]>
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> | |
e8440c14 | 30 | #include <linux/export.h> |
2b144498 SD |
31 | #include <linux/rmap.h> /* anon_vma_prepare */ |
32 | #include <linux/mmu_notifier.h> /* set_pte_at_notify */ | |
33 | #include <linux/swap.h> /* try_to_free_swap */ | |
0326f5a9 SD |
34 | #include <linux/ptrace.h> /* user_enable_single_step */ |
35 | #include <linux/kdebug.h> /* notifier mechanism */ | |
194f8dcb | 36 | #include "../../mm/internal.h" /* munlock_vma_page */ |
32cdba1e | 37 | #include <linux/percpu-rwsem.h> |
7b2d81d4 | 38 | |
2b144498 SD |
39 | #include <linux/uprobes.h> |
40 | ||
d4b3b638 SD |
41 | #define UINSNS_PER_PAGE (PAGE_SIZE/UPROBE_XOL_SLOT_BYTES) |
42 | #define MAX_UPROBE_XOL_SLOTS UINSNS_PER_PAGE | |
43 | ||
2b144498 | 44 | static struct rb_root uprobes_tree = RB_ROOT; |
441f1eb7 ON |
45 | /* |
46 | * allows us to skip the uprobe_mmap if there are no uprobe events active | |
47 | * at this time. Probably a fine grained per inode count is better? | |
48 | */ | |
49 | #define no_uprobe_events() RB_EMPTY_ROOT(&uprobes_tree) | |
7b2d81d4 | 50 | |
2b144498 SD |
51 | static DEFINE_SPINLOCK(uprobes_treelock); /* serialize rbtree access */ |
52 | ||
53 | #define UPROBES_HASH_SZ 13 | |
2b144498 SD |
54 | /* serialize uprobe->pending_list */ |
55 | static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ]; | |
7b2d81d4 | 56 | #define uprobes_mmap_hash(v) (&uprobes_mmap_mutex[((unsigned long)(v)) % UPROBES_HASH_SZ]) |
2b144498 | 57 | |
32cdba1e ON |
58 | static struct percpu_rw_semaphore dup_mmap_sem; |
59 | ||
cb9a19fe | 60 | /* Have a copy of original instruction */ |
71434f2f | 61 | #define UPROBE_COPY_INSN 0 |
cb9a19fe | 62 | /* Can skip singlestep */ |
bb929284 | 63 | #define UPROBE_SKIP_SSTEP 1 |
cb9a19fe | 64 | |
3ff54efd SD |
65 | struct uprobe { |
66 | struct rb_node rb_node; /* node in the rb tree */ | |
67 | atomic_t ref; | |
e591c8d7 | 68 | struct rw_semaphore register_rwsem; |
3ff54efd SD |
69 | struct rw_semaphore consumer_rwsem; |
70 | struct list_head pending_list; | |
71 | struct uprobe_consumer *consumers; | |
72 | struct inode *inode; /* Also hold a ref to inode */ | |
73 | loff_t offset; | |
71434f2f | 74 | unsigned long flags; |
3ff54efd SD |
75 | struct arch_uprobe arch; |
76 | }; | |
77 | ||
0dfd0eb8 AA |
78 | struct return_instance { |
79 | struct uprobe *uprobe; | |
80 | unsigned long func; | |
81 | unsigned long orig_ret_vaddr; /* original return address */ | |
82 | bool chained; /* true, if instance is nested */ | |
83 | ||
84 | struct return_instance *next; /* keep as stack */ | |
85 | }; | |
86 | ||
2b144498 SD |
87 | /* |
88 | * valid_vma: Verify if the specified vma is an executable vma | |
89 | * Relax restrictions while unregistering: vm_flags might have | |
90 | * changed after breakpoint was inserted. | |
91 | * - is_register: indicates if we are in register context. | |
92 | * - Return 1 if the specified virtual address is in an | |
93 | * executable vma. | |
94 | */ | |
95 | static bool valid_vma(struct vm_area_struct *vma, bool is_register) | |
96 | { | |
e40cfce6 | 97 | vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_SHARED; |
2b144498 | 98 | |
e40cfce6 ON |
99 | if (is_register) |
100 | flags |= VM_WRITE; | |
2b144498 | 101 | |
e40cfce6 | 102 | return vma->vm_file && (vma->vm_flags & flags) == VM_MAYEXEC; |
2b144498 SD |
103 | } |
104 | ||
57683f72 | 105 | static unsigned long offset_to_vaddr(struct vm_area_struct *vma, loff_t offset) |
2b144498 | 106 | { |
57683f72 | 107 | return vma->vm_start + offset - ((loff_t)vma->vm_pgoff << PAGE_SHIFT); |
2b144498 SD |
108 | } |
109 | ||
cb113b47 ON |
110 | static loff_t vaddr_to_offset(struct vm_area_struct *vma, unsigned long vaddr) |
111 | { | |
112 | return ((loff_t)vma->vm_pgoff << PAGE_SHIFT) + (vaddr - vma->vm_start); | |
113 | } | |
114 | ||
2b144498 SD |
115 | /** |
116 | * __replace_page - replace page in vma by new page. | |
117 | * based on replace_page in mm/ksm.c | |
118 | * | |
119 | * @vma: vma that holds the pte pointing to page | |
c517ee74 | 120 | * @addr: address the old @page is mapped at |
2b144498 SD |
121 | * @page: the cowed page we are replacing by kpage |
122 | * @kpage: the modified page we replace page by | |
123 | * | |
124 | * Returns 0 on success, -EFAULT on failure. | |
125 | */ | |
c517ee74 ON |
126 | static int __replace_page(struct vm_area_struct *vma, unsigned long addr, |
127 | struct page *page, struct page *kpage) | |
2b144498 SD |
128 | { |
129 | struct mm_struct *mm = vma->vm_mm; | |
5323ce71 ON |
130 | spinlock_t *ptl; |
131 | pte_t *ptep; | |
9f92448c | 132 | int err; |
6bdb913f HE |
133 | /* For mmu_notifiers */ |
134 | const unsigned long mmun_start = addr; | |
135 | const unsigned long mmun_end = addr + PAGE_SIZE; | |
2b144498 | 136 | |
194f8dcb | 137 | /* For try_to_free_swap() and munlock_vma_page() below */ |
9f92448c ON |
138 | lock_page(page); |
139 | ||
6bdb913f | 140 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); |
9f92448c | 141 | err = -EAGAIN; |
5323ce71 | 142 | ptep = page_check_address(page, mm, addr, &ptl, 0); |
2b144498 | 143 | if (!ptep) |
9f92448c | 144 | goto unlock; |
2b144498 SD |
145 | |
146 | get_page(kpage); | |
147 | page_add_new_anon_rmap(kpage, vma, addr); | |
148 | ||
7396fa81 SD |
149 | if (!PageAnon(page)) { |
150 | dec_mm_counter(mm, MM_FILEPAGES); | |
151 | inc_mm_counter(mm, MM_ANONPAGES); | |
152 | } | |
153 | ||
2b144498 SD |
154 | flush_cache_page(vma, addr, pte_pfn(*ptep)); |
155 | ptep_clear_flush(vma, addr, ptep); | |
156 | set_pte_at_notify(mm, addr, ptep, mk_pte(kpage, vma->vm_page_prot)); | |
157 | ||
158 | page_remove_rmap(page); | |
159 | if (!page_mapped(page)) | |
160 | try_to_free_swap(page); | |
2b144498 | 161 | pte_unmap_unlock(ptep, ptl); |
2b144498 | 162 | |
194f8dcb ON |
163 | if (vma->vm_flags & VM_LOCKED) |
164 | munlock_vma_page(page); | |
165 | put_page(page); | |
166 | ||
9f92448c ON |
167 | err = 0; |
168 | unlock: | |
6bdb913f | 169 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
9f92448c ON |
170 | unlock_page(page); |
171 | return err; | |
2b144498 SD |
172 | } |
173 | ||
174 | /** | |
5cb4ac3a | 175 | * is_swbp_insn - check if instruction is breakpoint instruction. |
2b144498 | 176 | * @insn: instruction to be checked. |
5cb4ac3a | 177 | * Default implementation of is_swbp_insn |
2b144498 SD |
178 | * Returns true if @insn is a breakpoint instruction. |
179 | */ | |
5cb4ac3a | 180 | bool __weak is_swbp_insn(uprobe_opcode_t *insn) |
2b144498 | 181 | { |
5cb4ac3a | 182 | return *insn == UPROBE_SWBP_INSN; |
2b144498 SD |
183 | } |
184 | ||
0908ad6e AM |
185 | /** |
186 | * is_trap_insn - check if instruction is breakpoint instruction. | |
187 | * @insn: instruction to be checked. | |
188 | * Default implementation of is_trap_insn | |
189 | * Returns true if @insn is a breakpoint instruction. | |
190 | * | |
191 | * This function is needed for the case where an architecture has multiple | |
192 | * trap instructions (like powerpc). | |
193 | */ | |
194 | bool __weak is_trap_insn(uprobe_opcode_t *insn) | |
195 | { | |
196 | return is_swbp_insn(insn); | |
197 | } | |
198 | ||
ab0d805c | 199 | static void copy_from_page(struct page *page, unsigned long vaddr, void *dst, int len) |
cceb55aa ON |
200 | { |
201 | void *kaddr = kmap_atomic(page); | |
ab0d805c | 202 | memcpy(dst, kaddr + (vaddr & ~PAGE_MASK), len); |
cceb55aa ON |
203 | kunmap_atomic(kaddr); |
204 | } | |
205 | ||
5669ccee ON |
206 | static void copy_to_page(struct page *page, unsigned long vaddr, const void *src, int len) |
207 | { | |
208 | void *kaddr = kmap_atomic(page); | |
209 | memcpy(kaddr + (vaddr & ~PAGE_MASK), src, len); | |
210 | kunmap_atomic(kaddr); | |
211 | } | |
212 | ||
ed6f6a50 ON |
213 | static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *new_opcode) |
214 | { | |
215 | uprobe_opcode_t old_opcode; | |
216 | bool is_swbp; | |
217 | ||
0908ad6e AM |
218 | /* |
219 | * Note: We only check if the old_opcode is UPROBE_SWBP_INSN here. | |
220 | * We do not check if it is any other 'trap variant' which could | |
221 | * be conditional trap instruction such as the one powerpc supports. | |
222 | * | |
223 | * The logic is that we do not care if the underlying instruction | |
224 | * is a trap variant; uprobes always wins over any other (gdb) | |
225 | * breakpoint. | |
226 | */ | |
ab0d805c | 227 | copy_from_page(page, vaddr, &old_opcode, UPROBE_SWBP_INSN_SIZE); |
ed6f6a50 ON |
228 | is_swbp = is_swbp_insn(&old_opcode); |
229 | ||
230 | if (is_swbp_insn(new_opcode)) { | |
231 | if (is_swbp) /* register: already installed? */ | |
232 | return 0; | |
233 | } else { | |
234 | if (!is_swbp) /* unregister: was it changed by us? */ | |
076a365b | 235 | return 0; |
ed6f6a50 ON |
236 | } |
237 | ||
238 | return 1; | |
239 | } | |
240 | ||
2b144498 SD |
241 | /* |
242 | * NOTE: | |
243 | * Expect the breakpoint instruction to be the smallest size instruction for | |
244 | * the architecture. If an arch has variable length instruction and the | |
245 | * breakpoint instruction is not of the smallest length instruction | |
0908ad6e | 246 | * supported by that architecture then we need to modify is_trap_at_addr and |
2b144498 SD |
247 | * write_opcode accordingly. This would never be a problem for archs that |
248 | * have fixed length instructions. | |
249 | */ | |
250 | ||
251 | /* | |
252 | * write_opcode - write the opcode at a given virtual address. | |
253 | * @mm: the probed process address space. | |
2b144498 SD |
254 | * @vaddr: the virtual address to store the opcode. |
255 | * @opcode: opcode to be written at @vaddr. | |
256 | * | |
257 | * Called with mm->mmap_sem held (for read and with a reference to | |
258 | * mm). | |
259 | * | |
260 | * For mm @mm, write the opcode at @vaddr. | |
261 | * Return 0 (success) or a negative errno. | |
262 | */ | |
cceb55aa ON |
263 | static int write_opcode(struct mm_struct *mm, unsigned long vaddr, |
264 | uprobe_opcode_t opcode) | |
2b144498 SD |
265 | { |
266 | struct page *old_page, *new_page; | |
2b144498 | 267 | struct vm_area_struct *vma; |
2b144498 | 268 | int ret; |
f403072c | 269 | |
5323ce71 | 270 | retry: |
2b144498 | 271 | /* Read the page with vaddr into memory */ |
75ed82ea | 272 | ret = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &old_page, &vma); |
2b144498 SD |
273 | if (ret <= 0) |
274 | return ret; | |
7b2d81d4 | 275 | |
ed6f6a50 ON |
276 | ret = verify_opcode(old_page, vaddr, &opcode); |
277 | if (ret <= 0) | |
278 | goto put_old; | |
279 | ||
2b144498 SD |
280 | ret = -ENOMEM; |
281 | new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr); | |
282 | if (!new_page) | |
9f92448c | 283 | goto put_old; |
2b144498 SD |
284 | |
285 | __SetPageUptodate(new_page); | |
286 | ||
3f47107c ON |
287 | copy_highpage(new_page, old_page); |
288 | copy_to_page(new_page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE); | |
2b144498 SD |
289 | |
290 | ret = anon_vma_prepare(vma); | |
291 | if (ret) | |
9f92448c | 292 | goto put_new; |
2b144498 | 293 | |
c517ee74 | 294 | ret = __replace_page(vma, vaddr, old_page, new_page); |
2b144498 | 295 | |
9f92448c | 296 | put_new: |
2b144498 | 297 | page_cache_release(new_page); |
9f92448c | 298 | put_old: |
7b2d81d4 IM |
299 | put_page(old_page); |
300 | ||
5323ce71 ON |
301 | if (unlikely(ret == -EAGAIN)) |
302 | goto retry; | |
2b144498 SD |
303 | return ret; |
304 | } | |
305 | ||
2b144498 | 306 | /** |
5cb4ac3a | 307 | * set_swbp - store breakpoint at a given address. |
e3343e6a | 308 | * @auprobe: arch specific probepoint information. |
2b144498 | 309 | * @mm: the probed process address space. |
2b144498 SD |
310 | * @vaddr: the virtual address to insert the opcode. |
311 | * | |
312 | * For mm @mm, store the breakpoint instruction at @vaddr. | |
313 | * Return 0 (success) or a negative errno. | |
314 | */ | |
5cb4ac3a | 315 | int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) |
2b144498 | 316 | { |
cceb55aa | 317 | return write_opcode(mm, vaddr, UPROBE_SWBP_INSN); |
2b144498 SD |
318 | } |
319 | ||
320 | /** | |
321 | * set_orig_insn - Restore the original instruction. | |
322 | * @mm: the probed process address space. | |
e3343e6a | 323 | * @auprobe: arch specific probepoint information. |
2b144498 | 324 | * @vaddr: the virtual address to insert the opcode. |
2b144498 SD |
325 | * |
326 | * For mm @mm, restore the original opcode (opcode) at @vaddr. | |
327 | * Return 0 (success) or a negative errno. | |
328 | */ | |
7b2d81d4 | 329 | int __weak |
ded86e7c | 330 | set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) |
2b144498 | 331 | { |
cceb55aa | 332 | return write_opcode(mm, vaddr, *(uprobe_opcode_t *)auprobe->insn); |
2b144498 SD |
333 | } |
334 | ||
335 | static int match_uprobe(struct uprobe *l, struct uprobe *r) | |
336 | { | |
337 | if (l->inode < r->inode) | |
338 | return -1; | |
7b2d81d4 | 339 | |
2b144498 SD |
340 | if (l->inode > r->inode) |
341 | return 1; | |
2b144498 | 342 | |
7b2d81d4 IM |
343 | if (l->offset < r->offset) |
344 | return -1; | |
345 | ||
346 | if (l->offset > r->offset) | |
347 | return 1; | |
2b144498 SD |
348 | |
349 | return 0; | |
350 | } | |
351 | ||
352 | static struct uprobe *__find_uprobe(struct inode *inode, loff_t offset) | |
353 | { | |
354 | struct uprobe u = { .inode = inode, .offset = offset }; | |
355 | struct rb_node *n = uprobes_tree.rb_node; | |
356 | struct uprobe *uprobe; | |
357 | int match; | |
358 | ||
359 | while (n) { | |
360 | uprobe = rb_entry(n, struct uprobe, rb_node); | |
361 | match = match_uprobe(&u, uprobe); | |
362 | if (!match) { | |
363 | atomic_inc(&uprobe->ref); | |
364 | return uprobe; | |
365 | } | |
7b2d81d4 | 366 | |
2b144498 SD |
367 | if (match < 0) |
368 | n = n->rb_left; | |
369 | else | |
370 | n = n->rb_right; | |
371 | } | |
372 | return NULL; | |
373 | } | |
374 | ||
375 | /* | |
376 | * Find a uprobe corresponding to a given inode:offset | |
377 | * Acquires uprobes_treelock | |
378 | */ | |
379 | static struct uprobe *find_uprobe(struct inode *inode, loff_t offset) | |
380 | { | |
381 | struct uprobe *uprobe; | |
2b144498 | 382 | |
6f47caa0 | 383 | spin_lock(&uprobes_treelock); |
2b144498 | 384 | uprobe = __find_uprobe(inode, offset); |
6f47caa0 | 385 | spin_unlock(&uprobes_treelock); |
7b2d81d4 | 386 | |
2b144498 SD |
387 | return uprobe; |
388 | } | |
389 | ||
390 | static struct uprobe *__insert_uprobe(struct uprobe *uprobe) | |
391 | { | |
392 | struct rb_node **p = &uprobes_tree.rb_node; | |
393 | struct rb_node *parent = NULL; | |
394 | struct uprobe *u; | |
395 | int match; | |
396 | ||
397 | while (*p) { | |
398 | parent = *p; | |
399 | u = rb_entry(parent, struct uprobe, rb_node); | |
400 | match = match_uprobe(uprobe, u); | |
401 | if (!match) { | |
402 | atomic_inc(&u->ref); | |
403 | return u; | |
404 | } | |
405 | ||
406 | if (match < 0) | |
407 | p = &parent->rb_left; | |
408 | else | |
409 | p = &parent->rb_right; | |
410 | ||
411 | } | |
7b2d81d4 | 412 | |
2b144498 SD |
413 | u = NULL; |
414 | rb_link_node(&uprobe->rb_node, parent, p); | |
415 | rb_insert_color(&uprobe->rb_node, &uprobes_tree); | |
416 | /* get access + creation ref */ | |
417 | atomic_set(&uprobe->ref, 2); | |
7b2d81d4 | 418 | |
2b144498 SD |
419 | return u; |
420 | } | |
421 | ||
422 | /* | |
7b2d81d4 | 423 | * Acquire uprobes_treelock. |
2b144498 SD |
424 | * Matching uprobe already exists in rbtree; |
425 | * increment (access refcount) and return the matching uprobe. | |
426 | * | |
427 | * No matching uprobe; insert the uprobe in rb_tree; | |
428 | * get a double refcount (access + creation) and return NULL. | |
429 | */ | |
430 | static struct uprobe *insert_uprobe(struct uprobe *uprobe) | |
431 | { | |
2b144498 SD |
432 | struct uprobe *u; |
433 | ||
6f47caa0 | 434 | spin_lock(&uprobes_treelock); |
2b144498 | 435 | u = __insert_uprobe(uprobe); |
6f47caa0 | 436 | spin_unlock(&uprobes_treelock); |
7b2d81d4 | 437 | |
2b144498 SD |
438 | return u; |
439 | } | |
440 | ||
441 | static void put_uprobe(struct uprobe *uprobe) | |
442 | { | |
443 | if (atomic_dec_and_test(&uprobe->ref)) | |
444 | kfree(uprobe); | |
445 | } | |
446 | ||
447 | static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) | |
448 | { | |
449 | struct uprobe *uprobe, *cur_uprobe; | |
450 | ||
451 | uprobe = kzalloc(sizeof(struct uprobe), GFP_KERNEL); | |
452 | if (!uprobe) | |
453 | return NULL; | |
454 | ||
455 | uprobe->inode = igrab(inode); | |
456 | uprobe->offset = offset; | |
e591c8d7 | 457 | init_rwsem(&uprobe->register_rwsem); |
2b144498 | 458 | init_rwsem(&uprobe->consumer_rwsem); |
bbc33d05 ON |
459 | /* For now assume that the instruction need not be single-stepped */ |
460 | __set_bit(UPROBE_SKIP_SSTEP, &uprobe->flags); | |
2b144498 SD |
461 | |
462 | /* add to uprobes_tree, sorted on inode:offset */ | |
463 | cur_uprobe = insert_uprobe(uprobe); | |
464 | ||
465 | /* a uprobe exists for this inode:offset combination */ | |
466 | if (cur_uprobe) { | |
467 | kfree(uprobe); | |
468 | uprobe = cur_uprobe; | |
469 | iput(inode); | |
7b2d81d4 IM |
470 | } |
471 | ||
2b144498 SD |
472 | return uprobe; |
473 | } | |
474 | ||
9a98e03c | 475 | static void consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc) |
2b144498 SD |
476 | { |
477 | down_write(&uprobe->consumer_rwsem); | |
e3343e6a SD |
478 | uc->next = uprobe->consumers; |
479 | uprobe->consumers = uc; | |
2b144498 | 480 | up_write(&uprobe->consumer_rwsem); |
2b144498 SD |
481 | } |
482 | ||
483 | /* | |
e3343e6a SD |
484 | * For uprobe @uprobe, delete the consumer @uc. |
485 | * Return true if the @uc is deleted successfully | |
2b144498 SD |
486 | * or return false. |
487 | */ | |
e3343e6a | 488 | static bool consumer_del(struct uprobe *uprobe, struct uprobe_consumer *uc) |
2b144498 SD |
489 | { |
490 | struct uprobe_consumer **con; | |
491 | bool ret = false; | |
492 | ||
493 | down_write(&uprobe->consumer_rwsem); | |
494 | for (con = &uprobe->consumers; *con; con = &(*con)->next) { | |
e3343e6a SD |
495 | if (*con == uc) { |
496 | *con = uc->next; | |
2b144498 SD |
497 | ret = true; |
498 | break; | |
499 | } | |
500 | } | |
501 | up_write(&uprobe->consumer_rwsem); | |
7b2d81d4 | 502 | |
2b144498 SD |
503 | return ret; |
504 | } | |
505 | ||
e3343e6a | 506 | static int |
d436615e | 507 | __copy_insn(struct address_space *mapping, struct file *filp, char *insn, |
593609a5 | 508 | unsigned long nbytes, loff_t offset) |
2b144498 | 509 | { |
2b144498 | 510 | struct page *page; |
2b144498 | 511 | |
cc359d18 ON |
512 | if (!mapping->a_ops->readpage) |
513 | return -EIO; | |
2b144498 SD |
514 | /* |
515 | * Ensure that the page that has the original instruction is | |
516 | * populated and in page-cache. | |
517 | */ | |
2edb7b55 | 518 | page = read_mapping_page(mapping, offset >> PAGE_CACHE_SHIFT, filp); |
2b144498 SD |
519 | if (IS_ERR(page)) |
520 | return PTR_ERR(page); | |
521 | ||
2edb7b55 | 522 | copy_from_page(page, offset, insn, nbytes); |
2b144498 | 523 | page_cache_release(page); |
7b2d81d4 | 524 | |
2b144498 SD |
525 | return 0; |
526 | } | |
527 | ||
d436615e | 528 | static int copy_insn(struct uprobe *uprobe, struct file *filp) |
2b144498 SD |
529 | { |
530 | struct address_space *mapping; | |
2b144498 | 531 | unsigned long nbytes; |
7b2d81d4 | 532 | int bytes; |
2b144498 | 533 | |
d436615e | 534 | nbytes = PAGE_SIZE - (uprobe->offset & ~PAGE_MASK); |
2b144498 SD |
535 | mapping = uprobe->inode->i_mapping; |
536 | ||
537 | /* Instruction at end of binary; copy only available bytes */ | |
538 | if (uprobe->offset + MAX_UINSN_BYTES > uprobe->inode->i_size) | |
539 | bytes = uprobe->inode->i_size - uprobe->offset; | |
540 | else | |
541 | bytes = MAX_UINSN_BYTES; | |
542 | ||
543 | /* Instruction at the page-boundary; copy bytes in second page */ | |
544 | if (nbytes < bytes) { | |
fc36f595 ON |
545 | int err = __copy_insn(mapping, filp, uprobe->arch.insn + nbytes, |
546 | bytes - nbytes, uprobe->offset + nbytes); | |
547 | if (err) | |
548 | return err; | |
2b144498 SD |
549 | bytes = nbytes; |
550 | } | |
d436615e | 551 | return __copy_insn(mapping, filp, uprobe->arch.insn, bytes, uprobe->offset); |
2b144498 SD |
552 | } |
553 | ||
cb9a19fe ON |
554 | static int prepare_uprobe(struct uprobe *uprobe, struct file *file, |
555 | struct mm_struct *mm, unsigned long vaddr) | |
556 | { | |
557 | int ret = 0; | |
558 | ||
71434f2f | 559 | if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) |
cb9a19fe ON |
560 | return ret; |
561 | ||
d4d3ccc6 ON |
562 | /* TODO: move this into _register, until then we abuse this sem. */ |
563 | down_write(&uprobe->consumer_rwsem); | |
71434f2f | 564 | if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) |
4710f05f ON |
565 | goto out; |
566 | ||
cb9a19fe ON |
567 | ret = copy_insn(uprobe, file); |
568 | if (ret) | |
569 | goto out; | |
570 | ||
571 | ret = -ENOTSUPP; | |
0908ad6e | 572 | if (is_trap_insn((uprobe_opcode_t *)uprobe->arch.insn)) |
cb9a19fe ON |
573 | goto out; |
574 | ||
575 | ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, vaddr); | |
576 | if (ret) | |
577 | goto out; | |
578 | ||
579 | /* write_opcode() assumes we don't cross page boundary */ | |
580 | BUG_ON((uprobe->offset & ~PAGE_MASK) + | |
581 | UPROBE_SWBP_INSN_SIZE > PAGE_SIZE); | |
582 | ||
583 | smp_wmb(); /* pairs with rmb() in find_active_uprobe() */ | |
71434f2f | 584 | set_bit(UPROBE_COPY_INSN, &uprobe->flags); |
cb9a19fe ON |
585 | |
586 | out: | |
d4d3ccc6 | 587 | up_write(&uprobe->consumer_rwsem); |
4710f05f | 588 | |
cb9a19fe ON |
589 | return ret; |
590 | } | |
591 | ||
8a7f2fa0 ON |
592 | static inline bool consumer_filter(struct uprobe_consumer *uc, |
593 | enum uprobe_filter_ctx ctx, struct mm_struct *mm) | |
806a98bd | 594 | { |
8a7f2fa0 | 595 | return !uc->filter || uc->filter(uc, ctx, mm); |
806a98bd ON |
596 | } |
597 | ||
8a7f2fa0 ON |
598 | static bool filter_chain(struct uprobe *uprobe, |
599 | enum uprobe_filter_ctx ctx, struct mm_struct *mm) | |
63633cbf | 600 | { |
1ff6fee5 ON |
601 | struct uprobe_consumer *uc; |
602 | bool ret = false; | |
603 | ||
604 | down_read(&uprobe->consumer_rwsem); | |
605 | for (uc = uprobe->consumers; uc; uc = uc->next) { | |
8a7f2fa0 | 606 | ret = consumer_filter(uc, ctx, mm); |
1ff6fee5 ON |
607 | if (ret) |
608 | break; | |
609 | } | |
610 | up_read(&uprobe->consumer_rwsem); | |
611 | ||
612 | return ret; | |
63633cbf ON |
613 | } |
614 | ||
e3343e6a SD |
615 | static int |
616 | install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, | |
816c03fb | 617 | struct vm_area_struct *vma, unsigned long vaddr) |
2b144498 | 618 | { |
f8ac4ec9 | 619 | bool first_uprobe; |
2b144498 SD |
620 | int ret; |
621 | ||
cb9a19fe ON |
622 | ret = prepare_uprobe(uprobe, vma->vm_file, mm, vaddr); |
623 | if (ret) | |
624 | return ret; | |
682968e0 | 625 | |
f8ac4ec9 ON |
626 | /* |
627 | * set MMF_HAS_UPROBES in advance for uprobe_pre_sstep_notifier(), | |
628 | * the task can hit this breakpoint right after __replace_page(). | |
629 | */ | |
630 | first_uprobe = !test_bit(MMF_HAS_UPROBES, &mm->flags); | |
631 | if (first_uprobe) | |
632 | set_bit(MMF_HAS_UPROBES, &mm->flags); | |
633 | ||
816c03fb | 634 | ret = set_swbp(&uprobe->arch, mm, vaddr); |
9f68f672 ON |
635 | if (!ret) |
636 | clear_bit(MMF_RECALC_UPROBES, &mm->flags); | |
637 | else if (first_uprobe) | |
f8ac4ec9 | 638 | clear_bit(MMF_HAS_UPROBES, &mm->flags); |
2b144498 SD |
639 | |
640 | return ret; | |
641 | } | |
642 | ||
076a365b | 643 | static int |
816c03fb | 644 | remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr) |
2b144498 | 645 | { |
9f68f672 | 646 | set_bit(MMF_RECALC_UPROBES, &mm->flags); |
076a365b | 647 | return set_orig_insn(&uprobe->arch, mm, vaddr); |
2b144498 SD |
648 | } |
649 | ||
06b7bcd8 ON |
650 | static inline bool uprobe_is_active(struct uprobe *uprobe) |
651 | { | |
652 | return !RB_EMPTY_NODE(&uprobe->rb_node); | |
653 | } | |
0326f5a9 | 654 | /* |
778b032d ON |
655 | * There could be threads that have already hit the breakpoint. They |
656 | * will recheck the current insn and restart if find_uprobe() fails. | |
657 | * See find_active_uprobe(). | |
0326f5a9 | 658 | */ |
2b144498 SD |
659 | static void delete_uprobe(struct uprobe *uprobe) |
660 | { | |
06b7bcd8 ON |
661 | if (WARN_ON(!uprobe_is_active(uprobe))) |
662 | return; | |
663 | ||
6f47caa0 | 664 | spin_lock(&uprobes_treelock); |
2b144498 | 665 | rb_erase(&uprobe->rb_node, &uprobes_tree); |
6f47caa0 | 666 | spin_unlock(&uprobes_treelock); |
06b7bcd8 | 667 | RB_CLEAR_NODE(&uprobe->rb_node); /* for uprobe_is_active() */ |
2b144498 SD |
668 | iput(uprobe->inode); |
669 | put_uprobe(uprobe); | |
2b144498 SD |
670 | } |
671 | ||
26872090 ON |
672 | struct map_info { |
673 | struct map_info *next; | |
674 | struct mm_struct *mm; | |
816c03fb | 675 | unsigned long vaddr; |
26872090 ON |
676 | }; |
677 | ||
678 | static inline struct map_info *free_map_info(struct map_info *info) | |
2b144498 | 679 | { |
26872090 ON |
680 | struct map_info *next = info->next; |
681 | kfree(info); | |
682 | return next; | |
683 | } | |
684 | ||
685 | static struct map_info * | |
686 | build_map_info(struct address_space *mapping, loff_t offset, bool is_register) | |
687 | { | |
688 | unsigned long pgoff = offset >> PAGE_SHIFT; | |
2b144498 | 689 | struct vm_area_struct *vma; |
26872090 ON |
690 | struct map_info *curr = NULL; |
691 | struct map_info *prev = NULL; | |
692 | struct map_info *info; | |
693 | int more = 0; | |
2b144498 | 694 | |
26872090 ON |
695 | again: |
696 | mutex_lock(&mapping->i_mmap_mutex); | |
6b2dbba8 | 697 | vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { |
2b144498 SD |
698 | if (!valid_vma(vma, is_register)) |
699 | continue; | |
700 | ||
7a5bfb66 ON |
701 | if (!prev && !more) { |
702 | /* | |
703 | * Needs GFP_NOWAIT to avoid i_mmap_mutex recursion through | |
704 | * reclaim. This is optimistic, no harm done if it fails. | |
705 | */ | |
706 | prev = kmalloc(sizeof(struct map_info), | |
707 | GFP_NOWAIT | __GFP_NOMEMALLOC | __GFP_NOWARN); | |
708 | if (prev) | |
709 | prev->next = NULL; | |
710 | } | |
26872090 ON |
711 | if (!prev) { |
712 | more++; | |
713 | continue; | |
2b144498 | 714 | } |
2b144498 | 715 | |
26872090 ON |
716 | if (!atomic_inc_not_zero(&vma->vm_mm->mm_users)) |
717 | continue; | |
7b2d81d4 | 718 | |
26872090 ON |
719 | info = prev; |
720 | prev = prev->next; | |
721 | info->next = curr; | |
722 | curr = info; | |
2b144498 | 723 | |
26872090 | 724 | info->mm = vma->vm_mm; |
57683f72 | 725 | info->vaddr = offset_to_vaddr(vma, offset); |
26872090 | 726 | } |
2b144498 SD |
727 | mutex_unlock(&mapping->i_mmap_mutex); |
728 | ||
26872090 ON |
729 | if (!more) |
730 | goto out; | |
731 | ||
732 | prev = curr; | |
733 | while (curr) { | |
734 | mmput(curr->mm); | |
735 | curr = curr->next; | |
736 | } | |
7b2d81d4 | 737 | |
26872090 ON |
738 | do { |
739 | info = kmalloc(sizeof(struct map_info), GFP_KERNEL); | |
740 | if (!info) { | |
741 | curr = ERR_PTR(-ENOMEM); | |
742 | goto out; | |
743 | } | |
744 | info->next = prev; | |
745 | prev = info; | |
746 | } while (--more); | |
747 | ||
748 | goto again; | |
749 | out: | |
750 | while (prev) | |
751 | prev = free_map_info(prev); | |
752 | return curr; | |
2b144498 SD |
753 | } |
754 | ||
bdf8647c ON |
755 | static int |
756 | register_for_each_vma(struct uprobe *uprobe, struct uprobe_consumer *new) | |
2b144498 | 757 | { |
bdf8647c | 758 | bool is_register = !!new; |
26872090 ON |
759 | struct map_info *info; |
760 | int err = 0; | |
2b144498 | 761 | |
32cdba1e | 762 | percpu_down_write(&dup_mmap_sem); |
26872090 ON |
763 | info = build_map_info(uprobe->inode->i_mapping, |
764 | uprobe->offset, is_register); | |
32cdba1e ON |
765 | if (IS_ERR(info)) { |
766 | err = PTR_ERR(info); | |
767 | goto out; | |
768 | } | |
7b2d81d4 | 769 | |
26872090 ON |
770 | while (info) { |
771 | struct mm_struct *mm = info->mm; | |
772 | struct vm_area_struct *vma; | |
7b2d81d4 | 773 | |
076a365b | 774 | if (err && is_register) |
26872090 | 775 | goto free; |
7b2d81d4 | 776 | |
77fc4af1 | 777 | down_write(&mm->mmap_sem); |
f4d6dfe5 ON |
778 | vma = find_vma(mm, info->vaddr); |
779 | if (!vma || !valid_vma(vma, is_register) || | |
f281769e | 780 | file_inode(vma->vm_file) != uprobe->inode) |
26872090 ON |
781 | goto unlock; |
782 | ||
f4d6dfe5 ON |
783 | if (vma->vm_start > info->vaddr || |
784 | vaddr_to_offset(vma, info->vaddr) != uprobe->offset) | |
26872090 | 785 | goto unlock; |
2b144498 | 786 | |
806a98bd ON |
787 | if (is_register) { |
788 | /* consult only the "caller", new consumer. */ | |
bdf8647c | 789 | if (consumer_filter(new, |
8a7f2fa0 | 790 | UPROBE_FILTER_REGISTER, mm)) |
806a98bd ON |
791 | err = install_breakpoint(uprobe, mm, vma, info->vaddr); |
792 | } else if (test_bit(MMF_HAS_UPROBES, &mm->flags)) { | |
8a7f2fa0 ON |
793 | if (!filter_chain(uprobe, |
794 | UPROBE_FILTER_UNREGISTER, mm)) | |
806a98bd ON |
795 | err |= remove_breakpoint(uprobe, mm, info->vaddr); |
796 | } | |
78f74116 | 797 | |
26872090 ON |
798 | unlock: |
799 | up_write(&mm->mmap_sem); | |
800 | free: | |
801 | mmput(mm); | |
802 | info = free_map_info(info); | |
2b144498 | 803 | } |
32cdba1e ON |
804 | out: |
805 | percpu_up_write(&dup_mmap_sem); | |
26872090 | 806 | return err; |
2b144498 SD |
807 | } |
808 | ||
9a98e03c | 809 | static int __uprobe_register(struct uprobe *uprobe, struct uprobe_consumer *uc) |
2b144498 | 810 | { |
9a98e03c | 811 | consumer_add(uprobe, uc); |
bdf8647c | 812 | return register_for_each_vma(uprobe, uc); |
2b144498 SD |
813 | } |
814 | ||
04aab9b2 | 815 | static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc) |
2b144498 | 816 | { |
04aab9b2 ON |
817 | int err; |
818 | ||
819 | if (!consumer_del(uprobe, uc)) /* WARN? */ | |
820 | return; | |
2b144498 | 821 | |
bdf8647c | 822 | err = register_for_each_vma(uprobe, NULL); |
bb929284 ON |
823 | /* TODO : cant unregister? schedule a worker thread */ |
824 | if (!uprobe->consumers && !err) | |
825 | delete_uprobe(uprobe); | |
2b144498 SD |
826 | } |
827 | ||
828 | /* | |
7b2d81d4 | 829 | * uprobe_register - register a probe |
2b144498 SD |
830 | * @inode: the file in which the probe has to be placed. |
831 | * @offset: offset from the start of the file. | |
e3343e6a | 832 | * @uc: information on howto handle the probe.. |
2b144498 | 833 | * |
7b2d81d4 | 834 | * Apart from the access refcount, uprobe_register() takes a creation |
2b144498 SD |
835 | * refcount (thro alloc_uprobe) if and only if this @uprobe is getting |
836 | * inserted into the rbtree (i.e first consumer for a @inode:@offset | |
7b2d81d4 | 837 | * tuple). Creation refcount stops uprobe_unregister from freeing the |
2b144498 | 838 | * @uprobe even before the register operation is complete. Creation |
e3343e6a | 839 | * refcount is released when the last @uc for the @uprobe |
2b144498 SD |
840 | * unregisters. |
841 | * | |
842 | * Return errno if it cannot successully install probes | |
843 | * else return 0 (success) | |
844 | */ | |
e3343e6a | 845 | int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) |
2b144498 SD |
846 | { |
847 | struct uprobe *uprobe; | |
7b2d81d4 | 848 | int ret; |
2b144498 | 849 | |
ea024870 AA |
850 | /* Uprobe must have at least one set consumer */ |
851 | if (!uc->handler && !uc->ret_handler) | |
852 | return -EINVAL; | |
853 | ||
f0744af7 | 854 | /* Racy, just to catch the obvious mistakes */ |
2b144498 | 855 | if (offset > i_size_read(inode)) |
7b2d81d4 | 856 | return -EINVAL; |
2b144498 | 857 | |
66d06dff | 858 | retry: |
2b144498 | 859 | uprobe = alloc_uprobe(inode, offset); |
66d06dff ON |
860 | if (!uprobe) |
861 | return -ENOMEM; | |
862 | /* | |
863 | * We can race with uprobe_unregister()->delete_uprobe(). | |
864 | * Check uprobe_is_active() and retry if it is false. | |
865 | */ | |
866 | down_write(&uprobe->register_rwsem); | |
867 | ret = -EAGAIN; | |
868 | if (likely(uprobe_is_active(uprobe))) { | |
9a98e03c ON |
869 | ret = __uprobe_register(uprobe, uc); |
870 | if (ret) | |
04aab9b2 | 871 | __uprobe_unregister(uprobe, uc); |
2b144498 | 872 | } |
66d06dff ON |
873 | up_write(&uprobe->register_rwsem); |
874 | put_uprobe(uprobe); | |
2b144498 | 875 | |
66d06dff ON |
876 | if (unlikely(ret == -EAGAIN)) |
877 | goto retry; | |
2b144498 SD |
878 | return ret; |
879 | } | |
e8440c14 | 880 | EXPORT_SYMBOL_GPL(uprobe_register); |
2b144498 | 881 | |
bdf8647c ON |
882 | /* |
883 | * uprobe_apply - unregister a already registered probe. | |
884 | * @inode: the file in which the probe has to be removed. | |
885 | * @offset: offset from the start of the file. | |
886 | * @uc: consumer which wants to add more or remove some breakpoints | |
887 | * @add: add or remove the breakpoints | |
888 | */ | |
889 | int uprobe_apply(struct inode *inode, loff_t offset, | |
890 | struct uprobe_consumer *uc, bool add) | |
891 | { | |
892 | struct uprobe *uprobe; | |
893 | struct uprobe_consumer *con; | |
894 | int ret = -ENOENT; | |
895 | ||
896 | uprobe = find_uprobe(inode, offset); | |
897 | if (!uprobe) | |
898 | return ret; | |
899 | ||
900 | down_write(&uprobe->register_rwsem); | |
901 | for (con = uprobe->consumers; con && con != uc ; con = con->next) | |
902 | ; | |
903 | if (con) | |
904 | ret = register_for_each_vma(uprobe, add ? uc : NULL); | |
905 | up_write(&uprobe->register_rwsem); | |
906 | put_uprobe(uprobe); | |
907 | ||
908 | return ret; | |
909 | } | |
910 | ||
2b144498 | 911 | /* |
7b2d81d4 | 912 | * uprobe_unregister - unregister a already registered probe. |
2b144498 SD |
913 | * @inode: the file in which the probe has to be removed. |
914 | * @offset: offset from the start of the file. | |
e3343e6a | 915 | * @uc: identify which probe if multiple probes are colocated. |
2b144498 | 916 | */ |
e3343e6a | 917 | void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) |
2b144498 | 918 | { |
7b2d81d4 | 919 | struct uprobe *uprobe; |
2b144498 | 920 | |
2b144498 SD |
921 | uprobe = find_uprobe(inode, offset); |
922 | if (!uprobe) | |
923 | return; | |
924 | ||
e591c8d7 | 925 | down_write(&uprobe->register_rwsem); |
04aab9b2 | 926 | __uprobe_unregister(uprobe, uc); |
e591c8d7 | 927 | up_write(&uprobe->register_rwsem); |
c91368c4 | 928 | put_uprobe(uprobe); |
2b144498 | 929 | } |
e8440c14 | 930 | EXPORT_SYMBOL_GPL(uprobe_unregister); |
2b144498 | 931 | |
da1816b1 ON |
932 | static int unapply_uprobe(struct uprobe *uprobe, struct mm_struct *mm) |
933 | { | |
934 | struct vm_area_struct *vma; | |
935 | int err = 0; | |
936 | ||
937 | down_read(&mm->mmap_sem); | |
938 | for (vma = mm->mmap; vma; vma = vma->vm_next) { | |
939 | unsigned long vaddr; | |
940 | loff_t offset; | |
941 | ||
942 | if (!valid_vma(vma, false) || | |
f281769e | 943 | file_inode(vma->vm_file) != uprobe->inode) |
da1816b1 ON |
944 | continue; |
945 | ||
946 | offset = (loff_t)vma->vm_pgoff << PAGE_SHIFT; | |
947 | if (uprobe->offset < offset || | |
948 | uprobe->offset >= offset + vma->vm_end - vma->vm_start) | |
949 | continue; | |
950 | ||
951 | vaddr = offset_to_vaddr(vma, uprobe->offset); | |
952 | err |= remove_breakpoint(uprobe, mm, vaddr); | |
953 | } | |
954 | up_read(&mm->mmap_sem); | |
955 | ||
956 | return err; | |
957 | } | |
958 | ||
891c3970 ON |
959 | static struct rb_node * |
960 | find_node_in_range(struct inode *inode, loff_t min, loff_t max) | |
2b144498 | 961 | { |
2b144498 | 962 | struct rb_node *n = uprobes_tree.rb_node; |
2b144498 SD |
963 | |
964 | while (n) { | |
891c3970 | 965 | struct uprobe *u = rb_entry(n, struct uprobe, rb_node); |
2b144498 | 966 | |
891c3970 | 967 | if (inode < u->inode) { |
2b144498 | 968 | n = n->rb_left; |
891c3970 | 969 | } else if (inode > u->inode) { |
2b144498 | 970 | n = n->rb_right; |
891c3970 ON |
971 | } else { |
972 | if (max < u->offset) | |
973 | n = n->rb_left; | |
974 | else if (min > u->offset) | |
975 | n = n->rb_right; | |
976 | else | |
977 | break; | |
978 | } | |
2b144498 | 979 | } |
7b2d81d4 | 980 | |
891c3970 | 981 | return n; |
2b144498 SD |
982 | } |
983 | ||
984 | /* | |
891c3970 | 985 | * For a given range in vma, build a list of probes that need to be inserted. |
2b144498 | 986 | */ |
891c3970 ON |
987 | static void build_probe_list(struct inode *inode, |
988 | struct vm_area_struct *vma, | |
989 | unsigned long start, unsigned long end, | |
990 | struct list_head *head) | |
2b144498 | 991 | { |
891c3970 | 992 | loff_t min, max; |
891c3970 ON |
993 | struct rb_node *n, *t; |
994 | struct uprobe *u; | |
7b2d81d4 | 995 | |
891c3970 | 996 | INIT_LIST_HEAD(head); |
cb113b47 | 997 | min = vaddr_to_offset(vma, start); |
891c3970 | 998 | max = min + (end - start) - 1; |
2b144498 | 999 | |
6f47caa0 | 1000 | spin_lock(&uprobes_treelock); |
891c3970 ON |
1001 | n = find_node_in_range(inode, min, max); |
1002 | if (n) { | |
1003 | for (t = n; t; t = rb_prev(t)) { | |
1004 | u = rb_entry(t, struct uprobe, rb_node); | |
1005 | if (u->inode != inode || u->offset < min) | |
1006 | break; | |
1007 | list_add(&u->pending_list, head); | |
1008 | atomic_inc(&u->ref); | |
1009 | } | |
1010 | for (t = n; (t = rb_next(t)); ) { | |
1011 | u = rb_entry(t, struct uprobe, rb_node); | |
1012 | if (u->inode != inode || u->offset > max) | |
1013 | break; | |
1014 | list_add(&u->pending_list, head); | |
1015 | atomic_inc(&u->ref); | |
1016 | } | |
2b144498 | 1017 | } |
6f47caa0 | 1018 | spin_unlock(&uprobes_treelock); |
2b144498 SD |
1019 | } |
1020 | ||
1021 | /* | |
5e5be71a | 1022 | * Called from mmap_region/vma_adjust with mm->mmap_sem acquired. |
2b144498 | 1023 | * |
5e5be71a ON |
1024 | * Currently we ignore all errors and always return 0, the callers |
1025 | * can't handle the failure anyway. | |
2b144498 | 1026 | */ |
7b2d81d4 | 1027 | int uprobe_mmap(struct vm_area_struct *vma) |
2b144498 SD |
1028 | { |
1029 | struct list_head tmp_list; | |
665605a2 | 1030 | struct uprobe *uprobe, *u; |
2b144498 | 1031 | struct inode *inode; |
2b144498 | 1032 | |
441f1eb7 | 1033 | if (no_uprobe_events() || !valid_vma(vma, true)) |
7b2d81d4 | 1034 | return 0; |
2b144498 | 1035 | |
f281769e | 1036 | inode = file_inode(vma->vm_file); |
2b144498 | 1037 | if (!inode) |
7b2d81d4 | 1038 | return 0; |
2b144498 | 1039 | |
2b144498 | 1040 | mutex_lock(uprobes_mmap_hash(inode)); |
891c3970 | 1041 | build_probe_list(inode, vma, vma->vm_start, vma->vm_end, &tmp_list); |
806a98bd ON |
1042 | /* |
1043 | * We can race with uprobe_unregister(), this uprobe can be already | |
1044 | * removed. But in this case filter_chain() must return false, all | |
1045 | * consumers have gone away. | |
1046 | */ | |
665605a2 | 1047 | list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) { |
806a98bd | 1048 | if (!fatal_signal_pending(current) && |
8a7f2fa0 | 1049 | filter_chain(uprobe, UPROBE_FILTER_MMAP, vma->vm_mm)) { |
57683f72 | 1050 | unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset); |
5e5be71a | 1051 | install_breakpoint(uprobe, vma->vm_mm, vma, vaddr); |
2b144498 SD |
1052 | } |
1053 | put_uprobe(uprobe); | |
1054 | } | |
2b144498 SD |
1055 | mutex_unlock(uprobes_mmap_hash(inode)); |
1056 | ||
5e5be71a | 1057 | return 0; |
2b144498 SD |
1058 | } |
1059 | ||
9f68f672 ON |
1060 | static bool |
1061 | vma_has_uprobes(struct vm_area_struct *vma, unsigned long start, unsigned long end) | |
1062 | { | |
1063 | loff_t min, max; | |
1064 | struct inode *inode; | |
1065 | struct rb_node *n; | |
1066 | ||
f281769e | 1067 | inode = file_inode(vma->vm_file); |
9f68f672 ON |
1068 | |
1069 | min = vaddr_to_offset(vma, start); | |
1070 | max = min + (end - start) - 1; | |
1071 | ||
1072 | spin_lock(&uprobes_treelock); | |
1073 | n = find_node_in_range(inode, min, max); | |
1074 | spin_unlock(&uprobes_treelock); | |
1075 | ||
1076 | return !!n; | |
1077 | } | |
1078 | ||
682968e0 SD |
1079 | /* |
1080 | * Called in context of a munmap of a vma. | |
1081 | */ | |
cbc91f71 | 1082 | void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end) |
682968e0 | 1083 | { |
441f1eb7 | 1084 | if (no_uprobe_events() || !valid_vma(vma, false)) |
682968e0 SD |
1085 | return; |
1086 | ||
2fd611a9 ON |
1087 | if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */ |
1088 | return; | |
1089 | ||
9f68f672 ON |
1090 | if (!test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags) || |
1091 | test_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags)) | |
f8ac4ec9 ON |
1092 | return; |
1093 | ||
9f68f672 ON |
1094 | if (vma_has_uprobes(vma, start, end)) |
1095 | set_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags); | |
682968e0 SD |
1096 | } |
1097 | ||
d4b3b638 SD |
1098 | /* Slot allocation for XOL */ |
1099 | static int xol_add_vma(struct xol_area *area) | |
1100 | { | |
c8a82538 ON |
1101 | struct mm_struct *mm = current->mm; |
1102 | int ret = -EALREADY; | |
d4b3b638 SD |
1103 | |
1104 | down_write(&mm->mmap_sem); | |
1105 | if (mm->uprobes_state.xol_area) | |
1106 | goto fail; | |
1107 | ||
1108 | ret = -ENOMEM; | |
d4b3b638 SD |
1109 | /* Try to map as high as possible, this is only a hint. */ |
1110 | area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE, PAGE_SIZE, 0, 0); | |
1111 | if (area->vaddr & ~PAGE_MASK) { | |
1112 | ret = area->vaddr; | |
1113 | goto fail; | |
1114 | } | |
1115 | ||
1116 | ret = install_special_mapping(mm, area->vaddr, PAGE_SIZE, | |
1117 | VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO, &area->page); | |
1118 | if (ret) | |
1119 | goto fail; | |
1120 | ||
1121 | smp_wmb(); /* pairs with get_xol_area() */ | |
1122 | mm->uprobes_state.xol_area = area; | |
1123 | ret = 0; | |
c8a82538 | 1124 | fail: |
d4b3b638 | 1125 | up_write(&mm->mmap_sem); |
d4b3b638 SD |
1126 | |
1127 | return ret; | |
1128 | } | |
1129 | ||
d4b3b638 | 1130 | /* |
9b545df8 ON |
1131 | * get_xol_area - Allocate process's xol_area if necessary. |
1132 | * This area will be used for storing instructions for execution out of line. | |
d4b3b638 SD |
1133 | * |
1134 | * Returns the allocated area or NULL. | |
1135 | */ | |
9b545df8 | 1136 | static struct xol_area *get_xol_area(void) |
d4b3b638 | 1137 | { |
9b545df8 | 1138 | struct mm_struct *mm = current->mm; |
d4b3b638 | 1139 | struct xol_area *area; |
e78aebfd | 1140 | uprobe_opcode_t insn = UPROBE_SWBP_INSN; |
d4b3b638 | 1141 | |
9b545df8 ON |
1142 | area = mm->uprobes_state.xol_area; |
1143 | if (area) | |
1144 | goto ret; | |
1145 | ||
d4b3b638 SD |
1146 | area = kzalloc(sizeof(*area), GFP_KERNEL); |
1147 | if (unlikely(!area)) | |
c8a82538 | 1148 | goto out; |
d4b3b638 SD |
1149 | |
1150 | area->bitmap = kzalloc(BITS_TO_LONGS(UINSNS_PER_PAGE) * sizeof(long), GFP_KERNEL); | |
d4b3b638 | 1151 | if (!area->bitmap) |
c8a82538 ON |
1152 | goto free_area; |
1153 | ||
1154 | area->page = alloc_page(GFP_HIGHUSER); | |
1155 | if (!area->page) | |
1156 | goto free_bitmap; | |
d4b3b638 | 1157 | |
e78aebfd AA |
1158 | /* allocate first slot of task's xol_area for the return probes */ |
1159 | set_bit(0, area->bitmap); | |
1160 | copy_to_page(area->page, 0, &insn, UPROBE_SWBP_INSN_SIZE); | |
1161 | atomic_set(&area->slot_count, 1); | |
d4b3b638 | 1162 | init_waitqueue_head(&area->wq); |
e78aebfd | 1163 | |
d4b3b638 SD |
1164 | if (!xol_add_vma(area)) |
1165 | return area; | |
1166 | ||
c8a82538 ON |
1167 | __free_page(area->page); |
1168 | free_bitmap: | |
d4b3b638 | 1169 | kfree(area->bitmap); |
c8a82538 | 1170 | free_area: |
d4b3b638 | 1171 | kfree(area); |
c8a82538 | 1172 | out: |
9b545df8 ON |
1173 | area = mm->uprobes_state.xol_area; |
1174 | ret: | |
1175 | smp_read_barrier_depends(); /* pairs with wmb in xol_add_vma() */ | |
1176 | return area; | |
d4b3b638 SD |
1177 | } |
1178 | ||
1179 | /* | |
1180 | * uprobe_clear_state - Free the area allocated for slots. | |
1181 | */ | |
1182 | void uprobe_clear_state(struct mm_struct *mm) | |
1183 | { | |
1184 | struct xol_area *area = mm->uprobes_state.xol_area; | |
1185 | ||
1186 | if (!area) | |
1187 | return; | |
1188 | ||
1189 | put_page(area->page); | |
1190 | kfree(area->bitmap); | |
1191 | kfree(area); | |
1192 | } | |
1193 | ||
32cdba1e ON |
1194 | void uprobe_start_dup_mmap(void) |
1195 | { | |
1196 | percpu_down_read(&dup_mmap_sem); | |
1197 | } | |
1198 | ||
1199 | void uprobe_end_dup_mmap(void) | |
1200 | { | |
1201 | percpu_up_read(&dup_mmap_sem); | |
1202 | } | |
1203 | ||
f8ac4ec9 ON |
1204 | void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm) |
1205 | { | |
61559a81 ON |
1206 | newmm->uprobes_state.xol_area = NULL; |
1207 | ||
9f68f672 | 1208 | if (test_bit(MMF_HAS_UPROBES, &oldmm->flags)) { |
f8ac4ec9 | 1209 | set_bit(MMF_HAS_UPROBES, &newmm->flags); |
9f68f672 ON |
1210 | /* unconditionally, dup_mmap() skips VM_DONTCOPY vmas */ |
1211 | set_bit(MMF_RECALC_UPROBES, &newmm->flags); | |
1212 | } | |
f8ac4ec9 ON |
1213 | } |
1214 | ||
d4b3b638 SD |
1215 | /* |
1216 | * - search for a free slot. | |
1217 | */ | |
1218 | static unsigned long xol_take_insn_slot(struct xol_area *area) | |
1219 | { | |
1220 | unsigned long slot_addr; | |
1221 | int slot_nr; | |
1222 | ||
1223 | do { | |
1224 | slot_nr = find_first_zero_bit(area->bitmap, UINSNS_PER_PAGE); | |
1225 | if (slot_nr < UINSNS_PER_PAGE) { | |
1226 | if (!test_and_set_bit(slot_nr, area->bitmap)) | |
1227 | break; | |
1228 | ||
1229 | slot_nr = UINSNS_PER_PAGE; | |
1230 | continue; | |
1231 | } | |
1232 | wait_event(area->wq, (atomic_read(&area->slot_count) < UINSNS_PER_PAGE)); | |
1233 | } while (slot_nr >= UINSNS_PER_PAGE); | |
1234 | ||
1235 | slot_addr = area->vaddr + (slot_nr * UPROBE_XOL_SLOT_BYTES); | |
1236 | atomic_inc(&area->slot_count); | |
1237 | ||
1238 | return slot_addr; | |
1239 | } | |
1240 | ||
1241 | /* | |
a6cb3f6d | 1242 | * xol_get_insn_slot - allocate a slot for xol. |
d4b3b638 SD |
1243 | * Returns the allocated slot address or 0. |
1244 | */ | |
a6cb3f6d | 1245 | static unsigned long xol_get_insn_slot(struct uprobe *uprobe) |
d4b3b638 SD |
1246 | { |
1247 | struct xol_area *area; | |
a6cb3f6d | 1248 | unsigned long xol_vaddr; |
d4b3b638 | 1249 | |
9b545df8 ON |
1250 | area = get_xol_area(); |
1251 | if (!area) | |
1252 | return 0; | |
d4b3b638 | 1253 | |
a6cb3f6d ON |
1254 | xol_vaddr = xol_take_insn_slot(area); |
1255 | if (unlikely(!xol_vaddr)) | |
d4b3b638 SD |
1256 | return 0; |
1257 | ||
a6cb3f6d | 1258 | /* Initialize the slot */ |
5669ccee | 1259 | copy_to_page(area->page, xol_vaddr, uprobe->arch.insn, MAX_UINSN_BYTES); |
65b6ecc0 RV |
1260 | /* |
1261 | * We probably need flush_icache_user_range() but it needs vma. | |
1262 | * This should work on supported architectures too. | |
1263 | */ | |
1264 | flush_dcache_page(area->page); | |
d4b3b638 | 1265 | |
a6cb3f6d | 1266 | return xol_vaddr; |
d4b3b638 SD |
1267 | } |
1268 | ||
1269 | /* | |
1270 | * xol_free_insn_slot - If slot was earlier allocated by | |
1271 | * @xol_get_insn_slot(), make the slot available for | |
1272 | * subsequent requests. | |
1273 | */ | |
1274 | static void xol_free_insn_slot(struct task_struct *tsk) | |
1275 | { | |
1276 | struct xol_area *area; | |
1277 | unsigned long vma_end; | |
1278 | unsigned long slot_addr; | |
1279 | ||
1280 | if (!tsk->mm || !tsk->mm->uprobes_state.xol_area || !tsk->utask) | |
1281 | return; | |
1282 | ||
1283 | slot_addr = tsk->utask->xol_vaddr; | |
af4355e9 | 1284 | if (unlikely(!slot_addr)) |
d4b3b638 SD |
1285 | return; |
1286 | ||
1287 | area = tsk->mm->uprobes_state.xol_area; | |
1288 | vma_end = area->vaddr + PAGE_SIZE; | |
1289 | if (area->vaddr <= slot_addr && slot_addr < vma_end) { | |
1290 | unsigned long offset; | |
1291 | int slot_nr; | |
1292 | ||
1293 | offset = slot_addr - area->vaddr; | |
1294 | slot_nr = offset / UPROBE_XOL_SLOT_BYTES; | |
1295 | if (slot_nr >= UINSNS_PER_PAGE) | |
1296 | return; | |
1297 | ||
1298 | clear_bit(slot_nr, area->bitmap); | |
1299 | atomic_dec(&area->slot_count); | |
1300 | if (waitqueue_active(&area->wq)) | |
1301 | wake_up(&area->wq); | |
1302 | ||
1303 | tsk->utask->xol_vaddr = 0; | |
1304 | } | |
1305 | } | |
1306 | ||
0326f5a9 SD |
1307 | /** |
1308 | * uprobe_get_swbp_addr - compute address of swbp given post-swbp regs | |
1309 | * @regs: Reflects the saved state of the task after it has hit a breakpoint | |
1310 | * instruction. | |
1311 | * Return the address of the breakpoint instruction. | |
1312 | */ | |
1313 | unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs) | |
1314 | { | |
1315 | return instruction_pointer(regs) - UPROBE_SWBP_INSN_SIZE; | |
1316 | } | |
1317 | ||
1318 | /* | |
1319 | * Called with no locks held. | |
1320 | * Called in context of a exiting or a exec-ing thread. | |
1321 | */ | |
1322 | void uprobe_free_utask(struct task_struct *t) | |
1323 | { | |
1324 | struct uprobe_task *utask = t->utask; | |
0dfd0eb8 | 1325 | struct return_instance *ri, *tmp; |
0326f5a9 | 1326 | |
0326f5a9 SD |
1327 | if (!utask) |
1328 | return; | |
1329 | ||
1330 | if (utask->active_uprobe) | |
1331 | put_uprobe(utask->active_uprobe); | |
1332 | ||
0dfd0eb8 AA |
1333 | ri = utask->return_instances; |
1334 | while (ri) { | |
1335 | tmp = ri; | |
1336 | ri = ri->next; | |
1337 | ||
1338 | put_uprobe(tmp->uprobe); | |
1339 | kfree(tmp); | |
1340 | } | |
1341 | ||
d4b3b638 | 1342 | xol_free_insn_slot(t); |
0326f5a9 SD |
1343 | kfree(utask); |
1344 | t->utask = NULL; | |
1345 | } | |
1346 | ||
1347 | /* | |
1348 | * Called in context of a new clone/fork from copy_process. | |
1349 | */ | |
1350 | void uprobe_copy_process(struct task_struct *t) | |
1351 | { | |
1352 | t->utask = NULL; | |
0326f5a9 SD |
1353 | } |
1354 | ||
1355 | /* | |
5a2df662 ON |
1356 | * Allocate a uprobe_task object for the task if if necessary. |
1357 | * Called when the thread hits a breakpoint. | |
0326f5a9 SD |
1358 | * |
1359 | * Returns: | |
1360 | * - pointer to new uprobe_task on success | |
1361 | * - NULL otherwise | |
1362 | */ | |
5a2df662 | 1363 | static struct uprobe_task *get_utask(void) |
0326f5a9 | 1364 | { |
5a2df662 ON |
1365 | if (!current->utask) |
1366 | current->utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL); | |
1367 | return current->utask; | |
0326f5a9 SD |
1368 | } |
1369 | ||
e78aebfd AA |
1370 | /* |
1371 | * Current area->vaddr notion assume the trampoline address is always | |
1372 | * equal area->vaddr. | |
1373 | * | |
1374 | * Returns -1 in case the xol_area is not allocated. | |
1375 | */ | |
1376 | static unsigned long get_trampoline_vaddr(void) | |
1377 | { | |
1378 | struct xol_area *area; | |
1379 | unsigned long trampoline_vaddr = -1; | |
1380 | ||
1381 | area = current->mm->uprobes_state.xol_area; | |
1382 | smp_read_barrier_depends(); | |
1383 | if (area) | |
1384 | trampoline_vaddr = area->vaddr; | |
1385 | ||
1386 | return trampoline_vaddr; | |
1387 | } | |
1388 | ||
0dfd0eb8 AA |
1389 | static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs) |
1390 | { | |
1391 | struct return_instance *ri; | |
1392 | struct uprobe_task *utask; | |
1393 | unsigned long orig_ret_vaddr, trampoline_vaddr; | |
1394 | bool chained = false; | |
1395 | ||
1396 | if (!get_xol_area()) | |
1397 | return; | |
1398 | ||
1399 | utask = get_utask(); | |
1400 | if (!utask) | |
1401 | return; | |
1402 | ||
ded49c55 AA |
1403 | if (utask->depth >= MAX_URETPROBE_DEPTH) { |
1404 | printk_ratelimited(KERN_INFO "uprobe: omit uretprobe due to" | |
1405 | " nestedness limit pid/tgid=%d/%d\n", | |
1406 | current->pid, current->tgid); | |
1407 | return; | |
1408 | } | |
1409 | ||
0dfd0eb8 AA |
1410 | ri = kzalloc(sizeof(struct return_instance), GFP_KERNEL); |
1411 | if (!ri) | |
1412 | goto fail; | |
1413 | ||
1414 | trampoline_vaddr = get_trampoline_vaddr(); | |
1415 | orig_ret_vaddr = arch_uretprobe_hijack_return_addr(trampoline_vaddr, regs); | |
1416 | if (orig_ret_vaddr == -1) | |
1417 | goto fail; | |
1418 | ||
1419 | /* | |
1420 | * We don't want to keep trampoline address in stack, rather keep the | |
1421 | * original return address of first caller thru all the consequent | |
1422 | * instances. This also makes breakpoint unwrapping easier. | |
1423 | */ | |
1424 | if (orig_ret_vaddr == trampoline_vaddr) { | |
1425 | if (!utask->return_instances) { | |
1426 | /* | |
1427 | * This situation is not possible. Likely we have an | |
1428 | * attack from user-space. | |
1429 | */ | |
1430 | pr_warn("uprobe: unable to set uretprobe pid/tgid=%d/%d\n", | |
1431 | current->pid, current->tgid); | |
1432 | goto fail; | |
1433 | } | |
1434 | ||
1435 | chained = true; | |
1436 | orig_ret_vaddr = utask->return_instances->orig_ret_vaddr; | |
1437 | } | |
1438 | ||
1439 | atomic_inc(&uprobe->ref); | |
1440 | ri->uprobe = uprobe; | |
1441 | ri->func = instruction_pointer(regs); | |
1442 | ri->orig_ret_vaddr = orig_ret_vaddr; | |
1443 | ri->chained = chained; | |
1444 | ||
ded49c55 AA |
1445 | utask->depth++; |
1446 | ||
0dfd0eb8 AA |
1447 | /* add instance to the stack */ |
1448 | ri->next = utask->return_instances; | |
1449 | utask->return_instances = ri; | |
1450 | ||
1451 | return; | |
1452 | ||
1453 | fail: | |
1454 | kfree(ri); | |
1455 | } | |
1456 | ||
0326f5a9 SD |
1457 | /* Prepare to single-step probed instruction out of line. */ |
1458 | static int | |
a6cb3f6d | 1459 | pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long bp_vaddr) |
0326f5a9 | 1460 | { |
a6cb3f6d ON |
1461 | struct uprobe_task *utask; |
1462 | unsigned long xol_vaddr; | |
aba51024 | 1463 | int err; |
a6cb3f6d | 1464 | |
608e7427 ON |
1465 | utask = get_utask(); |
1466 | if (!utask) | |
1467 | return -ENOMEM; | |
a6cb3f6d ON |
1468 | |
1469 | xol_vaddr = xol_get_insn_slot(uprobe); | |
1470 | if (!xol_vaddr) | |
1471 | return -ENOMEM; | |
1472 | ||
1473 | utask->xol_vaddr = xol_vaddr; | |
1474 | utask->vaddr = bp_vaddr; | |
d4b3b638 | 1475 | |
aba51024 ON |
1476 | err = arch_uprobe_pre_xol(&uprobe->arch, regs); |
1477 | if (unlikely(err)) { | |
1478 | xol_free_insn_slot(current); | |
1479 | return err; | |
1480 | } | |
1481 | ||
608e7427 ON |
1482 | utask->active_uprobe = uprobe; |
1483 | utask->state = UTASK_SSTEP; | |
aba51024 | 1484 | return 0; |
0326f5a9 SD |
1485 | } |
1486 | ||
1487 | /* | |
1488 | * If we are singlestepping, then ensure this thread is not connected to | |
1489 | * non-fatal signals until completion of singlestep. When xol insn itself | |
1490 | * triggers the signal, restart the original insn even if the task is | |
1491 | * already SIGKILL'ed (since coredump should report the correct ip). This | |
1492 | * is even more important if the task has a handler for SIGSEGV/etc, The | |
1493 | * _same_ instruction should be repeated again after return from the signal | |
1494 | * handler, and SSTEP can never finish in this case. | |
1495 | */ | |
1496 | bool uprobe_deny_signal(void) | |
1497 | { | |
1498 | struct task_struct *t = current; | |
1499 | struct uprobe_task *utask = t->utask; | |
1500 | ||
1501 | if (likely(!utask || !utask->active_uprobe)) | |
1502 | return false; | |
1503 | ||
1504 | WARN_ON_ONCE(utask->state != UTASK_SSTEP); | |
1505 | ||
1506 | if (signal_pending(t)) { | |
1507 | spin_lock_irq(&t->sighand->siglock); | |
1508 | clear_tsk_thread_flag(t, TIF_SIGPENDING); | |
1509 | spin_unlock_irq(&t->sighand->siglock); | |
1510 | ||
1511 | if (__fatal_signal_pending(t) || arch_uprobe_xol_was_trapped(t)) { | |
1512 | utask->state = UTASK_SSTEP_TRAPPED; | |
1513 | set_tsk_thread_flag(t, TIF_UPROBE); | |
1514 | set_tsk_thread_flag(t, TIF_NOTIFY_RESUME); | |
1515 | } | |
1516 | } | |
1517 | ||
1518 | return true; | |
1519 | } | |
1520 | ||
1521 | /* | |
1522 | * Avoid singlestepping the original instruction if the original instruction | |
1523 | * is a NOP or can be emulated. | |
1524 | */ | |
1525 | static bool can_skip_sstep(struct uprobe *uprobe, struct pt_regs *regs) | |
1526 | { | |
71434f2f | 1527 | if (test_bit(UPROBE_SKIP_SSTEP, &uprobe->flags)) { |
0578a970 ON |
1528 | if (arch_uprobe_skip_sstep(&uprobe->arch, regs)) |
1529 | return true; | |
71434f2f | 1530 | clear_bit(UPROBE_SKIP_SSTEP, &uprobe->flags); |
0578a970 | 1531 | } |
0326f5a9 SD |
1532 | return false; |
1533 | } | |
1534 | ||
499a4f3e ON |
1535 | static void mmf_recalc_uprobes(struct mm_struct *mm) |
1536 | { | |
1537 | struct vm_area_struct *vma; | |
1538 | ||
1539 | for (vma = mm->mmap; vma; vma = vma->vm_next) { | |
1540 | if (!valid_vma(vma, false)) | |
1541 | continue; | |
1542 | /* | |
1543 | * This is not strictly accurate, we can race with | |
1544 | * uprobe_unregister() and see the already removed | |
1545 | * uprobe if delete_uprobe() was not yet called. | |
63633cbf | 1546 | * Or this uprobe can be filtered out. |
499a4f3e ON |
1547 | */ |
1548 | if (vma_has_uprobes(vma, vma->vm_start, vma->vm_end)) | |
1549 | return; | |
1550 | } | |
1551 | ||
1552 | clear_bit(MMF_HAS_UPROBES, &mm->flags); | |
1553 | } | |
1554 | ||
0908ad6e | 1555 | static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr) |
ec75fba9 ON |
1556 | { |
1557 | struct page *page; | |
1558 | uprobe_opcode_t opcode; | |
1559 | int result; | |
1560 | ||
1561 | pagefault_disable(); | |
1562 | result = __copy_from_user_inatomic(&opcode, (void __user*)vaddr, | |
1563 | sizeof(opcode)); | |
1564 | pagefault_enable(); | |
1565 | ||
1566 | if (likely(result == 0)) | |
1567 | goto out; | |
1568 | ||
1569 | result = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL); | |
1570 | if (result < 0) | |
1571 | return result; | |
1572 | ||
ab0d805c | 1573 | copy_from_page(page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE); |
ec75fba9 ON |
1574 | put_page(page); |
1575 | out: | |
0908ad6e AM |
1576 | /* This needs to return true for any variant of the trap insn */ |
1577 | return is_trap_insn(&opcode); | |
ec75fba9 ON |
1578 | } |
1579 | ||
d790d346 | 1580 | static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp) |
0326f5a9 | 1581 | { |
3a9ea052 ON |
1582 | struct mm_struct *mm = current->mm; |
1583 | struct uprobe *uprobe = NULL; | |
0326f5a9 | 1584 | struct vm_area_struct *vma; |
0326f5a9 | 1585 | |
0326f5a9 SD |
1586 | down_read(&mm->mmap_sem); |
1587 | vma = find_vma(mm, bp_vaddr); | |
3a9ea052 ON |
1588 | if (vma && vma->vm_start <= bp_vaddr) { |
1589 | if (valid_vma(vma, false)) { | |
f281769e | 1590 | struct inode *inode = file_inode(vma->vm_file); |
cb113b47 | 1591 | loff_t offset = vaddr_to_offset(vma, bp_vaddr); |
0326f5a9 | 1592 | |
3a9ea052 ON |
1593 | uprobe = find_uprobe(inode, offset); |
1594 | } | |
d790d346 ON |
1595 | |
1596 | if (!uprobe) | |
0908ad6e | 1597 | *is_swbp = is_trap_at_addr(mm, bp_vaddr); |
d790d346 ON |
1598 | } else { |
1599 | *is_swbp = -EFAULT; | |
0326f5a9 | 1600 | } |
499a4f3e ON |
1601 | |
1602 | if (!uprobe && test_and_clear_bit(MMF_RECALC_UPROBES, &mm->flags)) | |
1603 | mmf_recalc_uprobes(mm); | |
0326f5a9 SD |
1604 | up_read(&mm->mmap_sem); |
1605 | ||
3a9ea052 ON |
1606 | return uprobe; |
1607 | } | |
1608 | ||
da1816b1 ON |
1609 | static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs) |
1610 | { | |
1611 | struct uprobe_consumer *uc; | |
1612 | int remove = UPROBE_HANDLER_REMOVE; | |
0dfd0eb8 | 1613 | bool need_prep = false; /* prepare return uprobe, when needed */ |
da1816b1 ON |
1614 | |
1615 | down_read(&uprobe->register_rwsem); | |
1616 | for (uc = uprobe->consumers; uc; uc = uc->next) { | |
ea024870 | 1617 | int rc = 0; |
da1816b1 | 1618 | |
ea024870 AA |
1619 | if (uc->handler) { |
1620 | rc = uc->handler(uc, regs); | |
1621 | WARN(rc & ~UPROBE_HANDLER_MASK, | |
1622 | "bad rc=0x%x from %pf()\n", rc, uc->handler); | |
1623 | } | |
0dfd0eb8 AA |
1624 | |
1625 | if (uc->ret_handler) | |
1626 | need_prep = true; | |
1627 | ||
da1816b1 ON |
1628 | remove &= rc; |
1629 | } | |
1630 | ||
0dfd0eb8 AA |
1631 | if (need_prep && !remove) |
1632 | prepare_uretprobe(uprobe, regs); /* put bp at return */ | |
1633 | ||
da1816b1 ON |
1634 | if (remove && uprobe->consumers) { |
1635 | WARN_ON(!uprobe_is_active(uprobe)); | |
1636 | unapply_uprobe(uprobe, current->mm); | |
1637 | } | |
1638 | up_read(&uprobe->register_rwsem); | |
1639 | } | |
1640 | ||
fec8898d AA |
1641 | static void |
1642 | handle_uretprobe_chain(struct return_instance *ri, struct pt_regs *regs) | |
1643 | { | |
1644 | struct uprobe *uprobe = ri->uprobe; | |
1645 | struct uprobe_consumer *uc; | |
1646 | ||
1647 | down_read(&uprobe->register_rwsem); | |
1648 | for (uc = uprobe->consumers; uc; uc = uc->next) { | |
1649 | if (uc->ret_handler) | |
1650 | uc->ret_handler(uc, ri->func, regs); | |
1651 | } | |
1652 | up_read(&uprobe->register_rwsem); | |
1653 | } | |
1654 | ||
1655 | static bool handle_trampoline(struct pt_regs *regs) | |
1656 | { | |
1657 | struct uprobe_task *utask; | |
1658 | struct return_instance *ri, *tmp; | |
1659 | bool chained; | |
1660 | ||
1661 | utask = current->utask; | |
1662 | if (!utask) | |
1663 | return false; | |
1664 | ||
1665 | ri = utask->return_instances; | |
1666 | if (!ri) | |
1667 | return false; | |
1668 | ||
1669 | /* | |
1670 | * TODO: we should throw out return_instance's invalidated by | |
1671 | * longjmp(), currently we assume that the probed function always | |
1672 | * returns. | |
1673 | */ | |
1674 | instruction_pointer_set(regs, ri->orig_ret_vaddr); | |
1675 | ||
1676 | for (;;) { | |
1677 | handle_uretprobe_chain(ri, regs); | |
1678 | ||
1679 | chained = ri->chained; | |
1680 | put_uprobe(ri->uprobe); | |
1681 | ||
1682 | tmp = ri; | |
1683 | ri = ri->next; | |
1684 | kfree(tmp); | |
878b5a6e | 1685 | utask->depth--; |
fec8898d AA |
1686 | |
1687 | if (!chained) | |
1688 | break; | |
fec8898d AA |
1689 | BUG_ON(!ri); |
1690 | } | |
1691 | ||
1692 | utask->return_instances = ri; | |
1693 | ||
1694 | return true; | |
1695 | } | |
1696 | ||
3a9ea052 ON |
1697 | /* |
1698 | * Run handler and ask thread to singlestep. | |
1699 | * Ensure all non-fatal signals cannot interrupt thread while it singlesteps. | |
1700 | */ | |
1701 | static void handle_swbp(struct pt_regs *regs) | |
1702 | { | |
3a9ea052 ON |
1703 | struct uprobe *uprobe; |
1704 | unsigned long bp_vaddr; | |
56bb4cf6 | 1705 | int uninitialized_var(is_swbp); |
3a9ea052 ON |
1706 | |
1707 | bp_vaddr = uprobe_get_swbp_addr(regs); | |
fec8898d AA |
1708 | if (bp_vaddr == get_trampoline_vaddr()) { |
1709 | if (handle_trampoline(regs)) | |
1710 | return; | |
3a9ea052 | 1711 | |
fec8898d AA |
1712 | pr_warn("uprobe: unable to handle uretprobe pid/tgid=%d/%d\n", |
1713 | current->pid, current->tgid); | |
1714 | } | |
1715 | ||
1716 | uprobe = find_active_uprobe(bp_vaddr, &is_swbp); | |
0326f5a9 | 1717 | if (!uprobe) { |
56bb4cf6 ON |
1718 | if (is_swbp > 0) { |
1719 | /* No matching uprobe; signal SIGTRAP. */ | |
1720 | send_sig(SIGTRAP, current, 0); | |
1721 | } else { | |
1722 | /* | |
1723 | * Either we raced with uprobe_unregister() or we can't | |
1724 | * access this memory. The latter is only possible if | |
1725 | * another thread plays with our ->mm. In both cases | |
1726 | * we can simply restart. If this vma was unmapped we | |
1727 | * can pretend this insn was not executed yet and get | |
1728 | * the (correct) SIGSEGV after restart. | |
1729 | */ | |
1730 | instruction_pointer_set(regs, bp_vaddr); | |
1731 | } | |
0326f5a9 SD |
1732 | return; |
1733 | } | |
74e59dfc ON |
1734 | |
1735 | /* change it in advance for ->handler() and restart */ | |
1736 | instruction_pointer_set(regs, bp_vaddr); | |
1737 | ||
142b18dd ON |
1738 | /* |
1739 | * TODO: move copy_insn/etc into _register and remove this hack. | |
1740 | * After we hit the bp, _unregister + _register can install the | |
1741 | * new and not-yet-analyzed uprobe at the same address, restart. | |
1742 | */ | |
1743 | smp_rmb(); /* pairs with wmb() in install_breakpoint() */ | |
71434f2f | 1744 | if (unlikely(!test_bit(UPROBE_COPY_INSN, &uprobe->flags))) |
74e59dfc | 1745 | goto out; |
0326f5a9 | 1746 | |
0326f5a9 | 1747 | handler_chain(uprobe, regs); |
0578a970 ON |
1748 | if (can_skip_sstep(uprobe, regs)) |
1749 | goto out; | |
0326f5a9 | 1750 | |
608e7427 | 1751 | if (!pre_ssout(uprobe, regs, bp_vaddr)) |
0326f5a9 | 1752 | return; |
0326f5a9 | 1753 | |
74e59dfc | 1754 | /* can_skip_sstep() succeeded, or restart if can't singlestep */ |
0578a970 | 1755 | out: |
8bd87445 | 1756 | put_uprobe(uprobe); |
0326f5a9 SD |
1757 | } |
1758 | ||
1759 | /* | |
1760 | * Perform required fix-ups and disable singlestep. | |
1761 | * Allow pending signals to take effect. | |
1762 | */ | |
1763 | static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs) | |
1764 | { | |
1765 | struct uprobe *uprobe; | |
1766 | ||
1767 | uprobe = utask->active_uprobe; | |
1768 | if (utask->state == UTASK_SSTEP_ACK) | |
1769 | arch_uprobe_post_xol(&uprobe->arch, regs); | |
1770 | else if (utask->state == UTASK_SSTEP_TRAPPED) | |
1771 | arch_uprobe_abort_xol(&uprobe->arch, regs); | |
1772 | else | |
1773 | WARN_ON_ONCE(1); | |
1774 | ||
1775 | put_uprobe(uprobe); | |
1776 | utask->active_uprobe = NULL; | |
1777 | utask->state = UTASK_RUNNING; | |
d4b3b638 | 1778 | xol_free_insn_slot(current); |
0326f5a9 SD |
1779 | |
1780 | spin_lock_irq(¤t->sighand->siglock); | |
1781 | recalc_sigpending(); /* see uprobe_deny_signal() */ | |
1782 | spin_unlock_irq(¤t->sighand->siglock); | |
1783 | } | |
1784 | ||
1785 | /* | |
1b08e907 ON |
1786 | * On breakpoint hit, breakpoint notifier sets the TIF_UPROBE flag and |
1787 | * allows the thread to return from interrupt. After that handle_swbp() | |
1788 | * sets utask->active_uprobe. | |
0326f5a9 | 1789 | * |
1b08e907 ON |
1790 | * On singlestep exception, singlestep notifier sets the TIF_UPROBE flag |
1791 | * and allows the thread to return from interrupt. | |
0326f5a9 SD |
1792 | * |
1793 | * While returning to userspace, thread notices the TIF_UPROBE flag and calls | |
1794 | * uprobe_notify_resume(). | |
1795 | */ | |
1796 | void uprobe_notify_resume(struct pt_regs *regs) | |
1797 | { | |
1798 | struct uprobe_task *utask; | |
1799 | ||
db023ea5 ON |
1800 | clear_thread_flag(TIF_UPROBE); |
1801 | ||
0326f5a9 | 1802 | utask = current->utask; |
1b08e907 | 1803 | if (utask && utask->active_uprobe) |
0326f5a9 | 1804 | handle_singlestep(utask, regs); |
1b08e907 ON |
1805 | else |
1806 | handle_swbp(regs); | |
0326f5a9 SD |
1807 | } |
1808 | ||
1809 | /* | |
1810 | * uprobe_pre_sstep_notifier gets called from interrupt context as part of | |
1811 | * notifier mechanism. Set TIF_UPROBE flag and indicate breakpoint hit. | |
1812 | */ | |
1813 | int uprobe_pre_sstep_notifier(struct pt_regs *regs) | |
1814 | { | |
0dfd0eb8 AA |
1815 | if (!current->mm) |
1816 | return 0; | |
1817 | ||
1818 | if (!test_bit(MMF_HAS_UPROBES, ¤t->mm->flags) && | |
1819 | (!current->utask || !current->utask->return_instances)) | |
0326f5a9 SD |
1820 | return 0; |
1821 | ||
0326f5a9 | 1822 | set_thread_flag(TIF_UPROBE); |
0326f5a9 SD |
1823 | return 1; |
1824 | } | |
1825 | ||
1826 | /* | |
1827 | * uprobe_post_sstep_notifier gets called in interrupt context as part of notifier | |
1828 | * mechanism. Set TIF_UPROBE flag and indicate completion of singlestep. | |
1829 | */ | |
1830 | int uprobe_post_sstep_notifier(struct pt_regs *regs) | |
1831 | { | |
1832 | struct uprobe_task *utask = current->utask; | |
1833 | ||
1834 | if (!current->mm || !utask || !utask->active_uprobe) | |
1835 | /* task is currently not uprobed */ | |
1836 | return 0; | |
1837 | ||
1838 | utask->state = UTASK_SSTEP_ACK; | |
1839 | set_thread_flag(TIF_UPROBE); | |
1840 | return 1; | |
1841 | } | |
1842 | ||
1843 | static struct notifier_block uprobe_exception_nb = { | |
1844 | .notifier_call = arch_uprobe_exception_notify, | |
1845 | .priority = INT_MAX-1, /* notified after kprobes, kgdb */ | |
1846 | }; | |
1847 | ||
2b144498 SD |
1848 | static int __init init_uprobes(void) |
1849 | { | |
1850 | int i; | |
1851 | ||
66d06dff | 1852 | for (i = 0; i < UPROBES_HASH_SZ; i++) |
2b144498 | 1853 | mutex_init(&uprobes_mmap_mutex[i]); |
0326f5a9 | 1854 | |
32cdba1e ON |
1855 | if (percpu_init_rwsem(&dup_mmap_sem)) |
1856 | return -ENOMEM; | |
1857 | ||
0326f5a9 | 1858 | return register_die_notifier(&uprobe_exception_nb); |
2b144498 | 1859 | } |
0326f5a9 | 1860 | module_init(init_uprobes); |
2b144498 SD |
1861 | |
1862 | static void __exit exit_uprobes(void) | |
1863 | { | |
1864 | } | |
2b144498 | 1865 | module_exit(exit_uprobes); |