Commit | Line | Data |
---|---|---|
720e596a | 1 | // SPDX-License-Identifier: GPL-2.0+ |
2b144498 | 2 | /* |
7b2d81d4 | 3 | * User-space Probes (UProbes) |
2b144498 | 4 | * |
35aa621b | 5 | * Copyright (C) IBM Corporation, 2008-2012 |
2b144498 SD |
6 | * Authors: |
7 | * Srikar Dronamraju | |
8 | * Jim Keniston | |
90eec103 | 9 | * Copyright (C) 2011-2012 Red Hat, Inc., Peter Zijlstra |
2b144498 SD |
10 | */ |
11 | ||
12 | #include <linux/kernel.h> | |
13 | #include <linux/highmem.h> | |
14 | #include <linux/pagemap.h> /* read_mapping_page */ | |
15 | #include <linux/slab.h> | |
16 | #include <linux/sched.h> | |
6e84f315 | 17 | #include <linux/sched/mm.h> |
f7ccbae4 | 18 | #include <linux/sched/coredump.h> |
e8440c14 | 19 | #include <linux/export.h> |
2b144498 SD |
20 | #include <linux/rmap.h> /* anon_vma_prepare */ |
21 | #include <linux/mmu_notifier.h> /* set_pte_at_notify */ | |
22 | #include <linux/swap.h> /* try_to_free_swap */ | |
0326f5a9 SD |
23 | #include <linux/ptrace.h> /* user_enable_single_step */ |
24 | #include <linux/kdebug.h> /* notifier mechanism */ | |
194f8dcb | 25 | #include "../../mm/internal.h" /* munlock_vma_page */ |
32cdba1e | 26 | #include <linux/percpu-rwsem.h> |
aa59c53f | 27 | #include <linux/task_work.h> |
40814f68 | 28 | #include <linux/shmem_fs.h> |
7b2d81d4 | 29 | |
2b144498 SD |
30 | #include <linux/uprobes.h> |
31 | ||
d4b3b638 SD |
32 | #define UINSNS_PER_PAGE (PAGE_SIZE/UPROBE_XOL_SLOT_BYTES) |
33 | #define MAX_UPROBE_XOL_SLOTS UINSNS_PER_PAGE | |
34 | ||
2b144498 | 35 | static struct rb_root uprobes_tree = RB_ROOT; |
441f1eb7 ON |
36 | /* |
37 | * allows us to skip the uprobe_mmap if there are no uprobe events active | |
38 | * at this time. Probably a fine grained per inode count is better? | |
39 | */ | |
40 | #define no_uprobe_events() RB_EMPTY_ROOT(&uprobes_tree) | |
7b2d81d4 | 41 | |
2b144498 SD |
42 | static DEFINE_SPINLOCK(uprobes_treelock); /* serialize rbtree access */ |
43 | ||
44 | #define UPROBES_HASH_SZ 13 | |
2b144498 SD |
45 | /* serialize uprobe->pending_list */ |
46 | static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ]; | |
7b2d81d4 | 47 | #define uprobes_mmap_hash(v) (&uprobes_mmap_mutex[((unsigned long)(v)) % UPROBES_HASH_SZ]) |
2b144498 | 48 | |
32cdba1e ON |
49 | static struct percpu_rw_semaphore dup_mmap_sem; |
50 | ||
cb9a19fe | 51 | /* Have a copy of original instruction */ |
71434f2f | 52 | #define UPROBE_COPY_INSN 0 |
cb9a19fe | 53 | |
3ff54efd SD |
54 | struct uprobe { |
55 | struct rb_node rb_node; /* node in the rb tree */ | |
ce59b8e9 | 56 | refcount_t ref; |
e591c8d7 | 57 | struct rw_semaphore register_rwsem; |
3ff54efd SD |
58 | struct rw_semaphore consumer_rwsem; |
59 | struct list_head pending_list; | |
60 | struct uprobe_consumer *consumers; | |
61 | struct inode *inode; /* Also hold a ref to inode */ | |
62 | loff_t offset; | |
1cc33161 | 63 | loff_t ref_ctr_offset; |
71434f2f | 64 | unsigned long flags; |
ad439356 ON |
65 | |
66 | /* | |
67 | * The generic code assumes that it has two members of unknown type | |
68 | * owned by the arch-specific code: | |
69 | * | |
70 | * insn - copy_insn() saves the original instruction here for | |
71 | * arch_uprobe_analyze_insn(). | |
72 | * | |
73 | * ixol - potentially modified instruction to execute out of | |
74 | * line, copied to xol_area by xol_get_insn_slot(). | |
75 | */ | |
3ff54efd SD |
76 | struct arch_uprobe arch; |
77 | }; | |
78 | ||
1cc33161 RB |
79 | struct delayed_uprobe { |
80 | struct list_head list; | |
81 | struct uprobe *uprobe; | |
82 | struct mm_struct *mm; | |
83 | }; | |
84 | ||
85 | static DEFINE_MUTEX(delayed_uprobe_lock); | |
86 | static LIST_HEAD(delayed_uprobe_list); | |
87 | ||
c912dae6 | 88 | /* |
ad439356 ON |
89 | * Execute out of line area: anonymous executable mapping installed |
90 | * by the probed task to execute the copy of the original instruction | |
91 | * mangled by set_swbp(). | |
92 | * | |
c912dae6 ON |
93 | * On a breakpoint hit, thread contests for a slot. It frees the |
94 | * slot after singlestep. Currently a fixed number of slots are | |
95 | * allocated. | |
96 | */ | |
97 | struct xol_area { | |
704bde3c ON |
98 | wait_queue_head_t wq; /* if all slots are busy */ |
99 | atomic_t slot_count; /* number of in-use slots */ | |
100 | unsigned long *bitmap; /* 0 = free slot */ | |
c912dae6 | 101 | |
704bde3c ON |
102 | struct vm_special_mapping xol_mapping; |
103 | struct page *pages[2]; | |
c912dae6 ON |
104 | /* |
105 | * We keep the vma's vm_start rather than a pointer to the vma | |
106 | * itself. The probed process or a naughty kernel module could make | |
107 | * the vma go away, and we must handle that reasonably gracefully. | |
108 | */ | |
704bde3c | 109 | unsigned long vaddr; /* Page(s) of instruction slots */ |
c912dae6 ON |
110 | }; |
111 | ||
2b144498 SD |
112 | /* |
113 | * valid_vma: Verify if the specified vma is an executable vma | |
114 | * Relax restrictions while unregistering: vm_flags might have | |
115 | * changed after breakpoint was inserted. | |
116 | * - is_register: indicates if we are in register context. | |
117 | * - Return 1 if the specified virtual address is in an | |
118 | * executable vma. | |
119 | */ | |
120 | static bool valid_vma(struct vm_area_struct *vma, bool is_register) | |
121 | { | |
13f59c5e | 122 | vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_MAYSHARE; |
2b144498 | 123 | |
e40cfce6 ON |
124 | if (is_register) |
125 | flags |= VM_WRITE; | |
2b144498 | 126 | |
e40cfce6 | 127 | return vma->vm_file && (vma->vm_flags & flags) == VM_MAYEXEC; |
2b144498 SD |
128 | } |
129 | ||
57683f72 | 130 | static unsigned long offset_to_vaddr(struct vm_area_struct *vma, loff_t offset) |
2b144498 | 131 | { |
57683f72 | 132 | return vma->vm_start + offset - ((loff_t)vma->vm_pgoff << PAGE_SHIFT); |
2b144498 SD |
133 | } |
134 | ||
cb113b47 ON |
135 | static loff_t vaddr_to_offset(struct vm_area_struct *vma, unsigned long vaddr) |
136 | { | |
137 | return ((loff_t)vma->vm_pgoff << PAGE_SHIFT) + (vaddr - vma->vm_start); | |
138 | } | |
139 | ||
2b144498 SD |
140 | /** |
141 | * __replace_page - replace page in vma by new page. | |
142 | * based on replace_page in mm/ksm.c | |
143 | * | |
144 | * @vma: vma that holds the pte pointing to page | |
c517ee74 | 145 | * @addr: address the old @page is mapped at |
2b144498 SD |
146 | * @page: the cowed page we are replacing by kpage |
147 | * @kpage: the modified page we replace page by | |
148 | * | |
149 | * Returns 0 on success, -EFAULT on failure. | |
150 | */ | |
c517ee74 | 151 | static int __replace_page(struct vm_area_struct *vma, unsigned long addr, |
bdfaa2ee | 152 | struct page *old_page, struct page *new_page) |
2b144498 SD |
153 | { |
154 | struct mm_struct *mm = vma->vm_mm; | |
14fa2daa KS |
155 | struct page_vma_mapped_walk pvmw = { |
156 | .page = old_page, | |
157 | .vma = vma, | |
158 | .address = addr, | |
159 | }; | |
9f92448c | 160 | int err; |
ac46d4f3 | 161 | struct mmu_notifier_range range; |
00501b53 JW |
162 | struct mem_cgroup *memcg; |
163 | ||
6f4f13e8 JG |
164 | mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma, mm, addr, |
165 | addr + PAGE_SIZE); | |
ac46d4f3 | 166 | |
14fa2daa KS |
167 | VM_BUG_ON_PAGE(PageTransHuge(old_page), old_page); |
168 | ||
bdfaa2ee | 169 | err = mem_cgroup_try_charge(new_page, vma->vm_mm, GFP_KERNEL, &memcg, |
f627c2f5 | 170 | false); |
00501b53 JW |
171 | if (err) |
172 | return err; | |
2b144498 | 173 | |
194f8dcb | 174 | /* For try_to_free_swap() and munlock_vma_page() below */ |
bdfaa2ee | 175 | lock_page(old_page); |
9f92448c | 176 | |
ac46d4f3 | 177 | mmu_notifier_invalidate_range_start(&range); |
9f92448c | 178 | err = -EAGAIN; |
14fa2daa | 179 | if (!page_vma_mapped_walk(&pvmw)) { |
bdfaa2ee | 180 | mem_cgroup_cancel_charge(new_page, memcg, false); |
9f92448c | 181 | goto unlock; |
6c4687cc | 182 | } |
14fa2daa | 183 | VM_BUG_ON_PAGE(addr != pvmw.address, old_page); |
2b144498 | 184 | |
bdfaa2ee ON |
185 | get_page(new_page); |
186 | page_add_new_anon_rmap(new_page, vma, addr, false); | |
187 | mem_cgroup_commit_charge(new_page, memcg, false, false); | |
188 | lru_cache_add_active_or_unevictable(new_page, vma); | |
2b144498 | 189 | |
bdfaa2ee ON |
190 | if (!PageAnon(old_page)) { |
191 | dec_mm_counter(mm, mm_counter_file(old_page)); | |
7396fa81 SD |
192 | inc_mm_counter(mm, MM_ANONPAGES); |
193 | } | |
194 | ||
14fa2daa KS |
195 | flush_cache_page(vma, addr, pte_pfn(*pvmw.pte)); |
196 | ptep_clear_flush_notify(vma, addr, pvmw.pte); | |
197 | set_pte_at_notify(mm, addr, pvmw.pte, | |
198 | mk_pte(new_page, vma->vm_page_prot)); | |
2b144498 | 199 | |
bdfaa2ee ON |
200 | page_remove_rmap(old_page, false); |
201 | if (!page_mapped(old_page)) | |
202 | try_to_free_swap(old_page); | |
14fa2daa | 203 | page_vma_mapped_walk_done(&pvmw); |
2b144498 | 204 | |
194f8dcb | 205 | if (vma->vm_flags & VM_LOCKED) |
bdfaa2ee ON |
206 | munlock_vma_page(old_page); |
207 | put_page(old_page); | |
194f8dcb | 208 | |
9f92448c ON |
209 | err = 0; |
210 | unlock: | |
ac46d4f3 | 211 | mmu_notifier_invalidate_range_end(&range); |
bdfaa2ee | 212 | unlock_page(old_page); |
9f92448c | 213 | return err; |
2b144498 SD |
214 | } |
215 | ||
216 | /** | |
5cb4ac3a | 217 | * is_swbp_insn - check if instruction is breakpoint instruction. |
2b144498 | 218 | * @insn: instruction to be checked. |
5cb4ac3a | 219 | * Default implementation of is_swbp_insn |
2b144498 SD |
220 | * Returns true if @insn is a breakpoint instruction. |
221 | */ | |
5cb4ac3a | 222 | bool __weak is_swbp_insn(uprobe_opcode_t *insn) |
2b144498 | 223 | { |
5cb4ac3a | 224 | return *insn == UPROBE_SWBP_INSN; |
2b144498 SD |
225 | } |
226 | ||
0908ad6e AM |
227 | /** |
228 | * is_trap_insn - check if instruction is breakpoint instruction. | |
229 | * @insn: instruction to be checked. | |
230 | * Default implementation of is_trap_insn | |
231 | * Returns true if @insn is a breakpoint instruction. | |
232 | * | |
233 | * This function is needed for the case where an architecture has multiple | |
234 | * trap instructions (like powerpc). | |
235 | */ | |
236 | bool __weak is_trap_insn(uprobe_opcode_t *insn) | |
237 | { | |
238 | return is_swbp_insn(insn); | |
239 | } | |
240 | ||
ab0d805c | 241 | static void copy_from_page(struct page *page, unsigned long vaddr, void *dst, int len) |
cceb55aa ON |
242 | { |
243 | void *kaddr = kmap_atomic(page); | |
ab0d805c | 244 | memcpy(dst, kaddr + (vaddr & ~PAGE_MASK), len); |
cceb55aa ON |
245 | kunmap_atomic(kaddr); |
246 | } | |
247 | ||
5669ccee ON |
248 | static void copy_to_page(struct page *page, unsigned long vaddr, const void *src, int len) |
249 | { | |
250 | void *kaddr = kmap_atomic(page); | |
251 | memcpy(kaddr + (vaddr & ~PAGE_MASK), src, len); | |
252 | kunmap_atomic(kaddr); | |
253 | } | |
254 | ||
ed6f6a50 ON |
255 | static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *new_opcode) |
256 | { | |
257 | uprobe_opcode_t old_opcode; | |
258 | bool is_swbp; | |
259 | ||
0908ad6e AM |
260 | /* |
261 | * Note: We only check if the old_opcode is UPROBE_SWBP_INSN here. | |
262 | * We do not check if it is any other 'trap variant' which could | |
263 | * be conditional trap instruction such as the one powerpc supports. | |
264 | * | |
265 | * The logic is that we do not care if the underlying instruction | |
266 | * is a trap variant; uprobes always wins over any other (gdb) | |
267 | * breakpoint. | |
268 | */ | |
ab0d805c | 269 | copy_from_page(page, vaddr, &old_opcode, UPROBE_SWBP_INSN_SIZE); |
ed6f6a50 ON |
270 | is_swbp = is_swbp_insn(&old_opcode); |
271 | ||
272 | if (is_swbp_insn(new_opcode)) { | |
273 | if (is_swbp) /* register: already installed? */ | |
274 | return 0; | |
275 | } else { | |
276 | if (!is_swbp) /* unregister: was it changed by us? */ | |
076a365b | 277 | return 0; |
ed6f6a50 ON |
278 | } |
279 | ||
280 | return 1; | |
281 | } | |
282 | ||
1cc33161 RB |
283 | static struct delayed_uprobe * |
284 | delayed_uprobe_check(struct uprobe *uprobe, struct mm_struct *mm) | |
285 | { | |
286 | struct delayed_uprobe *du; | |
287 | ||
288 | list_for_each_entry(du, &delayed_uprobe_list, list) | |
289 | if (du->uprobe == uprobe && du->mm == mm) | |
290 | return du; | |
291 | return NULL; | |
292 | } | |
293 | ||
294 | static int delayed_uprobe_add(struct uprobe *uprobe, struct mm_struct *mm) | |
295 | { | |
296 | struct delayed_uprobe *du; | |
297 | ||
298 | if (delayed_uprobe_check(uprobe, mm)) | |
299 | return 0; | |
300 | ||
301 | du = kzalloc(sizeof(*du), GFP_KERNEL); | |
302 | if (!du) | |
303 | return -ENOMEM; | |
304 | ||
305 | du->uprobe = uprobe; | |
306 | du->mm = mm; | |
307 | list_add(&du->list, &delayed_uprobe_list); | |
308 | return 0; | |
309 | } | |
310 | ||
311 | static void delayed_uprobe_delete(struct delayed_uprobe *du) | |
312 | { | |
313 | if (WARN_ON(!du)) | |
314 | return; | |
315 | list_del(&du->list); | |
316 | kfree(du); | |
317 | } | |
318 | ||
319 | static void delayed_uprobe_remove(struct uprobe *uprobe, struct mm_struct *mm) | |
320 | { | |
321 | struct list_head *pos, *q; | |
322 | struct delayed_uprobe *du; | |
323 | ||
324 | if (!uprobe && !mm) | |
325 | return; | |
326 | ||
327 | list_for_each_safe(pos, q, &delayed_uprobe_list) { | |
328 | du = list_entry(pos, struct delayed_uprobe, list); | |
329 | ||
330 | if (uprobe && du->uprobe != uprobe) | |
331 | continue; | |
332 | if (mm && du->mm != mm) | |
333 | continue; | |
334 | ||
335 | delayed_uprobe_delete(du); | |
336 | } | |
337 | } | |
338 | ||
339 | static bool valid_ref_ctr_vma(struct uprobe *uprobe, | |
340 | struct vm_area_struct *vma) | |
341 | { | |
342 | unsigned long vaddr = offset_to_vaddr(vma, uprobe->ref_ctr_offset); | |
343 | ||
344 | return uprobe->ref_ctr_offset && | |
345 | vma->vm_file && | |
346 | file_inode(vma->vm_file) == uprobe->inode && | |
347 | (vma->vm_flags & (VM_WRITE|VM_SHARED)) == VM_WRITE && | |
348 | vma->vm_start <= vaddr && | |
349 | vma->vm_end > vaddr; | |
350 | } | |
351 | ||
352 | static struct vm_area_struct * | |
353 | find_ref_ctr_vma(struct uprobe *uprobe, struct mm_struct *mm) | |
354 | { | |
355 | struct vm_area_struct *tmp; | |
356 | ||
357 | for (tmp = mm->mmap; tmp; tmp = tmp->vm_next) | |
358 | if (valid_ref_ctr_vma(uprobe, tmp)) | |
359 | return tmp; | |
360 | ||
361 | return NULL; | |
362 | } | |
363 | ||
364 | static int | |
365 | __update_ref_ctr(struct mm_struct *mm, unsigned long vaddr, short d) | |
366 | { | |
367 | void *kaddr; | |
368 | struct page *page; | |
369 | struct vm_area_struct *vma; | |
370 | int ret; | |
371 | short *ptr; | |
372 | ||
373 | if (!vaddr || !d) | |
374 | return -EINVAL; | |
375 | ||
376 | ret = get_user_pages_remote(NULL, mm, vaddr, 1, | |
377 | FOLL_WRITE, &page, &vma, NULL); | |
378 | if (unlikely(ret <= 0)) { | |
379 | /* | |
380 | * We are asking for 1 page. If get_user_pages_remote() fails, | |
381 | * it may return 0, in that case we have to return error. | |
382 | */ | |
383 | return ret == 0 ? -EBUSY : ret; | |
384 | } | |
385 | ||
386 | kaddr = kmap_atomic(page); | |
387 | ptr = kaddr + (vaddr & ~PAGE_MASK); | |
388 | ||
389 | if (unlikely(*ptr + d < 0)) { | |
390 | pr_warn("ref_ctr going negative. vaddr: 0x%lx, " | |
391 | "curr val: %d, delta: %d\n", vaddr, *ptr, d); | |
392 | ret = -EINVAL; | |
393 | goto out; | |
394 | } | |
395 | ||
396 | *ptr += d; | |
397 | ret = 0; | |
398 | out: | |
399 | kunmap_atomic(kaddr); | |
400 | put_page(page); | |
401 | return ret; | |
402 | } | |
403 | ||
404 | static void update_ref_ctr_warn(struct uprobe *uprobe, | |
405 | struct mm_struct *mm, short d) | |
406 | { | |
407 | pr_warn("ref_ctr %s failed for inode: 0x%lx offset: " | |
408 | "0x%llx ref_ctr_offset: 0x%llx of mm: 0x%pK\n", | |
409 | d > 0 ? "increment" : "decrement", uprobe->inode->i_ino, | |
410 | (unsigned long long) uprobe->offset, | |
411 | (unsigned long long) uprobe->ref_ctr_offset, mm); | |
412 | } | |
413 | ||
414 | static int update_ref_ctr(struct uprobe *uprobe, struct mm_struct *mm, | |
415 | short d) | |
416 | { | |
417 | struct vm_area_struct *rc_vma; | |
418 | unsigned long rc_vaddr; | |
419 | int ret = 0; | |
420 | ||
421 | rc_vma = find_ref_ctr_vma(uprobe, mm); | |
422 | ||
423 | if (rc_vma) { | |
424 | rc_vaddr = offset_to_vaddr(rc_vma, uprobe->ref_ctr_offset); | |
425 | ret = __update_ref_ctr(mm, rc_vaddr, d); | |
426 | if (ret) | |
427 | update_ref_ctr_warn(uprobe, mm, d); | |
428 | ||
429 | if (d > 0) | |
430 | return ret; | |
431 | } | |
432 | ||
433 | mutex_lock(&delayed_uprobe_lock); | |
434 | if (d > 0) | |
435 | ret = delayed_uprobe_add(uprobe, mm); | |
436 | else | |
437 | delayed_uprobe_remove(uprobe, mm); | |
438 | mutex_unlock(&delayed_uprobe_lock); | |
439 | ||
440 | return ret; | |
441 | } | |
442 | ||
2b144498 SD |
443 | /* |
444 | * NOTE: | |
445 | * Expect the breakpoint instruction to be the smallest size instruction for | |
446 | * the architecture. If an arch has variable length instruction and the | |
447 | * breakpoint instruction is not of the smallest length instruction | |
0908ad6e | 448 | * supported by that architecture then we need to modify is_trap_at_addr and |
f72d41fa ON |
449 | * uprobe_write_opcode accordingly. This would never be a problem for archs |
450 | * that have fixed length instructions. | |
29dedee0 | 451 | * |
f72d41fa | 452 | * uprobe_write_opcode - write the opcode at a given virtual address. |
2b144498 | 453 | * @mm: the probed process address space. |
2b144498 SD |
454 | * @vaddr: the virtual address to store the opcode. |
455 | * @opcode: opcode to be written at @vaddr. | |
456 | * | |
29dedee0 | 457 | * Called with mm->mmap_sem held for write. |
2b144498 SD |
458 | * Return 0 (success) or a negative errno. |
459 | */ | |
6d43743e RB |
460 | int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, |
461 | unsigned long vaddr, uprobe_opcode_t opcode) | |
2b144498 | 462 | { |
1cc33161 | 463 | struct uprobe *uprobe; |
2b144498 | 464 | struct page *old_page, *new_page; |
2b144498 | 465 | struct vm_area_struct *vma; |
1cc33161 RB |
466 | int ret, is_register, ref_ctr_updated = 0; |
467 | ||
468 | is_register = is_swbp_insn(&opcode); | |
469 | uprobe = container_of(auprobe, struct uprobe, arch); | |
f403072c | 470 | |
5323ce71 | 471 | retry: |
2b144498 | 472 | /* Read the page with vaddr into memory */ |
c8394812 KS |
473 | ret = get_user_pages_remote(NULL, mm, vaddr, 1, |
474 | FOLL_FORCE | FOLL_SPLIT, &old_page, &vma, NULL); | |
2b144498 SD |
475 | if (ret <= 0) |
476 | return ret; | |
7b2d81d4 | 477 | |
ed6f6a50 ON |
478 | ret = verify_opcode(old_page, vaddr, &opcode); |
479 | if (ret <= 0) | |
480 | goto put_old; | |
481 | ||
1cc33161 RB |
482 | /* We are going to replace instruction, update ref_ctr. */ |
483 | if (!ref_ctr_updated && uprobe->ref_ctr_offset) { | |
484 | ret = update_ref_ctr(uprobe, mm, is_register ? 1 : -1); | |
485 | if (ret) | |
486 | goto put_old; | |
487 | ||
488 | ref_ctr_updated = 1; | |
489 | } | |
490 | ||
29dedee0 ON |
491 | ret = anon_vma_prepare(vma); |
492 | if (ret) | |
493 | goto put_old; | |
494 | ||
2b144498 SD |
495 | ret = -ENOMEM; |
496 | new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr); | |
497 | if (!new_page) | |
9f92448c | 498 | goto put_old; |
2b144498 | 499 | |
29dedee0 | 500 | __SetPageUptodate(new_page); |
3f47107c ON |
501 | copy_highpage(new_page, old_page); |
502 | copy_to_page(new_page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE); | |
2b144498 | 503 | |
c517ee74 | 504 | ret = __replace_page(vma, vaddr, old_page, new_page); |
09cbfeaf | 505 | put_page(new_page); |
9f92448c | 506 | put_old: |
7b2d81d4 IM |
507 | put_page(old_page); |
508 | ||
5323ce71 ON |
509 | if (unlikely(ret == -EAGAIN)) |
510 | goto retry; | |
1cc33161 RB |
511 | |
512 | /* Revert back reference counter if instruction update failed. */ | |
513 | if (ret && is_register && ref_ctr_updated) | |
514 | update_ref_ctr(uprobe, mm, -1); | |
515 | ||
2b144498 SD |
516 | return ret; |
517 | } | |
518 | ||
2b144498 | 519 | /** |
5cb4ac3a | 520 | * set_swbp - store breakpoint at a given address. |
e3343e6a | 521 | * @auprobe: arch specific probepoint information. |
2b144498 | 522 | * @mm: the probed process address space. |
2b144498 SD |
523 | * @vaddr: the virtual address to insert the opcode. |
524 | * | |
525 | * For mm @mm, store the breakpoint instruction at @vaddr. | |
526 | * Return 0 (success) or a negative errno. | |
527 | */ | |
5cb4ac3a | 528 | int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) |
2b144498 | 529 | { |
6d43743e | 530 | return uprobe_write_opcode(auprobe, mm, vaddr, UPROBE_SWBP_INSN); |
2b144498 SD |
531 | } |
532 | ||
533 | /** | |
534 | * set_orig_insn - Restore the original instruction. | |
535 | * @mm: the probed process address space. | |
e3343e6a | 536 | * @auprobe: arch specific probepoint information. |
2b144498 | 537 | * @vaddr: the virtual address to insert the opcode. |
2b144498 SD |
538 | * |
539 | * For mm @mm, restore the original opcode (opcode) at @vaddr. | |
540 | * Return 0 (success) or a negative errno. | |
541 | */ | |
7b2d81d4 | 542 | int __weak |
ded86e7c | 543 | set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) |
2b144498 | 544 | { |
6d43743e RB |
545 | return uprobe_write_opcode(auprobe, mm, vaddr, |
546 | *(uprobe_opcode_t *)&auprobe->insn); | |
2b144498 SD |
547 | } |
548 | ||
f231722a ON |
549 | static struct uprobe *get_uprobe(struct uprobe *uprobe) |
550 | { | |
ce59b8e9 | 551 | refcount_inc(&uprobe->ref); |
f231722a ON |
552 | return uprobe; |
553 | } | |
554 | ||
555 | static void put_uprobe(struct uprobe *uprobe) | |
556 | { | |
ce59b8e9 | 557 | if (refcount_dec_and_test(&uprobe->ref)) { |
1cc33161 RB |
558 | /* |
559 | * If application munmap(exec_vma) before uprobe_unregister() | |
560 | * gets called, we don't get a chance to remove uprobe from | |
561 | * delayed_uprobe_list from remove_breakpoint(). Do it here. | |
562 | */ | |
1aed58e6 | 563 | mutex_lock(&delayed_uprobe_lock); |
1cc33161 | 564 | delayed_uprobe_remove(uprobe, NULL); |
1aed58e6 | 565 | mutex_unlock(&delayed_uprobe_lock); |
f231722a | 566 | kfree(uprobe); |
1cc33161 | 567 | } |
f231722a ON |
568 | } |
569 | ||
2b144498 SD |
570 | static int match_uprobe(struct uprobe *l, struct uprobe *r) |
571 | { | |
572 | if (l->inode < r->inode) | |
573 | return -1; | |
7b2d81d4 | 574 | |
2b144498 SD |
575 | if (l->inode > r->inode) |
576 | return 1; | |
2b144498 | 577 | |
7b2d81d4 IM |
578 | if (l->offset < r->offset) |
579 | return -1; | |
580 | ||
581 | if (l->offset > r->offset) | |
582 | return 1; | |
2b144498 SD |
583 | |
584 | return 0; | |
585 | } | |
586 | ||
587 | static struct uprobe *__find_uprobe(struct inode *inode, loff_t offset) | |
588 | { | |
589 | struct uprobe u = { .inode = inode, .offset = offset }; | |
590 | struct rb_node *n = uprobes_tree.rb_node; | |
591 | struct uprobe *uprobe; | |
592 | int match; | |
593 | ||
594 | while (n) { | |
595 | uprobe = rb_entry(n, struct uprobe, rb_node); | |
596 | match = match_uprobe(&u, uprobe); | |
f231722a ON |
597 | if (!match) |
598 | return get_uprobe(uprobe); | |
7b2d81d4 | 599 | |
2b144498 SD |
600 | if (match < 0) |
601 | n = n->rb_left; | |
602 | else | |
603 | n = n->rb_right; | |
604 | } | |
605 | return NULL; | |
606 | } | |
607 | ||
608 | /* | |
609 | * Find a uprobe corresponding to a given inode:offset | |
610 | * Acquires uprobes_treelock | |
611 | */ | |
612 | static struct uprobe *find_uprobe(struct inode *inode, loff_t offset) | |
613 | { | |
614 | struct uprobe *uprobe; | |
2b144498 | 615 | |
6f47caa0 | 616 | spin_lock(&uprobes_treelock); |
2b144498 | 617 | uprobe = __find_uprobe(inode, offset); |
6f47caa0 | 618 | spin_unlock(&uprobes_treelock); |
7b2d81d4 | 619 | |
2b144498 SD |
620 | return uprobe; |
621 | } | |
622 | ||
623 | static struct uprobe *__insert_uprobe(struct uprobe *uprobe) | |
624 | { | |
625 | struct rb_node **p = &uprobes_tree.rb_node; | |
626 | struct rb_node *parent = NULL; | |
627 | struct uprobe *u; | |
628 | int match; | |
629 | ||
630 | while (*p) { | |
631 | parent = *p; | |
632 | u = rb_entry(parent, struct uprobe, rb_node); | |
633 | match = match_uprobe(uprobe, u); | |
f231722a ON |
634 | if (!match) |
635 | return get_uprobe(u); | |
2b144498 SD |
636 | |
637 | if (match < 0) | |
638 | p = &parent->rb_left; | |
639 | else | |
640 | p = &parent->rb_right; | |
641 | ||
642 | } | |
7b2d81d4 | 643 | |
2b144498 SD |
644 | u = NULL; |
645 | rb_link_node(&uprobe->rb_node, parent, p); | |
646 | rb_insert_color(&uprobe->rb_node, &uprobes_tree); | |
647 | /* get access + creation ref */ | |
ce59b8e9 | 648 | refcount_set(&uprobe->ref, 2); |
7b2d81d4 | 649 | |
2b144498 SD |
650 | return u; |
651 | } | |
652 | ||
653 | /* | |
7b2d81d4 | 654 | * Acquire uprobes_treelock. |
2b144498 SD |
655 | * Matching uprobe already exists in rbtree; |
656 | * increment (access refcount) and return the matching uprobe. | |
657 | * | |
658 | * No matching uprobe; insert the uprobe in rb_tree; | |
659 | * get a double refcount (access + creation) and return NULL. | |
660 | */ | |
661 | static struct uprobe *insert_uprobe(struct uprobe *uprobe) | |
662 | { | |
2b144498 SD |
663 | struct uprobe *u; |
664 | ||
6f47caa0 | 665 | spin_lock(&uprobes_treelock); |
2b144498 | 666 | u = __insert_uprobe(uprobe); |
6f47caa0 | 667 | spin_unlock(&uprobes_treelock); |
7b2d81d4 | 668 | |
2b144498 SD |
669 | return u; |
670 | } | |
671 | ||
22bad382 RB |
672 | static void |
673 | ref_ctr_mismatch_warn(struct uprobe *cur_uprobe, struct uprobe *uprobe) | |
674 | { | |
675 | pr_warn("ref_ctr_offset mismatch. inode: 0x%lx offset: 0x%llx " | |
676 | "ref_ctr_offset(old): 0x%llx ref_ctr_offset(new): 0x%llx\n", | |
677 | uprobe->inode->i_ino, (unsigned long long) uprobe->offset, | |
678 | (unsigned long long) cur_uprobe->ref_ctr_offset, | |
679 | (unsigned long long) uprobe->ref_ctr_offset); | |
680 | } | |
681 | ||
1cc33161 RB |
682 | static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset, |
683 | loff_t ref_ctr_offset) | |
2b144498 SD |
684 | { |
685 | struct uprobe *uprobe, *cur_uprobe; | |
686 | ||
687 | uprobe = kzalloc(sizeof(struct uprobe), GFP_KERNEL); | |
688 | if (!uprobe) | |
689 | return NULL; | |
690 | ||
61f94203 | 691 | uprobe->inode = inode; |
2b144498 | 692 | uprobe->offset = offset; |
1cc33161 | 693 | uprobe->ref_ctr_offset = ref_ctr_offset; |
e591c8d7 | 694 | init_rwsem(&uprobe->register_rwsem); |
2b144498 | 695 | init_rwsem(&uprobe->consumer_rwsem); |
2b144498 SD |
696 | |
697 | /* add to uprobes_tree, sorted on inode:offset */ | |
698 | cur_uprobe = insert_uprobe(uprobe); | |
2b144498 SD |
699 | /* a uprobe exists for this inode:offset combination */ |
700 | if (cur_uprobe) { | |
22bad382 RB |
701 | if (cur_uprobe->ref_ctr_offset != uprobe->ref_ctr_offset) { |
702 | ref_ctr_mismatch_warn(cur_uprobe, uprobe); | |
703 | put_uprobe(cur_uprobe); | |
704 | kfree(uprobe); | |
705 | return ERR_PTR(-EINVAL); | |
706 | } | |
2b144498 SD |
707 | kfree(uprobe); |
708 | uprobe = cur_uprobe; | |
7b2d81d4 IM |
709 | } |
710 | ||
2b144498 SD |
711 | return uprobe; |
712 | } | |
713 | ||
9a98e03c | 714 | static void consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc) |
2b144498 SD |
715 | { |
716 | down_write(&uprobe->consumer_rwsem); | |
e3343e6a SD |
717 | uc->next = uprobe->consumers; |
718 | uprobe->consumers = uc; | |
2b144498 | 719 | up_write(&uprobe->consumer_rwsem); |
2b144498 SD |
720 | } |
721 | ||
722 | /* | |
e3343e6a SD |
723 | * For uprobe @uprobe, delete the consumer @uc. |
724 | * Return true if the @uc is deleted successfully | |
2b144498 SD |
725 | * or return false. |
726 | */ | |
e3343e6a | 727 | static bool consumer_del(struct uprobe *uprobe, struct uprobe_consumer *uc) |
2b144498 SD |
728 | { |
729 | struct uprobe_consumer **con; | |
730 | bool ret = false; | |
731 | ||
732 | down_write(&uprobe->consumer_rwsem); | |
733 | for (con = &uprobe->consumers; *con; con = &(*con)->next) { | |
e3343e6a SD |
734 | if (*con == uc) { |
735 | *con = uc->next; | |
2b144498 SD |
736 | ret = true; |
737 | break; | |
738 | } | |
739 | } | |
740 | up_write(&uprobe->consumer_rwsem); | |
7b2d81d4 | 741 | |
2b144498 SD |
742 | return ret; |
743 | } | |
744 | ||
2ded0980 ON |
745 | static int __copy_insn(struct address_space *mapping, struct file *filp, |
746 | void *insn, int nbytes, loff_t offset) | |
2b144498 | 747 | { |
2b144498 | 748 | struct page *page; |
2b144498 | 749 | /* |
40814f68 ON |
750 | * Ensure that the page that has the original instruction is populated |
751 | * and in page-cache. If ->readpage == NULL it must be shmem_mapping(), | |
752 | * see uprobe_register(). | |
2b144498 | 753 | */ |
40814f68 | 754 | if (mapping->a_ops->readpage) |
09cbfeaf | 755 | page = read_mapping_page(mapping, offset >> PAGE_SHIFT, filp); |
40814f68 | 756 | else |
09cbfeaf | 757 | page = shmem_read_mapping_page(mapping, offset >> PAGE_SHIFT); |
2b144498 SD |
758 | if (IS_ERR(page)) |
759 | return PTR_ERR(page); | |
760 | ||
2edb7b55 | 761 | copy_from_page(page, offset, insn, nbytes); |
09cbfeaf | 762 | put_page(page); |
7b2d81d4 | 763 | |
2b144498 SD |
764 | return 0; |
765 | } | |
766 | ||
d436615e | 767 | static int copy_insn(struct uprobe *uprobe, struct file *filp) |
2b144498 | 768 | { |
2ded0980 ON |
769 | struct address_space *mapping = uprobe->inode->i_mapping; |
770 | loff_t offs = uprobe->offset; | |
803200e2 ON |
771 | void *insn = &uprobe->arch.insn; |
772 | int size = sizeof(uprobe->arch.insn); | |
2ded0980 ON |
773 | int len, err = -EIO; |
774 | ||
775 | /* Copy only available bytes, -EIO if nothing was read */ | |
776 | do { | |
777 | if (offs >= i_size_read(uprobe->inode)) | |
778 | break; | |
779 | ||
780 | len = min_t(int, size, PAGE_SIZE - (offs & ~PAGE_MASK)); | |
781 | err = __copy_insn(mapping, filp, insn, len, offs); | |
fc36f595 | 782 | if (err) |
2ded0980 ON |
783 | break; |
784 | ||
785 | insn += len; | |
786 | offs += len; | |
787 | size -= len; | |
788 | } while (size); | |
789 | ||
790 | return err; | |
2b144498 SD |
791 | } |
792 | ||
cb9a19fe ON |
793 | static int prepare_uprobe(struct uprobe *uprobe, struct file *file, |
794 | struct mm_struct *mm, unsigned long vaddr) | |
795 | { | |
796 | int ret = 0; | |
797 | ||
71434f2f | 798 | if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) |
cb9a19fe ON |
799 | return ret; |
800 | ||
d4d3ccc6 ON |
801 | /* TODO: move this into _register, until then we abuse this sem. */ |
802 | down_write(&uprobe->consumer_rwsem); | |
71434f2f | 803 | if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) |
4710f05f ON |
804 | goto out; |
805 | ||
cb9a19fe ON |
806 | ret = copy_insn(uprobe, file); |
807 | if (ret) | |
808 | goto out; | |
809 | ||
810 | ret = -ENOTSUPP; | |
803200e2 | 811 | if (is_trap_insn((uprobe_opcode_t *)&uprobe->arch.insn)) |
cb9a19fe ON |
812 | goto out; |
813 | ||
814 | ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, vaddr); | |
815 | if (ret) | |
816 | goto out; | |
817 | ||
f72d41fa | 818 | /* uprobe_write_opcode() assumes we don't cross page boundary */ |
cb9a19fe ON |
819 | BUG_ON((uprobe->offset & ~PAGE_MASK) + |
820 | UPROBE_SWBP_INSN_SIZE > PAGE_SIZE); | |
821 | ||
09d3f015 | 822 | smp_wmb(); /* pairs with the smp_rmb() in handle_swbp() */ |
71434f2f | 823 | set_bit(UPROBE_COPY_INSN, &uprobe->flags); |
cb9a19fe ON |
824 | |
825 | out: | |
d4d3ccc6 | 826 | up_write(&uprobe->consumer_rwsem); |
4710f05f | 827 | |
cb9a19fe ON |
828 | return ret; |
829 | } | |
830 | ||
8a7f2fa0 ON |
831 | static inline bool consumer_filter(struct uprobe_consumer *uc, |
832 | enum uprobe_filter_ctx ctx, struct mm_struct *mm) | |
806a98bd | 833 | { |
8a7f2fa0 | 834 | return !uc->filter || uc->filter(uc, ctx, mm); |
806a98bd ON |
835 | } |
836 | ||
8a7f2fa0 ON |
837 | static bool filter_chain(struct uprobe *uprobe, |
838 | enum uprobe_filter_ctx ctx, struct mm_struct *mm) | |
63633cbf | 839 | { |
1ff6fee5 ON |
840 | struct uprobe_consumer *uc; |
841 | bool ret = false; | |
842 | ||
843 | down_read(&uprobe->consumer_rwsem); | |
844 | for (uc = uprobe->consumers; uc; uc = uc->next) { | |
8a7f2fa0 | 845 | ret = consumer_filter(uc, ctx, mm); |
1ff6fee5 ON |
846 | if (ret) |
847 | break; | |
848 | } | |
849 | up_read(&uprobe->consumer_rwsem); | |
850 | ||
851 | return ret; | |
63633cbf ON |
852 | } |
853 | ||
e3343e6a SD |
854 | static int |
855 | install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, | |
816c03fb | 856 | struct vm_area_struct *vma, unsigned long vaddr) |
2b144498 | 857 | { |
f8ac4ec9 | 858 | bool first_uprobe; |
2b144498 SD |
859 | int ret; |
860 | ||
cb9a19fe ON |
861 | ret = prepare_uprobe(uprobe, vma->vm_file, mm, vaddr); |
862 | if (ret) | |
863 | return ret; | |
682968e0 | 864 | |
f8ac4ec9 ON |
865 | /* |
866 | * set MMF_HAS_UPROBES in advance for uprobe_pre_sstep_notifier(), | |
867 | * the task can hit this breakpoint right after __replace_page(). | |
868 | */ | |
869 | first_uprobe = !test_bit(MMF_HAS_UPROBES, &mm->flags); | |
870 | if (first_uprobe) | |
871 | set_bit(MMF_HAS_UPROBES, &mm->flags); | |
872 | ||
816c03fb | 873 | ret = set_swbp(&uprobe->arch, mm, vaddr); |
9f68f672 ON |
874 | if (!ret) |
875 | clear_bit(MMF_RECALC_UPROBES, &mm->flags); | |
876 | else if (first_uprobe) | |
f8ac4ec9 | 877 | clear_bit(MMF_HAS_UPROBES, &mm->flags); |
2b144498 SD |
878 | |
879 | return ret; | |
880 | } | |
881 | ||
076a365b | 882 | static int |
816c03fb | 883 | remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr) |
2b144498 | 884 | { |
9f68f672 | 885 | set_bit(MMF_RECALC_UPROBES, &mm->flags); |
076a365b | 886 | return set_orig_insn(&uprobe->arch, mm, vaddr); |
2b144498 SD |
887 | } |
888 | ||
06b7bcd8 ON |
889 | static inline bool uprobe_is_active(struct uprobe *uprobe) |
890 | { | |
891 | return !RB_EMPTY_NODE(&uprobe->rb_node); | |
892 | } | |
0326f5a9 | 893 | /* |
778b032d ON |
894 | * There could be threads that have already hit the breakpoint. They |
895 | * will recheck the current insn and restart if find_uprobe() fails. | |
896 | * See find_active_uprobe(). | |
0326f5a9 | 897 | */ |
2b144498 SD |
898 | static void delete_uprobe(struct uprobe *uprobe) |
899 | { | |
06b7bcd8 ON |
900 | if (WARN_ON(!uprobe_is_active(uprobe))) |
901 | return; | |
902 | ||
6f47caa0 | 903 | spin_lock(&uprobes_treelock); |
2b144498 | 904 | rb_erase(&uprobe->rb_node, &uprobes_tree); |
6f47caa0 | 905 | spin_unlock(&uprobes_treelock); |
06b7bcd8 | 906 | RB_CLEAR_NODE(&uprobe->rb_node); /* for uprobe_is_active() */ |
2b144498 | 907 | put_uprobe(uprobe); |
2b144498 SD |
908 | } |
909 | ||
26872090 ON |
910 | struct map_info { |
911 | struct map_info *next; | |
912 | struct mm_struct *mm; | |
816c03fb | 913 | unsigned long vaddr; |
26872090 ON |
914 | }; |
915 | ||
916 | static inline struct map_info *free_map_info(struct map_info *info) | |
2b144498 | 917 | { |
26872090 ON |
918 | struct map_info *next = info->next; |
919 | kfree(info); | |
920 | return next; | |
921 | } | |
922 | ||
923 | static struct map_info * | |
924 | build_map_info(struct address_space *mapping, loff_t offset, bool is_register) | |
925 | { | |
926 | unsigned long pgoff = offset >> PAGE_SHIFT; | |
2b144498 | 927 | struct vm_area_struct *vma; |
26872090 ON |
928 | struct map_info *curr = NULL; |
929 | struct map_info *prev = NULL; | |
930 | struct map_info *info; | |
931 | int more = 0; | |
2b144498 | 932 | |
26872090 | 933 | again: |
4a23717a | 934 | i_mmap_lock_read(mapping); |
6b2dbba8 | 935 | vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { |
2b144498 SD |
936 | if (!valid_vma(vma, is_register)) |
937 | continue; | |
938 | ||
7a5bfb66 ON |
939 | if (!prev && !more) { |
940 | /* | |
c8c06efa | 941 | * Needs GFP_NOWAIT to avoid i_mmap_rwsem recursion through |
7a5bfb66 ON |
942 | * reclaim. This is optimistic, no harm done if it fails. |
943 | */ | |
944 | prev = kmalloc(sizeof(struct map_info), | |
945 | GFP_NOWAIT | __GFP_NOMEMALLOC | __GFP_NOWARN); | |
946 | if (prev) | |
947 | prev->next = NULL; | |
948 | } | |
26872090 ON |
949 | if (!prev) { |
950 | more++; | |
951 | continue; | |
2b144498 | 952 | } |
2b144498 | 953 | |
388f7934 | 954 | if (!mmget_not_zero(vma->vm_mm)) |
26872090 | 955 | continue; |
7b2d81d4 | 956 | |
26872090 ON |
957 | info = prev; |
958 | prev = prev->next; | |
959 | info->next = curr; | |
960 | curr = info; | |
2b144498 | 961 | |
26872090 | 962 | info->mm = vma->vm_mm; |
57683f72 | 963 | info->vaddr = offset_to_vaddr(vma, offset); |
26872090 | 964 | } |
4a23717a | 965 | i_mmap_unlock_read(mapping); |
2b144498 | 966 | |
26872090 ON |
967 | if (!more) |
968 | goto out; | |
969 | ||
970 | prev = curr; | |
971 | while (curr) { | |
972 | mmput(curr->mm); | |
973 | curr = curr->next; | |
974 | } | |
7b2d81d4 | 975 | |
26872090 ON |
976 | do { |
977 | info = kmalloc(sizeof(struct map_info), GFP_KERNEL); | |
978 | if (!info) { | |
979 | curr = ERR_PTR(-ENOMEM); | |
980 | goto out; | |
981 | } | |
982 | info->next = prev; | |
983 | prev = info; | |
984 | } while (--more); | |
985 | ||
986 | goto again; | |
987 | out: | |
988 | while (prev) | |
989 | prev = free_map_info(prev); | |
990 | return curr; | |
2b144498 SD |
991 | } |
992 | ||
bdf8647c ON |
993 | static int |
994 | register_for_each_vma(struct uprobe *uprobe, struct uprobe_consumer *new) | |
2b144498 | 995 | { |
bdf8647c | 996 | bool is_register = !!new; |
26872090 ON |
997 | struct map_info *info; |
998 | int err = 0; | |
2b144498 | 999 | |
32cdba1e | 1000 | percpu_down_write(&dup_mmap_sem); |
26872090 ON |
1001 | info = build_map_info(uprobe->inode->i_mapping, |
1002 | uprobe->offset, is_register); | |
32cdba1e ON |
1003 | if (IS_ERR(info)) { |
1004 | err = PTR_ERR(info); | |
1005 | goto out; | |
1006 | } | |
7b2d81d4 | 1007 | |
26872090 ON |
1008 | while (info) { |
1009 | struct mm_struct *mm = info->mm; | |
1010 | struct vm_area_struct *vma; | |
7b2d81d4 | 1011 | |
076a365b | 1012 | if (err && is_register) |
26872090 | 1013 | goto free; |
7b2d81d4 | 1014 | |
77fc4af1 | 1015 | down_write(&mm->mmap_sem); |
f4d6dfe5 ON |
1016 | vma = find_vma(mm, info->vaddr); |
1017 | if (!vma || !valid_vma(vma, is_register) || | |
f281769e | 1018 | file_inode(vma->vm_file) != uprobe->inode) |
26872090 ON |
1019 | goto unlock; |
1020 | ||
f4d6dfe5 ON |
1021 | if (vma->vm_start > info->vaddr || |
1022 | vaddr_to_offset(vma, info->vaddr) != uprobe->offset) | |
26872090 | 1023 | goto unlock; |
2b144498 | 1024 | |
806a98bd ON |
1025 | if (is_register) { |
1026 | /* consult only the "caller", new consumer. */ | |
bdf8647c | 1027 | if (consumer_filter(new, |
8a7f2fa0 | 1028 | UPROBE_FILTER_REGISTER, mm)) |
806a98bd ON |
1029 | err = install_breakpoint(uprobe, mm, vma, info->vaddr); |
1030 | } else if (test_bit(MMF_HAS_UPROBES, &mm->flags)) { | |
8a7f2fa0 ON |
1031 | if (!filter_chain(uprobe, |
1032 | UPROBE_FILTER_UNREGISTER, mm)) | |
806a98bd ON |
1033 | err |= remove_breakpoint(uprobe, mm, info->vaddr); |
1034 | } | |
78f74116 | 1035 | |
26872090 ON |
1036 | unlock: |
1037 | up_write(&mm->mmap_sem); | |
1038 | free: | |
1039 | mmput(mm); | |
1040 | info = free_map_info(info); | |
2b144498 | 1041 | } |
32cdba1e ON |
1042 | out: |
1043 | percpu_up_write(&dup_mmap_sem); | |
26872090 | 1044 | return err; |
2b144498 SD |
1045 | } |
1046 | ||
38e967ae RB |
1047 | static void |
1048 | __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc) | |
2b144498 | 1049 | { |
04aab9b2 ON |
1050 | int err; |
1051 | ||
06d07139 | 1052 | if (WARN_ON(!consumer_del(uprobe, uc))) |
04aab9b2 | 1053 | return; |
2b144498 | 1054 | |
bdf8647c | 1055 | err = register_for_each_vma(uprobe, NULL); |
bb929284 ON |
1056 | /* TODO : cant unregister? schedule a worker thread */ |
1057 | if (!uprobe->consumers && !err) | |
1058 | delete_uprobe(uprobe); | |
2b144498 SD |
1059 | } |
1060 | ||
1061 | /* | |
7140ad38 | 1062 | * uprobe_unregister - unregister an already registered probe. |
38e967ae RB |
1063 | * @inode: the file in which the probe has to be removed. |
1064 | * @offset: offset from the start of the file. | |
1065 | * @uc: identify which probe if multiple probes are colocated. | |
1066 | */ | |
1067 | void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) | |
1068 | { | |
1069 | struct uprobe *uprobe; | |
1070 | ||
1071 | uprobe = find_uprobe(inode, offset); | |
1072 | if (WARN_ON(!uprobe)) | |
1073 | return; | |
1074 | ||
1075 | down_write(&uprobe->register_rwsem); | |
1076 | __uprobe_unregister(uprobe, uc); | |
1077 | up_write(&uprobe->register_rwsem); | |
1078 | put_uprobe(uprobe); | |
1079 | } | |
1080 | EXPORT_SYMBOL_GPL(uprobe_unregister); | |
1081 | ||
1082 | /* | |
1083 | * __uprobe_register - register a probe | |
2b144498 SD |
1084 | * @inode: the file in which the probe has to be placed. |
1085 | * @offset: offset from the start of the file. | |
e3343e6a | 1086 | * @uc: information on howto handle the probe.. |
2b144498 | 1087 | * |
38e967ae | 1088 | * Apart from the access refcount, __uprobe_register() takes a creation |
2b144498 SD |
1089 | * refcount (thro alloc_uprobe) if and only if this @uprobe is getting |
1090 | * inserted into the rbtree (i.e first consumer for a @inode:@offset | |
7b2d81d4 | 1091 | * tuple). Creation refcount stops uprobe_unregister from freeing the |
2b144498 | 1092 | * @uprobe even before the register operation is complete. Creation |
e3343e6a | 1093 | * refcount is released when the last @uc for the @uprobe |
38e967ae | 1094 | * unregisters. Caller of __uprobe_register() is required to keep @inode |
61f94203 | 1095 | * (and the containing mount) referenced. |
2b144498 SD |
1096 | * |
1097 | * Return errno if it cannot successully install probes | |
1098 | * else return 0 (success) | |
1099 | */ | |
38e967ae | 1100 | static int __uprobe_register(struct inode *inode, loff_t offset, |
1cc33161 | 1101 | loff_t ref_ctr_offset, struct uprobe_consumer *uc) |
2b144498 SD |
1102 | { |
1103 | struct uprobe *uprobe; | |
7b2d81d4 | 1104 | int ret; |
2b144498 | 1105 | |
ea024870 AA |
1106 | /* Uprobe must have at least one set consumer */ |
1107 | if (!uc->handler && !uc->ret_handler) | |
1108 | return -EINVAL; | |
1109 | ||
40814f68 ON |
1110 | /* copy_insn() uses read_mapping_page() or shmem_read_mapping_page() */ |
1111 | if (!inode->i_mapping->a_ops->readpage && !shmem_mapping(inode->i_mapping)) | |
41ccba02 | 1112 | return -EIO; |
f0744af7 | 1113 | /* Racy, just to catch the obvious mistakes */ |
2b144498 | 1114 | if (offset > i_size_read(inode)) |
7b2d81d4 | 1115 | return -EINVAL; |
2b144498 | 1116 | |
66d06dff | 1117 | retry: |
1cc33161 | 1118 | uprobe = alloc_uprobe(inode, offset, ref_ctr_offset); |
66d06dff ON |
1119 | if (!uprobe) |
1120 | return -ENOMEM; | |
22bad382 RB |
1121 | if (IS_ERR(uprobe)) |
1122 | return PTR_ERR(uprobe); | |
1123 | ||
66d06dff ON |
1124 | /* |
1125 | * We can race with uprobe_unregister()->delete_uprobe(). | |
1126 | * Check uprobe_is_active() and retry if it is false. | |
1127 | */ | |
1128 | down_write(&uprobe->register_rwsem); | |
1129 | ret = -EAGAIN; | |
1130 | if (likely(uprobe_is_active(uprobe))) { | |
38e967ae RB |
1131 | consumer_add(uprobe, uc); |
1132 | ret = register_for_each_vma(uprobe, uc); | |
9a98e03c | 1133 | if (ret) |
04aab9b2 | 1134 | __uprobe_unregister(uprobe, uc); |
2b144498 | 1135 | } |
66d06dff ON |
1136 | up_write(&uprobe->register_rwsem); |
1137 | put_uprobe(uprobe); | |
2b144498 | 1138 | |
66d06dff ON |
1139 | if (unlikely(ret == -EAGAIN)) |
1140 | goto retry; | |
2b144498 SD |
1141 | return ret; |
1142 | } | |
38e967ae RB |
1143 | |
1144 | int uprobe_register(struct inode *inode, loff_t offset, | |
1145 | struct uprobe_consumer *uc) | |
1146 | { | |
1cc33161 | 1147 | return __uprobe_register(inode, offset, 0, uc); |
38e967ae | 1148 | } |
e8440c14 | 1149 | EXPORT_SYMBOL_GPL(uprobe_register); |
2b144498 | 1150 | |
1cc33161 RB |
1151 | int uprobe_register_refctr(struct inode *inode, loff_t offset, |
1152 | loff_t ref_ctr_offset, struct uprobe_consumer *uc) | |
1153 | { | |
1154 | return __uprobe_register(inode, offset, ref_ctr_offset, uc); | |
1155 | } | |
1156 | EXPORT_SYMBOL_GPL(uprobe_register_refctr); | |
1157 | ||
bdf8647c | 1158 | /* |
788faab7 | 1159 | * uprobe_apply - unregister an already registered probe. |
bdf8647c ON |
1160 | * @inode: the file in which the probe has to be removed. |
1161 | * @offset: offset from the start of the file. | |
1162 | * @uc: consumer which wants to add more or remove some breakpoints | |
1163 | * @add: add or remove the breakpoints | |
1164 | */ | |
1165 | int uprobe_apply(struct inode *inode, loff_t offset, | |
1166 | struct uprobe_consumer *uc, bool add) | |
1167 | { | |
1168 | struct uprobe *uprobe; | |
1169 | struct uprobe_consumer *con; | |
1170 | int ret = -ENOENT; | |
1171 | ||
1172 | uprobe = find_uprobe(inode, offset); | |
06d07139 | 1173 | if (WARN_ON(!uprobe)) |
bdf8647c ON |
1174 | return ret; |
1175 | ||
1176 | down_write(&uprobe->register_rwsem); | |
1177 | for (con = uprobe->consumers; con && con != uc ; con = con->next) | |
1178 | ; | |
1179 | if (con) | |
1180 | ret = register_for_each_vma(uprobe, add ? uc : NULL); | |
1181 | up_write(&uprobe->register_rwsem); | |
1182 | put_uprobe(uprobe); | |
1183 | ||
1184 | return ret; | |
1185 | } | |
1186 | ||
da1816b1 ON |
1187 | static int unapply_uprobe(struct uprobe *uprobe, struct mm_struct *mm) |
1188 | { | |
1189 | struct vm_area_struct *vma; | |
1190 | int err = 0; | |
1191 | ||
1192 | down_read(&mm->mmap_sem); | |
1193 | for (vma = mm->mmap; vma; vma = vma->vm_next) { | |
1194 | unsigned long vaddr; | |
1195 | loff_t offset; | |
1196 | ||
1197 | if (!valid_vma(vma, false) || | |
f281769e | 1198 | file_inode(vma->vm_file) != uprobe->inode) |
da1816b1 ON |
1199 | continue; |
1200 | ||
1201 | offset = (loff_t)vma->vm_pgoff << PAGE_SHIFT; | |
1202 | if (uprobe->offset < offset || | |
1203 | uprobe->offset >= offset + vma->vm_end - vma->vm_start) | |
1204 | continue; | |
1205 | ||
1206 | vaddr = offset_to_vaddr(vma, uprobe->offset); | |
1207 | err |= remove_breakpoint(uprobe, mm, vaddr); | |
1208 | } | |
1209 | up_read(&mm->mmap_sem); | |
1210 | ||
1211 | return err; | |
1212 | } | |
1213 | ||
891c3970 ON |
1214 | static struct rb_node * |
1215 | find_node_in_range(struct inode *inode, loff_t min, loff_t max) | |
2b144498 | 1216 | { |
2b144498 | 1217 | struct rb_node *n = uprobes_tree.rb_node; |
2b144498 SD |
1218 | |
1219 | while (n) { | |
891c3970 | 1220 | struct uprobe *u = rb_entry(n, struct uprobe, rb_node); |
2b144498 | 1221 | |
891c3970 | 1222 | if (inode < u->inode) { |
2b144498 | 1223 | n = n->rb_left; |
891c3970 | 1224 | } else if (inode > u->inode) { |
2b144498 | 1225 | n = n->rb_right; |
891c3970 ON |
1226 | } else { |
1227 | if (max < u->offset) | |
1228 | n = n->rb_left; | |
1229 | else if (min > u->offset) | |
1230 | n = n->rb_right; | |
1231 | else | |
1232 | break; | |
1233 | } | |
2b144498 | 1234 | } |
7b2d81d4 | 1235 | |
891c3970 | 1236 | return n; |
2b144498 SD |
1237 | } |
1238 | ||
1239 | /* | |
891c3970 | 1240 | * For a given range in vma, build a list of probes that need to be inserted. |
2b144498 | 1241 | */ |
891c3970 ON |
1242 | static void build_probe_list(struct inode *inode, |
1243 | struct vm_area_struct *vma, | |
1244 | unsigned long start, unsigned long end, | |
1245 | struct list_head *head) | |
2b144498 | 1246 | { |
891c3970 | 1247 | loff_t min, max; |
891c3970 ON |
1248 | struct rb_node *n, *t; |
1249 | struct uprobe *u; | |
7b2d81d4 | 1250 | |
891c3970 | 1251 | INIT_LIST_HEAD(head); |
cb113b47 | 1252 | min = vaddr_to_offset(vma, start); |
891c3970 | 1253 | max = min + (end - start) - 1; |
2b144498 | 1254 | |
6f47caa0 | 1255 | spin_lock(&uprobes_treelock); |
891c3970 ON |
1256 | n = find_node_in_range(inode, min, max); |
1257 | if (n) { | |
1258 | for (t = n; t; t = rb_prev(t)) { | |
1259 | u = rb_entry(t, struct uprobe, rb_node); | |
1260 | if (u->inode != inode || u->offset < min) | |
1261 | break; | |
1262 | list_add(&u->pending_list, head); | |
f231722a | 1263 | get_uprobe(u); |
891c3970 ON |
1264 | } |
1265 | for (t = n; (t = rb_next(t)); ) { | |
1266 | u = rb_entry(t, struct uprobe, rb_node); | |
1267 | if (u->inode != inode || u->offset > max) | |
1268 | break; | |
1269 | list_add(&u->pending_list, head); | |
f231722a | 1270 | get_uprobe(u); |
891c3970 | 1271 | } |
2b144498 | 1272 | } |
6f47caa0 | 1273 | spin_unlock(&uprobes_treelock); |
2b144498 SD |
1274 | } |
1275 | ||
1cc33161 RB |
1276 | /* @vma contains reference counter, not the probed instruction. */ |
1277 | static int delayed_ref_ctr_inc(struct vm_area_struct *vma) | |
1278 | { | |
1279 | struct list_head *pos, *q; | |
1280 | struct delayed_uprobe *du; | |
1281 | unsigned long vaddr; | |
1282 | int ret = 0, err = 0; | |
1283 | ||
1284 | mutex_lock(&delayed_uprobe_lock); | |
1285 | list_for_each_safe(pos, q, &delayed_uprobe_list) { | |
1286 | du = list_entry(pos, struct delayed_uprobe, list); | |
1287 | ||
1288 | if (du->mm != vma->vm_mm || | |
1289 | !valid_ref_ctr_vma(du->uprobe, vma)) | |
1290 | continue; | |
1291 | ||
1292 | vaddr = offset_to_vaddr(vma, du->uprobe->ref_ctr_offset); | |
1293 | ret = __update_ref_ctr(vma->vm_mm, vaddr, 1); | |
1294 | if (ret) { | |
1295 | update_ref_ctr_warn(du->uprobe, vma->vm_mm, 1); | |
1296 | if (!err) | |
1297 | err = ret; | |
1298 | } | |
1299 | delayed_uprobe_delete(du); | |
1300 | } | |
1301 | mutex_unlock(&delayed_uprobe_lock); | |
1302 | return err; | |
1303 | } | |
1304 | ||
2b144498 | 1305 | /* |
5e5be71a | 1306 | * Called from mmap_region/vma_adjust with mm->mmap_sem acquired. |
2b144498 | 1307 | * |
5e5be71a ON |
1308 | * Currently we ignore all errors and always return 0, the callers |
1309 | * can't handle the failure anyway. | |
2b144498 | 1310 | */ |
7b2d81d4 | 1311 | int uprobe_mmap(struct vm_area_struct *vma) |
2b144498 SD |
1312 | { |
1313 | struct list_head tmp_list; | |
665605a2 | 1314 | struct uprobe *uprobe, *u; |
2b144498 | 1315 | struct inode *inode; |
2b144498 | 1316 | |
1cc33161 RB |
1317 | if (no_uprobe_events()) |
1318 | return 0; | |
1319 | ||
1320 | if (vma->vm_file && | |
1321 | (vma->vm_flags & (VM_WRITE|VM_SHARED)) == VM_WRITE && | |
1322 | test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags)) | |
1323 | delayed_ref_ctr_inc(vma); | |
1324 | ||
1325 | if (!valid_vma(vma, true)) | |
7b2d81d4 | 1326 | return 0; |
2b144498 | 1327 | |
f281769e | 1328 | inode = file_inode(vma->vm_file); |
2b144498 | 1329 | if (!inode) |
7b2d81d4 | 1330 | return 0; |
2b144498 | 1331 | |
2b144498 | 1332 | mutex_lock(uprobes_mmap_hash(inode)); |
891c3970 | 1333 | build_probe_list(inode, vma, vma->vm_start, vma->vm_end, &tmp_list); |
806a98bd ON |
1334 | /* |
1335 | * We can race with uprobe_unregister(), this uprobe can be already | |
1336 | * removed. But in this case filter_chain() must return false, all | |
1337 | * consumers have gone away. | |
1338 | */ | |
665605a2 | 1339 | list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) { |
806a98bd | 1340 | if (!fatal_signal_pending(current) && |
8a7f2fa0 | 1341 | filter_chain(uprobe, UPROBE_FILTER_MMAP, vma->vm_mm)) { |
57683f72 | 1342 | unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset); |
5e5be71a | 1343 | install_breakpoint(uprobe, vma->vm_mm, vma, vaddr); |
2b144498 SD |
1344 | } |
1345 | put_uprobe(uprobe); | |
1346 | } | |
2b144498 SD |
1347 | mutex_unlock(uprobes_mmap_hash(inode)); |
1348 | ||
5e5be71a | 1349 | return 0; |
2b144498 SD |
1350 | } |
1351 | ||
9f68f672 ON |
1352 | static bool |
1353 | vma_has_uprobes(struct vm_area_struct *vma, unsigned long start, unsigned long end) | |
1354 | { | |
1355 | loff_t min, max; | |
1356 | struct inode *inode; | |
1357 | struct rb_node *n; | |
1358 | ||
f281769e | 1359 | inode = file_inode(vma->vm_file); |
9f68f672 ON |
1360 | |
1361 | min = vaddr_to_offset(vma, start); | |
1362 | max = min + (end - start) - 1; | |
1363 | ||
1364 | spin_lock(&uprobes_treelock); | |
1365 | n = find_node_in_range(inode, min, max); | |
1366 | spin_unlock(&uprobes_treelock); | |
1367 | ||
1368 | return !!n; | |
1369 | } | |
1370 | ||
682968e0 SD |
1371 | /* |
1372 | * Called in context of a munmap of a vma. | |
1373 | */ | |
cbc91f71 | 1374 | void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end) |
682968e0 | 1375 | { |
441f1eb7 | 1376 | if (no_uprobe_events() || !valid_vma(vma, false)) |
682968e0 SD |
1377 | return; |
1378 | ||
2fd611a9 ON |
1379 | if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */ |
1380 | return; | |
1381 | ||
9f68f672 ON |
1382 | if (!test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags) || |
1383 | test_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags)) | |
f8ac4ec9 ON |
1384 | return; |
1385 | ||
9f68f672 ON |
1386 | if (vma_has_uprobes(vma, start, end)) |
1387 | set_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags); | |
682968e0 SD |
1388 | } |
1389 | ||
d4b3b638 | 1390 | /* Slot allocation for XOL */ |
6441ec8b | 1391 | static int xol_add_vma(struct mm_struct *mm, struct xol_area *area) |
d4b3b638 | 1392 | { |
704bde3c ON |
1393 | struct vm_area_struct *vma; |
1394 | int ret; | |
d4b3b638 | 1395 | |
598fdc1d MH |
1396 | if (down_write_killable(&mm->mmap_sem)) |
1397 | return -EINTR; | |
1398 | ||
704bde3c ON |
1399 | if (mm->uprobes_state.xol_area) { |
1400 | ret = -EALREADY; | |
d4b3b638 | 1401 | goto fail; |
704bde3c | 1402 | } |
d4b3b638 | 1403 | |
af0d95af ON |
1404 | if (!area->vaddr) { |
1405 | /* Try to map as high as possible, this is only a hint. */ | |
1406 | area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE, | |
1407 | PAGE_SIZE, 0, 0); | |
1408 | if (area->vaddr & ~PAGE_MASK) { | |
1409 | ret = area->vaddr; | |
1410 | goto fail; | |
1411 | } | |
d4b3b638 SD |
1412 | } |
1413 | ||
704bde3c ON |
1414 | vma = _install_special_mapping(mm, area->vaddr, PAGE_SIZE, |
1415 | VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO, | |
1416 | &area->xol_mapping); | |
1417 | if (IS_ERR(vma)) { | |
1418 | ret = PTR_ERR(vma); | |
d4b3b638 | 1419 | goto fail; |
704bde3c | 1420 | } |
d4b3b638 | 1421 | |
704bde3c | 1422 | ret = 0; |
5c6338b4 PM |
1423 | /* pairs with get_xol_area() */ |
1424 | smp_store_release(&mm->uprobes_state.xol_area, area); /* ^^^ */ | |
c8a82538 | 1425 | fail: |
d4b3b638 | 1426 | up_write(&mm->mmap_sem); |
d4b3b638 SD |
1427 | |
1428 | return ret; | |
1429 | } | |
1430 | ||
af0d95af | 1431 | static struct xol_area *__create_xol_area(unsigned long vaddr) |
d4b3b638 | 1432 | { |
9b545df8 | 1433 | struct mm_struct *mm = current->mm; |
e78aebfd | 1434 | uprobe_opcode_t insn = UPROBE_SWBP_INSN; |
6441ec8b | 1435 | struct xol_area *area; |
9b545df8 | 1436 | |
af0d95af | 1437 | area = kmalloc(sizeof(*area), GFP_KERNEL); |
d4b3b638 | 1438 | if (unlikely(!area)) |
c8a82538 | 1439 | goto out; |
d4b3b638 | 1440 | |
6396bb22 KC |
1441 | area->bitmap = kcalloc(BITS_TO_LONGS(UINSNS_PER_PAGE), sizeof(long), |
1442 | GFP_KERNEL); | |
d4b3b638 | 1443 | if (!area->bitmap) |
c8a82538 ON |
1444 | goto free_area; |
1445 | ||
704bde3c | 1446 | area->xol_mapping.name = "[uprobes]"; |
869ae761 | 1447 | area->xol_mapping.fault = NULL; |
704bde3c | 1448 | area->xol_mapping.pages = area->pages; |
f58bea2f ON |
1449 | area->pages[0] = alloc_page(GFP_HIGHUSER); |
1450 | if (!area->pages[0]) | |
c8a82538 | 1451 | goto free_bitmap; |
f58bea2f | 1452 | area->pages[1] = NULL; |
d4b3b638 | 1453 | |
af0d95af | 1454 | area->vaddr = vaddr; |
6441ec8b ON |
1455 | init_waitqueue_head(&area->wq); |
1456 | /* Reserve the 1st slot for get_trampoline_vaddr() */ | |
e78aebfd | 1457 | set_bit(0, area->bitmap); |
e78aebfd | 1458 | atomic_set(&area->slot_count, 1); |
297e765e | 1459 | arch_uprobe_copy_ixol(area->pages[0], 0, &insn, UPROBE_SWBP_INSN_SIZE); |
e78aebfd | 1460 | |
6441ec8b | 1461 | if (!xol_add_vma(mm, area)) |
d4b3b638 SD |
1462 | return area; |
1463 | ||
f58bea2f | 1464 | __free_page(area->pages[0]); |
c8a82538 | 1465 | free_bitmap: |
d4b3b638 | 1466 | kfree(area->bitmap); |
c8a82538 | 1467 | free_area: |
d4b3b638 | 1468 | kfree(area); |
c8a82538 | 1469 | out: |
6441ec8b ON |
1470 | return NULL; |
1471 | } | |
1472 | ||
1473 | /* | |
1474 | * get_xol_area - Allocate process's xol_area if necessary. | |
1475 | * This area will be used for storing instructions for execution out of line. | |
1476 | * | |
1477 | * Returns the allocated area or NULL. | |
1478 | */ | |
1479 | static struct xol_area *get_xol_area(void) | |
1480 | { | |
1481 | struct mm_struct *mm = current->mm; | |
1482 | struct xol_area *area; | |
1483 | ||
1484 | if (!mm->uprobes_state.xol_area) | |
af0d95af | 1485 | __create_xol_area(0); |
6441ec8b | 1486 | |
5c6338b4 PM |
1487 | /* Pairs with xol_add_vma() smp_store_release() */ |
1488 | area = READ_ONCE(mm->uprobes_state.xol_area); /* ^^^ */ | |
9b545df8 | 1489 | return area; |
d4b3b638 SD |
1490 | } |
1491 | ||
1492 | /* | |
1493 | * uprobe_clear_state - Free the area allocated for slots. | |
1494 | */ | |
1495 | void uprobe_clear_state(struct mm_struct *mm) | |
1496 | { | |
1497 | struct xol_area *area = mm->uprobes_state.xol_area; | |
1498 | ||
1cc33161 RB |
1499 | mutex_lock(&delayed_uprobe_lock); |
1500 | delayed_uprobe_remove(NULL, mm); | |
1501 | mutex_unlock(&delayed_uprobe_lock); | |
1502 | ||
d4b3b638 SD |
1503 | if (!area) |
1504 | return; | |
1505 | ||
f58bea2f | 1506 | put_page(area->pages[0]); |
d4b3b638 SD |
1507 | kfree(area->bitmap); |
1508 | kfree(area); | |
1509 | } | |
1510 | ||
32cdba1e ON |
1511 | void uprobe_start_dup_mmap(void) |
1512 | { | |
1513 | percpu_down_read(&dup_mmap_sem); | |
1514 | } | |
1515 | ||
1516 | void uprobe_end_dup_mmap(void) | |
1517 | { | |
1518 | percpu_up_read(&dup_mmap_sem); | |
1519 | } | |
1520 | ||
f8ac4ec9 ON |
1521 | void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm) |
1522 | { | |
9f68f672 | 1523 | if (test_bit(MMF_HAS_UPROBES, &oldmm->flags)) { |
f8ac4ec9 | 1524 | set_bit(MMF_HAS_UPROBES, &newmm->flags); |
9f68f672 ON |
1525 | /* unconditionally, dup_mmap() skips VM_DONTCOPY vmas */ |
1526 | set_bit(MMF_RECALC_UPROBES, &newmm->flags); | |
1527 | } | |
f8ac4ec9 ON |
1528 | } |
1529 | ||
d4b3b638 SD |
1530 | /* |
1531 | * - search for a free slot. | |
1532 | */ | |
1533 | static unsigned long xol_take_insn_slot(struct xol_area *area) | |
1534 | { | |
1535 | unsigned long slot_addr; | |
1536 | int slot_nr; | |
1537 | ||
1538 | do { | |
1539 | slot_nr = find_first_zero_bit(area->bitmap, UINSNS_PER_PAGE); | |
1540 | if (slot_nr < UINSNS_PER_PAGE) { | |
1541 | if (!test_and_set_bit(slot_nr, area->bitmap)) | |
1542 | break; | |
1543 | ||
1544 | slot_nr = UINSNS_PER_PAGE; | |
1545 | continue; | |
1546 | } | |
1547 | wait_event(area->wq, (atomic_read(&area->slot_count) < UINSNS_PER_PAGE)); | |
1548 | } while (slot_nr >= UINSNS_PER_PAGE); | |
1549 | ||
1550 | slot_addr = area->vaddr + (slot_nr * UPROBE_XOL_SLOT_BYTES); | |
1551 | atomic_inc(&area->slot_count); | |
1552 | ||
1553 | return slot_addr; | |
1554 | } | |
1555 | ||
1556 | /* | |
a6cb3f6d | 1557 | * xol_get_insn_slot - allocate a slot for xol. |
d4b3b638 SD |
1558 | * Returns the allocated slot address or 0. |
1559 | */ | |
a6cb3f6d | 1560 | static unsigned long xol_get_insn_slot(struct uprobe *uprobe) |
d4b3b638 SD |
1561 | { |
1562 | struct xol_area *area; | |
a6cb3f6d | 1563 | unsigned long xol_vaddr; |
d4b3b638 | 1564 | |
9b545df8 ON |
1565 | area = get_xol_area(); |
1566 | if (!area) | |
1567 | return 0; | |
d4b3b638 | 1568 | |
a6cb3f6d ON |
1569 | xol_vaddr = xol_take_insn_slot(area); |
1570 | if (unlikely(!xol_vaddr)) | |
d4b3b638 SD |
1571 | return 0; |
1572 | ||
f58bea2f | 1573 | arch_uprobe_copy_ixol(area->pages[0], xol_vaddr, |
72e6ae28 | 1574 | &uprobe->arch.ixol, sizeof(uprobe->arch.ixol)); |
d4b3b638 | 1575 | |
a6cb3f6d | 1576 | return xol_vaddr; |
d4b3b638 SD |
1577 | } |
1578 | ||
1579 | /* | |
1580 | * xol_free_insn_slot - If slot was earlier allocated by | |
1581 | * @xol_get_insn_slot(), make the slot available for | |
1582 | * subsequent requests. | |
1583 | */ | |
1584 | static void xol_free_insn_slot(struct task_struct *tsk) | |
1585 | { | |
1586 | struct xol_area *area; | |
1587 | unsigned long vma_end; | |
1588 | unsigned long slot_addr; | |
1589 | ||
1590 | if (!tsk->mm || !tsk->mm->uprobes_state.xol_area || !tsk->utask) | |
1591 | return; | |
1592 | ||
1593 | slot_addr = tsk->utask->xol_vaddr; | |
af4355e9 | 1594 | if (unlikely(!slot_addr)) |
d4b3b638 SD |
1595 | return; |
1596 | ||
1597 | area = tsk->mm->uprobes_state.xol_area; | |
1598 | vma_end = area->vaddr + PAGE_SIZE; | |
1599 | if (area->vaddr <= slot_addr && slot_addr < vma_end) { | |
1600 | unsigned long offset; | |
1601 | int slot_nr; | |
1602 | ||
1603 | offset = slot_addr - area->vaddr; | |
1604 | slot_nr = offset / UPROBE_XOL_SLOT_BYTES; | |
1605 | if (slot_nr >= UINSNS_PER_PAGE) | |
1606 | return; | |
1607 | ||
1608 | clear_bit(slot_nr, area->bitmap); | |
1609 | atomic_dec(&area->slot_count); | |
2a742ced | 1610 | smp_mb__after_atomic(); /* pairs with prepare_to_wait() */ |
d4b3b638 SD |
1611 | if (waitqueue_active(&area->wq)) |
1612 | wake_up(&area->wq); | |
1613 | ||
1614 | tsk->utask->xol_vaddr = 0; | |
1615 | } | |
1616 | } | |
1617 | ||
72e6ae28 VK |
1618 | void __weak arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr, |
1619 | void *src, unsigned long len) | |
1620 | { | |
1621 | /* Initialize the slot */ | |
1622 | copy_to_page(page, vaddr, src, len); | |
1623 | ||
1624 | /* | |
1625 | * We probably need flush_icache_user_range() but it needs vma. | |
1626 | * This should work on most of architectures by default. If | |
1627 | * architecture needs to do something different it can define | |
1628 | * its own version of the function. | |
1629 | */ | |
1630 | flush_dcache_page(page); | |
1631 | } | |
1632 | ||
0326f5a9 SD |
1633 | /** |
1634 | * uprobe_get_swbp_addr - compute address of swbp given post-swbp regs | |
1635 | * @regs: Reflects the saved state of the task after it has hit a breakpoint | |
1636 | * instruction. | |
1637 | * Return the address of the breakpoint instruction. | |
1638 | */ | |
1639 | unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs) | |
1640 | { | |
1641 | return instruction_pointer(regs) - UPROBE_SWBP_INSN_SIZE; | |
1642 | } | |
1643 | ||
b02ef20a ON |
1644 | unsigned long uprobe_get_trap_addr(struct pt_regs *regs) |
1645 | { | |
1646 | struct uprobe_task *utask = current->utask; | |
1647 | ||
1648 | if (unlikely(utask && utask->active_uprobe)) | |
1649 | return utask->vaddr; | |
1650 | ||
1651 | return instruction_pointer(regs); | |
1652 | } | |
1653 | ||
2bb5e840 ON |
1654 | static struct return_instance *free_ret_instance(struct return_instance *ri) |
1655 | { | |
1656 | struct return_instance *next = ri->next; | |
1657 | put_uprobe(ri->uprobe); | |
1658 | kfree(ri); | |
1659 | return next; | |
1660 | } | |
1661 | ||
0326f5a9 SD |
1662 | /* |
1663 | * Called with no locks held. | |
788faab7 | 1664 | * Called in context of an exiting or an exec-ing thread. |
0326f5a9 SD |
1665 | */ |
1666 | void uprobe_free_utask(struct task_struct *t) | |
1667 | { | |
1668 | struct uprobe_task *utask = t->utask; | |
2bb5e840 | 1669 | struct return_instance *ri; |
0326f5a9 | 1670 | |
0326f5a9 SD |
1671 | if (!utask) |
1672 | return; | |
1673 | ||
1674 | if (utask->active_uprobe) | |
1675 | put_uprobe(utask->active_uprobe); | |
1676 | ||
0dfd0eb8 | 1677 | ri = utask->return_instances; |
2bb5e840 ON |
1678 | while (ri) |
1679 | ri = free_ret_instance(ri); | |
0dfd0eb8 | 1680 | |
d4b3b638 | 1681 | xol_free_insn_slot(t); |
0326f5a9 SD |
1682 | kfree(utask); |
1683 | t->utask = NULL; | |
1684 | } | |
1685 | ||
0326f5a9 | 1686 | /* |
5a2df662 ON |
1687 | * Allocate a uprobe_task object for the task if if necessary. |
1688 | * Called when the thread hits a breakpoint. | |
0326f5a9 SD |
1689 | * |
1690 | * Returns: | |
1691 | * - pointer to new uprobe_task on success | |
1692 | * - NULL otherwise | |
1693 | */ | |
5a2df662 | 1694 | static struct uprobe_task *get_utask(void) |
0326f5a9 | 1695 | { |
5a2df662 ON |
1696 | if (!current->utask) |
1697 | current->utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL); | |
1698 | return current->utask; | |
0326f5a9 SD |
1699 | } |
1700 | ||
248d3a7b ON |
1701 | static int dup_utask(struct task_struct *t, struct uprobe_task *o_utask) |
1702 | { | |
1703 | struct uprobe_task *n_utask; | |
1704 | struct return_instance **p, *o, *n; | |
1705 | ||
1706 | n_utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL); | |
1707 | if (!n_utask) | |
1708 | return -ENOMEM; | |
1709 | t->utask = n_utask; | |
1710 | ||
1711 | p = &n_utask->return_instances; | |
1712 | for (o = o_utask->return_instances; o; o = o->next) { | |
1713 | n = kmalloc(sizeof(struct return_instance), GFP_KERNEL); | |
1714 | if (!n) | |
1715 | return -ENOMEM; | |
1716 | ||
1717 | *n = *o; | |
f231722a | 1718 | get_uprobe(n->uprobe); |
248d3a7b ON |
1719 | n->next = NULL; |
1720 | ||
1721 | *p = n; | |
1722 | p = &n->next; | |
1723 | n_utask->depth++; | |
1724 | } | |
1725 | ||
1726 | return 0; | |
1727 | } | |
1728 | ||
1729 | static void uprobe_warn(struct task_struct *t, const char *msg) | |
1730 | { | |
1731 | pr_warn("uprobe: %s:%d failed to %s\n", | |
1732 | current->comm, current->pid, msg); | |
1733 | } | |
1734 | ||
aa59c53f ON |
1735 | static void dup_xol_work(struct callback_head *work) |
1736 | { | |
aa59c53f ON |
1737 | if (current->flags & PF_EXITING) |
1738 | return; | |
1739 | ||
598fdc1d MH |
1740 | if (!__create_xol_area(current->utask->dup_xol_addr) && |
1741 | !fatal_signal_pending(current)) | |
aa59c53f ON |
1742 | uprobe_warn(current, "dup xol area"); |
1743 | } | |
1744 | ||
b68e0749 ON |
1745 | /* |
1746 | * Called in context of a new clone/fork from copy_process. | |
1747 | */ | |
3ab67966 | 1748 | void uprobe_copy_process(struct task_struct *t, unsigned long flags) |
b68e0749 | 1749 | { |
248d3a7b ON |
1750 | struct uprobe_task *utask = current->utask; |
1751 | struct mm_struct *mm = current->mm; | |
aa59c53f | 1752 | struct xol_area *area; |
248d3a7b | 1753 | |
b68e0749 | 1754 | t->utask = NULL; |
248d3a7b | 1755 | |
3ab67966 ON |
1756 | if (!utask || !utask->return_instances) |
1757 | return; | |
1758 | ||
1759 | if (mm == t->mm && !(flags & CLONE_VFORK)) | |
248d3a7b ON |
1760 | return; |
1761 | ||
1762 | if (dup_utask(t, utask)) | |
1763 | return uprobe_warn(t, "dup ret instances"); | |
aa59c53f ON |
1764 | |
1765 | /* The task can fork() after dup_xol_work() fails */ | |
1766 | area = mm->uprobes_state.xol_area; | |
1767 | if (!area) | |
1768 | return uprobe_warn(t, "dup xol area"); | |
1769 | ||
3ab67966 ON |
1770 | if (mm == t->mm) |
1771 | return; | |
1772 | ||
32473431 ON |
1773 | t->utask->dup_xol_addr = area->vaddr; |
1774 | init_task_work(&t->utask->dup_xol_work, dup_xol_work); | |
1775 | task_work_add(t, &t->utask->dup_xol_work, true); | |
b68e0749 ON |
1776 | } |
1777 | ||
e78aebfd AA |
1778 | /* |
1779 | * Current area->vaddr notion assume the trampoline address is always | |
1780 | * equal area->vaddr. | |
1781 | * | |
1782 | * Returns -1 in case the xol_area is not allocated. | |
1783 | */ | |
1784 | static unsigned long get_trampoline_vaddr(void) | |
1785 | { | |
1786 | struct xol_area *area; | |
1787 | unsigned long trampoline_vaddr = -1; | |
1788 | ||
5c6338b4 PM |
1789 | /* Pairs with xol_add_vma() smp_store_release() */ |
1790 | area = READ_ONCE(current->mm->uprobes_state.xol_area); /* ^^^ */ | |
e78aebfd AA |
1791 | if (area) |
1792 | trampoline_vaddr = area->vaddr; | |
1793 | ||
1794 | return trampoline_vaddr; | |
1795 | } | |
1796 | ||
db087ef6 ON |
1797 | static void cleanup_return_instances(struct uprobe_task *utask, bool chained, |
1798 | struct pt_regs *regs) | |
a5b7e1a8 ON |
1799 | { |
1800 | struct return_instance *ri = utask->return_instances; | |
db087ef6 | 1801 | enum rp_check ctx = chained ? RP_CHECK_CHAIN_CALL : RP_CHECK_CALL; |
86dcb702 ON |
1802 | |
1803 | while (ri && !arch_uretprobe_is_alive(ri, ctx, regs)) { | |
a5b7e1a8 ON |
1804 | ri = free_ret_instance(ri); |
1805 | utask->depth--; | |
1806 | } | |
1807 | utask->return_instances = ri; | |
1808 | } | |
1809 | ||
0dfd0eb8 AA |
1810 | static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs) |
1811 | { | |
1812 | struct return_instance *ri; | |
1813 | struct uprobe_task *utask; | |
1814 | unsigned long orig_ret_vaddr, trampoline_vaddr; | |
db087ef6 | 1815 | bool chained; |
0dfd0eb8 AA |
1816 | |
1817 | if (!get_xol_area()) | |
1818 | return; | |
1819 | ||
1820 | utask = get_utask(); | |
1821 | if (!utask) | |
1822 | return; | |
1823 | ||
ded49c55 AA |
1824 | if (utask->depth >= MAX_URETPROBE_DEPTH) { |
1825 | printk_ratelimited(KERN_INFO "uprobe: omit uretprobe due to" | |
1826 | " nestedness limit pid/tgid=%d/%d\n", | |
1827 | current->pid, current->tgid); | |
1828 | return; | |
1829 | } | |
1830 | ||
6c58d0e4 | 1831 | ri = kmalloc(sizeof(struct return_instance), GFP_KERNEL); |
0dfd0eb8 | 1832 | if (!ri) |
6c58d0e4 | 1833 | return; |
0dfd0eb8 AA |
1834 | |
1835 | trampoline_vaddr = get_trampoline_vaddr(); | |
1836 | orig_ret_vaddr = arch_uretprobe_hijack_return_addr(trampoline_vaddr, regs); | |
1837 | if (orig_ret_vaddr == -1) | |
1838 | goto fail; | |
1839 | ||
a5b7e1a8 | 1840 | /* drop the entries invalidated by longjmp() */ |
db087ef6 ON |
1841 | chained = (orig_ret_vaddr == trampoline_vaddr); |
1842 | cleanup_return_instances(utask, chained, regs); | |
a5b7e1a8 | 1843 | |
0dfd0eb8 AA |
1844 | /* |
1845 | * We don't want to keep trampoline address in stack, rather keep the | |
1846 | * original return address of first caller thru all the consequent | |
1847 | * instances. This also makes breakpoint unwrapping easier. | |
1848 | */ | |
db087ef6 | 1849 | if (chained) { |
0dfd0eb8 AA |
1850 | if (!utask->return_instances) { |
1851 | /* | |
1852 | * This situation is not possible. Likely we have an | |
1853 | * attack from user-space. | |
1854 | */ | |
6c58d0e4 | 1855 | uprobe_warn(current, "handle tail call"); |
0dfd0eb8 AA |
1856 | goto fail; |
1857 | } | |
0dfd0eb8 AA |
1858 | orig_ret_vaddr = utask->return_instances->orig_ret_vaddr; |
1859 | } | |
1860 | ||
f231722a | 1861 | ri->uprobe = get_uprobe(uprobe); |
0dfd0eb8 | 1862 | ri->func = instruction_pointer(regs); |
7b868e48 | 1863 | ri->stack = user_stack_pointer(regs); |
0dfd0eb8 AA |
1864 | ri->orig_ret_vaddr = orig_ret_vaddr; |
1865 | ri->chained = chained; | |
1866 | ||
ded49c55 | 1867 | utask->depth++; |
0dfd0eb8 AA |
1868 | ri->next = utask->return_instances; |
1869 | utask->return_instances = ri; | |
1870 | ||
1871 | return; | |
0dfd0eb8 AA |
1872 | fail: |
1873 | kfree(ri); | |
1874 | } | |
1875 | ||
0326f5a9 SD |
1876 | /* Prepare to single-step probed instruction out of line. */ |
1877 | static int | |
a6cb3f6d | 1878 | pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long bp_vaddr) |
0326f5a9 | 1879 | { |
a6cb3f6d ON |
1880 | struct uprobe_task *utask; |
1881 | unsigned long xol_vaddr; | |
aba51024 | 1882 | int err; |
a6cb3f6d | 1883 | |
608e7427 ON |
1884 | utask = get_utask(); |
1885 | if (!utask) | |
1886 | return -ENOMEM; | |
a6cb3f6d ON |
1887 | |
1888 | xol_vaddr = xol_get_insn_slot(uprobe); | |
1889 | if (!xol_vaddr) | |
1890 | return -ENOMEM; | |
1891 | ||
1892 | utask->xol_vaddr = xol_vaddr; | |
1893 | utask->vaddr = bp_vaddr; | |
d4b3b638 | 1894 | |
aba51024 ON |
1895 | err = arch_uprobe_pre_xol(&uprobe->arch, regs); |
1896 | if (unlikely(err)) { | |
1897 | xol_free_insn_slot(current); | |
1898 | return err; | |
1899 | } | |
1900 | ||
608e7427 ON |
1901 | utask->active_uprobe = uprobe; |
1902 | utask->state = UTASK_SSTEP; | |
aba51024 | 1903 | return 0; |
0326f5a9 SD |
1904 | } |
1905 | ||
1906 | /* | |
1907 | * If we are singlestepping, then ensure this thread is not connected to | |
1908 | * non-fatal signals until completion of singlestep. When xol insn itself | |
1909 | * triggers the signal, restart the original insn even if the task is | |
1910 | * already SIGKILL'ed (since coredump should report the correct ip). This | |
1911 | * is even more important if the task has a handler for SIGSEGV/etc, The | |
1912 | * _same_ instruction should be repeated again after return from the signal | |
1913 | * handler, and SSTEP can never finish in this case. | |
1914 | */ | |
1915 | bool uprobe_deny_signal(void) | |
1916 | { | |
1917 | struct task_struct *t = current; | |
1918 | struct uprobe_task *utask = t->utask; | |
1919 | ||
1920 | if (likely(!utask || !utask->active_uprobe)) | |
1921 | return false; | |
1922 | ||
1923 | WARN_ON_ONCE(utask->state != UTASK_SSTEP); | |
1924 | ||
1925 | if (signal_pending(t)) { | |
1926 | spin_lock_irq(&t->sighand->siglock); | |
1927 | clear_tsk_thread_flag(t, TIF_SIGPENDING); | |
1928 | spin_unlock_irq(&t->sighand->siglock); | |
1929 | ||
1930 | if (__fatal_signal_pending(t) || arch_uprobe_xol_was_trapped(t)) { | |
1931 | utask->state = UTASK_SSTEP_TRAPPED; | |
1932 | set_tsk_thread_flag(t, TIF_UPROBE); | |
0326f5a9 SD |
1933 | } |
1934 | } | |
1935 | ||
1936 | return true; | |
1937 | } | |
1938 | ||
499a4f3e ON |
1939 | static void mmf_recalc_uprobes(struct mm_struct *mm) |
1940 | { | |
1941 | struct vm_area_struct *vma; | |
1942 | ||
1943 | for (vma = mm->mmap; vma; vma = vma->vm_next) { | |
1944 | if (!valid_vma(vma, false)) | |
1945 | continue; | |
1946 | /* | |
1947 | * This is not strictly accurate, we can race with | |
1948 | * uprobe_unregister() and see the already removed | |
1949 | * uprobe if delete_uprobe() was not yet called. | |
63633cbf | 1950 | * Or this uprobe can be filtered out. |
499a4f3e ON |
1951 | */ |
1952 | if (vma_has_uprobes(vma, vma->vm_start, vma->vm_end)) | |
1953 | return; | |
1954 | } | |
1955 | ||
1956 | clear_bit(MMF_HAS_UPROBES, &mm->flags); | |
1957 | } | |
1958 | ||
0908ad6e | 1959 | static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr) |
ec75fba9 ON |
1960 | { |
1961 | struct page *page; | |
1962 | uprobe_opcode_t opcode; | |
1963 | int result; | |
1964 | ||
1965 | pagefault_disable(); | |
bd28b145 | 1966 | result = __get_user(opcode, (uprobe_opcode_t __user *)vaddr); |
ec75fba9 ON |
1967 | pagefault_enable(); |
1968 | ||
1969 | if (likely(result == 0)) | |
1970 | goto out; | |
1971 | ||
1e987790 DH |
1972 | /* |
1973 | * The NULL 'tsk' here ensures that any faults that occur here | |
1974 | * will not be accounted to the task. 'mm' *is* current->mm, | |
1975 | * but we treat this as a 'remote' access since it is | |
1976 | * essentially a kernel access to the memory. | |
1977 | */ | |
9beae1ea | 1978 | result = get_user_pages_remote(NULL, mm, vaddr, 1, FOLL_FORCE, &page, |
5b56d49f | 1979 | NULL, NULL); |
ec75fba9 ON |
1980 | if (result < 0) |
1981 | return result; | |
1982 | ||
ab0d805c | 1983 | copy_from_page(page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE); |
ec75fba9 ON |
1984 | put_page(page); |
1985 | out: | |
0908ad6e AM |
1986 | /* This needs to return true for any variant of the trap insn */ |
1987 | return is_trap_insn(&opcode); | |
ec75fba9 ON |
1988 | } |
1989 | ||
d790d346 | 1990 | static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp) |
0326f5a9 | 1991 | { |
3a9ea052 ON |
1992 | struct mm_struct *mm = current->mm; |
1993 | struct uprobe *uprobe = NULL; | |
0326f5a9 | 1994 | struct vm_area_struct *vma; |
0326f5a9 | 1995 | |
0326f5a9 SD |
1996 | down_read(&mm->mmap_sem); |
1997 | vma = find_vma(mm, bp_vaddr); | |
3a9ea052 ON |
1998 | if (vma && vma->vm_start <= bp_vaddr) { |
1999 | if (valid_vma(vma, false)) { | |
f281769e | 2000 | struct inode *inode = file_inode(vma->vm_file); |
cb113b47 | 2001 | loff_t offset = vaddr_to_offset(vma, bp_vaddr); |
0326f5a9 | 2002 | |
3a9ea052 ON |
2003 | uprobe = find_uprobe(inode, offset); |
2004 | } | |
d790d346 ON |
2005 | |
2006 | if (!uprobe) | |
0908ad6e | 2007 | *is_swbp = is_trap_at_addr(mm, bp_vaddr); |
d790d346 ON |
2008 | } else { |
2009 | *is_swbp = -EFAULT; | |
0326f5a9 | 2010 | } |
499a4f3e ON |
2011 | |
2012 | if (!uprobe && test_and_clear_bit(MMF_RECALC_UPROBES, &mm->flags)) | |
2013 | mmf_recalc_uprobes(mm); | |
0326f5a9 SD |
2014 | up_read(&mm->mmap_sem); |
2015 | ||
3a9ea052 ON |
2016 | return uprobe; |
2017 | } | |
2018 | ||
da1816b1 ON |
2019 | static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs) |
2020 | { | |
2021 | struct uprobe_consumer *uc; | |
2022 | int remove = UPROBE_HANDLER_REMOVE; | |
0dfd0eb8 | 2023 | bool need_prep = false; /* prepare return uprobe, when needed */ |
da1816b1 ON |
2024 | |
2025 | down_read(&uprobe->register_rwsem); | |
2026 | for (uc = uprobe->consumers; uc; uc = uc->next) { | |
ea024870 | 2027 | int rc = 0; |
da1816b1 | 2028 | |
ea024870 AA |
2029 | if (uc->handler) { |
2030 | rc = uc->handler(uc, regs); | |
2031 | WARN(rc & ~UPROBE_HANDLER_MASK, | |
d75f773c | 2032 | "bad rc=0x%x from %ps()\n", rc, uc->handler); |
ea024870 | 2033 | } |
0dfd0eb8 AA |
2034 | |
2035 | if (uc->ret_handler) | |
2036 | need_prep = true; | |
2037 | ||
da1816b1 ON |
2038 | remove &= rc; |
2039 | } | |
2040 | ||
0dfd0eb8 AA |
2041 | if (need_prep && !remove) |
2042 | prepare_uretprobe(uprobe, regs); /* put bp at return */ | |
2043 | ||
da1816b1 ON |
2044 | if (remove && uprobe->consumers) { |
2045 | WARN_ON(!uprobe_is_active(uprobe)); | |
2046 | unapply_uprobe(uprobe, current->mm); | |
2047 | } | |
2048 | up_read(&uprobe->register_rwsem); | |
2049 | } | |
2050 | ||
fec8898d AA |
2051 | static void |
2052 | handle_uretprobe_chain(struct return_instance *ri, struct pt_regs *regs) | |
2053 | { | |
2054 | struct uprobe *uprobe = ri->uprobe; | |
2055 | struct uprobe_consumer *uc; | |
2056 | ||
2057 | down_read(&uprobe->register_rwsem); | |
2058 | for (uc = uprobe->consumers; uc; uc = uc->next) { | |
2059 | if (uc->ret_handler) | |
2060 | uc->ret_handler(uc, ri->func, regs); | |
2061 | } | |
2062 | up_read(&uprobe->register_rwsem); | |
2063 | } | |
2064 | ||
a83cfeb9 ON |
2065 | static struct return_instance *find_next_ret_chain(struct return_instance *ri) |
2066 | { | |
2067 | bool chained; | |
2068 | ||
2069 | do { | |
2070 | chained = ri->chained; | |
2071 | ri = ri->next; /* can't be NULL if chained */ | |
2072 | } while (chained); | |
2073 | ||
2074 | return ri; | |
2075 | } | |
2076 | ||
0b5256c7 | 2077 | static void handle_trampoline(struct pt_regs *regs) |
fec8898d AA |
2078 | { |
2079 | struct uprobe_task *utask; | |
a83cfeb9 | 2080 | struct return_instance *ri, *next; |
5eeb50de | 2081 | bool valid; |
fec8898d AA |
2082 | |
2083 | utask = current->utask; | |
2084 | if (!utask) | |
0b5256c7 | 2085 | goto sigill; |
fec8898d AA |
2086 | |
2087 | ri = utask->return_instances; | |
2088 | if (!ri) | |
0b5256c7 | 2089 | goto sigill; |
fec8898d | 2090 | |
a83cfeb9 | 2091 | do { |
5eeb50de ON |
2092 | /* |
2093 | * We should throw out the frames invalidated by longjmp(). | |
2094 | * If this chain is valid, then the next one should be alive | |
2095 | * or NULL; the latter case means that nobody but ri->func | |
2096 | * could hit this trampoline on return. TODO: sigaltstack(). | |
2097 | */ | |
2098 | next = find_next_ret_chain(ri); | |
86dcb702 | 2099 | valid = !next || arch_uretprobe_is_alive(next, RP_CHECK_RET, regs); |
5eeb50de ON |
2100 | |
2101 | instruction_pointer_set(regs, ri->orig_ret_vaddr); | |
2102 | do { | |
2103 | if (valid) | |
2104 | handle_uretprobe_chain(ri, regs); | |
2105 | ri = free_ret_instance(ri); | |
2106 | utask->depth--; | |
2107 | } while (ri != next); | |
2108 | } while (!valid); | |
fec8898d AA |
2109 | |
2110 | utask->return_instances = ri; | |
0b5256c7 ON |
2111 | return; |
2112 | ||
2113 | sigill: | |
2114 | uprobe_warn(current, "handle uretprobe, sending SIGILL."); | |
55a3235f | 2115 | force_sig(SIGILL, current); |
fec8898d | 2116 | |
fec8898d AA |
2117 | } |
2118 | ||
6fe50a28 DL |
2119 | bool __weak arch_uprobe_ignore(struct arch_uprobe *aup, struct pt_regs *regs) |
2120 | { | |
2121 | return false; | |
2122 | } | |
2123 | ||
86dcb702 ON |
2124 | bool __weak arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx, |
2125 | struct pt_regs *regs) | |
97da8976 ON |
2126 | { |
2127 | return true; | |
2128 | } | |
2129 | ||
3a9ea052 ON |
2130 | /* |
2131 | * Run handler and ask thread to singlestep. | |
2132 | * Ensure all non-fatal signals cannot interrupt thread while it singlesteps. | |
2133 | */ | |
2134 | static void handle_swbp(struct pt_regs *regs) | |
2135 | { | |
3a9ea052 ON |
2136 | struct uprobe *uprobe; |
2137 | unsigned long bp_vaddr; | |
56bb4cf6 | 2138 | int uninitialized_var(is_swbp); |
3a9ea052 ON |
2139 | |
2140 | bp_vaddr = uprobe_get_swbp_addr(regs); | |
0b5256c7 ON |
2141 | if (bp_vaddr == get_trampoline_vaddr()) |
2142 | return handle_trampoline(regs); | |
fec8898d AA |
2143 | |
2144 | uprobe = find_active_uprobe(bp_vaddr, &is_swbp); | |
0326f5a9 | 2145 | if (!uprobe) { |
56bb4cf6 ON |
2146 | if (is_swbp > 0) { |
2147 | /* No matching uprobe; signal SIGTRAP. */ | |
2148 | send_sig(SIGTRAP, current, 0); | |
2149 | } else { | |
2150 | /* | |
2151 | * Either we raced with uprobe_unregister() or we can't | |
2152 | * access this memory. The latter is only possible if | |
2153 | * another thread plays with our ->mm. In both cases | |
2154 | * we can simply restart. If this vma was unmapped we | |
2155 | * can pretend this insn was not executed yet and get | |
2156 | * the (correct) SIGSEGV after restart. | |
2157 | */ | |
2158 | instruction_pointer_set(regs, bp_vaddr); | |
2159 | } | |
0326f5a9 SD |
2160 | return; |
2161 | } | |
74e59dfc ON |
2162 | |
2163 | /* change it in advance for ->handler() and restart */ | |
2164 | instruction_pointer_set(regs, bp_vaddr); | |
2165 | ||
142b18dd ON |
2166 | /* |
2167 | * TODO: move copy_insn/etc into _register and remove this hack. | |
2168 | * After we hit the bp, _unregister + _register can install the | |
2169 | * new and not-yet-analyzed uprobe at the same address, restart. | |
2170 | */ | |
71434f2f | 2171 | if (unlikely(!test_bit(UPROBE_COPY_INSN, &uprobe->flags))) |
74e59dfc | 2172 | goto out; |
0326f5a9 | 2173 | |
09d3f015 AP |
2174 | /* |
2175 | * Pairs with the smp_wmb() in prepare_uprobe(). | |
2176 | * | |
2177 | * Guarantees that if we see the UPROBE_COPY_INSN bit set, then | |
2178 | * we must also see the stores to &uprobe->arch performed by the | |
2179 | * prepare_uprobe() call. | |
2180 | */ | |
2181 | smp_rmb(); | |
2182 | ||
72fd293a ON |
2183 | /* Tracing handlers use ->utask to communicate with fetch methods */ |
2184 | if (!get_utask()) | |
2185 | goto out; | |
2186 | ||
6fe50a28 DL |
2187 | if (arch_uprobe_ignore(&uprobe->arch, regs)) |
2188 | goto out; | |
2189 | ||
0326f5a9 | 2190 | handler_chain(uprobe, regs); |
6fe50a28 | 2191 | |
8a6b1732 | 2192 | if (arch_uprobe_skip_sstep(&uprobe->arch, regs)) |
0578a970 | 2193 | goto out; |
0326f5a9 | 2194 | |
608e7427 | 2195 | if (!pre_ssout(uprobe, regs, bp_vaddr)) |
0326f5a9 | 2196 | return; |
0326f5a9 | 2197 | |
8a6b1732 | 2198 | /* arch_uprobe_skip_sstep() succeeded, or restart if can't singlestep */ |
0578a970 | 2199 | out: |
8bd87445 | 2200 | put_uprobe(uprobe); |
0326f5a9 SD |
2201 | } |
2202 | ||
2203 | /* | |
2204 | * Perform required fix-ups and disable singlestep. | |
2205 | * Allow pending signals to take effect. | |
2206 | */ | |
2207 | static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs) | |
2208 | { | |
2209 | struct uprobe *uprobe; | |
014940ba | 2210 | int err = 0; |
0326f5a9 SD |
2211 | |
2212 | uprobe = utask->active_uprobe; | |
2213 | if (utask->state == UTASK_SSTEP_ACK) | |
014940ba | 2214 | err = arch_uprobe_post_xol(&uprobe->arch, regs); |
0326f5a9 SD |
2215 | else if (utask->state == UTASK_SSTEP_TRAPPED) |
2216 | arch_uprobe_abort_xol(&uprobe->arch, regs); | |
2217 | else | |
2218 | WARN_ON_ONCE(1); | |
2219 | ||
2220 | put_uprobe(uprobe); | |
2221 | utask->active_uprobe = NULL; | |
2222 | utask->state = UTASK_RUNNING; | |
d4b3b638 | 2223 | xol_free_insn_slot(current); |
0326f5a9 SD |
2224 | |
2225 | spin_lock_irq(¤t->sighand->siglock); | |
2226 | recalc_sigpending(); /* see uprobe_deny_signal() */ | |
2227 | spin_unlock_irq(¤t->sighand->siglock); | |
014940ba ON |
2228 | |
2229 | if (unlikely(err)) { | |
2230 | uprobe_warn(current, "execute the probed insn, sending SIGILL."); | |
55a3235f | 2231 | force_sig(SIGILL, current); |
014940ba | 2232 | } |
0326f5a9 SD |
2233 | } |
2234 | ||
2235 | /* | |
1b08e907 ON |
2236 | * On breakpoint hit, breakpoint notifier sets the TIF_UPROBE flag and |
2237 | * allows the thread to return from interrupt. After that handle_swbp() | |
2238 | * sets utask->active_uprobe. | |
0326f5a9 | 2239 | * |
1b08e907 ON |
2240 | * On singlestep exception, singlestep notifier sets the TIF_UPROBE flag |
2241 | * and allows the thread to return from interrupt. | |
0326f5a9 SD |
2242 | * |
2243 | * While returning to userspace, thread notices the TIF_UPROBE flag and calls | |
2244 | * uprobe_notify_resume(). | |
2245 | */ | |
2246 | void uprobe_notify_resume(struct pt_regs *regs) | |
2247 | { | |
2248 | struct uprobe_task *utask; | |
2249 | ||
db023ea5 ON |
2250 | clear_thread_flag(TIF_UPROBE); |
2251 | ||
0326f5a9 | 2252 | utask = current->utask; |
1b08e907 | 2253 | if (utask && utask->active_uprobe) |
0326f5a9 | 2254 | handle_singlestep(utask, regs); |
1b08e907 ON |
2255 | else |
2256 | handle_swbp(regs); | |
0326f5a9 SD |
2257 | } |
2258 | ||
2259 | /* | |
2260 | * uprobe_pre_sstep_notifier gets called from interrupt context as part of | |
2261 | * notifier mechanism. Set TIF_UPROBE flag and indicate breakpoint hit. | |
2262 | */ | |
2263 | int uprobe_pre_sstep_notifier(struct pt_regs *regs) | |
2264 | { | |
0dfd0eb8 AA |
2265 | if (!current->mm) |
2266 | return 0; | |
2267 | ||
2268 | if (!test_bit(MMF_HAS_UPROBES, ¤t->mm->flags) && | |
2269 | (!current->utask || !current->utask->return_instances)) | |
0326f5a9 SD |
2270 | return 0; |
2271 | ||
0326f5a9 | 2272 | set_thread_flag(TIF_UPROBE); |
0326f5a9 SD |
2273 | return 1; |
2274 | } | |
2275 | ||
2276 | /* | |
2277 | * uprobe_post_sstep_notifier gets called in interrupt context as part of notifier | |
2278 | * mechanism. Set TIF_UPROBE flag and indicate completion of singlestep. | |
2279 | */ | |
2280 | int uprobe_post_sstep_notifier(struct pt_regs *regs) | |
2281 | { | |
2282 | struct uprobe_task *utask = current->utask; | |
2283 | ||
2284 | if (!current->mm || !utask || !utask->active_uprobe) | |
2285 | /* task is currently not uprobed */ | |
2286 | return 0; | |
2287 | ||
2288 | utask->state = UTASK_SSTEP_ACK; | |
2289 | set_thread_flag(TIF_UPROBE); | |
2290 | return 1; | |
2291 | } | |
2292 | ||
2293 | static struct notifier_block uprobe_exception_nb = { | |
2294 | .notifier_call = arch_uprobe_exception_notify, | |
2295 | .priority = INT_MAX-1, /* notified after kprobes, kgdb */ | |
2296 | }; | |
2297 | ||
aad42dd4 | 2298 | void __init uprobes_init(void) |
2b144498 SD |
2299 | { |
2300 | int i; | |
2301 | ||
66d06dff | 2302 | for (i = 0; i < UPROBES_HASH_SZ; i++) |
2b144498 | 2303 | mutex_init(&uprobes_mmap_mutex[i]); |
0326f5a9 | 2304 | |
aad42dd4 | 2305 | BUG_ON(percpu_init_rwsem(&dup_mmap_sem)); |
32cdba1e | 2306 | |
aad42dd4 | 2307 | BUG_ON(register_die_notifier(&uprobe_exception_nb)); |
2b144498 | 2308 | } |