projects/linux·blob v5.12-rc5 · refs

721 lines · 18.4 KiB

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/irq_work.h>
11#include <linux/btf_ids.h>
12#include <linux/buildid.h>
13#include "percpu_freelist.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
19struct stack_map_bucket {
20 struct pcpu_freelist_node fnode;
21 u32 hash;
22 u32 nr;
23 u64 data[];
24};
25
26struct 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[];
32};
33
34/* irq_work to run up_read() for build_id lookup in nmi context */
35struct stack_map_irq_work {
36 struct irq_work irq_work;
37 struct mm_struct *mm;
38};
39
40static void do_up_read(struct irq_work *entry)
41{
42 struct stack_map_irq_work *work;
43
44 if (WARN_ON_ONCE(IS_ENABLED(CONFIG_PREEMPT_RT)))
45 return;
46
47 work = container_of(entry, struct stack_map_irq_work, irq_work);
48 mmap_read_unlock_non_owner(work->mm);
49}
50
51static DEFINE_PER_CPU(struct stack_map_irq_work, up_read_work);
52
53static inline bool stack_map_use_build_id(struct bpf_map *map)
54{
55 return (map->map_flags & BPF_F_STACK_BUILD_ID);
56}
57
58static inline int stack_map_data_size(struct bpf_map *map)
59{
60 return stack_map_use_build_id(map) ?
61 sizeof(struct bpf_stack_build_id) : sizeof(u64);
62}
63
64static int prealloc_elems_and_freelist(struct bpf_stack_map *smap)
65{
66 u32 elem_size = sizeof(struct stack_map_bucket) + smap->map.value_size;
67 int err;
68
69 smap->elems = bpf_map_area_alloc(elem_size * smap->map.max_entries,
70 smap->map.numa_node);
71 if (!smap->elems)
72 return -ENOMEM;
73
74 err = pcpu_freelist_init(&smap->freelist);
75 if (err)
76 goto free_elems;
77
78 pcpu_freelist_populate(&smap->freelist, smap->elems, elem_size,
79 smap->map.max_entries);
80 return 0;
81
82free_elems:
83 bpf_map_area_free(smap->elems);
84 return err;
85}
86
87/* Called from syscall */
88static struct bpf_map *stack_map_alloc(union bpf_attr *attr)
89{
90 u32 value_size = attr->value_size;
91 struct bpf_stack_map *smap;
92 u64 cost, n_buckets;
93 int err;
94
95 if (!bpf_capable())
96 return ERR_PTR(-EPERM);
97
98 if (attr->map_flags & ~STACK_CREATE_FLAG_MASK)
99 return ERR_PTR(-EINVAL);
100
101 /* check sanity of attributes */
102 if (attr->max_entries == 0 || attr->key_size != 4 ||
103 value_size < 8 || value_size % 8)
104 return ERR_PTR(-EINVAL);
105
106 BUILD_BUG_ON(sizeof(struct bpf_stack_build_id) % sizeof(u64));
107 if (attr->map_flags & BPF_F_STACK_BUILD_ID) {
108 if (value_size % sizeof(struct bpf_stack_build_id) ||
109 value_size / sizeof(struct bpf_stack_build_id)
110 > sysctl_perf_event_max_stack)
111 return ERR_PTR(-EINVAL);
112 } else if (value_size / 8 > sysctl_perf_event_max_stack)
113 return ERR_PTR(-EINVAL);
114
115 /* hash table size must be power of 2 */
116 n_buckets = roundup_pow_of_two(attr->max_entries);
117 if (!n_buckets)
118 return ERR_PTR(-E2BIG);
119
120 cost = n_buckets * sizeof(struct stack_map_bucket *) + sizeof(*smap);
121 cost += n_buckets * (value_size + sizeof(struct stack_map_bucket));
122 smap = bpf_map_area_alloc(cost, bpf_map_attr_numa_node(attr));
123 if (!smap)
124 return ERR_PTR(-ENOMEM);
125
126 bpf_map_init_from_attr(&smap->map, attr);
127 smap->map.value_size = value_size;
128 smap->n_buckets = n_buckets;
129
130 err = get_callchain_buffers(sysctl_perf_event_max_stack);
131 if (err)
132 goto free_smap;
133
134 err = prealloc_elems_and_freelist(smap);
135 if (err)
136 goto put_buffers;
137
138 return &smap->map;
139
140put_buffers:
141 put_callchain_buffers();
142free_smap:
143 bpf_map_area_free(smap);
144 return ERR_PTR(err);
145}
146
147static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs,
148 u64 *ips, u32 trace_nr, bool user)
149{
150 int i;
151 struct vm_area_struct *vma;
152 bool irq_work_busy = false;
153 struct stack_map_irq_work *work = NULL;
154
155 if (irqs_disabled()) {
156 if (!IS_ENABLED(CONFIG_PREEMPT_RT)) {
157 work = this_cpu_ptr(&up_read_work);
158 if (irq_work_is_busy(&work->irq_work)) {
159 /* cannot queue more up_read, fallback */
160 irq_work_busy = true;
161 }
162 } else {
163 /*
164 * PREEMPT_RT does not allow to trylock mmap sem in
165 * interrupt disabled context. Force the fallback code.
166 */
167 irq_work_busy = true;
168 }
169 }
170
171 /*
172 * We cannot do up_read() when the irq is disabled, because of
173 * risk to deadlock with rq_lock. To do build_id lookup when the
174 * irqs are disabled, we need to run up_read() in irq_work. We use
175 * a percpu variable to do the irq_work. If the irq_work is
176 * already used by another lookup, we fall back to report ips.
177 *
178 * Same fallback is used for kernel stack (!user) on a stackmap
179 * with build_id.
180 */
181 if (!user || !current || !current->mm || irq_work_busy ||
182 !mmap_read_trylock_non_owner(current->mm)) {
183 /* cannot access current->mm, fall back to ips */
184 for (i = 0; i < trace_nr; i++) {
185 id_offs[i].status = BPF_STACK_BUILD_ID_IP;
186 id_offs[i].ip = ips[i];
187 memset(id_offs[i].build_id, 0, BUILD_ID_SIZE_MAX);
188 }
189 return;
190 }
191
192 for (i = 0; i < trace_nr; i++) {
193 vma = find_vma(current->mm, ips[i]);
194 if (!vma || build_id_parse(vma, id_offs[i].build_id, NULL)) {
195 /* per entry fall back to ips */
196 id_offs[i].status = BPF_STACK_BUILD_ID_IP;
197 id_offs[i].ip = ips[i];
198 memset(id_offs[i].build_id, 0, BUILD_ID_SIZE_MAX);
199 continue;
200 }
201 id_offs[i].offset = (vma->vm_pgoff << PAGE_SHIFT) + ips[i]
202 - vma->vm_start;
203 id_offs[i].status = BPF_STACK_BUILD_ID_VALID;
204 }
205
206 if (!work) {
207 mmap_read_unlock_non_owner(current->mm);
208 } else {
209 work->mm = current->mm;
210 irq_work_queue(&work->irq_work);
211 }
212}
213
214static struct perf_callchain_entry *
215get_callchain_entry_for_task(struct task_struct *task, u32 init_nr)
216{
217#ifdef CONFIG_STACKTRACE
218 struct perf_callchain_entry *entry;
219 int rctx;
220
221 entry = get_callchain_entry(&rctx);
222
223 if (!entry)
224 return NULL;
225
226 entry->nr = init_nr +
227 stack_trace_save_tsk(task, (unsigned long *)(entry->ip + init_nr),
228 sysctl_perf_event_max_stack - init_nr, 0);
229
230 /* stack_trace_save_tsk() works on unsigned long array, while
231 * perf_callchain_entry uses u64 array. For 32-bit systems, it is
232 * necessary to fix this mismatch.
233 */
234 if (__BITS_PER_LONG != 64) {
235 unsigned long *from = (unsigned long *) entry->ip;
236 u64 *to = entry->ip;
237 int i;
238
239 /* copy data from the end to avoid using extra buffer */
240 for (i = entry->nr - 1; i >= (int)init_nr; i--)
241 to[i] = (u64)(from[i]);
242 }
243
244 put_callchain_entry(rctx);
245
246 return entry;
247#else /* CONFIG_STACKTRACE */
248 return NULL;
249#endif
250}
251
252static long __bpf_get_stackid(struct bpf_map *map,
253 struct perf_callchain_entry *trace, u64 flags)
254{
255 struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);
256 struct stack_map_bucket *bucket, *new_bucket, *old_bucket;
257 u32 max_depth = map->value_size / stack_map_data_size(map);
258 /* stack_map_alloc() checks that max_depth <= sysctl_perf_event_max_stack */
259 u32 init_nr = sysctl_perf_event_max_stack - max_depth;
260 u32 skip = flags & BPF_F_SKIP_FIELD_MASK;
261 u32 hash, id, trace_nr, trace_len;
262 bool user = flags & BPF_F_USER_STACK;
263 u64 *ips;
264 bool hash_matches;
265
266 /* get_perf_callchain() guarantees that trace->nr >= init_nr
267 * and trace-nr <= sysctl_perf_event_max_stack, so trace_nr <= max_depth
268 */
269 trace_nr = trace->nr - init_nr;
270
271 if (trace_nr <= skip)
272 /* skipping more than usable stack trace */
273 return -EFAULT;
274
275 trace_nr -= skip;
276 trace_len = trace_nr * sizeof(u64);
277 ips = trace->ip + skip + init_nr;
278 hash = jhash2((u32 *)ips, trace_len / sizeof(u32), 0);
279 id = hash & (smap->n_buckets - 1);
280 bucket = READ_ONCE(smap->buckets[id]);
281
282 hash_matches = bucket && bucket->hash == hash;
283 /* fast cmp */
284 if (hash_matches && flags & BPF_F_FAST_STACK_CMP)
285 return id;
286
287 if (stack_map_use_build_id(map)) {
288 /* for build_id+offset, pop a bucket before slow cmp */
289 new_bucket = (struct stack_map_bucket *)
290 pcpu_freelist_pop(&smap->freelist);
291 if (unlikely(!new_bucket))
292 return -ENOMEM;
293 new_bucket->nr = trace_nr;
294 stack_map_get_build_id_offset(
295 (struct bpf_stack_build_id *)new_bucket->data,
296 ips, trace_nr, user);
297 trace_len = trace_nr * sizeof(struct bpf_stack_build_id);
298 if (hash_matches && bucket->nr == trace_nr &&
299 memcmp(bucket->data, new_bucket->data, trace_len) == 0) {
300 pcpu_freelist_push(&smap->freelist, &new_bucket->fnode);
301 return id;
302 }
303 if (bucket && !(flags & BPF_F_REUSE_STACKID)) {
304 pcpu_freelist_push(&smap->freelist, &new_bucket->fnode);
305 return -EEXIST;
306 }
307 } else {
308 if (hash_matches && bucket->nr == trace_nr &&
309 memcmp(bucket->data, ips, trace_len) == 0)
310 return id;
311 if (bucket && !(flags & BPF_F_REUSE_STACKID))
312 return -EEXIST;
313
314 new_bucket = (struct stack_map_bucket *)
315 pcpu_freelist_pop(&smap->freelist);
316 if (unlikely(!new_bucket))
317 return -ENOMEM;
318 memcpy(new_bucket->data, ips, trace_len);
319 }
320
321 new_bucket->hash = hash;
322 new_bucket->nr = trace_nr;
323
324 old_bucket = xchg(&smap->buckets[id], new_bucket);
325 if (old_bucket)
326 pcpu_freelist_push(&smap->freelist, &old_bucket->fnode);
327 return id;
328}
329
330BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map,
331 u64, flags)
332{
333 u32 max_depth = map->value_size / stack_map_data_size(map);
334 /* stack_map_alloc() checks that max_depth <= sysctl_perf_event_max_stack */
335 u32 init_nr = sysctl_perf_event_max_stack - max_depth;
336 bool user = flags & BPF_F_USER_STACK;
337 struct perf_callchain_entry *trace;
338 bool kernel = !user;
339
340 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
341 BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID)))
342 return -EINVAL;
343
344 trace = get_perf_callchain(regs, init_nr, kernel, user,
345 sysctl_perf_event_max_stack, false, false);
346
347 if (unlikely(!trace))
348 /* couldn't fetch the stack trace */
349 return -EFAULT;
350
351 return __bpf_get_stackid(map, trace, flags);
352}
353
354const struct bpf_func_proto bpf_get_stackid_proto = {
355 .func = bpf_get_stackid,
356 .gpl_only = true,
357 .ret_type = RET_INTEGER,
358 .arg1_type = ARG_PTR_TO_CTX,
359 .arg2_type = ARG_CONST_MAP_PTR,
360 .arg3_type = ARG_ANYTHING,
361};
362
363static __u64 count_kernel_ip(struct perf_callchain_entry *trace)
364{
365 __u64 nr_kernel = 0;
366
367 while (nr_kernel < trace->nr) {
368 if (trace->ip[nr_kernel] == PERF_CONTEXT_USER)
369 break;
370 nr_kernel++;
371 }
372 return nr_kernel;
373}
374
375BPF_CALL_3(bpf_get_stackid_pe, struct bpf_perf_event_data_kern *, ctx,
376 struct bpf_map *, map, u64, flags)
377{
378 struct perf_event *event = ctx->event;
379 struct perf_callchain_entry *trace;
380 bool kernel, user;
381 __u64 nr_kernel;
382 int ret;
383
384 /* perf_sample_data doesn't have callchain, use bpf_get_stackid */
385 if (!(event->attr.sample_type & __PERF_SAMPLE_CALLCHAIN_EARLY))
386 return bpf_get_stackid((unsigned long)(ctx->regs),
387 (unsigned long) map, flags, 0, 0);
388
389 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
390 BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID)))
391 return -EINVAL;
392
393 user = flags & BPF_F_USER_STACK;
394 kernel = !user;
395
396 trace = ctx->data->callchain;
397 if (unlikely(!trace))
398 return -EFAULT;
399
400 nr_kernel = count_kernel_ip(trace);
401
402 if (kernel) {
403 __u64 nr = trace->nr;
404
405 trace->nr = nr_kernel;
406 ret = __bpf_get_stackid(map, trace, flags);
407
408 /* restore nr */
409 trace->nr = nr;
410 } else { /* user */
411 u64 skip = flags & BPF_F_SKIP_FIELD_MASK;
412
413 skip += nr_kernel;
414 if (skip > BPF_F_SKIP_FIELD_MASK)
415 return -EFAULT;
416
417 flags = (flags & ~BPF_F_SKIP_FIELD_MASK) | skip;
418 ret = __bpf_get_stackid(map, trace, flags);
419 }
420 return ret;
421}
422
423const struct bpf_func_proto bpf_get_stackid_proto_pe = {
424 .func = bpf_get_stackid_pe,
425 .gpl_only = false,
426 .ret_type = RET_INTEGER,
427 .arg1_type = ARG_PTR_TO_CTX,
428 .arg2_type = ARG_CONST_MAP_PTR,
429 .arg3_type = ARG_ANYTHING,
430};
431
432static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task,
433 struct perf_callchain_entry *trace_in,
434 void *buf, u32 size, u64 flags)
435{
436 u32 init_nr, trace_nr, copy_len, elem_size, num_elem;
437 bool user_build_id = flags & BPF_F_USER_BUILD_ID;
438 u32 skip = flags & BPF_F_SKIP_FIELD_MASK;
439 bool user = flags & BPF_F_USER_STACK;
440 struct perf_callchain_entry *trace;
441 bool kernel = !user;
442 int err = -EINVAL;
443 u64 *ips;
444
445 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
446 BPF_F_USER_BUILD_ID)))
447 goto clear;
448 if (kernel && user_build_id)
449 goto clear;
450
451 elem_size = (user && user_build_id) ? sizeof(struct bpf_stack_build_id)
452 : sizeof(u64);
453 if (unlikely(size % elem_size))
454 goto clear;
455
456 /* cannot get valid user stack for task without user_mode regs */
457 if (task && user && !user_mode(regs))
458 goto err_fault;
459
460 num_elem = size / elem_size;
461 if (sysctl_perf_event_max_stack < num_elem)
462 init_nr = 0;
463 else
464 init_nr = sysctl_perf_event_max_stack - num_elem;
465
466 if (trace_in)
467 trace = trace_in;
468 else if (kernel && task)
469 trace = get_callchain_entry_for_task(task, init_nr);
470 else
471 trace = get_perf_callchain(regs, init_nr, kernel, user,
472 sysctl_perf_event_max_stack,
473 false, false);
474 if (unlikely(!trace))
475 goto err_fault;
476
477 trace_nr = trace->nr - init_nr;
478 if (trace_nr < skip)
479 goto err_fault;
480
481 trace_nr -= skip;
482 trace_nr = (trace_nr <= num_elem) ? trace_nr : num_elem;
483 copy_len = trace_nr * elem_size;
484 ips = trace->ip + skip + init_nr;
485 if (user && user_build_id)
486 stack_map_get_build_id_offset(buf, ips, trace_nr, user);
487 else
488 memcpy(buf, ips, copy_len);
489
490 if (size > copy_len)
491 memset(buf + copy_len, 0, size - copy_len);
492 return copy_len;
493
494err_fault:
495 err = -EFAULT;
496clear:
497 memset(buf, 0, size);
498 return err;
499}
500
501BPF_CALL_4(bpf_get_stack, struct pt_regs *, regs, void *, buf, u32, size,
502 u64, flags)
503{
504 return __bpf_get_stack(regs, NULL, NULL, buf, size, flags);
505}
506
507const struct bpf_func_proto bpf_get_stack_proto = {
508 .func = bpf_get_stack,
509 .gpl_only = true,
510 .ret_type = RET_INTEGER,
511 .arg1_type = ARG_PTR_TO_CTX,
512 .arg2_type = ARG_PTR_TO_UNINIT_MEM,
513 .arg3_type = ARG_CONST_SIZE_OR_ZERO,
514 .arg4_type = ARG_ANYTHING,
515};
516
517BPF_CALL_4(bpf_get_task_stack, struct task_struct *, task, void *, buf,
518 u32, size, u64, flags)
519{
520 struct pt_regs *regs = task_pt_regs(task);
521
522 return __bpf_get_stack(regs, task, NULL, buf, size, flags);
523}
524
525BTF_ID_LIST_SINGLE(bpf_get_task_stack_btf_ids, struct, task_struct)
526
527const struct bpf_func_proto bpf_get_task_stack_proto = {
528 .func = bpf_get_task_stack,
529 .gpl_only = false,
530 .ret_type = RET_INTEGER,
531 .arg1_type = ARG_PTR_TO_BTF_ID,
532 .arg1_btf_id = &bpf_get_task_stack_btf_ids[0],
533 .arg2_type = ARG_PTR_TO_UNINIT_MEM,
534 .arg3_type = ARG_CONST_SIZE_OR_ZERO,
535 .arg4_type = ARG_ANYTHING,
536};
537
538BPF_CALL_4(bpf_get_stack_pe, struct bpf_perf_event_data_kern *, ctx,
539 void *, buf, u32, size, u64, flags)
540{
541 struct pt_regs *regs = (struct pt_regs *)(ctx->regs);
542 struct perf_event *event = ctx->event;
543 struct perf_callchain_entry *trace;
544 bool kernel, user;
545 int err = -EINVAL;
546 __u64 nr_kernel;
547
548 if (!(event->attr.sample_type & __PERF_SAMPLE_CALLCHAIN_EARLY))
549 return __bpf_get_stack(regs, NULL, NULL, buf, size, flags);
550
551 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
552 BPF_F_USER_BUILD_ID)))
553 goto clear;
554
555 user = flags & BPF_F_USER_STACK;
556 kernel = !user;
557
558 err = -EFAULT;
559 trace = ctx->data->callchain;
560 if (unlikely(!trace))
561 goto clear;
562
563 nr_kernel = count_kernel_ip(trace);
564
565 if (kernel) {
566 __u64 nr = trace->nr;
567
568 trace->nr = nr_kernel;
569 err = __bpf_get_stack(regs, NULL, trace, buf, size, flags);
570
571 /* restore nr */
572 trace->nr = nr;
573 } else { /* user */
574 u64 skip = flags & BPF_F_SKIP_FIELD_MASK;
575
576 skip += nr_kernel;
577 if (skip > BPF_F_SKIP_FIELD_MASK)
578 goto clear;
579
580 flags = (flags & ~BPF_F_SKIP_FIELD_MASK) | skip;
581 err = __bpf_get_stack(regs, NULL, trace, buf, size, flags);
582 }
583 return err;
584
585clear:
586 memset(buf, 0, size);
587 return err;
588
589}
590
591const struct bpf_func_proto bpf_get_stack_proto_pe = {
592 .func = bpf_get_stack_pe,
593 .gpl_only = true,
594 .ret_type = RET_INTEGER,
595 .arg1_type = ARG_PTR_TO_CTX,
596 .arg2_type = ARG_PTR_TO_UNINIT_MEM,
597 .arg3_type = ARG_CONST_SIZE_OR_ZERO,
598 .arg4_type = ARG_ANYTHING,
599};
600
601/* Called from eBPF program */
602static void *stack_map_lookup_elem(struct bpf_map *map, void *key)
603{
604 return ERR_PTR(-EOPNOTSUPP);
605}
606
607/* Called from syscall */
608int bpf_stackmap_copy(struct bpf_map *map, void *key, void *value)
609{
610 struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);
611 struct stack_map_bucket *bucket, *old_bucket;
612 u32 id = *(u32 *)key, trace_len;
613
614 if (unlikely(id >= smap->n_buckets))
615 return -ENOENT;
616
617 bucket = xchg(&smap->buckets[id], NULL);
618 if (!bucket)
619 return -ENOENT;
620
621 trace_len = bucket->nr * stack_map_data_size(map);
622 memcpy(value, bucket->data, trace_len);
623 memset(value + trace_len, 0, map->value_size - trace_len);
624
625 old_bucket = xchg(&smap->buckets[id], bucket);
626 if (old_bucket)
627 pcpu_freelist_push(&smap->freelist, &old_bucket->fnode);
628 return 0;
629}
630
631static int stack_map_get_next_key(struct bpf_map *map, void *key,
632 void *next_key)
633{
634 struct bpf_stack_map *smap = container_of(map,
635 struct bpf_stack_map, map);
636 u32 id;
637
638 WARN_ON_ONCE(!rcu_read_lock_held());
639
640 if (!key) {
641 id = 0;
642 } else {
643 id = *(u32 *)key;
644 if (id >= smap->n_buckets || !smap->buckets[id])
645 id = 0;
646 else
647 id++;
648 }
649
650 while (id < smap->n_buckets && !smap->buckets[id])
651 id++;
652
653 if (id >= smap->n_buckets)
654 return -ENOENT;
655
656 *(u32 *)next_key = id;
657 return 0;
658}
659
660static int stack_map_update_elem(struct bpf_map *map, void *key, void *value,
661 u64 map_flags)
662{
663 return -EINVAL;
664}
665
666/* Called from syscall or from eBPF program */
667static int stack_map_delete_elem(struct bpf_map *map, void *key)
668{
669 struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);
670 struct stack_map_bucket *old_bucket;
671 u32 id = *(u32 *)key;
672
673 if (unlikely(id >= smap->n_buckets))
674 return -E2BIG;
675
676 old_bucket = xchg(&smap->buckets[id], NULL);
677 if (old_bucket) {
678 pcpu_freelist_push(&smap->freelist, &old_bucket->fnode);
679 return 0;
680 } else {
681 return -ENOENT;
682 }
683}
684
685/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
686static void stack_map_free(struct bpf_map *map)
687{
688 struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);
689
690 bpf_map_area_free(smap->elems);
691 pcpu_freelist_destroy(&smap->freelist);
692 bpf_map_area_free(smap);
693 put_callchain_buffers();
694}
695
696static int stack_trace_map_btf_id;
697const struct bpf_map_ops stack_trace_map_ops = {
698 .map_meta_equal = bpf_map_meta_equal,
699 .map_alloc = stack_map_alloc,
700 .map_free = stack_map_free,
701 .map_get_next_key = stack_map_get_next_key,
702 .map_lookup_elem = stack_map_lookup_elem,
703 .map_update_elem = stack_map_update_elem,
704 .map_delete_elem = stack_map_delete_elem,
705 .map_check_btf = map_check_no_btf,
706 .map_btf_name = "bpf_stack_map",
707 .map_btf_id = &stack_trace_map_btf_id,
708};
709
710static int __init stack_map_init(void)
711{
712 int cpu;
713 struct stack_map_irq_work *work;
714
715 for_each_possible_cpu(cpu) {
716 work = per_cpu_ptr(&up_read_work, cpu);
717 init_irq_work(&work->irq_work, do_up_read);
718 }
719 return 0;
720}
721subsys_initcall(stack_map_init);