1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Copyright (c) 2016 Facebook
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/elf.h>
11 #include <linux/pagemap.h>
12 #include <linux/irq_work.h>
13 #include <linux/btf_ids.h>
14 #include "percpu_freelist.h"
16 #define STACK_CREATE_FLAG_MASK \
17 (BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY | \
20 struct stack_map_bucket {
21 struct pcpu_freelist_node fnode;
27 struct bpf_stack_map {
30 struct pcpu_freelist freelist;
32 struct stack_map_bucket *buckets[];
35 /* irq_work to run up_read() for build_id lookup in nmi context */
36 struct stack_map_irq_work {
37 struct irq_work irq_work;
41 static void do_up_read(struct irq_work *entry)
43 struct stack_map_irq_work *work;
45 if (WARN_ON_ONCE(IS_ENABLED(CONFIG_PREEMPT_RT)))
48 work = container_of(entry, struct stack_map_irq_work, irq_work);
49 mmap_read_unlock_non_owner(work->mm);
52 static DEFINE_PER_CPU(struct stack_map_irq_work, up_read_work);
54 static inline bool stack_map_use_build_id(struct bpf_map *map)
56 return (map->map_flags & BPF_F_STACK_BUILD_ID);
59 static inline int stack_map_data_size(struct bpf_map *map)
61 return stack_map_use_build_id(map) ?
62 sizeof(struct bpf_stack_build_id) : sizeof(u64);
65 static int prealloc_elems_and_freelist(struct bpf_stack_map *smap)
67 u32 elem_size = sizeof(struct stack_map_bucket) + smap->map.value_size;
70 smap->elems = bpf_map_area_alloc(elem_size * smap->map.max_entries,
75 err = pcpu_freelist_init(&smap->freelist);
79 pcpu_freelist_populate(&smap->freelist, smap->elems, elem_size,
80 smap->map.max_entries);
84 bpf_map_area_free(smap->elems);
88 /* Called from syscall */
89 static struct bpf_map *stack_map_alloc(union bpf_attr *attr)
91 u32 value_size = attr->value_size;
92 struct bpf_stack_map *smap;
97 return ERR_PTR(-EPERM);
99 if (attr->map_flags & ~STACK_CREATE_FLAG_MASK)
100 return ERR_PTR(-EINVAL);
102 /* check sanity of attributes */
103 if (attr->max_entries == 0 || attr->key_size != 4 ||
104 value_size < 8 || value_size % 8)
105 return ERR_PTR(-EINVAL);
107 BUILD_BUG_ON(sizeof(struct bpf_stack_build_id) % sizeof(u64));
108 if (attr->map_flags & BPF_F_STACK_BUILD_ID) {
109 if (value_size % sizeof(struct bpf_stack_build_id) ||
110 value_size / sizeof(struct bpf_stack_build_id)
111 > sysctl_perf_event_max_stack)
112 return ERR_PTR(-EINVAL);
113 } else if (value_size / 8 > sysctl_perf_event_max_stack)
114 return ERR_PTR(-EINVAL);
116 /* hash table size must be power of 2 */
117 n_buckets = roundup_pow_of_two(attr->max_entries);
119 cost = n_buckets * sizeof(struct stack_map_bucket *) + sizeof(*smap);
120 cost += n_buckets * (value_size + sizeof(struct stack_map_bucket));
121 smap = bpf_map_area_alloc(cost, bpf_map_attr_numa_node(attr));
123 return ERR_PTR(-ENOMEM);
125 bpf_map_init_from_attr(&smap->map, attr);
126 smap->map.value_size = value_size;
127 smap->n_buckets = n_buckets;
129 err = get_callchain_buffers(sysctl_perf_event_max_stack);
133 err = prealloc_elems_and_freelist(smap);
140 put_callchain_buffers();
142 bpf_map_area_free(smap);
146 #define BPF_BUILD_ID 3
148 * Parse build id from the note segment. This logic can be shared between
149 * 32-bit and 64-bit system, because Elf32_Nhdr and Elf64_Nhdr are
152 static inline int stack_map_parse_build_id(void *page_addr,
153 unsigned char *build_id,
155 Elf32_Word note_size)
157 Elf32_Word note_offs = 0, new_offs;
159 /* check for overflow */
160 if (note_start < page_addr || note_start + note_size < note_start)
163 /* only supports note that fits in the first page */
164 if (note_start + note_size > page_addr + PAGE_SIZE)
167 while (note_offs + sizeof(Elf32_Nhdr) < note_size) {
168 Elf32_Nhdr *nhdr = (Elf32_Nhdr *)(note_start + note_offs);
170 if (nhdr->n_type == BPF_BUILD_ID &&
171 nhdr->n_namesz == sizeof("GNU") &&
172 nhdr->n_descsz > 0 &&
173 nhdr->n_descsz <= BPF_BUILD_ID_SIZE) {
175 note_start + note_offs +
176 ALIGN(sizeof("GNU"), 4) + sizeof(Elf32_Nhdr),
178 memset(build_id + nhdr->n_descsz, 0,
179 BPF_BUILD_ID_SIZE - nhdr->n_descsz);
182 new_offs = note_offs + sizeof(Elf32_Nhdr) +
183 ALIGN(nhdr->n_namesz, 4) + ALIGN(nhdr->n_descsz, 4);
184 if (new_offs <= note_offs) /* overflow */
186 note_offs = new_offs;
191 /* Parse build ID from 32-bit ELF */
192 static int stack_map_get_build_id_32(void *page_addr,
193 unsigned char *build_id)
195 Elf32_Ehdr *ehdr = (Elf32_Ehdr *)page_addr;
199 /* only supports phdr that fits in one page */
201 (PAGE_SIZE - sizeof(Elf32_Ehdr)) / sizeof(Elf32_Phdr))
204 phdr = (Elf32_Phdr *)(page_addr + sizeof(Elf32_Ehdr));
206 for (i = 0; i < ehdr->e_phnum; ++i) {
207 if (phdr[i].p_type == PT_NOTE &&
208 !stack_map_parse_build_id(page_addr, build_id,
209 page_addr + phdr[i].p_offset,
216 /* Parse build ID from 64-bit ELF */
217 static int stack_map_get_build_id_64(void *page_addr,
218 unsigned char *build_id)
220 Elf64_Ehdr *ehdr = (Elf64_Ehdr *)page_addr;
224 /* only supports phdr that fits in one page */
226 (PAGE_SIZE - sizeof(Elf64_Ehdr)) / sizeof(Elf64_Phdr))
229 phdr = (Elf64_Phdr *)(page_addr + sizeof(Elf64_Ehdr));
231 for (i = 0; i < ehdr->e_phnum; ++i) {
232 if (phdr[i].p_type == PT_NOTE &&
233 !stack_map_parse_build_id(page_addr, build_id,
234 page_addr + phdr[i].p_offset,
241 /* Parse build ID of ELF file mapped to vma */
242 static int stack_map_get_build_id(struct vm_area_struct *vma,
243 unsigned char *build_id)
250 /* only works for page backed storage */
254 page = find_get_page(vma->vm_file->f_mapping, 0);
256 return -EFAULT; /* page not mapped */
259 page_addr = kmap_atomic(page);
260 ehdr = (Elf32_Ehdr *)page_addr;
262 /* compare magic x7f "ELF" */
263 if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0)
266 /* only support executable file and shared object file */
267 if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN)
270 if (ehdr->e_ident[EI_CLASS] == ELFCLASS32)
271 ret = stack_map_get_build_id_32(page_addr, build_id);
272 else if (ehdr->e_ident[EI_CLASS] == ELFCLASS64)
273 ret = stack_map_get_build_id_64(page_addr, build_id);
275 kunmap_atomic(page_addr);
280 static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs,
281 u64 *ips, u32 trace_nr, bool user)
284 struct vm_area_struct *vma;
285 bool irq_work_busy = false;
286 struct stack_map_irq_work *work = NULL;
288 if (irqs_disabled()) {
289 if (!IS_ENABLED(CONFIG_PREEMPT_RT)) {
290 work = this_cpu_ptr(&up_read_work);
291 if (irq_work_is_busy(&work->irq_work)) {
292 /* cannot queue more up_read, fallback */
293 irq_work_busy = true;
297 * PREEMPT_RT does not allow to trylock mmap sem in
298 * interrupt disabled context. Force the fallback code.
300 irq_work_busy = true;
305 * We cannot do up_read() when the irq is disabled, because of
306 * risk to deadlock with rq_lock. To do build_id lookup when the
307 * irqs are disabled, we need to run up_read() in irq_work. We use
308 * a percpu variable to do the irq_work. If the irq_work is
309 * already used by another lookup, we fall back to report ips.
311 * Same fallback is used for kernel stack (!user) on a stackmap
314 if (!user || !current || !current->mm || irq_work_busy ||
315 !mmap_read_trylock_non_owner(current->mm)) {
316 /* cannot access current->mm, fall back to ips */
317 for (i = 0; i < trace_nr; i++) {
318 id_offs[i].status = BPF_STACK_BUILD_ID_IP;
319 id_offs[i].ip = ips[i];
320 memset(id_offs[i].build_id, 0, BPF_BUILD_ID_SIZE);
325 for (i = 0; i < trace_nr; i++) {
326 vma = find_vma(current->mm, ips[i]);
327 if (!vma || stack_map_get_build_id(vma, id_offs[i].build_id)) {
328 /* per entry fall back to ips */
329 id_offs[i].status = BPF_STACK_BUILD_ID_IP;
330 id_offs[i].ip = ips[i];
331 memset(id_offs[i].build_id, 0, BPF_BUILD_ID_SIZE);
334 id_offs[i].offset = (vma->vm_pgoff << PAGE_SHIFT) + ips[i]
336 id_offs[i].status = BPF_STACK_BUILD_ID_VALID;
340 mmap_read_unlock_non_owner(current->mm);
342 work->mm = current->mm;
343 irq_work_queue(&work->irq_work);
347 static struct perf_callchain_entry *
348 get_callchain_entry_for_task(struct task_struct *task, u32 init_nr)
350 #ifdef CONFIG_STACKTRACE
351 struct perf_callchain_entry *entry;
354 entry = get_callchain_entry(&rctx);
359 entry->nr = init_nr +
360 stack_trace_save_tsk(task, (unsigned long *)(entry->ip + init_nr),
361 sysctl_perf_event_max_stack - init_nr, 0);
363 /* stack_trace_save_tsk() works on unsigned long array, while
364 * perf_callchain_entry uses u64 array. For 32-bit systems, it is
365 * necessary to fix this mismatch.
367 if (__BITS_PER_LONG != 64) {
368 unsigned long *from = (unsigned long *) entry->ip;
372 /* copy data from the end to avoid using extra buffer */
373 for (i = entry->nr - 1; i >= (int)init_nr; i--)
374 to[i] = (u64)(from[i]);
377 put_callchain_entry(rctx);
380 #else /* CONFIG_STACKTRACE */
385 static long __bpf_get_stackid(struct bpf_map *map,
386 struct perf_callchain_entry *trace, u64 flags)
388 struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);
389 struct stack_map_bucket *bucket, *new_bucket, *old_bucket;
390 u32 max_depth = map->value_size / stack_map_data_size(map);
391 /* stack_map_alloc() checks that max_depth <= sysctl_perf_event_max_stack */
392 u32 init_nr = sysctl_perf_event_max_stack - max_depth;
393 u32 skip = flags & BPF_F_SKIP_FIELD_MASK;
394 u32 hash, id, trace_nr, trace_len;
395 bool user = flags & BPF_F_USER_STACK;
399 /* get_perf_callchain() guarantees that trace->nr >= init_nr
400 * and trace-nr <= sysctl_perf_event_max_stack, so trace_nr <= max_depth
402 trace_nr = trace->nr - init_nr;
404 if (trace_nr <= skip)
405 /* skipping more than usable stack trace */
409 trace_len = trace_nr * sizeof(u64);
410 ips = trace->ip + skip + init_nr;
411 hash = jhash2((u32 *)ips, trace_len / sizeof(u32), 0);
412 id = hash & (smap->n_buckets - 1);
413 bucket = READ_ONCE(smap->buckets[id]);
415 hash_matches = bucket && bucket->hash == hash;
417 if (hash_matches && flags & BPF_F_FAST_STACK_CMP)
420 if (stack_map_use_build_id(map)) {
421 /* for build_id+offset, pop a bucket before slow cmp */
422 new_bucket = (struct stack_map_bucket *)
423 pcpu_freelist_pop(&smap->freelist);
424 if (unlikely(!new_bucket))
426 new_bucket->nr = trace_nr;
427 stack_map_get_build_id_offset(
428 (struct bpf_stack_build_id *)new_bucket->data,
429 ips, trace_nr, user);
430 trace_len = trace_nr * sizeof(struct bpf_stack_build_id);
431 if (hash_matches && bucket->nr == trace_nr &&
432 memcmp(bucket->data, new_bucket->data, trace_len) == 0) {
433 pcpu_freelist_push(&smap->freelist, &new_bucket->fnode);
436 if (bucket && !(flags & BPF_F_REUSE_STACKID)) {
437 pcpu_freelist_push(&smap->freelist, &new_bucket->fnode);
441 if (hash_matches && bucket->nr == trace_nr &&
442 memcmp(bucket->data, ips, trace_len) == 0)
444 if (bucket && !(flags & BPF_F_REUSE_STACKID))
447 new_bucket = (struct stack_map_bucket *)
448 pcpu_freelist_pop(&smap->freelist);
449 if (unlikely(!new_bucket))
451 memcpy(new_bucket->data, ips, trace_len);
454 new_bucket->hash = hash;
455 new_bucket->nr = trace_nr;
457 old_bucket = xchg(&smap->buckets[id], new_bucket);
459 pcpu_freelist_push(&smap->freelist, &old_bucket->fnode);
463 BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map,
466 u32 max_depth = map->value_size / stack_map_data_size(map);
467 /* stack_map_alloc() checks that max_depth <= sysctl_perf_event_max_stack */
468 u32 init_nr = sysctl_perf_event_max_stack - max_depth;
469 bool user = flags & BPF_F_USER_STACK;
470 struct perf_callchain_entry *trace;
473 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
474 BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID)))
477 trace = get_perf_callchain(regs, init_nr, kernel, user,
478 sysctl_perf_event_max_stack, false, false);
480 if (unlikely(!trace))
481 /* couldn't fetch the stack trace */
484 return __bpf_get_stackid(map, trace, flags);
487 const struct bpf_func_proto bpf_get_stackid_proto = {
488 .func = bpf_get_stackid,
490 .ret_type = RET_INTEGER,
491 .arg1_type = ARG_PTR_TO_CTX,
492 .arg2_type = ARG_CONST_MAP_PTR,
493 .arg3_type = ARG_ANYTHING,
496 static __u64 count_kernel_ip(struct perf_callchain_entry *trace)
500 while (nr_kernel < trace->nr) {
501 if (trace->ip[nr_kernel] == PERF_CONTEXT_USER)
508 BPF_CALL_3(bpf_get_stackid_pe, struct bpf_perf_event_data_kern *, ctx,
509 struct bpf_map *, map, u64, flags)
511 struct perf_event *event = ctx->event;
512 struct perf_callchain_entry *trace;
517 /* perf_sample_data doesn't have callchain, use bpf_get_stackid */
518 if (!(event->attr.sample_type & __PERF_SAMPLE_CALLCHAIN_EARLY))
519 return bpf_get_stackid((unsigned long)(ctx->regs),
520 (unsigned long) map, flags, 0, 0);
522 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
523 BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID)))
526 user = flags & BPF_F_USER_STACK;
529 trace = ctx->data->callchain;
530 if (unlikely(!trace))
533 nr_kernel = count_kernel_ip(trace);
536 __u64 nr = trace->nr;
538 trace->nr = nr_kernel;
539 ret = __bpf_get_stackid(map, trace, flags);
544 u64 skip = flags & BPF_F_SKIP_FIELD_MASK;
547 if (skip > BPF_F_SKIP_FIELD_MASK)
550 flags = (flags & ~BPF_F_SKIP_FIELD_MASK) | skip;
551 ret = __bpf_get_stackid(map, trace, flags);
556 const struct bpf_func_proto bpf_get_stackid_proto_pe = {
557 .func = bpf_get_stackid_pe,
559 .ret_type = RET_INTEGER,
560 .arg1_type = ARG_PTR_TO_CTX,
561 .arg2_type = ARG_CONST_MAP_PTR,
562 .arg3_type = ARG_ANYTHING,
565 static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task,
566 struct perf_callchain_entry *trace_in,
567 void *buf, u32 size, u64 flags)
569 u32 init_nr, trace_nr, copy_len, elem_size, num_elem;
570 bool user_build_id = flags & BPF_F_USER_BUILD_ID;
571 u32 skip = flags & BPF_F_SKIP_FIELD_MASK;
572 bool user = flags & BPF_F_USER_STACK;
573 struct perf_callchain_entry *trace;
578 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
579 BPF_F_USER_BUILD_ID)))
581 if (kernel && user_build_id)
584 elem_size = (user && user_build_id) ? sizeof(struct bpf_stack_build_id)
586 if (unlikely(size % elem_size))
589 /* cannot get valid user stack for task without user_mode regs */
590 if (task && user && !user_mode(regs))
593 num_elem = size / elem_size;
594 if (sysctl_perf_event_max_stack < num_elem)
597 init_nr = sysctl_perf_event_max_stack - num_elem;
601 else if (kernel && task)
602 trace = get_callchain_entry_for_task(task, init_nr);
604 trace = get_perf_callchain(regs, init_nr, kernel, user,
605 sysctl_perf_event_max_stack,
607 if (unlikely(!trace))
610 trace_nr = trace->nr - init_nr;
615 trace_nr = (trace_nr <= num_elem) ? trace_nr : num_elem;
616 copy_len = trace_nr * elem_size;
617 ips = trace->ip + skip + init_nr;
618 if (user && user_build_id)
619 stack_map_get_build_id_offset(buf, ips, trace_nr, user);
621 memcpy(buf, ips, copy_len);
624 memset(buf + copy_len, 0, size - copy_len);
630 memset(buf, 0, size);
634 BPF_CALL_4(bpf_get_stack, struct pt_regs *, regs, void *, buf, u32, size,
637 return __bpf_get_stack(regs, NULL, NULL, buf, size, flags);
640 const struct bpf_func_proto bpf_get_stack_proto = {
641 .func = bpf_get_stack,
643 .ret_type = RET_INTEGER,
644 .arg1_type = ARG_PTR_TO_CTX,
645 .arg2_type = ARG_PTR_TO_UNINIT_MEM,
646 .arg3_type = ARG_CONST_SIZE_OR_ZERO,
647 .arg4_type = ARG_ANYTHING,
650 BPF_CALL_4(bpf_get_task_stack, struct task_struct *, task, void *, buf,
651 u32, size, u64, flags)
653 struct pt_regs *regs = task_pt_regs(task);
655 return __bpf_get_stack(regs, task, NULL, buf, size, flags);
658 BTF_ID_LIST_SINGLE(bpf_get_task_stack_btf_ids, struct, task_struct)
660 const struct bpf_func_proto bpf_get_task_stack_proto = {
661 .func = bpf_get_task_stack,
663 .ret_type = RET_INTEGER,
664 .arg1_type = ARG_PTR_TO_BTF_ID,
665 .arg1_btf_id = &bpf_get_task_stack_btf_ids[0],
666 .arg2_type = ARG_PTR_TO_UNINIT_MEM,
667 .arg3_type = ARG_CONST_SIZE_OR_ZERO,
668 .arg4_type = ARG_ANYTHING,
671 BPF_CALL_4(bpf_get_stack_pe, struct bpf_perf_event_data_kern *, ctx,
672 void *, buf, u32, size, u64, flags)
674 struct pt_regs *regs = (struct pt_regs *)(ctx->regs);
675 struct perf_event *event = ctx->event;
676 struct perf_callchain_entry *trace;
681 if (!(event->attr.sample_type & __PERF_SAMPLE_CALLCHAIN_EARLY))
682 return __bpf_get_stack(regs, NULL, NULL, buf, size, flags);
684 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
685 BPF_F_USER_BUILD_ID)))
688 user = flags & BPF_F_USER_STACK;
692 trace = ctx->data->callchain;
693 if (unlikely(!trace))
696 nr_kernel = count_kernel_ip(trace);
699 __u64 nr = trace->nr;
701 trace->nr = nr_kernel;
702 err = __bpf_get_stack(regs, NULL, trace, buf, size, flags);
707 u64 skip = flags & BPF_F_SKIP_FIELD_MASK;
710 if (skip > BPF_F_SKIP_FIELD_MASK)
713 flags = (flags & ~BPF_F_SKIP_FIELD_MASK) | skip;
714 err = __bpf_get_stack(regs, NULL, trace, buf, size, flags);
719 memset(buf, 0, size);
724 const struct bpf_func_proto bpf_get_stack_proto_pe = {
725 .func = bpf_get_stack_pe,
727 .ret_type = RET_INTEGER,
728 .arg1_type = ARG_PTR_TO_CTX,
729 .arg2_type = ARG_PTR_TO_UNINIT_MEM,
730 .arg3_type = ARG_CONST_SIZE_OR_ZERO,
731 .arg4_type = ARG_ANYTHING,
734 /* Called from eBPF program */
735 static void *stack_map_lookup_elem(struct bpf_map *map, void *key)
737 return ERR_PTR(-EOPNOTSUPP);
740 /* Called from syscall */
741 int bpf_stackmap_copy(struct bpf_map *map, void *key, void *value)
743 struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);
744 struct stack_map_bucket *bucket, *old_bucket;
745 u32 id = *(u32 *)key, trace_len;
747 if (unlikely(id >= smap->n_buckets))
750 bucket = xchg(&smap->buckets[id], NULL);
754 trace_len = bucket->nr * stack_map_data_size(map);
755 memcpy(value, bucket->data, trace_len);
756 memset(value + trace_len, 0, map->value_size - trace_len);
758 old_bucket = xchg(&smap->buckets[id], bucket);
760 pcpu_freelist_push(&smap->freelist, &old_bucket->fnode);
764 static int stack_map_get_next_key(struct bpf_map *map, void *key,
767 struct bpf_stack_map *smap = container_of(map,
768 struct bpf_stack_map, map);
771 WARN_ON_ONCE(!rcu_read_lock_held());
777 if (id >= smap->n_buckets || !smap->buckets[id])
783 while (id < smap->n_buckets && !smap->buckets[id])
786 if (id >= smap->n_buckets)
789 *(u32 *)next_key = id;
793 static int stack_map_update_elem(struct bpf_map *map, void *key, void *value,
799 /* Called from syscall or from eBPF program */
800 static int stack_map_delete_elem(struct bpf_map *map, void *key)
802 struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);
803 struct stack_map_bucket *old_bucket;
804 u32 id = *(u32 *)key;
806 if (unlikely(id >= smap->n_buckets))
809 old_bucket = xchg(&smap->buckets[id], NULL);
811 pcpu_freelist_push(&smap->freelist, &old_bucket->fnode);
818 /* Called when map->refcnt goes to zero, either from workqueue or from syscall */
819 static void stack_map_free(struct bpf_map *map)
821 struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);
823 bpf_map_area_free(smap->elems);
824 pcpu_freelist_destroy(&smap->freelist);
825 bpf_map_area_free(smap);
826 put_callchain_buffers();
829 static int stack_trace_map_btf_id;
830 const struct bpf_map_ops stack_trace_map_ops = {
831 .map_meta_equal = bpf_map_meta_equal,
832 .map_alloc = stack_map_alloc,
833 .map_free = stack_map_free,
834 .map_get_next_key = stack_map_get_next_key,
835 .map_lookup_elem = stack_map_lookup_elem,
836 .map_update_elem = stack_map_update_elem,
837 .map_delete_elem = stack_map_delete_elem,
838 .map_check_btf = map_check_no_btf,
839 .map_btf_name = "bpf_stack_map",
840 .map_btf_id = &stack_trace_map_btf_id,
843 static int __init stack_map_init(void)
846 struct stack_map_irq_work *work;
848 for_each_possible_cpu(cpu) {
849 work = per_cpu_ptr(&up_read_work, cpu);
850 init_irq_work(&work->irq_work, do_up_read);
854 subsys_initcall(stack_map_init);