |
1507 | return; |
1508 | } | |
1509 | ||
0578a970 ON |
1510 | restart: |
1511 | /* | |
1512 | * cannot singlestep; cannot skip instruction; | |
1513 | * re-execute the instruction. | |
1514 | */ | |
1515 | instruction_pointer_set(regs, bp_vaddr); | |
1516 | out: | |
8bd87445 | 1517 | put_uprobe(uprobe); |
0326f5a9 SD |
1518 | } |
1519 | ||
1520 | /* | |
1521 | * Perform required fix-ups and disable singlestep. | |
1522 | * Allow pending signals to take effect. | |
1523 | */ | |
1524 | static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs) | |
1525 | { | |
1526 | struct uprobe *uprobe; | |
1527 | ||
1528 | uprobe = utask->active_uprobe; | |
1529 | if (utask->state == UTASK_SSTEP_ACK) | |
1530 | arch_uprobe_post_xol(&uprobe->arch, regs); | |
1531 | else if (utask->state == UTASK_SSTEP_TRAPPED) | |
1532 | arch_uprobe_abort_xol(&uprobe->arch, regs); | |
1533 | else | |
1534 | WARN_ON_ONCE(1); | |
1535 | ||
1536 | put_uprobe(uprobe); | |
1537 | utask->active_uprobe = NULL; | |
1538 | utask->state = UTASK_RUNNING; | |
d4b3b638 | 1539 | xol_free_insn_slot(current); |
0326f5a9 SD |
1540 | |
1541 | spin_lock_irq(¤t->sighand->siglock); | |
1542 | recalc_sigpending(); /* see uprobe_deny_signal() */ | |
1543 | spin_unlock_irq(¤t->sighand->siglock); | |
1544 | } | |
1545 | ||
1546 | /* | |
1b08e907 ON |
1547 | * On breakpoint hit, breakpoint notifier sets the TIF_UPROBE flag and |
1548 | * allows the thread to return from interrupt. After that handle_swbp() | |
1549 | * sets utask->active_uprobe. | |
0326f5a9 | 1550 | * |
1b08e907 ON |
1551 | * On singlestep exception, singlestep notifier sets the TIF_UPROBE flag |
1552 | * and allows the thread to return from interrupt. | |
0326f5a9 SD |
1553 | * |
1554 | * While returning to userspace, thread notices the TIF_UPROBE flag and calls | |
1555 | * uprobe_notify_resume(). | |
1556 | */ | |
1557 | void uprobe_notify_resume(struct pt_regs *regs) | |
1558 | { | |
1559 | struct uprobe_task *utask; | |
1560 | ||
db023ea5 ON |
1561 | clear_thread_flag(TIF_UPROBE); |
1562 | ||
0326f5a9 | 1563 | utask = current->utask; |
1b08e907 | 1564 | if (utask && utask->active_uprobe) |
0326f5a9 | 1565 | handle_singlestep(utask, regs); |
1b08e907 ON |
1566 | else |
1567 | handle_swbp(regs); | |
0326f5a9 SD |
1568 | } |
1569 | ||
1570 | /* | |
1571 | * uprobe_pre_sstep_notifier gets called from interrupt context as part of | |
1572 | * notifier mechanism. Set TIF_UPROBE flag and indicate breakpoint hit. | |
1573 | */ | |
1574 | int uprobe_pre_sstep_notifier(struct pt_regs *regs) | |
1575 | { | |
f8ac4ec9 | 1576 | if (!current->mm || !test_bit(MMF_HAS_UPROBES, ¤t->mm->flags)) |
0326f5a9 SD |
1577 | return 0; |
1578 | ||
0326f5a9 | 1579 | set_thread_flag(TIF_UPROBE); |
0326f5a9 SD |
1580 | return 1; |
1581 | } | |
1582 | ||
1583 | /* | |
1584 | * uprobe_post_sstep_notifier gets called in interrupt context as part of notifier | |
1585 | * mechanism. Set TIF_UPROBE flag and indicate completion of singlestep. | |
1586 | */ | |
1587 | int uprobe_post_sstep_notifier(struct pt_regs *regs) | |
1588 | { | |
1589 | struct uprobe_task *utask = current->utask; | |
1590 | ||
1591 | if (!current->mm || !utask || !utask->active_uprobe) | |
1592 | /* task is currently not uprobed */ | |
1593 | return 0; | |
1594 | ||
1595 | utask->state = UTASK_SSTEP_ACK; | |
1596 | set_thread_flag(TIF_UPROBE); | |
1597 | return 1; | |
1598 | } | |
1599 | ||
1600 | static struct notifier_block uprobe_exception_nb = { | |
1601 | .notifier_call = arch_uprobe_exception_notify, | |
1602 | .priority = INT_MAX-1, /* notified after kprobes, kgdb */ | |
1603 | }; | |
1604 | ||
2b144498 SD |
1605 | static int __init init_uprobes(void) |
1606 | { | |
1607 | int i; | |
1608 | ||
1609 | for (i = 0; i < UPROBES_HASH_SZ; i++) { | |
1610 | mutex_init(&uprobes_mutex[i]); | |
1611 | mutex_init(&uprobes_mmap_mutex[i]); | |
1612 | } | |
0326f5a9 | 1613 | |
32cdba1e ON |
1614 | if (percpu_init_rwsem(&dup_mmap_sem)) |
1615 | return -ENOMEM; | |
1616 | ||
0326f5a9 | 1617 | return register_die_notifier(&uprobe_exception_nb); |
2b144498 | 1618 | } |
0326f5a9 | 1619 | module_init(init_uprobes); |
2b144498 SD |
1620 | |
1621 | static void __exit exit_uprobes(void) | |
1622 | { | |
1623 | } | |
2b144498 | 1624 | module_exit(exit_uprobes); |