1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* Copyright (c) 2016 Facebook |
3 | */ |
4 | #include <linux/bpf.h> |
5 | #include <linux/jhash.h> |
6 | #include <linux/filter.h> |
7 | #include <linux/kernel.h> |
8 | #include <linux/stacktrace.h> |
9 | #include <linux/perf_event.h> |
10 | #include <linux/btf_ids.h> |
11 | #include <linux/buildid.h> |
12 | #include "percpu_freelist.h" |
13 | #include "mmap_unlock_work.h" |
14 | |
15 | #define STACK_CREATE_FLAG_MASK \ |
16 | (BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY | \ |
17 | BPF_F_STACK_BUILD_ID) |
18 | |
19 | struct stack_map_bucket { |
20 | struct pcpu_freelist_node fnode; |
21 | u32 hash; |
22 | u32 nr; |
23 | u64 data[]; |
24 | }; |
25 | |
26 | struct bpf_stack_map { |
27 | struct bpf_map map; |
28 | void *elems; |
29 | struct pcpu_freelist freelist; |
30 | u32 n_buckets; |
31 | struct stack_map_bucket *buckets[] __counted_by(n_buckets); |
32 | }; |
33 | |
34 | static inline bool stack_map_use_build_id(struct bpf_map *map) |
35 | { |
36 | return (map->map_flags & BPF_F_STACK_BUILD_ID); |
37 | } |
38 | |
39 | static inline int stack_map_data_size(struct bpf_map *map) |
40 | { |
41 | return stack_map_use_build_id(map) ? |
42 | sizeof(struct bpf_stack_build_id) : sizeof(u64); |
43 | } |
44 | |
45 | static int prealloc_elems_and_freelist(struct bpf_stack_map *smap) |
46 | { |
47 | u64 elem_size = sizeof(struct stack_map_bucket) + |
48 | (u64)smap->map.value_size; |
49 | int err; |
50 | |
51 | smap->elems = bpf_map_area_alloc(size: elem_size * smap->map.max_entries, |
52 | numa_node: smap->map.numa_node); |
53 | if (!smap->elems) |
54 | return -ENOMEM; |
55 | |
56 | err = pcpu_freelist_init(&smap->freelist); |
57 | if (err) |
58 | goto free_elems; |
59 | |
60 | pcpu_freelist_populate(s: &smap->freelist, buf: smap->elems, elem_size, |
61 | nr_elems: smap->map.max_entries); |
62 | return 0; |
63 | |
64 | free_elems: |
65 | bpf_map_area_free(base: smap->elems); |
66 | return err; |
67 | } |
68 | |
69 | /* Called from syscall */ |
70 | static struct bpf_map *stack_map_alloc(union bpf_attr *attr) |
71 | { |
72 | u32 value_size = attr->value_size; |
73 | struct bpf_stack_map *smap; |
74 | u64 cost, n_buckets; |
75 | int err; |
76 | |
77 | if (attr->map_flags & ~STACK_CREATE_FLAG_MASK) |
78 | return ERR_PTR(error: -EINVAL); |
79 | |
80 | /* check sanity of attributes */ |
81 | if (attr->max_entries == 0 || attr->key_size != 4 || |
82 | value_size < 8 || value_size % 8) |
83 | return ERR_PTR(error: -EINVAL); |
84 | |
85 | BUILD_BUG_ON(sizeof(struct bpf_stack_build_id) % sizeof(u64)); |
86 | if (attr->map_flags & BPF_F_STACK_BUILD_ID) { |
87 | if (value_size % sizeof(struct bpf_stack_build_id) || |
88 | value_size / sizeof(struct bpf_stack_build_id) |
89 | > sysctl_perf_event_max_stack) |
90 | return ERR_PTR(error: -EINVAL); |
91 | } else if (value_size / 8 > sysctl_perf_event_max_stack) |
92 | return ERR_PTR(error: -EINVAL); |
93 | |
94 | /* hash table size must be power of 2; roundup_pow_of_two() can overflow |
95 | * into UB on 32-bit arches, so check that first |
96 | */ |
97 | if (attr->max_entries > 1UL << 31) |
98 | return ERR_PTR(error: -E2BIG); |
99 | |
100 | n_buckets = roundup_pow_of_two(attr->max_entries); |
101 | |
102 | cost = n_buckets * sizeof(struct stack_map_bucket *) + sizeof(*smap); |
103 | smap = bpf_map_area_alloc(size: cost, numa_node: bpf_map_attr_numa_node(attr)); |
104 | if (!smap) |
105 | return ERR_PTR(error: -ENOMEM); |
106 | |
107 | bpf_map_init_from_attr(map: &smap->map, attr); |
108 | smap->n_buckets = n_buckets; |
109 | |
110 | err = get_callchain_buffers(max_stack: sysctl_perf_event_max_stack); |
111 | if (err) |
112 | goto free_smap; |
113 | |
114 | err = prealloc_elems_and_freelist(smap); |
115 | if (err) |
116 | goto put_buffers; |
117 | |
118 | return &smap->map; |
119 | |
120 | put_buffers: |
121 | put_callchain_buffers(); |
122 | free_smap: |
123 | bpf_map_area_free(base: smap); |
124 | return ERR_PTR(error: err); |
125 | } |
126 | |
127 | static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs, |
128 | u64 *ips, u32 trace_nr, bool user) |
129 | { |
130 | int i; |
131 | struct mmap_unlock_irq_work *work = NULL; |
132 | bool irq_work_busy = bpf_mmap_unlock_get_irq_work(work_ptr: &work); |
133 | struct vm_area_struct *vma, *prev_vma = NULL; |
134 | const char *prev_build_id; |
135 | |
136 | /* If the irq_work is in use, fall back to report ips. Same |
137 | * fallback is used for kernel stack (!user) on a stackmap with |
138 | * build_id. |
139 | */ |
140 | if (!user || !current || !current->mm || irq_work_busy || |
141 | !mmap_read_trylock(current->mm)) { |
142 | /* cannot access current->mm, fall back to ips */ |
143 | for (i = 0; i < trace_nr; i++) { |
144 | id_offs[i].status = BPF_STACK_BUILD_ID_IP; |
145 | id_offs[i].ip = ips[i]; |
146 | memset(id_offs[i].build_id, 0, BUILD_ID_SIZE_MAX); |
147 | } |
148 | return; |
149 | } |
150 | |
151 | for (i = 0; i < trace_nr; i++) { |
152 | if (range_in_vma(vma: prev_vma, start: ips[i], end: ips[i])) { |
153 | vma = prev_vma; |
154 | memcpy(id_offs[i].build_id, prev_build_id, |
155 | BUILD_ID_SIZE_MAX); |
156 | goto build_id_valid; |
157 | } |
158 | vma = find_vma(current->mm, addr: ips[i]); |
159 | if (!vma || build_id_parse(vma, build_id: id_offs[i].build_id, NULL)) { |
160 | /* per entry fall back to ips */ |
161 | id_offs[i].status = BPF_STACK_BUILD_ID_IP; |
162 | id_offs[i].ip = ips[i]; |
163 | memset(id_offs[i].build_id, 0, BUILD_ID_SIZE_MAX); |
164 | continue; |
165 | } |
166 | build_id_valid: |
167 | id_offs[i].offset = (vma->vm_pgoff << PAGE_SHIFT) + ips[i] |
168 | - vma->vm_start; |
169 | id_offs[i].status = BPF_STACK_BUILD_ID_VALID; |
170 | prev_vma = vma; |
171 | prev_build_id = id_offs[i].build_id; |
172 | } |
173 | bpf_mmap_unlock_mm(work, current->mm); |
174 | } |
175 | |
176 | static struct perf_callchain_entry * |
177 | get_callchain_entry_for_task(struct task_struct *task, u32 max_depth) |
178 | { |
179 | #ifdef CONFIG_STACKTRACE |
180 | struct perf_callchain_entry *entry; |
181 | int rctx; |
182 | |
183 | entry = get_callchain_entry(rctx: &rctx); |
184 | |
185 | if (!entry) |
186 | return NULL; |
187 | |
188 | entry->nr = stack_trace_save_tsk(task, store: (unsigned long *)entry->ip, |
189 | size: max_depth, skipnr: 0); |
190 | |
191 | /* stack_trace_save_tsk() works on unsigned long array, while |
192 | * perf_callchain_entry uses u64 array. For 32-bit systems, it is |
193 | * necessary to fix this mismatch. |
194 | */ |
195 | if (__BITS_PER_LONG != 64) { |
196 | unsigned long *from = (unsigned long *) entry->ip; |
197 | u64 *to = entry->ip; |
198 | int i; |
199 | |
200 | /* copy data from the end to avoid using extra buffer */ |
201 | for (i = entry->nr - 1; i >= 0; i--) |
202 | to[i] = (u64)(from[i]); |
203 | } |
204 | |
205 | put_callchain_entry(rctx); |
206 | |
207 | return entry; |
208 | #else /* CONFIG_STACKTRACE */ |
209 | return NULL; |
210 | #endif |
211 | } |
212 | |
213 | static long __bpf_get_stackid(struct bpf_map *map, |
214 | struct perf_callchain_entry *trace, u64 flags) |
215 | { |
216 | struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); |
217 | struct stack_map_bucket *bucket, *new_bucket, *old_bucket; |
218 | u32 skip = flags & BPF_F_SKIP_FIELD_MASK; |
219 | u32 hash, id, trace_nr, trace_len; |
220 | bool user = flags & BPF_F_USER_STACK; |
221 | u64 *ips; |
222 | bool hash_matches; |
223 | |
224 | if (trace->nr <= skip) |
225 | /* skipping more than usable stack trace */ |
226 | return -EFAULT; |
227 | |
228 | trace_nr = trace->nr - skip; |
229 | trace_len = trace_nr * sizeof(u64); |
230 | ips = trace->ip + skip; |
231 | hash = jhash2(k: (u32 *)ips, length: trace_len / sizeof(u32), initval: 0); |
232 | id = hash & (smap->n_buckets - 1); |
233 | bucket = READ_ONCE(smap->buckets[id]); |
234 | |
235 | hash_matches = bucket && bucket->hash == hash; |
236 | /* fast cmp */ |
237 | if (hash_matches && flags & BPF_F_FAST_STACK_CMP) |
238 | return id; |
239 | |
240 | if (stack_map_use_build_id(map)) { |
241 | /* for build_id+offset, pop a bucket before slow cmp */ |
242 | new_bucket = (struct stack_map_bucket *) |
243 | pcpu_freelist_pop(&smap->freelist); |
244 | if (unlikely(!new_bucket)) |
245 | return -ENOMEM; |
246 | new_bucket->nr = trace_nr; |
247 | stack_map_get_build_id_offset( |
248 | id_offs: (struct bpf_stack_build_id *)new_bucket->data, |
249 | ips, trace_nr, user); |
250 | trace_len = trace_nr * sizeof(struct bpf_stack_build_id); |
251 | if (hash_matches && bucket->nr == trace_nr && |
252 | memcmp(p: bucket->data, q: new_bucket->data, size: trace_len) == 0) { |
253 | pcpu_freelist_push(&smap->freelist, &new_bucket->fnode); |
254 | return id; |
255 | } |
256 | if (bucket && !(flags & BPF_F_REUSE_STACKID)) { |
257 | pcpu_freelist_push(&smap->freelist, &new_bucket->fnode); |
258 | return -EEXIST; |
259 | } |
260 | } else { |
261 | if (hash_matches && bucket->nr == trace_nr && |
262 | memcmp(p: bucket->data, q: ips, size: trace_len) == 0) |
263 | return id; |
264 | if (bucket && !(flags & BPF_F_REUSE_STACKID)) |
265 | return -EEXIST; |
266 | |
267 | new_bucket = (struct stack_map_bucket *) |
268 | pcpu_freelist_pop(&smap->freelist); |
269 | if (unlikely(!new_bucket)) |
270 | return -ENOMEM; |
271 | memcpy(new_bucket->data, ips, trace_len); |
272 | } |
273 | |
274 | new_bucket->hash = hash; |
275 | new_bucket->nr = trace_nr; |
276 | |
277 | old_bucket = xchg(&smap->buckets[id], new_bucket); |
278 | if (old_bucket) |
279 | pcpu_freelist_push(&smap->freelist, &old_bucket->fnode); |
280 | return id; |
281 | } |
282 | |
283 | BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map, |
284 | u64, flags) |
285 | { |
286 | u32 max_depth = map->value_size / stack_map_data_size(map); |
287 | u32 skip = flags & BPF_F_SKIP_FIELD_MASK; |
288 | bool user = flags & BPF_F_USER_STACK; |
289 | struct perf_callchain_entry *trace; |
290 | bool kernel = !user; |
291 | |
292 | if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | |
293 | BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID))) |
294 | return -EINVAL; |
295 | |
296 | max_depth += skip; |
297 | if (max_depth > sysctl_perf_event_max_stack) |
298 | max_depth = sysctl_perf_event_max_stack; |
299 | |
300 | trace = get_perf_callchain(regs, init_nr: 0, kernel, user, max_stack: max_depth, |
301 | crosstask: false, add_mark: false); |
302 | |
303 | if (unlikely(!trace)) |
304 | /* couldn't fetch the stack trace */ |
305 | return -EFAULT; |
306 | |
307 | return __bpf_get_stackid(map, trace, flags); |
308 | } |
309 | |
310 | const struct bpf_func_proto bpf_get_stackid_proto = { |
311 | .func = bpf_get_stackid, |
312 | .gpl_only = true, |
313 | .ret_type = RET_INTEGER, |
314 | .arg1_type = ARG_PTR_TO_CTX, |
315 | .arg2_type = ARG_CONST_MAP_PTR, |
316 | .arg3_type = ARG_ANYTHING, |
317 | }; |
318 | |
319 | static __u64 count_kernel_ip(struct perf_callchain_entry *trace) |
320 | { |
321 | __u64 nr_kernel = 0; |
322 | |
323 | while (nr_kernel < trace->nr) { |
324 | if (trace->ip[nr_kernel] == PERF_CONTEXT_USER) |
325 | break; |
326 | nr_kernel++; |
327 | } |
328 | return nr_kernel; |
329 | } |
330 | |
331 | BPF_CALL_3(bpf_get_stackid_pe, struct bpf_perf_event_data_kern *, ctx, |
332 | struct bpf_map *, map, u64, flags) |
333 | { |
334 | struct perf_event *event = ctx->event; |
335 | struct perf_callchain_entry *trace; |
336 | bool kernel, user; |
337 | __u64 nr_kernel; |
338 | int ret; |
339 | |
340 | /* perf_sample_data doesn't have callchain, use bpf_get_stackid */ |
341 | if (!(event->attr.sample_type & PERF_SAMPLE_CALLCHAIN)) |
342 | return bpf_get_stackid(regs: (unsigned long)(ctx->regs), |
343 | map: (unsigned long) map, flags, ur_1: 0, ur_2: 0); |
344 | |
345 | if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | |
346 | BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID))) |
347 | return -EINVAL; |
348 | |
349 | user = flags & BPF_F_USER_STACK; |
350 | kernel = !user; |
351 | |
352 | trace = ctx->data->callchain; |
353 | if (unlikely(!trace)) |
354 | return -EFAULT; |
355 | |
356 | nr_kernel = count_kernel_ip(trace); |
357 | |
358 | if (kernel) { |
359 | __u64 nr = trace->nr; |
360 | |
361 | trace->nr = nr_kernel; |
362 | ret = __bpf_get_stackid(map, trace, flags); |
363 | |
364 | /* restore nr */ |
365 | trace->nr = nr; |
366 | } else { /* user */ |
367 | u64 skip = flags & BPF_F_SKIP_FIELD_MASK; |
368 | |
369 | skip += nr_kernel; |
370 | if (skip > BPF_F_SKIP_FIELD_MASK) |
371 | return -EFAULT; |
372 | |
373 | flags = (flags & ~BPF_F_SKIP_FIELD_MASK) | skip; |
374 | ret = __bpf_get_stackid(map, trace, flags); |
375 | } |
376 | return ret; |
377 | } |
378 | |
379 | const struct bpf_func_proto bpf_get_stackid_proto_pe = { |
380 | .func = bpf_get_stackid_pe, |
381 | .gpl_only = false, |
382 | .ret_type = RET_INTEGER, |
383 | .arg1_type = ARG_PTR_TO_CTX, |
384 | .arg2_type = ARG_CONST_MAP_PTR, |
385 | .arg3_type = ARG_ANYTHING, |
386 | }; |
387 | |
388 | static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task, |
389 | struct perf_callchain_entry *trace_in, |
390 | void *buf, u32 size, u64 flags) |
391 | { |
392 | u32 trace_nr, copy_len, elem_size, num_elem, max_depth; |
393 | bool user_build_id = flags & BPF_F_USER_BUILD_ID; |
394 | bool crosstask = task && task != current; |
395 | u32 skip = flags & BPF_F_SKIP_FIELD_MASK; |
396 | bool user = flags & BPF_F_USER_STACK; |
397 | struct perf_callchain_entry *trace; |
398 | bool kernel = !user; |
399 | int err = -EINVAL; |
400 | u64 *ips; |
401 | |
402 | if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | |
403 | BPF_F_USER_BUILD_ID))) |
404 | goto clear; |
405 | if (kernel && user_build_id) |
406 | goto clear; |
407 | |
408 | elem_size = (user && user_build_id) ? sizeof(struct bpf_stack_build_id) |
409 | : sizeof(u64); |
410 | if (unlikely(size % elem_size)) |
411 | goto clear; |
412 | |
413 | /* cannot get valid user stack for task without user_mode regs */ |
414 | if (task && user && !user_mode(regs)) |
415 | goto err_fault; |
416 | |
417 | /* get_perf_callchain does not support crosstask user stack walking |
418 | * but returns an empty stack instead of NULL. |
419 | */ |
420 | if (crosstask && user) { |
421 | err = -EOPNOTSUPP; |
422 | goto clear; |
423 | } |
424 | |
425 | num_elem = size / elem_size; |
426 | max_depth = num_elem + skip; |
427 | if (sysctl_perf_event_max_stack < max_depth) |
428 | max_depth = sysctl_perf_event_max_stack; |
429 | |
430 | if (trace_in) |
431 | trace = trace_in; |
432 | else if (kernel && task) |
433 | trace = get_callchain_entry_for_task(task, max_depth); |
434 | else |
435 | trace = get_perf_callchain(regs, init_nr: 0, kernel, user, max_stack: max_depth, |
436 | crosstask, add_mark: false); |
437 | if (unlikely(!trace)) |
438 | goto err_fault; |
439 | |
440 | if (trace->nr < skip) |
441 | goto err_fault; |
442 | |
443 | trace_nr = trace->nr - skip; |
444 | trace_nr = (trace_nr <= num_elem) ? trace_nr : num_elem; |
445 | copy_len = trace_nr * elem_size; |
446 | |
447 | ips = trace->ip + skip; |
448 | if (user && user_build_id) |
449 | stack_map_get_build_id_offset(id_offs: buf, ips, trace_nr, user); |
450 | else |
451 | memcpy(buf, ips, copy_len); |
452 | |
453 | if (size > copy_len) |
454 | memset(buf + copy_len, 0, size - copy_len); |
455 | return copy_len; |
456 | |
457 | err_fault: |
458 | err = -EFAULT; |
459 | clear: |
460 | memset(buf, 0, size); |
461 | return err; |
462 | } |
463 | |
464 | BPF_CALL_4(bpf_get_stack, struct pt_regs *, regs, void *, buf, u32, size, |
465 | u64, flags) |
466 | { |
467 | return __bpf_get_stack(regs, NULL, NULL, buf, size, flags); |
468 | } |
469 | |
470 | const struct bpf_func_proto bpf_get_stack_proto = { |
471 | .func = bpf_get_stack, |
472 | .gpl_only = true, |
473 | .ret_type = RET_INTEGER, |
474 | .arg1_type = ARG_PTR_TO_CTX, |
475 | .arg2_type = ARG_PTR_TO_UNINIT_MEM, |
476 | .arg3_type = ARG_CONST_SIZE_OR_ZERO, |
477 | .arg4_type = ARG_ANYTHING, |
478 | }; |
479 | |
480 | BPF_CALL_4(bpf_get_task_stack, struct task_struct *, task, void *, buf, |
481 | u32, size, u64, flags) |
482 | { |
483 | struct pt_regs *regs; |
484 | long res = -EINVAL; |
485 | |
486 | if (!try_get_task_stack(tsk: task)) |
487 | return -EFAULT; |
488 | |
489 | regs = task_pt_regs(task); |
490 | if (regs) |
491 | res = __bpf_get_stack(regs, task, NULL, buf, size, flags); |
492 | put_task_stack(tsk: task); |
493 | |
494 | return res; |
495 | } |
496 | |
497 | const struct bpf_func_proto bpf_get_task_stack_proto = { |
498 | .func = bpf_get_task_stack, |
499 | .gpl_only = false, |
500 | .ret_type = RET_INTEGER, |
501 | .arg1_type = ARG_PTR_TO_BTF_ID, |
502 | .arg1_btf_id = &btf_tracing_ids[BTF_TRACING_TYPE_TASK], |
503 | .arg2_type = ARG_PTR_TO_UNINIT_MEM, |
504 | .arg3_type = ARG_CONST_SIZE_OR_ZERO, |
505 | .arg4_type = ARG_ANYTHING, |
506 | }; |
507 | |
508 | BPF_CALL_4(bpf_get_stack_pe, struct bpf_perf_event_data_kern *, ctx, |
509 | void *, buf, u32, size, u64, flags) |
510 | { |
511 | struct pt_regs *regs = (struct pt_regs *)(ctx->regs); |
512 | struct perf_event *event = ctx->event; |
513 | struct perf_callchain_entry *trace; |
514 | bool kernel, user; |
515 | int err = -EINVAL; |
516 | __u64 nr_kernel; |
517 | |
518 | if (!(event->attr.sample_type & PERF_SAMPLE_CALLCHAIN)) |
519 | return __bpf_get_stack(regs, NULL, NULL, buf, size, flags); |
520 | |
521 | if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | |
522 | BPF_F_USER_BUILD_ID))) |
523 | goto clear; |
524 | |
525 | user = flags & BPF_F_USER_STACK; |
526 | kernel = !user; |
527 | |
528 | err = -EFAULT; |
529 | trace = ctx->data->callchain; |
530 | if (unlikely(!trace)) |
531 | goto clear; |
532 | |
533 | nr_kernel = count_kernel_ip(trace); |
534 | |
535 | if (kernel) { |
536 | __u64 nr = trace->nr; |
537 | |
538 | trace->nr = nr_kernel; |
539 | err = __bpf_get_stack(regs, NULL, trace_in: trace, buf, size, flags); |
540 | |
541 | /* restore nr */ |
542 | trace->nr = nr; |
543 | } else { /* user */ |
544 | u64 skip = flags & BPF_F_SKIP_FIELD_MASK; |
545 | |
546 | skip += nr_kernel; |
547 | if (skip > BPF_F_SKIP_FIELD_MASK) |
548 | goto clear; |
549 | |
550 | flags = (flags & ~BPF_F_SKIP_FIELD_MASK) | skip; |
551 | err = __bpf_get_stack(regs, NULL, trace_in: trace, buf, size, flags); |
552 | } |
553 | return err; |
554 | |
555 | clear: |
556 | memset(buf, 0, size); |
557 | return err; |
558 | |
559 | } |
560 | |
561 | const struct bpf_func_proto bpf_get_stack_proto_pe = { |
562 | .func = bpf_get_stack_pe, |
563 | .gpl_only = true, |
564 | .ret_type = RET_INTEGER, |
565 | .arg1_type = ARG_PTR_TO_CTX, |
566 | .arg2_type = ARG_PTR_TO_UNINIT_MEM, |
567 | .arg3_type = ARG_CONST_SIZE_OR_ZERO, |
568 | .arg4_type = ARG_ANYTHING, |
569 | }; |
570 | |
571 | /* Called from eBPF program */ |
572 | static void *stack_map_lookup_elem(struct bpf_map *map, void *key) |
573 | { |
574 | return ERR_PTR(error: -EOPNOTSUPP); |
575 | } |
576 | |
577 | /* Called from syscall */ |
578 | int bpf_stackmap_copy(struct bpf_map *map, void *key, void *value) |
579 | { |
580 | struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); |
581 | struct stack_map_bucket *bucket, *old_bucket; |
582 | u32 id = *(u32 *)key, trace_len; |
583 | |
584 | if (unlikely(id >= smap->n_buckets)) |
585 | return -ENOENT; |
586 | |
587 | bucket = xchg(&smap->buckets[id], NULL); |
588 | if (!bucket) |
589 | return -ENOENT; |
590 | |
591 | trace_len = bucket->nr * stack_map_data_size(map); |
592 | memcpy(value, bucket->data, trace_len); |
593 | memset(value + trace_len, 0, map->value_size - trace_len); |
594 | |
595 | old_bucket = xchg(&smap->buckets[id], bucket); |
596 | if (old_bucket) |
597 | pcpu_freelist_push(&smap->freelist, &old_bucket->fnode); |
598 | return 0; |
599 | } |
600 | |
601 | static int stack_map_get_next_key(struct bpf_map *map, void *key, |
602 | void *next_key) |
603 | { |
604 | struct bpf_stack_map *smap = container_of(map, |
605 | struct bpf_stack_map, map); |
606 | u32 id; |
607 | |
608 | WARN_ON_ONCE(!rcu_read_lock_held()); |
609 | |
610 | if (!key) { |
611 | id = 0; |
612 | } else { |
613 | id = *(u32 *)key; |
614 | if (id >= smap->n_buckets || !smap->buckets[id]) |
615 | id = 0; |
616 | else |
617 | id++; |
618 | } |
619 | |
620 | while (id < smap->n_buckets && !smap->buckets[id]) |
621 | id++; |
622 | |
623 | if (id >= smap->n_buckets) |
624 | return -ENOENT; |
625 | |
626 | *(u32 *)next_key = id; |
627 | return 0; |
628 | } |
629 | |
630 | static long stack_map_update_elem(struct bpf_map *map, void *key, void *value, |
631 | u64 map_flags) |
632 | { |
633 | return -EINVAL; |
634 | } |
635 | |
636 | /* Called from syscall or from eBPF program */ |
637 | static long stack_map_delete_elem(struct bpf_map *map, void *key) |
638 | { |
639 | struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); |
640 | struct stack_map_bucket *old_bucket; |
641 | u32 id = *(u32 *)key; |
642 | |
643 | if (unlikely(id >= smap->n_buckets)) |
644 | return -E2BIG; |
645 | |
646 | old_bucket = xchg(&smap->buckets[id], NULL); |
647 | if (old_bucket) { |
648 | pcpu_freelist_push(&smap->freelist, &old_bucket->fnode); |
649 | return 0; |
650 | } else { |
651 | return -ENOENT; |
652 | } |
653 | } |
654 | |
655 | /* Called when map->refcnt goes to zero, either from workqueue or from syscall */ |
656 | static void stack_map_free(struct bpf_map *map) |
657 | { |
658 | struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); |
659 | |
660 | bpf_map_area_free(base: smap->elems); |
661 | pcpu_freelist_destroy(s: &smap->freelist); |
662 | bpf_map_area_free(base: smap); |
663 | put_callchain_buffers(); |
664 | } |
665 | |
666 | static u64 stack_map_mem_usage(const struct bpf_map *map) |
667 | { |
668 | struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); |
669 | u64 value_size = map->value_size; |
670 | u64 n_buckets = smap->n_buckets; |
671 | u64 enties = map->max_entries; |
672 | u64 usage = sizeof(*smap); |
673 | |
674 | usage += n_buckets * sizeof(struct stack_map_bucket *); |
675 | usage += enties * (sizeof(struct stack_map_bucket) + value_size); |
676 | return usage; |
677 | } |
678 | |
679 | BTF_ID_LIST_SINGLE(stack_trace_map_btf_ids, struct, bpf_stack_map) |
680 | const struct bpf_map_ops stack_trace_map_ops = { |
681 | .map_meta_equal = bpf_map_meta_equal, |
682 | .map_alloc = stack_map_alloc, |
683 | .map_free = stack_map_free, |
684 | .map_get_next_key = stack_map_get_next_key, |
685 | .map_lookup_elem = stack_map_lookup_elem, |
686 | .map_update_elem = stack_map_update_elem, |
687 | .map_delete_elem = stack_map_delete_elem, |
688 | .map_check_btf = map_check_no_btf, |
689 | .map_mem_usage = stack_map_mem_usage, |
690 | .map_btf_id = &stack_trace_map_btf_ids[0], |
691 | }; |
692 | |