Commit | Line | Data |
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d5a3b1f6 AS |
1 | /* Copyright (c) 2016 Facebook |
2 | * | |
3 | * This program is free software; you can redistribute it and/or | |
4 | * modify it under the terms of version 2 of the GNU General Public | |
5 | * License as published by the Free Software Foundation. | |
6 | */ | |
7 | #include <linux/bpf.h> | |
8 | #include <linux/jhash.h> | |
9 | #include <linux/filter.h> | |
d5a3b1f6 AS |
10 | #include <linux/stacktrace.h> |
11 | #include <linux/perf_event.h> | |
615755a7 SL |
12 | #include <linux/elf.h> |
13 | #include <linux/pagemap.h> | |
557c0c6e | 14 | #include "percpu_freelist.h" |
d5a3b1f6 | 15 | |
615755a7 SL |
16 | #define STACK_CREATE_FLAG_MASK \ |
17 | (BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY | \ | |
18 | BPF_F_STACK_BUILD_ID) | |
6e71b04a | 19 | |
d5a3b1f6 | 20 | struct stack_map_bucket { |
557c0c6e | 21 | struct pcpu_freelist_node fnode; |
d5a3b1f6 AS |
22 | u32 hash; |
23 | u32 nr; | |
615755a7 | 24 | u64 data[]; |
d5a3b1f6 AS |
25 | }; |
26 | ||
27 | struct bpf_stack_map { | |
28 | struct bpf_map map; | |
557c0c6e AS |
29 | void *elems; |
30 | struct pcpu_freelist freelist; | |
d5a3b1f6 | 31 | u32 n_buckets; |
557c0c6e | 32 | struct stack_map_bucket *buckets[]; |
d5a3b1f6 AS |
33 | }; |
34 | ||
615755a7 SL |
35 | static inline bool stack_map_use_build_id(struct bpf_map *map) |
36 | { | |
37 | return (map->map_flags & BPF_F_STACK_BUILD_ID); | |
38 | } | |
39 | ||
40 | static inline int stack_map_data_size(struct bpf_map *map) | |
41 | { | |
42 | return stack_map_use_build_id(map) ? | |
43 | sizeof(struct bpf_stack_build_id) : sizeof(u64); | |
44 | } | |
45 | ||
557c0c6e AS |
46 | static int prealloc_elems_and_freelist(struct bpf_stack_map *smap) |
47 | { | |
48 | u32 elem_size = sizeof(struct stack_map_bucket) + smap->map.value_size; | |
49 | int err; | |
50 | ||
96eabe7a MKL |
51 | smap->elems = bpf_map_area_alloc(elem_size * smap->map.max_entries, |
52 | smap->map.numa_node); | |
557c0c6e AS |
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(&smap->freelist, smap->elems, elem_size, | |
61 | smap->map.max_entries); | |
62 | return 0; | |
63 | ||
64 | free_elems: | |
d407bd25 | 65 | bpf_map_area_free(smap->elems); |
557c0c6e AS |
66 | return err; |
67 | } | |
68 | ||
d5a3b1f6 AS |
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 (!capable(CAP_SYS_ADMIN)) | |
78 | return ERR_PTR(-EPERM); | |
79 | ||
6e71b04a | 80 | if (attr->map_flags & ~STACK_CREATE_FLAG_MASK) |
823707b6 AS |
81 | return ERR_PTR(-EINVAL); |
82 | ||
d5a3b1f6 AS |
83 | /* check sanity of attributes */ |
84 | if (attr->max_entries == 0 || attr->key_size != 4 || | |
615755a7 SL |
85 | value_size < 8 || value_size % 8) |
86 | return ERR_PTR(-EINVAL); | |
87 | ||
88 | BUILD_BUG_ON(sizeof(struct bpf_stack_build_id) % sizeof(u64)); | |
89 | if (attr->map_flags & BPF_F_STACK_BUILD_ID) { | |
90 | if (value_size % sizeof(struct bpf_stack_build_id) || | |
91 | value_size / sizeof(struct bpf_stack_build_id) | |
92 | > sysctl_perf_event_max_stack) | |
93 | return ERR_PTR(-EINVAL); | |
94 | } else if (value_size / 8 > sysctl_perf_event_max_stack) | |
d5a3b1f6 AS |
95 | return ERR_PTR(-EINVAL); |
96 | ||
97 | /* hash table size must be power of 2 */ | |
98 | n_buckets = roundup_pow_of_two(attr->max_entries); | |
99 | ||
100 | cost = n_buckets * sizeof(struct stack_map_bucket *) + sizeof(*smap); | |
101 | if (cost >= U32_MAX - PAGE_SIZE) | |
102 | return ERR_PTR(-E2BIG); | |
103 | ||
96eabe7a | 104 | smap = bpf_map_area_alloc(cost, bpf_map_attr_numa_node(attr)); |
d407bd25 DB |
105 | if (!smap) |
106 | return ERR_PTR(-ENOMEM); | |
d5a3b1f6 AS |
107 | |
108 | err = -E2BIG; | |
109 | cost += n_buckets * (value_size + sizeof(struct stack_map_bucket)); | |
110 | if (cost >= U32_MAX - PAGE_SIZE) | |
111 | goto free_smap; | |
112 | ||
bd475643 | 113 | bpf_map_init_from_attr(&smap->map, attr); |
d5a3b1f6 | 114 | smap->map.value_size = value_size; |
d5a3b1f6 AS |
115 | smap->n_buckets = n_buckets; |
116 | smap->map.pages = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT; | |
117 | ||
557c0c6e AS |
118 | err = bpf_map_precharge_memlock(smap->map.pages); |
119 | if (err) | |
120 | goto free_smap; | |
121 | ||
97c79a38 | 122 | err = get_callchain_buffers(sysctl_perf_event_max_stack); |
d5a3b1f6 AS |
123 | if (err) |
124 | goto free_smap; | |
125 | ||
557c0c6e AS |
126 | err = prealloc_elems_and_freelist(smap); |
127 | if (err) | |
128 | goto put_buffers; | |
129 | ||
d5a3b1f6 AS |
130 | return &smap->map; |
131 | ||
557c0c6e AS |
132 | put_buffers: |
133 | put_callchain_buffers(); | |
d5a3b1f6 | 134 | free_smap: |
d407bd25 | 135 | bpf_map_area_free(smap); |
d5a3b1f6 AS |
136 | return ERR_PTR(err); |
137 | } | |
138 | ||
615755a7 SL |
139 | #define BPF_BUILD_ID 3 |
140 | /* | |
141 | * Parse build id from the note segment. This logic can be shared between | |
142 | * 32-bit and 64-bit system, because Elf32_Nhdr and Elf64_Nhdr are | |
143 | * identical. | |
144 | */ | |
145 | static inline int stack_map_parse_build_id(void *page_addr, | |
146 | unsigned char *build_id, | |
147 | void *note_start, | |
148 | Elf32_Word note_size) | |
149 | { | |
150 | Elf32_Word note_offs = 0, new_offs; | |
151 | ||
152 | /* check for overflow */ | |
153 | if (note_start < page_addr || note_start + note_size < note_start) | |
154 | return -EINVAL; | |
155 | ||
156 | /* only supports note that fits in the first page */ | |
157 | if (note_start + note_size > page_addr + PAGE_SIZE) | |
158 | return -EINVAL; | |
159 | ||
160 | while (note_offs + sizeof(Elf32_Nhdr) < note_size) { | |
161 | Elf32_Nhdr *nhdr = (Elf32_Nhdr *)(note_start + note_offs); | |
162 | ||
163 | if (nhdr->n_type == BPF_BUILD_ID && | |
164 | nhdr->n_namesz == sizeof("GNU") && | |
165 | nhdr->n_descsz == BPF_BUILD_ID_SIZE) { | |
166 | memcpy(build_id, | |
167 | note_start + note_offs + | |
168 | ALIGN(sizeof("GNU"), 4) + sizeof(Elf32_Nhdr), | |
169 | BPF_BUILD_ID_SIZE); | |
170 | return 0; | |
171 | } | |
172 | new_offs = note_offs + sizeof(Elf32_Nhdr) + | |
173 | ALIGN(nhdr->n_namesz, 4) + ALIGN(nhdr->n_descsz, 4); | |
174 | if (new_offs <= note_offs) /* overflow */ | |
175 | break; | |
176 | note_offs = new_offs; | |
177 | } | |
178 | return -EINVAL; | |
179 | } | |
180 | ||
181 | /* Parse build ID from 32-bit ELF */ | |
182 | static int stack_map_get_build_id_32(void *page_addr, | |
183 | unsigned char *build_id) | |
184 | { | |
185 | Elf32_Ehdr *ehdr = (Elf32_Ehdr *)page_addr; | |
186 | Elf32_Phdr *phdr; | |
187 | int i; | |
188 | ||
189 | /* only supports phdr that fits in one page */ | |
190 | if (ehdr->e_phnum > | |
191 | (PAGE_SIZE - sizeof(Elf32_Ehdr)) / sizeof(Elf32_Phdr)) | |
192 | return -EINVAL; | |
193 | ||
194 | phdr = (Elf32_Phdr *)(page_addr + sizeof(Elf32_Ehdr)); | |
195 | ||
196 | for (i = 0; i < ehdr->e_phnum; ++i) | |
197 | if (phdr[i].p_type == PT_NOTE) | |
198 | return stack_map_parse_build_id(page_addr, build_id, | |
199 | page_addr + phdr[i].p_offset, | |
200 | phdr[i].p_filesz); | |
201 | return -EINVAL; | |
202 | } | |
203 | ||
204 | /* Parse build ID from 64-bit ELF */ | |
205 | static int stack_map_get_build_id_64(void *page_addr, | |
206 | unsigned char *build_id) | |
207 | { | |
208 | Elf64_Ehdr *ehdr = (Elf64_Ehdr *)page_addr; | |
209 | Elf64_Phdr *phdr; | |
210 | int i; | |
211 | ||
212 | /* only supports phdr that fits in one page */ | |
213 | if (ehdr->e_phnum > | |
214 | (PAGE_SIZE - sizeof(Elf64_Ehdr)) / sizeof(Elf64_Phdr)) | |
215 | return -EINVAL; | |
216 | ||
217 | phdr = (Elf64_Phdr *)(page_addr + sizeof(Elf64_Ehdr)); | |
218 | ||
219 | for (i = 0; i < ehdr->e_phnum; ++i) | |
220 | if (phdr[i].p_type == PT_NOTE) | |
221 | return stack_map_parse_build_id(page_addr, build_id, | |
222 | page_addr + phdr[i].p_offset, | |
223 | phdr[i].p_filesz); | |
224 | return -EINVAL; | |
225 | } | |
226 | ||
227 | /* Parse build ID of ELF file mapped to vma */ | |
228 | static int stack_map_get_build_id(struct vm_area_struct *vma, | |
229 | unsigned char *build_id) | |
230 | { | |
231 | Elf32_Ehdr *ehdr; | |
232 | struct page *page; | |
233 | void *page_addr; | |
234 | int ret; | |
235 | ||
236 | /* only works for page backed storage */ | |
237 | if (!vma->vm_file) | |
238 | return -EINVAL; | |
239 | ||
240 | page = find_get_page(vma->vm_file->f_mapping, 0); | |
241 | if (!page) | |
242 | return -EFAULT; /* page not mapped */ | |
243 | ||
244 | ret = -EINVAL; | |
245 | page_addr = page_address(page); | |
246 | ehdr = (Elf32_Ehdr *)page_addr; | |
247 | ||
248 | /* compare magic x7f "ELF" */ | |
249 | if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0) | |
250 | goto out; | |
251 | ||
252 | /* only support executable file and shared object file */ | |
253 | if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN) | |
254 | goto out; | |
255 | ||
256 | if (ehdr->e_ident[EI_CLASS] == ELFCLASS32) | |
257 | ret = stack_map_get_build_id_32(page_addr, build_id); | |
258 | else if (ehdr->e_ident[EI_CLASS] == ELFCLASS64) | |
259 | ret = stack_map_get_build_id_64(page_addr, build_id); | |
260 | out: | |
261 | put_page(page); | |
262 | return ret; | |
263 | } | |
264 | ||
5f412632 | 265 | static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs, |
615755a7 SL |
266 | u64 *ips, u32 trace_nr, bool user) |
267 | { | |
268 | int i; | |
269 | struct vm_area_struct *vma; | |
615755a7 SL |
270 | |
271 | /* | |
272 | * We cannot do up_read() in nmi context, so build_id lookup is | |
273 | * only supported for non-nmi events. If at some point, it is | |
274 | * possible to run find_vma() without taking the semaphore, we | |
275 | * would like to allow build_id lookup in nmi context. | |
276 | * | |
277 | * Same fallback is used for kernel stack (!user) on a stackmap | |
278 | * with build_id. | |
279 | */ | |
280 | if (!user || !current || !current->mm || in_nmi() || | |
281 | down_read_trylock(¤t->mm->mmap_sem) == 0) { | |
282 | /* cannot access current->mm, fall back to ips */ | |
283 | for (i = 0; i < trace_nr; i++) { | |
284 | id_offs[i].status = BPF_STACK_BUILD_ID_IP; | |
285 | id_offs[i].ip = ips[i]; | |
286 | } | |
287 | return; | |
288 | } | |
289 | ||
290 | for (i = 0; i < trace_nr; i++) { | |
291 | vma = find_vma(current->mm, ips[i]); | |
292 | if (!vma || stack_map_get_build_id(vma, id_offs[i].build_id)) { | |
293 | /* per entry fall back to ips */ | |
294 | id_offs[i].status = BPF_STACK_BUILD_ID_IP; | |
295 | id_offs[i].ip = ips[i]; | |
296 | continue; | |
297 | } | |
298 | id_offs[i].offset = (vma->vm_pgoff << PAGE_SHIFT) + ips[i] | |
299 | - vma->vm_start; | |
300 | id_offs[i].status = BPF_STACK_BUILD_ID_VALID; | |
301 | } | |
302 | up_read(¤t->mm->mmap_sem); | |
303 | } | |
304 | ||
f3694e00 DB |
305 | BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map, |
306 | u64, flags) | |
d5a3b1f6 | 307 | { |
d5a3b1f6 AS |
308 | struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); |
309 | struct perf_callchain_entry *trace; | |
310 | struct stack_map_bucket *bucket, *new_bucket, *old_bucket; | |
615755a7 | 311 | u32 max_depth = map->value_size / stack_map_data_size(map); |
c5dfd78e ACM |
312 | /* stack_map_alloc() checks that max_depth <= sysctl_perf_event_max_stack */ |
313 | u32 init_nr = sysctl_perf_event_max_stack - max_depth; | |
d5a3b1f6 AS |
314 | u32 skip = flags & BPF_F_SKIP_FIELD_MASK; |
315 | u32 hash, id, trace_nr, trace_len; | |
316 | bool user = flags & BPF_F_USER_STACK; | |
317 | bool kernel = !user; | |
318 | u64 *ips; | |
615755a7 | 319 | bool hash_matches; |
d5a3b1f6 AS |
320 | |
321 | if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | | |
322 | BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID))) | |
323 | return -EINVAL; | |
324 | ||
cfbcf468 ACM |
325 | trace = get_perf_callchain(regs, init_nr, kernel, user, |
326 | sysctl_perf_event_max_stack, false, false); | |
d5a3b1f6 AS |
327 | |
328 | if (unlikely(!trace)) | |
329 | /* couldn't fetch the stack trace */ | |
330 | return -EFAULT; | |
331 | ||
332 | /* get_perf_callchain() guarantees that trace->nr >= init_nr | |
c5dfd78e | 333 | * and trace-nr <= sysctl_perf_event_max_stack, so trace_nr <= max_depth |
d5a3b1f6 AS |
334 | */ |
335 | trace_nr = trace->nr - init_nr; | |
336 | ||
337 | if (trace_nr <= skip) | |
338 | /* skipping more than usable stack trace */ | |
339 | return -EFAULT; | |
340 | ||
341 | trace_nr -= skip; | |
342 | trace_len = trace_nr * sizeof(u64); | |
343 | ips = trace->ip + skip + init_nr; | |
344 | hash = jhash2((u32 *)ips, trace_len / sizeof(u32), 0); | |
345 | id = hash & (smap->n_buckets - 1); | |
557c0c6e | 346 | bucket = READ_ONCE(smap->buckets[id]); |
d5a3b1f6 | 347 | |
615755a7 SL |
348 | hash_matches = bucket && bucket->hash == hash; |
349 | /* fast cmp */ | |
350 | if (hash_matches && flags & BPF_F_FAST_STACK_CMP) | |
351 | return id; | |
352 | ||
353 | if (stack_map_use_build_id(map)) { | |
354 | /* for build_id+offset, pop a bucket before slow cmp */ | |
355 | new_bucket = (struct stack_map_bucket *) | |
356 | pcpu_freelist_pop(&smap->freelist); | |
357 | if (unlikely(!new_bucket)) | |
358 | return -ENOMEM; | |
5f412632 YS |
359 | new_bucket->nr = trace_nr; |
360 | stack_map_get_build_id_offset( | |
361 | (struct bpf_stack_build_id *)new_bucket->data, | |
362 | ips, trace_nr, user); | |
615755a7 SL |
363 | trace_len = trace_nr * sizeof(struct bpf_stack_build_id); |
364 | if (hash_matches && bucket->nr == trace_nr && | |
365 | memcmp(bucket->data, new_bucket->data, trace_len) == 0) { | |
366 | pcpu_freelist_push(&smap->freelist, &new_bucket->fnode); | |
d5a3b1f6 | 367 | return id; |
615755a7 SL |
368 | } |
369 | if (bucket && !(flags & BPF_F_REUSE_STACKID)) { | |
370 | pcpu_freelist_push(&smap->freelist, &new_bucket->fnode); | |
371 | return -EEXIST; | |
372 | } | |
373 | } else { | |
374 | if (hash_matches && bucket->nr == trace_nr && | |
375 | memcmp(bucket->data, ips, trace_len) == 0) | |
d5a3b1f6 | 376 | return id; |
615755a7 SL |
377 | if (bucket && !(flags & BPF_F_REUSE_STACKID)) |
378 | return -EEXIST; | |
379 | ||
380 | new_bucket = (struct stack_map_bucket *) | |
381 | pcpu_freelist_pop(&smap->freelist); | |
382 | if (unlikely(!new_bucket)) | |
383 | return -ENOMEM; | |
384 | memcpy(new_bucket->data, ips, trace_len); | |
d5a3b1f6 AS |
385 | } |
386 | ||
d5a3b1f6 AS |
387 | new_bucket->hash = hash; |
388 | new_bucket->nr = trace_nr; | |
389 | ||
390 | old_bucket = xchg(&smap->buckets[id], new_bucket); | |
391 | if (old_bucket) | |
557c0c6e | 392 | pcpu_freelist_push(&smap->freelist, &old_bucket->fnode); |
d5a3b1f6 AS |
393 | return id; |
394 | } | |
395 | ||
396 | const struct bpf_func_proto bpf_get_stackid_proto = { | |
397 | .func = bpf_get_stackid, | |
398 | .gpl_only = true, | |
399 | .ret_type = RET_INTEGER, | |
400 | .arg1_type = ARG_PTR_TO_CTX, | |
401 | .arg2_type = ARG_CONST_MAP_PTR, | |
402 | .arg3_type = ARG_ANYTHING, | |
403 | }; | |
404 | ||
c195651e YS |
405 | BPF_CALL_4(bpf_get_stack, struct pt_regs *, regs, void *, buf, u32, size, |
406 | u64, flags) | |
407 | { | |
408 | u32 init_nr, trace_nr, copy_len, elem_size, num_elem; | |
409 | bool user_build_id = flags & BPF_F_USER_BUILD_ID; | |
410 | u32 skip = flags & BPF_F_SKIP_FIELD_MASK; | |
411 | bool user = flags & BPF_F_USER_STACK; | |
412 | struct perf_callchain_entry *trace; | |
413 | bool kernel = !user; | |
414 | int err = -EINVAL; | |
415 | u64 *ips; | |
416 | ||
417 | if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | | |
418 | BPF_F_USER_BUILD_ID))) | |
419 | goto clear; | |
420 | if (kernel && user_build_id) | |
421 | goto clear; | |
422 | ||
423 | elem_size = (user && user_build_id) ? sizeof(struct bpf_stack_build_id) | |
424 | : sizeof(u64); | |
425 | if (unlikely(size % elem_size)) | |
426 | goto clear; | |
427 | ||
428 | num_elem = size / elem_size; | |
429 | if (sysctl_perf_event_max_stack < num_elem) | |
430 | init_nr = 0; | |
431 | else | |
432 | init_nr = sysctl_perf_event_max_stack - num_elem; | |
433 | trace = get_perf_callchain(regs, init_nr, kernel, user, | |
434 | sysctl_perf_event_max_stack, false, false); | |
435 | if (unlikely(!trace)) | |
436 | goto err_fault; | |
437 | ||
438 | trace_nr = trace->nr - init_nr; | |
439 | if (trace_nr < skip) | |
440 | goto err_fault; | |
441 | ||
442 | trace_nr -= skip; | |
443 | trace_nr = (trace_nr <= num_elem) ? trace_nr : num_elem; | |
444 | copy_len = trace_nr * elem_size; | |
445 | ips = trace->ip + skip + init_nr; | |
446 | if (user && user_build_id) | |
447 | stack_map_get_build_id_offset(buf, ips, trace_nr, user); | |
448 | else | |
449 | memcpy(buf, ips, copy_len); | |
450 | ||
451 | if (size > copy_len) | |
452 | memset(buf + copy_len, 0, size - copy_len); | |
453 | return copy_len; | |
454 | ||
455 | err_fault: | |
456 | err = -EFAULT; | |
457 | clear: | |
458 | memset(buf, 0, size); | |
459 | return err; | |
460 | } | |
461 | ||
462 | const struct bpf_func_proto bpf_get_stack_proto = { | |
463 | .func = bpf_get_stack, | |
464 | .gpl_only = true, | |
465 | .ret_type = RET_INTEGER, | |
466 | .arg1_type = ARG_PTR_TO_CTX, | |
467 | .arg2_type = ARG_PTR_TO_UNINIT_MEM, | |
468 | .arg3_type = ARG_CONST_SIZE_OR_ZERO, | |
469 | .arg4_type = ARG_ANYTHING, | |
470 | }; | |
471 | ||
557c0c6e | 472 | /* Called from eBPF program */ |
d5a3b1f6 | 473 | static void *stack_map_lookup_elem(struct bpf_map *map, void *key) |
557c0c6e AS |
474 | { |
475 | return NULL; | |
476 | } | |
477 | ||
478 | /* Called from syscall */ | |
479 | int bpf_stackmap_copy(struct bpf_map *map, void *key, void *value) | |
d5a3b1f6 AS |
480 | { |
481 | struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); | |
557c0c6e AS |
482 | struct stack_map_bucket *bucket, *old_bucket; |
483 | u32 id = *(u32 *)key, trace_len; | |
d5a3b1f6 AS |
484 | |
485 | if (unlikely(id >= smap->n_buckets)) | |
557c0c6e AS |
486 | return -ENOENT; |
487 | ||
488 | bucket = xchg(&smap->buckets[id], NULL); | |
489 | if (!bucket) | |
490 | return -ENOENT; | |
491 | ||
615755a7 SL |
492 | trace_len = bucket->nr * stack_map_data_size(map); |
493 | memcpy(value, bucket->data, trace_len); | |
557c0c6e AS |
494 | memset(value + trace_len, 0, map->value_size - trace_len); |
495 | ||
496 | old_bucket = xchg(&smap->buckets[id], bucket); | |
497 | if (old_bucket) | |
498 | pcpu_freelist_push(&smap->freelist, &old_bucket->fnode); | |
499 | return 0; | |
d5a3b1f6 AS |
500 | } |
501 | ||
16f07c55 YS |
502 | static int stack_map_get_next_key(struct bpf_map *map, void *key, |
503 | void *next_key) | |
d5a3b1f6 | 504 | { |
16f07c55 YS |
505 | struct bpf_stack_map *smap = container_of(map, |
506 | struct bpf_stack_map, map); | |
507 | u32 id; | |
508 | ||
509 | WARN_ON_ONCE(!rcu_read_lock_held()); | |
510 | ||
511 | if (!key) { | |
512 | id = 0; | |
513 | } else { | |
514 | id = *(u32 *)key; | |
515 | if (id >= smap->n_buckets || !smap->buckets[id]) | |
516 | id = 0; | |
517 | else | |
518 | id++; | |
519 | } | |
520 | ||
521 | while (id < smap->n_buckets && !smap->buckets[id]) | |
522 | id++; | |
523 | ||
524 | if (id >= smap->n_buckets) | |
525 | return -ENOENT; | |
526 | ||
527 | *(u32 *)next_key = id; | |
528 | return 0; | |
d5a3b1f6 AS |
529 | } |
530 | ||
531 | static int stack_map_update_elem(struct bpf_map *map, void *key, void *value, | |
532 | u64 map_flags) | |
533 | { | |
534 | return -EINVAL; | |
535 | } | |
536 | ||
537 | /* Called from syscall or from eBPF program */ | |
538 | static int stack_map_delete_elem(struct bpf_map *map, void *key) | |
539 | { | |
540 | struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); | |
541 | struct stack_map_bucket *old_bucket; | |
542 | u32 id = *(u32 *)key; | |
543 | ||
544 | if (unlikely(id >= smap->n_buckets)) | |
545 | return -E2BIG; | |
546 | ||
547 | old_bucket = xchg(&smap->buckets[id], NULL); | |
548 | if (old_bucket) { | |
557c0c6e | 549 | pcpu_freelist_push(&smap->freelist, &old_bucket->fnode); |
d5a3b1f6 AS |
550 | return 0; |
551 | } else { | |
552 | return -ENOENT; | |
553 | } | |
554 | } | |
555 | ||
556 | /* Called when map->refcnt goes to zero, either from workqueue or from syscall */ | |
557 | static void stack_map_free(struct bpf_map *map) | |
558 | { | |
559 | struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); | |
d5a3b1f6 | 560 | |
557c0c6e | 561 | /* wait for bpf programs to complete before freeing stack map */ |
d5a3b1f6 AS |
562 | synchronize_rcu(); |
563 | ||
d407bd25 | 564 | bpf_map_area_free(smap->elems); |
557c0c6e | 565 | pcpu_freelist_destroy(&smap->freelist); |
d407bd25 | 566 | bpf_map_area_free(smap); |
d5a3b1f6 AS |
567 | put_callchain_buffers(); |
568 | } | |
569 | ||
40077e0c | 570 | const struct bpf_map_ops stack_map_ops = { |
d5a3b1f6 AS |
571 | .map_alloc = stack_map_alloc, |
572 | .map_free = stack_map_free, | |
573 | .map_get_next_key = stack_map_get_next_key, | |
574 | .map_lookup_elem = stack_map_lookup_elem, | |
575 | .map_update_elem = stack_map_update_elem, | |
576 | .map_delete_elem = stack_map_delete_elem, | |
577 | }; |