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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 */ | |
5fcd079a | 22 | #include <linux/swap.h> /* folio_free_swap */ |
0326f5a9 SD |
23 | #include <linux/ptrace.h> /* user_enable_single_step */ |
24 | #include <linux/kdebug.h> /* notifier mechanism */ | |
32cdba1e | 25 | #include <linux/percpu-rwsem.h> |
aa59c53f | 26 | #include <linux/task_work.h> |
40814f68 | 27 | #include <linux/shmem_fs.h> |
f385cb85 | 28 | #include <linux/khugepaged.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 | |
2bf1acc2 | 49 | DEFINE_STATIC_PERCPU_RWSEM(dup_mmap_sem); |
32cdba1e | 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 |
fb4fb04f SL |
146 | * @old_page: the page we are replacing by new_page |
147 | * @new_page: the modified page we replace page by | |
2b144498 | 148 | * |
fb4fb04f SL |
149 | * If @new_page is NULL, only unmap @old_page. |
150 | * | |
151 | * Returns 0 on success, negative error code otherwise. | |
2b144498 | 152 | */ |
c517ee74 | 153 | static int __replace_page(struct vm_area_struct *vma, unsigned long addr, |
bdfaa2ee | 154 | struct page *old_page, struct page *new_page) |
2b144498 | 155 | { |
5fcd079a | 156 | struct folio *old_folio = page_folio(old_page); |
82e66bf7 | 157 | struct folio *new_folio; |
2b144498 | 158 | struct mm_struct *mm = vma->vm_mm; |
5fcd079a | 159 | DEFINE_FOLIO_VMA_WALK(pvmw, old_folio, vma, addr, 0); |
9f92448c | 160 | int err; |
ac46d4f3 | 161 | struct mmu_notifier_range range; |
00501b53 | 162 | |
7d4a8be0 | 163 | mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm, addr, |
6f4f13e8 | 164 | addr + PAGE_SIZE); |
ac46d4f3 | 165 | |
fb4fb04f | 166 | if (new_page) { |
82e66bf7 MWO |
167 | new_folio = page_folio(new_page); |
168 | err = mem_cgroup_charge(new_folio, vma->vm_mm, GFP_KERNEL); | |
fb4fb04f SL |
169 | if (err) |
170 | return err; | |
171 | } | |
2b144498 | 172 | |
5fcd079a MWO |
173 | /* For folio_free_swap() below */ |
174 | folio_lock(old_folio); | |
9f92448c | 175 | |
ac46d4f3 | 176 | mmu_notifier_invalidate_range_start(&range); |
9f92448c | 177 | err = -EAGAIN; |
9d82c694 | 178 | if (!page_vma_mapped_walk(&pvmw)) |
9f92448c | 179 | goto unlock; |
14fa2daa | 180 | VM_BUG_ON_PAGE(addr != pvmw.address, old_page); |
2b144498 | 181 | |
fb4fb04f | 182 | if (new_page) { |
82e66bf7 | 183 | folio_get(new_folio); |
40f2bbf7 | 184 | page_add_new_anon_rmap(new_page, vma, addr); |
82e66bf7 | 185 | folio_add_lru_vma(new_folio, vma); |
fb4fb04f SL |
186 | } else |
187 | /* no new page, just dec_mm_counter for old_page */ | |
188 | dec_mm_counter(mm, MM_ANONPAGES); | |
2b144498 | 189 | |
5fcd079a | 190 | if (!folio_test_anon(old_folio)) { |
bdfaa2ee | 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); | |
fb4fb04f SL |
197 | if (new_page) |
198 | set_pte_at_notify(mm, addr, pvmw.pte, | |
199 | mk_pte(new_page, vma->vm_page_prot)); | |
2b144498 | 200 | |
cea86fe2 | 201 | page_remove_rmap(old_page, vma, false); |
5fcd079a MWO |
202 | if (!folio_mapped(old_folio)) |
203 | folio_free_swap(old_folio); | |
14fa2daa | 204 | page_vma_mapped_walk_done(&pvmw); |
5fcd079a | 205 | folio_put(old_folio); |
194f8dcb | 206 | |
9f92448c ON |
207 | err = 0; |
208 | unlock: | |
ac46d4f3 | 209 | mmu_notifier_invalidate_range_end(&range); |
5fcd079a | 210 | folio_unlock(old_folio); |
9f92448c | 211 | return err; |
2b144498 SD |
212 | } |
213 | ||
214 | /** | |
5cb4ac3a | 215 | * is_swbp_insn - check if instruction is breakpoint instruction. |
2b144498 | 216 | * @insn: instruction to be checked. |
5cb4ac3a | 217 | * Default implementation of is_swbp_insn |
2b144498 SD |
218 | * Returns true if @insn is a breakpoint instruction. |
219 | */ | |
5cb4ac3a | 220 | bool __weak is_swbp_insn(uprobe_opcode_t *insn) |
2b144498 | 221 | { |
5cb4ac3a | 222 | return *insn == UPROBE_SWBP_INSN; |
2b144498 SD |
223 | } |
224 | ||
0908ad6e AM |
225 | /** |
226 | * is_trap_insn - check if instruction is breakpoint instruction. | |
227 | * @insn: instruction to be checked. | |
228 | * Default implementation of is_trap_insn | |
229 | * Returns true if @insn is a breakpoint instruction. | |
230 | * | |
231 | * This function is needed for the case where an architecture has multiple | |
232 | * trap instructions (like powerpc). | |
233 | */ | |
234 | bool __weak is_trap_insn(uprobe_opcode_t *insn) | |
235 | { | |
236 | return is_swbp_insn(insn); | |
237 | } | |
238 | ||
ab0d805c | 239 | static void copy_from_page(struct page *page, unsigned long vaddr, void *dst, int len) |
cceb55aa ON |
240 | { |
241 | void *kaddr = kmap_atomic(page); | |
ab0d805c | 242 | memcpy(dst, kaddr + (vaddr & ~PAGE_MASK), len); |
cceb55aa ON |
243 | kunmap_atomic(kaddr); |
244 | } | |
245 | ||
5669ccee ON |
246 | static void copy_to_page(struct page *page, unsigned long vaddr, const void *src, int len) |
247 | { | |
248 | void *kaddr = kmap_atomic(page); | |
249 | memcpy(kaddr + (vaddr & ~PAGE_MASK), src, len); | |
250 | kunmap_atomic(kaddr); | |
251 | } | |
252 | ||
ed6f6a50 ON |
253 | static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *new_opcode) |
254 | { | |
255 | uprobe_opcode_t old_opcode; | |
256 | bool is_swbp; | |
257 | ||
0908ad6e AM |
258 | /* |
259 | * Note: We only check if the old_opcode is UPROBE_SWBP_INSN here. | |
260 | * We do not check if it is any other 'trap variant' which could | |
261 | * be conditional trap instruction such as the one powerpc supports. | |
262 | * | |
263 | * The logic is that we do not care if the underlying instruction | |
264 | * is a trap variant; uprobes always wins over any other (gdb) | |
265 | * breakpoint. | |
266 | */ | |
ab0d805c | 267 | copy_from_page(page, vaddr, &old_opcode, UPROBE_SWBP_INSN_SIZE); |
ed6f6a50 ON |
268 | is_swbp = is_swbp_insn(&old_opcode); |
269 | ||
270 | if (is_swbp_insn(new_opcode)) { | |
271 | if (is_swbp) /* register: already installed? */ | |
272 | return 0; | |
273 | } else { | |
274 | if (!is_swbp) /* unregister: was it changed by us? */ | |
076a365b | 275 | return 0; |
ed6f6a50 ON |
276 | } |
277 | ||
278 | return 1; | |
279 | } | |
280 | ||
1cc33161 RB |
281 | static struct delayed_uprobe * |
282 | delayed_uprobe_check(struct uprobe *uprobe, struct mm_struct *mm) | |
283 | { | |
284 | struct delayed_uprobe *du; | |
285 | ||
286 | list_for_each_entry(du, &delayed_uprobe_list, list) | |
287 | if (du->uprobe == uprobe && du->mm == mm) | |
288 | return du; | |
289 | return NULL; | |
290 | } | |
291 | ||
292 | static int delayed_uprobe_add(struct uprobe *uprobe, struct mm_struct *mm) | |
293 | { | |
294 | struct delayed_uprobe *du; | |
295 | ||
296 | if (delayed_uprobe_check(uprobe, mm)) | |
297 | return 0; | |
298 | ||
299 | du = kzalloc(sizeof(*du), GFP_KERNEL); | |
300 | if (!du) | |
301 | return -ENOMEM; | |
302 | ||
303 | du->uprobe = uprobe; | |
304 | du->mm = mm; | |
305 | list_add(&du->list, &delayed_uprobe_list); | |
306 | return 0; | |
307 | } | |
308 | ||
309 | static void delayed_uprobe_delete(struct delayed_uprobe *du) | |
310 | { | |
311 | if (WARN_ON(!du)) | |
312 | return; | |
313 | list_del(&du->list); | |
314 | kfree(du); | |
315 | } | |
316 | ||
317 | static void delayed_uprobe_remove(struct uprobe *uprobe, struct mm_struct *mm) | |
318 | { | |
319 | struct list_head *pos, *q; | |
320 | struct delayed_uprobe *du; | |
321 | ||
322 | if (!uprobe && !mm) | |
323 | return; | |
324 | ||
325 | list_for_each_safe(pos, q, &delayed_uprobe_list) { | |
326 | du = list_entry(pos, struct delayed_uprobe, list); | |
327 | ||
328 | if (uprobe && du->uprobe != uprobe) | |
329 | continue; | |
330 | if (mm && du->mm != mm) | |
331 | continue; | |
332 | ||
333 | delayed_uprobe_delete(du); | |
334 | } | |
335 | } | |
336 | ||
337 | static bool valid_ref_ctr_vma(struct uprobe *uprobe, | |
338 | struct vm_area_struct *vma) | |
339 | { | |
340 | unsigned long vaddr = offset_to_vaddr(vma, uprobe->ref_ctr_offset); | |
341 | ||
342 | return uprobe->ref_ctr_offset && | |
343 | vma->vm_file && | |
344 | file_inode(vma->vm_file) == uprobe->inode && | |
345 | (vma->vm_flags & (VM_WRITE|VM_SHARED)) == VM_WRITE && | |
346 | vma->vm_start <= vaddr && | |
347 | vma->vm_end > vaddr; | |
348 | } | |
349 | ||
350 | static struct vm_area_struct * | |
351 | find_ref_ctr_vma(struct uprobe *uprobe, struct mm_struct *mm) | |
352 | { | |
fcb72a58 | 353 | VMA_ITERATOR(vmi, mm, 0); |
1cc33161 RB |
354 | struct vm_area_struct *tmp; |
355 | ||
fcb72a58 | 356 | for_each_vma(vmi, tmp) |
1cc33161 RB |
357 | if (valid_ref_ctr_vma(uprobe, tmp)) |
358 | return tmp; | |
359 | ||
360 | return NULL; | |
361 | } | |
362 | ||
363 | static int | |
364 | __update_ref_ctr(struct mm_struct *mm, unsigned long vaddr, short d) | |
365 | { | |
366 | void *kaddr; | |
367 | struct page *page; | |
368 | struct vm_area_struct *vma; | |
369 | int ret; | |
370 | short *ptr; | |
371 | ||
372 | if (!vaddr || !d) | |
373 | return -EINVAL; | |
374 | ||
64019a2e | 375 | ret = get_user_pages_remote(mm, vaddr, 1, |
1cc33161 RB |
376 | FOLL_WRITE, &page, &vma, NULL); |
377 | if (unlikely(ret <= 0)) { | |
378 | /* | |
379 | * We are asking for 1 page. If get_user_pages_remote() fails, | |
380 | * it may return 0, in that case we have to return error. | |
381 | */ | |
382 | return ret == 0 ? -EBUSY : ret; | |
383 | } | |
384 | ||
385 | kaddr = kmap_atomic(page); | |
386 | ptr = kaddr + (vaddr & ~PAGE_MASK); | |
387 | ||
388 | if (unlikely(*ptr + d < 0)) { | |
389 | pr_warn("ref_ctr going negative. vaddr: 0x%lx, " | |
390 | "curr val: %d, delta: %d\n", vaddr, *ptr, d); | |
391 | ret = -EINVAL; | |
392 | goto out; | |
393 | } | |
394 | ||
395 | *ptr += d; | |
396 | ret = 0; | |
397 | out: | |
398 | kunmap_atomic(kaddr); | |
399 | put_page(page); | |
400 | return ret; | |
401 | } | |
402 | ||
403 | static void update_ref_ctr_warn(struct uprobe *uprobe, | |
404 | struct mm_struct *mm, short d) | |
405 | { | |
406 | pr_warn("ref_ctr %s failed for inode: 0x%lx offset: " | |
407 | "0x%llx ref_ctr_offset: 0x%llx of mm: 0x%pK\n", | |
408 | d > 0 ? "increment" : "decrement", uprobe->inode->i_ino, | |
409 | (unsigned long long) uprobe->offset, | |
410 | (unsigned long long) uprobe->ref_ctr_offset, mm); | |
411 | } | |
412 | ||
413 | static int update_ref_ctr(struct uprobe *uprobe, struct mm_struct *mm, | |
414 | short d) | |
415 | { | |
416 | struct vm_area_struct *rc_vma; | |
417 | unsigned long rc_vaddr; | |
418 | int ret = 0; | |
419 | ||
420 | rc_vma = find_ref_ctr_vma(uprobe, mm); | |
421 | ||
422 | if (rc_vma) { | |
423 | rc_vaddr = offset_to_vaddr(rc_vma, uprobe->ref_ctr_offset); | |
424 | ret = __update_ref_ctr(mm, rc_vaddr, d); | |
425 | if (ret) | |
426 | update_ref_ctr_warn(uprobe, mm, d); | |
427 | ||
428 | if (d > 0) | |
429 | return ret; | |
430 | } | |
431 | ||
432 | mutex_lock(&delayed_uprobe_lock); | |
433 | if (d > 0) | |
434 | ret = delayed_uprobe_add(uprobe, mm); | |
435 | else | |
436 | delayed_uprobe_remove(uprobe, mm); | |
437 | mutex_unlock(&delayed_uprobe_lock); | |
438 | ||
439 | return ret; | |
440 | } | |
441 | ||
2b144498 SD |
442 | /* |
443 | * NOTE: | |
444 | * Expect the breakpoint instruction to be the smallest size instruction for | |
445 | * the architecture. If an arch has variable length instruction and the | |
446 | * breakpoint instruction is not of the smallest length instruction | |
0908ad6e | 447 | * supported by that architecture then we need to modify is_trap_at_addr and |
f72d41fa ON |
448 | * uprobe_write_opcode accordingly. This would never be a problem for archs |
449 | * that have fixed length instructions. | |
29dedee0 | 450 | * |
f72d41fa | 451 | * uprobe_write_opcode - write the opcode at a given virtual address. |
9ce4d216 | 452 | * @auprobe: arch specific probepoint information. |
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 | * | |
c1e8d7c6 | 457 | * Called with mm->mmap_lock 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 | 466 | int ret, is_register, ref_ctr_updated = 0; |
f385cb85 | 467 | bool orig_page_huge = false; |
aa5de305 | 468 | unsigned int gup_flags = FOLL_FORCE; |
1cc33161 RB |
469 | |
470 | is_register = is_swbp_insn(&opcode); | |
471 | uprobe = container_of(auprobe, struct uprobe, arch); | |
f403072c | 472 | |
5323ce71 | 473 | retry: |
aa5de305 SL |
474 | if (is_register) |
475 | gup_flags |= FOLL_SPLIT_PMD; | |
2b144498 | 476 | /* Read the page with vaddr into memory */ |
64019a2e | 477 | ret = get_user_pages_remote(mm, vaddr, 1, gup_flags, |
aa5de305 | 478 | &old_page, &vma, NULL); |
2b144498 SD |
479 | if (ret <= 0) |
480 | return ret; | |
7b2d81d4 | 481 | |
ed6f6a50 ON |
482 | ret = verify_opcode(old_page, vaddr, &opcode); |
483 | if (ret <= 0) | |
484 | goto put_old; | |
485 | ||
aa5de305 SL |
486 | if (WARN(!is_register && PageCompound(old_page), |
487 | "uprobe unregister should never work on compound page\n")) { | |
488 | ret = -EINVAL; | |
489 | goto put_old; | |
490 | } | |
491 | ||
1cc33161 RB |
492 | /* We are going to replace instruction, update ref_ctr. */ |
493 | if (!ref_ctr_updated && uprobe->ref_ctr_offset) { | |
494 | ret = update_ref_ctr(uprobe, mm, is_register ? 1 : -1); | |
495 | if (ret) | |
496 | goto put_old; | |
497 | ||
498 | ref_ctr_updated = 1; | |
499 | } | |
500 | ||
fb4fb04f SL |
501 | ret = 0; |
502 | if (!is_register && !PageAnon(old_page)) | |
503 | goto put_old; | |
504 | ||
29dedee0 ON |
505 | ret = anon_vma_prepare(vma); |
506 | if (ret) | |
507 | goto put_old; | |
508 | ||
2b144498 SD |
509 | ret = -ENOMEM; |
510 | new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr); | |
511 | if (!new_page) | |
9f92448c | 512 | goto put_old; |
2b144498 | 513 | |
29dedee0 | 514 | __SetPageUptodate(new_page); |
3f47107c ON |
515 | copy_highpage(new_page, old_page); |
516 | copy_to_page(new_page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE); | |
2b144498 | 517 | |
fb4fb04f SL |
518 | if (!is_register) { |
519 | struct page *orig_page; | |
520 | pgoff_t index; | |
521 | ||
522 | VM_BUG_ON_PAGE(!PageAnon(old_page), old_page); | |
523 | ||
524 | index = vaddr_to_offset(vma, vaddr & PAGE_MASK) >> PAGE_SHIFT; | |
525 | orig_page = find_get_page(vma->vm_file->f_inode->i_mapping, | |
526 | index); | |
527 | ||
528 | if (orig_page) { | |
529 | if (PageUptodate(orig_page) && | |
530 | pages_identical(new_page, orig_page)) { | |
531 | /* let go new_page */ | |
532 | put_page(new_page); | |
533 | new_page = NULL; | |
f385cb85 SL |
534 | |
535 | if (PageCompound(orig_page)) | |
536 | orig_page_huge = true; | |
fb4fb04f SL |
537 | } |
538 | put_page(orig_page); | |
539 | } | |
540 | } | |
541 | ||
c517ee74 | 542 | ret = __replace_page(vma, vaddr, old_page, new_page); |
fb4fb04f SL |
543 | if (new_page) |
544 | put_page(new_page); | |
9f92448c | 545 | put_old: |
7b2d81d4 IM |
546 | put_page(old_page); |
547 | ||
5323ce71 ON |
548 | if (unlikely(ret == -EAGAIN)) |
549 | goto retry; | |
1cc33161 RB |
550 | |
551 | /* Revert back reference counter if instruction update failed. */ | |
552 | if (ret && is_register && ref_ctr_updated) | |
553 | update_ref_ctr(uprobe, mm, -1); | |
554 | ||
f385cb85 SL |
555 | /* try collapse pmd for compound page */ |
556 | if (!ret && orig_page_huge) | |
34488399 | 557 | collapse_pte_mapped_thp(mm, vaddr, false); |
f385cb85 | 558 | |
2b144498 SD |
559 | return ret; |
560 | } | |
561 | ||
2b144498 | 562 | /** |
5cb4ac3a | 563 | * set_swbp - store breakpoint at a given address. |
e3343e6a | 564 | * @auprobe: arch specific probepoint information. |
2b144498 | 565 | * @mm: the probed process address space. |
2b144498 SD |
566 | * @vaddr: the virtual address to insert the opcode. |
567 | * | |
568 | * For mm @mm, store the breakpoint instruction at @vaddr. | |
569 | * Return 0 (success) or a negative errno. | |
570 | */ | |
5cb4ac3a | 571 | int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) |
2b144498 | 572 | { |
6d43743e | 573 | return uprobe_write_opcode(auprobe, mm, vaddr, UPROBE_SWBP_INSN); |
2b144498 SD |
574 | } |
575 | ||
576 | /** | |
577 | * set_orig_insn - Restore the original instruction. | |
578 | * @mm: the probed process address space. | |
e3343e6a | 579 | * @auprobe: arch specific probepoint information. |
2b144498 | 580 | * @vaddr: the virtual address to insert the opcode. |
2b144498 SD |
581 | * |
582 | * For mm @mm, restore the original opcode (opcode) at @vaddr. | |
583 | * Return 0 (success) or a negative errno. | |
584 | */ | |
7b2d81d4 | 585 | int __weak |
ded86e7c | 586 | set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) |
2b144498 | 587 | { |
6d43743e RB |
588 | return uprobe_write_opcode(auprobe, mm, vaddr, |
589 | *(uprobe_opcode_t *)&auprobe->insn); | |
2b144498 SD |
590 | } |
591 | ||
f231722a ON |
592 | static struct uprobe *get_uprobe(struct uprobe *uprobe) |
593 | { | |
ce59b8e9 | 594 | refcount_inc(&uprobe->ref); |
f231722a ON |
595 | return uprobe; |
596 | } | |
597 | ||
598 | static void put_uprobe(struct uprobe *uprobe) | |
599 | { | |
ce59b8e9 | 600 | if (refcount_dec_and_test(&uprobe->ref)) { |
1cc33161 RB |
601 | /* |
602 | * If application munmap(exec_vma) before uprobe_unregister() | |
603 | * gets called, we don't get a chance to remove uprobe from | |
604 | * delayed_uprobe_list from remove_breakpoint(). Do it here. | |
605 | */ | |
1aed58e6 | 606 | mutex_lock(&delayed_uprobe_lock); |
1cc33161 | 607 | delayed_uprobe_remove(uprobe, NULL); |
1aed58e6 | 608 | mutex_unlock(&delayed_uprobe_lock); |
f231722a | 609 | kfree(uprobe); |
1cc33161 | 610 | } |
f231722a ON |
611 | } |
612 | ||
a905e84e PZ |
613 | static __always_inline |
614 | int uprobe_cmp(const struct inode *l_inode, const loff_t l_offset, | |
615 | const struct uprobe *r) | |
2b144498 | 616 | { |
a905e84e | 617 | if (l_inode < r->inode) |
2b144498 | 618 | return -1; |
7b2d81d4 | 619 | |
a905e84e | 620 | if (l_inode > r->inode) |
2b144498 | 621 | return 1; |
2b144498 | 622 | |
a905e84e | 623 | if (l_offset < r->offset) |
7b2d81d4 IM |
624 | return -1; |
625 | ||
a905e84e | 626 | if (l_offset > r->offset) |
7b2d81d4 | 627 | return 1; |
2b144498 SD |
628 | |
629 | return 0; | |
630 | } | |
631 | ||
a905e84e PZ |
632 | #define __node_2_uprobe(node) \ |
633 | rb_entry((node), struct uprobe, rb_node) | |
634 | ||
635 | struct __uprobe_key { | |
636 | struct inode *inode; | |
637 | loff_t offset; | |
638 | }; | |
639 | ||
640 | static inline int __uprobe_cmp_key(const void *key, const struct rb_node *b) | |
641 | { | |
642 | const struct __uprobe_key *a = key; | |
643 | return uprobe_cmp(a->inode, a->offset, __node_2_uprobe(b)); | |
644 | } | |
645 | ||
646 | static inline int __uprobe_cmp(struct rb_node *a, const struct rb_node *b) | |
647 | { | |
648 | struct uprobe *u = __node_2_uprobe(a); | |
649 | return uprobe_cmp(u->inode, u->offset, __node_2_uprobe(b)); | |
650 | } | |
651 | ||
2b144498 SD |
652 | static struct uprobe *__find_uprobe(struct inode *inode, loff_t offset) |
653 | { | |
a905e84e PZ |
654 | struct __uprobe_key key = { |
655 | .inode = inode, | |
656 | .offset = offset, | |
657 | }; | |
658 | struct rb_node *node = rb_find(&key, &uprobes_tree, __uprobe_cmp_key); | |
659 | ||
660 | if (node) | |
b0d6d478 | 661 | return get_uprobe(__node_2_uprobe(node)); |
a905e84e | 662 | |
2b144498 SD |
663 | return NULL; |
664 | } | |
665 | ||
666 | /* | |
667 | * Find a uprobe corresponding to a given inode:offset | |
668 | * Acquires uprobes_treelock | |
669 | */ | |
670 | static struct uprobe *find_uprobe(struct inode *inode, loff_t offset) | |
671 | { | |
672 | struct uprobe *uprobe; | |
2b144498 | 673 | |
6f47caa0 | 674 | spin_lock(&uprobes_treelock); |
2b144498 | 675 | uprobe = __find_uprobe(inode, offset); |
6f47caa0 | 676 | spin_unlock(&uprobes_treelock); |
7b2d81d4 | 677 | |
2b144498 SD |
678 | return uprobe; |
679 | } | |
680 | ||
681 | static struct uprobe *__insert_uprobe(struct uprobe *uprobe) | |
682 | { | |
a905e84e | 683 | struct rb_node *node; |
2b144498 | 684 | |
a905e84e PZ |
685 | node = rb_find_add(&uprobe->rb_node, &uprobes_tree, __uprobe_cmp); |
686 | if (node) | |
687 | return get_uprobe(__node_2_uprobe(node)); | |
2b144498 | 688 | |
2b144498 | 689 | /* get access + creation ref */ |
ce59b8e9 | 690 | refcount_set(&uprobe->ref, 2); |
a905e84e | 691 | return NULL; |
2b144498 SD |
692 | } |
693 | ||
694 | /* | |
7b2d81d4 | 695 | * Acquire uprobes_treelock. |
2b144498 SD |
696 | * Matching uprobe already exists in rbtree; |
697 | * increment (access refcount) and return the matching uprobe. | |
698 | * | |
699 | * No matching uprobe; insert the uprobe in rb_tree; | |
700 | * get a double refcount (access + creation) and return NULL. | |
701 | */ | |
702 | static struct uprobe *insert_uprobe(struct uprobe *uprobe) | |
703 | { | |
2b144498 SD |
704 | struct uprobe *u; |
705 | ||
6f47caa0 | 706 | spin_lock(&uprobes_treelock); |
2b144498 | 707 | u = __insert_uprobe(uprobe); |
6f47caa0 | 708 | spin_unlock(&uprobes_treelock); |
7b2d81d4 | 709 | |
2b144498 SD |
710 | return u; |
711 | } | |
712 | ||
22bad382 RB |
713 | static void |
714 | ref_ctr_mismatch_warn(struct uprobe *cur_uprobe, struct uprobe *uprobe) | |
715 | { | |
716 | pr_warn("ref_ctr_offset mismatch. inode: 0x%lx offset: 0x%llx " | |
717 | "ref_ctr_offset(old): 0x%llx ref_ctr_offset(new): 0x%llx\n", | |
718 | uprobe->inode->i_ino, (unsigned long long) uprobe->offset, | |
719 | (unsigned long long) cur_uprobe->ref_ctr_offset, | |
720 | (unsigned long long) uprobe->ref_ctr_offset); | |
721 | } | |
722 | ||
1cc33161 RB |
723 | static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset, |
724 | loff_t ref_ctr_offset) | |
2b144498 SD |
725 | { |
726 | struct uprobe *uprobe, *cur_uprobe; | |
727 | ||
728 | uprobe = kzalloc(sizeof(struct uprobe), GFP_KERNEL); | |
729 | if (!uprobe) | |
730 | return NULL; | |
731 | ||
61f94203 | 732 | uprobe->inode = inode; |
2b144498 | 733 | uprobe->offset = offset; |
1cc33161 | 734 | uprobe->ref_ctr_offset = ref_ctr_offset; |
e591c8d7 | 735 | init_rwsem(&uprobe->register_rwsem); |
2b144498 | 736 | init_rwsem(&uprobe->consumer_rwsem); |
2b144498 SD |
737 | |
738 | /* add to uprobes_tree, sorted on inode:offset */ | |
739 | cur_uprobe = insert_uprobe(uprobe); | |
2b144498 SD |
740 | /* a uprobe exists for this inode:offset combination */ |
741 | if (cur_uprobe) { | |
22bad382 RB |
742 | if (cur_uprobe->ref_ctr_offset != uprobe->ref_ctr_offset) { |
743 | ref_ctr_mismatch_warn(cur_uprobe, uprobe); | |
744 | put_uprobe(cur_uprobe); | |
745 | kfree(uprobe); | |
746 | return ERR_PTR(-EINVAL); | |
747 | } | |
2b144498 SD |
748 | kfree(uprobe); |
749 | uprobe = cur_uprobe; | |
7b2d81d4 IM |
750 | } |
751 | ||
2b144498 SD |
752 | return uprobe; |
753 | } | |
754 | ||
9a98e03c | 755 | static void consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc) |
2b144498 SD |
756 | { |
757 | down_write(&uprobe->consumer_rwsem); | |
e3343e6a SD |
758 | uc->next = uprobe->consumers; |
759 | uprobe->consumers = uc; | |
2b144498 | 760 | up_write(&uprobe->consumer_rwsem); |
2b144498 SD |
761 | } |
762 | ||
763 | /* | |
e3343e6a SD |
764 | * For uprobe @uprobe, delete the consumer @uc. |
765 | * Return true if the @uc is deleted successfully | |
2b144498 SD |
766 | * or return false. |
767 | */ | |
e3343e6a | 768 | static bool consumer_del(struct uprobe *uprobe, struct uprobe_consumer *uc) |
2b144498 SD |
769 | { |
770 | struct uprobe_consumer **con; | |
771 | bool ret = false; | |
772 | ||
773 | down_write(&uprobe->consumer_rwsem); | |
774 | for (con = &uprobe->consumers; *con; con = &(*con)->next) { | |
e3343e6a SD |
775 | if (*con == uc) { |
776 | *con = uc->next; | |
2b144498 SD |
777 | ret = true; |
778 | break; | |
779 | } | |
780 | } | |
781 | up_write(&uprobe->consumer_rwsem); | |
7b2d81d4 | 782 | |
2b144498 SD |
783 | return ret; |
784 | } | |
785 | ||
2ded0980 ON |
786 | static int __copy_insn(struct address_space *mapping, struct file *filp, |
787 | void *insn, int nbytes, loff_t offset) | |
2b144498 | 788 | { |
2b144498 | 789 | struct page *page; |
2b144498 | 790 | /* |
40814f68 | 791 | * Ensure that the page that has the original instruction is populated |
7e0a1265 | 792 | * and in page-cache. If ->read_folio == NULL it must be shmem_mapping(), |
40814f68 | 793 | * see uprobe_register(). |
2b144498 | 794 | */ |
7e0a1265 | 795 | if (mapping->a_ops->read_folio) |
09cbfeaf | 796 | page = read_mapping_page(mapping, offset >> PAGE_SHIFT, filp); |
40814f68 | 797 | else |
09cbfeaf | 798 | page = shmem_read_mapping_page(mapping, offset >> PAGE_SHIFT); |
2b144498 SD |
799 | if (IS_ERR(page)) |
800 | return PTR_ERR(page); | |
801 | ||
2edb7b55 | 802 | copy_from_page(page, offset, insn, nbytes); |
09cbfeaf | 803 | put_page(page); |
7b2d81d4 | 804 | |
2b144498 SD |
805 | return 0; |
806 | } | |
807 | ||
d436615e | 808 | static int copy_insn(struct uprobe *uprobe, struct file *filp) |
2b144498 | 809 | { |
2ded0980 ON |
810 | struct address_space *mapping = uprobe->inode->i_mapping; |
811 | loff_t offs = uprobe->offset; | |
803200e2 ON |
812 | void *insn = &uprobe->arch.insn; |
813 | int size = sizeof(uprobe->arch.insn); | |
2ded0980 ON |
814 | int len, err = -EIO; |
815 | ||
816 | /* Copy only available bytes, -EIO if nothing was read */ | |
817 | do { | |
818 | if (offs >= i_size_read(uprobe->inode)) | |
819 | break; | |
820 | ||
821 | len = min_t(int, size, PAGE_SIZE - (offs & ~PAGE_MASK)); | |
822 | err = __copy_insn(mapping, filp, insn, len, offs); | |
fc36f595 | 823 | if (err) |
2ded0980 ON |
824 | break; |
825 | ||
826 | insn += len; | |
827 | offs += len; | |
828 | size -= len; | |
829 | } while (size); | |
830 | ||
831 | return err; | |
2b144498 SD |
832 | } |
833 | ||
cb9a19fe ON |
834 | static int prepare_uprobe(struct uprobe *uprobe, struct file *file, |
835 | struct mm_struct *mm, unsigned long vaddr) | |
836 | { | |
837 | int ret = 0; | |
838 | ||
71434f2f | 839 | if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) |
cb9a19fe ON |
840 | return ret; |
841 | ||
d4d3ccc6 ON |
842 | /* TODO: move this into _register, until then we abuse this sem. */ |
843 | down_write(&uprobe->consumer_rwsem); | |
71434f2f | 844 | if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) |
4710f05f ON |
845 | goto out; |
846 | ||
cb9a19fe ON |
847 | ret = copy_insn(uprobe, file); |
848 | if (ret) | |
849 | goto out; | |
850 | ||
851 | ret = -ENOTSUPP; | |
803200e2 | 852 | if (is_trap_insn((uprobe_opcode_t *)&uprobe->arch.insn)) |
cb9a19fe ON |
853 | goto out; |
854 | ||
855 | ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, vaddr); | |
856 | if (ret) | |
857 | goto out; | |
858 | ||
09d3f015 | 859 | smp_wmb(); /* pairs with the smp_rmb() in handle_swbp() */ |
71434f2f | 860 | set_bit(UPROBE_COPY_INSN, &uprobe->flags); |
cb9a19fe ON |
861 | |
862 | out: | |
d4d3ccc6 | 863 | up_write(&uprobe->consumer_rwsem); |
4710f05f | 864 | |
cb9a19fe ON |
865 | return ret; |
866 | } | |
867 | ||
8a7f2fa0 ON |
868 | static inline bool consumer_filter(struct uprobe_consumer *uc, |
869 | enum uprobe_filter_ctx ctx, struct mm_struct *mm) | |
806a98bd | 870 | { |
8a7f2fa0 | 871 | return !uc->filter || uc->filter(uc, ctx, mm); |
806a98bd ON |
872 | } |
873 | ||
8a7f2fa0 ON |
874 | static bool filter_chain(struct uprobe *uprobe, |
875 | enum uprobe_filter_ctx ctx, struct mm_struct *mm) | |
63633cbf | 876 | { |
1ff6fee5 ON |
877 | struct uprobe_consumer *uc; |
878 | bool ret = false; | |
879 | ||
880 | down_read(&uprobe->consumer_rwsem); | |
881 | for (uc = uprobe->consumers; uc; uc = uc->next) { | |
8a7f2fa0 | 882 | ret = consumer_filter(uc, ctx, mm); |
1ff6fee5 ON |
883 | if (ret) |
884 | break; | |
885 | } | |
886 | up_read(&uprobe->consumer_rwsem); | |
887 | ||
888 | return ret; | |
63633cbf ON |
889 | } |
890 | ||
e3343e6a SD |
891 | static int |
892 | install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, | |
816c03fb | 893 | struct vm_area_struct *vma, unsigned long vaddr) |
2b144498 | 894 | { |
f8ac4ec9 | 895 | bool first_uprobe; |
2b144498 SD |
896 | int ret; |
897 | ||
cb9a19fe ON |
898 | ret = prepare_uprobe(uprobe, vma->vm_file, mm, vaddr); |
899 | if (ret) | |
900 | return ret; | |
682968e0 | 901 | |
f8ac4ec9 ON |
902 | /* |
903 | * set MMF_HAS_UPROBES in advance for uprobe_pre_sstep_notifier(), | |
904 | * the task can hit this breakpoint right after __replace_page(). | |
905 | */ | |
906 | first_uprobe = !test_bit(MMF_HAS_UPROBES, &mm->flags); | |
907 | if (first_uprobe) | |
908 | set_bit(MMF_HAS_UPROBES, &mm->flags); | |
909 | ||
816c03fb | 910 | ret = set_swbp(&uprobe->arch, mm, vaddr); |
9f68f672 ON |
911 | if (!ret) |
912 | clear_bit(MMF_RECALC_UPROBES, &mm->flags); | |
913 | else if (first_uprobe) | |
f8ac4ec9 | 914 | clear_bit(MMF_HAS_UPROBES, &mm->flags); |
2b144498 SD |
915 | |
916 | return ret; | |
917 | } | |
918 | ||
076a365b | 919 | static int |
816c03fb | 920 | remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr) |
2b144498 | 921 | { |
9f68f672 | 922 | set_bit(MMF_RECALC_UPROBES, &mm->flags); |
076a365b | 923 | return set_orig_insn(&uprobe->arch, mm, vaddr); |
2b144498 SD |
924 | } |
925 | ||
06b7bcd8 ON |
926 | static inline bool uprobe_is_active(struct uprobe *uprobe) |
927 | { | |
928 | return !RB_EMPTY_NODE(&uprobe->rb_node); | |
929 | } | |
0326f5a9 | 930 | /* |
778b032d ON |
931 | * There could be threads that have already hit the breakpoint. They |
932 | * will recheck the current insn and restart if find_uprobe() fails. | |
933 | * See find_active_uprobe(). | |
0326f5a9 | 934 | */ |
2b144498 SD |
935 | static void delete_uprobe(struct uprobe *uprobe) |
936 | { | |
06b7bcd8 ON |
937 | if (WARN_ON(!uprobe_is_active(uprobe))) |
938 | return; | |
939 | ||
6f47caa0 | 940 | spin_lock(&uprobes_treelock); |
2b144498 | 941 | rb_erase(&uprobe->rb_node, &uprobes_tree); |
6f47caa0 | 942 | spin_unlock(&uprobes_treelock); |
06b7bcd8 | 943 | RB_CLEAR_NODE(&uprobe->rb_node); /* for uprobe_is_active() */ |
2b144498 | 944 | put_uprobe(uprobe); |
2b144498 SD |
945 | } |
946 | ||
26872090 ON |
947 | struct map_info { |
948 | struct map_info *next; | |
949 | struct mm_struct *mm; | |
816c03fb | 950 | unsigned long vaddr; |
26872090 ON |
951 | }; |
952 | ||
953 | static inline struct map_info *free_map_info(struct map_info *info) | |
2b144498 | 954 | { |
26872090 ON |
955 | struct map_info *next = info->next; |
956 | kfree(info); | |
957 | return next; | |
958 | } | |
959 | ||
960 | static struct map_info * | |
961 | build_map_info(struct address_space *mapping, loff_t offset, bool is_register) | |
962 | { | |
963 | unsigned long pgoff = offset >> PAGE_SHIFT; | |
2b144498 | 964 | struct vm_area_struct *vma; |
26872090 ON |
965 | struct map_info *curr = NULL; |
966 | struct map_info *prev = NULL; | |
967 | struct map_info *info; | |
968 | int more = 0; | |
2b144498 | 969 | |
26872090 | 970 | again: |
4a23717a | 971 | i_mmap_lock_read(mapping); |
6b2dbba8 | 972 | vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { |
2b144498 SD |
973 | if (!valid_vma(vma, is_register)) |
974 | continue; | |
975 | ||
7a5bfb66 ON |
976 | if (!prev && !more) { |
977 | /* | |
c8c06efa | 978 | * Needs GFP_NOWAIT to avoid i_mmap_rwsem recursion through |
7a5bfb66 ON |
979 | * reclaim. This is optimistic, no harm done if it fails. |
980 | */ | |
981 | prev = kmalloc(sizeof(struct map_info), | |
982 | GFP_NOWAIT | __GFP_NOMEMALLOC | __GFP_NOWARN); | |
983 | if (prev) | |
984 | prev->next = NULL; | |
985 | } | |
26872090 ON |
986 | if (!prev) { |
987 | more++; | |
988 | continue; | |
2b144498 | 989 | } |
2b144498 | 990 | |
388f7934 | 991 | if (!mmget_not_zero(vma->vm_mm)) |
26872090 | 992 | continue; |
7b2d81d4 | 993 | |
26872090 ON |
994 | info = prev; |
995 | prev = prev->next; | |
996 | info->next = curr; | |
997 | curr = info; | |
2b144498 | 998 | |
26872090 | 999 | info->mm = vma->vm_mm; |
57683f72 | 1000 | info->vaddr = offset_to_vaddr(vma, offset); |
26872090 | 1001 | } |
4a23717a | 1002 | i_mmap_unlock_read(mapping); |
2b144498 | 1003 | |
26872090 ON |
1004 | if (!more) |
1005 | goto out; | |
1006 | ||
1007 | prev = curr; | |
1008 | while (curr) { | |
1009 | mmput(curr->mm); | |
1010 | curr = curr->next; | |
1011 | } | |
7b2d81d4 | 1012 | |
26872090 ON |
1013 | do { |
1014 | info = kmalloc(sizeof(struct map_info), GFP_KERNEL); | |
1015 | if (!info) { | |
1016 | curr = ERR_PTR(-ENOMEM); | |
1017 | goto out; | |
1018 | } | |
1019 | info->next = prev; | |
1020 | prev = info; | |
1021 | } while (--more); | |
1022 | ||
1023 | goto again; | |
1024 | out: | |
1025 | while (prev) | |
1026 | prev = free_map_info(prev); | |
1027 | return curr; | |
2b144498 SD |
1028 | } |
1029 | ||
bdf8647c ON |
1030 | static int |
1031 | register_for_each_vma(struct uprobe *uprobe, struct uprobe_consumer *new) | |
2b144498 | 1032 | { |
bdf8647c | 1033 | bool is_register = !!new; |
26872090 ON |
1034 | struct map_info *info; |
1035 | int err = 0; | |
2b144498 | 1036 | |
32cdba1e | 1037 | percpu_down_write(&dup_mmap_sem); |
26872090 ON |
1038 | info = build_map_info(uprobe->inode->i_mapping, |
1039 | uprobe->offset, is_register); | |
32cdba1e ON |
1040 | if (IS_ERR(info)) { |
1041 | err = PTR_ERR(info); | |
1042 | goto out; | |
1043 | } | |
7b2d81d4 | 1044 | |
26872090 ON |
1045 | while (info) { |
1046 | struct mm_struct *mm = info->mm; | |
1047 | struct vm_area_struct *vma; | |
7b2d81d4 | 1048 | |
076a365b | 1049 | if (err && is_register) |
26872090 | 1050 | goto free; |
7b2d81d4 | 1051 | |
d8ed45c5 | 1052 | mmap_write_lock(mm); |
f4d6dfe5 ON |
1053 | vma = find_vma(mm, info->vaddr); |
1054 | if (!vma || !valid_vma(vma, is_register) || | |
f281769e | 1055 | file_inode(vma->vm_file) != uprobe->inode) |
26872090 ON |
1056 | goto unlock; |
1057 | ||
f4d6dfe5 ON |
1058 | if (vma->vm_start > info->vaddr || |
1059 | vaddr_to_offset(vma, info->vaddr) != uprobe->offset) | |
26872090 | 1060 | goto unlock; |
2b144498 | 1061 | |
806a98bd ON |
1062 | if (is_register) { |
1063 | /* consult only the "caller", new consumer. */ | |
bdf8647c | 1064 | if (consumer_filter(new, |
8a7f2fa0 | 1065 | UPROBE_FILTER_REGISTER, mm)) |
806a98bd ON |
1066 | err = install_breakpoint(uprobe, mm, vma, info->vaddr); |
1067 | } else if (test_bit(MMF_HAS_UPROBES, &mm->flags)) { | |
8a7f2fa0 ON |
1068 | if (!filter_chain(uprobe, |
1069 | UPROBE_FILTER_UNREGISTER, mm)) | |
806a98bd ON |
1070 | err |= remove_breakpoint(uprobe, mm, info->vaddr); |
1071 | } | |
78f74116 | 1072 | |
26872090 | 1073 | unlock: |
d8ed45c5 | 1074 | mmap_write_unlock(mm); |
26872090 ON |
1075 | free: |
1076 | mmput(mm); | |
1077 | info = free_map_info(info); | |
2b144498 | 1078 | } |
32cdba1e ON |
1079 | out: |
1080 | percpu_up_write(&dup_mmap_sem); | |
26872090 | 1081 | return err; |
2b144498 SD |
1082 | } |
1083 | ||
38e967ae RB |
1084 | static void |
1085 | __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc) | |
2b144498 | 1086 | { |
04aab9b2 ON |
1087 | int err; |
1088 | ||
06d07139 | 1089 | if (WARN_ON(!consumer_del(uprobe, uc))) |
04aab9b2 | 1090 | return; |
2b144498 | 1091 | |
bdf8647c | 1092 | err = register_for_each_vma(uprobe, NULL); |
bb929284 ON |
1093 | /* TODO : cant unregister? schedule a worker thread */ |
1094 | if (!uprobe->consumers && !err) | |
1095 | delete_uprobe(uprobe); | |
2b144498 SD |
1096 | } |
1097 | ||
1098 | /* | |
7140ad38 | 1099 | * uprobe_unregister - unregister an already registered probe. |
38e967ae RB |
1100 | * @inode: the file in which the probe has to be removed. |
1101 | * @offset: offset from the start of the file. | |
1102 | * @uc: identify which probe if multiple probes are colocated. | |
1103 | */ | |
1104 | void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) | |
1105 | { | |
1106 | struct uprobe *uprobe; | |
1107 | ||
1108 | uprobe = find_uprobe(inode, offset); | |
1109 | if (WARN_ON(!uprobe)) | |
1110 | return; | |
1111 | ||
1112 | down_write(&uprobe->register_rwsem); | |
1113 | __uprobe_unregister(uprobe, uc); | |
1114 | up_write(&uprobe->register_rwsem); | |
1115 | put_uprobe(uprobe); | |
1116 | } | |
1117 | EXPORT_SYMBOL_GPL(uprobe_unregister); | |
1118 | ||
1119 | /* | |
1120 | * __uprobe_register - register a probe | |
2b144498 SD |
1121 | * @inode: the file in which the probe has to be placed. |
1122 | * @offset: offset from the start of the file. | |
e3343e6a | 1123 | * @uc: information on howto handle the probe.. |
2b144498 | 1124 | * |
38e967ae | 1125 | * Apart from the access refcount, __uprobe_register() takes a creation |
2b144498 SD |
1126 | * refcount (thro alloc_uprobe) if and only if this @uprobe is getting |
1127 | * inserted into the rbtree (i.e first consumer for a @inode:@offset | |
7b2d81d4 | 1128 | * tuple). Creation refcount stops uprobe_unregister from freeing the |
2b144498 | 1129 | * @uprobe even before the register operation is complete. Creation |
e3343e6a | 1130 | * refcount is released when the last @uc for the @uprobe |
38e967ae | 1131 | * unregisters. Caller of __uprobe_register() is required to keep @inode |
61f94203 | 1132 | * (and the containing mount) referenced. |
2b144498 SD |
1133 | * |
1134 | * Return errno if it cannot successully install probes | |
1135 | * else return 0 (success) | |
1136 | */ | |
38e967ae | 1137 | static int __uprobe_register(struct inode *inode, loff_t offset, |
1cc33161 | 1138 | loff_t ref_ctr_offset, struct uprobe_consumer *uc) |
2b144498 SD |
1139 | { |
1140 | struct uprobe *uprobe; | |
7b2d81d4 | 1141 | int ret; |
2b144498 | 1142 | |
ea024870 AA |
1143 | /* Uprobe must have at least one set consumer */ |
1144 | if (!uc->handler && !uc->ret_handler) | |
1145 | return -EINVAL; | |
1146 | ||
40814f68 | 1147 | /* copy_insn() uses read_mapping_page() or shmem_read_mapping_page() */ |
5efe7448 | 1148 | if (!inode->i_mapping->a_ops->read_folio && |
5efe7448 | 1149 | !shmem_mapping(inode->i_mapping)) |
41ccba02 | 1150 | return -EIO; |
f0744af7 | 1151 | /* Racy, just to catch the obvious mistakes */ |
2b144498 | 1152 | if (offset > i_size_read(inode)) |
7b2d81d4 | 1153 | return -EINVAL; |
2b144498 | 1154 | |
013b2deb ON |
1155 | /* |
1156 | * This ensures that copy_from_page(), copy_to_page() and | |
1157 | * __update_ref_ctr() can't cross page boundary. | |
1158 | */ | |
1159 | if (!IS_ALIGNED(offset, UPROBE_SWBP_INSN_SIZE)) | |
1160 | return -EINVAL; | |
1161 | if (!IS_ALIGNED(ref_ctr_offset, sizeof(short))) | |
1162 | return -EINVAL; | |
1163 | ||
66d06dff | 1164 | retry: |
1cc33161 | 1165 | uprobe = alloc_uprobe(inode, offset, ref_ctr_offset); |
66d06dff ON |
1166 | if (!uprobe) |
1167 | return -ENOMEM; | |
22bad382 RB |
1168 | if (IS_ERR(uprobe)) |
1169 | return PTR_ERR(uprobe); | |
1170 | ||
66d06dff ON |
1171 | /* |
1172 | * We can race with uprobe_unregister()->delete_uprobe(). | |
1173 | * Check uprobe_is_active() and retry if it is false. | |
1174 | */ | |
1175 | down_write(&uprobe->register_rwsem); | |
1176 | ret = -EAGAIN; | |
1177 | if (likely(uprobe_is_active(uprobe))) { | |
38e967ae RB |
1178 | consumer_add(uprobe, uc); |
1179 | ret = register_for_each_vma(uprobe, uc); | |
9a98e03c | 1180 | if (ret) |
04aab9b2 | 1181 | __uprobe_unregister(uprobe, uc); |
2b144498 | 1182 | } |
66d06dff ON |
1183 | up_write(&uprobe->register_rwsem); |
1184 | put_uprobe(uprobe); | |
2b144498 | 1185 | |
66d06dff ON |
1186 | if (unlikely(ret == -EAGAIN)) |
1187 | goto retry; | |
2b144498 SD |
1188 | return ret; |
1189 | } | |
38e967ae RB |
1190 | |
1191 | int uprobe_register(struct inode *inode, loff_t offset, | |
1192 | struct uprobe_consumer *uc) | |
1193 | { | |
1cc33161 | 1194 | return __uprobe_register(inode, offset, 0, uc); |
38e967ae | 1195 | } |
e8440c14 | 1196 | EXPORT_SYMBOL_GPL(uprobe_register); |
2b144498 | 1197 | |
1cc33161 RB |
1198 | int uprobe_register_refctr(struct inode *inode, loff_t offset, |
1199 | loff_t ref_ctr_offset, struct uprobe_consumer *uc) | |
1200 | { | |
1201 | return __uprobe_register(inode, offset, ref_ctr_offset, uc); | |
1202 | } | |
1203 | EXPORT_SYMBOL_GPL(uprobe_register_refctr); | |
1204 | ||
bdf8647c | 1205 | /* |
788faab7 | 1206 | * uprobe_apply - unregister an already registered probe. |
bdf8647c ON |
1207 | * @inode: the file in which the probe has to be removed. |
1208 | * @offset: offset from the start of the file. | |
1209 | * @uc: consumer which wants to add more or remove some breakpoints | |
1210 | * @add: add or remove the breakpoints | |
1211 | */ | |
1212 | int uprobe_apply(struct inode *inode, loff_t offset, | |
1213 | struct uprobe_consumer *uc, bool add) | |
1214 | { | |
1215 | struct uprobe *uprobe; | |
1216 | struct uprobe_consumer *con; | |
1217 | int ret = -ENOENT; | |
1218 | ||
1219 | uprobe = find_uprobe(inode, offset); | |
06d07139 | 1220 | if (WARN_ON(!uprobe)) |
bdf8647c ON |
1221 | return ret; |
1222 | ||
1223 | down_write(&uprobe->register_rwsem); | |
1224 | for (con = uprobe->consumers; con && con != uc ; con = con->next) | |
1225 | ; | |
1226 | if (con) | |
1227 | ret = register_for_each_vma(uprobe, add ? uc : NULL); | |
1228 | up_write(&uprobe->register_rwsem); | |
1229 | put_uprobe(uprobe); | |
1230 | ||
1231 | return ret; | |
1232 | } | |
1233 | ||
da1816b1 ON |
1234 | static int unapply_uprobe(struct uprobe *uprobe, struct mm_struct *mm) |
1235 | { | |
fcb72a58 | 1236 | VMA_ITERATOR(vmi, mm, 0); |
da1816b1 ON |
1237 | struct vm_area_struct *vma; |
1238 | int err = 0; | |
1239 | ||
d8ed45c5 | 1240 | mmap_read_lock(mm); |
fcb72a58 | 1241 | for_each_vma(vmi, vma) { |
da1816b1 ON |
1242 | unsigned long vaddr; |
1243 | loff_t offset; | |
1244 | ||
1245 | if (!valid_vma(vma, false) || | |
f281769e | 1246 | file_inode(vma->vm_file) != uprobe->inode) |
da1816b1 ON |
1247 | continue; |
1248 | ||
1249 | offset = (loff_t)vma->vm_pgoff << PAGE_SHIFT; | |
1250 | if (uprobe->offset < offset || | |
1251 | uprobe->offset >= offset + vma->vm_end - vma->vm_start) | |
1252 | continue; | |
1253 | ||
1254 | vaddr = offset_to_vaddr(vma, uprobe->offset); | |
1255 | err |= remove_breakpoint(uprobe, mm, vaddr); | |
1256 | } | |
d8ed45c5 | 1257 | mmap_read_unlock(mm); |
da1816b1 ON |
1258 | |
1259 | return err; | |
1260 | } | |
1261 | ||
891c3970 ON |
1262 | static struct rb_node * |
1263 | find_node_in_range(struct inode *inode, loff_t min, loff_t max) | |
2b144498 | 1264 | { |
2b144498 | 1265 | struct rb_node *n = uprobes_tree.rb_node; |
2b144498 SD |
1266 | |
1267 | while (n) { | |
891c3970 | 1268 | struct uprobe *u = rb_entry(n, struct uprobe, rb_node); |
2b144498 | 1269 | |
891c3970 | 1270 | if (inode < u->inode) { |
2b144498 | 1271 | n = n->rb_left; |
891c3970 | 1272 | } else if (inode > u->inode) { |
2b144498 | 1273 | n = n->rb_right; |
891c3970 ON |
1274 | } else { |
1275 | if (max < u->offset) | |
1276 | n = n->rb_left; | |
1277 | else if (min > u->offset) | |
1278 | n = n->rb_right; | |
1279 | else | |
1280 | break; | |
1281 | } | |
2b144498 | 1282 | } |
7b2d81d4 | 1283 | |
891c3970 | 1284 | return n; |
2b144498 SD |
1285 | } |
1286 | ||
1287 | /* | |
891c3970 | 1288 | * For a given range in vma, build a list of probes that need to be inserted. |
2b144498 | 1289 | */ |
891c3970 ON |
1290 | static void build_probe_list(struct inode *inode, |
1291 | struct vm_area_struct *vma, | |
1292 | unsigned long start, unsigned long end, | |
1293 | struct list_head *head) | |
2b144498 | 1294 | { |
891c3970 | 1295 | loff_t min, max; |
891c3970 ON |
1296 | struct rb_node *n, *t; |
1297 | struct uprobe *u; | |
7b2d81d4 | 1298 | |
891c3970 | 1299 | INIT_LIST_HEAD(head); |
cb113b47 | 1300 | min = vaddr_to_offset(vma, start); |
891c3970 | 1301 | max = min + (end - start) - 1; |
2b144498 | 1302 | |
6f47caa0 | 1303 | spin_lock(&uprobes_treelock); |
891c3970 ON |
1304 | n = find_node_in_range(inode, min, max); |
1305 | if (n) { | |
1306 | for (t = n; t; t = rb_prev(t)) { | |
1307 | u = rb_entry(t, struct uprobe, rb_node); | |
1308 | if (u->inode != inode || u->offset < min) | |
1309 | break; | |
1310 | list_add(&u->pending_list, head); | |
f231722a | 1311 | get_uprobe(u); |
891c3970 ON |
1312 | } |
1313 | for (t = n; (t = rb_next(t)); ) { | |
1314 | u = rb_entry(t, struct uprobe, rb_node); | |
1315 | if (u->inode != inode || u->offset > max) | |
1316 | break; | |
1317 | list_add(&u->pending_list, head); | |
f231722a | 1318 | get_uprobe(u); |
891c3970 | 1319 | } |
2b144498 | 1320 | } |
6f47caa0 | 1321 | spin_unlock(&uprobes_treelock); |
2b144498 SD |
1322 | } |
1323 | ||
1cc33161 RB |
1324 | /* @vma contains reference counter, not the probed instruction. */ |
1325 | static int delayed_ref_ctr_inc(struct vm_area_struct *vma) | |
1326 | { | |
1327 | struct list_head *pos, *q; | |
1328 | struct delayed_uprobe *du; | |
1329 | unsigned long vaddr; | |
1330 | int ret = 0, err = 0; | |
1331 | ||
1332 | mutex_lock(&delayed_uprobe_lock); | |
1333 | list_for_each_safe(pos, q, &delayed_uprobe_list) { | |
1334 | du = list_entry(pos, struct delayed_uprobe, list); | |
1335 | ||
1336 | if (du->mm != vma->vm_mm || | |
1337 | !valid_ref_ctr_vma(du->uprobe, vma)) | |
1338 | continue; | |
1339 | ||
1340 | vaddr = offset_to_vaddr(vma, du->uprobe->ref_ctr_offset); | |
1341 | ret = __update_ref_ctr(vma->vm_mm, vaddr, 1); | |
1342 | if (ret) { | |
1343 | update_ref_ctr_warn(du->uprobe, vma->vm_mm, 1); | |
1344 | if (!err) | |
1345 | err = ret; | |
1346 | } | |
1347 | delayed_uprobe_delete(du); | |
1348 | } | |
1349 | mutex_unlock(&delayed_uprobe_lock); | |
1350 | return err; | |
1351 | } | |
1352 | ||
2b144498 | 1353 | /* |
0503ea8f | 1354 | * Called from mmap_region/vma_merge with mm->mmap_lock acquired. |
2b144498 | 1355 | * |
5e5be71a ON |
1356 | * Currently we ignore all errors and always return 0, the callers |
1357 | * can't handle the failure anyway. | |
2b144498 | 1358 | */ |
7b2d81d4 | 1359 | int uprobe_mmap(struct vm_area_struct *vma) |
2b144498 SD |
1360 | { |
1361 | struct list_head tmp_list; | |
665605a2 | 1362 | struct uprobe *uprobe, *u; |
2b144498 | 1363 | struct inode *inode; |
2b144498 | 1364 | |
1cc33161 RB |
1365 | if (no_uprobe_events()) |
1366 | return 0; | |
1367 | ||
1368 | if (vma->vm_file && | |
1369 | (vma->vm_flags & (VM_WRITE|VM_SHARED)) == VM_WRITE && | |
1370 | test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags)) | |
1371 | delayed_ref_ctr_inc(vma); | |
1372 | ||
1373 | if (!valid_vma(vma, true)) | |
7b2d81d4 | 1374 | return 0; |
2b144498 | 1375 | |
f281769e | 1376 | inode = file_inode(vma->vm_file); |
2b144498 | 1377 | if (!inode) |
7b2d81d4 | 1378 | return 0; |
2b144498 | 1379 | |
2b144498 | 1380 | mutex_lock(uprobes_mmap_hash(inode)); |
891c3970 | 1381 | build_probe_list(inode, vma, vma->vm_start, vma->vm_end, &tmp_list); |
806a98bd ON |
1382 | /* |
1383 | * We can race with uprobe_unregister(), this uprobe can be already | |
1384 | * removed. But in this case filter_chain() must return false, all | |
1385 | * consumers have gone away. | |
1386 | */ | |
665605a2 | 1387 | list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) { |
806a98bd | 1388 | if (!fatal_signal_pending(current) && |
8a7f2fa0 | 1389 | filter_chain(uprobe, UPROBE_FILTER_MMAP, vma->vm_mm)) { |
57683f72 | 1390 | unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset); |
5e5be71a | 1391 | install_breakpoint(uprobe, vma->vm_mm, vma, vaddr); |
2b144498 SD |
1392 | } |
1393 | put_uprobe(uprobe); | |
1394 | } | |
2b144498 SD |
1395 | mutex_unlock(uprobes_mmap_hash(inode)); |
1396 | ||
5e5be71a | 1397 | return 0; |
2b144498 SD |
1398 | } |
1399 | ||
9f68f672 ON |
1400 | static bool |
1401 | vma_has_uprobes(struct vm_area_struct *vma, unsigned long start, unsigned long end) | |
1402 | { | |
1403 | loff_t min, max; | |
1404 | struct inode *inode; | |
1405 | struct rb_node *n; | |
1406 | ||
f281769e | 1407 | inode = file_inode(vma->vm_file); |
9f68f672 ON |
1408 | |
1409 | min = vaddr_to_offset(vma, start); | |
1410 | max = min + (end - start) - 1; | |
1411 | ||
1412 | spin_lock(&uprobes_treelock); | |
1413 | n = find_node_in_range(inode, min, max); | |
1414 | spin_unlock(&uprobes_treelock); | |
1415 | ||
1416 | return !!n; | |
1417 | } | |
1418 | ||
682968e0 SD |
1419 | /* |
1420 | * Called in context of a munmap of a vma. | |
1421 | */ | |
cbc91f71 | 1422 | void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end) |
682968e0 | 1423 | { |
441f1eb7 | 1424 | if (no_uprobe_events() || !valid_vma(vma, false)) |
682968e0 SD |
1425 | return; |
1426 | ||
2fd611a9 ON |
1427 | if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */ |
1428 | return; | |
1429 | ||
9f68f672 ON |
1430 | if (!test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags) || |
1431 | test_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags)) | |
f8ac4ec9 ON |
1432 | return; |
1433 | ||
9f68f672 ON |
1434 | if (vma_has_uprobes(vma, start, end)) |
1435 | set_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags); | |
682968e0 SD |
1436 | } |
1437 | ||
d4b3b638 | 1438 | /* Slot allocation for XOL */ |
6441ec8b | 1439 | static int xol_add_vma(struct mm_struct *mm, struct xol_area *area) |
d4b3b638 | 1440 | { |
704bde3c ON |
1441 | struct vm_area_struct *vma; |
1442 | int ret; | |
d4b3b638 | 1443 | |
d8ed45c5 | 1444 | if (mmap_write_lock_killable(mm)) |
598fdc1d MH |
1445 | return -EINTR; |
1446 | ||
704bde3c ON |
1447 | if (mm->uprobes_state.xol_area) { |
1448 | ret = -EALREADY; | |
d4b3b638 | 1449 | goto fail; |
704bde3c | 1450 | } |
d4b3b638 | 1451 | |
af0d95af ON |
1452 | if (!area->vaddr) { |
1453 | /* Try to map as high as possible, this is only a hint. */ | |
1454 | area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE, | |
1455 | PAGE_SIZE, 0, 0); | |
ff68dac6 | 1456 | if (IS_ERR_VALUE(area->vaddr)) { |
af0d95af ON |
1457 | ret = area->vaddr; |
1458 | goto fail; | |
1459 | } | |
d4b3b638 SD |
1460 | } |
1461 | ||
704bde3c ON |
1462 | vma = _install_special_mapping(mm, area->vaddr, PAGE_SIZE, |
1463 | VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO, | |
1464 | &area->xol_mapping); | |
1465 | if (IS_ERR(vma)) { | |
1466 | ret = PTR_ERR(vma); | |
d4b3b638 | 1467 | goto fail; |
704bde3c | 1468 | } |
d4b3b638 | 1469 | |
704bde3c | 1470 | ret = 0; |
5c6338b4 PM |
1471 | /* pairs with get_xol_area() */ |
1472 | smp_store_release(&mm->uprobes_state.xol_area, area); /* ^^^ */ | |
c8a82538 | 1473 | fail: |
d8ed45c5 | 1474 | mmap_write_unlock(mm); |
d4b3b638 SD |
1475 | |
1476 | return ret; | |
1477 | } | |
1478 | ||
af0d95af | 1479 | static struct xol_area *__create_xol_area(unsigned long vaddr) |
d4b3b638 | 1480 | { |
9b545df8 | 1481 | struct mm_struct *mm = current->mm; |
e78aebfd | 1482 | uprobe_opcode_t insn = UPROBE_SWBP_INSN; |
6441ec8b | 1483 | struct xol_area *area; |
9b545df8 | 1484 | |
af0d95af | 1485 | area = kmalloc(sizeof(*area), GFP_KERNEL); |
d4b3b638 | 1486 | if (unlikely(!area)) |
c8a82538 | 1487 | goto out; |
d4b3b638 | 1488 | |
6396bb22 KC |
1489 | area->bitmap = kcalloc(BITS_TO_LONGS(UINSNS_PER_PAGE), sizeof(long), |
1490 | GFP_KERNEL); | |
d4b3b638 | 1491 | if (!area->bitmap) |
c8a82538 ON |
1492 | goto free_area; |
1493 | ||
704bde3c | 1494 | area->xol_mapping.name = "[uprobes]"; |
869ae761 | 1495 | area->xol_mapping.fault = NULL; |
704bde3c | 1496 | area->xol_mapping.pages = area->pages; |
f58bea2f ON |
1497 | area->pages[0] = alloc_page(GFP_HIGHUSER); |
1498 | if (!area->pages[0]) | |
c8a82538 | 1499 | goto free_bitmap; |
f58bea2f | 1500 | area->pages[1] = NULL; |
d4b3b638 | 1501 | |
af0d95af | 1502 | area->vaddr = vaddr; |
6441ec8b ON |
1503 | init_waitqueue_head(&area->wq); |
1504 | /* Reserve the 1st slot for get_trampoline_vaddr() */ | |
e78aebfd | 1505 | set_bit(0, area->bitmap); |
e78aebfd | 1506 | atomic_set(&area->slot_count, 1); |
297e765e | 1507 | arch_uprobe_copy_ixol(area->pages[0], 0, &insn, UPROBE_SWBP_INSN_SIZE); |
e78aebfd | 1508 | |
6441ec8b | 1509 | if (!xol_add_vma(mm, area)) |
d4b3b638 SD |
1510 | return area; |
1511 | ||
f58bea2f | 1512 | __free_page(area->pages[0]); |
c8a82538 | 1513 | free_bitmap: |
d4b3b638 | 1514 | kfree(area->bitmap); |
c8a82538 | 1515 | free_area: |
d4b3b638 | 1516 | kfree(area); |
c8a82538 | 1517 | out: |
6441ec8b ON |
1518 | return NULL; |
1519 | } | |
1520 | ||
1521 | /* | |
1522 | * get_xol_area - Allocate process's xol_area if necessary. | |
1523 | * This area will be used for storing instructions for execution out of line. | |
1524 | * | |
1525 | * Returns the allocated area or NULL. | |
1526 | */ | |
1527 | static struct xol_area *get_xol_area(void) | |
1528 | { | |
1529 | struct mm_struct *mm = current->mm; | |
1530 | struct xol_area *area; | |
1531 | ||
1532 | if (!mm->uprobes_state.xol_area) | |
af0d95af | 1533 | __create_xol_area(0); |
6441ec8b | 1534 | |
5c6338b4 PM |
1535 | /* Pairs with xol_add_vma() smp_store_release() */ |
1536 | area = READ_ONCE(mm->uprobes_state.xol_area); /* ^^^ */ | |
9b545df8 | 1537 | return area; |
d4b3b638 SD |
1538 | } |
1539 | ||
1540 | /* | |
1541 | * uprobe_clear_state - Free the area allocated for slots. | |
1542 | */ | |
1543 | void uprobe_clear_state(struct mm_struct *mm) | |
1544 | { | |
1545 | struct xol_area *area = mm->uprobes_state.xol_area; | |
1546 | ||
1cc33161 RB |
1547 | mutex_lock(&delayed_uprobe_lock); |
1548 | delayed_uprobe_remove(NULL, mm); | |
1549 | mutex_unlock(&delayed_uprobe_lock); | |
1550 | ||
d4b3b638 SD |
1551 | if (!area) |
1552 | return; | |
1553 | ||
f58bea2f | 1554 | put_page(area->pages[0]); |
d4b3b638 SD |
1555 | kfree(area->bitmap); |
1556 | kfree(area); | |
1557 | } | |
1558 | ||
32cdba1e ON |
1559 | void uprobe_start_dup_mmap(void) |
1560 | { | |
1561 | percpu_down_read(&dup_mmap_sem); | |
1562 | } | |
1563 | ||
1564 | void uprobe_end_dup_mmap(void) | |
1565 | { | |
1566 | percpu_up_read(&dup_mmap_sem); | |
1567 | } | |
1568 | ||
f8ac4ec9 ON |
1569 | void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm) |
1570 | { | |
9f68f672 | 1571 | if (test_bit(MMF_HAS_UPROBES, &oldmm->flags)) { |
f8ac4ec9 | 1572 | set_bit(MMF_HAS_UPROBES, &newmm->flags); |
9f68f672 ON |
1573 | /* unconditionally, dup_mmap() skips VM_DONTCOPY vmas */ |
1574 | set_bit(MMF_RECALC_UPROBES, &newmm->flags); | |
1575 | } | |
f8ac4ec9 ON |
1576 | } |
1577 | ||
d4b3b638 SD |
1578 | /* |
1579 | * - search for a free slot. | |
1580 | */ | |
1581 | static unsigned long xol_take_insn_slot(struct xol_area *area) | |
1582 | { | |
1583 | unsigned long slot_addr; | |
1584 | int slot_nr; | |
1585 | ||
1586 | do { | |
1587 | slot_nr = find_first_zero_bit(area->bitmap, UINSNS_PER_PAGE); | |
1588 | if (slot_nr < UINSNS_PER_PAGE) { | |
1589 | if (!test_and_set_bit(slot_nr, area->bitmap)) | |
1590 | break; | |
1591 | ||
1592 | slot_nr = UINSNS_PER_PAGE; | |
1593 | continue; | |
1594 | } | |
1595 | wait_event(area->wq, (atomic_read(&area->slot_count) < UINSNS_PER_PAGE)); | |
1596 | } while (slot_nr >= UINSNS_PER_PAGE); | |
1597 | ||
1598 | slot_addr = area->vaddr + (slot_nr * UPROBE_XOL_SLOT_BYTES); | |
1599 | atomic_inc(&area->slot_count); | |
1600 | ||
1601 | return slot_addr; | |
1602 | } | |
1603 | ||
1604 | /* | |
a6cb3f6d | 1605 | * xol_get_insn_slot - allocate a slot for xol. |
d4b3b638 SD |
1606 | * Returns the allocated slot address or 0. |
1607 | */ | |
a6cb3f6d | 1608 | static unsigned long xol_get_insn_slot(struct uprobe *uprobe) |
d4b3b638 SD |
1609 | { |
1610 | struct xol_area *area; | |
a6cb3f6d | 1611 | unsigned long xol_vaddr; |
d4b3b638 | 1612 | |
9b545df8 ON |
1613 | area = get_xol_area(); |
1614 | if (!area) | |
1615 | return 0; | |
d4b3b638 | 1616 | |
a6cb3f6d ON |
1617 | xol_vaddr = xol_take_insn_slot(area); |
1618 | if (unlikely(!xol_vaddr)) | |
d4b3b638 SD |
1619 | return 0; |
1620 | ||
f58bea2f | 1621 | arch_uprobe_copy_ixol(area->pages[0], xol_vaddr, |
72e6ae28 | 1622 | &uprobe->arch.ixol, sizeof(uprobe->arch.ixol)); |
d4b3b638 | 1623 | |
a6cb3f6d | 1624 | return xol_vaddr; |
d4b3b638 SD |
1625 | } |
1626 | ||
1627 | /* | |
1628 | * xol_free_insn_slot - If slot was earlier allocated by | |
1629 | * @xol_get_insn_slot(), make the slot available for | |
1630 | * subsequent requests. | |
1631 | */ | |
1632 | static void xol_free_insn_slot(struct task_struct *tsk) | |
1633 | { | |
1634 | struct xol_area *area; | |
1635 | unsigned long vma_end; | |
1636 | unsigned long slot_addr; | |
1637 | ||
1638 | if (!tsk->mm || !tsk->mm->uprobes_state.xol_area || !tsk->utask) | |
1639 | return; | |
1640 | ||
1641 | slot_addr = tsk->utask->xol_vaddr; | |
af4355e9 | 1642 | if (unlikely(!slot_addr)) |
d4b3b638 SD |
1643 | return; |
1644 | ||
1645 | area = tsk->mm->uprobes_state.xol_area; | |
1646 | vma_end = area->vaddr + PAGE_SIZE; | |
1647 | if (area->vaddr <= slot_addr && slot_addr < vma_end) { | |
1648 | unsigned long offset; | |
1649 | int slot_nr; | |
1650 | ||
1651 | offset = slot_addr - area->vaddr; | |
1652 | slot_nr = offset / UPROBE_XOL_SLOT_BYTES; | |
1653 | if (slot_nr >= UINSNS_PER_PAGE) | |
1654 | return; | |
1655 | ||
1656 | clear_bit(slot_nr, area->bitmap); | |
1657 | atomic_dec(&area->slot_count); | |
2a742ced | 1658 | smp_mb__after_atomic(); /* pairs with prepare_to_wait() */ |
d4b3b638 SD |
1659 | if (waitqueue_active(&area->wq)) |
1660 | wake_up(&area->wq); | |
1661 | ||
1662 | tsk->utask->xol_vaddr = 0; | |
1663 | } | |
1664 | } | |
1665 | ||
72e6ae28 VK |
1666 | void __weak arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr, |
1667 | void *src, unsigned long len) | |
1668 | { | |
1669 | /* Initialize the slot */ | |
1670 | copy_to_page(page, vaddr, src, len); | |
1671 | ||
1672 | /* | |
885f7f8e | 1673 | * We probably need flush_icache_user_page() but it needs vma. |
72e6ae28 VK |
1674 | * This should work on most of architectures by default. If |
1675 | * architecture needs to do something different it can define | |
1676 | * its own version of the function. | |
1677 | */ | |
1678 | flush_dcache_page(page); | |
1679 | } | |
1680 | ||
0326f5a9 SD |
1681 | /** |
1682 | * uprobe_get_swbp_addr - compute address of swbp given post-swbp regs | |
1683 | * @regs: Reflects the saved state of the task after it has hit a breakpoint | |
1684 | * instruction. | |
1685 | * Return the address of the breakpoint instruction. | |
1686 | */ | |
1687 | unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs) | |
1688 | { | |
1689 | return instruction_pointer(regs) - UPROBE_SWBP_INSN_SIZE; | |
1690 | } | |
1691 | ||
b02ef20a ON |
1692 | unsigned long uprobe_get_trap_addr(struct pt_regs *regs) |
1693 | { | |
1694 | struct uprobe_task *utask = current->utask; | |
1695 | ||
1696 | if (unlikely(utask && utask->active_uprobe)) | |
1697 | return utask->vaddr; | |
1698 | ||
1699 | return instruction_pointer(regs); | |
1700 | } | |
1701 | ||
2bb5e840 ON |
1702 | static struct return_instance *free_ret_instance(struct return_instance *ri) |
1703 | { | |
1704 | struct return_instance *next = ri->next; | |
1705 | put_uprobe(ri->uprobe); | |
1706 | kfree(ri); | |
1707 | return next; | |
1708 | } | |
1709 | ||
0326f5a9 SD |
1710 | /* |
1711 | * Called with no locks held. | |
788faab7 | 1712 | * Called in context of an exiting or an exec-ing thread. |
0326f5a9 SD |
1713 | */ |
1714 | void uprobe_free_utask(struct task_struct *t) | |
1715 | { | |
1716 | struct uprobe_task *utask = t->utask; | |
2bb5e840 | 1717 | struct return_instance *ri; |
0326f5a9 | 1718 | |
0326f5a9 SD |
1719 | if (!utask) |
1720 | return; | |
1721 | ||
1722 | if (utask->active_uprobe) | |
1723 | put_uprobe(utask->active_uprobe); | |
1724 | ||
0dfd0eb8 | 1725 | ri = utask->return_instances; |
2bb5e840 ON |
1726 | while (ri) |
1727 | ri = free_ret_instance(ri); | |
0dfd0eb8 | 1728 | |
d4b3b638 | 1729 | xol_free_insn_slot(t); |
0326f5a9 SD |
1730 | kfree(utask); |
1731 | t->utask = NULL; | |
1732 | } | |
1733 | ||
0326f5a9 | 1734 | /* |
c034f48e | 1735 | * Allocate a uprobe_task object for the task if necessary. |
5a2df662 | 1736 | * Called when the thread hits a breakpoint. |
0326f5a9 SD |
1737 | * |
1738 | * Returns: | |
1739 | * - pointer to new uprobe_task on success | |
1740 | * - NULL otherwise | |
1741 | */ | |
5a2df662 | 1742 | static struct uprobe_task *get_utask(void) |
0326f5a9 | 1743 | { |
5a2df662 ON |
1744 | if (!current->utask) |
1745 | current->utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL); | |
1746 | return current->utask; | |
0326f5a9 SD |
1747 | } |
1748 | ||
248d3a7b ON |
1749 | static int dup_utask(struct task_struct *t, struct uprobe_task *o_utask) |
1750 | { | |
1751 | struct uprobe_task *n_utask; | |
1752 | struct return_instance **p, *o, *n; | |
1753 | ||
1754 | n_utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL); | |
1755 | if (!n_utask) | |
1756 | return -ENOMEM; | |
1757 | t->utask = n_utask; | |
1758 | ||
1759 | p = &n_utask->return_instances; | |
1760 | for (o = o_utask->return_instances; o; o = o->next) { | |
1761 | n = kmalloc(sizeof(struct return_instance), GFP_KERNEL); | |
1762 | if (!n) | |
1763 | return -ENOMEM; | |
1764 | ||
1765 | *n = *o; | |
f231722a | 1766 | get_uprobe(n->uprobe); |
248d3a7b ON |
1767 | n->next = NULL; |
1768 | ||
1769 | *p = n; | |
1770 | p = &n->next; | |
1771 | n_utask->depth++; | |
1772 | } | |
1773 | ||
1774 | return 0; | |
1775 | } | |
1776 | ||
1777 | static void uprobe_warn(struct task_struct *t, const char *msg) | |
1778 | { | |
1779 | pr_warn("uprobe: %s:%d failed to %s\n", | |
1780 | current->comm, current->pid, msg); | |
1781 | } | |
1782 | ||
aa59c53f ON |
1783 | static void dup_xol_work(struct callback_head *work) |
1784 | { | |
aa59c53f ON |
1785 | if (current->flags & PF_EXITING) |
1786 | return; | |
1787 | ||
598fdc1d MH |
1788 | if (!__create_xol_area(current->utask->dup_xol_addr) && |
1789 | !fatal_signal_pending(current)) | |
aa59c53f ON |
1790 | uprobe_warn(current, "dup xol area"); |
1791 | } | |
1792 | ||
b68e0749 ON |
1793 | /* |
1794 | * Called in context of a new clone/fork from copy_process. | |
1795 | */ | |
3ab67966 | 1796 | void uprobe_copy_process(struct task_struct *t, unsigned long flags) |
b68e0749 | 1797 | { |
248d3a7b ON |
1798 | struct uprobe_task *utask = current->utask; |
1799 | struct mm_struct *mm = current->mm; | |
aa59c53f | 1800 | struct xol_area *area; |
248d3a7b | 1801 | |
b68e0749 | 1802 | t->utask = NULL; |
248d3a7b | 1803 | |
3ab67966 ON |
1804 | if (!utask || !utask->return_instances) |
1805 | return; | |
1806 | ||
1807 | if (mm == t->mm && !(flags & CLONE_VFORK)) | |
248d3a7b ON |
1808 | return; |
1809 | ||
1810 | if (dup_utask(t, utask)) | |
1811 | return uprobe_warn(t, "dup ret instances"); | |
aa59c53f ON |
1812 | |
1813 | /* The task can fork() after dup_xol_work() fails */ | |
1814 | area = mm->uprobes_state.xol_area; | |
1815 | if (!area) | |
1816 | return uprobe_warn(t, "dup xol area"); | |
1817 | ||
3ab67966 ON |
1818 | if (mm == t->mm) |
1819 | return; | |
1820 | ||
32473431 ON |
1821 | t->utask->dup_xol_addr = area->vaddr; |
1822 | init_task_work(&t->utask->dup_xol_work, dup_xol_work); | |
91989c70 | 1823 | task_work_add(t, &t->utask->dup_xol_work, TWA_RESUME); |
b68e0749 ON |
1824 | } |
1825 | ||
e78aebfd AA |
1826 | /* |
1827 | * Current area->vaddr notion assume the trampoline address is always | |
1828 | * equal area->vaddr. | |
1829 | * | |
1830 | * Returns -1 in case the xol_area is not allocated. | |
1831 | */ | |
1832 | static unsigned long get_trampoline_vaddr(void) | |
1833 | { | |
1834 | struct xol_area *area; | |
1835 | unsigned long trampoline_vaddr = -1; | |
1836 | ||
5c6338b4 PM |
1837 | /* Pairs with xol_add_vma() smp_store_release() */ |
1838 | area = READ_ONCE(current->mm->uprobes_state.xol_area); /* ^^^ */ | |
e78aebfd AA |
1839 | if (area) |
1840 | trampoline_vaddr = area->vaddr; | |
1841 | ||
1842 | return trampoline_vaddr; | |
1843 | } | |
1844 | ||
db087ef6 ON |
1845 | static void cleanup_return_instances(struct uprobe_task *utask, bool chained, |
1846 | struct pt_regs *regs) | |
a5b7e1a8 ON |
1847 | { |
1848 | struct return_instance *ri = utask->return_instances; | |
db087ef6 | 1849 | enum rp_check ctx = chained ? RP_CHECK_CHAIN_CALL : RP_CHECK_CALL; |
86dcb702 ON |
1850 | |
1851 | while (ri && !arch_uretprobe_is_alive(ri, ctx, regs)) { | |
a5b7e1a8 ON |
1852 | ri = free_ret_instance(ri); |
1853 | utask->depth--; | |
1854 | } | |
1855 | utask->return_instances = ri; | |
1856 | } | |
1857 | ||
0dfd0eb8 AA |
1858 | static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs) |
1859 | { | |
1860 | struct return_instance *ri; | |
1861 | struct uprobe_task *utask; | |
1862 | unsigned long orig_ret_vaddr, trampoline_vaddr; | |
db087ef6 | 1863 | bool chained; |
0dfd0eb8 AA |
1864 | |
1865 | if (!get_xol_area()) | |
1866 | return; | |
1867 | ||
1868 | utask = get_utask(); | |
1869 | if (!utask) | |
1870 | return; | |
1871 | ||
ded49c55 AA |
1872 | if (utask->depth >= MAX_URETPROBE_DEPTH) { |
1873 | printk_ratelimited(KERN_INFO "uprobe: omit uretprobe due to" | |
1874 | " nestedness limit pid/tgid=%d/%d\n", | |
1875 | current->pid, current->tgid); | |
1876 | return; | |
1877 | } | |
1878 | ||
6c58d0e4 | 1879 | ri = kmalloc(sizeof(struct return_instance), GFP_KERNEL); |
0dfd0eb8 | 1880 | if (!ri) |
6c58d0e4 | 1881 | return; |
0dfd0eb8 AA |
1882 | |
1883 | trampoline_vaddr = get_trampoline_vaddr(); | |
1884 | orig_ret_vaddr = arch_uretprobe_hijack_return_addr(trampoline_vaddr, regs); | |
1885 | if (orig_ret_vaddr == -1) | |
1886 | goto fail; | |
1887 | ||
a5b7e1a8 | 1888 | /* drop the entries invalidated by longjmp() */ |
db087ef6 ON |
1889 | chained = (orig_ret_vaddr == trampoline_vaddr); |
1890 | cleanup_return_instances(utask, chained, regs); | |
a5b7e1a8 | 1891 | |
0dfd0eb8 AA |
1892 | /* |
1893 | * We don't want to keep trampoline address in stack, rather keep the | |
1894 | * original return address of first caller thru all the consequent | |
1895 | * instances. This also makes breakpoint unwrapping easier. | |
1896 | */ | |
db087ef6 | 1897 | if (chained) { |
0dfd0eb8 AA |
1898 | if (!utask->return_instances) { |
1899 | /* | |
1900 | * This situation is not possible. Likely we have an | |
1901 | * attack from user-space. | |
1902 | */ | |
6c58d0e4 | 1903 | uprobe_warn(current, "handle tail call"); |
0dfd0eb8 AA |
1904 | goto fail; |
1905 | } | |
0dfd0eb8 AA |
1906 | orig_ret_vaddr = utask->return_instances->orig_ret_vaddr; |
1907 | } | |
1908 | ||
f231722a | 1909 | ri->uprobe = get_uprobe(uprobe); |
0dfd0eb8 | 1910 | ri->func = instruction_pointer(regs); |
7b868e48 | 1911 | ri->stack = user_stack_pointer(regs); |
0dfd0eb8 AA |
1912 | ri->orig_ret_vaddr = orig_ret_vaddr; |
1913 | ri->chained = chained; | |
1914 | ||
ded49c55 | 1915 | utask->depth++; |
0dfd0eb8 AA |
1916 | ri->next = utask->return_instances; |
1917 | utask->return_instances = ri; | |
1918 | ||
1919 | return; | |
0dfd0eb8 AA |
1920 | fail: |
1921 | kfree(ri); | |
1922 | } | |
1923 | ||
0326f5a9 SD |
1924 | /* Prepare to single-step probed instruction out of line. */ |
1925 | static int | |
a6cb3f6d | 1926 | pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long bp_vaddr) |
0326f5a9 | 1927 | { |
a6cb3f6d ON |
1928 | struct uprobe_task *utask; |
1929 | unsigned long xol_vaddr; | |
aba51024 | 1930 | int err; |
a6cb3f6d | 1931 | |
608e7427 ON |
1932 | utask = get_utask(); |
1933 | if (!utask) | |
1934 | return -ENOMEM; | |
a6cb3f6d ON |
1935 | |
1936 | xol_vaddr = xol_get_insn_slot(uprobe); | |
1937 | if (!xol_vaddr) | |
1938 | return -ENOMEM; | |
1939 | ||
1940 | utask->xol_vaddr = xol_vaddr; | |
1941 | utask->vaddr = bp_vaddr; | |
d4b3b638 | 1942 | |
aba51024 ON |
1943 | err = arch_uprobe_pre_xol(&uprobe->arch, regs); |
1944 | if (unlikely(err)) { | |
1945 | xol_free_insn_slot(current); | |
1946 | return err; | |
1947 | } | |
1948 | ||
608e7427 ON |
1949 | utask->active_uprobe = uprobe; |
1950 | utask->state = UTASK_SSTEP; | |
aba51024 | 1951 | return 0; |
0326f5a9 SD |
1952 | } |
1953 | ||
1954 | /* | |
1955 | * If we are singlestepping, then ensure this thread is not connected to | |
1956 | * non-fatal signals until completion of singlestep. When xol insn itself | |
1957 | * triggers the signal, restart the original insn even if the task is | |
1958 | * already SIGKILL'ed (since coredump should report the correct ip). This | |
1959 | * is even more important if the task has a handler for SIGSEGV/etc, The | |
1960 | * _same_ instruction should be repeated again after return from the signal | |
1961 | * handler, and SSTEP can never finish in this case. | |
1962 | */ | |
1963 | bool uprobe_deny_signal(void) | |
1964 | { | |
1965 | struct task_struct *t = current; | |
1966 | struct uprobe_task *utask = t->utask; | |
1967 | ||
1968 | if (likely(!utask || !utask->active_uprobe)) | |
1969 | return false; | |
1970 | ||
1971 | WARN_ON_ONCE(utask->state != UTASK_SSTEP); | |
1972 | ||
5c251e9d | 1973 | if (task_sigpending(t)) { |
0326f5a9 SD |
1974 | spin_lock_irq(&t->sighand->siglock); |
1975 | clear_tsk_thread_flag(t, TIF_SIGPENDING); | |
1976 | spin_unlock_irq(&t->sighand->siglock); | |
1977 | ||
1978 | if (__fatal_signal_pending(t) || arch_uprobe_xol_was_trapped(t)) { | |
1979 | utask->state = UTASK_SSTEP_TRAPPED; | |
1980 | set_tsk_thread_flag(t, TIF_UPROBE); | |
0326f5a9 SD |
1981 | } |
1982 | } | |
1983 | ||
1984 | return true; | |
1985 | } | |
1986 | ||
499a4f3e ON |
1987 | static void mmf_recalc_uprobes(struct mm_struct *mm) |
1988 | { | |
fcb72a58 | 1989 | VMA_ITERATOR(vmi, mm, 0); |
499a4f3e ON |
1990 | struct vm_area_struct *vma; |
1991 | ||
fcb72a58 | 1992 | for_each_vma(vmi, vma) { |
499a4f3e ON |
1993 | if (!valid_vma(vma, false)) |
1994 | continue; | |
1995 | /* | |
1996 | * This is not strictly accurate, we can race with | |
1997 | * uprobe_unregister() and see the already removed | |
1998 | * uprobe if delete_uprobe() was not yet called. | |
63633cbf | 1999 | * Or this uprobe can be filtered out. |
499a4f3e ON |
2000 | */ |
2001 | if (vma_has_uprobes(vma, vma->vm_start, vma->vm_end)) | |
2002 | return; | |
2003 | } | |
2004 | ||
2005 | clear_bit(MMF_HAS_UPROBES, &mm->flags); | |
2006 | } | |
2007 | ||
0908ad6e | 2008 | static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr) |
ec75fba9 ON |
2009 | { |
2010 | struct page *page; | |
2011 | uprobe_opcode_t opcode; | |
2012 | int result; | |
2013 | ||
013b2deb ON |
2014 | if (WARN_ON_ONCE(!IS_ALIGNED(vaddr, UPROBE_SWBP_INSN_SIZE))) |
2015 | return -EINVAL; | |
2016 | ||
ec75fba9 | 2017 | pagefault_disable(); |
bd28b145 | 2018 | result = __get_user(opcode, (uprobe_opcode_t __user *)vaddr); |
ec75fba9 ON |
2019 | pagefault_enable(); |
2020 | ||
2021 | if (likely(result == 0)) | |
2022 | goto out; | |
2023 | ||
1e987790 DH |
2024 | /* |
2025 | * The NULL 'tsk' here ensures that any faults that occur here | |
2026 | * will not be accounted to the task. 'mm' *is* current->mm, | |
2027 | * but we treat this as a 'remote' access since it is | |
2028 | * essentially a kernel access to the memory. | |
2029 | */ | |
64019a2e | 2030 | result = get_user_pages_remote(mm, vaddr, 1, FOLL_FORCE, &page, |
5b56d49f | 2031 | NULL, NULL); |
ec75fba9 ON |
2032 | if (result < 0) |
2033 | return result; | |
2034 | ||
ab0d805c | 2035 | copy_from_page(page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE); |
ec75fba9 ON |
2036 | put_page(page); |
2037 | out: | |
0908ad6e AM |
2038 | /* This needs to return true for any variant of the trap insn */ |
2039 | return is_trap_insn(&opcode); | |
ec75fba9 ON |
2040 | } |
2041 | ||
d790d346 | 2042 | static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp) |
0326f5a9 | 2043 | { |
3a9ea052 ON |
2044 | struct mm_struct *mm = current->mm; |
2045 | struct uprobe *uprobe = NULL; | |
0326f5a9 | 2046 | struct vm_area_struct *vma; |
0326f5a9 | 2047 | |
d8ed45c5 | 2048 | mmap_read_lock(mm); |
9016dded LH |
2049 | vma = vma_lookup(mm, bp_vaddr); |
2050 | if (vma) { | |
3a9ea052 | 2051 | if (valid_vma(vma, false)) { |
f281769e | 2052 | struct inode *inode = file_inode(vma->vm_file); |
cb113b47 | 2053 | loff_t offset = vaddr_to_offset(vma, bp_vaddr); |
0326f5a9 | 2054 | |
3a9ea052 ON |
2055 | uprobe = find_uprobe(inode, offset); |
2056 | } | |
d790d346 ON |
2057 | |
2058 | if (!uprobe) | |
0908ad6e | 2059 | *is_swbp = is_trap_at_addr(mm, bp_vaddr); |
d790d346 ON |
2060 | } else { |
2061 | *is_swbp = -EFAULT; | |
0326f5a9 | 2062 | } |
499a4f3e ON |
2063 | |
2064 | if (!uprobe && test_and_clear_bit(MMF_RECALC_UPROBES, &mm->flags)) | |
2065 | mmf_recalc_uprobes(mm); | |
d8ed45c5 | 2066 | mmap_read_unlock(mm); |
0326f5a9 | 2067 | |
3a9ea052 ON |
2068 | return uprobe; |
2069 | } | |
2070 | ||
da1816b1 ON |
2071 | static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs) |
2072 | { | |
2073 | struct uprobe_consumer *uc; | |
2074 | int remove = UPROBE_HANDLER_REMOVE; | |
0dfd0eb8 | 2075 | bool need_prep = false; /* prepare return uprobe, when needed */ |
da1816b1 ON |
2076 | |
2077 | down_read(&uprobe->register_rwsem); | |
2078 | for (uc = uprobe->consumers; uc; uc = uc->next) { | |
ea024870 | 2079 | int rc = 0; |
da1816b1 | 2080 | |
ea024870 AA |
2081 | if (uc->handler) { |
2082 | rc = uc->handler(uc, regs); | |
2083 | WARN(rc & ~UPROBE_HANDLER_MASK, | |
d75f773c | 2084 | "bad rc=0x%x from %ps()\n", rc, uc->handler); |
ea024870 | 2085 | } |
0dfd0eb8 AA |
2086 | |
2087 | if (uc->ret_handler) | |
2088 | need_prep = true; | |
2089 | ||
da1816b1 ON |
2090 | remove &= rc; |
2091 | } | |
2092 | ||
0dfd0eb8 AA |
2093 | if (need_prep && !remove) |
2094 | prepare_uretprobe(uprobe, regs); /* put bp at return */ | |
2095 | ||
da1816b1 ON |
2096 | if (remove && uprobe->consumers) { |
2097 | WARN_ON(!uprobe_is_active(uprobe)); | |
2098 | unapply_uprobe(uprobe, current->mm); | |
2099 | } | |
2100 | up_read(&uprobe->register_rwsem); | |
2101 | } | |
2102 | ||
fec8898d AA |
2103 | static void |
2104 | handle_uretprobe_chain(struct return_instance *ri, struct pt_regs *regs) | |
2105 | { | |
2106 | struct uprobe *uprobe = ri->uprobe; | |
2107 | struct uprobe_consumer *uc; | |
2108 | ||
2109 | down_read(&uprobe->register_rwsem); | |
2110 | for (uc = uprobe->consumers; uc; uc = uc->next) { | |
2111 | if (uc->ret_handler) | |
2112 | uc->ret_handler(uc, ri->func, regs); | |
2113 | } | |
2114 | up_read(&uprobe->register_rwsem); | |
2115 | } | |
2116 | ||
a83cfeb9 ON |
2117 | static struct return_instance *find_next_ret_chain(struct return_instance *ri) |
2118 | { | |
2119 | bool chained; | |
2120 | ||
2121 | do { | |
2122 | chained = ri->chained; | |
2123 | ri = ri->next; /* can't be NULL if chained */ | |
2124 | } while (chained); | |
2125 | ||
2126 | return ri; | |
2127 | } | |
2128 | ||
0b5256c7 | 2129 | static void handle_trampoline(struct pt_regs *regs) |
fec8898d AA |
2130 | { |
2131 | struct uprobe_task *utask; | |
a83cfeb9 | 2132 | struct return_instance *ri, *next; |
5eeb50de | 2133 | bool valid; |
fec8898d AA |
2134 | |
2135 | utask = current->utask; | |
2136 | if (!utask) | |
0b5256c7 | 2137 | goto sigill; |
fec8898d AA |
2138 | |
2139 | ri = utask->return_instances; | |
2140 | if (!ri) | |
0b5256c7 | 2141 | goto sigill; |
fec8898d | 2142 | |
a83cfeb9 | 2143 | do { |
5eeb50de ON |
2144 | /* |
2145 | * We should throw out the frames invalidated by longjmp(). | |
2146 | * If this chain is valid, then the next one should be alive | |
2147 | * or NULL; the latter case means that nobody but ri->func | |
2148 | * could hit this trampoline on return. TODO: sigaltstack(). | |
2149 | */ | |
2150 | next = find_next_ret_chain(ri); | |
86dcb702 | 2151 | valid = !next || arch_uretprobe_is_alive(next, RP_CHECK_RET, regs); |
5eeb50de ON |
2152 | |
2153 | instruction_pointer_set(regs, ri->orig_ret_vaddr); | |
2154 | do { | |
2155 | if (valid) | |
2156 | handle_uretprobe_chain(ri, regs); | |
2157 | ri = free_ret_instance(ri); | |
2158 | utask->depth--; | |
2159 | } while (ri != next); | |
2160 | } while (!valid); | |
fec8898d AA |
2161 | |
2162 | utask->return_instances = ri; | |
0b5256c7 ON |
2163 | return; |
2164 | ||
2165 | sigill: | |
2166 | uprobe_warn(current, "handle uretprobe, sending SIGILL."); | |
3cf5d076 | 2167 | force_sig(SIGILL); |
fec8898d | 2168 | |
fec8898d AA |
2169 | } |
2170 | ||
6fe50a28 DL |
2171 | bool __weak arch_uprobe_ignore(struct arch_uprobe *aup, struct pt_regs *regs) |
2172 | { | |
2173 | return false; | |
2174 | } | |
2175 | ||
86dcb702 ON |
2176 | bool __weak arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx, |
2177 | struct pt_regs *regs) | |
97da8976 ON |
2178 | { |
2179 | return true; | |
2180 | } | |
2181 | ||
3a9ea052 ON |
2182 | /* |
2183 | * Run handler and ask thread to singlestep. | |
2184 | * Ensure all non-fatal signals cannot interrupt thread while it singlesteps. | |
2185 | */ | |
2186 | static void handle_swbp(struct pt_regs *regs) | |
2187 | { | |
3a9ea052 ON |
2188 | struct uprobe *uprobe; |
2189 | unsigned long bp_vaddr; | |
3f649ab7 | 2190 | int is_swbp; |
3a9ea052 ON |
2191 | |
2192 | bp_vaddr = uprobe_get_swbp_addr(regs); | |
0b5256c7 ON |
2193 | if (bp_vaddr == get_trampoline_vaddr()) |
2194 | return handle_trampoline(regs); | |
fec8898d AA |
2195 | |
2196 | uprobe = find_active_uprobe(bp_vaddr, &is_swbp); | |
0326f5a9 | 2197 | if (!uprobe) { |
56bb4cf6 ON |
2198 | if (is_swbp > 0) { |
2199 | /* No matching uprobe; signal SIGTRAP. */ | |
fe5ed7ab | 2200 | force_sig(SIGTRAP); |
56bb4cf6 ON |
2201 | } else { |
2202 | /* | |
2203 | * Either we raced with uprobe_unregister() or we can't | |
2204 | * access this memory. The latter is only possible if | |
2205 | * another thread plays with our ->mm. In both cases | |
2206 | * we can simply restart. If this vma was unmapped we | |
2207 | * can pretend this insn was not executed yet and get | |
2208 | * the (correct) SIGSEGV after restart. | |
2209 | */ | |
2210 | instruction_pointer_set(regs, bp_vaddr); | |
2211 | } | |
0326f5a9 SD |
2212 | return; |
2213 | } | |
74e59dfc ON |
2214 | |
2215 | /* change it in advance for ->handler() and restart */ | |
2216 | instruction_pointer_set(regs, bp_vaddr); | |
2217 | ||
142b18dd ON |
2218 | /* |
2219 | * TODO: move copy_insn/etc into _register and remove this hack. | |
2220 | * After we hit the bp, _unregister + _register can install the | |
2221 | * new and not-yet-analyzed uprobe at the same address, restart. | |
2222 | */ | |
71434f2f | 2223 | if (unlikely(!test_bit(UPROBE_COPY_INSN, &uprobe->flags))) |
74e59dfc | 2224 | goto out; |
0326f5a9 | 2225 | |
09d3f015 AP |
2226 | /* |
2227 | * Pairs with the smp_wmb() in prepare_uprobe(). | |
2228 | * | |
2229 | * Guarantees that if we see the UPROBE_COPY_INSN bit set, then | |
2230 | * we must also see the stores to &uprobe->arch performed by the | |
2231 | * prepare_uprobe() call. | |
2232 | */ | |
2233 | smp_rmb(); | |
2234 | ||
72fd293a ON |
2235 | /* Tracing handlers use ->utask to communicate with fetch methods */ |
2236 | if (!get_utask()) | |
2237 | goto out; | |
2238 | ||
6fe50a28 DL |
2239 | if (arch_uprobe_ignore(&uprobe->arch, regs)) |
2240 | goto out; | |
2241 | ||
0326f5a9 | 2242 | handler_chain(uprobe, regs); |
6fe50a28 | 2243 | |
8a6b1732 | 2244 | if (arch_uprobe_skip_sstep(&uprobe->arch, regs)) |
0578a970 | 2245 | goto out; |
0326f5a9 | 2246 | |
608e7427 | 2247 | if (!pre_ssout(uprobe, regs, bp_vaddr)) |
0326f5a9 | 2248 | return; |
0326f5a9 | 2249 | |
8a6b1732 | 2250 | /* arch_uprobe_skip_sstep() succeeded, or restart if can't singlestep */ |
0578a970 | 2251 | out: |
8bd87445 | 2252 | put_uprobe(uprobe); |
0326f5a9 SD |
2253 | } |
2254 | ||
2255 | /* | |
2256 | * Perform required fix-ups and disable singlestep. | |
2257 | * Allow pending signals to take effect. | |
2258 | */ | |
2259 | static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs) | |
2260 | { | |
2261 | struct uprobe *uprobe; | |
014940ba | 2262 | int err = 0; |
0326f5a9 SD |
2263 | |
2264 | uprobe = utask->active_uprobe; | |
2265 | if (utask->state == UTASK_SSTEP_ACK) | |
014940ba | 2266 | err = arch_uprobe_post_xol(&uprobe->arch, regs); |
0326f5a9 SD |
2267 | else if (utask->state == UTASK_SSTEP_TRAPPED) |
2268 | arch_uprobe_abort_xol(&uprobe->arch, regs); | |
2269 | else | |
2270 | WARN_ON_ONCE(1); | |
2271 | ||
2272 | put_uprobe(uprobe); | |
2273 | utask->active_uprobe = NULL; | |
2274 | utask->state = UTASK_RUNNING; | |
d4b3b638 | 2275 | xol_free_insn_slot(current); |
0326f5a9 SD |
2276 | |
2277 | spin_lock_irq(¤t->sighand->siglock); | |
2278 | recalc_sigpending(); /* see uprobe_deny_signal() */ | |
2279 | spin_unlock_irq(¤t->sighand->siglock); | |
014940ba ON |
2280 | |
2281 | if (unlikely(err)) { | |
2282 | uprobe_warn(current, "execute the probed insn, sending SIGILL."); | |
3cf5d076 | 2283 | force_sig(SIGILL); |
014940ba | 2284 | } |
0326f5a9 SD |
2285 | } |
2286 | ||
2287 | /* | |
1b08e907 ON |
2288 | * On breakpoint hit, breakpoint notifier sets the TIF_UPROBE flag and |
2289 | * allows the thread to return from interrupt. After that handle_swbp() | |
2290 | * sets utask->active_uprobe. | |
0326f5a9 | 2291 | * |
1b08e907 ON |
2292 | * On singlestep exception, singlestep notifier sets the TIF_UPROBE flag |
2293 | * and allows the thread to return from interrupt. | |
0326f5a9 SD |
2294 | * |
2295 | * While returning to userspace, thread notices the TIF_UPROBE flag and calls | |
2296 | * uprobe_notify_resume(). | |
2297 | */ | |
2298 | void uprobe_notify_resume(struct pt_regs *regs) | |
2299 | { | |
2300 | struct uprobe_task *utask; | |
2301 | ||
db023ea5 ON |
2302 | clear_thread_flag(TIF_UPROBE); |
2303 | ||
0326f5a9 | 2304 | utask = current->utask; |
1b08e907 | 2305 | if (utask && utask->active_uprobe) |
0326f5a9 | 2306 | handle_singlestep(utask, regs); |
1b08e907 ON |
2307 | else |
2308 | handle_swbp(regs); | |
0326f5a9 SD |
2309 | } |
2310 | ||
2311 | /* | |
2312 | * uprobe_pre_sstep_notifier gets called from interrupt context as part of | |
2313 | * notifier mechanism. Set TIF_UPROBE flag and indicate breakpoint hit. | |
2314 | */ | |
2315 | int uprobe_pre_sstep_notifier(struct pt_regs *regs) | |
2316 | { | |
0dfd0eb8 AA |
2317 | if (!current->mm) |
2318 | return 0; | |
2319 | ||
2320 | if (!test_bit(MMF_HAS_UPROBES, ¤t->mm->flags) && | |
2321 | (!current->utask || !current->utask->return_instances)) | |
0326f5a9 SD |
2322 | return 0; |
2323 | ||
0326f5a9 | 2324 | set_thread_flag(TIF_UPROBE); |
0326f5a9 SD |
2325 | return 1; |
2326 | } | |
2327 | ||
2328 | /* | |
2329 | * uprobe_post_sstep_notifier gets called in interrupt context as part of notifier | |
2330 | * mechanism. Set TIF_UPROBE flag and indicate completion of singlestep. | |
2331 | */ | |
2332 | int uprobe_post_sstep_notifier(struct pt_regs *regs) | |
2333 | { | |
2334 | struct uprobe_task *utask = current->utask; | |
2335 | ||
2336 | if (!current->mm || !utask || !utask->active_uprobe) | |
2337 | /* task is currently not uprobed */ | |
2338 | return 0; | |
2339 | ||
2340 | utask->state = UTASK_SSTEP_ACK; | |
2341 | set_thread_flag(TIF_UPROBE); | |
2342 | return 1; | |
2343 | } | |
2344 | ||
2345 | static struct notifier_block uprobe_exception_nb = { | |
2346 | .notifier_call = arch_uprobe_exception_notify, | |
2347 | .priority = INT_MAX-1, /* notified after kprobes, kgdb */ | |
2348 | }; | |
2349 | ||
aad42dd4 | 2350 | void __init uprobes_init(void) |
2b144498 SD |
2351 | { |
2352 | int i; | |
2353 | ||
66d06dff | 2354 | for (i = 0; i < UPROBES_HASH_SZ; i++) |
2b144498 | 2355 | mutex_init(&uprobes_mmap_mutex[i]); |
0326f5a9 | 2356 | |
aad42dd4 | 2357 | BUG_ON(register_die_notifier(&uprobe_exception_nb)); |
2b144498 | 2358 | } |