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25763b3c | 1 | // SPDX-License-Identifier: GPL-2.0-only |
d5a3b1f6 | 2 | /* Copyright (c) 2016 Facebook |
d5a3b1f6 AS |
3 | */ |
4 | #include <linux/bpf.h> | |
5 | #include <linux/jhash.h> | |
6 | #include <linux/filter.h> | |
d5a3b1f6 AS |
7 | #include <linux/stacktrace.h> |
8 | #include <linux/perf_event.h> | |
615755a7 SL |
9 | #include <linux/elf.h> |
10 | #include <linux/pagemap.h> | |
bae77c5e | 11 | #include <linux/irq_work.h> |
557c0c6e | 12 | #include "percpu_freelist.h" |
d5a3b1f6 | 13 | |
615755a7 SL |
14 | #define STACK_CREATE_FLAG_MASK \ |
15 | (BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY | \ | |
16 | BPF_F_STACK_BUILD_ID) | |
6e71b04a | 17 | |
d5a3b1f6 | 18 | struct stack_map_bucket { |
557c0c6e | 19 | struct pcpu_freelist_node fnode; |
d5a3b1f6 AS |
20 | u32 hash; |
21 | u32 nr; | |
615755a7 | 22 | u64 data[]; |
d5a3b1f6 AS |
23 | }; |
24 | ||
25 | struct bpf_stack_map { | |
26 | struct bpf_map map; | |
557c0c6e AS |
27 | void *elems; |
28 | struct pcpu_freelist freelist; | |
d5a3b1f6 | 29 | u32 n_buckets; |
557c0c6e | 30 | struct stack_map_bucket *buckets[]; |
d5a3b1f6 AS |
31 | }; |
32 | ||
bae77c5e SL |
33 | /* irq_work to run up_read() for build_id lookup in nmi context */ |
34 | struct stack_map_irq_work { | |
35 | struct irq_work irq_work; | |
36 | struct rw_semaphore *sem; | |
37 | }; | |
38 | ||
39 | static void do_up_read(struct irq_work *entry) | |
40 | { | |
41 | struct stack_map_irq_work *work; | |
42 | ||
43 | work = container_of(entry, struct stack_map_irq_work, irq_work); | |
3defaf2f | 44 | up_read_non_owner(work->sem); |
bae77c5e SL |
45 | work->sem = NULL; |
46 | } | |
47 | ||
48 | static DEFINE_PER_CPU(struct stack_map_irq_work, up_read_work); | |
49 | ||
615755a7 SL |
50 | static inline bool stack_map_use_build_id(struct bpf_map *map) |
51 | { | |
52 | return (map->map_flags & BPF_F_STACK_BUILD_ID); | |
53 | } | |
54 | ||
55 | static inline int stack_map_data_size(struct bpf_map *map) | |
56 | { | |
57 | return stack_map_use_build_id(map) ? | |
58 | sizeof(struct bpf_stack_build_id) : sizeof(u64); | |
59 | } | |
60 | ||
557c0c6e AS |
61 | static int prealloc_elems_and_freelist(struct bpf_stack_map *smap) |
62 | { | |
63 | u32 elem_size = sizeof(struct stack_map_bucket) + smap->map.value_size; | |
64 | int err; | |
65 | ||
96eabe7a MKL |
66 | smap->elems = bpf_map_area_alloc(elem_size * smap->map.max_entries, |
67 | smap->map.numa_node); | |
557c0c6e AS |
68 | if (!smap->elems) |
69 | return -ENOMEM; | |
70 | ||
71 | err = pcpu_freelist_init(&smap->freelist); | |
72 | if (err) | |
73 | goto free_elems; | |
74 | ||
75 | pcpu_freelist_populate(&smap->freelist, smap->elems, elem_size, | |
76 | smap->map.max_entries); | |
77 | return 0; | |
78 | ||
79 | free_elems: | |
d407bd25 | 80 | bpf_map_area_free(smap->elems); |
557c0c6e AS |
81 | return err; |
82 | } | |
83 | ||
d5a3b1f6 AS |
84 | /* Called from syscall */ |
85 | static struct bpf_map *stack_map_alloc(union bpf_attr *attr) | |
86 | { | |
87 | u32 value_size = attr->value_size; | |
88 | struct bpf_stack_map *smap; | |
b936ca64 | 89 | struct bpf_map_memory mem; |
d5a3b1f6 AS |
90 | u64 cost, n_buckets; |
91 | int err; | |
92 | ||
93 | if (!capable(CAP_SYS_ADMIN)) | |
94 | return ERR_PTR(-EPERM); | |
95 | ||
6e71b04a | 96 | if (attr->map_flags & ~STACK_CREATE_FLAG_MASK) |
823707b6 AS |
97 | return ERR_PTR(-EINVAL); |
98 | ||
d5a3b1f6 AS |
99 | /* check sanity of attributes */ |
100 | if (attr->max_entries == 0 || attr->key_size != 4 || | |
615755a7 SL |
101 | value_size < 8 || value_size % 8) |
102 | return ERR_PTR(-EINVAL); | |
103 | ||
104 | BUILD_BUG_ON(sizeof(struct bpf_stack_build_id) % sizeof(u64)); | |
105 | if (attr->map_flags & BPF_F_STACK_BUILD_ID) { | |
106 | if (value_size % sizeof(struct bpf_stack_build_id) || | |
107 | value_size / sizeof(struct bpf_stack_build_id) | |
108 | > sysctl_perf_event_max_stack) | |
109 | return ERR_PTR(-EINVAL); | |
110 | } else if (value_size / 8 > sysctl_perf_event_max_stack) | |
d5a3b1f6 AS |
111 | return ERR_PTR(-EINVAL); |
112 | ||
113 | /* hash table size must be power of 2 */ | |
114 | n_buckets = roundup_pow_of_two(attr->max_entries); | |
115 | ||
116 | cost = n_buckets * sizeof(struct stack_map_bucket *) + sizeof(*smap); | |
b936ca64 | 117 | cost += n_buckets * (value_size + sizeof(struct stack_map_bucket)); |
c85d6913 | 118 | err = bpf_map_charge_init(&mem, cost); |
b936ca64 RG |
119 | if (err) |
120 | return ERR_PTR(err); | |
121 | ||
96eabe7a | 122 | smap = bpf_map_area_alloc(cost, bpf_map_attr_numa_node(attr)); |
b936ca64 RG |
123 | if (!smap) { |
124 | bpf_map_charge_finish(&mem); | |
d407bd25 | 125 | return ERR_PTR(-ENOMEM); |
b936ca64 | 126 | } |
d5a3b1f6 | 127 | |
bd475643 | 128 | bpf_map_init_from_attr(&smap->map, attr); |
d5a3b1f6 | 129 | smap->map.value_size = value_size; |
d5a3b1f6 | 130 | smap->n_buckets = n_buckets; |
557c0c6e | 131 | |
97c79a38 | 132 | err = get_callchain_buffers(sysctl_perf_event_max_stack); |
d5a3b1f6 | 133 | if (err) |
b936ca64 | 134 | goto free_charge; |
d5a3b1f6 | 135 | |
557c0c6e AS |
136 | err = prealloc_elems_and_freelist(smap); |
137 | if (err) | |
138 | goto put_buffers; | |
139 | ||
b936ca64 RG |
140 | bpf_map_charge_move(&smap->map.memory, &mem); |
141 | ||
d5a3b1f6 AS |
142 | return &smap->map; |
143 | ||
557c0c6e AS |
144 | put_buffers: |
145 | put_callchain_buffers(); | |
b936ca64 RG |
146 | free_charge: |
147 | bpf_map_charge_finish(&mem); | |
d407bd25 | 148 | bpf_map_area_free(smap); |
d5a3b1f6 AS |
149 | return ERR_PTR(err); |
150 | } | |
151 | ||
615755a7 SL |
152 | #define BPF_BUILD_ID 3 |
153 | /* | |
154 | * Parse build id from the note segment. This logic can be shared between | |
155 | * 32-bit and 64-bit system, because Elf32_Nhdr and Elf64_Nhdr are | |
156 | * identical. | |
157 | */ | |
158 | static inline int stack_map_parse_build_id(void *page_addr, | |
159 | unsigned char *build_id, | |
160 | void *note_start, | |
161 | Elf32_Word note_size) | |
162 | { | |
163 | Elf32_Word note_offs = 0, new_offs; | |
164 | ||
165 | /* check for overflow */ | |
166 | if (note_start < page_addr || note_start + note_size < note_start) | |
167 | return -EINVAL; | |
168 | ||
169 | /* only supports note that fits in the first page */ | |
170 | if (note_start + note_size > page_addr + PAGE_SIZE) | |
171 | return -EINVAL; | |
172 | ||
173 | while (note_offs + sizeof(Elf32_Nhdr) < note_size) { | |
174 | Elf32_Nhdr *nhdr = (Elf32_Nhdr *)(note_start + note_offs); | |
175 | ||
176 | if (nhdr->n_type == BPF_BUILD_ID && | |
177 | nhdr->n_namesz == sizeof("GNU") && | |
0b698005 SF |
178 | nhdr->n_descsz > 0 && |
179 | nhdr->n_descsz <= BPF_BUILD_ID_SIZE) { | |
615755a7 SL |
180 | memcpy(build_id, |
181 | note_start + note_offs + | |
182 | ALIGN(sizeof("GNU"), 4) + sizeof(Elf32_Nhdr), | |
0b698005 SF |
183 | nhdr->n_descsz); |
184 | memset(build_id + nhdr->n_descsz, 0, | |
185 | BPF_BUILD_ID_SIZE - nhdr->n_descsz); | |
615755a7 SL |
186 | return 0; |
187 | } | |
188 | new_offs = note_offs + sizeof(Elf32_Nhdr) + | |
189 | ALIGN(nhdr->n_namesz, 4) + ALIGN(nhdr->n_descsz, 4); | |
190 | if (new_offs <= note_offs) /* overflow */ | |
191 | break; | |
192 | note_offs = new_offs; | |
193 | } | |
194 | return -EINVAL; | |
195 | } | |
196 | ||
197 | /* Parse build ID from 32-bit ELF */ | |
198 | static int stack_map_get_build_id_32(void *page_addr, | |
199 | unsigned char *build_id) | |
200 | { | |
201 | Elf32_Ehdr *ehdr = (Elf32_Ehdr *)page_addr; | |
202 | Elf32_Phdr *phdr; | |
203 | int i; | |
204 | ||
205 | /* only supports phdr that fits in one page */ | |
206 | if (ehdr->e_phnum > | |
207 | (PAGE_SIZE - sizeof(Elf32_Ehdr)) / sizeof(Elf32_Phdr)) | |
208 | return -EINVAL; | |
209 | ||
210 | phdr = (Elf32_Phdr *)(page_addr + sizeof(Elf32_Ehdr)); | |
211 | ||
212 | for (i = 0; i < ehdr->e_phnum; ++i) | |
213 | if (phdr[i].p_type == PT_NOTE) | |
214 | return stack_map_parse_build_id(page_addr, build_id, | |
215 | page_addr + phdr[i].p_offset, | |
216 | phdr[i].p_filesz); | |
217 | return -EINVAL; | |
218 | } | |
219 | ||
220 | /* Parse build ID from 64-bit ELF */ | |
221 | static int stack_map_get_build_id_64(void *page_addr, | |
222 | unsigned char *build_id) | |
223 | { | |
224 | Elf64_Ehdr *ehdr = (Elf64_Ehdr *)page_addr; | |
225 | Elf64_Phdr *phdr; | |
226 | int i; | |
227 | ||
228 | /* only supports phdr that fits in one page */ | |
229 | if (ehdr->e_phnum > | |
230 | (PAGE_SIZE - sizeof(Elf64_Ehdr)) / sizeof(Elf64_Phdr)) | |
231 | return -EINVAL; | |
232 | ||
233 | phdr = (Elf64_Phdr *)(page_addr + sizeof(Elf64_Ehdr)); | |
234 | ||
235 | for (i = 0; i < ehdr->e_phnum; ++i) | |
236 | if (phdr[i].p_type == PT_NOTE) | |
237 | return stack_map_parse_build_id(page_addr, build_id, | |
238 | page_addr + phdr[i].p_offset, | |
239 | phdr[i].p_filesz); | |
240 | return -EINVAL; | |
241 | } | |
242 | ||
243 | /* Parse build ID of ELF file mapped to vma */ | |
244 | static int stack_map_get_build_id(struct vm_area_struct *vma, | |
245 | unsigned char *build_id) | |
246 | { | |
247 | Elf32_Ehdr *ehdr; | |
248 | struct page *page; | |
249 | void *page_addr; | |
250 | int ret; | |
251 | ||
252 | /* only works for page backed storage */ | |
253 | if (!vma->vm_file) | |
254 | return -EINVAL; | |
255 | ||
256 | page = find_get_page(vma->vm_file->f_mapping, 0); | |
257 | if (!page) | |
258 | return -EFAULT; /* page not mapped */ | |
259 | ||
260 | ret = -EINVAL; | |
beaf3d19 | 261 | page_addr = kmap_atomic(page); |
615755a7 SL |
262 | ehdr = (Elf32_Ehdr *)page_addr; |
263 | ||
264 | /* compare magic x7f "ELF" */ | |
265 | if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0) | |
266 | goto out; | |
267 | ||
268 | /* only support executable file and shared object file */ | |
269 | if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN) | |
270 | goto out; | |
271 | ||
272 | if (ehdr->e_ident[EI_CLASS] == ELFCLASS32) | |
273 | ret = stack_map_get_build_id_32(page_addr, build_id); | |
274 | else if (ehdr->e_ident[EI_CLASS] == ELFCLASS64) | |
275 | ret = stack_map_get_build_id_64(page_addr, build_id); | |
276 | out: | |
beaf3d19 | 277 | kunmap_atomic(page_addr); |
615755a7 SL |
278 | put_page(page); |
279 | return ret; | |
280 | } | |
281 | ||
5f412632 | 282 | static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs, |
615755a7 SL |
283 | u64 *ips, u32 trace_nr, bool user) |
284 | { | |
285 | int i; | |
286 | struct vm_area_struct *vma; | |
bae77c5e | 287 | bool irq_work_busy = false; |
dc3b8ae9 | 288 | struct stack_map_irq_work *work = NULL; |
bae77c5e | 289 | |
eac9153f | 290 | if (irqs_disabled()) { |
bae77c5e | 291 | work = this_cpu_ptr(&up_read_work); |
153bedba | 292 | if (atomic_read(&work->irq_work.flags) & IRQ_WORK_BUSY) |
bae77c5e SL |
293 | /* cannot queue more up_read, fallback */ |
294 | irq_work_busy = true; | |
295 | } | |
615755a7 SL |
296 | |
297 | /* | |
eac9153f SL |
298 | * We cannot do up_read() when the irq is disabled, because of |
299 | * risk to deadlock with rq_lock. To do build_id lookup when the | |
300 | * irqs are disabled, we need to run up_read() in irq_work. We use | |
bae77c5e SL |
301 | * a percpu variable to do the irq_work. If the irq_work is |
302 | * already used by another lookup, we fall back to report ips. | |
615755a7 SL |
303 | * |
304 | * Same fallback is used for kernel stack (!user) on a stackmap | |
305 | * with build_id. | |
306 | */ | |
bae77c5e | 307 | if (!user || !current || !current->mm || irq_work_busy || |
615755a7 SL |
308 | down_read_trylock(¤t->mm->mmap_sem) == 0) { |
309 | /* cannot access current->mm, fall back to ips */ | |
310 | for (i = 0; i < trace_nr; i++) { | |
311 | id_offs[i].status = BPF_STACK_BUILD_ID_IP; | |
312 | id_offs[i].ip = ips[i]; | |
4af396ae | 313 | memset(id_offs[i].build_id, 0, BPF_BUILD_ID_SIZE); |
615755a7 SL |
314 | } |
315 | return; | |
316 | } | |
317 | ||
318 | for (i = 0; i < trace_nr; i++) { | |
319 | vma = find_vma(current->mm, ips[i]); | |
320 | if (!vma || stack_map_get_build_id(vma, id_offs[i].build_id)) { | |
321 | /* per entry fall back to ips */ | |
322 | id_offs[i].status = BPF_STACK_BUILD_ID_IP; | |
323 | id_offs[i].ip = ips[i]; | |
4af396ae | 324 | memset(id_offs[i].build_id, 0, BPF_BUILD_ID_SIZE); |
615755a7 SL |
325 | continue; |
326 | } | |
327 | id_offs[i].offset = (vma->vm_pgoff << PAGE_SHIFT) + ips[i] | |
328 | - vma->vm_start; | |
329 | id_offs[i].status = BPF_STACK_BUILD_ID_VALID; | |
330 | } | |
bae77c5e | 331 | |
dc3b8ae9 | 332 | if (!work) { |
bae77c5e SL |
333 | up_read(¤t->mm->mmap_sem); |
334 | } else { | |
335 | work->sem = ¤t->mm->mmap_sem; | |
336 | irq_work_queue(&work->irq_work); | |
3defaf2f AS |
337 | /* |
338 | * The irq_work will release the mmap_sem with | |
339 | * up_read_non_owner(). The rwsem_release() is called | |
340 | * here to release the lock from lockdep's perspective. | |
341 | */ | |
5facae4f | 342 | rwsem_release(¤t->mm->mmap_sem.dep_map, _RET_IP_); |
bae77c5e | 343 | } |
615755a7 SL |
344 | } |
345 | ||
f3694e00 DB |
346 | BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map, |
347 | u64, flags) | |
d5a3b1f6 | 348 | { |
d5a3b1f6 AS |
349 | struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); |
350 | struct perf_callchain_entry *trace; | |
351 | struct stack_map_bucket *bucket, *new_bucket, *old_bucket; | |
615755a7 | 352 | u32 max_depth = map->value_size / stack_map_data_size(map); |
c5dfd78e ACM |
353 | /* stack_map_alloc() checks that max_depth <= sysctl_perf_event_max_stack */ |
354 | u32 init_nr = sysctl_perf_event_max_stack - max_depth; | |
d5a3b1f6 AS |
355 | u32 skip = flags & BPF_F_SKIP_FIELD_MASK; |
356 | u32 hash, id, trace_nr, trace_len; | |
357 | bool user = flags & BPF_F_USER_STACK; | |
358 | bool kernel = !user; | |
359 | u64 *ips; | |
615755a7 | 360 | bool hash_matches; |
d5a3b1f6 AS |
361 | |
362 | if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | | |
363 | BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID))) | |
364 | return -EINVAL; | |
365 | ||
cfbcf468 ACM |
366 | trace = get_perf_callchain(regs, init_nr, kernel, user, |
367 | sysctl_perf_event_max_stack, false, false); | |
d5a3b1f6 AS |
368 | |
369 | if (unlikely(!trace)) | |
370 | /* couldn't fetch the stack trace */ | |
371 | return -EFAULT; | |
372 | ||
373 | /* get_perf_callchain() guarantees that trace->nr >= init_nr | |
c5dfd78e | 374 | * and trace-nr <= sysctl_perf_event_max_stack, so trace_nr <= max_depth |
d5a3b1f6 AS |
375 | */ |
376 | trace_nr = trace->nr - init_nr; | |
377 | ||
378 | if (trace_nr <= skip) | |
379 | /* skipping more than usable stack trace */ | |
380 | return -EFAULT; | |
381 | ||
382 | trace_nr -= skip; | |
383 | trace_len = trace_nr * sizeof(u64); | |
384 | ips = trace->ip + skip + init_nr; | |
385 | hash = jhash2((u32 *)ips, trace_len / sizeof(u32), 0); | |
386 | id = hash & (smap->n_buckets - 1); | |
557c0c6e | 387 | bucket = READ_ONCE(smap->buckets[id]); |
d5a3b1f6 | 388 | |
615755a7 SL |
389 | hash_matches = bucket && bucket->hash == hash; |
390 | /* fast cmp */ | |
391 | if (hash_matches && flags & BPF_F_FAST_STACK_CMP) | |
392 | return id; | |
393 | ||
394 | if (stack_map_use_build_id(map)) { | |
395 | /* for build_id+offset, pop a bucket before slow cmp */ | |
396 | new_bucket = (struct stack_map_bucket *) | |
397 | pcpu_freelist_pop(&smap->freelist); | |
398 | if (unlikely(!new_bucket)) | |
399 | return -ENOMEM; | |
5f412632 YS |
400 | new_bucket->nr = trace_nr; |
401 | stack_map_get_build_id_offset( | |
402 | (struct bpf_stack_build_id *)new_bucket->data, | |
403 | ips, trace_nr, user); | |
615755a7 SL |
404 | trace_len = trace_nr * sizeof(struct bpf_stack_build_id); |
405 | if (hash_matches && bucket->nr == trace_nr && | |
406 | memcmp(bucket->data, new_bucket->data, trace_len) == 0) { | |
407 | pcpu_freelist_push(&smap->freelist, &new_bucket->fnode); | |
d5a3b1f6 | 408 | return id; |
615755a7 SL |
409 | } |
410 | if (bucket && !(flags & BPF_F_REUSE_STACKID)) { | |
411 | pcpu_freelist_push(&smap->freelist, &new_bucket->fnode); | |
412 | return -EEXIST; | |
413 | } | |
414 | } else { | |
415 | if (hash_matches && bucket->nr == trace_nr && | |
416 | memcmp(bucket->data, ips, trace_len) == 0) | |
d5a3b1f6 | 417 | return id; |
615755a7 SL |
418 | if (bucket && !(flags & BPF_F_REUSE_STACKID)) |
419 | return -EEXIST; | |
420 | ||
421 | new_bucket = (struct stack_map_bucket *) | |
422 | pcpu_freelist_pop(&smap->freelist); | |
423 | if (unlikely(!new_bucket)) | |
424 | return -ENOMEM; | |
425 | memcpy(new_bucket->data, ips, trace_len); | |
d5a3b1f6 AS |
426 | } |
427 | ||
d5a3b1f6 AS |
428 | new_bucket->hash = hash; |
429 | new_bucket->nr = trace_nr; | |
430 | ||
431 | old_bucket = xchg(&smap->buckets[id], new_bucket); | |
432 | if (old_bucket) | |
557c0c6e | 433 | pcpu_freelist_push(&smap->freelist, &old_bucket->fnode); |
d5a3b1f6 AS |
434 | return id; |
435 | } | |
436 | ||
437 | const struct bpf_func_proto bpf_get_stackid_proto = { | |
438 | .func = bpf_get_stackid, | |
439 | .gpl_only = true, | |
440 | .ret_type = RET_INTEGER, | |
441 | .arg1_type = ARG_PTR_TO_CTX, | |
442 | .arg2_type = ARG_CONST_MAP_PTR, | |
443 | .arg3_type = ARG_ANYTHING, | |
444 | }; | |
445 | ||
c195651e YS |
446 | BPF_CALL_4(bpf_get_stack, struct pt_regs *, regs, void *, buf, u32, size, |
447 | u64, flags) | |
448 | { | |
449 | u32 init_nr, trace_nr, copy_len, elem_size, num_elem; | |
450 | bool user_build_id = flags & BPF_F_USER_BUILD_ID; | |
451 | u32 skip = flags & BPF_F_SKIP_FIELD_MASK; | |
452 | bool user = flags & BPF_F_USER_STACK; | |
453 | struct perf_callchain_entry *trace; | |
454 | bool kernel = !user; | |
455 | int err = -EINVAL; | |
456 | u64 *ips; | |
457 | ||
458 | if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | | |
459 | BPF_F_USER_BUILD_ID))) | |
460 | goto clear; | |
461 | if (kernel && user_build_id) | |
462 | goto clear; | |
463 | ||
464 | elem_size = (user && user_build_id) ? sizeof(struct bpf_stack_build_id) | |
465 | : sizeof(u64); | |
466 | if (unlikely(size % elem_size)) | |
467 | goto clear; | |
468 | ||
469 | num_elem = size / elem_size; | |
470 | if (sysctl_perf_event_max_stack < num_elem) | |
471 | init_nr = 0; | |
472 | else | |
473 | init_nr = sysctl_perf_event_max_stack - num_elem; | |
474 | trace = get_perf_callchain(regs, init_nr, kernel, user, | |
475 | sysctl_perf_event_max_stack, false, false); | |
476 | if (unlikely(!trace)) | |
477 | goto err_fault; | |
478 | ||
479 | trace_nr = trace->nr - init_nr; | |
480 | if (trace_nr < skip) | |
481 | goto err_fault; | |
482 | ||
483 | trace_nr -= skip; | |
484 | trace_nr = (trace_nr <= num_elem) ? trace_nr : num_elem; | |
485 | copy_len = trace_nr * elem_size; | |
486 | ips = trace->ip + skip + init_nr; | |
487 | if (user && user_build_id) | |
488 | stack_map_get_build_id_offset(buf, ips, trace_nr, user); | |
489 | else | |
490 | memcpy(buf, ips, copy_len); | |
491 | ||
492 | if (size > copy_len) | |
493 | memset(buf + copy_len, 0, size - copy_len); | |
494 | return copy_len; | |
495 | ||
496 | err_fault: | |
497 | err = -EFAULT; | |
498 | clear: | |
499 | memset(buf, 0, size); | |
500 | return err; | |
501 | } | |
502 | ||
503 | const struct bpf_func_proto bpf_get_stack_proto = { | |
504 | .func = bpf_get_stack, | |
505 | .gpl_only = true, | |
506 | .ret_type = RET_INTEGER, | |
507 | .arg1_type = ARG_PTR_TO_CTX, | |
508 | .arg2_type = ARG_PTR_TO_UNINIT_MEM, | |
509 | .arg3_type = ARG_CONST_SIZE_OR_ZERO, | |
510 | .arg4_type = ARG_ANYTHING, | |
511 | }; | |
512 | ||
557c0c6e | 513 | /* Called from eBPF program */ |
d5a3b1f6 | 514 | static void *stack_map_lookup_elem(struct bpf_map *map, void *key) |
557c0c6e | 515 | { |
3b4a63f6 | 516 | return ERR_PTR(-EOPNOTSUPP); |
557c0c6e AS |
517 | } |
518 | ||
519 | /* Called from syscall */ | |
520 | int bpf_stackmap_copy(struct bpf_map *map, void *key, void *value) | |
d5a3b1f6 AS |
521 | { |
522 | struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); | |
557c0c6e AS |
523 | struct stack_map_bucket *bucket, *old_bucket; |
524 | u32 id = *(u32 *)key, trace_len; | |
d5a3b1f6 AS |
525 | |
526 | if (unlikely(id >= smap->n_buckets)) | |
557c0c6e AS |
527 | return -ENOENT; |
528 | ||
529 | bucket = xchg(&smap->buckets[id], NULL); | |
530 | if (!bucket) | |
531 | return -ENOENT; | |
532 | ||
615755a7 SL |
533 | trace_len = bucket->nr * stack_map_data_size(map); |
534 | memcpy(value, bucket->data, trace_len); | |
557c0c6e AS |
535 | memset(value + trace_len, 0, map->value_size - trace_len); |
536 | ||
537 | old_bucket = xchg(&smap->buckets[id], bucket); | |
538 | if (old_bucket) | |
539 | pcpu_freelist_push(&smap->freelist, &old_bucket->fnode); | |
540 | return 0; | |
d5a3b1f6 AS |
541 | } |
542 | ||
16f07c55 YS |
543 | static int stack_map_get_next_key(struct bpf_map *map, void *key, |
544 | void *next_key) | |
d5a3b1f6 | 545 | { |
16f07c55 YS |
546 | struct bpf_stack_map *smap = container_of(map, |
547 | struct bpf_stack_map, map); | |
548 | u32 id; | |
549 | ||
550 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
551 | ||
552 | if (!key) { | |
553 | id = 0; | |
554 | } else { | |
555 | id = *(u32 *)key; | |
556 | if (id >= smap->n_buckets || !smap->buckets[id]) | |
557 | id = 0; | |
558 | else | |
559 | id++; | |
560 | } | |
561 | ||
562 | while (id < smap->n_buckets && !smap->buckets[id]) | |
563 | id++; | |
564 | ||
565 | if (id >= smap->n_buckets) | |
566 | return -ENOENT; | |
567 | ||
568 | *(u32 *)next_key = id; | |
569 | return 0; | |
d5a3b1f6 AS |
570 | } |
571 | ||
572 | static int stack_map_update_elem(struct bpf_map *map, void *key, void *value, | |
573 | u64 map_flags) | |
574 | { | |
575 | return -EINVAL; | |
576 | } | |
577 | ||
578 | /* Called from syscall or from eBPF program */ | |
579 | static int stack_map_delete_elem(struct bpf_map *map, void *key) | |
580 | { | |
581 | struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); | |
582 | struct stack_map_bucket *old_bucket; | |
583 | u32 id = *(u32 *)key; | |
584 | ||
585 | if (unlikely(id >= smap->n_buckets)) | |
586 | return -E2BIG; | |
587 | ||
588 | old_bucket = xchg(&smap->buckets[id], NULL); | |
589 | if (old_bucket) { | |
557c0c6e | 590 | pcpu_freelist_push(&smap->freelist, &old_bucket->fnode); |
d5a3b1f6 AS |
591 | return 0; |
592 | } else { | |
593 | return -ENOENT; | |
594 | } | |
595 | } | |
596 | ||
597 | /* Called when map->refcnt goes to zero, either from workqueue or from syscall */ | |
598 | static void stack_map_free(struct bpf_map *map) | |
599 | { | |
600 | struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); | |
d5a3b1f6 | 601 | |
557c0c6e | 602 | /* wait for bpf programs to complete before freeing stack map */ |
d5a3b1f6 AS |
603 | synchronize_rcu(); |
604 | ||
d407bd25 | 605 | bpf_map_area_free(smap->elems); |
557c0c6e | 606 | pcpu_freelist_destroy(&smap->freelist); |
d407bd25 | 607 | bpf_map_area_free(smap); |
d5a3b1f6 AS |
608 | put_callchain_buffers(); |
609 | } | |
610 | ||
14499160 | 611 | const struct bpf_map_ops stack_trace_map_ops = { |
d5a3b1f6 AS |
612 | .map_alloc = stack_map_alloc, |
613 | .map_free = stack_map_free, | |
614 | .map_get_next_key = stack_map_get_next_key, | |
615 | .map_lookup_elem = stack_map_lookup_elem, | |
616 | .map_update_elem = stack_map_update_elem, | |
617 | .map_delete_elem = stack_map_delete_elem, | |
e8d2bec0 | 618 | .map_check_btf = map_check_no_btf, |
d5a3b1f6 | 619 | }; |
bae77c5e SL |
620 | |
621 | static int __init stack_map_init(void) | |
622 | { | |
623 | int cpu; | |
624 | struct stack_map_irq_work *work; | |
625 | ||
626 | for_each_possible_cpu(cpu) { | |
627 | work = per_cpu_ptr(&up_read_work, cpu); | |
628 | init_irq_work(&work->irq_work, do_up_read); | |
629 | } | |
630 | return 0; | |
631 | } | |
632 | subsys_initcall(stack_map_init); |