projects/linux·blob v5.11-rc6 · refs

854 lines · 21.9 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/elf.h>
11#include <linux/pagemap.h>
12#include <linux/irq_work.h>
13#include <linux/btf_ids.h>
14#include "percpu_freelist.h"
15
16#define STACK_CREATE_FLAG_MASK \
17 (BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY | \
18 BPF_F_STACK_BUILD_ID)
19
20struct stack_map_bucket {
21 struct pcpu_freelist_node fnode;
22 u32 hash;
23 u32 nr;
24 u64 data[];
25};
26
27struct bpf_stack_map {
28 struct bpf_map map;
29 void *elems;
30 struct pcpu_freelist freelist;
31 u32 n_buckets;
32 struct stack_map_bucket *buckets[];
33};
34
35/* irq_work to run up_read() for build_id lookup in nmi context */
36struct stack_map_irq_work {
37 struct irq_work irq_work;
38 struct mm_struct *mm;
39};
40
41static void do_up_read(struct irq_work *entry)
42{
43 struct stack_map_irq_work *work;
44
45 if (WARN_ON_ONCE(IS_ENABLED(CONFIG_PREEMPT_RT)))
46 return;
47
48 work = container_of(entry, struct stack_map_irq_work, irq_work);
49 mmap_read_unlock_non_owner(work->mm);
50}
51
52static DEFINE_PER_CPU(struct stack_map_irq_work, up_read_work);
53
54static inline bool stack_map_use_build_id(struct bpf_map *map)
55{
56 return (map->map_flags & BPF_F_STACK_BUILD_ID);
57}
58
59static inline int stack_map_data_size(struct bpf_map *map)
60{
61 return stack_map_use_build_id(map) ?
62 sizeof(struct bpf_stack_build_id) : sizeof(u64);
63}
64
65static int prealloc_elems_and_freelist(struct bpf_stack_map *smap)
66{
67 u32 elem_size = sizeof(struct stack_map_bucket) + smap->map.value_size;
68 int err;
69
70 smap->elems = bpf_map_area_alloc(elem_size * smap->map.max_entries,
71 smap->map.numa_node);
72 if (!smap->elems)
73 return -ENOMEM;
74
75 err = pcpu_freelist_init(&smap->freelist);
76 if (err)
77 goto free_elems;
78
79 pcpu_freelist_populate(&smap->freelist, smap->elems, elem_size,
80 smap->map.max_entries);
81 return 0;
82
83free_elems:
84 bpf_map_area_free(smap->elems);
85 return err;
86}
87
88/* Called from syscall */
89static struct bpf_map *stack_map_alloc(union bpf_attr *attr)
90{
91 u32 value_size = attr->value_size;
92 struct bpf_stack_map *smap;
93 u64 cost, n_buckets;
94 int err;
95
96 if (!bpf_capable())
97 return ERR_PTR(-EPERM);
98
99 if (attr->map_flags & ~STACK_CREATE_FLAG_MASK)
100 return ERR_PTR(-EINVAL);
101
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);
106
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);
115
116 /* hash table size must be power of 2 */
117 n_buckets = roundup_pow_of_two(attr->max_entries);
118
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));
122 if (!smap)
123 return ERR_PTR(-ENOMEM);
124
125 bpf_map_init_from_attr(&smap->map, attr);
126 smap->map.value_size = value_size;
127 smap->n_buckets = n_buckets;
128
129 err = get_callchain_buffers(sysctl_perf_event_max_stack);
130 if (err)
131 goto free_smap;
132
133 err = prealloc_elems_and_freelist(smap);
134 if (err)
135 goto put_buffers;
136
137 return &smap->map;
138
139put_buffers:
140 put_callchain_buffers();
141free_smap:
142 bpf_map_area_free(smap);
143 return ERR_PTR(err);
144}
145
146#define BPF_BUILD_ID 3
147/*
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
150 * identical.
151 */
152static inline int stack_map_parse_build_id(void *page_addr,
153 unsigned char *build_id,
154 void *note_start,
155 Elf32_Word note_size)
156{
157 Elf32_Word note_offs = 0, new_offs;
158
159 /* check for overflow */
160 if (note_start < page_addr || note_start + note_size < note_start)
161 return -EINVAL;
162
163 /* only supports note that fits in the first page */
164 if (note_start + note_size > page_addr + PAGE_SIZE)
165 return -EINVAL;
166
167 while (note_offs + sizeof(Elf32_Nhdr) < note_size) {
168 Elf32_Nhdr *nhdr = (Elf32_Nhdr *)(note_start + note_offs);
169
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) {
174 memcpy(build_id,
175 note_start + note_offs +
176 ALIGN(sizeof("GNU"), 4) + sizeof(Elf32_Nhdr),
177 nhdr->n_descsz);
178 memset(build_id + nhdr->n_descsz, 0,
179 BPF_BUILD_ID_SIZE - nhdr->n_descsz);
180 return 0;
181 }
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 */
185 break;
186 note_offs = new_offs;
187 }
188 return -EINVAL;
189}
190
191/* Parse build ID from 32-bit ELF */
192static int stack_map_get_build_id_32(void *page_addr,
193 unsigned char *build_id)
194{
195 Elf32_Ehdr *ehdr = (Elf32_Ehdr *)page_addr;
196 Elf32_Phdr *phdr;
197 int i;
198
199 /* only supports phdr that fits in one page */
200 if (ehdr->e_phnum >
201 (PAGE_SIZE - sizeof(Elf32_Ehdr)) / sizeof(Elf32_Phdr))
202 return -EINVAL;
203
204 phdr = (Elf32_Phdr *)(page_addr + sizeof(Elf32_Ehdr));
205
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,
210 phdr[i].p_filesz))
211 return 0;
212 }
213 return -EINVAL;
214}
215
216/* Parse build ID from 64-bit ELF */
217static int stack_map_get_build_id_64(void *page_addr,
218 unsigned char *build_id)
219{
220 Elf64_Ehdr *ehdr = (Elf64_Ehdr *)page_addr;
221 Elf64_Phdr *phdr;
222 int i;
223
224 /* only supports phdr that fits in one page */
225 if (ehdr->e_phnum >
226 (PAGE_SIZE - sizeof(Elf64_Ehdr)) / sizeof(Elf64_Phdr))
227 return -EINVAL;
228
229 phdr = (Elf64_Phdr *)(page_addr + sizeof(Elf64_Ehdr));
230
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,
235 phdr[i].p_filesz))
236 return 0;
237 }
238 return -EINVAL;
239}
240
241/* Parse build ID of ELF file mapped to vma */
242static int stack_map_get_build_id(struct vm_area_struct *vma,
243 unsigned char *build_id)
244{
245 Elf32_Ehdr *ehdr;
246 struct page *page;
247 void *page_addr;
248 int ret;
249
250 /* only works for page backed storage */
251 if (!vma->vm_file)
252 return -EINVAL;
253
254 page = find_get_page(vma->vm_file->f_mapping, 0);
255 if (!page)
256 return -EFAULT; /* page not mapped */
257
258 ret = -EINVAL;
259 page_addr = kmap_atomic(page);
260 ehdr = (Elf32_Ehdr *)page_addr;
261
262 /* compare magic x7f "ELF" */
263 if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0)
264 goto out;
265
266 /* only support executable file and shared object file */
267 if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN)
268 goto out;
269
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);
274out:
275 kunmap_atomic(page_addr);
276 put_page(page);
277 return ret;
278}
279
280static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs,
281 u64 *ips, u32 trace_nr, bool user)
282{
283 int i;
284 struct vm_area_struct *vma;
285 bool irq_work_busy = false;
286 struct stack_map_irq_work *work = NULL;
287
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;
294 }
295 } else {
296 /*
297 * PREEMPT_RT does not allow to trylock mmap sem in
298 * interrupt disabled context. Force the fallback code.
299 */
300 irq_work_busy = true;
301 }
302 }
303
304 /*
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.
310 *
311 * Same fallback is used for kernel stack (!user) on a stackmap
312 * with build_id.
313 */
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);
321 }
322 return;
323 }
324
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);
332 continue;
333 }
334 id_offs[i].offset = (vma->vm_pgoff << PAGE_SHIFT) + ips[i]
335 - vma->vm_start;
336 id_offs[i].status = BPF_STACK_BUILD_ID_VALID;
337 }
338
339 if (!work) {
340 mmap_read_unlock_non_owner(current->mm);
341 } else {
342 work->mm = current->mm;
343 irq_work_queue(&work->irq_work);
344 }
345}
346
347static struct perf_callchain_entry *
348get_callchain_entry_for_task(struct task_struct *task, u32 init_nr)
349{
350#ifdef CONFIG_STACKTRACE
351 struct perf_callchain_entry *entry;
352 int rctx;
353
354 entry = get_callchain_entry(&rctx);
355
356 if (!entry)
357 return NULL;
358
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);
362
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.
366 */
367 if (__BITS_PER_LONG != 64) {
368 unsigned long *from = (unsigned long *) entry->ip;
369 u64 *to = entry->ip;
370 int i;
371
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]);
375 }
376
377 put_callchain_entry(rctx);
378
379 return entry;
380#else /* CONFIG_STACKTRACE */
381 return NULL;
382#endif
383}
384
385static long __bpf_get_stackid(struct bpf_map *map,
386 struct perf_callchain_entry *trace, u64 flags)
387{
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;
396 u64 *ips;
397 bool hash_matches;
398
399 /* get_perf_callchain() guarantees that trace->nr >= init_nr
400 * and trace-nr <= sysctl_perf_event_max_stack, so trace_nr <= max_depth
401 */
402 trace_nr = trace->nr - init_nr;
403
404 if (trace_nr <= skip)
405 /* skipping more than usable stack trace */
406 return -EFAULT;
407
408 trace_nr -= skip;
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]);
414
415 hash_matches = bucket && bucket->hash == hash;
416 /* fast cmp */
417 if (hash_matches && flags & BPF_F_FAST_STACK_CMP)
418 return id;
419
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))
425 return -ENOMEM;
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);
434 return id;
435 }
436 if (bucket && !(flags & BPF_F_REUSE_STACKID)) {
437 pcpu_freelist_push(&smap->freelist, &new_bucket->fnode);
438 return -EEXIST;
439 }
440 } else {
441 if (hash_matches && bucket->nr == trace_nr &&
442 memcmp(bucket->data, ips, trace_len) == 0)
443 return id;
444 if (bucket && !(flags & BPF_F_REUSE_STACKID))
445 return -EEXIST;
446
447 new_bucket = (struct stack_map_bucket *)
448 pcpu_freelist_pop(&smap->freelist);
449 if (unlikely(!new_bucket))
450 return -ENOMEM;
451 memcpy(new_bucket->data, ips, trace_len);
452 }
453
454 new_bucket->hash = hash;
455 new_bucket->nr = trace_nr;
456
457 old_bucket = xchg(&smap->buckets[id], new_bucket);
458 if (old_bucket)
459 pcpu_freelist_push(&smap->freelist, &old_bucket->fnode);
460 return id;
461}
462
463BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map,
464 u64, flags)
465{
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;
471 bool kernel = !user;
472
473 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
474 BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID)))
475 return -EINVAL;
476
477 trace = get_perf_callchain(regs, init_nr, kernel, user,
478 sysctl_perf_event_max_stack, false, false);
479
480 if (unlikely(!trace))
481 /* couldn't fetch the stack trace */
482 return -EFAULT;
483
484 return __bpf_get_stackid(map, trace, flags);
485}
486
487const struct bpf_func_proto bpf_get_stackid_proto = {
488 .func = bpf_get_stackid,
489 .gpl_only = true,
490 .ret_type = RET_INTEGER,
491 .arg1_type = ARG_PTR_TO_CTX,
492 .arg2_type = ARG_CONST_MAP_PTR,
493 .arg3_type = ARG_ANYTHING,
494};
495
496static __u64 count_kernel_ip(struct perf_callchain_entry *trace)
497{
498 __u64 nr_kernel = 0;
499
500 while (nr_kernel < trace->nr) {
501 if (trace->ip[nr_kernel] == PERF_CONTEXT_USER)
502 break;
503 nr_kernel++;
504 }
505 return nr_kernel;
506}
507
508BPF_CALL_3(bpf_get_stackid_pe, struct bpf_perf_event_data_kern *, ctx,
509 struct bpf_map *, map, u64, flags)
510{
511 struct perf_event *event = ctx->event;
512 struct perf_callchain_entry *trace;
513 bool kernel, user;
514 __u64 nr_kernel;
515 int ret;
516
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);
521
522 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
523 BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID)))
524 return -EINVAL;
525
526 user = flags & BPF_F_USER_STACK;
527 kernel = !user;
528
529 trace = ctx->data->callchain;
530 if (unlikely(!trace))
531 return -EFAULT;
532
533 nr_kernel = count_kernel_ip(trace);
534
535 if (kernel) {
536 __u64 nr = trace->nr;
537
538 trace->nr = nr_kernel;
539 ret = __bpf_get_stackid(map, trace, 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 return -EFAULT;
549
550 flags = (flags & ~BPF_F_SKIP_FIELD_MASK) | skip;
551 ret = __bpf_get_stackid(map, trace, flags);
552 }
553 return ret;
554}
555
556const struct bpf_func_proto bpf_get_stackid_proto_pe = {
557 .func = bpf_get_stackid_pe,
558 .gpl_only = false,
559 .ret_type = RET_INTEGER,
560 .arg1_type = ARG_PTR_TO_CTX,
561 .arg2_type = ARG_CONST_MAP_PTR,
562 .arg3_type = ARG_ANYTHING,
563};
564
565static 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)
568{
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;
574 bool kernel = !user;
575 int err = -EINVAL;
576 u64 *ips;
577
578 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
579 BPF_F_USER_BUILD_ID)))
580 goto clear;
581 if (kernel && user_build_id)
582 goto clear;
583
584 elem_size = (user && user_build_id) ? sizeof(struct bpf_stack_build_id)
585 : sizeof(u64);
586 if (unlikely(size % elem_size))
587 goto clear;
588
589 /* cannot get valid user stack for task without user_mode regs */
590 if (task && user && !user_mode(regs))
591 goto err_fault;
592
593 num_elem = size / elem_size;
594 if (sysctl_perf_event_max_stack < num_elem)
595 init_nr = 0;
596 else
597 init_nr = sysctl_perf_event_max_stack - num_elem;
598
599 if (trace_in)
600 trace = trace_in;
601 else if (kernel && task)
602 trace = get_callchain_entry_for_task(task, init_nr);
603 else
604 trace = get_perf_callchain(regs, init_nr, kernel, user,
605 sysctl_perf_event_max_stack,
606 false, false);
607 if (unlikely(!trace))
608 goto err_fault;
609
610 trace_nr = trace->nr - init_nr;
611 if (trace_nr < skip)
612 goto err_fault;
613
614 trace_nr -= skip;
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);
620 else
621 memcpy(buf, ips, copy_len);
622
623 if (size > copy_len)
624 memset(buf + copy_len, 0, size - copy_len);
625 return copy_len;
626
627err_fault:
628 err = -EFAULT;
629clear:
630 memset(buf, 0, size);
631 return err;
632}
633
634BPF_CALL_4(bpf_get_stack, struct pt_regs *, regs, void *, buf, u32, size,
635 u64, flags)
636{
637 return __bpf_get_stack(regs, NULL, NULL, buf, size, flags);
638}
639
640const struct bpf_func_proto bpf_get_stack_proto = {
641 .func = bpf_get_stack,
642 .gpl_only = true,
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,
648};
649
650BPF_CALL_4(bpf_get_task_stack, struct task_struct *, task, void *, buf,
651 u32, size, u64, flags)
652{
653 struct pt_regs *regs = task_pt_regs(task);
654
655 return __bpf_get_stack(regs, task, NULL, buf, size, flags);
656}
657
658BTF_ID_LIST_SINGLE(bpf_get_task_stack_btf_ids, struct, task_struct)
659
660const struct bpf_func_proto bpf_get_task_stack_proto = {
661 .func = bpf_get_task_stack,
662 .gpl_only = false,
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,
669};
670
671BPF_CALL_4(bpf_get_stack_pe, struct bpf_perf_event_data_kern *, ctx,
672 void *, buf, u32, size, u64, flags)
673{
674 struct pt_regs *regs = (struct pt_regs *)(ctx->regs);
675 struct perf_event *event = ctx->event;
676 struct perf_callchain_entry *trace;
677 bool kernel, user;
678 int err = -EINVAL;
679 __u64 nr_kernel;
680
681 if (!(event->attr.sample_type & __PERF_SAMPLE_CALLCHAIN_EARLY))
682 return __bpf_get_stack(regs, NULL, NULL, buf, size, flags);
683
684 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
685 BPF_F_USER_BUILD_ID)))
686 goto clear;
687
688 user = flags & BPF_F_USER_STACK;
689 kernel = !user;
690
691 err = -EFAULT;
692 trace = ctx->data->callchain;
693 if (unlikely(!trace))
694 goto clear;
695
696 nr_kernel = count_kernel_ip(trace);
697
698 if (kernel) {
699 __u64 nr = trace->nr;
700
701 trace->nr = nr_kernel;
702 err = __bpf_get_stack(regs, NULL, trace, buf, size, flags);
703
704 /* restore nr */
705 trace->nr = nr;
706 } else { /* user */
707 u64 skip = flags & BPF_F_SKIP_FIELD_MASK;
708
709 skip += nr_kernel;
710 if (skip > BPF_F_SKIP_FIELD_MASK)
711 goto clear;
712
713 flags = (flags & ~BPF_F_SKIP_FIELD_MASK) | skip;
714 err = __bpf_get_stack(regs, NULL, trace, buf, size, flags);
715 }
716 return err;
717
718clear:
719 memset(buf, 0, size);
720 return err;
721
722}
723
724const struct bpf_func_proto bpf_get_stack_proto_pe = {
725 .func = bpf_get_stack_pe,
726 .gpl_only = true,
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,
732};
733
734/* Called from eBPF program */
735static void *stack_map_lookup_elem(struct bpf_map *map, void *key)
736{
737 return ERR_PTR(-EOPNOTSUPP);
738}
739
740/* Called from syscall */
741int bpf_stackmap_copy(struct bpf_map *map, void *key, void *value)
742{
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;
746
747 if (unlikely(id >= smap->n_buckets))
748 return -ENOENT;
749
750 bucket = xchg(&smap->buckets[id], NULL);
751 if (!bucket)
752 return -ENOENT;
753
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);
757
758 old_bucket = xchg(&smap->buckets[id], bucket);
759 if (old_bucket)
760 pcpu_freelist_push(&smap->freelist, &old_bucket->fnode);
761 return 0;
762}
763
764static int stack_map_get_next_key(struct bpf_map *map, void *key,
765 void *next_key)
766{
767 struct bpf_stack_map *smap = container_of(map,
768 struct bpf_stack_map, map);
769 u32 id;
770
771 WARN_ON_ONCE(!rcu_read_lock_held());
772
773 if (!key) {
774 id = 0;
775 } else {
776 id = *(u32 *)key;
777 if (id >= smap->n_buckets || !smap->buckets[id])
778 id = 0;
779 else
780 id++;
781 }
782
783 while (id < smap->n_buckets && !smap->buckets[id])
784 id++;
785
786 if (id >= smap->n_buckets)
787 return -ENOENT;
788
789 *(u32 *)next_key = id;
790 return 0;
791}
792
793static int stack_map_update_elem(struct bpf_map *map, void *key, void *value,
794 u64 map_flags)
795{
796 return -EINVAL;
797}
798
799/* Called from syscall or from eBPF program */
800static int stack_map_delete_elem(struct bpf_map *map, void *key)
801{
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;
805
806 if (unlikely(id >= smap->n_buckets))
807 return -E2BIG;
808
809 old_bucket = xchg(&smap->buckets[id], NULL);
810 if (old_bucket) {
811 pcpu_freelist_push(&smap->freelist, &old_bucket->fnode);
812 return 0;
813 } else {
814 return -ENOENT;
815 }
816}
817
818/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
819static void stack_map_free(struct bpf_map *map)
820{
821 struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);
822
823 bpf_map_area_free(smap->elems);
824 pcpu_freelist_destroy(&smap->freelist);
825 bpf_map_area_free(smap);
826 put_callchain_buffers();
827}
828
829static int stack_trace_map_btf_id;
830const 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,
841};
842
843static int __init stack_map_init(void)
844{
845 int cpu;
846 struct stack_map_irq_work *work;
847
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);
851 }
852 return 0;
853}
854subsys_initcall(stack_map_init);