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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 */ | |
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> |
f385cb85 | 29 | #include <linux/khugepaged.h> |
7b2d81d4 | 30 | |
2b144498 SD |
31 | #include <linux/uprobes.h> |
32 | ||
d4b3b638 SD |
33 | #define UINSNS_PER_PAGE (PAGE_SIZE/UPROBE_XOL_SLOT_BYTES) |
34 | #define MAX_UPROBE_XOL_SLOTS UINSNS_PER_PAGE | |
35 | ||
2b144498 | 36 | static struct rb_root uprobes_tree = RB_ROOT; |
441f1eb7 ON |
37 | /* |
38 | * allows us to skip the uprobe_mmap if there are no uprobe events active | |
39 | * at this time. Probably a fine grained per inode count is better? | |
40 | */ | |
41 | #define no_uprobe_events() RB_EMPTY_ROOT(&uprobes_tree) | |
7b2d81d4 | 42 | |
2b144498 SD |
43 | static DEFINE_SPINLOCK(uprobes_treelock); /* serialize rbtree access */ |
44 | ||
45 | #define UPROBES_HASH_SZ 13 | |
2b144498 SD |
46 | /* serialize uprobe->pending_list */ |
47 | static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ]; | |
7b2d81d4 | 48 | #define uprobes_mmap_hash(v) (&uprobes_mmap_mutex[((unsigned long)(v)) % UPROBES_HASH_SZ]) |
2b144498 | 49 | |
2bf1acc2 | 50 | DEFINE_STATIC_PERCPU_RWSEM(dup_mmap_sem); |
32cdba1e | 51 | |
cb9a19fe | 52 | /* Have a copy of original instruction */ |
71434f2f | 53 | #define UPROBE_COPY_INSN 0 |
cb9a19fe | 54 | |
3ff54efd SD |
55 | struct uprobe { |
56 | struct rb_node rb_node; /* node in the rb tree */ | |
ce59b8e9 | 57 | refcount_t ref; |
e591c8d7 | 58 | struct rw_semaphore register_rwsem; |
3ff54efd SD |
59 | struct rw_semaphore consumer_rwsem; |
60 | struct list_head pending_list; | |
61 | struct uprobe_consumer *consumers; | |
62 | struct inode *inode; /* Also hold a ref to inode */ | |
63 | loff_t offset; | |
1cc33161 | 64 | loff_t ref_ctr_offset; |
71434f2f | 65 | unsigned long flags; |
ad439356 ON |
66 | |
67 | /* | |
68 | * The generic code assumes that it has two members of unknown type | |
69 | * owned by the arch-specific code: | |
70 | * | |
71 | * insn - copy_insn() saves the original instruction here for | |
72 | * arch_uprobe_analyze_insn(). | |
73 | * | |
74 | * ixol - potentially modified instruction to execute out of | |
75 | * line, copied to xol_area by xol_get_insn_slot(). | |
76 | */ | |
3ff54efd SD |
77 | struct arch_uprobe arch; |
78 | }; | |
79 | ||
1cc33161 RB |
80 | struct delayed_uprobe { |
81 | struct list_head list; | |
82 | struct uprobe *uprobe; | |
83 | struct mm_struct *mm; | |
84 | }; | |
85 | ||
86 | static DEFINE_MUTEX(delayed_uprobe_lock); | |
87 | static LIST_HEAD(delayed_uprobe_list); | |
88 | ||
c912dae6 | 89 | /* |
ad439356 ON |
90 | * Execute out of line area: anonymous executable mapping installed |
91 | * by the probed task to execute the copy of the original instruction | |
92 | * mangled by set_swbp(). | |
93 | * | |
c912dae6 ON |
94 | * On a breakpoint hit, thread contests for a slot. It frees the |
95 | * slot after singlestep. Currently a fixed number of slots are | |
96 | * allocated. | |
97 | */ | |
98 | struct xol_area { | |
704bde3c ON |
99 | wait_queue_head_t wq; /* if all slots are busy */ |
100 | atomic_t slot_count; /* number of in-use slots */ | |
101 | unsigned long *bitmap; /* 0 = free slot */ | |
c912dae6 | 102 | |
704bde3c ON |
103 | struct vm_special_mapping xol_mapping; |
104 | struct page *pages[2]; | |
c912dae6 ON |
105 | /* |
106 | * We keep the vma's vm_start rather than a pointer to the vma | |
107 | * itself. The probed process or a naughty kernel module could make | |
108 | * the vma go away, and we must handle that reasonably gracefully. | |
109 | */ | |
704bde3c | 110 | unsigned long vaddr; /* Page(s) of instruction slots */ |
c912dae6 ON |
111 | }; |
112 | ||
2b144498 SD |
113 | /* |
114 | * valid_vma: Verify if the specified vma is an executable vma | |
115 | * Relax restrictions while unregistering: vm_flags might have | |
116 | * changed after breakpoint was inserted. | |
117 | * - is_register: indicates if we are in register context. | |
118 | * - Return 1 if the specified virtual address is in an | |
119 | * executable vma. | |
120 | */ | |
121 | static bool valid_vma(struct vm_area_struct *vma, bool is_register) | |
122 | { | |
13f59c5e | 123 | vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_MAYSHARE; |
2b144498 | 124 | |
e40cfce6 ON |
125 | if (is_register) |
126 | flags |= VM_WRITE; | |
2b144498 | 127 | |
e40cfce6 | 128 | return vma->vm_file && (vma->vm_flags & flags) == VM_MAYEXEC; |
2b144498 SD |
129 | } |
130 | ||
57683f72 | 131 | static unsigned long offset_to_vaddr(struct vm_area_struct *vma, loff_t offset) |
2b144498 | 132 | { |
57683f72 | 133 | return vma->vm_start + offset - ((loff_t)vma->vm_pgoff << PAGE_SHIFT); |
2b144498 SD |
134 | } |
135 | ||
cb113b47 ON |
136 | static loff_t vaddr_to_offset(struct vm_area_struct *vma, unsigned long vaddr) |
137 | { | |
138 | return ((loff_t)vma->vm_pgoff << PAGE_SHIFT) + (vaddr - vma->vm_start); | |
139 | } | |
140 | ||
2b144498 SD |
141 | /** |
142 | * __replace_page - replace page in vma by new page. | |
143 | * based on replace_page in mm/ksm.c | |
144 | * | |
145 | * @vma: vma that holds the pte pointing to page | |
c517ee74 | 146 | * @addr: address the old @page is mapped at |
fb4fb04f SL |
147 | * @old_page: the page we are replacing by new_page |
148 | * @new_page: the modified page we replace page by | |
2b144498 | 149 | * |
fb4fb04f SL |
150 | * If @new_page is NULL, only unmap @old_page. |
151 | * | |
152 | * Returns 0 on success, negative error code otherwise. | |
2b144498 | 153 | */ |
c517ee74 | 154 | static int __replace_page(struct vm_area_struct *vma, unsigned long addr, |
bdfaa2ee | 155 | struct page *old_page, struct page *new_page) |
2b144498 | 156 | { |
5fcd079a | 157 | struct folio *old_folio = page_folio(old_page); |
82e66bf7 | 158 | struct folio *new_folio; |
2b144498 | 159 | struct mm_struct *mm = vma->vm_mm; |
5fcd079a | 160 | DEFINE_FOLIO_VMA_WALK(pvmw, old_folio, vma, addr, 0); |
9f92448c | 161 | int err; |
ac46d4f3 | 162 | struct mmu_notifier_range range; |
00501b53 | 163 | |
7269f999 | 164 | mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm, addr, |
6f4f13e8 | 165 | addr + PAGE_SIZE); |
ac46d4f3 | 166 | |
fb4fb04f | 167 | if (new_page) { |
82e66bf7 MWO |
168 | new_folio = page_folio(new_page); |
169 | err = mem_cgroup_charge(new_folio, vma->vm_mm, GFP_KERNEL); | |
fb4fb04f SL |
170 | if (err) |
171 | return err; | |
172 | } | |
2b144498 | 173 | |
5fcd079a MWO |
174 | /* For folio_free_swap() below */ |
175 | folio_lock(old_folio); | |
9f92448c | 176 | |
ac46d4f3 | 177 | mmu_notifier_invalidate_range_start(&range); |
9f92448c | 178 | err = -EAGAIN; |
9d82c694 | 179 | if (!page_vma_mapped_walk(&pvmw)) |
9f92448c | 180 | goto unlock; |
14fa2daa | 181 | VM_BUG_ON_PAGE(addr != pvmw.address, old_page); |
2b144498 | 182 | |
fb4fb04f | 183 | if (new_page) { |
82e66bf7 | 184 | folio_get(new_folio); |
40f2bbf7 | 185 | page_add_new_anon_rmap(new_page, vma, addr); |
82e66bf7 | 186 | folio_add_lru_vma(new_folio, vma); |
fb4fb04f SL |
187 | } else |
188 | /* no new page, just dec_mm_counter for old_page */ | |
189 | dec_mm_counter(mm, MM_ANONPAGES); | |
2b144498 | 190 | |
5fcd079a | 191 | if (!folio_test_anon(old_folio)) { |
bdfaa2ee | 192 | dec_mm_counter(mm, mm_counter_file(old_page)); |
7396fa81 SD |
193 | inc_mm_counter(mm, MM_ANONPAGES); |
194 | } | |
195 | ||
14fa2daa KS |
196 | flush_cache_page(vma, addr, pte_pfn(*pvmw.pte)); |
197 | ptep_clear_flush_notify(vma, addr, pvmw.pte); | |
fb4fb04f SL |
198 | if (new_page) |
199 | set_pte_at_notify(mm, addr, pvmw.pte, | |
200 | mk_pte(new_page, vma->vm_page_prot)); | |
2b144498 | 201 | |
cea86fe2 | 202 | page_remove_rmap(old_page, vma, false); |
5fcd079a MWO |
203 | if (!folio_mapped(old_folio)) |
204 | folio_free_swap(old_folio); | |
14fa2daa | 205 | page_vma_mapped_walk_done(&pvmw); |
5fcd079a | 206 | folio_put(old_folio); |
194f8dcb | 207 | |
9f92448c ON |
208 | err = 0; |
209 | unlock: | |
ac46d4f3 | 210 | mmu_notifier_invalidate_range_end(&range); |
5fcd079a | 211 | folio_unlock(old_folio); |
9f92448c | 212 | return err; |
2b144498 SD |
213 | } |
214 | ||
215 | /** | |
5cb4ac3a | 216 | * is_swbp_insn - check if instruction is breakpoint instruction. |
2b144498 | 217 | * @insn: instruction to be checked. |
5cb4ac3a | 218 | * Default implementation of is_swbp_insn |
2b144498 SD |
219 | * Returns true if @insn is a breakpoint instruction. |
220 | */ | |
5cb4ac3a | 221 | bool __weak is_swbp_insn(uprobe_opcode_t *insn) |
2b144498 | 222 | { |
5cb4ac3a | 223 | return *insn == UPROBE_SWBP_INSN; |
2b144498 SD |
224 | } |
225 | ||
0908ad6e AM |
226 | /** |
227 | * is_trap_insn - check if instruction is breakpoint instruction. | |
228 | * @insn: instruction to be checked. | |
229 | * Default implementation of is_trap_insn | |
230 | * Returns true if @insn is a breakpoint instruction. | |
231 | * | |
232 | * This function is needed for the case where an architecture has multiple | |
233 | * trap instructions (like powerpc). | |
234 | */ | |
235 | bool __weak is_trap_insn(uprobe_opcode_t *insn) | |
236 | { | |
237 | return is_swbp_insn(insn); | |
238 | } | |
239 | ||
ab0d805c | 240 | static void copy_from_page(struct page *page, unsigned long vaddr, void *dst, int len) |
cceb55aa ON |
241 | { |
242 | void *kaddr = kmap_atomic(page); | |
ab0d805c | 243 | memcpy(dst, kaddr + (vaddr & ~PAGE_MASK), len); |
cceb55aa ON |
244 | kunmap_atomic(kaddr); |
245 | } | |
246 | ||
5669ccee ON |
247 | static void copy_to_page(struct page *page, unsigned long vaddr, const void *src, int len) |
248 | { | |
249 | void *kaddr = kmap_atomic(page); | |
250 | memcpy(kaddr + (vaddr & ~PAGE_MASK), src, len); | |
251 | kunmap_atomic(kaddr); | |
252 | } | |
253 | ||
ed6f6a50 ON |
254 | static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *new_opcode) |
255 | { | |
256 | uprobe_opcode_t old_opcode; | |
257 | bool is_swbp; | |
258 | ||
0908ad6e AM |
259 | /* |
260 | * Note: We only check if the old_opcode is UPROBE_SWBP_INSN here. | |
261 | * We do not check if it is any other 'trap variant' which could | |
262 | * be conditional trap instruction such as the one powerpc supports. | |
263 | * | |
264 | * The logic is that we do not care if the underlying instruction | |
265 | * is a trap variant; uprobes always wins over any other (gdb) | |
266 | * breakpoint. | |
267 | */ | |
ab0d805c | 268 | copy_from_page(page, vaddr, &old_opcode, UPROBE_SWBP_INSN_SIZE); |
ed6f6a50 ON |
269 | is_swbp = is_swbp_insn(&old_opcode); |
270 | ||
271 | if (is_swbp_insn(new_opcode)) { | |
272 | if (is_swbp) /* register: already installed? */ | |
273 | return 0; | |
274 | } else { | |
275 | if (!is_swbp) /* unregister: was it changed by us? */ | |
076a365b | 276 | return 0; |
ed6f6a50 ON |
277 | } |
278 | ||
279 | return 1; | |
280 | } | |
281 | ||
1cc33161 RB |
282 | static struct delayed_uprobe * |
283 | delayed_uprobe_check(struct uprobe *uprobe, struct mm_struct *mm) | |
284 | { | |
285 | struct delayed_uprobe *du; | |
286 | ||
287 | list_for_each_entry(du, &delayed_uprobe_list, list) | |
288 | if (du->uprobe == uprobe && du->mm == mm) | |
289 | return du; | |
290 | return NULL; | |
291 | } | |
292 | ||
293 | static int delayed_uprobe_add(struct uprobe *uprobe, struct mm_struct *mm) | |
294 | { | |
295 | struct delayed_uprobe *du; | |
296 | ||
297 | if (delayed_uprobe_check(uprobe, mm)) | |
298 | return 0; | |
299 | ||
300 | du = kzalloc(sizeof(*du), GFP_KERNEL); | |
301 | if (!du) | |
302 | return -ENOMEM; | |
303 | ||
304 | du->uprobe = uprobe; | |
305 | du->mm = mm; | |
306 | list_add(&du->list, &delayed_uprobe_list); | |
307 | return 0; | |
308 | } | |
309 | ||
310 | static void delayed_uprobe_delete(struct delayed_uprobe *du) | |
311 | { | |
312 | if (WARN_ON(!du)) | |
313 | return; | |
314 | list_del(&du->list); | |
315 | kfree(du); | |
316 | } | |
317 | ||
318 | static void delayed_uprobe_remove(struct uprobe *uprobe, struct mm_struct *mm) | |
319 | { | |
320 | struct list_head *pos, *q; | |
321 | struct delayed_uprobe *du; | |
322 | ||
323 | if (!uprobe && !mm) | |
324 | return; | |
325 | ||
326 | list_for_each_safe(pos, q, &delayed_uprobe_list) { | |
327 | du = list_entry(pos, struct delayed_uprobe, list); | |
328 | ||
329 | if (uprobe && du->uprobe != uprobe) | |
330 | continue; | |
331 | if (mm && du->mm != mm) | |
332 | continue; | |
333 | ||
334 | delayed_uprobe_delete(du); | |
335 | } | |
336 | } | |
337 | ||
338 | static bool valid_ref_ctr_vma(struct uprobe *uprobe, | |
339 | struct vm_area_struct *vma) | |
340 | { | |
341 | unsigned long vaddr = offset_to_vaddr(vma, uprobe->ref_ctr_offset); | |
342 | ||
343 | return uprobe->ref_ctr_offset && | |
344 | vma->vm_file && | |
345 | file_inode(vma->vm_file) == uprobe->inode && | |
346 | (vma->vm_flags & (VM_WRITE|VM_SHARED)) == VM_WRITE && | |
347 | vma->vm_start <= vaddr && | |
348 | vma->vm_end > vaddr; | |
349 | } | |
350 | ||
351 | static struct vm_area_struct * | |
352 | find_ref_ctr_vma(struct uprobe *uprobe, struct mm_struct *mm) | |
353 | { | |
fcb72a58 | 354 | VMA_ITERATOR(vmi, mm, 0); |
1cc33161 RB |
355 | struct vm_area_struct *tmp; |
356 | ||
fcb72a58 | 357 | for_each_vma(vmi, tmp) |
1cc33161 RB |
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 | ||
64019a2e | 376 | ret = get_user_pages_remote(mm, vaddr, 1, |
1cc33161 RB |
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. |
9ce4d216 | 453 | * @auprobe: arch specific probepoint information. |
2b144498 | 454 | * @mm: the probed process address space. |
2b144498 SD |
455 | * @vaddr: the virtual address to store the opcode. |
456 | * @opcode: opcode to be written at @vaddr. | |
457 | * | |
c1e8d7c6 | 458 | * Called with mm->mmap_lock held for write. |
2b144498 SD |
459 | * Return 0 (success) or a negative errno. |
460 | */ | |
6d43743e RB |
461 | int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, |
462 | unsigned long vaddr, uprobe_opcode_t opcode) | |
2b144498 | 463 | { |
1cc33161 | 464 | struct uprobe *uprobe; |
2b144498 | 465 | struct page *old_page, *new_page; |
2b144498 | 466 | struct vm_area_struct *vma; |
1cc33161 | 467 | int ret, is_register, ref_ctr_updated = 0; |
f385cb85 | 468 | bool orig_page_huge = false; |
aa5de305 | 469 | unsigned int gup_flags = FOLL_FORCE; |
1cc33161 RB |
470 | |
471 | is_register = is_swbp_insn(&opcode); | |
472 | uprobe = container_of(auprobe, struct uprobe, arch); | |
f403072c | 473 | |
5323ce71 | 474 | retry: |
aa5de305 SL |
475 | if (is_register) |
476 | gup_flags |= FOLL_SPLIT_PMD; | |
2b144498 | 477 | /* Read the page with vaddr into memory */ |
64019a2e | 478 | ret = get_user_pages_remote(mm, vaddr, 1, gup_flags, |
aa5de305 | 479 | &old_page, &vma, NULL); |
2b144498 SD |
480 | if (ret <= 0) |
481 | return ret; | |
7b2d81d4 | 482 | |
ed6f6a50 ON |
483 | ret = verify_opcode(old_page, vaddr, &opcode); |
484 | if (ret <= 0) | |
485 | goto put_old; | |
486 | ||
aa5de305 SL |
487 | if (WARN(!is_register && PageCompound(old_page), |
488 | "uprobe unregister should never work on compound page\n")) { | |
489 | ret = -EINVAL; | |
490 | goto put_old; | |
491 | } | |
492 | ||
1cc33161 RB |
493 | /* We are going to replace instruction, update ref_ctr. */ |
494 | if (!ref_ctr_updated && uprobe->ref_ctr_offset) { | |
495 | ret = update_ref_ctr(uprobe, mm, is_register ? 1 : -1); | |
496 | if (ret) | |
497 | goto put_old; | |
498 | ||
499 | ref_ctr_updated = 1; | |
500 | } | |
501 | ||
fb4fb04f SL |
502 | ret = 0; |
503 | if (!is_register && !PageAnon(old_page)) | |
504 | goto put_old; | |
505 | ||
29dedee0 ON |
506 | ret = anon_vma_prepare(vma); |
507 | if (ret) | |
508 | goto put_old; | |
509 | ||
2b144498 SD |
510 | ret = -ENOMEM; |
511 | new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr); | |
512 | if (!new_page) | |
9f92448c | 513 | goto put_old; |
2b144498 | 514 | |
29dedee0 | 515 | __SetPageUptodate(new_page); |
3f47107c ON |
516 | copy_highpage(new_page, old_page); |
517 | copy_to_page(new_page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE); | |
2b144498 | 518 | |
fb4fb04f SL |
519 | if (!is_register) { |
520 | struct page *orig_page; | |
521 | pgoff_t index; | |
522 | ||
523 | VM_BUG_ON_PAGE(!PageAnon(old_page), old_page); | |
524 | ||
525 | index = vaddr_to_offset(vma, vaddr & PAGE_MASK) >> PAGE_SHIFT; | |
526 | orig_page = find_get_page(vma->vm_file->f_inode->i_mapping, | |
527 | index); | |
528 | ||
529 | if (orig_page) { | |
530 | if (PageUptodate(orig_page) && | |
531 | pages_identical(new_page, orig_page)) { | |
532 | /* let go new_page */ | |
533 | put_page(new_page); | |
534 | new_page = NULL; | |
f385cb85 SL |
535 | |
536 | if (PageCompound(orig_page)) | |
537 | orig_page_huge = true; | |
fb4fb04f SL |
538 | } |
539 | put_page(orig_page); | |
540 | } | |
541 | } | |
542 | ||
c517ee74 | 543 | ret = __replace_page(vma, vaddr, old_page, new_page); |
fb4fb04f SL |
544 | if (new_page) |
545 | put_page(new_page); | |
9f92448c | 546 | put_old: |
7b2d81d4 IM |
547 | put_page(old_page); |
548 | ||
5323ce71 ON |
549 | if (unlikely(ret == -EAGAIN)) |
550 | goto retry; | |
1cc33161 RB |
551 | |
552 | /* Revert back reference counter if instruction update failed. */ | |
553 | if (ret && is_register && ref_ctr_updated) | |
554 | update_ref_ctr(uprobe, mm, -1); | |
555 | ||
f385cb85 SL |
556 | /* try collapse pmd for compound page */ |
557 | if (!ret && orig_page_huge) | |
34488399 | 558 | collapse_pte_mapped_thp(mm, vaddr, false); |
f385cb85 | 559 | |
2b144498 SD |
560 | return ret; |
561 | } | |
562 | ||
2b144498 | 563 | /** |
5cb4ac3a | 564 | * set_swbp - store breakpoint at a given address. |
e3343e6a | 565 | * @auprobe: arch specific probepoint information. |
2b144498 | 566 | * @mm: the probed process address space. |
2b144498 SD |
567 | * @vaddr: the virtual address to insert the opcode. |
568 | * | |
569 | * For mm @mm, store the breakpoint instruction at @vaddr. | |
570 | * Return 0 (success) or a negative errno. | |
571 | */ | |
5cb4ac3a | 572 | int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) |
2b144498 | 573 | { |
6d43743e | 574 | return uprobe_write_opcode(auprobe, mm, vaddr, UPROBE_SWBP_INSN); |
2b144498 SD |
575 | } |
576 | ||
577 | /** | |
578 | * set_orig_insn - Restore the original instruction. | |
579 | * @mm: the probed process address space. | |
e3343e6a | 580 | * @auprobe: arch specific probepoint information. |
2b144498 | 581 | * @vaddr: the virtual address to insert the opcode. |
2b144498 SD |
582 | * |
583 | * For mm @mm, restore the original opcode (opcode) at @vaddr. | |
584 | * Return 0 (success) or a negative errno. | |
585 | */ | |
7b2d81d4 | 586 | int __weak |
ded86e7c | 587 | set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) |
2b144498 | 588 | { |
6d43743e RB |
589 | return uprobe_write_opcode(auprobe, mm, vaddr, |
590 | *(uprobe_opcode_t *)&auprobe->insn); | |
2b144498 SD |
591 | } |
592 | ||
f231722a ON |
593 | static struct uprobe *get_uprobe(struct uprobe *uprobe) |
594 | { | |
ce59b8e9 | 595 | refcount_inc(&uprobe->ref); |
f231722a ON |
596 | return uprobe; |
597 | } | |
598 | ||
599 | static void put_uprobe(struct uprobe *uprobe) | |
600 | { | |
ce59b8e9 | 601 | if (refcount_dec_and_test(&uprobe->ref)) { |
1cc33161 RB |
602 | /* |
603 | * If application munmap(exec_vma) before uprobe_unregister() | |
604 | * gets called, we don't get a chance to remove uprobe from | |
605 | * delayed_uprobe_list from remove_breakpoint(). Do it here. | |
606 | */ | |
1aed58e6 | 607 | mutex_lock(&delayed_uprobe_lock); |
1cc33161 | 608 | delayed_uprobe_remove(uprobe, NULL); |
1aed58e6 | 609 | mutex_unlock(&delayed_uprobe_lock); |
f231722a | 610 | kfree(uprobe); |
1cc33161 | 611 | } |
f231722a ON |
612 | } |
613 | ||
a905e84e PZ |
614 | static __always_inline |
615 | int uprobe_cmp(const struct inode *l_inode, const loff_t l_offset, | |
616 | const struct uprobe *r) | |
2b144498 | 617 | { |
a905e84e | 618 | if (l_inode < r->inode) |
2b144498 | 619 | return -1; |
7b2d81d4 | 620 | |
a905e84e | 621 | if (l_inode > r->inode) |
2b144498 | 622 | return 1; |
2b144498 | 623 | |
a905e84e | 624 | if (l_offset < r->offset) |
7b2d81d4 IM |
625 | return -1; |
626 | ||
a905e84e | 627 | if (l_offset > r->offset) |
7b2d81d4 | 628 | return 1; |
2b144498 SD |
629 | |
630 | return 0; | |
631 | } | |
632 | ||
a905e84e PZ |
633 | #define __node_2_uprobe(node) \ |
634 | rb_entry((node), struct uprobe, rb_node) | |
635 | ||
636 | struct __uprobe_key { | |
637 | struct inode *inode; | |
638 | loff_t offset; | |
639 | }; | |
640 | ||
641 | static inline int __uprobe_cmp_key(const void *key, const struct rb_node *b) | |
642 | { | |
643 | const struct __uprobe_key *a = key; | |
644 | return uprobe_cmp(a->inode, a->offset, __node_2_uprobe(b)); | |
645 | } | |
646 | ||
647 | static inline int __uprobe_cmp(struct rb_node *a, const struct rb_node *b) | |
648 | { | |
649 | struct uprobe *u = __node_2_uprobe(a); | |
650 | return uprobe_cmp(u->inode, u->offset, __node_2_uprobe(b)); | |
651 | } | |
652 | ||
2b144498 SD |
653 | static struct uprobe *__find_uprobe(struct inode *inode, loff_t offset) |
654 | { | |
a905e84e PZ |
655 | struct __uprobe_key key = { |
656 | .inode = inode, | |
657 | .offset = offset, | |
658 | }; | |
659 | struct rb_node *node = rb_find(&key, &uprobes_tree, __uprobe_cmp_key); | |
660 | ||
661 | if (node) | |
b0d6d478 | 662 | return get_uprobe(__node_2_uprobe(node)); |
a905e84e | 663 | |
2b144498 SD |
664 | return NULL; |
665 | } | |
666 | ||
667 | /* | |
668 | * Find a uprobe corresponding to a given inode:offset | |
669 | * Acquires uprobes_treelock | |
670 | */ | |
671 | static struct uprobe *find_uprobe(struct inode *inode, loff_t offset) | |
672 | { | |
673 | struct uprobe *uprobe; | |
2b144498 | 674 | |
6f47caa0 | 675 | spin_lock(&uprobes_treelock); |
2b144498 | 676 | uprobe = __find_uprobe(inode, offset); |
6f47caa0 | 677 | spin_unlock(&uprobes_treelock); |
7b2d81d4 | 678 | |
2b144498 SD |
679 | return uprobe; |
680 | } | |
681 | ||
682 | static struct uprobe *__insert_uprobe(struct uprobe *uprobe) | |
683 | { | |
a905e84e | 684 | struct rb_node *node; |
2b144498 | 685 | |
a905e84e PZ |
686 | node = rb_find_add(&uprobe->rb_node, &uprobes_tree, __uprobe_cmp); |
687 | if (node) | |
688 | return get_uprobe(__node_2_uprobe(node)); | |
2b144498 | 689 | |
2b144498 | 690 | /* get access + creation ref */ |
ce59b8e9 | 691 | refcount_set(&uprobe->ref, 2); |
a905e84e | 692 | return NULL; |
2b144498 SD |
693 | } |
694 | ||
695 | /* | |
7b2d81d4 | 696 | * Acquire uprobes_treelock. |
2b144498 SD |
697 | * Matching uprobe already exists in rbtree; |
698 | * increment (access refcount) and return the matching uprobe. | |
699 | * | |
700 | * No matching uprobe; insert the uprobe in rb_tree; | |
701 | * get a double refcount (access + creation) and return NULL. | |
702 | */ | |
703 | static struct uprobe *insert_uprobe(struct uprobe *uprobe) | |
704 | { | |
2b144498 SD |
705 | struct uprobe *u; |
706 | ||
6f47caa0 | 707 | spin_lock(&uprobes_treelock); |
2b144498 | 708 | u = __insert_uprobe(uprobe); |
6f47caa0 | 709 | spin_unlock(&uprobes_treelock); |
7b2d81d4 | 710 | |
2b144498 SD |
711 | return u; |
712 | } | |
713 | ||
22bad382 RB |
714 | static void |
715 | ref_ctr_mismatch_warn(struct uprobe *cur_uprobe, struct uprobe *uprobe) | |
716 | { | |
717 | pr_warn("ref_ctr_offset mismatch. inode: 0x%lx offset: 0x%llx " | |
718 | "ref_ctr_offset(old): 0x%llx ref_ctr_offset(new): 0x%llx\n", | |
719 | uprobe->inode->i_ino, (unsigned long long) uprobe->offset, | |
720 | (unsigned long long) cur_uprobe->ref_ctr_offset, | |
721 | (unsigned long long) uprobe->ref_ctr_offset); | |
722 | } | |
723 | ||
1cc33161 RB |
724 | static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset, |
725 | loff_t ref_ctr_offset) | |
2b144498 SD |
726 | { |
727 | struct uprobe *uprobe, *cur_uprobe; | |
728 | ||
729 | uprobe = kzalloc(sizeof(struct uprobe), GFP_KERNEL); | |
730 | if (!uprobe) | |
731 | return NULL; | |
732 | ||
61f94203 | 733 | uprobe->inode = inode; |
2b144498 | 734 | uprobe->offset = offset; |
1cc33161 | 735 | uprobe->ref_ctr_offset = ref_ctr_offset; |
e591c8d7 | 736 | init_rwsem(&uprobe->register_rwsem); |
2b144498 | 737 | init_rwsem(&uprobe->consumer_rwsem); |
2b144498 SD |
738 | |
739 | /* add to uprobes_tree, sorted on inode:offset */ | |
740 | cur_uprobe = insert_uprobe(uprobe); | |
2b144498 SD |
741 | /* a uprobe exists for this inode:offset combination */ |
742 | if (cur_uprobe) { | |
22bad382 RB |
743 | if (cur_uprobe->ref_ctr_offset != uprobe->ref_ctr_offset) { |
744 | ref_ctr_mismatch_warn(cur_uprobe, uprobe); | |
745 | put_uprobe(cur_uprobe); | |
746 | kfree(uprobe); | |
747 | return ERR_PTR(-EINVAL); | |
748 | } | |
2b144498 SD |
749 | kfree(uprobe); |
750 | uprobe = cur_uprobe; | |
7b2d81d4 IM |
751 | } |
752 | ||
2b144498 SD |
753 | return uprobe; |
754 | } | |
755 | ||
9a98e03c | 756 | static void consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc) |
2b144498 SD |
757 | { |
758 | down_write(&uprobe->consumer_rwsem); | |
e3343e6a SD |
759 | uc->next = uprobe->consumers; |
760 | uprobe->consumers = uc; | |
2b144498 | 761 | up_write(&uprobe->consumer_rwsem); |
2b144498 SD |
762 | } |
763 | ||
764 | /* | |
e3343e6a SD |
765 | * For uprobe @uprobe, delete the consumer @uc. |
766 | * Return true if the @uc is deleted successfully | |
2b144498 SD |
767 | * or return false. |
768 | */ | |
e3343e6a | 769 | static bool consumer_del(struct uprobe *uprobe, struct uprobe_consumer *uc) |
2b144498 SD |
770 | { |
771 | struct uprobe_consumer **con; | |
772 | bool ret = false; | |
773 | ||
774 | down_write(&uprobe->consumer_rwsem); | |
775 | for (con = &uprobe->consumers; *con; con = &(*con)->next) { | |
e3343e6a SD |
776 | if (*con == uc) { |
777 | *con = uc->next; | |
2b144498 SD |
778 | ret = true; |
779 | break; | |
780 | } | |
781 | } | |
782 | up_write(&uprobe->consumer_rwsem); | |
7b2d81d4 | 783 | |
2b144498 SD |
784 | return ret; |
785 | } | |
786 | ||
2ded0980 ON |
787 | static int __copy_insn(struct address_space *mapping, struct file *filp, |
788 | void *insn, int nbytes, loff_t offset) | |
2b144498 | 789 | { |
2b144498 | 790 | struct page *page; |
2b144498 | 791 | /* |
40814f68 | 792 | * Ensure that the page that has the original instruction is populated |
7e0a1265 | 793 | * and in page-cache. If ->read_folio == NULL it must be shmem_mapping(), |
40814f68 | 794 | * see uprobe_register(). |
2b144498 | 795 | */ |
7e0a1265 | 796 | if (mapping->a_ops->read_folio) |
09cbfeaf | 797 | page = read_mapping_page(mapping, offset >> PAGE_SHIFT, filp); |
40814f68 | 798 | else |
09cbfeaf | 799 | page = shmem_read_mapping_page(mapping, offset >> PAGE_SHIFT); |
2b144498 SD |
800 | if (IS_ERR(page)) |
801 | return PTR_ERR(page); | |
802 | ||
2edb7b55 | 803 | copy_from_page(page, offset, insn, nbytes); |
09cbfeaf | 804 | put_page(page); |
7b2d81d4 | 805 | |
2b144498 SD |
806 | return 0; |
807 | } | |
808 | ||
d436615e | 809 | static int copy_insn(struct uprobe *uprobe, struct file *filp) |
2b144498 | 810 | { |
2ded0980 ON |
811 | struct address_space *mapping = uprobe->inode->i_mapping; |
812 | loff_t offs = uprobe->offset; | |
803200e2 ON |
813 | void *insn = &uprobe->arch.insn; |
814 | int size = sizeof(uprobe->arch.insn); | |
2ded0980 ON |
815 | int len, err = -EIO; |
816 | ||
817 | /* Copy only available bytes, -EIO if nothing was read */ | |
818 | do { | |
819 | if (offs >= i_size_read(uprobe->inode)) | |
820 | break; | |
821 | ||
822 | len = min_t(int, size, PAGE_SIZE - (offs & ~PAGE_MASK)); | |
823 | err = __copy_insn(mapping, filp, insn, len, offs); | |
fc36f595 | 824 | if (err) |
2ded0980 ON |
825 | break; |
826 | ||
827 | insn += len; | |
828 | offs += len; | |
829 | size -= len; | |
830 | } while (size); | |
831 | ||
832 | return err; | |
2b144498 SD |
833 | } |
834 | ||
cb9a19fe ON |
835 | static int prepare_uprobe(struct uprobe *uprobe, struct file *file, |
836 | struct mm_struct *mm, unsigned long vaddr) | |
837 | { | |
838 | int ret = 0; | |
839 | ||
71434f2f | 840 | if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) |
cb9a19fe ON |
841 | return ret; |
842 | ||
d4d3ccc6 ON |
843 | /* TODO: move this into _register, until then we abuse this sem. */ |
844 | down_write(&uprobe->consumer_rwsem); | |
71434f2f | 845 | if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) |
4710f05f ON |
846 | goto out; |
847 | ||
cb9a19fe ON |
848 | ret = copy_insn(uprobe, file); |
849 | if (ret) | |
850 | goto out; | |
851 | ||
852 | ret = -ENOTSUPP; | |
803200e2 | 853 | if (is_trap_insn((uprobe_opcode_t *)&uprobe->arch.insn)) |
cb9a19fe ON |
854 | goto out; |
855 | ||
856 | ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, vaddr); | |
857 | if (ret) | |
858 | goto out; | |
859 | ||
09d3f015 | 860 | smp_wmb(); /* pairs with the smp_rmb() in handle_swbp() */ |
71434f2f | 861 | set_bit(UPROBE_COPY_INSN, &uprobe->flags); |
cb9a19fe ON |
862 | |
863 | out: | |
d4d3ccc6 | 864 | up_write(&uprobe->consumer_rwsem); |
4710f05f | 865 | |
cb9a19fe ON |
866 | return ret; |
867 | } | |
868 | ||
8a7f2fa0 ON |
869 | static inline bool consumer_filter(struct uprobe_consumer *uc, |
870 | enum uprobe_filter_ctx ctx, struct mm_struct *mm) | |
806a98bd | 871 | { |
8a7f2fa0 | 872 | return !uc->filter || uc->filter(uc, ctx, mm); |
806a98bd ON |
873 | } |
874 | ||
8a7f2fa0 ON |
875 | static bool filter_chain(struct uprobe *uprobe, |
876 | enum uprobe_filter_ctx ctx, struct mm_struct *mm) | |
63633cbf | 877 | { |
1ff6fee5 ON |
878 | struct uprobe_consumer *uc; |
879 | bool ret = false; | |
880 | ||
881 | down_read(&uprobe->consumer_rwsem); | |
882 | for (uc = uprobe->consumers; uc; uc = uc->next) { | |
8a7f2fa0 | 883 | ret = consumer_filter(uc, ctx, mm); |
1ff6fee5 ON |
884 | if (ret) |
885 | break; | |
886 | } | |
887 | up_read(&uprobe->consumer_rwsem); | |
888 | ||
889 | return ret; | |
63633cbf ON |
890 | } |
891 | ||
e3343e6a SD |
892 | static int |
893 | install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, | |
816c03fb | 894 | struct vm_area_struct *vma, unsigned long vaddr) |
2b144498 | 895 | { |
f8ac4ec9 | 896 | bool first_uprobe; |
2b144498 SD |
897 | int ret; |
898 | ||
cb9a19fe ON |
899 | ret = prepare_uprobe(uprobe, vma->vm_file, mm, vaddr); |
900 | if (ret) | |
901 | return ret; | |
682968e0 | 902 | |
f8ac4ec9 ON |
903 | /* |
904 | * set MMF_HAS_UPROBES in advance for uprobe_pre_sstep_notifier(), | |
905 | * the task can hit this breakpoint right after __replace_page(). | |
906 | */ | |
907 | first_uprobe = !test_bit(MMF_HAS_UPROBES, &mm->flags); | |
908 | if (first_uprobe) | |
909 | set_bit(MMF_HAS_UPROBES, &mm->flags); | |
910 | ||
816c03fb | 911 | ret = set_swbp(&uprobe->arch, mm, vaddr); |
9f68f672 ON |
912 | if (!ret) |
913 | clear_bit(MMF_RECALC_UPROBES, &mm->flags); | |
914 | else if (first_uprobe) | |
f8ac4ec9 | 915 | clear_bit(MMF_HAS_UPROBES, &mm->flags); |
2b144498 SD |
916 | |
917 | return ret; | |
918 | } | |
919 | ||
076a365b | 920 | static int |
816c03fb | 921 | remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr) |
2b144498 | 922 | { |
9f68f672 | 923 | set_bit(MMF_RECALC_UPROBES, &mm->flags); |
076a365b | 924 | return set_orig_insn(&uprobe->arch, mm, vaddr); |
2b144498 SD |
925 | } |
926 | ||
06b7bcd8 ON |
927 | static inline bool uprobe_is_active(struct uprobe *uprobe) |
928 | { | |
929 | return !RB_EMPTY_NODE(&uprobe->rb_node); | |
930 | } | |
0326f5a9 | 931 | /* |
778b032d ON |
932 | * There could be threads that have already hit the breakpoint. They |
933 | * will recheck the current insn and restart if find_uprobe() fails. | |
934 | * See find_active_uprobe(). | |
0326f5a9 | 935 | */ |
2b144498 SD |
936 | static void delete_uprobe(struct uprobe *uprobe) |
937 | { | |
06b7bcd8 ON |
938 | if (WARN_ON(!uprobe_is_active(uprobe))) |
939 | return; | |
940 | ||
6f47caa0 | 941 | spin_lock(&uprobes_treelock); |
2b144498 | 942 | rb_erase(&uprobe->rb_node, &uprobes_tree); |
6f47caa0 | 943 | spin_unlock(&uprobes_treelock); |
06b7bcd8 | 944 | RB_CLEAR_NODE(&uprobe->rb_node); /* for uprobe_is_active() */ |
2b144498 | 945 | put_uprobe(uprobe); |
2b144498 SD |
946 | } |
947 | ||
26872090 ON |
948 | struct map_info { |
949 | struct map_info *next; | |
950 | struct mm_struct *mm; | |
816c03fb | 951 | unsigned long vaddr; |
26872090 ON |
952 | }; |
953 | ||
954 | static inline struct map_info *free_map_info(struct map_info *info) | |
2b144498 | 955 | { |
26872090 ON |
956 | struct map_info *next = info->next; |
957 | kfree(info); | |
958 | return next; | |
959 | } | |
960 | ||
961 | static struct map_info * | |
962 | build_map_info(struct address_space *mapping, loff_t offset, bool is_register) | |
963 | { | |
964 | unsigned long pgoff = offset >> PAGE_SHIFT; | |
2b144498 | 965 | struct vm_area_struct *vma; |
26872090 ON |
966 | struct map_info *curr = NULL; |
967 | struct map_info *prev = NULL; | |
968 | struct map_info *info; | |
969 | int more = 0; | |
2b144498 | 970 | |
26872090 | 971 | again: |
4a23717a | 972 | i_mmap_lock_read(mapping); |
6b2dbba8 | 973 | vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { |
2b144498 SD |
974 | if (!valid_vma(vma, is_register)) |
975 | continue; | |
976 | ||
7a5bfb66 ON |
977 | if (!prev && !more) { |
978 | /* | |
c8c06efa | 979 | * Needs GFP_NOWAIT to avoid i_mmap_rwsem recursion through |
7a5bfb66 ON |
980 | * reclaim. This is optimistic, no harm done if it fails. |
981 | */ | |
982 | prev = kmalloc(sizeof(struct map_info), | |
983 | GFP_NOWAIT | __GFP_NOMEMALLOC | __GFP_NOWARN); | |
984 | if (prev) | |
985 | prev->next = NULL; | |
986 | } | |
26872090 ON |
987 | if (!prev) { |
988 | more++; | |
989 | continue; | |
2b144498 | 990 | } |
2b144498 | 991 | |
388f7934 | 992 | if (!mmget_not_zero(vma->vm_mm)) |
26872090 | 993 | continue; |
7b2d81d4 | 994 | |
26872090 ON |
995 | info = prev; |
996 | prev = prev->next; | |
997 | info->next = curr; | |
998 | curr = info; | |
2b144498 | 999 | |
26872090 | 1000 | info->mm = vma->vm_mm; |
57683f72 | 1001 | info->vaddr = offset_to_vaddr(vma, offset); |
26872090 | 1002 | } |
4a23717a | 1003 | i_mmap_unlock_read(mapping); |
2b144498 | 1004 | |
26872090 ON |
1005 | if (!more) |
1006 | goto out; | |
1007 | ||
1008 | prev = curr; | |
1009 | while (curr) { | |
1010 | mmput(curr->mm); | |
1011 | curr = curr->next; | |
1012 | } | |
7b2d81d4 | 1013 | |
26872090 ON |
1014 | do { |
1015 | info = kmalloc(sizeof(struct map_info), GFP_KERNEL); | |
1016 | if (!info) { | |
1017 | curr = ERR_PTR(-ENOMEM); | |
1018 | goto out; | |
1019 | } | |
1020 | info->next = prev; | |
1021 | prev = info; | |
1022 | } while (--more); | |
1023 | ||
1024 | goto again; | |
1025 | out: | |
1026 | while (prev) | |
1027 | prev = free_map_info(prev); | |
1028 | return curr; | |
2b144498 SD |
1029 | } |
1030 | ||
bdf8647c ON |
1031 | static int |
1032 | register_for_each_vma(struct uprobe *uprobe, struct uprobe_consumer *new) | |
2b144498 | 1033 | { |
bdf8647c | 1034 | bool is_register = !!new; |
26872090 ON |
1035 | struct map_info *info; |
1036 | int err = 0; | |
2b144498 | 1037 | |
32cdba1e | 1038 | percpu_down_write(&dup_mmap_sem); |
26872090 ON |
1039 | info = build_map_info(uprobe->inode->i_mapping, |
1040 | uprobe->offset, is_register); | |
32cdba1e ON |
1041 | if (IS_ERR(info)) { |
1042 | err = PTR_ERR(info); | |
1043 | goto out; | |
1044 | } | |
7b2d81d4 | 1045 | |
26872090 ON |
1046 | while (info) { |
1047 | struct mm_struct *mm = info->mm; | |
1048 | struct vm_area_struct *vma; | |
7b2d81d4 | 1049 | |
076a365b | 1050 | if (err && is_register) |
26872090 | 1051 | goto free; |
7b2d81d4 | 1052 | |
d8ed45c5 | 1053 | mmap_write_lock(mm); |
f4d6dfe5 ON |
1054 | vma = find_vma(mm, info->vaddr); |
1055 | if (!vma || !valid_vma(vma, is_register) || | |
f281769e | 1056 | file_inode(vma->vm_file) != uprobe->inode) |
26872090 ON |
1057 | goto unlock; |
1058 | ||
f4d6dfe5 ON |
1059 | if (vma->vm_start > info->vaddr || |
1060 | vaddr_to_offset(vma, info->vaddr) != uprobe->offset) | |
26872090 | 1061 | goto unlock; |
2b144498 | 1062 | |
806a98bd ON |
1063 | if (is_register) { |
1064 | /* consult only the "caller", new consumer. */ | |
bdf8647c | 1065 | if (consumer_filter(new, |
8a7f2fa0 | 1066 | UPROBE_FILTER_REGISTER, mm)) |
806a98bd ON |
1067 | err = install_breakpoint(uprobe, mm, vma, info->vaddr); |
1068 | } else if (test_bit(MMF_HAS_UPROBES, &mm->flags)) { | |
8a7f2fa0 ON |
1069 | if (!filter_chain(uprobe, |
1070 | UPROBE_FILTER_UNREGISTER, mm)) | |
806a98bd ON |
1071 | err |= remove_breakpoint(uprobe, mm, info->vaddr); |
1072 | } | |
78f74116 | 1073 | |
26872090 | 1074 | unlock: |
d8ed45c5 | 1075 | mmap_write_unlock(mm); |
26872090 ON |
1076 | free: |
1077 | mmput(mm); | |
1078 | info = free_map_info(info); | |
2b144498 | 1079 | } |
32cdba1e ON |
1080 | out: |
1081 | percpu_up_write(&dup_mmap_sem); | |
26872090 | 1082 | return err; |
2b144498 SD |
1083 | } |
1084 | ||
38e967ae RB |
1085 | static void |
1086 | __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc) | |
2b144498 | 1087 | { |
04aab9b2 ON |
1088 | int err; |
1089 | ||
06d07139 | 1090 | if (WARN_ON(!consumer_del(uprobe, uc))) |
04aab9b2 | 1091 | return; |
2b144498 | 1092 | |
bdf8647c | 1093 | err = register_for_each_vma(uprobe, NULL); |
bb929284 ON |
1094 | /* TODO : cant unregister? schedule a worker thread */ |
1095 | if (!uprobe->consumers && !err) | |
1096 | delete_uprobe(uprobe); | |
2b144498 SD |
1097 | } |
1098 | ||
1099 | /* | |
7140ad38 | 1100 | * uprobe_unregister - unregister an already registered probe. |
38e967ae RB |
1101 | * @inode: the file in which the probe has to be removed. |
1102 | * @offset: offset from the start of the file. | |
1103 | * @uc: identify which probe if multiple probes are colocated. | |
1104 | */ | |
1105 | void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) | |
1106 | { | |
1107 | struct uprobe *uprobe; | |
1108 | ||
1109 | uprobe = find_uprobe(inode, offset); | |
1110 | if (WARN_ON(!uprobe)) | |
1111 | return; | |
1112 | ||
1113 | down_write(&uprobe->register_rwsem); | |
1114 | __uprobe_unregister(uprobe, uc); | |
1115 | up_write(&uprobe->register_rwsem); | |
1116 | put_uprobe(uprobe); | |
1117 | } | |
1118 | EXPORT_SYMBOL_GPL(uprobe_unregister); | |
1119 | ||
1120 | /* | |
1121 | * __uprobe_register - register a probe | |
2b144498 SD |
1122 | * @inode: the file in which the probe has to be placed. |
1123 | * @offset: offset from the start of the file. | |
e3343e6a | 1124 | * @uc: information on howto handle the probe.. |
2b144498 | 1125 | * |
38e967ae | 1126 | * Apart from the access refcount, __uprobe_register() takes a creation |
2b144498 SD |
1127 | * refcount (thro alloc_uprobe) if and only if this @uprobe is getting |
1128 | * inserted into the rbtree (i.e first consumer for a @inode:@offset | |
7b2d81d4 | 1129 | * tuple). Creation refcount stops uprobe_unregister from freeing the |
2b144498 | 1130 | * @uprobe even before the register operation is complete. Creation |
e3343e6a | 1131 | * refcount is released when the last @uc for the @uprobe |
38e967ae | 1132 | * unregisters. Caller of __uprobe_register() is required to keep @inode |
61f94203 | 1133 | * (and the containing mount) referenced. |
2b144498 SD |
1134 | * |
1135 | * Return errno if it cannot successully install probes | |
1136 | * else return 0 (success) | |
1137 | */ | |
38e967ae | 1138 | static int __uprobe_register(struct inode *inode, loff_t offset, |
1cc33161 | 1139 | loff_t ref_ctr_offset, struct uprobe_consumer *uc) |
2b144498 SD |
1140 | { |
1141 | struct uprobe *uprobe; | |
7b2d81d4 | 1142 | int ret; |
2b144498 | 1143 | |
ea024870 AA |
1144 | /* Uprobe must have at least one set consumer */ |
1145 | if (!uc->handler && !uc->ret_handler) | |
1146 | return -EINVAL; | |
1147 | ||
40814f68 | 1148 | /* copy_insn() uses read_mapping_page() or shmem_read_mapping_page() */ |
5efe7448 | 1149 | if (!inode->i_mapping->a_ops->read_folio && |
5efe7448 | 1150 | !shmem_mapping(inode->i_mapping)) |
41ccba02 | 1151 | return -EIO; |
f0744af7 | 1152 | /* Racy, just to catch the obvious mistakes */ |
2b144498 | 1153 | if (offset > i_size_read(inode)) |
7b2d81d4 | 1154 | return -EINVAL; |
2b144498 | 1155 | |
013b2deb ON |
1156 | /* |
1157 | * This ensures that copy_from_page(), copy_to_page() and | |
1158 | * __update_ref_ctr() can't cross page boundary. | |
1159 | */ | |
1160 | if (!IS_ALIGNED(offset, UPROBE_SWBP_INSN_SIZE)) | |
1161 | return -EINVAL; | |
1162 | if (!IS_ALIGNED(ref_ctr_offset, sizeof(short))) | |
1163 | return -EINVAL; | |
1164 | ||
66d06dff | 1165 | retry: |
1cc33161 | 1166 | uprobe = alloc_uprobe(inode, offset, ref_ctr_offset); |
66d06dff ON |
1167 | if (!uprobe) |
1168 | return -ENOMEM; | |
22bad382 RB |
1169 | if (IS_ERR(uprobe)) |
1170 | return PTR_ERR(uprobe); | |
1171 | ||
66d06dff ON |
1172 | /* |
1173 | * We can race with uprobe_unregister()->delete_uprobe(). | |
1174 | * Check uprobe_is_active() and retry if it is false. | |
1175 | */ | |
1176 | down_write(&uprobe->register_rwsem); | |
1177 | ret = -EAGAIN; | |
1178 | if (likely(uprobe_is_active(uprobe))) { | |
38e967ae RB |
1179 | consumer_add(uprobe, uc); |
1180 | ret = register_for_each_vma(uprobe, uc); | |
9a98e03c | 1181 | if (ret) |
04aab9b2 | 1182 | __uprobe_unregister(uprobe, uc); |
2b144498 | 1183 | } |
66d06dff ON |
1184 | up_write(&uprobe->register_rwsem); |
1185 | put_uprobe(uprobe); | |
2b144498 | 1186 | |
66d06dff ON |
1187 | if (unlikely(ret == -EAGAIN)) |
1188 | goto retry; | |
2b144498 SD |
1189 | return ret; |
1190 | } | |
38e967ae RB |
1191 | |
1192 | int uprobe_register(struct inode *inode, loff_t offset, | |
1193 | struct uprobe_consumer *uc) | |
1194 | { | |
1cc33161 | 1195 | return __uprobe_register(inode, offset, 0, uc); |
38e967ae | 1196 | } |
e8440c14 | 1197 | EXPORT_SYMBOL_GPL(uprobe_register); |
2b144498 | 1198 | |
1cc33161 RB |
1199 | int uprobe_register_refctr(struct inode *inode, loff_t offset, |
1200 | loff_t ref_ctr_offset, struct uprobe_consumer *uc) | |
1201 | { | |
1202 | return __uprobe_register(inode, offset, ref_ctr_offset, uc); | |
1203 | } | |
1204 | EXPORT_SYMBOL_GPL(uprobe_register_refctr); | |
1205 | ||
bdf8647c | 1206 | /* |
788faab7 | 1207 | * uprobe_apply - unregister an already registered probe. |
bdf8647c ON |
1208 | * @inode: the file in which the probe has to be removed. |
1209 | * @offset: offset from the start of the file. | |
1210 | * @uc: consumer which wants to add more or remove some breakpoints | |
1211 | * @add: add or remove the breakpoints | |
1212 | */ | |
1213 | int uprobe_apply(struct inode *inode, loff_t offset, | |
1214 | struct uprobe_consumer *uc, bool add) | |
1215 | { | |
1216 | struct uprobe *uprobe; | |
1217 | struct uprobe_consumer *con; | |
1218 | int ret = -ENOENT; | |
1219 | ||
1220 | uprobe = find_uprobe(inode, offset); | |
06d07139 | 1221 | if (WARN_ON(!uprobe)) |
bdf8647c ON |
1222 | return ret; |
1223 | ||
1224 | down_write(&uprobe->register_rwsem); | |
1225 | for (con = uprobe->consumers; con && con != uc ; con = con->next) | |
1226 | ; | |
1227 | if (con) | |
1228 | ret = register_for_each_vma(uprobe, add ? uc : NULL); | |
1229 | up_write(&uprobe->register_rwsem); | |
1230 | put_uprobe(uprobe); | |
1231 | ||
1232 | return ret; | |
1233 | } | |
1234 | ||
da1816b1 ON |
1235 | static int unapply_uprobe(struct uprobe *uprobe, struct mm_struct *mm) |
1236 | { | |
fcb72a58 | 1237 | VMA_ITERATOR(vmi, mm, 0); |
da1816b1 ON |
1238 | struct vm_area_struct *vma; |
1239 | int err = 0; | |
1240 | ||
d8ed45c5 | 1241 | mmap_read_lock(mm); |
fcb72a58 | 1242 | for_each_vma(vmi, vma) { |
da1816b1 ON |
1243 | unsigned long vaddr; |
1244 | loff_t offset; | |
1245 | ||
1246 | if (!valid_vma(vma, false) || | |
f281769e | 1247 | file_inode(vma->vm_file) != uprobe->inode) |
da1816b1 ON |
1248 | continue; |
1249 | ||
1250 | offset = (loff_t)vma->vm_pgoff << PAGE_SHIFT; | |
1251 | if (uprobe->offset < offset || | |
1252 | uprobe->offset >= offset + vma->vm_end - vma->vm_start) | |
1253 | continue; | |
1254 | ||
1255 | vaddr = offset_to_vaddr(vma, uprobe->offset); | |
1256 | err |= remove_breakpoint(uprobe, mm, vaddr); | |
1257 | } | |
d8ed45c5 | 1258 | mmap_read_unlock(mm); |
da1816b1 ON |
1259 | |
1260 | return err; | |
1261 | } | |
1262 | ||
891c3970 ON |
1263 | static struct rb_node * |
1264 | find_node_in_range(struct inode *inode, loff_t min, loff_t max) | |
2b144498 | 1265 | { |
2b144498 | 1266 | struct rb_node *n = uprobes_tree.rb_node; |
2b144498 SD |
1267 | |
1268 | while (n) { | |
891c3970 | 1269 | struct uprobe *u = rb_entry(n, struct uprobe, rb_node); |
2b144498 | 1270 | |
891c3970 | 1271 | if (inode < u->inode) { |
2b144498 | 1272 | n = n->rb_left; |
891c3970 | 1273 | } else if (inode > u->inode) { |
2b144498 | 1274 | n = n->rb_right; |
891c3970 ON |
1275 | } else { |
1276 | if (max < u->offset) | |
1277 | n = n->rb_left; | |
1278 | else if (min > u->offset) | |
1279 | n = n->rb_right; | |
1280 | else | |
1281 | break; | |
1282 | } | |
2b144498 | 1283 | } |
7b2d81d4 | 1284 | |
891c3970 | 1285 | return n; |
2b144498 SD |
1286 | } |
1287 | ||
1288 | /* | |
891c3970 | 1289 | * For a given range in vma, build a list of probes that need to be inserted. |
2b144498 | 1290 | */ |
891c3970 ON |
1291 | static void build_probe_list(struct inode *inode, |
1292 | struct vm_area_struct *vma, | |
1293 | unsigned long start, unsigned long end, | |
1294 | struct list_head *head) | |
2b144498 | 1295 | { |
891c3970 | 1296 | loff_t min, max; |
891c3970 ON |
1297 | struct rb_node *n, *t; |
1298 | struct uprobe *u; | |
7b2d81d4 | 1299 | |
891c3970 | 1300 | INIT_LIST_HEAD(head); |
cb113b47 | 1301 | min = vaddr_to_offset(vma, start); |
891c3970 | 1302 | max = min + (end - start) - 1; |
2b144498 | 1303 | |
6f47caa0 | 1304 | spin_lock(&uprobes_treelock); |
891c3970 ON |
1305 | n = find_node_in_range(inode, min, max); |
1306 | if (n) { | |
1307 | for (t = n; t; t = rb_prev(t)) { | |
1308 | u = rb_entry(t, struct uprobe, rb_node); | |
1309 | if (u->inode != inode || u->offset < min) | |
1310 | break; | |
1311 | list_add(&u->pending_list, head); | |
f231722a | 1312 | get_uprobe(u); |
891c3970 ON |
1313 | } |
1314 | for (t = n; (t = rb_next(t)); ) { | |
1315 | u = rb_entry(t, struct uprobe, rb_node); | |
1316 | if (u->inode != inode || u->offset > max) | |
1317 | break; | |
1318 | list_add(&u->pending_list, head); | |
f231722a | 1319 | get_uprobe(u); |
891c3970 | 1320 | } |
2b144498 | 1321 | } |
6f47caa0 | 1322 | spin_unlock(&uprobes_treelock); |
2b144498 SD |
1323 | } |
1324 | ||
1cc33161 RB |
1325 | /* @vma contains reference counter, not the probed instruction. */ |
1326 | static int delayed_ref_ctr_inc(struct vm_area_struct *vma) | |
1327 | { | |
1328 | struct list_head *pos, *q; | |
1329 | struct delayed_uprobe *du; | |
1330 | unsigned long vaddr; | |
1331 | int ret = 0, err = 0; | |
1332 | ||
1333 | mutex_lock(&delayed_uprobe_lock); | |
1334 | list_for_each_safe(pos, q, &delayed_uprobe_list) { | |
1335 | du = list_entry(pos, struct delayed_uprobe, list); | |
1336 | ||
1337 | if (du->mm != vma->vm_mm || | |
1338 | !valid_ref_ctr_vma(du->uprobe, vma)) | |
1339 | continue; | |
1340 | ||
1341 | vaddr = offset_to_vaddr(vma, du->uprobe->ref_ctr_offset); | |
1342 | ret = __update_ref_ctr(vma->vm_mm, vaddr, 1); | |
1343 | if (ret) { | |
1344 | update_ref_ctr_warn(du->uprobe, vma->vm_mm, 1); | |
1345 | if (!err) | |
1346 | err = ret; | |
1347 | } | |
1348 | delayed_uprobe_delete(du); | |
1349 | } | |
1350 | mutex_unlock(&delayed_uprobe_lock); | |
1351 | return err; | |
1352 | } | |
1353 | ||
2b144498 | 1354 | /* |
c1e8d7c6 | 1355 | * Called from mmap_region/vma_adjust with mm->mmap_lock acquired. |
2b144498 | 1356 | * |
5e5be71a ON |
1357 | * Currently we ignore all errors and always return 0, the callers |
1358 | * can't handle the failure anyway. | |
2b144498 | 1359 | */ |
7b2d81d4 | 1360 | int uprobe_mmap(struct vm_area_struct *vma) |
2b144498 SD |
1361 | { |
1362 | struct list_head tmp_list; | |
665605a2 | 1363 | struct uprobe *uprobe, *u; |
2b144498 | 1364 | struct inode *inode; |
2b144498 | 1365 | |
1cc33161 RB |
1366 | if (no_uprobe_events()) |
1367 | return 0; | |
1368 | ||
1369 | if (vma->vm_file && | |
1370 | (vma->vm_flags & (VM_WRITE|VM_SHARED)) == VM_WRITE && | |
1371 | test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags)) | |
1372 | delayed_ref_ctr_inc(vma); | |
1373 | ||
1374 | if (!valid_vma(vma, true)) | |
7b2d81d4 | 1375 | return 0; |
2b144498 | 1376 | |
f281769e | 1377 | inode = file_inode(vma->vm_file); |
2b144498 | 1378 | if (!inode) |
7b2d81d4 | 1379 | return 0; |
2b144498 | 1380 | |
2b144498 | 1381 | mutex_lock(uprobes_mmap_hash(inode)); |
891c3970 | 1382 | build_probe_list(inode, vma, vma->vm_start, vma->vm_end, &tmp_list); |
806a98bd ON |
1383 | /* |
1384 | * We can race with uprobe_unregister(), this uprobe can be already | |
1385 | * removed. But in this case filter_chain() must return false, all | |
1386 | * consumers have gone away. | |
1387 | */ | |
665605a2 | 1388 | list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) { |
806a98bd | 1389 | if (!fatal_signal_pending(current) && |
8a7f2fa0 | 1390 | filter_chain(uprobe, UPROBE_FILTER_MMAP, vma->vm_mm)) { |
57683f72 | 1391 | unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset); |
5e5be71a | 1392 | install_breakpoint(uprobe, vma->vm_mm, vma, vaddr); |
2b144498 SD |
1393 | } |
1394 | put_uprobe(uprobe); | |
1395 | } | |
2b144498 SD |
1396 | mutex_unlock(uprobes_mmap_hash(inode)); |
1397 | ||
5e5be71a | 1398 | return 0; |
2b144498 SD |
1399 | } |
1400 | ||
9f68f672 ON |
1401 | static bool |
1402 | vma_has_uprobes(struct vm_area_struct *vma, unsigned long start, unsigned long end) | |
1403 | { | |
1404 | loff_t min, max; | |
1405 | struct inode *inode; | |
1406 | struct rb_node *n; | |
1407 | ||
f281769e | 1408 | inode = file_inode(vma->vm_file); |
9f68f672 ON |
1409 | |
1410 | min = vaddr_to_offset(vma, start); | |
1411 | max = min + (end - start) - 1; | |
1412 | ||
1413 | spin_lock(&uprobes_treelock); | |
1414 | n = find_node_in_range(inode, min, max); | |
1415 | spin_unlock(&uprobes_treelock); | |
1416 | ||
1417 | return !!n; | |
1418 | } | |
1419 | ||
682968e0 SD |
1420 | /* |
1421 | * Called in context of a munmap of a vma. | |
1422 | */ | |
cbc91f71 | 1423 | void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end) |
682968e0 | 1424 | { |
441f1eb7 | 1425 | if (no_uprobe_events() || !valid_vma(vma, false)) |
682968e0 SD |
1426 | return; |
1427 | ||
2fd611a9 ON |
1428 | if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */ |
1429 | return; | |
1430 | ||
9f68f672 ON |
1431 | if (!test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags) || |
1432 | test_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags)) | |
f8ac4ec9 ON |
1433 | return; |
1434 | ||
9f68f672 ON |
1435 | if (vma_has_uprobes(vma, start, end)) |
1436 | set_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags); | |
682968e0 SD |
1437 | } |
1438 | ||
d4b3b638 | 1439 | /* Slot allocation for XOL */ |
6441ec8b | 1440 | static int xol_add_vma(struct mm_struct *mm, struct xol_area *area) |
d4b3b638 | 1441 | { |
704bde3c ON |
1442 | struct vm_area_struct *vma; |
1443 | int ret; | |
d4b3b638 | 1444 | |
d8ed45c5 | 1445 | if (mmap_write_lock_killable(mm)) |
598fdc1d MH |
1446 | return -EINTR; |
1447 | ||
704bde3c ON |
1448 | if (mm->uprobes_state.xol_area) { |
1449 | ret = -EALREADY; | |
d4b3b638 | 1450 | goto fail; |
704bde3c | 1451 | } |
d4b3b638 | 1452 | |
af0d95af ON |
1453 | if (!area->vaddr) { |
1454 | /* Try to map as high as possible, this is only a hint. */ | |
1455 | area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE, | |
1456 | PAGE_SIZE, 0, 0); | |
ff68dac6 | 1457 | if (IS_ERR_VALUE(area->vaddr)) { |
af0d95af ON |
1458 | ret = area->vaddr; |
1459 | goto fail; | |
1460 | } | |
d4b3b638 SD |
1461 | } |
1462 | ||
704bde3c ON |
1463 | vma = _install_special_mapping(mm, area->vaddr, PAGE_SIZE, |
1464 | VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO, | |
1465 | &area->xol_mapping); | |
1466 | if (IS_ERR(vma)) { | |
1467 | ret = PTR_ERR(vma); | |
d4b3b638 | 1468 | goto fail; |
704bde3c | 1469 | } |
d4b3b638 | 1470 | |
704bde3c | 1471 | ret = 0; |
5c6338b4 PM |
1472 | /* pairs with get_xol_area() */ |
1473 | smp_store_release(&mm->uprobes_state.xol_area, area); /* ^^^ */ | |
c8a82538 | 1474 | fail: |
d8ed45c5 | 1475 | mmap_write_unlock(mm); |
d4b3b638 SD |
1476 | |
1477 | return ret; | |
1478 | } | |
1479 | ||
af0d95af | 1480 | static struct xol_area *__create_xol_area(unsigned long vaddr) |
d4b3b638 | 1481 | { |
9b545df8 | 1482 | struct mm_struct *mm = current->mm; |
e78aebfd | 1483 | uprobe_opcode_t insn = UPROBE_SWBP_INSN; |
6441ec8b | 1484 | struct xol_area *area; |
9b545df8 | 1485 | |
af0d95af | 1486 | area = kmalloc(sizeof(*area), GFP_KERNEL); |
d4b3b638 | 1487 | if (unlikely(!area)) |
c8a82538 | 1488 | goto out; |
d4b3b638 | 1489 | |
6396bb22 KC |
1490 | area->bitmap = kcalloc(BITS_TO_LONGS(UINSNS_PER_PAGE), sizeof(long), |
1491 | GFP_KERNEL); | |
d4b3b638 | 1492 | if (!area->bitmap) |
c8a82538 ON |
1493 | goto free_area; |
1494 | ||
704bde3c | 1495 | area->xol_mapping.name = "[uprobes]"; |
869ae761 | 1496 | area->xol_mapping.fault = NULL; |
704bde3c | 1497 | area->xol_mapping.pages = area->pages; |
f58bea2f ON |
1498 | area->pages[0] = alloc_page(GFP_HIGHUSER); |
1499 | if (!area->pages[0]) | |
c8a82538 | 1500 | goto free_bitmap; |
f58bea2f | 1501 | area->pages[1] = NULL; |
d4b3b638 | 1502 | |
af0d95af | 1503 | area->vaddr = vaddr; |
6441ec8b ON |
1504 | init_waitqueue_head(&area->wq); |
1505 | /* Reserve the 1st slot for get_trampoline_vaddr() */ | |
e78aebfd | 1506 | set_bit(0, area->bitmap); |
e78aebfd | 1507 | atomic_set(&area->slot_count, 1); |
297e765e | 1508 | arch_uprobe_copy_ixol(area->pages[0], 0, &insn, UPROBE_SWBP_INSN_SIZE); |
e78aebfd | 1509 | |
6441ec8b | 1510 | if (!xol_add_vma(mm, area)) |
d4b3b638 SD |
1511 | return area; |
1512 | ||
f58bea2f | 1513 | __free_page(area->pages[0]); |
c8a82538 | 1514 | free_bitmap: |
d4b3b638 | 1515 | kfree(area->bitmap); |
c8a82538 | 1516 | free_area: |
d4b3b638 | 1517 | kfree(area); |
c8a82538 | 1518 | out: |
6441ec8b ON |
1519 | return NULL; |
1520 | } | |
1521 | ||
1522 | /* | |
1523 | * get_xol_area - Allocate process's xol_area if necessary. | |
1524 | * This area will be used for storing instructions for execution out of line. | |
1525 | * | |
1526 | * Returns the allocated area or NULL. | |
1527 | */ | |
1528 | static struct xol_area *get_xol_area(void) | |
1529 | { | |
1530 | struct mm_struct *mm = current->mm; | |
1531 | struct xol_area *area; | |
1532 | ||
1533 | if (!mm->uprobes_state.xol_area) | |
af0d95af | 1534 | __create_xol_area(0); |
6441ec8b | 1535 | |
5c6338b4 PM |
1536 | /* Pairs with xol_add_vma() smp_store_release() */ |
1537 | area = READ_ONCE(mm->uprobes_state.xol_area); /* ^^^ */ | |
9b545df8 | 1538 | return area; |
d4b3b638 SD |
1539 | } |
1540 | ||
1541 | /* | |
1542 | * uprobe_clear_state - Free the area allocated for slots. | |
1543 | */ | |
1544 | void uprobe_clear_state(struct mm_struct *mm) | |
1545 | { | |
1546 | struct xol_area *area = mm->uprobes_state.xol_area; | |
1547 | ||
1cc33161 RB |
1548 | mutex_lock(&delayed_uprobe_lock); |
1549 | delayed_uprobe_remove(NULL, mm); | |
1550 | mutex_unlock(&delayed_uprobe_lock); | |
1551 | ||
d4b3b638 SD |
1552 | if (!area) |
1553 | return; | |
1554 | ||
f58bea2f | 1555 | put_page(area->pages[0]); |
d4b3b638 SD |
1556 | kfree(area->bitmap); |
1557 | kfree(area); | |
1558 | } | |
1559 | ||
32cdba1e ON |
1560 | void uprobe_start_dup_mmap(void) |
1561 | { | |
1562 | percpu_down_read(&dup_mmap_sem); | |
1563 | } | |
1564 | ||
1565 | void uprobe_end_dup_mmap(void) | |
1566 | { | |
1567 | percpu_up_read(&dup_mmap_sem); | |
1568 | } | |
1569 | ||
f8ac4ec9 ON |
1570 | void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm) |
1571 | { | |
9f68f672 | 1572 | if (test_bit(MMF_HAS_UPROBES, &oldmm->flags)) { |
f8ac4ec9 | 1573 | set_bit(MMF_HAS_UPROBES, &newmm->flags); |
9f68f672 ON |
1574 | /* unconditionally, dup_mmap() skips VM_DONTCOPY vmas */ |
1575 | set_bit(MMF_RECALC_UPROBES, &newmm->flags); | |
1576 | } | |
f8ac4ec9 ON |
1577 | } |
1578 | ||
d4b3b638 SD |
1579 | /* |
1580 | * - search for a free slot. | |
1581 | */ | |
1582 | static unsigned long xol_take_insn_slot(struct xol_area *area) | |
1583 | { | |
1584 | unsigned long slot_addr; | |
1585 | int slot_nr; | |
1586 | ||
1587 | do { | |
1588 | slot_nr = find_first_zero_bit(area->bitmap, UINSNS_PER_PAGE); | |
1589 | if (slot_nr < UINSNS_PER_PAGE) { | |
1590 | if (!test_and_set_bit(slot_nr, area->bitmap)) | |
1591 | break; | |
1592 | ||
1593 | slot_nr = UINSNS_PER_PAGE; | |
1594 | continue; | |
1595 | } | |
1596 | wait_event(area->wq, (atomic_read(&area->slot_count) < UINSNS_PER_PAGE)); | |
1597 | } while (slot_nr >= UINSNS_PER_PAGE); | |
1598 | ||
1599 | slot_addr = area->vaddr + (slot_nr * UPROBE_XOL_SLOT_BYTES); | |
1600 | atomic_inc(&area->slot_count); | |
1601 | ||
1602 | return slot_addr; | |
1603 | } | |
1604 | ||
1605 | /* | |
a6cb3f6d | 1606 | * xol_get_insn_slot - allocate a slot for xol. |
d4b3b638 SD |
1607 | * Returns the allocated slot address or 0. |
1608 | */ | |
a6cb3f6d | 1609 | static unsigned long xol_get_insn_slot(struct uprobe *uprobe) |
d4b3b638 SD |
1610 | { |
1611 | struct xol_area *area; | |
a6cb3f6d | 1612 | unsigned long xol_vaddr; |
d4b3b638 | 1613 | |
9b545df8 ON |
1614 | area = get_xol_area(); |
1615 | if (!area) | |
1616 | return 0; | |
d4b3b638 | 1617 | |
a6cb3f6d ON |
1618 | xol_vaddr = xol_take_insn_slot(area); |
1619 | if (unlikely(!xol_vaddr)) | |
d4b3b638 SD |
1620 | return 0; |
1621 | ||
f58bea2f | 1622 | arch_uprobe_copy_ixol(area->pages[0], xol_vaddr, |
72e6ae28 | 1623 | &uprobe->arch.ixol, sizeof(uprobe->arch.ixol)); |
d4b3b638 | 1624 | |
a6cb3f6d | 1625 | return xol_vaddr; |
d4b3b638 SD |
1626 | } |
1627 | ||
1628 | /* | |
1629 | * xol_free_insn_slot - If slot was earlier allocated by | |
1630 | * @xol_get_insn_slot(), make the slot available for | |
1631 | * subsequent requests. | |
1632 | */ | |
1633 | static void xol_free_insn_slot(struct task_struct *tsk) | |
1634 | { | |
1635 | struct xol_area *area; | |
1636 | unsigned long vma_end; | |
1637 | unsigned long slot_addr; | |
1638 | ||
1639 | if (!tsk->mm || !tsk->mm->uprobes_state.xol_area || !tsk->utask) | |
1640 | return; | |
1641 | ||
1642 | slot_addr = tsk->utask->xol_vaddr; | |
af4355e9 | 1643 | if (unlikely(!slot_addr)) |
d4b3b638 SD |
1644 | return; |
1645 | ||
1646 | area = tsk->mm->uprobes_state.xol_area; | |
1647 | vma_end = area->vaddr + PAGE_SIZE; | |
1648 | if (area->vaddr <= slot_addr && slot_addr < vma_end) { | |
1649 | unsigned long offset; | |
1650 | int slot_nr; | |
1651 | ||
1652 | offset = slot_addr - area->vaddr; | |
1653 | slot_nr = offset / UPROBE_XOL_SLOT_BYTES; | |
1654 | if (slot_nr >= UINSNS_PER_PAGE) | |
1655 | return; | |
1656 | ||
1657 | clear_bit(slot_nr, area->bitmap); | |
1658 | atomic_dec(&area->slot_count); | |
2a742ced | 1659 | smp_mb__after_atomic(); /* pairs with prepare_to_wait() */ |
d4b3b638 SD |
1660 | if (waitqueue_active(&area->wq)) |
1661 | wake_up(&area->wq); | |
1662 | ||
1663 | tsk->utask->xol_vaddr = 0; | |
1664 | } | |
1665 | } | |
1666 | ||
72e6ae28 VK |
1667 | void __weak arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr, |
1668 | void *src, unsigned long len) | |
1669 | { | |
1670 | /* Initialize the slot */ | |
1671 | copy_to_page(page, vaddr, src, len); | |
1672 | ||
1673 | /* | |
885f7f8e | 1674 | * We probably need flush_icache_user_page() but it needs vma. |
72e6ae28 VK |
1675 | * This should work on most of architectures by default. If |
1676 | * architecture needs to do something different it can define | |
1677 | * its own version of the function. | |
1678 | */ | |
1679 | flush_dcache_page(page); | |
1680 | } | |
1681 | ||
0326f5a9 SD |
1682 | /** |
1683 | * uprobe_get_swbp_addr - compute address of swbp given post-swbp regs | |
1684 | * @regs: Reflects the saved state of the task after it has hit a breakpoint | |
1685 | * instruction. | |
1686 | * Return the address of the breakpoint instruction. | |
1687 | */ | |
1688 | unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs) | |
1689 | { | |
1690 | return instruction_pointer(regs) - UPROBE_SWBP_INSN_SIZE; | |
1691 | } | |
1692 | ||
b02ef20a ON |
1693 | unsigned long uprobe_get_trap_addr(struct pt_regs *regs) |
1694 | { | |
1695 | struct uprobe_task *utask = current->utask; | |
1696 | ||
1697 | if (unlikely(utask && utask->active_uprobe)) | |
1698 | return utask->vaddr; | |
1699 | ||
1700 | return instruction_pointer(regs); | |
1701 | } | |
1702 | ||
2bb5e840 ON |
1703 | static struct return_instance *free_ret_instance(struct return_instance *ri) |
1704 | { | |
1705 | struct return_instance *next = ri->next; | |
1706 | put_uprobe(ri->uprobe); | |
1707 | kfree(ri); | |
1708 | return next; | |
1709 | } | |
1710 | ||
0326f5a9 SD |
1711 | /* |
1712 | * Called with no locks held. | |
788faab7 | 1713 | * Called in context of an exiting or an exec-ing thread. |
0326f5a9 SD |
1714 | */ |
1715 | void uprobe_free_utask(struct task_struct *t) | |
1716 | { | |
1717 | struct uprobe_task *utask = t->utask; | |
2bb5e840 | 1718 | struct return_instance *ri; |
0326f5a9 | 1719 | |
0326f5a9 SD |
1720 | if (!utask) |
1721 | return; | |
1722 | ||
1723 | if (utask->active_uprobe) | |
1724 | put_uprobe(utask->active_uprobe); | |
1725 | ||
0dfd0eb8 | 1726 | ri = utask->return_instances; |
2bb5e840 ON |
1727 | while (ri) |
1728 | ri = free_ret_instance(ri); | |
0dfd0eb8 | 1729 | |
d4b3b638 | 1730 | xol_free_insn_slot(t); |
0326f5a9 SD |
1731 | kfree(utask); |
1732 | t->utask = NULL; | |
1733 | } | |
1734 | ||
0326f5a9 | 1735 | /* |
c034f48e | 1736 | * Allocate a uprobe_task object for the task if necessary. |
5a2df662 | 1737 | * Called when the thread hits a breakpoint. |
0326f5a9 SD |
1738 | * |
1739 | * Returns: | |
1740 | * - pointer to new uprobe_task on success | |
1741 | * - NULL otherwise | |
1742 | */ | |
5a2df662 | 1743 | static struct uprobe_task *get_utask(void) |
0326f5a9 | 1744 | { |
5a2df662 ON |
1745 | if (!current->utask) |
1746 | current->utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL); | |
1747 | return current->utask; | |
0326f5a9 SD |
1748 | } |
1749 | ||
248d3a7b ON |
1750 | static int dup_utask(struct task_struct *t, struct uprobe_task *o_utask) |
1751 | { | |
1752 | struct uprobe_task *n_utask; | |
1753 | struct return_instance **p, *o, *n; | |
1754 | ||
1755 | n_utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL); | |
1756 | if (!n_utask) | |
1757 | return -ENOMEM; | |
1758 | t->utask = n_utask; | |
1759 | ||
1760 | p = &n_utask->return_instances; | |
1761 | for (o = o_utask->return_instances; o; o = o->next) { | |
1762 | n = kmalloc(sizeof(struct return_instance), GFP_KERNEL); | |
1763 | if (!n) | |
1764 | return -ENOMEM; | |
1765 | ||
1766 | *n = *o; | |
f231722a | 1767 | get_uprobe(n->uprobe); |
248d3a7b ON |
1768 | n->next = NULL; |
1769 | ||
1770 | *p = n; | |
1771 | p = &n->next; | |
1772 | n_utask->depth++; | |
1773 | } | |
1774 | ||
1775 | return 0; | |
1776 | } | |
1777 | ||
1778 | static void uprobe_warn(struct task_struct *t, const char *msg) | |
1779 | { | |
1780 | pr_warn("uprobe: %s:%d failed to %s\n", | |
1781 | current->comm, current->pid, msg); | |
1782 | } | |
1783 | ||
aa59c53f ON |
1784 | static void dup_xol_work(struct callback_head *work) |
1785 | { | |
aa59c53f ON |
1786 | if (current->flags & PF_EXITING) |
1787 | return; | |
1788 | ||
598fdc1d MH |
1789 | if (!__create_xol_area(current->utask->dup_xol_addr) && |
1790 | !fatal_signal_pending(current)) | |
aa59c53f ON |
1791 | uprobe_warn(current, "dup xol area"); |
1792 | } | |
1793 | ||
b68e0749 ON |
1794 | /* |
1795 | * Called in context of a new clone/fork from copy_process. | |
1796 | */ | |
3ab67966 | 1797 | void uprobe_copy_process(struct task_struct *t, unsigned long flags) |
b68e0749 | 1798 | { |
248d3a7b ON |
1799 | struct uprobe_task *utask = current->utask; |
1800 | struct mm_struct *mm = current->mm; | |
aa59c53f | 1801 | struct xol_area *area; |
248d3a7b | 1802 | |
b68e0749 | 1803 | t->utask = NULL; |
248d3a7b | 1804 | |
3ab67966 ON |
1805 | if (!utask || !utask->return_instances) |
1806 | return; | |
1807 | ||
1808 | if (mm == t->mm && !(flags & CLONE_VFORK)) | |
248d3a7b ON |
1809 | return; |
1810 | ||
1811 | if (dup_utask(t, utask)) | |
1812 | return uprobe_warn(t, "dup ret instances"); | |
aa59c53f ON |
1813 | |
1814 | /* The task can fork() after dup_xol_work() fails */ | |
1815 | area = mm->uprobes_state.xol_area; | |
1816 | if (!area) | |
1817 | return uprobe_warn(t, "dup xol area"); | |
1818 | ||
3ab67966 ON |
1819 | if (mm == t->mm) |
1820 | return; | |
1821 | ||
32473431 ON |
1822 | t->utask->dup_xol_addr = area->vaddr; |
1823 | init_task_work(&t->utask->dup_xol_work, dup_xol_work); | |
91989c70 | 1824 | task_work_add(t, &t->utask->dup_xol_work, TWA_RESUME); |
b68e0749 ON |
1825 | } |
1826 | ||
e78aebfd AA |
1827 | /* |
1828 | * Current area->vaddr notion assume the trampoline address is always | |
1829 | * equal area->vaddr. | |
1830 | * | |
1831 | * Returns -1 in case the xol_area is not allocated. | |
1832 | */ | |
1833 | static unsigned long get_trampoline_vaddr(void) | |
1834 | { | |
1835 | struct xol_area *area; | |
1836 | unsigned long trampoline_vaddr = -1; | |
1837 | ||
5c6338b4 PM |
1838 | /* Pairs with xol_add_vma() smp_store_release() */ |
1839 | area = READ_ONCE(current->mm->uprobes_state.xol_area); /* ^^^ */ | |
e78aebfd AA |
1840 | if (area) |
1841 | trampoline_vaddr = area->vaddr; | |
1842 | ||
1843 | return trampoline_vaddr; | |
1844 | } | |
1845 | ||
db087ef6 ON |
1846 | static void cleanup_return_instances(struct uprobe_task *utask, bool chained, |
1847 | struct pt_regs *regs) | |
a5b7e1a8 ON |
1848 | { |
1849 | struct return_instance *ri = utask->return_instances; | |
db087ef6 | 1850 | enum rp_check ctx = chained ? RP_CHECK_CHAIN_CALL : RP_CHECK_CALL; |
86dcb702 ON |
1851 | |
1852 | while (ri && !arch_uretprobe_is_alive(ri, ctx, regs)) { | |
a5b7e1a8 ON |
1853 | ri = free_ret_instance(ri); |
1854 | utask->depth--; | |
1855 | } | |
1856 | utask->return_instances = ri; | |
1857 | } | |
1858 | ||
0dfd0eb8 AA |
1859 | static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs) |
1860 | { | |
1861 | struct return_instance *ri; | |
1862 | struct uprobe_task *utask; | |
1863 | unsigned long orig_ret_vaddr, trampoline_vaddr; | |
db087ef6 | 1864 | bool chained; |
0dfd0eb8 AA |
1865 | |
1866 | if (!get_xol_area()) | |
1867 | return; | |
1868 | ||
1869 | utask = get_utask(); | |
1870 | if (!utask) | |
1871 | return; | |
1872 | ||
ded49c55 AA |
1873 | if (utask->depth >= MAX_URETPROBE_DEPTH) { |
1874 | printk_ratelimited(KERN_INFO "uprobe: omit uretprobe due to" | |
1875 | " nestedness limit pid/tgid=%d/%d\n", | |
1876 | current->pid, current->tgid); | |
1877 | return; | |
1878 | } | |
1879 | ||
6c58d0e4 | 1880 | ri = kmalloc(sizeof(struct return_instance), GFP_KERNEL); |
0dfd0eb8 | 1881 | if (!ri) |
6c58d0e4 | 1882 | return; |
0dfd0eb8 AA |
1883 | |
1884 | trampoline_vaddr = get_trampoline_vaddr(); | |
1885 | orig_ret_vaddr = arch_uretprobe_hijack_return_addr(trampoline_vaddr, regs); | |
1886 | if (orig_ret_vaddr == -1) | |
1887 | goto fail; | |
1888 | ||
a5b7e1a8 | 1889 | /* drop the entries invalidated by longjmp() */ |
db087ef6 ON |
1890 | chained = (orig_ret_vaddr == trampoline_vaddr); |
1891 | cleanup_return_instances(utask, chained, regs); | |
a5b7e1a8 | 1892 | |
0dfd0eb8 AA |
1893 | /* |
1894 | * We don't want to keep trampoline address in stack, rather keep the | |
1895 | * original return address of first caller thru all the consequent | |
1896 | * instances. This also makes breakpoint unwrapping easier. | |
1897 | */ | |
db087ef6 | 1898 | if (chained) { |
0dfd0eb8 AA |
1899 | if (!utask->return_instances) { |
1900 | /* | |
1901 | * This situation is not possible. Likely we have an | |
1902 | * attack from user-space. | |
1903 | */ | |
6c58d0e4 | 1904 | uprobe_warn(current, "handle tail call"); |
0dfd0eb8 AA |
1905 | goto fail; |
1906 | } | |
0dfd0eb8 AA |
1907 | orig_ret_vaddr = utask->return_instances->orig_ret_vaddr; |
1908 | } | |
1909 | ||
f231722a | 1910 | ri->uprobe = get_uprobe(uprobe); |
0dfd0eb8 | 1911 | ri->func = instruction_pointer(regs); |
7b868e48 | 1912 | ri->stack = user_stack_pointer(regs); |
0dfd0eb8 AA |
1913 | ri->orig_ret_vaddr = orig_ret_vaddr; |
1914 | ri->chained = chained; | |
1915 | ||
ded49c55 | 1916 | utask->depth++; |
0dfd0eb8 AA |
1917 | ri->next = utask->return_instances; |
1918 | utask->return_instances = ri; | |
1919 | ||
1920 | return; | |
0dfd0eb8 AA |
1921 | fail: |
1922 | kfree(ri); | |
1923 | } | |
1924 | ||
0326f5a9 SD |
1925 | /* Prepare to single-step probed instruction out of line. */ |
1926 | static int | |
a6cb3f6d | 1927 | pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long bp_vaddr) |
0326f5a9 | 1928 | { |
a6cb3f6d ON |
1929 | struct uprobe_task *utask; |
1930 | unsigned long xol_vaddr; | |
aba51024 | 1931 | int err; |
a6cb3f6d | 1932 | |
608e7427 ON |
1933 | utask = get_utask(); |
1934 | if (!utask) | |
1935 | return -ENOMEM; | |
a6cb3f6d ON |
1936 | |
1937 | xol_vaddr = xol_get_insn_slot(uprobe); | |
1938 | if (!xol_vaddr) | |
1939 | return -ENOMEM; | |
1940 | ||
1941 | utask->xol_vaddr = xol_vaddr; | |
1942 | utask->vaddr = bp_vaddr; | |
d4b3b638 | 1943 | |
aba51024 ON |
1944 | err = arch_uprobe_pre_xol(&uprobe->arch, regs); |
1945 | if (unlikely(err)) { | |
1946 | xol_free_insn_slot(current); | |
1947 | return err; | |
1948 | } | |
1949 | ||
608e7427 ON |
1950 | utask->active_uprobe = uprobe; |
1951 | utask->state = UTASK_SSTEP; | |
aba51024 | 1952 | return 0; |
0326f5a9 SD |
1953 | } |
1954 | ||
1955 | /* | |
1956 | * If we are singlestepping, then ensure this thread is not connected to | |
1957 | * non-fatal signals until completion of singlestep. When xol insn itself | |
1958 | * triggers the signal, restart the original insn even if the task is | |
1959 | * already SIGKILL'ed (since coredump should report the correct ip). This | |
1960 | * is even more important if the task has a handler for SIGSEGV/etc, The | |
1961 | * _same_ instruction should be repeated again after return from the signal | |
1962 | * handler, and SSTEP can never finish in this case. | |
1963 | */ | |
1964 | bool uprobe_deny_signal(void) | |
1965 | { | |
1966 | struct task_struct *t = current; | |
1967 | struct uprobe_task *utask = t->utask; | |
1968 | ||
1969 | if (likely(!utask || !utask->active_uprobe)) | |
1970 | return false; | |
1971 | ||
1972 | WARN_ON_ONCE(utask->state != UTASK_SSTEP); | |
1973 | ||
5c251e9d | 1974 | if (task_sigpending(t)) { |
0326f5a9 SD |
1975 | spin_lock_irq(&t->sighand->siglock); |
1976 | clear_tsk_thread_flag(t, TIF_SIGPENDING); | |
1977 | spin_unlock_irq(&t->sighand->siglock); | |
1978 | ||
1979 | if (__fatal_signal_pending(t) || arch_uprobe_xol_was_trapped(t)) { | |
1980 | utask->state = UTASK_SSTEP_TRAPPED; | |
1981 | set_tsk_thread_flag(t, TIF_UPROBE); | |
0326f5a9 SD |
1982 | } |
1983 | } | |
1984 | ||
1985 | return true; | |
1986 | } | |
1987 | ||
499a4f3e ON |
1988 | static void mmf_recalc_uprobes(struct mm_struct *mm) |
1989 | { | |
fcb72a58 | 1990 | VMA_ITERATOR(vmi, mm, 0); |
499a4f3e ON |
1991 | struct vm_area_struct *vma; |
1992 | ||
fcb72a58 | 1993 | for_each_vma(vmi, vma) { |
499a4f3e ON |
1994 | if (!valid_vma(vma, false)) |
1995 | continue; | |
1996 | /* | |
1997 | * This is not strictly accurate, we can race with | |
1998 | * uprobe_unregister() and see the already removed | |
1999 | * uprobe if delete_uprobe() was not yet called. | |
63633cbf | 2000 | * Or this uprobe can be filtered out. |
499a4f3e ON |
2001 | */ |
2002 | if (vma_has_uprobes(vma, vma->vm_start, vma->vm_end)) | |
2003 | return; | |
2004 | } | |
2005 | ||
2006 | clear_bit(MMF_HAS_UPROBES, &mm->flags); | |
2007 | } | |
2008 | ||
0908ad6e | 2009 | static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr) |
ec75fba9 ON |
2010 | { |
2011 | struct page *page; | |
2012 | uprobe_opcode_t opcode; | |
2013 | int result; | |
2014 | ||
013b2deb ON |
2015 | if (WARN_ON_ONCE(!IS_ALIGNED(vaddr, UPROBE_SWBP_INSN_SIZE))) |
2016 | return -EINVAL; | |
2017 | ||
ec75fba9 | 2018 | pagefault_disable(); |
bd28b145 | 2019 | result = __get_user(opcode, (uprobe_opcode_t __user *)vaddr); |
ec75fba9 ON |
2020 | pagefault_enable(); |
2021 | ||
2022 | if (likely(result == 0)) | |
2023 | goto out; | |
2024 | ||
1e987790 DH |
2025 | /* |
2026 | * The NULL 'tsk' here ensures that any faults that occur here | |
2027 | * will not be accounted to the task. 'mm' *is* current->mm, | |
2028 | * but we treat this as a 'remote' access since it is | |
2029 | * essentially a kernel access to the memory. | |
2030 | */ | |
64019a2e | 2031 | result = get_user_pages_remote(mm, vaddr, 1, FOLL_FORCE, &page, |
5b56d49f | 2032 | NULL, NULL); |
ec75fba9 ON |
2033 | if (result < 0) |
2034 | return result; | |
2035 | ||
ab0d805c | 2036 | copy_from_page(page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE); |
ec75fba9 ON |
2037 | put_page(page); |
2038 | out: | |
0908ad6e AM |
2039 | /* This needs to return true for any variant of the trap insn */ |
2040 | return is_trap_insn(&opcode); | |
ec75fba9 ON |
2041 | } |
2042 | ||
d790d346 | 2043 | static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp) |
0326f5a9 | 2044 | { |
3a9ea052 ON |
2045 | struct mm_struct *mm = current->mm; |
2046 | struct uprobe *uprobe = NULL; | |
0326f5a9 | 2047 | struct vm_area_struct *vma; |
0326f5a9 | 2048 | |
d8ed45c5 | 2049 | mmap_read_lock(mm); |
9016dded LH |
2050 | vma = vma_lookup(mm, bp_vaddr); |
2051 | if (vma) { | |
3a9ea052 | 2052 | if (valid_vma(vma, false)) { |
f281769e | 2053 | struct inode *inode = file_inode(vma->vm_file); |
cb113b47 | 2054 | loff_t offset = vaddr_to_offset(vma, bp_vaddr); |
0326f5a9 | 2055 | |
3a9ea052 ON |
2056 | uprobe = find_uprobe(inode, offset); |
2057 | } | |
d790d346 ON |
2058 | |
2059 | if (!uprobe) | |
0908ad6e | 2060 | *is_swbp = is_trap_at_addr(mm, bp_vaddr); |
d790d346 ON |
2061 | } else { |
2062 | *is_swbp = -EFAULT; | |
0326f5a9 | 2063 | } |
499a4f3e ON |
2064 | |
2065 | if (!uprobe && test_and_clear_bit(MMF_RECALC_UPROBES, &mm->flags)) | |
2066 | mmf_recalc_uprobes(mm); | |
d8ed45c5 | 2067 | mmap_read_unlock(mm); |
0326f5a9 | 2068 | |
3a9ea052 ON |
2069 | return uprobe; |
2070 | } | |
2071 | ||
da1816b1 ON |
2072 | static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs) |
2073 | { | |
2074 | struct uprobe_consumer *uc; | |
2075 | int remove = UPROBE_HANDLER_REMOVE; | |
0dfd0eb8 | 2076 | bool need_prep = false; /* prepare return uprobe, when needed */ |
da1816b1 ON |
2077 | |
2078 | down_read(&uprobe->register_rwsem); | |
2079 | for (uc = uprobe->consumers; uc; uc = uc->next) { | |
ea024870 | 2080 | int rc = 0; |
da1816b1 | 2081 | |
ea024870 AA |
2082 | if (uc->handler) { |
2083 | rc = uc->handler(uc, regs); | |
2084 | WARN(rc & ~UPROBE_HANDLER_MASK, | |
d75f773c | 2085 | "bad rc=0x%x from %ps()\n", rc, uc->handler); |
ea024870 | 2086 | } |
0dfd0eb8 AA |
2087 | |
2088 | if (uc->ret_handler) | |
2089 | need_prep = true; | |
2090 | ||
da1816b1 ON |
2091 | remove &= rc; |
2092 | } | |
2093 | ||
0dfd0eb8 AA |
2094 | if (need_prep && !remove) |
2095 | prepare_uretprobe(uprobe, regs); /* put bp at return */ | |
2096 | ||
da1816b1 ON |
2097 | if (remove && uprobe->consumers) { |
2098 | WARN_ON(!uprobe_is_active(uprobe)); | |
2099 | unapply_uprobe(uprobe, current->mm); | |
2100 | } | |
2101 | up_read(&uprobe->register_rwsem); | |
2102 | } | |
2103 | ||
fec8898d AA |
2104 | static void |
2105 | handle_uretprobe_chain(struct return_instance *ri, struct pt_regs *regs) | |
2106 | { | |
2107 | struct uprobe *uprobe = ri->uprobe; | |
2108 | struct uprobe_consumer *uc; | |
2109 | ||
2110 | down_read(&uprobe->register_rwsem); | |
2111 | for (uc = uprobe->consumers; uc; uc = uc->next) { | |
2112 | if (uc->ret_handler) | |
2113 | uc->ret_handler(uc, ri->func, regs); | |
2114 | } | |
2115 | up_read(&uprobe->register_rwsem); | |
2116 | } | |
2117 | ||
a83cfeb9 ON |
2118 | static struct return_instance *find_next_ret_chain(struct return_instance *ri) |
2119 | { | |
2120 | bool chained; | |
2121 | ||
2122 | do { | |
2123 | chained = ri->chained; | |
2124 | ri = ri->next; /* can't be NULL if chained */ | |
2125 | } while (chained); | |
2126 | ||
2127 | return ri; | |
2128 | } | |
2129 | ||
0b5256c7 | 2130 | static void handle_trampoline(struct pt_regs *regs) |
fec8898d AA |
2131 | { |
2132 | struct uprobe_task *utask; | |
a83cfeb9 | 2133 | struct return_instance *ri, *next; |
5eeb50de | 2134 | bool valid; |
fec8898d AA |
2135 | |
2136 | utask = current->utask; | |
2137 | if (!utask) | |
0b5256c7 | 2138 | goto sigill; |
fec8898d AA |
2139 | |
2140 | ri = utask->return_instances; | |
2141 | if (!ri) | |
0b5256c7 | 2142 | goto sigill; |
fec8898d | 2143 | |
a83cfeb9 | 2144 | do { |
5eeb50de ON |
2145 | /* |
2146 | * We should throw out the frames invalidated by longjmp(). | |
2147 | * If this chain is valid, then the next one should be alive | |
2148 | * or NULL; the latter case means that nobody but ri->func | |
2149 | * could hit this trampoline on return. TODO: sigaltstack(). | |
2150 | */ | |
2151 | next = find_next_ret_chain(ri); | |
86dcb702 | 2152 | valid = !next || arch_uretprobe_is_alive(next, RP_CHECK_RET, regs); |
5eeb50de ON |
2153 | |
2154 | instruction_pointer_set(regs, ri->orig_ret_vaddr); | |
2155 | do { | |
2156 | if (valid) | |
2157 | handle_uretprobe_chain(ri, regs); | |
2158 | ri = free_ret_instance(ri); | |
2159 | utask->depth--; | |
2160 | } while (ri != next); | |
2161 | } while (!valid); | |
fec8898d AA |
2162 | |
2163 | utask->return_instances = ri; | |
0b5256c7 ON |
2164 | return; |
2165 | ||
2166 | sigill: | |
2167 | uprobe_warn(current, "handle uretprobe, sending SIGILL."); | |
3cf5d076 | 2168 | force_sig(SIGILL); |
fec8898d | 2169 | |
fec8898d AA |
2170 | } |
2171 | ||
6fe50a28 DL |
2172 | bool __weak arch_uprobe_ignore(struct arch_uprobe *aup, struct pt_regs *regs) |
2173 | { | |
2174 | return false; | |
2175 | } | |
2176 | ||
86dcb702 ON |
2177 | bool __weak arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx, |
2178 | struct pt_regs *regs) | |
97da8976 ON |
2179 | { |
2180 | return true; | |
2181 | } | |
2182 | ||
3a9ea052 ON |
2183 | /* |
2184 | * Run handler and ask thread to singlestep. | |
2185 | * Ensure all non-fatal signals cannot interrupt thread while it singlesteps. | |
2186 | */ | |
2187 | static void handle_swbp(struct pt_regs *regs) | |
2188 | { | |
3a9ea052 ON |
2189 | struct uprobe *uprobe; |
2190 | unsigned long bp_vaddr; | |
3f649ab7 | 2191 | int is_swbp; |
3a9ea052 ON |
2192 | |
2193 | bp_vaddr = uprobe_get_swbp_addr(regs); | |
0b5256c7 ON |
2194 | if (bp_vaddr == get_trampoline_vaddr()) |
2195 | return handle_trampoline(regs); | |
fec8898d AA |
2196 | |
2197 | uprobe = find_active_uprobe(bp_vaddr, &is_swbp); | |
0326f5a9 | 2198 | if (!uprobe) { |
56bb4cf6 ON |
2199 | if (is_swbp > 0) { |
2200 | /* No matching uprobe; signal SIGTRAP. */ | |
fe5ed7ab | 2201 | force_sig(SIGTRAP); |
56bb4cf6 ON |
2202 | } else { |
2203 | /* | |
2204 | * Either we raced with uprobe_unregister() or we can't | |
2205 | * access this memory. The latter is only possible if | |
2206 | * another thread plays with our ->mm. In both cases | |
2207 | * we can simply restart. If this vma was unmapped we | |
2208 | * can pretend this insn was not executed yet and get | |
2209 | * the (correct) SIGSEGV after restart. | |
2210 | */ | |
2211 | instruction_pointer_set(regs, bp_vaddr); | |
2212 | } | |
0326f5a9 SD |
2213 | return; |
2214 | } | |
74e59dfc ON |
2215 | |
2216 | /* change it in advance for ->handler() and restart */ | |
2217 | instruction_pointer_set(regs, bp_vaddr); | |
2218 | ||
142b18dd ON |
2219 | /* |
2220 | * TODO: move copy_insn/etc into _register and remove this hack. | |
2221 | * After we hit the bp, _unregister + _register can install the | |
2222 | * new and not-yet-analyzed uprobe at the same address, restart. | |
2223 | */ | |
71434f2f | 2224 | if (unlikely(!test_bit(UPROBE_COPY_INSN, &uprobe->flags))) |
74e59dfc | 2225 | goto out; |
0326f5a9 | 2226 | |
09d3f015 AP |
2227 | /* |
2228 | * Pairs with the smp_wmb() in prepare_uprobe(). | |
2229 | * | |
2230 | * Guarantees that if we see the UPROBE_COPY_INSN bit set, then | |
2231 | * we must also see the stores to &uprobe->arch performed by the | |
2232 | * prepare_uprobe() call. | |
2233 | */ | |
2234 | smp_rmb(); | |
2235 | ||
72fd293a ON |
2236 | /* Tracing handlers use ->utask to communicate with fetch methods */ |
2237 | if (!get_utask()) | |
2238 | goto out; | |
2239 | ||
6fe50a28 DL |
2240 | if (arch_uprobe_ignore(&uprobe->arch, regs)) |
2241 | goto out; | |
2242 | ||
0326f5a9 | 2243 | handler_chain(uprobe, regs); |
6fe50a28 | 2244 | |
8a6b1732 | 2245 | if (arch_uprobe_skip_sstep(&uprobe->arch, regs)) |
0578a970 | 2246 | goto out; |
0326f5a9 | 2247 | |
608e7427 | 2248 | if (!pre_ssout(uprobe, regs, bp_vaddr)) |
0326f5a9 | 2249 | return; |
0326f5a9 | 2250 | |
8a6b1732 | 2251 | /* arch_uprobe_skip_sstep() succeeded, or restart if can't singlestep */ |
0578a970 | 2252 | out: |
8bd87445 | 2253 | put_uprobe(uprobe); |
0326f5a9 SD |
2254 | } |
2255 | ||
2256 | /* | |
2257 | * Perform required fix-ups and disable singlestep. | |
2258 | * Allow pending signals to take effect. | |
2259 | */ | |
2260 | static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs) | |
2261 | { | |
2262 | struct uprobe *uprobe; | |
014940ba | 2263 | int err = 0; |
0326f5a9 SD |
2264 | |
2265 | uprobe = utask->active_uprobe; | |
2266 | if (utask->state == UTASK_SSTEP_ACK) | |
014940ba | 2267 | err = arch_uprobe_post_xol(&uprobe->arch, regs); |
0326f5a9 SD |
2268 | else if (utask->state == UTASK_SSTEP_TRAPPED) |
2269 | arch_uprobe_abort_xol(&uprobe->arch, regs); | |
2270 | else | |
2271 | WARN_ON_ONCE(1); | |
2272 | ||
2273 | put_uprobe(uprobe); | |
2274 | utask->active_uprobe = NULL; | |
2275 | utask->state = UTASK_RUNNING; | |
d4b3b638 | 2276 | xol_free_insn_slot(current); |
0326f5a9 SD |
2277 | |
2278 | spin_lock_irq(¤t->sighand->siglock); | |
2279 | recalc_sigpending(); /* see uprobe_deny_signal() */ | |
2280 | spin_unlock_irq(¤t->sighand->siglock); | |
014940ba ON |
2281 | |
2282 | if (unlikely(err)) { | |
2283 | uprobe_warn(current, "execute the probed insn, sending SIGILL."); | |
3cf5d076 | 2284 | force_sig(SIGILL); |
014940ba | 2285 | } |
0326f5a9 SD |
2286 | } |
2287 | ||
2288 | /* | |
1b08e907 ON |
2289 | * On breakpoint hit, breakpoint notifier sets the TIF_UPROBE flag and |
2290 | * allows the thread to return from interrupt. After that handle_swbp() | |
2291 | * sets utask->active_uprobe. | |
0326f5a9 | 2292 | * |
1b08e907 ON |
2293 | * On singlestep exception, singlestep notifier sets the TIF_UPROBE flag |
2294 | * and allows the thread to return from interrupt. | |
0326f5a9 SD |
2295 | * |
2296 | * While returning to userspace, thread notices the TIF_UPROBE flag and calls | |
2297 | * uprobe_notify_resume(). | |
2298 | */ | |
2299 | void uprobe_notify_resume(struct pt_regs *regs) | |
2300 | { | |
2301 | struct uprobe_task *utask; | |
2302 | ||
db023ea5 ON |
2303 | clear_thread_flag(TIF_UPROBE); |
2304 | ||
0326f5a9 | 2305 | utask = current->utask; |
1b08e907 | 2306 | if (utask && utask->active_uprobe) |
0326f5a9 | 2307 | handle_singlestep(utask, regs); |
1b08e907 ON |
2308 | else |
2309 | handle_swbp(regs); | |
0326f5a9 SD |
2310 | } |
2311 | ||
2312 | /* | |
2313 | * uprobe_pre_sstep_notifier gets called from interrupt context as part of | |
2314 | * notifier mechanism. Set TIF_UPROBE flag and indicate breakpoint hit. | |
2315 | */ | |
2316 | int uprobe_pre_sstep_notifier(struct pt_regs *regs) | |
2317 | { | |
0dfd0eb8 AA |
2318 | if (!current->mm) |
2319 | return 0; | |
2320 | ||
2321 | if (!test_bit(MMF_HAS_UPROBES, ¤t->mm->flags) && | |
2322 | (!current->utask || !current->utask->return_instances)) | |
0326f5a9 SD |
2323 | return 0; |
2324 | ||
0326f5a9 | 2325 | set_thread_flag(TIF_UPROBE); |
0326f5a9 SD |
2326 | return 1; |
2327 | } | |
2328 | ||
2329 | /* | |
2330 | * uprobe_post_sstep_notifier gets called in interrupt context as part of notifier | |
2331 | * mechanism. Set TIF_UPROBE flag and indicate completion of singlestep. | |
2332 | */ | |
2333 | int uprobe_post_sstep_notifier(struct pt_regs *regs) | |
2334 | { | |
2335 | struct uprobe_task *utask = current->utask; | |
2336 | ||
2337 | if (!current->mm || !utask || !utask->active_uprobe) | |
2338 | /* task is currently not uprobed */ | |
2339 | return 0; | |
2340 | ||
2341 | utask->state = UTASK_SSTEP_ACK; | |
2342 | set_thread_flag(TIF_UPROBE); | |
2343 | return 1; | |
2344 | } | |
2345 | ||
2346 | static struct notifier_block uprobe_exception_nb = { | |
2347 | .notifier_call = arch_uprobe_exception_notify, | |
2348 | .priority = INT_MAX-1, /* notified after kprobes, kgdb */ | |
2349 | }; | |
2350 | ||
aad42dd4 | 2351 | void __init uprobes_init(void) |
2b144498 SD |
2352 | { |
2353 | int i; | |
2354 | ||
66d06dff | 2355 | for (i = 0; i < UPROBES_HASH_SZ; i++) |
2b144498 | 2356 | mutex_init(&uprobes_mmap_mutex[i]); |
0326f5a9 | 2357 | |
aad42dd4 | 2358 | BUG_ON(register_die_notifier(&uprobe_exception_nb)); |
2b144498 | 2359 | } |