projects/linux·blob v5.15-rc3 · refs

733 lines · 18.7 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(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(current->mm);
208 } else {
209 work->mm = current->mm;
210
211 /* The lock will be released once we're out of interrupt
212 * context. Tell lockdep that we've released it now so
213 * it doesn't complain that we forgot to release it.
214 */
215 rwsem_release(&current->mm->mmap_lock.dep_map, _RET_IP_);
216 irq_work_queue(&work->irq_work);
217 }
218}
219
220static struct perf_callchain_entry *
221get_callchain_entry_for_task(struct task_struct *task, u32 init_nr)
222{
223#ifdef CONFIG_STACKTRACE
224 struct perf_callchain_entry *entry;
225 int rctx;
226
227 entry = get_callchain_entry(&rctx);
228
229 if (!entry)
230 return NULL;
231
232 entry->nr = init_nr +
233 stack_trace_save_tsk(task, (unsigned long *)(entry->ip + init_nr),
234 sysctl_perf_event_max_stack - init_nr, 0);
235
236 /* stack_trace_save_tsk() works on unsigned long array, while
237 * perf_callchain_entry uses u64 array. For 32-bit systems, it is
238 * necessary to fix this mismatch.
239 */
240 if (__BITS_PER_LONG != 64) {
241 unsigned long *from = (unsigned long *) entry->ip;
242 u64 *to = entry->ip;
243 int i;
244
245 /* copy data from the end to avoid using extra buffer */
246 for (i = entry->nr - 1; i >= (int)init_nr; i--)
247 to[i] = (u64)(from[i]);
248 }
249
250 put_callchain_entry(rctx);
251
252 return entry;
253#else /* CONFIG_STACKTRACE */
254 return NULL;
255#endif
256}
257
258static long __bpf_get_stackid(struct bpf_map *map,
259 struct perf_callchain_entry *trace, u64 flags)
260{
261 struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);
262 struct stack_map_bucket *bucket, *new_bucket, *old_bucket;
263 u32 max_depth = map->value_size / stack_map_data_size(map);
264 /* stack_map_alloc() checks that max_depth <= sysctl_perf_event_max_stack */
265 u32 init_nr = sysctl_perf_event_max_stack - max_depth;
266 u32 skip = flags & BPF_F_SKIP_FIELD_MASK;
267 u32 hash, id, trace_nr, trace_len;
268 bool user = flags & BPF_F_USER_STACK;
269 u64 *ips;
270 bool hash_matches;
271
272 /* get_perf_callchain() guarantees that trace->nr >= init_nr
273 * and trace-nr <= sysctl_perf_event_max_stack, so trace_nr <= max_depth
274 */
275 trace_nr = trace->nr - init_nr;
276
277 if (trace_nr <= skip)
278 /* skipping more than usable stack trace */
279 return -EFAULT;
280
281 trace_nr -= skip;
282 trace_len = trace_nr * sizeof(u64);
283 ips = trace->ip + skip + init_nr;
284 hash = jhash2((u32 *)ips, trace_len / sizeof(u32), 0);
285 id = hash & (smap->n_buckets - 1);
286 bucket = READ_ONCE(smap->buckets[id]);
287
288 hash_matches = bucket && bucket->hash == hash;
289 /* fast cmp */
290 if (hash_matches && flags & BPF_F_FAST_STACK_CMP)
291 return id;
292
293 if (stack_map_use_build_id(map)) {
294 /* for build_id+offset, pop a bucket before slow cmp */
295 new_bucket = (struct stack_map_bucket *)
296 pcpu_freelist_pop(&smap->freelist);
297 if (unlikely(!new_bucket))
298 return -ENOMEM;
299 new_bucket->nr = trace_nr;
300 stack_map_get_build_id_offset(
301 (struct bpf_stack_build_id *)new_bucket->data,
302 ips, trace_nr, user);
303 trace_len = trace_nr * sizeof(struct bpf_stack_build_id);
304 if (hash_matches && bucket->nr == trace_nr &&
305 memcmp(bucket->data, new_bucket->data, trace_len) == 0) {
306 pcpu_freelist_push(&smap->freelist, &new_bucket->fnode);
307 return id;
308 }
309 if (bucket && !(flags & BPF_F_REUSE_STACKID)) {
310 pcpu_freelist_push(&smap->freelist, &new_bucket->fnode);
311 return -EEXIST;
312 }
313 } else {
314 if (hash_matches && bucket->nr == trace_nr &&
315 memcmp(bucket->data, ips, trace_len) == 0)
316 return id;
317 if (bucket && !(flags & BPF_F_REUSE_STACKID))
318 return -EEXIST;
319
320 new_bucket = (struct stack_map_bucket *)
321 pcpu_freelist_pop(&smap->freelist);
322 if (unlikely(!new_bucket))
323 return -ENOMEM;
324 memcpy(new_bucket->data, ips, trace_len);
325 }
326
327 new_bucket->hash = hash;
328 new_bucket->nr = trace_nr;
329
330 old_bucket = xchg(&smap->buckets[id], new_bucket);
331 if (old_bucket)
332 pcpu_freelist_push(&smap->freelist, &old_bucket->fnode);
333 return id;
334}
335
336BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map,
337 u64, flags)
338{
339 u32 max_depth = map->value_size / stack_map_data_size(map);
340 /* stack_map_alloc() checks that max_depth <= sysctl_perf_event_max_stack */
341 u32 init_nr = sysctl_perf_event_max_stack - max_depth;
342 bool user = flags & BPF_F_USER_STACK;
343 struct perf_callchain_entry *trace;
344 bool kernel = !user;
345
346 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
347 BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID)))
348 return -EINVAL;
349
350 trace = get_perf_callchain(regs, init_nr, kernel, user,
351 sysctl_perf_event_max_stack, false, false);
352
353 if (unlikely(!trace))
354 /* couldn't fetch the stack trace */
355 return -EFAULT;
356
357 return __bpf_get_stackid(map, trace, flags);
358}
359
360const struct bpf_func_proto bpf_get_stackid_proto = {
361 .func = bpf_get_stackid,
362 .gpl_only = true,
363 .ret_type = RET_INTEGER,
364 .arg1_type = ARG_PTR_TO_CTX,
365 .arg2_type = ARG_CONST_MAP_PTR,
366 .arg3_type = ARG_ANYTHING,
367};
368
369static __u64 count_kernel_ip(struct perf_callchain_entry *trace)
370{
371 __u64 nr_kernel = 0;
372
373 while (nr_kernel < trace->nr) {
374 if (trace->ip[nr_kernel] == PERF_CONTEXT_USER)
375 break;
376 nr_kernel++;
377 }
378 return nr_kernel;
379}
380
381BPF_CALL_3(bpf_get_stackid_pe, struct bpf_perf_event_data_kern *, ctx,
382 struct bpf_map *, map, u64, flags)
383{
384 struct perf_event *event = ctx->event;
385 struct perf_callchain_entry *trace;
386 bool kernel, user;
387 __u64 nr_kernel;
388 int ret;
389
390 /* perf_sample_data doesn't have callchain, use bpf_get_stackid */
391 if (!(event->attr.sample_type & __PERF_SAMPLE_CALLCHAIN_EARLY))
392 return bpf_get_stackid((unsigned long)(ctx->regs),
393 (unsigned long) map, flags, 0, 0);
394
395 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
396 BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID)))
397 return -EINVAL;
398
399 user = flags & BPF_F_USER_STACK;
400 kernel = !user;
401
402 trace = ctx->data->callchain;
403 if (unlikely(!trace))
404 return -EFAULT;
405
406 nr_kernel = count_kernel_ip(trace);
407
408 if (kernel) {
409 __u64 nr = trace->nr;
410
411 trace->nr = nr_kernel;
412 ret = __bpf_get_stackid(map, trace, flags);
413
414 /* restore nr */
415 trace->nr = nr;
416 } else { /* user */
417 u64 skip = flags & BPF_F_SKIP_FIELD_MASK;
418
419 skip += nr_kernel;
420 if (skip > BPF_F_SKIP_FIELD_MASK)
421 return -EFAULT;
422
423 flags = (flags & ~BPF_F_SKIP_FIELD_MASK) | skip;
424 ret = __bpf_get_stackid(map, trace, flags);
425 }
426 return ret;
427}
428
429const struct bpf_func_proto bpf_get_stackid_proto_pe = {
430 .func = bpf_get_stackid_pe,
431 .gpl_only = false,
432 .ret_type = RET_INTEGER,
433 .arg1_type = ARG_PTR_TO_CTX,
434 .arg2_type = ARG_CONST_MAP_PTR,
435 .arg3_type = ARG_ANYTHING,
436};
437
438static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task,
439 struct perf_callchain_entry *trace_in,
440 void *buf, u32 size, u64 flags)
441{
442 u32 init_nr, trace_nr, copy_len, elem_size, num_elem;
443 bool user_build_id = flags & BPF_F_USER_BUILD_ID;
444 u32 skip = flags & BPF_F_SKIP_FIELD_MASK;
445 bool user = flags & BPF_F_USER_STACK;
446 struct perf_callchain_entry *trace;
447 bool kernel = !user;
448 int err = -EINVAL;
449 u64 *ips;
450
451 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
452 BPF_F_USER_BUILD_ID)))
453 goto clear;
454 if (kernel && user_build_id)
455 goto clear;
456
457 elem_size = (user && user_build_id) ? sizeof(struct bpf_stack_build_id)
458 : sizeof(u64);
459 if (unlikely(size % elem_size))
460 goto clear;
461
462 /* cannot get valid user stack for task without user_mode regs */
463 if (task && user && !user_mode(regs))
464 goto err_fault;
465
466 num_elem = size / elem_size;
467 if (sysctl_perf_event_max_stack < num_elem)
468 init_nr = 0;
469 else
470 init_nr = sysctl_perf_event_max_stack - num_elem;
471
472 if (trace_in)
473 trace = trace_in;
474 else if (kernel && task)
475 trace = get_callchain_entry_for_task(task, init_nr);
476 else
477 trace = get_perf_callchain(regs, init_nr, kernel, user,
478 sysctl_perf_event_max_stack,
479 false, false);
480 if (unlikely(!trace))
481 goto err_fault;
482
483 trace_nr = trace->nr - init_nr;
484 if (trace_nr < skip)
485 goto err_fault;
486
487 trace_nr -= skip;
488 trace_nr = (trace_nr <= num_elem) ? trace_nr : num_elem;
489 copy_len = trace_nr * elem_size;
490 ips = trace->ip + skip + init_nr;
491 if (user && user_build_id)
492 stack_map_get_build_id_offset(buf, ips, trace_nr, user);
493 else
494 memcpy(buf, ips, copy_len);
495
496 if (size > copy_len)
497 memset(buf + copy_len, 0, size - copy_len);
498 return copy_len;
499
500err_fault:
501 err = -EFAULT;
502clear:
503 memset(buf, 0, size);
504 return err;
505}
506
507BPF_CALL_4(bpf_get_stack, struct pt_regs *, regs, void *, buf, u32, size,
508 u64, flags)
509{
510 return __bpf_get_stack(regs, NULL, NULL, buf, size, flags);
511}
512
513const struct bpf_func_proto bpf_get_stack_proto = {
514 .func = bpf_get_stack,
515 .gpl_only = true,
516 .ret_type = RET_INTEGER,
517 .arg1_type = ARG_PTR_TO_CTX,
518 .arg2_type = ARG_PTR_TO_UNINIT_MEM,
519 .arg3_type = ARG_CONST_SIZE_OR_ZERO,
520 .arg4_type = ARG_ANYTHING,
521};
522
523BPF_CALL_4(bpf_get_task_stack, struct task_struct *, task, void *, buf,
524 u32, size, u64, flags)
525{
526 struct pt_regs *regs;
527 long res;
528
529 if (!try_get_task_stack(task))
530 return -EFAULT;
531
532 regs = task_pt_regs(task);
533 res = __bpf_get_stack(regs, task, NULL, buf, size, flags);
534 put_task_stack(task);
535
536 return res;
537}
538
539const struct bpf_func_proto bpf_get_task_stack_proto = {
540 .func = bpf_get_task_stack,
541 .gpl_only = false,
542 .ret_type = RET_INTEGER,
543 .arg1_type = ARG_PTR_TO_BTF_ID,
544 .arg1_btf_id = &btf_task_struct_ids[0],
545 .arg2_type = ARG_PTR_TO_UNINIT_MEM,
546 .arg3_type = ARG_CONST_SIZE_OR_ZERO,
547 .arg4_type = ARG_ANYTHING,
548};
549
550BPF_CALL_4(bpf_get_stack_pe, struct bpf_perf_event_data_kern *, ctx,
551 void *, buf, u32, size, u64, flags)
552{
553 struct pt_regs *regs = (struct pt_regs *)(ctx->regs);
554 struct perf_event *event = ctx->event;
555 struct perf_callchain_entry *trace;
556 bool kernel, user;
557 int err = -EINVAL;
558 __u64 nr_kernel;
559
560 if (!(event->attr.sample_type & __PERF_SAMPLE_CALLCHAIN_EARLY))
561 return __bpf_get_stack(regs, NULL, NULL, buf, size, flags);
562
563 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
564 BPF_F_USER_BUILD_ID)))
565 goto clear;
566
567 user = flags & BPF_F_USER_STACK;
568 kernel = !user;
569
570 err = -EFAULT;
571 trace = ctx->data->callchain;
572 if (unlikely(!trace))
573 goto clear;
574
575 nr_kernel = count_kernel_ip(trace);
576
577 if (kernel) {
578 __u64 nr = trace->nr;
579
580 trace->nr = nr_kernel;
581 err = __bpf_get_stack(regs, NULL, trace, buf, size, flags);
582
583 /* restore nr */
584 trace->nr = nr;
585 } else { /* user */
586 u64 skip = flags & BPF_F_SKIP_FIELD_MASK;
587
588 skip += nr_kernel;
589 if (skip > BPF_F_SKIP_FIELD_MASK)
590 goto clear;
591
592 flags = (flags & ~BPF_F_SKIP_FIELD_MASK) | skip;
593 err = __bpf_get_stack(regs, NULL, trace, buf, size, flags);
594 }
595 return err;
596
597clear:
598 memset(buf, 0, size);
599 return err;
600
601}
602
603const struct bpf_func_proto bpf_get_stack_proto_pe = {
604 .func = bpf_get_stack_pe,
605 .gpl_only = true,
606 .ret_type = RET_INTEGER,
607 .arg1_type = ARG_PTR_TO_CTX,
608 .arg2_type = ARG_PTR_TO_UNINIT_MEM,
609 .arg3_type = ARG_CONST_SIZE_OR_ZERO,
610 .arg4_type = ARG_ANYTHING,
611};
612
613/* Called from eBPF program */
614static void *stack_map_lookup_elem(struct bpf_map *map, void *key)
615{
616 return ERR_PTR(-EOPNOTSUPP);
617}
618
619/* Called from syscall */
620int bpf_stackmap_copy(struct bpf_map *map, void *key, void *value)
621{
622 struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);
623 struct stack_map_bucket *bucket, *old_bucket;
624 u32 id = *(u32 *)key, trace_len;
625
626 if (unlikely(id >= smap->n_buckets))
627 return -ENOENT;
628
629 bucket = xchg(&smap->buckets[id], NULL);
630 if (!bucket)
631 return -ENOENT;
632
633 trace_len = bucket->nr * stack_map_data_size(map);
634 memcpy(value, bucket->data, trace_len);
635 memset(value + trace_len, 0, map->value_size - trace_len);
636
637 old_bucket = xchg(&smap->buckets[id], bucket);
638 if (old_bucket)
639 pcpu_freelist_push(&smap->freelist, &old_bucket->fnode);
640 return 0;
641}
642
643static int stack_map_get_next_key(struct bpf_map *map, void *key,
644 void *next_key)
645{
646 struct bpf_stack_map *smap = container_of(map,
647 struct bpf_stack_map, map);
648 u32 id;
649
650 WARN_ON_ONCE(!rcu_read_lock_held());
651
652 if (!key) {
653 id = 0;
654 } else {
655 id = *(u32 *)key;
656 if (id >= smap->n_buckets || !smap->buckets[id])
657 id = 0;
658 else
659 id++;
660 }
661
662 while (id < smap->n_buckets && !smap->buckets[id])
663 id++;
664
665 if (id >= smap->n_buckets)
666 return -ENOENT;
667
668 *(u32 *)next_key = id;
669 return 0;
670}
671
672static int stack_map_update_elem(struct bpf_map *map, void *key, void *value,
673 u64 map_flags)
674{
675 return -EINVAL;
676}
677
678/* Called from syscall or from eBPF program */
679static int stack_map_delete_elem(struct bpf_map *map, void *key)
680{
681 struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);
682 struct stack_map_bucket *old_bucket;
683 u32 id = *(u32 *)key;
684
685 if (unlikely(id >= smap->n_buckets))
686 return -E2BIG;
687
688 old_bucket = xchg(&smap->buckets[id], NULL);
689 if (old_bucket) {
690 pcpu_freelist_push(&smap->freelist, &old_bucket->fnode);
691 return 0;
692 } else {
693 return -ENOENT;
694 }
695}
696
697/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
698static void stack_map_free(struct bpf_map *map)
699{
700 struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);
701
702 bpf_map_area_free(smap->elems);
703 pcpu_freelist_destroy(&smap->freelist);
704 bpf_map_area_free(smap);
705 put_callchain_buffers();
706}
707
708static int stack_trace_map_btf_id;
709const struct bpf_map_ops stack_trace_map_ops = {
710 .map_meta_equal = bpf_map_meta_equal,
711 .map_alloc = stack_map_alloc,
712 .map_free = stack_map_free,
713 .map_get_next_key = stack_map_get_next_key,
714 .map_lookup_elem = stack_map_lookup_elem,
715 .map_update_elem = stack_map_update_elem,
716 .map_delete_elem = stack_map_delete_elem,
717 .map_check_btf = map_check_no_btf,
718 .map_btf_name = "bpf_stack_map",
719 .map_btf_id = &stack_trace_map_btf_id,
720};
721
722static int __init stack_map_init(void)
723{
724 int cpu;
725 struct stack_map_irq_work *work;
726
727 for_each_possible_cpu(cpu) {
728 work = per_cpu_ptr(&up_read_work, cpu);
729 init_irq_work(&work->irq_work, do_up_read);
730 }
731 return 0;
732}
733subsys_initcall(stack_map_init);