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2b144498 | 1 | /* |
7b2d81d4 | 2 | * User-space Probes (UProbes) |
2b144498 SD |
3 | * |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License as published by | |
6 | * the Free Software Foundation; either version 2 of the License, or | |
7 | * (at your option) any later version. | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | * GNU General Public License for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License | |
15 | * along with this program; if not, write to the Free Software | |
16 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
17 | * | |
35aa621b | 18 | * Copyright (C) IBM Corporation, 2008-2012 |
2b144498 SD |
19 | * Authors: |
20 | * Srikar Dronamraju | |
21 | * Jim Keniston | |
90eec103 | 22 | * Copyright (C) 2011-2012 Red Hat, Inc., Peter Zijlstra |
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> | |
6e84f315 | 30 | #include <linux/sched/mm.h> |
f7ccbae4 | 31 | #include <linux/sched/coredump.h> |
e8440c14 | 32 | #include <linux/export.h> |
2b144498 SD |
33 | #include <linux/rmap.h> /* anon_vma_prepare */ |
34 | #include <linux/mmu_notifier.h> /* set_pte_at_notify */ | |
35 | #include <linux/swap.h> /* try_to_free_swap */ | |
0326f5a9 SD |
36 | #include <linux/ptrace.h> /* user_enable_single_step */ |
37 | #include <linux/kdebug.h> /* notifier mechanism */ | |
194f8dcb | 38 | #include "../../mm/internal.h" /* munlock_vma_page */ |
32cdba1e | 39 | #include <linux/percpu-rwsem.h> |
aa59c53f | 40 | #include <linux/task_work.h> |
40814f68 | 41 | #include <linux/shmem_fs.h> |
7b2d81d4 | 42 | |
2b144498 SD |
43 | #include <linux/uprobes.h> |
44 | ||
d4b3b638 SD |
45 | #define UINSNS_PER_PAGE (PAGE_SIZE/UPROBE_XOL_SLOT_BYTES) |
46 | #define MAX_UPROBE_XOL_SLOTS UINSNS_PER_PAGE | |
47 | ||
2b144498 | 48 | static struct rb_root uprobes_tree = RB_ROOT; |
441f1eb7 ON |
49 | /* |
50 | * allows us to skip the uprobe_mmap if there are no uprobe events active | |
51 | * at this time. Probably a fine grained per inode count is better? | |
52 | */ | |
53 | #define no_uprobe_events() RB_EMPTY_ROOT(&uprobes_tree) | |
7b2d81d4 | 54 | |
2b144498 SD |
55 | static DEFINE_SPINLOCK(uprobes_treelock); /* serialize rbtree access */ |
56 | ||
57 | #define UPROBES_HASH_SZ 13 | |
2b144498 SD |
58 | /* serialize uprobe->pending_list */ |
59 | static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ]; | |
7b2d81d4 | 60 | #define uprobes_mmap_hash(v) (&uprobes_mmap_mutex[((unsigned long)(v)) % UPROBES_HASH_SZ]) |
2b144498 | 61 | |
32cdba1e ON |
62 | static struct percpu_rw_semaphore dup_mmap_sem; |
63 | ||
cb9a19fe | 64 | /* Have a copy of original instruction */ |
71434f2f | 65 | #define UPROBE_COPY_INSN 0 |
cb9a19fe | 66 | |
3ff54efd SD |
67 | struct uprobe { |
68 | struct rb_node rb_node; /* node in the rb tree */ | |
69 | atomic_t ref; | |
e591c8d7 | 70 | struct rw_semaphore register_rwsem; |
3ff54efd SD |
71 | struct rw_semaphore consumer_rwsem; |
72 | struct list_head pending_list; | |
73 | struct uprobe_consumer *consumers; | |
74 | struct inode *inode; /* Also hold a ref to inode */ | |
75 | loff_t offset; | |
71434f2f | 76 | unsigned long flags; |
ad439356 ON |
77 | |
78 | /* | |
79 | * The generic code assumes that it has two members of unknown type | |
80 | * owned by the arch-specific code: | |
81 | * | |
82 | * insn - copy_insn() saves the original instruction here for | |
83 | * arch_uprobe_analyze_insn(). | |
84 | * | |
85 | * ixol - potentially modified instruction to execute out of | |
86 | * line, copied to xol_area by xol_get_insn_slot(). | |
87 | */ | |
3ff54efd SD |
88 | struct arch_uprobe arch; |
89 | }; | |
90 | ||
c912dae6 | 91 | /* |
ad439356 ON |
92 | * Execute out of line area: anonymous executable mapping installed |
93 | * by the probed task to execute the copy of the original instruction | |
94 | * mangled by set_swbp(). | |
95 | * | |
c912dae6 ON |
96 | * On a breakpoint hit, thread contests for a slot. It frees the |
97 | * slot after singlestep. Currently a fixed number of slots are | |
98 | * allocated. | |
99 | */ | |
100 | struct xol_area { | |
704bde3c ON |
101 | wait_queue_head_t wq; /* if all slots are busy */ |
102 | atomic_t slot_count; /* number of in-use slots */ | |
103 | unsigned long *bitmap; /* 0 = free slot */ | |
c912dae6 | 104 | |
704bde3c ON |
105 | struct vm_special_mapping xol_mapping; |
106 | struct page *pages[2]; | |
c912dae6 ON |
107 | /* |
108 | * We keep the vma's vm_start rather than a pointer to the vma | |
109 | * itself. The probed process or a naughty kernel module could make | |
110 | * the vma go away, and we must handle that reasonably gracefully. | |
111 | */ | |
704bde3c | 112 | unsigned long vaddr; /* Page(s) of instruction slots */ |
c912dae6 ON |
113 | }; |
114 | ||
2b144498 SD |
115 | /* |
116 | * valid_vma: Verify if the specified vma is an executable vma | |
117 | * Relax restrictions while unregistering: vm_flags might have | |
118 | * changed after breakpoint was inserted. | |
119 | * - is_register: indicates if we are in register context. | |
120 | * - Return 1 if the specified virtual address is in an | |
121 | * executable vma. | |
122 | */ | |
123 | static bool valid_vma(struct vm_area_struct *vma, bool is_register) | |
124 | { | |
13f59c5e | 125 | vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_MAYSHARE; |
2b144498 | 126 | |
e40cfce6 ON |
127 | if (is_register) |
128 | flags |= VM_WRITE; | |
2b144498 | 129 | |
e40cfce6 | 130 | return vma->vm_file && (vma->vm_flags & flags) == VM_MAYEXEC; |
2b144498 SD |
131 | } |
132 | ||
57683f72 | 133 | static unsigned long offset_to_vaddr(struct vm_area_struct *vma, loff_t offset) |
2b144498 | 134 | { |
57683f72 | 135 | return vma->vm_start + offset - ((loff_t)vma->vm_pgoff << PAGE_SHIFT); |
2b144498 SD |
136 | } |
137 | ||
cb113b47 ON |
138 | static loff_t vaddr_to_offset(struct vm_area_struct *vma, unsigned long vaddr) |
139 | { | |
140 | return ((loff_t)vma->vm_pgoff << PAGE_SHIFT) + (vaddr - vma->vm_start); | |
141 | } | |
142 | ||
2b144498 SD |
143 | /** |
144 | * __replace_page - replace page in vma by new page. | |
145 | * based on replace_page in mm/ksm.c | |
146 | * | |
147 | * @vma: vma that holds the pte pointing to page | |
c517ee74 | 148 | * @addr: address the old @page is mapped at |
2b144498 SD |
149 | * @page: the cowed page we are replacing by kpage |
150 | * @kpage: the modified page we replace page by | |
151 | * | |
152 | * Returns 0 on success, -EFAULT on failure. | |
153 | */ | |
c517ee74 | 154 | static int __replace_page(struct vm_area_struct *vma, unsigned long addr, |
bdfaa2ee | 155 | struct page *old_page, struct page *new_page) |
2b144498 SD |
156 | { |
157 | struct mm_struct *mm = vma->vm_mm; | |
14fa2daa KS |
158 | struct page_vma_mapped_walk pvmw = { |
159 | .page = old_page, | |
160 | .vma = vma, | |
161 | .address = addr, | |
162 | }; | |
9f92448c | 163 | int err; |
6bdb913f HE |
164 | /* For mmu_notifiers */ |
165 | const unsigned long mmun_start = addr; | |
166 | const unsigned long mmun_end = addr + PAGE_SIZE; | |
00501b53 JW |
167 | struct mem_cgroup *memcg; |
168 | ||
14fa2daa KS |
169 | VM_BUG_ON_PAGE(PageTransHuge(old_page), old_page); |
170 | ||
bdfaa2ee | 171 | err = mem_cgroup_try_charge(new_page, vma->vm_mm, GFP_KERNEL, &memcg, |
f627c2f5 | 172 | false); |
00501b53 JW |
173 | if (err) |
174 | return err; | |
2b144498 | 175 | |
194f8dcb | 176 | /* For try_to_free_swap() and munlock_vma_page() below */ |
bdfaa2ee | 177 | lock_page(old_page); |
9f92448c | 178 | |
6bdb913f | 179 | mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); |
9f92448c | 180 | err = -EAGAIN; |
14fa2daa | 181 | if (!page_vma_mapped_walk(&pvmw)) { |
bdfaa2ee | 182 | mem_cgroup_cancel_charge(new_page, memcg, false); |
9f92448c | 183 | goto unlock; |
6c4687cc | 184 | } |
14fa2daa | 185 | VM_BUG_ON_PAGE(addr != pvmw.address, old_page); |
2b144498 | 186 | |
bdfaa2ee ON |
187 | get_page(new_page); |
188 | page_add_new_anon_rmap(new_page, vma, addr, false); | |
189 | mem_cgroup_commit_charge(new_page, memcg, false, false); | |
190 | lru_cache_add_active_or_unevictable(new_page, vma); | |
2b144498 | 191 | |
bdfaa2ee ON |
192 | if (!PageAnon(old_page)) { |
193 | dec_mm_counter(mm, mm_counter_file(old_page)); | |
7396fa81 SD |
194 | inc_mm_counter(mm, MM_ANONPAGES); |
195 | } | |
196 | ||
14fa2daa KS |
197 | flush_cache_page(vma, addr, pte_pfn(*pvmw.pte)); |
198 | ptep_clear_flush_notify(vma, addr, pvmw.pte); | |
199 | set_pte_at_notify(mm, addr, pvmw.pte, | |
200 | mk_pte(new_page, vma->vm_page_prot)); | |
2b144498 | 201 | |
bdfaa2ee ON |
202 | page_remove_rmap(old_page, false); |
203 | if (!page_mapped(old_page)) | |
204 | try_to_free_swap(old_page); | |
14fa2daa | 205 | page_vma_mapped_walk_done(&pvmw); |
2b144498 | 206 | |
194f8dcb | 207 | if (vma->vm_flags & VM_LOCKED) |
bdfaa2ee ON |
208 | munlock_vma_page(old_page); |
209 | put_page(old_page); | |
194f8dcb | 210 | |
9f92448c ON |
211 | err = 0; |
212 | unlock: | |
6bdb913f | 213 | mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); |
bdfaa2ee | 214 | unlock_page(old_page); |
9f92448c | 215 | return err; |
2b144498 SD |
216 | } |
217 | ||
218 | /** | |
5cb4ac3a | 219 | * is_swbp_insn - check if instruction is breakpoint instruction. |
2b144498 | 220 | * @insn: instruction to be checked. |
5cb4ac3a | 221 | * Default implementation of is_swbp_insn |
2b144498 SD |
222 | * Returns true if @insn is a breakpoint instruction. |
223 | */ | |
5cb4ac3a | 224 | bool __weak is_swbp_insn(uprobe_opcode_t *insn) |
2b144498 | 225 | { |
5cb4ac3a | 226 | return *insn == UPROBE_SWBP_INSN; |
2b144498 SD |
227 | } |
228 | ||
0908ad6e AM |
229 | /** |
230 | * is_trap_insn - check if instruction is breakpoint instruction. | |
231 | * @insn: instruction to be checked. | |
232 | * Default implementation of is_trap_insn | |
233 | * Returns true if @insn is a breakpoint instruction. | |
234 | * | |
235 | * This function is needed for the case where an architecture has multiple | |
236 | * trap instructions (like powerpc). | |
237 | */ | |
238 | bool __weak is_trap_insn(uprobe_opcode_t *insn) | |
239 | { | |
240 | return is_swbp_insn(insn); | |
241 | } | |
242 | ||
ab0d805c | 243 | static void copy_from_page(struct page *page, unsigned long vaddr, void *dst, int len) |
cceb55aa ON |
244 | { |
245 | void *kaddr = kmap_atomic(page); | |
ab0d805c | 246 | memcpy(dst, kaddr + (vaddr & ~PAGE_MASK), len); |
cceb55aa ON |
247 | kunmap_atomic(kaddr); |
248 | } | |
249 | ||
5669ccee ON |
250 | static void copy_to_page(struct page *page, unsigned long vaddr, const void *src, int len) |
251 | { | |
252 | void *kaddr = kmap_atomic(page); | |
253 | memcpy(kaddr + (vaddr & ~PAGE_MASK), src, len); | |
254 | kunmap_atomic(kaddr); | |
255 | } | |
256 | ||
ed6f6a50 ON |
257 | static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *new_opcode) |
258 | { | |
259 | uprobe_opcode_t old_opcode; | |
260 | bool is_swbp; | |
261 | ||
0908ad6e AM |
262 | /* |
263 | * Note: We only check if the old_opcode is UPROBE_SWBP_INSN here. | |
264 | * We do not check if it is any other 'trap variant' which could | |
265 | * be conditional trap instruction such as the one powerpc supports. | |
266 | * | |
267 | * The logic is that we do not care if the underlying instruction | |
268 | * is a trap variant; uprobes always wins over any other (gdb) | |
269 | * breakpoint. | |
270 | */ | |
ab0d805c | 271 | copy_from_page(page, vaddr, &old_opcode, UPROBE_SWBP_INSN_SIZE); |
ed6f6a50 ON |
272 | is_swbp = is_swbp_insn(&old_opcode); |
273 | ||
274 | if (is_swbp_insn(new_opcode)) { | |
275 | if (is_swbp) /* register: already installed? */ | |
276 | return 0; | |
277 | } else { | |
278 | if (!is_swbp) /* unregister: was it changed by us? */ | |
076a365b | 279 | return 0; |
ed6f6a50 ON |
280 | } |
281 | ||
282 | return 1; | |
283 | } | |
284 | ||
2b144498 SD |
285 | /* |
286 | * NOTE: | |
287 | * Expect the breakpoint instruction to be the smallest size instruction for | |
288 | * the architecture. If an arch has variable length instruction and the | |
289 | * breakpoint instruction is not of the smallest length instruction | |
0908ad6e | 290 | * supported by that architecture then we need to modify is_trap_at_addr and |
f72d41fa ON |
291 | * uprobe_write_opcode accordingly. This would never be a problem for archs |
292 | * that have fixed length instructions. | |
29dedee0 | 293 | * |
f72d41fa | 294 | * uprobe_write_opcode - write the opcode at a given virtual address. |
2b144498 | 295 | * @mm: the probed process address space. |
2b144498 SD |
296 | * @vaddr: the virtual address to store the opcode. |
297 | * @opcode: opcode to be written at @vaddr. | |
298 | * | |
29dedee0 | 299 | * Called with mm->mmap_sem held for write. |
2b144498 SD |
300 | * Return 0 (success) or a negative errno. |
301 | */ | |
f72d41fa | 302 | int uprobe_write_opcode(struct mm_struct *mm, unsigned long vaddr, |
cceb55aa | 303 | uprobe_opcode_t opcode) |
2b144498 SD |
304 | { |
305 | struct page *old_page, *new_page; | |
2b144498 | 306 | struct vm_area_struct *vma; |
2b144498 | 307 | int ret; |
f403072c | 308 | |
5323ce71 | 309 | retry: |
2b144498 | 310 | /* Read the page with vaddr into memory */ |
c8394812 KS |
311 | ret = get_user_pages_remote(NULL, mm, vaddr, 1, |
312 | FOLL_FORCE | FOLL_SPLIT, &old_page, &vma, NULL); | |
2b144498 SD |
313 | if (ret <= 0) |
314 | return ret; | |
7b2d81d4 | 315 | |
ed6f6a50 ON |
316 | ret = verify_opcode(old_page, vaddr, &opcode); |
317 | if (ret <= 0) | |
318 | goto put_old; | |
319 | ||
29dedee0 ON |
320 | ret = anon_vma_prepare(vma); |
321 | if (ret) | |
322 | goto put_old; | |
323 | ||
2b144498 SD |
324 | ret = -ENOMEM; |
325 | new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr); | |
326 | if (!new_page) | |
9f92448c | 327 | goto put_old; |
2b144498 | 328 | |
29dedee0 | 329 | __SetPageUptodate(new_page); |
3f47107c ON |
330 | copy_highpage(new_page, old_page); |
331 | copy_to_page(new_page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE); | |
2b144498 | 332 | |
c517ee74 | 333 | ret = __replace_page(vma, vaddr, old_page, new_page); |
09cbfeaf | 334 | put_page(new_page); |
9f92448c | 335 | put_old: |
7b2d81d4 IM |
336 | put_page(old_page); |
337 | ||
5323ce71 ON |
338 | if (unlikely(ret == -EAGAIN)) |
339 | goto retry; | |
2b144498 SD |
340 | return ret; |
341 | } | |
342 | ||
2b144498 | 343 | /** |
5cb4ac3a | 344 | * set_swbp - store breakpoint at a given address. |
e3343e6a | 345 | * @auprobe: arch specific probepoint information. |
2b144498 | 346 | * @mm: the probed process address space. |
2b144498 SD |
347 | * @vaddr: the virtual address to insert the opcode. |
348 | * | |
349 | * For mm @mm, store the breakpoint instruction at @vaddr. | |
350 | * Return 0 (success) or a negative errno. | |
351 | */ | |
5cb4ac3a | 352 | int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) |
2b144498 | 353 | { |
f72d41fa | 354 | return uprobe_write_opcode(mm, vaddr, UPROBE_SWBP_INSN); |
2b144498 SD |
355 | } |
356 | ||
357 | /** | |
358 | * set_orig_insn - Restore the original instruction. | |
359 | * @mm: the probed process address space. | |
e3343e6a | 360 | * @auprobe: arch specific probepoint information. |
2b144498 | 361 | * @vaddr: the virtual address to insert the opcode. |
2b144498 SD |
362 | * |
363 | * For mm @mm, restore the original opcode (opcode) at @vaddr. | |
364 | * Return 0 (success) or a negative errno. | |
365 | */ | |
7b2d81d4 | 366 | int __weak |
ded86e7c | 367 | set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) |
2b144498 | 368 | { |
803200e2 | 369 | return uprobe_write_opcode(mm, vaddr, *(uprobe_opcode_t *)&auprobe->insn); |
2b144498 SD |
370 | } |
371 | ||
f231722a ON |
372 | static struct uprobe *get_uprobe(struct uprobe *uprobe) |
373 | { | |
374 | atomic_inc(&uprobe->ref); | |
375 | return uprobe; | |
376 | } | |
377 | ||
378 | static void put_uprobe(struct uprobe *uprobe) | |
379 | { | |
380 | if (atomic_dec_and_test(&uprobe->ref)) | |
381 | kfree(uprobe); | |
382 | } | |
383 | ||
2b144498 SD |
384 | static int match_uprobe(struct uprobe *l, struct uprobe *r) |
385 | { | |
386 | if (l->inode < r->inode) | |
387 | return -1; | |
7b2d81d4 | 388 | |
2b144498 SD |
389 | if (l->inode > r->inode) |
390 | return 1; | |
2b144498 | 391 | |
7b2d81d4 IM |
392 | if (l->offset < r->offset) |
393 | return -1; | |
394 | ||
395 | if (l->offset > r->offset) | |
396 | return 1; | |
2b144498 SD |
397 | |
398 | return 0; | |
399 | } | |
400 | ||
401 | static struct uprobe *__find_uprobe(struct inode *inode, loff_t offset) | |
402 | { | |
403 | struct uprobe u = { .inode = inode, .offset = offset }; | |
404 | struct rb_node *n = uprobes_tree.rb_node; | |
405 | struct uprobe *uprobe; | |
406 | int match; | |
407 | ||
408 | while (n) { | |
409 | uprobe = rb_entry(n, struct uprobe, rb_node); | |
410 | match = match_uprobe(&u, uprobe); | |
f231722a ON |
411 | if (!match) |
412 | return get_uprobe(uprobe); | |
7b2d81d4 | 413 | |
2b144498 SD |
414 | if (match < 0) |
415 | n = n->rb_left; | |
416 | else | |
417 | n = n->rb_right; | |
418 | } | |
419 | return NULL; | |
420 | } | |
421 | ||
422 | /* | |
423 | * Find a uprobe corresponding to a given inode:offset | |
424 | * Acquires uprobes_treelock | |
425 | */ | |
426 | static struct uprobe *find_uprobe(struct inode *inode, loff_t offset) | |
427 | { | |
428 | struct uprobe *uprobe; | |
2b144498 | 429 | |
6f47caa0 | 430 | spin_lock(&uprobes_treelock); |
2b144498 | 431 | uprobe = __find_uprobe(inode, offset); |
6f47caa0 | 432 | spin_unlock(&uprobes_treelock); |
7b2d81d4 | 433 | |
2b144498 SD |
434 | return uprobe; |
435 | } | |
436 | ||
437 | static struct uprobe *__insert_uprobe(struct uprobe *uprobe) | |
438 | { | |
439 | struct rb_node **p = &uprobes_tree.rb_node; | |
440 | struct rb_node *parent = NULL; | |
441 | struct uprobe *u; | |
442 | int match; | |
443 | ||
444 | while (*p) { | |
445 | parent = *p; | |
446 | u = rb_entry(parent, struct uprobe, rb_node); | |
447 | match = match_uprobe(uprobe, u); | |
f231722a ON |
448 | if (!match) |
449 | return get_uprobe(u); | |
2b144498 SD |
450 | |
451 | if (match < 0) | |
452 | p = &parent->rb_left; | |
453 | else | |
454 | p = &parent->rb_right; | |
455 | ||
456 | } | |
7b2d81d4 | 457 | |
2b144498 SD |
458 | u = NULL; |
459 | rb_link_node(&uprobe->rb_node, parent, p); | |
460 | rb_insert_color(&uprobe->rb_node, &uprobes_tree); | |
461 | /* get access + creation ref */ | |
462 | atomic_set(&uprobe->ref, 2); | |
7b2d81d4 | 463 | |
2b144498 SD |
464 | return u; |
465 | } | |
466 | ||
467 | /* | |
7b2d81d4 | 468 | * Acquire uprobes_treelock. |
2b144498 SD |
469 | * Matching uprobe already exists in rbtree; |
470 | * increment (access refcount) and return the matching uprobe. | |
471 | * | |
472 | * No matching uprobe; insert the uprobe in rb_tree; | |
473 | * get a double refcount (access + creation) and return NULL. | |
474 | */ | |
475 | static struct uprobe *insert_uprobe(struct uprobe *uprobe) | |
476 | { | |
2b144498 SD |
477 | struct uprobe *u; |
478 | ||
6f47caa0 | 479 | spin_lock(&uprobes_treelock); |
2b144498 | 480 | u = __insert_uprobe(uprobe); |
6f47caa0 | 481 | spin_unlock(&uprobes_treelock); |
7b2d81d4 | 482 | |
2b144498 SD |
483 | return u; |
484 | } | |
485 | ||
2b144498 SD |
486 | static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) |
487 | { | |
488 | struct uprobe *uprobe, *cur_uprobe; | |
489 | ||
490 | uprobe = kzalloc(sizeof(struct uprobe), GFP_KERNEL); | |
491 | if (!uprobe) | |
492 | return NULL; | |
493 | ||
494 | uprobe->inode = igrab(inode); | |
495 | uprobe->offset = offset; | |
e591c8d7 | 496 | init_rwsem(&uprobe->register_rwsem); |
2b144498 | 497 | init_rwsem(&uprobe->consumer_rwsem); |
2b144498 SD |
498 | |
499 | /* add to uprobes_tree, sorted on inode:offset */ | |
500 | cur_uprobe = insert_uprobe(uprobe); | |
2b144498 SD |
501 | /* a uprobe exists for this inode:offset combination */ |
502 | if (cur_uprobe) { | |
503 | kfree(uprobe); | |
504 | uprobe = cur_uprobe; | |
505 | iput(inode); | |
7b2d81d4 IM |
506 | } |
507 | ||
2b144498 SD |
508 | return uprobe; |
509 | } | |
510 | ||
9a98e03c | 511 | static void consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc) |
2b144498 SD |
512 | { |
513 | down_write(&uprobe->consumer_rwsem); | |
e3343e6a SD |
514 | uc->next = uprobe->consumers; |
515 | uprobe->consumers = uc; | |
2b144498 | 516 | up_write(&uprobe->consumer_rwsem); |
2b144498 SD |
517 | } |
518 | ||
519 | /* | |
e3343e6a SD |
520 | * For uprobe @uprobe, delete the consumer @uc. |
521 | * Return true if the @uc is deleted successfully | |
2b144498 SD |
522 | * or return false. |
523 | */ | |
e3343e6a | 524 | static bool consumer_del(struct uprobe *uprobe, struct uprobe_consumer *uc) |
2b144498 SD |
525 | { |
526 | struct uprobe_consumer **con; | |
527 | bool ret = false; | |
528 | ||
529 | down_write(&uprobe->consumer_rwsem); | |
530 | for (con = &uprobe->consumers; *con; con = &(*con)->next) { | |
e3343e6a SD |
531 | if (*con == uc) { |
532 | *con = uc->next; | |
2b144498 SD |
533 | ret = true; |
534 | break; | |
535 | } | |
536 | } | |
537 | up_write(&uprobe->consumer_rwsem); | |
7b2d81d4 | 538 | |
2b144498 SD |
539 | return ret; |
540 | } | |
541 | ||
2ded0980 ON |
542 | static int __copy_insn(struct address_space *mapping, struct file *filp, |
543 | void *insn, int nbytes, loff_t offset) | |
2b144498 | 544 | { |
2b144498 | 545 | struct page *page; |
2b144498 | 546 | /* |
40814f68 ON |
547 | * Ensure that the page that has the original instruction is populated |
548 | * and in page-cache. If ->readpage == NULL it must be shmem_mapping(), | |
549 | * see uprobe_register(). | |
2b144498 | 550 | */ |
40814f68 | 551 | if (mapping->a_ops->readpage) |
09cbfeaf | 552 | page = read_mapping_page(mapping, offset >> PAGE_SHIFT, filp); |
40814f68 | 553 | else |
09cbfeaf | 554 | page = shmem_read_mapping_page(mapping, offset >> PAGE_SHIFT); |
2b144498 SD |
555 | if (IS_ERR(page)) |
556 | return PTR_ERR(page); | |
557 | ||
2edb7b55 | 558 | copy_from_page(page, offset, insn, nbytes); |
09cbfeaf | 559 | put_page(page); |
7b2d81d4 | 560 | |
2b144498 SD |
561 | return 0; |
562 | } | |
563 | ||
d436615e | 564 | static int copy_insn(struct uprobe *uprobe, struct file *filp) |
2b144498 | 565 | { |
2ded0980 ON |
566 | struct address_space *mapping = uprobe->inode->i_mapping; |
567 | loff_t offs = uprobe->offset; | |
803200e2 ON |
568 | void *insn = &uprobe->arch.insn; |
569 | int size = sizeof(uprobe->arch.insn); | |
2ded0980 ON |
570 | int len, err = -EIO; |
571 | ||
572 | /* Copy only available bytes, -EIO if nothing was read */ | |
573 | do { | |
574 | if (offs >= i_size_read(uprobe->inode)) | |
575 | break; | |
576 | ||
577 | len = min_t(int, size, PAGE_SIZE - (offs & ~PAGE_MASK)); | |
578 | err = __copy_insn(mapping, filp, insn, len, offs); | |
fc36f595 | 579 | if (err) |
2ded0980 ON |
580 | break; |
581 | ||
582 | insn += len; | |
583 | offs += len; | |
584 | size -= len; | |
585 | } while (size); | |
586 | ||
587 | return err; | |
2b144498 SD |
588 | } |
589 | ||
cb9a19fe ON |
590 | static int prepare_uprobe(struct uprobe *uprobe, struct file *file, |
591 | struct mm_struct *mm, unsigned long vaddr) | |
592 | { | |
593 | int ret = 0; | |
594 | ||
71434f2f | 595 | if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) |
cb9a19fe ON |
596 | return ret; |
597 | ||
d4d3ccc6 ON |
598 | /* TODO: move this into _register, until then we abuse this sem. */ |
599 | down_write(&uprobe->consumer_rwsem); | |
71434f2f | 600 | if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) |
4710f05f ON |
601 | goto out; |
602 | ||
cb9a19fe ON |
603 | ret = copy_insn(uprobe, file); |
604 | if (ret) | |
605 | goto out; | |
606 | ||
607 | ret = -ENOTSUPP; | |
803200e2 | 608 | if (is_trap_insn((uprobe_opcode_t *)&uprobe->arch.insn)) |
cb9a19fe ON |
609 | goto out; |
610 | ||
611 | ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, vaddr); | |
612 | if (ret) | |
613 | goto out; | |
614 | ||
f72d41fa | 615 | /* uprobe_write_opcode() assumes we don't cross page boundary */ |
cb9a19fe ON |
616 | BUG_ON((uprobe->offset & ~PAGE_MASK) + |
617 | UPROBE_SWBP_INSN_SIZE > PAGE_SIZE); | |
618 | ||
619 | smp_wmb(); /* pairs with rmb() in find_active_uprobe() */ | |
71434f2f | 620 | set_bit(UPROBE_COPY_INSN, &uprobe->flags); |
cb9a19fe ON |
621 | |
622 | out: | |
d4d3ccc6 | 623 | up_write(&uprobe->consumer_rwsem); |
4710f05f | 624 | |
cb9a19fe ON |
625 | return ret; |
626 | } | |
627 | ||
8a7f2fa0 ON |
628 | static inline bool consumer_filter(struct uprobe_consumer *uc, |
629 | enum uprobe_filter_ctx ctx, struct mm_struct *mm) | |
806a98bd | 630 | { |
8a7f2fa0 | 631 | return !uc->filter || uc->filter(uc, ctx, mm); |
806a98bd ON |
632 | } |
633 | ||
8a7f2fa0 ON |
634 | static bool filter_chain(struct uprobe *uprobe, |
635 | enum uprobe_filter_ctx ctx, struct mm_struct *mm) | |
63633cbf | 636 | { |
1ff6fee5 ON |
637 | struct uprobe_consumer *uc; |
638 | bool ret = false; | |
639 | ||
640 | down_read(&uprobe->consumer_rwsem); | |
641 | for (uc = uprobe->consumers; uc; uc = uc->next) { | |
8a7f2fa0 | 642 | ret = consumer_filter(uc, ctx, mm); |
1ff6fee5 ON |
643 | if (ret) |
644 | break; | |
645 | } | |
646 | up_read(&uprobe->consumer_rwsem); | |
647 | ||
648 | return ret; | |
63633cbf ON |
649 | } |
650 | ||
e3343e6a SD |
651 | static int |
652 | install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, | |
816c03fb | 653 | struct vm_area_struct *vma, unsigned long vaddr) |
2b144498 | 654 | { |
f8ac4ec9 | 655 | bool first_uprobe; |
2b144498 SD |
656 | int ret; |
657 | ||
cb9a19fe ON |
658 | ret = prepare_uprobe(uprobe, vma->vm_file, mm, vaddr); |
659 | if (ret) | |
660 | return ret; | |
682968e0 | 661 | |
f8ac4ec9 ON |
662 | /* |
663 | * set MMF_HAS_UPROBES in advance for uprobe_pre_sstep_notifier(), | |
664 | * the task can hit this breakpoint right after __replace_page(). | |
665 | */ | |
666 | first_uprobe = !test_bit(MMF_HAS_UPROBES, &mm->flags); | |
667 | if (first_uprobe) | |
668 | set_bit(MMF_HAS_UPROBES, &mm->flags); | |
669 | ||
816c03fb | 670 | ret = set_swbp(&uprobe->arch, mm, vaddr); |
9f68f672 ON |
671 | if (!ret) |
672 | clear_bit(MMF_RECALC_UPROBES, &mm->flags); | |
673 | else if (first_uprobe) | |
f8ac4ec9 | 674 | clear_bit(MMF_HAS_UPROBES, &mm->flags); |
2b144498 SD |
675 | |
676 | return ret; | |
677 | } | |
678 | ||
076a365b | 679 | static int |
816c03fb | 680 | remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr) |
2b144498 | 681 | { |
9f68f672 | 682 | set_bit(MMF_RECALC_UPROBES, &mm->flags); |
076a365b | 683 | return set_orig_insn(&uprobe->arch, mm, vaddr); |
2b144498 SD |
684 | } |
685 | ||
06b7bcd8 ON |
686 | static inline bool uprobe_is_active(struct uprobe *uprobe) |
687 | { | |
688 | return !RB_EMPTY_NODE(&uprobe->rb_node); | |
689 | } | |
0326f5a9 | 690 | /* |
778b032d ON |
691 | * There could be threads that have already hit the breakpoint. They |
692 | * will recheck the current insn and restart if find_uprobe() fails. | |
693 | * See find_active_uprobe(). | |
0326f5a9 | 694 | */ |
2b144498 SD |
695 | static void delete_uprobe(struct uprobe *uprobe) |
696 | { | |
06b7bcd8 ON |
697 | if (WARN_ON(!uprobe_is_active(uprobe))) |
698 | return; | |
699 | ||
6f47caa0 | 700 | spin_lock(&uprobes_treelock); |
2b144498 | 701 | rb_erase(&uprobe->rb_node, &uprobes_tree); |
6f47caa0 | 702 | spin_unlock(&uprobes_treelock); |
06b7bcd8 | 703 | RB_CLEAR_NODE(&uprobe->rb_node); /* for uprobe_is_active() */ |
2b144498 SD |
704 | iput(uprobe->inode); |
705 | put_uprobe(uprobe); | |
2b144498 SD |
706 | } |
707 | ||
26872090 ON |
708 | struct map_info { |
709 | struct map_info *next; | |
710 | struct mm_struct *mm; | |
816c03fb | 711 | unsigned long vaddr; |
26872090 ON |
712 | }; |
713 | ||
714 | static inline struct map_info *free_map_info(struct map_info *info) | |
2b144498 | 715 | { |
26872090 ON |
716 | struct map_info *next = info->next; |
717 | kfree(info); | |
718 | return next; | |
719 | } | |
720 | ||
721 | static struct map_info * | |
722 | build_map_info(struct address_space *mapping, loff_t offset, bool is_register) | |
723 | { | |
724 | unsigned long pgoff = offset >> PAGE_SHIFT; | |
2b144498 | 725 | struct vm_area_struct *vma; |
26872090 ON |
726 | struct map_info *curr = NULL; |
727 | struct map_info *prev = NULL; | |
728 | struct map_info *info; | |
729 | int more = 0; | |
2b144498 | 730 | |
26872090 | 731 | again: |
4a23717a | 732 | i_mmap_lock_read(mapping); |
6b2dbba8 | 733 | vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { |
2b144498 SD |
734 | if (!valid_vma(vma, is_register)) |
735 | continue; | |
736 | ||
7a5bfb66 ON |
737 | if (!prev && !more) { |
738 | /* | |
c8c06efa | 739 | * Needs GFP_NOWAIT to avoid i_mmap_rwsem recursion through |
7a5bfb66 ON |
740 | * reclaim. This is optimistic, no harm done if it fails. |
741 | */ | |
742 | prev = kmalloc(sizeof(struct map_info), | |
743 | GFP_NOWAIT | __GFP_NOMEMALLOC | __GFP_NOWARN); | |
744 | if (prev) | |
745 | prev->next = NULL; | |
746 | } | |
26872090 ON |
747 | if (!prev) { |
748 | more++; | |
749 | continue; | |
2b144498 | 750 | } |
2b144498 | 751 | |
388f7934 | 752 | if (!mmget_not_zero(vma->vm_mm)) |
26872090 | 753 | continue; |
7b2d81d4 | 754 | |
26872090 ON |
755 | info = prev; |
756 | prev = prev->next; | |
757 | info->next = curr; | |
758 | curr = info; | |
2b144498 | 759 | |
26872090 | 760 | info->mm = vma->vm_mm; |
57683f72 | 761 | info->vaddr = offset_to_vaddr(vma, offset); |
26872090 | 762 | } |
4a23717a | 763 | i_mmap_unlock_read(mapping); |
2b144498 | 764 | |
26872090 ON |
765 | if (!more) |
766 | goto out; | |
767 | ||
768 | prev = curr; | |
769 | while (curr) { | |
770 | mmput(curr->mm); | |
771 | curr = curr->next; | |
772 | } | |
7b2d81d4 | 773 | |
26872090 ON |
774 | do { |
775 | info = kmalloc(sizeof(struct map_info), GFP_KERNEL); | |
776 | if (!info) { | |
777 | curr = ERR_PTR(-ENOMEM); | |
778 | goto out; | |
779 | } | |
780 | info->next = prev; | |
781 | prev = info; | |
782 | } while (--more); | |
783 | ||
784 | goto again; | |
785 | out: | |
786 | while (prev) | |
787 | prev = free_map_info(prev); | |
788 | return curr; | |
2b144498 SD |
789 | } |
790 | ||
bdf8647c ON |
791 | static int |
792 | register_for_each_vma(struct uprobe *uprobe, struct uprobe_consumer *new) | |
2b144498 | 793 | { |
bdf8647c | 794 | bool is_register = !!new; |
26872090 ON |
795 | struct map_info *info; |
796 | int err = 0; | |
2b144498 | 797 | |
32cdba1e | 798 | percpu_down_write(&dup_mmap_sem); |
26872090 ON |
799 | info = build_map_info(uprobe->inode->i_mapping, |
800 | uprobe->offset, is_register); | |
32cdba1e ON |
801 | if (IS_ERR(info)) { |
802 | err = PTR_ERR(info); | |
803 | goto out; | |
804 | } | |
7b2d81d4 | 805 | |
26872090 ON |
806 | while (info) { |
807 | struct mm_struct *mm = info->mm; | |
808 | struct vm_area_struct *vma; | |
7b2d81d4 | 809 | |
076a365b | 810 | if (err && is_register) |
26872090 | 811 | goto free; |
7b2d81d4 | 812 | |
77fc4af1 | 813 | down_write(&mm->mmap_sem); |
f4d6dfe5 ON |
814 | vma = find_vma(mm, info->vaddr); |
815 | if (!vma || !valid_vma(vma, is_register) || | |
f281769e | 816 | file_inode(vma->vm_file) != uprobe->inode) |
26872090 ON |
817 | goto unlock; |
818 | ||
f4d6dfe5 ON |
819 | if (vma->vm_start > info->vaddr || |
820 | vaddr_to_offset(vma, info->vaddr) != uprobe->offset) | |
26872090 | 821 | goto unlock; |
2b144498 | 822 | |
806a98bd ON |
823 | if (is_register) { |
824 | /* consult only the "caller", new consumer. */ | |
bdf8647c | 825 | if (consumer_filter(new, |
8a7f2fa0 | 826 | UPROBE_FILTER_REGISTER, mm)) |
806a98bd ON |
827 | err = install_breakpoint(uprobe, mm, vma, info->vaddr); |
828 | } else if (test_bit(MMF_HAS_UPROBES, &mm->flags)) { | |
8a7f2fa0 ON |
829 | if (!filter_chain(uprobe, |
830 | UPROBE_FILTER_UNREGISTER, mm)) | |
806a98bd ON |
831 | err |= remove_breakpoint(uprobe, mm, info->vaddr); |
832 | } | |
78f74116 | 833 | |
26872090 ON |
834 | unlock: |
835 | up_write(&mm->mmap_sem); | |
836 | free: | |
837 | mmput(mm); | |
838 | info = free_map_info(info); | |
2b144498 | 839 | } |
32cdba1e ON |
840 | out: |
841 | percpu_up_write(&dup_mmap_sem); | |
26872090 | 842 | return err; |
2b144498 SD |
843 | } |
844 | ||
9a98e03c | 845 | static int __uprobe_register(struct uprobe *uprobe, struct uprobe_consumer *uc) |
2b144498 | 846 | { |
9a98e03c | 847 | consumer_add(uprobe, uc); |
bdf8647c | 848 | return register_for_each_vma(uprobe, uc); |
2b144498 SD |
849 | } |
850 | ||
04aab9b2 | 851 | static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc) |
2b144498 | 852 | { |
04aab9b2 ON |
853 | int err; |
854 | ||
06d07139 | 855 | if (WARN_ON(!consumer_del(uprobe, uc))) |
04aab9b2 | 856 | return; |
2b144498 | 857 | |
bdf8647c | 858 | err = register_for_each_vma(uprobe, NULL); |
bb929284 ON |
859 | /* TODO : cant unregister? schedule a worker thread */ |
860 | if (!uprobe->consumers && !err) | |
861 | delete_uprobe(uprobe); | |
2b144498 SD |
862 | } |
863 | ||
864 | /* | |
7b2d81d4 | 865 | * uprobe_register - register a probe |
2b144498 SD |
866 | * @inode: the file in which the probe has to be placed. |
867 | * @offset: offset from the start of the file. | |
e3343e6a | 868 | * @uc: information on howto handle the probe.. |
2b144498 | 869 | * |
7b2d81d4 | 870 | * Apart from the access refcount, uprobe_register() takes a creation |
2b144498 SD |
871 | * refcount (thro alloc_uprobe) if and only if this @uprobe is getting |
872 | * inserted into the rbtree (i.e first consumer for a @inode:@offset | |
7b2d81d4 | 873 | * tuple). Creation refcount stops uprobe_unregister from freeing the |
2b144498 | 874 | * @uprobe even before the register operation is complete. Creation |
e3343e6a | 875 | * refcount is released when the last @uc for the @uprobe |
2b144498 SD |
876 | * unregisters. |
877 | * | |
878 | * Return errno if it cannot successully install probes | |
879 | * else return 0 (success) | |
880 | */ | |
e3343e6a | 881 | int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) |
2b144498 SD |
882 | { |
883 | struct uprobe *uprobe; | |
7b2d81d4 | 884 | int ret; |
2b144498 | 885 | |
ea024870 AA |
886 | /* Uprobe must have at least one set consumer */ |
887 | if (!uc->handler && !uc->ret_handler) | |
888 | return -EINVAL; | |
889 | ||
40814f68 ON |
890 | /* copy_insn() uses read_mapping_page() or shmem_read_mapping_page() */ |
891 | if (!inode->i_mapping->a_ops->readpage && !shmem_mapping(inode->i_mapping)) | |
41ccba02 | 892 | return -EIO; |
f0744af7 | 893 | /* Racy, just to catch the obvious mistakes */ |
2b144498 | 894 | if (offset > i_size_read(inode)) |
7b2d81d4 | 895 | return -EINVAL; |
2b144498 | 896 | |
66d06dff | 897 | retry: |
2b144498 | 898 | uprobe = alloc_uprobe(inode, offset); |
66d06dff ON |
899 | if (!uprobe) |
900 | return -ENOMEM; | |
901 | /* | |
902 | * We can race with uprobe_unregister()->delete_uprobe(). | |
903 | * Check uprobe_is_active() and retry if it is false. | |
904 | */ | |
905 | down_write(&uprobe->register_rwsem); | |
906 | ret = -EAGAIN; | |
907 | if (likely(uprobe_is_active(uprobe))) { | |
9a98e03c ON |
908 | ret = __uprobe_register(uprobe, uc); |
909 | if (ret) | |
04aab9b2 | 910 | __uprobe_unregister(uprobe, uc); |
2b144498 | 911 | } |
66d06dff ON |
912 | up_write(&uprobe->register_rwsem); |
913 | put_uprobe(uprobe); | |
2b144498 | 914 | |
66d06dff ON |
915 | if (unlikely(ret == -EAGAIN)) |
916 | goto retry; | |
2b144498 SD |
917 | return ret; |
918 | } | |
e8440c14 | 919 | EXPORT_SYMBOL_GPL(uprobe_register); |
2b144498 | 920 | |
bdf8647c ON |
921 | /* |
922 | * uprobe_apply - unregister a already registered probe. | |
923 | * @inode: the file in which the probe has to be removed. | |
924 | * @offset: offset from the start of the file. | |
925 | * @uc: consumer which wants to add more or remove some breakpoints | |
926 | * @add: add or remove the breakpoints | |
927 | */ | |
928 | int uprobe_apply(struct inode *inode, loff_t offset, | |
929 | struct uprobe_consumer *uc, bool add) | |
930 | { | |
931 | struct uprobe *uprobe; | |
932 | struct uprobe_consumer *con; | |
933 | int ret = -ENOENT; | |
934 | ||
935 | uprobe = find_uprobe(inode, offset); | |
06d07139 | 936 | if (WARN_ON(!uprobe)) |
bdf8647c ON |
937 | return ret; |
938 | ||
939 | down_write(&uprobe->register_rwsem); | |
940 | for (con = uprobe->consumers; con && con != uc ; con = con->next) | |
941 | ; | |
942 | if (con) | |
943 | ret = register_for_each_vma(uprobe, add ? uc : NULL); | |
944 | up_write(&uprobe->register_rwsem); | |
945 | put_uprobe(uprobe); | |
946 | ||
947 | return ret; | |
948 | } | |
949 | ||
2b144498 | 950 | /* |
7b2d81d4 | 951 | * uprobe_unregister - unregister a already registered probe. |
2b144498 SD |
952 | * @inode: the file in which the probe has to be removed. |
953 | * @offset: offset from the start of the file. | |
e3343e6a | 954 | * @uc: identify which probe if multiple probes are colocated. |
2b144498 | 955 | */ |
e3343e6a | 956 | void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) |
2b144498 | 957 | { |
7b2d81d4 | 958 | struct uprobe *uprobe; |
2b144498 | 959 | |
2b144498 | 960 | uprobe = find_uprobe(inode, offset); |
06d07139 | 961 | if (WARN_ON(!uprobe)) |
2b144498 SD |
962 | return; |
963 | ||
e591c8d7 | 964 | down_write(&uprobe->register_rwsem); |
04aab9b2 | 965 | __uprobe_unregister(uprobe, uc); |
e591c8d7 | 966 | up_write(&uprobe->register_rwsem); |
c91368c4 | 967 | put_uprobe(uprobe); |
2b144498 | 968 | } |
e8440c14 | 969 | EXPORT_SYMBOL_GPL(uprobe_unregister); |
2b144498 | 970 | |
da1816b1 ON |
971 | static int unapply_uprobe(struct uprobe *uprobe, struct mm_struct *mm) |
972 | { | |
973 | struct vm_area_struct *vma; | |
974 | int err = 0; | |
975 | ||
976 | down_read(&mm->mmap_sem); | |
977 | for (vma = mm->mmap; vma; vma = vma->vm_next) { | |
978 | unsigned long vaddr; | |
979 | loff_t offset; | |
980 | ||
981 | if (!valid_vma(vma, false) || | |
f281769e | 982 | file_inode(vma->vm_file) != uprobe->inode) |
da1816b1 ON |
983 | continue; |
984 | ||
985 | offset = (loff_t)vma->vm_pgoff << PAGE_SHIFT; | |
986 | if (uprobe->offset < offset || | |
987 | uprobe->offset >= offset + vma->vm_end - vma->vm_start) | |
988 | continue; | |
989 | ||
990 | vaddr = offset_to_vaddr(vma, uprobe->offset); | |
991 | err |= remove_breakpoint(uprobe, mm, vaddr); | |
992 | } | |
993 | up_read(&mm->mmap_sem); | |
994 | ||
995 | return err; | |
996 | } | |
997 | ||
891c3970 ON |
998 | static struct rb_node * |
999 | find_node_in_range(struct inode *inode, loff_t min, loff_t max) | |
2b144498 | 1000 | { |
2b144498 | 1001 | struct rb_node *n = uprobes_tree.rb_node; |
2b144498 SD |
1002 | |
1003 | while (n) { | |
891c3970 | 1004 | struct uprobe *u = rb_entry(n, struct uprobe, rb_node); |
2b144498 | 1005 | |
891c3970 | 1006 | if (inode < u->inode) { |
2b144498 | 1007 | n = n->rb_left; |
891c3970 | 1008 | } else if (inode > u->inode) { |
2b144498 | 1009 | n = n->rb_right; |
891c3970 ON |
1010 | } else { |
1011 | if (max < u->offset) | |
1012 | n = n->rb_left; | |
1013 | else if (min > u->offset) | |
1014 | n = n->rb_right; | |
1015 | else | |
1016 | break; | |
1017 | } | |
2b144498 | 1018 | } |
7b2d81d4 | 1019 | |
891c3970 | 1020 | return n; |
2b144498 SD |
1021 | } |
1022 | ||
1023 | /* | |
891c3970 | 1024 | * For a given range in vma, build a list of probes that need to be inserted. |
2b144498 | 1025 | */ |
891c3970 ON |
1026 | static void build_probe_list(struct inode *inode, |
1027 | struct vm_area_struct *vma, | |
1028 | unsigned long start, unsigned long end, | |
1029 | struct list_head *head) | |
2b144498 | 1030 | { |
891c3970 | 1031 | loff_t min, max; |
891c3970 ON |
1032 | struct rb_node *n, *t; |
1033 | struct uprobe *u; | |
7b2d81d4 | 1034 | |
891c3970 | 1035 | INIT_LIST_HEAD(head); |
cb113b47 | 1036 | min = vaddr_to_offset(vma, start); |
891c3970 | 1037 | max = min + (end - start) - 1; |
2b144498 | 1038 | |
6f47caa0 | 1039 | spin_lock(&uprobes_treelock); |
891c3970 ON |
1040 | n = find_node_in_range(inode, min, max); |
1041 | if (n) { | |
1042 | for (t = n; t; t = rb_prev(t)) { | |
1043 | u = rb_entry(t, struct uprobe, rb_node); | |
1044 | if (u->inode != inode || u->offset < min) | |
1045 | break; | |
1046 | list_add(&u->pending_list, head); | |
f231722a | 1047 | get_uprobe(u); |
891c3970 ON |
1048 | } |
1049 | for (t = n; (t = rb_next(t)); ) { | |
1050 | u = rb_entry(t, struct uprobe, rb_node); | |
1051 | if (u->inode != inode || u->offset > max) | |
1052 | break; | |
1053 | list_add(&u->pending_list, head); | |
f231722a | 1054 | get_uprobe(u); |
891c3970 | 1055 | } |
2b144498 | 1056 | } |
6f47caa0 | 1057 | spin_unlock(&uprobes_treelock); |
2b144498 SD |
1058 | } |
1059 | ||
1060 | /* | |
5e5be71a | 1061 | * Called from mmap_region/vma_adjust with mm->mmap_sem acquired. |
2b144498 | 1062 | * |
5e5be71a ON |
1063 | * Currently we ignore all errors and always return 0, the callers |
1064 | * can't handle the failure anyway. | |
2b144498 | 1065 | */ |
7b2d81d4 | 1066 | int uprobe_mmap(struct vm_area_struct *vma) |
2b144498 SD |
1067 | { |
1068 | struct list_head tmp_list; | |
665605a2 | 1069 | struct uprobe *uprobe, *u; |
2b144498 | 1070 | struct inode *inode; |
2b144498 | 1071 | |
441f1eb7 | 1072 | if (no_uprobe_events() || !valid_vma(vma, true)) |
7b2d81d4 | 1073 | return 0; |
2b144498 | 1074 | |
f281769e | 1075 | inode = file_inode(vma->vm_file); |
2b144498 | 1076 | if (!inode) |
7b2d81d4 | 1077 | return 0; |
2b144498 | 1078 | |
2b144498 | 1079 | mutex_lock(uprobes_mmap_hash(inode)); |
891c3970 | 1080 | build_probe_list(inode, vma, vma->vm_start, vma->vm_end, &tmp_list); |
806a98bd ON |
1081 | /* |
1082 | * We can race with uprobe_unregister(), this uprobe can be already | |
1083 | * removed. But in this case filter_chain() must return false, all | |
1084 | * consumers have gone away. | |
1085 | */ | |
665605a2 | 1086 | list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) { |
806a98bd | 1087 | if (!fatal_signal_pending(current) && |
8a7f2fa0 | 1088 | filter_chain(uprobe, UPROBE_FILTER_MMAP, vma->vm_mm)) { |
57683f72 | 1089 | unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset); |
5e5be71a | 1090 | install_breakpoint(uprobe, vma->vm_mm, vma, vaddr); |
2b144498 SD |
1091 | } |
1092 | put_uprobe(uprobe); | |
1093 | } | |
2b144498 SD |
1094 | mutex_unlock(uprobes_mmap_hash(inode)); |
1095 | ||
5e5be71a | 1096 | return 0; |
2b144498 SD |
1097 | } |
1098 | ||
9f68f672 ON |
1099 | static bool |
1100 | vma_has_uprobes(struct vm_area_struct *vma, unsigned long start, unsigned long end) | |
1101 | { | |
1102 | loff_t min, max; | |
1103 | struct inode *inode; | |
1104 | struct rb_node *n; | |
1105 | ||
f281769e | 1106 | inode = file_inode(vma->vm_file); |
9f68f672 ON |
1107 | |
1108 | min = vaddr_to_offset(vma, start); | |
1109 | max = min + (end - start) - 1; | |
1110 | ||
1111 | spin_lock(&uprobes_treelock); | |
1112 | n = find_node_in_range(inode, min, max); | |
1113 | spin_unlock(&uprobes_treelock); | |
1114 | ||
1115 | return !!n; | |
1116 | } | |
1117 | ||
682968e0 SD |
1118 | /* |
1119 | * Called in context of a munmap of a vma. | |
1120 | */ | |
cbc91f71 | 1121 | void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end) |
682968e0 | 1122 | { |
441f1eb7 | 1123 | if (no_uprobe_events() || !valid_vma(vma, false)) |
682968e0 SD |
1124 | return; |
1125 | ||
2fd611a9 ON |
1126 | if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */ |
1127 | return; | |
1128 | ||
9f68f672 ON |
1129 | if (!test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags) || |
1130 | test_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags)) | |
f8ac4ec9 ON |
1131 | return; |
1132 | ||
9f68f672 ON |
1133 | if (vma_has_uprobes(vma, start, end)) |
1134 | set_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags); | |
682968e0 SD |
1135 | } |
1136 | ||
d4b3b638 | 1137 | /* Slot allocation for XOL */ |
6441ec8b | 1138 | static int xol_add_vma(struct mm_struct *mm, struct xol_area *area) |
d4b3b638 | 1139 | { |
704bde3c ON |
1140 | struct vm_area_struct *vma; |
1141 | int ret; | |
d4b3b638 | 1142 | |
598fdc1d MH |
1143 | if (down_write_killable(&mm->mmap_sem)) |
1144 | return -EINTR; | |
1145 | ||
704bde3c ON |
1146 | if (mm->uprobes_state.xol_area) { |
1147 | ret = -EALREADY; | |
d4b3b638 | 1148 | goto fail; |
704bde3c | 1149 | } |
d4b3b638 | 1150 | |
af0d95af ON |
1151 | if (!area->vaddr) { |
1152 | /* Try to map as high as possible, this is only a hint. */ | |
1153 | area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE, | |
1154 | PAGE_SIZE, 0, 0); | |
1155 | if (area->vaddr & ~PAGE_MASK) { | |
1156 | ret = area->vaddr; | |
1157 | goto fail; | |
1158 | } | |
d4b3b638 SD |
1159 | } |
1160 | ||
704bde3c ON |
1161 | vma = _install_special_mapping(mm, area->vaddr, PAGE_SIZE, |
1162 | VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO, | |
1163 | &area->xol_mapping); | |
1164 | if (IS_ERR(vma)) { | |
1165 | ret = PTR_ERR(vma); | |
d4b3b638 | 1166 | goto fail; |
704bde3c | 1167 | } |
d4b3b638 | 1168 | |
704bde3c | 1169 | ret = 0; |
d4b3b638 SD |
1170 | smp_wmb(); /* pairs with get_xol_area() */ |
1171 | mm->uprobes_state.xol_area = area; | |
c8a82538 | 1172 | fail: |
d4b3b638 | 1173 | up_write(&mm->mmap_sem); |
d4b3b638 SD |
1174 | |
1175 | return ret; | |
1176 | } | |
1177 | ||
af0d95af | 1178 | static struct xol_area *__create_xol_area(unsigned long vaddr) |
d4b3b638 | 1179 | { |
9b545df8 | 1180 | struct mm_struct *mm = current->mm; |
e78aebfd | 1181 | uprobe_opcode_t insn = UPROBE_SWBP_INSN; |
6441ec8b | 1182 | struct xol_area *area; |
9b545df8 | 1183 | |
af0d95af | 1184 | area = kmalloc(sizeof(*area), GFP_KERNEL); |
d4b3b638 | 1185 | if (unlikely(!area)) |
c8a82538 | 1186 | goto out; |
d4b3b638 SD |
1187 | |
1188 | area->bitmap = kzalloc(BITS_TO_LONGS(UINSNS_PER_PAGE) * sizeof(long), GFP_KERNEL); | |
d4b3b638 | 1189 | if (!area->bitmap) |
c8a82538 ON |
1190 | goto free_area; |
1191 | ||
704bde3c | 1192 | area->xol_mapping.name = "[uprobes]"; |
869ae761 | 1193 | area->xol_mapping.fault = NULL; |
704bde3c | 1194 | area->xol_mapping.pages = area->pages; |
f58bea2f ON |
1195 | area->pages[0] = alloc_page(GFP_HIGHUSER); |
1196 | if (!area->pages[0]) | |
c8a82538 | 1197 | goto free_bitmap; |
f58bea2f | 1198 | area->pages[1] = NULL; |
d4b3b638 | 1199 | |
af0d95af | 1200 | area->vaddr = vaddr; |
6441ec8b ON |
1201 | init_waitqueue_head(&area->wq); |
1202 | /* Reserve the 1st slot for get_trampoline_vaddr() */ | |
e78aebfd | 1203 | set_bit(0, area->bitmap); |
e78aebfd | 1204 | atomic_set(&area->slot_count, 1); |
297e765e | 1205 | arch_uprobe_copy_ixol(area->pages[0], 0, &insn, UPROBE_SWBP_INSN_SIZE); |
e78aebfd | 1206 | |
6441ec8b | 1207 | if (!xol_add_vma(mm, area)) |
d4b3b638 SD |
1208 | return area; |
1209 | ||
f58bea2f | 1210 | __free_page(area->pages[0]); |
c8a82538 | 1211 | free_bitmap: |
d4b3b638 | 1212 | kfree(area->bitmap); |
c8a82538 | 1213 | free_area: |
d4b3b638 | 1214 | kfree(area); |
c8a82538 | 1215 | out: |
6441ec8b ON |
1216 | return NULL; |
1217 | } | |
1218 | ||
1219 | /* | |
1220 | * get_xol_area - Allocate process's xol_area if necessary. | |
1221 | * This area will be used for storing instructions for execution out of line. | |
1222 | * | |
1223 | * Returns the allocated area or NULL. | |
1224 | */ | |
1225 | static struct xol_area *get_xol_area(void) | |
1226 | { | |
1227 | struct mm_struct *mm = current->mm; | |
1228 | struct xol_area *area; | |
1229 | ||
1230 | if (!mm->uprobes_state.xol_area) | |
af0d95af | 1231 | __create_xol_area(0); |
6441ec8b | 1232 | |
9b545df8 | 1233 | area = mm->uprobes_state.xol_area; |
6441ec8b | 1234 | smp_read_barrier_depends(); /* pairs with wmb in xol_add_vma() */ |
9b545df8 | 1235 | return area; |
d4b3b638 SD |
1236 | } |
1237 | ||
1238 | /* | |
1239 | * uprobe_clear_state - Free the area allocated for slots. | |
1240 | */ | |
1241 | void uprobe_clear_state(struct mm_struct *mm) | |
1242 | { | |
1243 | struct xol_area *area = mm->uprobes_state.xol_area; | |
1244 | ||
1245 | if (!area) | |
1246 | return; | |
1247 | ||
f58bea2f | 1248 | put_page(area->pages[0]); |
d4b3b638 SD |
1249 | kfree(area->bitmap); |
1250 | kfree(area); | |
1251 | } | |
1252 | ||
32cdba1e ON |
1253 | void uprobe_start_dup_mmap(void) |
1254 | { | |
1255 | percpu_down_read(&dup_mmap_sem); | |
1256 | } | |
1257 | ||
1258 | void uprobe_end_dup_mmap(void) | |
1259 | { | |
1260 | percpu_up_read(&dup_mmap_sem); | |
1261 | } | |
1262 | ||
f8ac4ec9 ON |
1263 | void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm) |
1264 | { | |
9f68f672 | 1265 | if (test_bit(MMF_HAS_UPROBES, &oldmm->flags)) { |
f8ac4ec9 | 1266 | set_bit(MMF_HAS_UPROBES, &newmm->flags); |
9f68f672 ON |
1267 | /* unconditionally, dup_mmap() skips VM_DONTCOPY vmas */ |
1268 | set_bit(MMF_RECALC_UPROBES, &newmm->flags); | |
1269 | } | |
f8ac4ec9 ON |
1270 | } |
1271 | ||
d4b3b638 SD |
1272 | /* |
1273 | * - search for a free slot. | |
1274 | */ | |
1275 | static unsigned long xol_take_insn_slot(struct xol_area *area) | |
1276 | { | |
1277 | unsigned long slot_addr; | |
1278 | int slot_nr; | |
1279 | ||
1280 | do { | |
1281 | slot_nr = find_first_zero_bit(area->bitmap, UINSNS_PER_PAGE); | |
1282 | if (slot_nr < UINSNS_PER_PAGE) { | |
1283 | if (!test_and_set_bit(slot_nr, area->bitmap)) | |
1284 | break; | |
1285 | ||
1286 | slot_nr = UINSNS_PER_PAGE; | |
1287 | continue; | |
1288 | } | |
1289 | wait_event(area->wq, (atomic_read(&area->slot_count) < UINSNS_PER_PAGE)); | |
1290 | } while (slot_nr >= UINSNS_PER_PAGE); | |
1291 | ||
1292 | slot_addr = area->vaddr + (slot_nr * UPROBE_XOL_SLOT_BYTES); | |
1293 | atomic_inc(&area->slot_count); | |
1294 | ||
1295 | return slot_addr; | |
1296 | } | |
1297 | ||
1298 | /* | |
a6cb3f6d | 1299 | * xol_get_insn_slot - allocate a slot for xol. |
d4b3b638 SD |
1300 | * Returns the allocated slot address or 0. |
1301 | */ | |
a6cb3f6d | 1302 | static unsigned long xol_get_insn_slot(struct uprobe *uprobe) |
d4b3b638 SD |
1303 | { |
1304 | struct xol_area *area; | |
a6cb3f6d | 1305 | unsigned long xol_vaddr; |
d4b3b638 | 1306 | |
9b545df8 ON |
1307 | area = get_xol_area(); |
1308 | if (!area) | |
1309 | return 0; | |
d4b3b638 | 1310 | |
a6cb3f6d ON |
1311 | xol_vaddr = xol_take_insn_slot(area); |
1312 | if (unlikely(!xol_vaddr)) | |
d4b3b638 SD |
1313 | return 0; |
1314 | ||
f58bea2f | 1315 | arch_uprobe_copy_ixol(area->pages[0], xol_vaddr, |
72e6ae28 | 1316 | &uprobe->arch.ixol, sizeof(uprobe->arch.ixol)); |
d4b3b638 | 1317 | |
a6cb3f6d | 1318 | return xol_vaddr; |
d4b3b638 SD |
1319 | } |
1320 | ||
1321 | /* | |
1322 | * xol_free_insn_slot - If slot was earlier allocated by | |
1323 | * @xol_get_insn_slot(), make the slot available for | |
1324 | * subsequent requests. | |
1325 | */ | |
1326 | static void xol_free_insn_slot(struct task_struct *tsk) | |
1327 | { | |
1328 | struct xol_area *area; | |
1329 | unsigned long vma_end; | |
1330 | unsigned long slot_addr; | |
1331 | ||
1332 | if (!tsk->mm || !tsk->mm->uprobes_state.xol_area || !tsk->utask) | |
1333 | return; | |
1334 | ||
1335 | slot_addr = tsk->utask->xol_vaddr; | |
af4355e9 | 1336 | if (unlikely(!slot_addr)) |
d4b3b638 SD |
1337 | return; |
1338 | ||
1339 | area = tsk->mm->uprobes_state.xol_area; | |
1340 | vma_end = area->vaddr + PAGE_SIZE; | |
1341 | if (area->vaddr <= slot_addr && slot_addr < vma_end) { | |
1342 | unsigned long offset; | |
1343 | int slot_nr; | |
1344 | ||
1345 | offset = slot_addr - area->vaddr; | |
1346 | slot_nr = offset / UPROBE_XOL_SLOT_BYTES; | |
1347 | if (slot_nr >= UINSNS_PER_PAGE) | |
1348 | return; | |
1349 | ||
1350 | clear_bit(slot_nr, area->bitmap); | |
1351 | atomic_dec(&area->slot_count); | |
2a742ced | 1352 | smp_mb__after_atomic(); /* pairs with prepare_to_wait() */ |
d4b3b638 SD |
1353 | if (waitqueue_active(&area->wq)) |
1354 | wake_up(&area->wq); | |
1355 | ||
1356 | tsk->utask->xol_vaddr = 0; | |
1357 | } | |
1358 | } | |
1359 | ||
72e6ae28 VK |
1360 | void __weak arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr, |
1361 | void *src, unsigned long len) | |
1362 | { | |
1363 | /* Initialize the slot */ | |
1364 | copy_to_page(page, vaddr, src, len); | |
1365 | ||
1366 | /* | |
1367 | * We probably need flush_icache_user_range() but it needs vma. | |
1368 | * This should work on most of architectures by default. If | |
1369 | * architecture needs to do something different it can define | |
1370 | * its own version of the function. | |
1371 | */ | |
1372 | flush_dcache_page(page); | |
1373 | } | |
1374 | ||
0326f5a9 SD |
1375 | /** |
1376 | * uprobe_get_swbp_addr - compute address of swbp given post-swbp regs | |
1377 | * @regs: Reflects the saved state of the task after it has hit a breakpoint | |
1378 | * instruction. | |
1379 | * Return the address of the breakpoint instruction. | |
1380 | */ | |
1381 | unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs) | |
1382 | { | |
1383 | return instruction_pointer(regs) - UPROBE_SWBP_INSN_SIZE; | |
1384 | } | |
1385 | ||
b02ef20a ON |
1386 | unsigned long uprobe_get_trap_addr(struct pt_regs *regs) |
1387 | { | |
1388 | struct uprobe_task *utask = current->utask; | |
1389 | ||
1390 | if (unlikely(utask && utask->active_uprobe)) | |
1391 | return utask->vaddr; | |
1392 | ||
1393 | return instruction_pointer(regs); | |
1394 | } | |
1395 | ||
2bb5e840 ON |
1396 | static struct return_instance *free_ret_instance(struct return_instance *ri) |
1397 | { | |
1398 | struct return_instance *next = ri->next; | |
1399 | put_uprobe(ri->uprobe); | |
1400 | kfree(ri); | |
1401 | return next; | |
1402 | } | |
1403 | ||
0326f5a9 SD |
1404 | /* |
1405 | * Called with no locks held. | |
1406 | * Called in context of a exiting or a exec-ing thread. | |
1407 | */ | |
1408 | void uprobe_free_utask(struct task_struct *t) | |
1409 | { | |
1410 | struct uprobe_task *utask = t->utask; | |
2bb5e840 | 1411 | struct return_instance *ri; |
0326f5a9 | 1412 | |
0326f5a9 SD |
1413 | if (!utask) |
1414 | return; | |
1415 | ||
1416 | if (utask->active_uprobe) | |
1417 | put_uprobe(utask->active_uprobe); | |
1418 | ||
0dfd0eb8 | 1419 | ri = utask->return_instances; |
2bb5e840 ON |
1420 | while (ri) |
1421 | ri = free_ret_instance(ri); | |
0dfd0eb8 | 1422 | |
d4b3b638 | 1423 | xol_free_insn_slot(t); |
0326f5a9 SD |
1424 | kfree(utask); |
1425 | t->utask = NULL; | |
1426 | } | |
1427 | ||
0326f5a9 | 1428 | /* |
5a2df662 ON |
1429 | * Allocate a uprobe_task object for the task if if necessary. |
1430 | * Called when the thread hits a breakpoint. | |
0326f5a9 SD |
1431 | * |
1432 | * Returns: | |
1433 | * - pointer to new uprobe_task on success | |
1434 | * - NULL otherwise | |
1435 | */ | |
5a2df662 | 1436 | static struct uprobe_task *get_utask(void) |
0326f5a9 | 1437 | { |
5a2df662 ON |
1438 | if (!current->utask) |
1439 | current->utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL); | |
1440 | return current->utask; | |
0326f5a9 SD |
1441 | } |
1442 | ||
248d3a7b ON |
1443 | static int dup_utask(struct task_struct *t, struct uprobe_task *o_utask) |
1444 | { | |
1445 | struct uprobe_task *n_utask; | |
1446 | struct return_instance **p, *o, *n; | |
1447 | ||
1448 | n_utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL); | |
1449 | if (!n_utask) | |
1450 | return -ENOMEM; | |
1451 | t->utask = n_utask; | |
1452 | ||
1453 | p = &n_utask->return_instances; | |
1454 | for (o = o_utask->return_instances; o; o = o->next) { | |
1455 | n = kmalloc(sizeof(struct return_instance), GFP_KERNEL); | |
1456 | if (!n) | |
1457 | return -ENOMEM; | |
1458 | ||
1459 | *n = *o; | |
f231722a | 1460 | get_uprobe(n->uprobe); |
248d3a7b ON |
1461 | n->next = NULL; |
1462 | ||
1463 | *p = n; | |
1464 | p = &n->next; | |
1465 | n_utask->depth++; | |
1466 | } | |
1467 | ||
1468 | return 0; | |
1469 | } | |
1470 | ||
1471 | static void uprobe_warn(struct task_struct *t, const char *msg) | |
1472 | { | |
1473 | pr_warn("uprobe: %s:%d failed to %s\n", | |
1474 | current->comm, current->pid, msg); | |
1475 | } | |
1476 | ||
aa59c53f ON |
1477 | static void dup_xol_work(struct callback_head *work) |
1478 | { | |
aa59c53f ON |
1479 | if (current->flags & PF_EXITING) |
1480 | return; | |
1481 | ||
598fdc1d MH |
1482 | if (!__create_xol_area(current->utask->dup_xol_addr) && |
1483 | !fatal_signal_pending(current)) | |
aa59c53f ON |
1484 | uprobe_warn(current, "dup xol area"); |
1485 | } | |
1486 | ||
b68e0749 ON |
1487 | /* |
1488 | * Called in context of a new clone/fork from copy_process. | |
1489 | */ | |
3ab67966 | 1490 | void uprobe_copy_process(struct task_struct *t, unsigned long flags) |
b68e0749 | 1491 | { |
248d3a7b ON |
1492 | struct uprobe_task *utask = current->utask; |
1493 | struct mm_struct *mm = current->mm; | |
aa59c53f | 1494 | struct xol_area *area; |
248d3a7b | 1495 | |
b68e0749 | 1496 | t->utask = NULL; |
248d3a7b | 1497 | |
3ab67966 ON |
1498 | if (!utask || !utask->return_instances) |
1499 | return; | |
1500 | ||
1501 | if (mm == t->mm && !(flags & CLONE_VFORK)) | |
248d3a7b ON |
1502 | return; |
1503 | ||
1504 | if (dup_utask(t, utask)) | |
1505 | return uprobe_warn(t, "dup ret instances"); | |
aa59c53f ON |
1506 | |
1507 | /* The task can fork() after dup_xol_work() fails */ | |
1508 | area = mm->uprobes_state.xol_area; | |
1509 | if (!area) | |
1510 | return uprobe_warn(t, "dup xol area"); | |
1511 | ||
3ab67966 ON |
1512 | if (mm == t->mm) |
1513 | return; | |
1514 | ||
32473431 ON |
1515 | t->utask->dup_xol_addr = area->vaddr; |
1516 | init_task_work(&t->utask->dup_xol_work, dup_xol_work); | |
1517 | task_work_add(t, &t->utask->dup_xol_work, true); | |
b68e0749 ON |
1518 | } |
1519 | ||
e78aebfd AA |
1520 | /* |
1521 | * Current area->vaddr notion assume the trampoline address is always | |
1522 | * equal area->vaddr. | |
1523 | * | |
1524 | * Returns -1 in case the xol_area is not allocated. | |
1525 | */ | |
1526 | static unsigned long get_trampoline_vaddr(void) | |
1527 | { | |
1528 | struct xol_area *area; | |
1529 | unsigned long trampoline_vaddr = -1; | |
1530 | ||
1531 | area = current->mm->uprobes_state.xol_area; | |
1532 | smp_read_barrier_depends(); | |
1533 | if (area) | |
1534 | trampoline_vaddr = area->vaddr; | |
1535 | ||
1536 | return trampoline_vaddr; | |
1537 | } | |
1538 | ||
db087ef6 ON |
1539 | static void cleanup_return_instances(struct uprobe_task *utask, bool chained, |
1540 | struct pt_regs *regs) | |
a5b7e1a8 ON |
1541 | { |
1542 | struct return_instance *ri = utask->return_instances; | |
db087ef6 | 1543 | enum rp_check ctx = chained ? RP_CHECK_CHAIN_CALL : RP_CHECK_CALL; |
86dcb702 ON |
1544 | |
1545 | while (ri && !arch_uretprobe_is_alive(ri, ctx, regs)) { | |
a5b7e1a8 ON |
1546 | ri = free_ret_instance(ri); |
1547 | utask->depth--; | |
1548 | } | |
1549 | utask->return_instances = ri; | |
1550 | } | |
1551 | ||
0dfd0eb8 AA |
1552 | static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs) |
1553 | { | |
1554 | struct return_instance *ri; | |
1555 | struct uprobe_task *utask; | |
1556 | unsigned long orig_ret_vaddr, trampoline_vaddr; | |
db087ef6 | 1557 | bool chained; |
0dfd0eb8 AA |
1558 | |
1559 | if (!get_xol_area()) | |
1560 | return; | |
1561 | ||
1562 | utask = get_utask(); | |
1563 | if (!utask) | |
1564 | return; | |
1565 | ||
ded49c55 AA |
1566 | if (utask->depth >= MAX_URETPROBE_DEPTH) { |
1567 | printk_ratelimited(KERN_INFO "uprobe: omit uretprobe due to" | |
1568 | " nestedness limit pid/tgid=%d/%d\n", | |
1569 | current->pid, current->tgid); | |
1570 | return; | |
1571 | } | |
1572 | ||
6c58d0e4 | 1573 | ri = kmalloc(sizeof(struct return_instance), GFP_KERNEL); |
0dfd0eb8 | 1574 | if (!ri) |
6c58d0e4 | 1575 | return; |
0dfd0eb8 AA |
1576 | |
1577 | trampoline_vaddr = get_trampoline_vaddr(); | |
1578 | orig_ret_vaddr = arch_uretprobe_hijack_return_addr(trampoline_vaddr, regs); | |
1579 | if (orig_ret_vaddr == -1) | |
1580 | goto fail; | |
1581 | ||
a5b7e1a8 | 1582 | /* drop the entries invalidated by longjmp() */ |
db087ef6 ON |
1583 | chained = (orig_ret_vaddr == trampoline_vaddr); |
1584 | cleanup_return_instances(utask, chained, regs); | |
a5b7e1a8 | 1585 | |
0dfd0eb8 AA |
1586 | /* |
1587 | * We don't want to keep trampoline address in stack, rather keep the | |
1588 | * original return address of first caller thru all the consequent | |
1589 | * instances. This also makes breakpoint unwrapping easier. | |
1590 | */ | |
db087ef6 | 1591 | if (chained) { |
0dfd0eb8 AA |
1592 | if (!utask->return_instances) { |
1593 | /* | |
1594 | * This situation is not possible. Likely we have an | |
1595 | * attack from user-space. | |
1596 | */ | |
6c58d0e4 | 1597 | uprobe_warn(current, "handle tail call"); |
0dfd0eb8 AA |
1598 | goto fail; |
1599 | } | |
0dfd0eb8 AA |
1600 | orig_ret_vaddr = utask->return_instances->orig_ret_vaddr; |
1601 | } | |
1602 | ||
f231722a | 1603 | ri->uprobe = get_uprobe(uprobe); |
0dfd0eb8 | 1604 | ri->func = instruction_pointer(regs); |
7b868e48 | 1605 | ri->stack = user_stack_pointer(regs); |
0dfd0eb8 AA |
1606 | ri->orig_ret_vaddr = orig_ret_vaddr; |
1607 | ri->chained = chained; | |
1608 | ||
ded49c55 | 1609 | utask->depth++; |
0dfd0eb8 AA |
1610 | ri->next = utask->return_instances; |
1611 | utask->return_instances = ri; | |
1612 | ||
1613 | return; | |
0dfd0eb8 AA |
1614 | fail: |
1615 | kfree(ri); | |
1616 | } | |
1617 | ||
0326f5a9 SD |
1618 | /* Prepare to single-step probed instruction out of line. */ |
1619 | static int | |
a6cb3f6d | 1620 | pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long bp_vaddr) |
0326f5a9 | 1621 | { |
a6cb3f6d ON |
1622 | struct uprobe_task *utask; |
1623 | unsigned long xol_vaddr; | |
aba51024 | 1624 | int err; |
a6cb3f6d | 1625 | |
608e7427 ON |
1626 | utask = get_utask(); |
1627 | if (!utask) | |
1628 | return -ENOMEM; | |
a6cb3f6d ON |
1629 | |
1630 | xol_vaddr = xol_get_insn_slot(uprobe); | |
1631 | if (!xol_vaddr) | |
1632 | return -ENOMEM; | |
1633 | ||
1634 | utask->xol_vaddr = xol_vaddr; | |
1635 | utask->vaddr = bp_vaddr; | |
d4b3b638 | 1636 | |
aba51024 ON |
1637 | err = arch_uprobe_pre_xol(&uprobe->arch, regs); |
1638 | if (unlikely(err)) { | |
1639 | xol_free_insn_slot(current); | |
1640 | return err; | |
1641 | } | |
1642 | ||
608e7427 ON |
1643 | utask->active_uprobe = uprobe; |
1644 | utask->state = UTASK_SSTEP; | |
aba51024 | 1645 | return 0; |
0326f5a9 SD |
1646 | } |
1647 | ||
1648 | /* | |
1649 | * If we are singlestepping, then ensure this thread is not connected to | |
1650 | * non-fatal signals until completion of singlestep. When xol insn itself | |
1651 | * triggers the signal, restart the original insn even if the task is | |
1652 | * already SIGKILL'ed (since coredump should report the correct ip). This | |
1653 | * is even more important if the task has a handler for SIGSEGV/etc, The | |
1654 | * _same_ instruction should be repeated again after return from the signal | |
1655 | * handler, and SSTEP can never finish in this case. | |
1656 | */ | |
1657 | bool uprobe_deny_signal(void) | |
1658 | { | |
1659 | struct task_struct *t = current; | |
1660 | struct uprobe_task *utask = t->utask; | |
1661 | ||
1662 | if (likely(!utask || !utask->active_uprobe)) | |
1663 | return false; | |
1664 | ||
1665 | WARN_ON_ONCE(utask->state != UTASK_SSTEP); | |
1666 | ||
1667 | if (signal_pending(t)) { | |
1668 | spin_lock_irq(&t->sighand->siglock); | |
1669 | clear_tsk_thread_flag(t, TIF_SIGPENDING); | |
1670 | spin_unlock_irq(&t->sighand->siglock); | |
1671 | ||
1672 | if (__fatal_signal_pending(t) || arch_uprobe_xol_was_trapped(t)) { | |
1673 | utask->state = UTASK_SSTEP_TRAPPED; | |
1674 | set_tsk_thread_flag(t, TIF_UPROBE); | |
0326f5a9 SD |
1675 | } |
1676 | } | |
1677 | ||
1678 | return true; | |
1679 | } | |
1680 | ||
499a4f3e ON |
1681 | static void mmf_recalc_uprobes(struct mm_struct *mm) |
1682 | { | |
1683 | struct vm_area_struct *vma; | |
1684 | ||
1685 | for (vma = mm->mmap; vma; vma = vma->vm_next) { | |
1686 | if (!valid_vma(vma, false)) | |
1687 | continue; | |
1688 | /* | |
1689 | * This is not strictly accurate, we can race with | |
1690 | * uprobe_unregister() and see the already removed | |
1691 | * uprobe if delete_uprobe() was not yet called. | |
63633cbf | 1692 | * Or this uprobe can be filtered out. |
499a4f3e ON |
1693 | */ |
1694 | if (vma_has_uprobes(vma, vma->vm_start, vma->vm_end)) | |
1695 | return; | |
1696 | } | |
1697 | ||
1698 | clear_bit(MMF_HAS_UPROBES, &mm->flags); | |
1699 | } | |
1700 | ||
0908ad6e | 1701 | static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr) |
ec75fba9 ON |
1702 | { |
1703 | struct page *page; | |
1704 | uprobe_opcode_t opcode; | |
1705 | int result; | |
1706 | ||
1707 | pagefault_disable(); | |
bd28b145 | 1708 | result = __get_user(opcode, (uprobe_opcode_t __user *)vaddr); |
ec75fba9 ON |
1709 | pagefault_enable(); |
1710 | ||
1711 | if (likely(result == 0)) | |
1712 | goto out; | |
1713 | ||
1e987790 DH |
1714 | /* |
1715 | * The NULL 'tsk' here ensures that any faults that occur here | |
1716 | * will not be accounted to the task. 'mm' *is* current->mm, | |
1717 | * but we treat this as a 'remote' access since it is | |
1718 | * essentially a kernel access to the memory. | |
1719 | */ | |
9beae1ea | 1720 | result = get_user_pages_remote(NULL, mm, vaddr, 1, FOLL_FORCE, &page, |
5b56d49f | 1721 | NULL, NULL); |
ec75fba9 ON |
1722 | if (result < 0) |
1723 | return result; | |
1724 | ||
ab0d805c | 1725 | copy_from_page(page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE); |
ec75fba9 ON |
1726 | put_page(page); |
1727 | out: | |
0908ad6e AM |
1728 | /* This needs to return true for any variant of the trap insn */ |
1729 | return is_trap_insn(&opcode); | |
ec75fba9 ON |
1730 | } |
1731 | ||
d790d346 | 1732 | static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp) |
0326f5a9 | 1733 | { |
3a9ea052 ON |
1734 | struct mm_struct *mm = current->mm; |
1735 | struct uprobe *uprobe = NULL; | |
0326f5a9 | 1736 | struct vm_area_struct *vma; |
0326f5a9 | 1737 | |
0326f5a9 SD |
1738 | down_read(&mm->mmap_sem); |
1739 | vma = find_vma(mm, bp_vaddr); | |
3a9ea052 ON |
1740 | if (vma && vma->vm_start <= bp_vaddr) { |
1741 | if (valid_vma(vma, false)) { | |
f281769e | 1742 | struct inode *inode = file_inode(vma->vm_file); |
cb113b47 | 1743 | loff_t offset = vaddr_to_offset(vma, bp_vaddr); |
0326f5a9 | 1744 | |
3a9ea052 ON |
1745 | uprobe = find_uprobe(inode, offset); |
1746 | } | |
d790d346 ON |
1747 | |
1748 | if (!uprobe) | |
0908ad6e | 1749 | *is_swbp = is_trap_at_addr(mm, bp_vaddr); |
d790d346 ON |
1750 | } else { |
1751 | *is_swbp = -EFAULT; | |
0326f5a9 | 1752 | } |
499a4f3e ON |
1753 | |
1754 | if (!uprobe && test_and_clear_bit(MMF_RECALC_UPROBES, &mm->flags)) | |
1755 | mmf_recalc_uprobes(mm); | |
0326f5a9 SD |
1756 | up_read(&mm->mmap_sem); |
1757 | ||
3a9ea052 ON |
1758 | return uprobe; |
1759 | } | |
1760 | ||
da1816b1 ON |
1761 | static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs) |
1762 | { | |
1763 | struct uprobe_consumer *uc; | |
1764 | int remove = UPROBE_HANDLER_REMOVE; | |
0dfd0eb8 | 1765 | bool need_prep = false; /* prepare return uprobe, when needed */ |
da1816b1 ON |
1766 | |
1767 | down_read(&uprobe->register_rwsem); | |
1768 | for (uc = uprobe->consumers; uc; uc = uc->next) { | |
ea024870 | 1769 | int rc = 0; |
da1816b1 | 1770 | |
ea024870 AA |
1771 | if (uc->handler) { |
1772 | rc = uc->handler(uc, regs); | |
1773 | WARN(rc & ~UPROBE_HANDLER_MASK, | |
1774 | "bad rc=0x%x from %pf()\n", rc, uc->handler); | |
1775 | } | |
0dfd0eb8 AA |
1776 | |
1777 | if (uc->ret_handler) | |
1778 | need_prep = true; | |
1779 | ||
da1816b1 ON |
1780 | remove &= rc; |
1781 | } | |
1782 | ||
0dfd0eb8 AA |
1783 | if (need_prep && !remove) |
1784 | prepare_uretprobe(uprobe, regs); /* put bp at return */ | |
1785 | ||
da1816b1 ON |
1786 | if (remove && uprobe->consumers) { |
1787 | WARN_ON(!uprobe_is_active(uprobe)); | |
1788 | unapply_uprobe(uprobe, current->mm); | |
1789 | } | |
1790 | up_read(&uprobe->register_rwsem); | |
1791 | } | |
1792 | ||
fec8898d AA |
1793 | static void |
1794 | handle_uretprobe_chain(struct return_instance *ri, struct pt_regs *regs) | |
1795 | { | |
1796 | struct uprobe *uprobe = ri->uprobe; | |
1797 | struct uprobe_consumer *uc; | |
1798 | ||
1799 | down_read(&uprobe->register_rwsem); | |
1800 | for (uc = uprobe->consumers; uc; uc = uc->next) { | |
1801 | if (uc->ret_handler) | |
1802 | uc->ret_handler(uc, ri->func, regs); | |
1803 | } | |
1804 | up_read(&uprobe->register_rwsem); | |
1805 | } | |
1806 | ||
a83cfeb9 ON |
1807 | static struct return_instance *find_next_ret_chain(struct return_instance *ri) |
1808 | { | |
1809 | bool chained; | |
1810 | ||
1811 | do { | |
1812 | chained = ri->chained; | |
1813 | ri = ri->next; /* can't be NULL if chained */ | |
1814 | } while (chained); | |
1815 | ||
1816 | return ri; | |
1817 | } | |
1818 | ||
0b5256c7 | 1819 | static void handle_trampoline(struct pt_regs *regs) |
fec8898d AA |
1820 | { |
1821 | struct uprobe_task *utask; | |
a83cfeb9 | 1822 | struct return_instance *ri, *next; |
5eeb50de | 1823 | bool valid; |
fec8898d AA |
1824 | |
1825 | utask = current->utask; | |
1826 | if (!utask) | |
0b5256c7 | 1827 | goto sigill; |
fec8898d AA |
1828 | |
1829 | ri = utask->return_instances; | |
1830 | if (!ri) | |
0b5256c7 | 1831 | goto sigill; |
fec8898d | 1832 | |
a83cfeb9 | 1833 | do { |
5eeb50de ON |
1834 | /* |
1835 | * We should throw out the frames invalidated by longjmp(). | |
1836 | * If this chain is valid, then the next one should be alive | |
1837 | * or NULL; the latter case means that nobody but ri->func | |
1838 | * could hit this trampoline on return. TODO: sigaltstack(). | |
1839 | */ | |
1840 | next = find_next_ret_chain(ri); | |
86dcb702 | 1841 | valid = !next || arch_uretprobe_is_alive(next, RP_CHECK_RET, regs); |
5eeb50de ON |
1842 | |
1843 | instruction_pointer_set(regs, ri->orig_ret_vaddr); | |
1844 | do { | |
1845 | if (valid) | |
1846 | handle_uretprobe_chain(ri, regs); | |
1847 | ri = free_ret_instance(ri); | |
1848 | utask->depth--; | |
1849 | } while (ri != next); | |
1850 | } while (!valid); | |
fec8898d AA |
1851 | |
1852 | utask->return_instances = ri; | |
0b5256c7 ON |
1853 | return; |
1854 | ||
1855 | sigill: | |
1856 | uprobe_warn(current, "handle uretprobe, sending SIGILL."); | |
1857 | force_sig_info(SIGILL, SEND_SIG_FORCED, current); | |
fec8898d | 1858 | |
fec8898d AA |
1859 | } |
1860 | ||
6fe50a28 DL |
1861 | bool __weak arch_uprobe_ignore(struct arch_uprobe *aup, struct pt_regs *regs) |
1862 | { | |
1863 | return false; | |
1864 | } | |
1865 | ||
86dcb702 ON |
1866 | bool __weak arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx, |
1867 | struct pt_regs *regs) | |
97da8976 ON |
1868 | { |
1869 | return true; | |
1870 | } | |
1871 | ||
3a9ea052 ON |
1872 | /* |
1873 | * Run handler and ask thread to singlestep. | |
1874 | * Ensure all non-fatal signals cannot interrupt thread while it singlesteps. | |
1875 | */ | |
1876 | static void handle_swbp(struct pt_regs *regs) | |
1877 | { | |
3a9ea052 ON |
1878 | struct uprobe *uprobe; |
1879 | unsigned long bp_vaddr; | |
56bb4cf6 | 1880 | int uninitialized_var(is_swbp); |
3a9ea052 ON |
1881 | |
1882 | bp_vaddr = uprobe_get_swbp_addr(regs); | |
0b5256c7 ON |
1883 | if (bp_vaddr == get_trampoline_vaddr()) |
1884 | return handle_trampoline(regs); | |
fec8898d AA |
1885 | |
1886 | uprobe = find_active_uprobe(bp_vaddr, &is_swbp); | |
0326f5a9 | 1887 | if (!uprobe) { |
56bb4cf6 ON |
1888 | if (is_swbp > 0) { |
1889 | /* No matching uprobe; signal SIGTRAP. */ | |
1890 | send_sig(SIGTRAP, current, 0); | |
1891 | } else { | |
1892 | /* | |
1893 | * Either we raced with uprobe_unregister() or we can't | |
1894 | * access this memory. The latter is only possible if | |
1895 | * another thread plays with our ->mm. In both cases | |
1896 | * we can simply restart. If this vma was unmapped we | |
1897 | * can pretend this insn was not executed yet and get | |
1898 | * the (correct) SIGSEGV after restart. | |
1899 | */ | |
1900 | instruction_pointer_set(regs, bp_vaddr); | |
1901 | } | |
0326f5a9 SD |
1902 | return; |
1903 | } | |
74e59dfc ON |
1904 | |
1905 | /* change it in advance for ->handler() and restart */ | |
1906 | instruction_pointer_set(regs, bp_vaddr); | |
1907 | ||
142b18dd ON |
1908 | /* |
1909 | * TODO: move copy_insn/etc into _register and remove this hack. | |
1910 | * After we hit the bp, _unregister + _register can install the | |
1911 | * new and not-yet-analyzed uprobe at the same address, restart. | |
1912 | */ | |
1913 | smp_rmb(); /* pairs with wmb() in install_breakpoint() */ | |
71434f2f | 1914 | if (unlikely(!test_bit(UPROBE_COPY_INSN, &uprobe->flags))) |
74e59dfc | 1915 | goto out; |
0326f5a9 | 1916 | |
72fd293a ON |
1917 | /* Tracing handlers use ->utask to communicate with fetch methods */ |
1918 | if (!get_utask()) | |
1919 | goto out; | |
1920 | ||
6fe50a28 DL |
1921 | if (arch_uprobe_ignore(&uprobe->arch, regs)) |
1922 | goto out; | |
1923 | ||
0326f5a9 | 1924 | handler_chain(uprobe, regs); |
6fe50a28 | 1925 | |
8a6b1732 | 1926 | if (arch_uprobe_skip_sstep(&uprobe->arch, regs)) |
0578a970 | 1927 | goto out; |
0326f5a9 | 1928 | |
608e7427 | 1929 | if (!pre_ssout(uprobe, regs, bp_vaddr)) |
0326f5a9 | 1930 | return; |
0326f5a9 | 1931 | |
8a6b1732 | 1932 | /* arch_uprobe_skip_sstep() succeeded, or restart if can't singlestep */ |
0578a970 | 1933 | out: |
8bd87445 | 1934 | put_uprobe(uprobe); |
0326f5a9 SD |
1935 | } |
1936 | ||
1937 | /* | |
1938 | * Perform required fix-ups and disable singlestep. | |
1939 | * Allow pending signals to take effect. | |
1940 | */ | |
1941 | static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs) | |
1942 | { | |
1943 | struct uprobe *uprobe; | |
014940ba | 1944 | int err = 0; |
0326f5a9 SD |
1945 | |
1946 | uprobe = utask->active_uprobe; | |
1947 | if (utask->state == UTASK_SSTEP_ACK) | |
014940ba | 1948 | err = arch_uprobe_post_xol(&uprobe->arch, regs); |
0326f5a9 SD |
1949 | else if (utask->state == UTASK_SSTEP_TRAPPED) |
1950 | arch_uprobe_abort_xol(&uprobe->arch, regs); | |
1951 | else | |
1952 | WARN_ON_ONCE(1); | |
1953 | ||
1954 | put_uprobe(uprobe); | |
1955 | utask->active_uprobe = NULL; | |
1956 | utask->state = UTASK_RUNNING; | |
d4b3b638 | 1957 | xol_free_insn_slot(current); |
0326f5a9 SD |
1958 | |
1959 | spin_lock_irq(¤t->sighand->siglock); | |
1960 | recalc_sigpending(); /* see uprobe_deny_signal() */ | |
1961 | spin_unlock_irq(¤t->sighand->siglock); | |
014940ba ON |
1962 | |
1963 | if (unlikely(err)) { | |
1964 | uprobe_warn(current, "execute the probed insn, sending SIGILL."); | |
1965 | force_sig_info(SIGILL, SEND_SIG_FORCED, current); | |
1966 | } | |
0326f5a9 SD |
1967 | } |
1968 | ||
1969 | /* | |
1b08e907 ON |
1970 | * On breakpoint hit, breakpoint notifier sets the TIF_UPROBE flag and |
1971 | * allows the thread to return from interrupt. After that handle_swbp() | |
1972 | * sets utask->active_uprobe. | |
0326f5a9 | 1973 | * |
1b08e907 ON |
1974 | * On singlestep exception, singlestep notifier sets the TIF_UPROBE flag |
1975 | * and allows the thread to return from interrupt. | |
0326f5a9 SD |
1976 | * |
1977 | * While returning to userspace, thread notices the TIF_UPROBE flag and calls | |
1978 | * uprobe_notify_resume(). | |
1979 | */ | |
1980 | void uprobe_notify_resume(struct pt_regs *regs) | |
1981 | { | |
1982 | struct uprobe_task *utask; | |
1983 | ||
db023ea5 ON |
1984 | clear_thread_flag(TIF_UPROBE); |
1985 | ||
0326f5a9 | 1986 | utask = current->utask; |
1b08e907 | 1987 | if (utask && utask->active_uprobe) |
0326f5a9 | 1988 | handle_singlestep(utask, regs); |
1b08e907 ON |
1989 | else |
1990 | handle_swbp(regs); | |
0326f5a9 SD |
1991 | } |
1992 | ||
1993 | /* | |
1994 | * uprobe_pre_sstep_notifier gets called from interrupt context as part of | |
1995 | * notifier mechanism. Set TIF_UPROBE flag and indicate breakpoint hit. | |
1996 | */ | |
1997 | int uprobe_pre_sstep_notifier(struct pt_regs *regs) | |
1998 | { | |
0dfd0eb8 AA |
1999 | if (!current->mm) |
2000 | return 0; | |
2001 | ||
2002 | if (!test_bit(MMF_HAS_UPROBES, ¤t->mm->flags) && | |
2003 | (!current->utask || !current->utask->return_instances)) | |
0326f5a9 SD |
2004 | return 0; |
2005 | ||
0326f5a9 | 2006 | set_thread_flag(TIF_UPROBE); |
0326f5a9 SD |
2007 | return 1; |
2008 | } | |
2009 | ||
2010 | /* | |
2011 | * uprobe_post_sstep_notifier gets called in interrupt context as part of notifier | |
2012 | * mechanism. Set TIF_UPROBE flag and indicate completion of singlestep. | |
2013 | */ | |
2014 | int uprobe_post_sstep_notifier(struct pt_regs *regs) | |
2015 | { | |
2016 | struct uprobe_task *utask = current->utask; | |
2017 | ||
2018 | if (!current->mm || !utask || !utask->active_uprobe) | |
2019 | /* task is currently not uprobed */ | |
2020 | return 0; | |
2021 | ||
2022 | utask->state = UTASK_SSTEP_ACK; | |
2023 | set_thread_flag(TIF_UPROBE); | |
2024 | return 1; | |
2025 | } | |
2026 | ||
2027 | static struct notifier_block uprobe_exception_nb = { | |
2028 | .notifier_call = arch_uprobe_exception_notify, | |
2029 | .priority = INT_MAX-1, /* notified after kprobes, kgdb */ | |
2030 | }; | |
2031 | ||
2b144498 SD |
2032 | static int __init init_uprobes(void) |
2033 | { | |
2034 | int i; | |
2035 | ||
66d06dff | 2036 | for (i = 0; i < UPROBES_HASH_SZ; i++) |
2b144498 | 2037 | mutex_init(&uprobes_mmap_mutex[i]); |
0326f5a9 | 2038 | |
32cdba1e ON |
2039 | if (percpu_init_rwsem(&dup_mmap_sem)) |
2040 | return -ENOMEM; | |
2041 | ||
0326f5a9 | 2042 | return register_die_notifier(&uprobe_exception_nb); |
2b144498 | 2043 | } |
736e89d9 | 2044 | __initcall(init_uprobes); |