Commit | Line | Data |
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1802d0be | 1 | // SPDX-License-Identifier: GPL-2.0-only |
cd11016e | 2 | /* |
b232b999 | 3 | * Stack depot - a stack trace storage that avoids duplication. |
cd11016e | 4 | * |
b232b999 AK |
5 | * Internally, stack depot maintains a hash table of unique stacktraces. The |
6 | * stack traces themselves are stored contiguously one after another in a set | |
7 | * of separate page allocations. | |
8 | * | |
cd11016e AP |
9 | * Author: Alexander Potapenko <glider@google.com> |
10 | * Copyright (C) 2016 Google, Inc. | |
11 | * | |
b232b999 | 12 | * Based on the code by Dmitry Chernenkov. |
cd11016e AP |
13 | */ |
14 | ||
4a6b5314 AK |
15 | #define pr_fmt(fmt) "stackdepot: " fmt |
16 | ||
cd11016e AP |
17 | #include <linux/gfp.h> |
18 | #include <linux/jhash.h> | |
19 | #include <linux/kernel.h> | |
8e00b2df | 20 | #include <linux/kmsan.h> |
cd11016e | 21 | #include <linux/mm.h> |
2dba5eb1 | 22 | #include <linux/mutex.h> |
cd11016e AP |
23 | #include <linux/percpu.h> |
24 | #include <linux/printk.h> | |
25 | #include <linux/slab.h> | |
26 | #include <linux/stacktrace.h> | |
27 | #include <linux/stackdepot.h> | |
28 | #include <linux/string.h> | |
29 | #include <linux/types.h> | |
e1fdc403 | 30 | #include <linux/memblock.h> |
f9987921 | 31 | #include <linux/kasan-enabled.h> |
cd11016e | 32 | |
424cafee AK |
33 | #define DEPOT_HANDLE_BITS (sizeof(depot_stack_handle_t) * 8) |
34 | ||
35 | #define DEPOT_VALID_BITS 1 | |
36 | #define DEPOT_POOL_ORDER 2 /* Pool size order, 4 pages */ | |
37 | #define DEPOT_POOL_SIZE (1LL << (PAGE_SHIFT + DEPOT_POOL_ORDER)) | |
38 | #define DEPOT_STACK_ALIGN 4 | |
39 | #define DEPOT_OFFSET_BITS (DEPOT_POOL_ORDER + PAGE_SHIFT - DEPOT_STACK_ALIGN) | |
40 | #define DEPOT_POOL_INDEX_BITS (DEPOT_HANDLE_BITS - DEPOT_VALID_BITS - \ | |
41 | DEPOT_OFFSET_BITS - STACK_DEPOT_EXTRA_BITS) | |
42 | #define DEPOT_POOLS_CAP 8192 | |
43 | #define DEPOT_MAX_POOLS \ | |
44 | (((1LL << (DEPOT_POOL_INDEX_BITS)) < DEPOT_POOLS_CAP) ? \ | |
45 | (1LL << (DEPOT_POOL_INDEX_BITS)) : DEPOT_POOLS_CAP) | |
cd11016e | 46 | |
b232b999 | 47 | /* Compact structure that stores a reference to a stack. */ |
cd11016e AP |
48 | union handle_parts { |
49 | depot_stack_handle_t handle; | |
50 | struct { | |
424cafee AK |
51 | u32 pool_index : DEPOT_POOL_INDEX_BITS; |
52 | u32 offset : DEPOT_OFFSET_BITS; | |
53 | u32 valid : DEPOT_VALID_BITS; | |
54 | u32 extra : STACK_DEPOT_EXTRA_BITS; | |
cd11016e AP |
55 | }; |
56 | }; | |
57 | ||
58 | struct stack_record { | |
b232b999 AK |
59 | struct stack_record *next; /* Link in the hash table */ |
60 | u32 hash; /* Hash in the hash table */ | |
61 | u32 size; /* Number of stored frames */ | |
cd11016e | 62 | union handle_parts handle; |
b232b999 | 63 | unsigned long entries[]; /* Variable-sized array of frames */ |
cd11016e AP |
64 | }; |
65 | ||
735df3c3 | 66 | static bool stack_depot_disabled; |
1c0310ad | 67 | static bool __stack_depot_early_init_requested __initdata = IS_ENABLED(CONFIG_STACKDEPOT_ALWAYS_INIT); |
a5f1783b VB |
68 | static bool __stack_depot_early_init_passed __initdata; |
69 | ||
0d249ac0 | 70 | /* Use one hash table bucket per 16 KB of memory. */ |
4c2e9a67 | 71 | #define STACK_HASH_TABLE_SCALE 14 |
0d249ac0 | 72 | /* Limit the number of buckets between 4K and 1M. */ |
4c2e9a67 AK |
73 | #define STACK_BUCKET_NUMBER_ORDER_MIN 12 |
74 | #define STACK_BUCKET_NUMBER_ORDER_MAX 20 | |
0d249ac0 | 75 | /* Initial seed for jhash2. */ |
cd11016e AP |
76 | #define STACK_HASH_SEED 0x9747b28c |
77 | ||
0d249ac0 AK |
78 | /* Hash table of pointers to stored stack traces. */ |
79 | static struct stack_record **stack_table; | |
80 | /* Fixed order of the number of table buckets. Used when KASAN is enabled. */ | |
4c2e9a67 | 81 | static unsigned int stack_bucket_number_order; |
0d249ac0 | 82 | /* Hash mask for indexing the table. */ |
f9987921 VB |
83 | static unsigned int stack_hash_mask; |
84 | ||
0d249ac0 | 85 | /* Array of memory regions that store stack traces. */ |
424cafee | 86 | static void *stack_pools[DEPOT_MAX_POOLS]; |
961c949b AK |
87 | /* Currently used pool in stack_pools. */ |
88 | static int pool_index; | |
89 | /* Offset to the unused space in the currently used pool. */ | |
90 | static size_t pool_offset; | |
0d249ac0 | 91 | /* Lock that protects the variables above. */ |
961c949b | 92 | static DEFINE_RAW_SPINLOCK(pool_lock); |
d11a5621 AK |
93 | /* |
94 | * Stack depot tries to keep an extra pool allocated even before it runs out | |
95 | * of space in the currently used pool. | |
96 | * This flag marks that this next extra pool needs to be allocated and | |
97 | * initialized. It has the value 0 when either the next pool is not yet | |
98 | * initialized or the limit on the number of pools is reached. | |
99 | */ | |
100 | static int next_pool_required = 1; | |
e1fdc403 | 101 | |
735df3c3 | 102 | static int __init disable_stack_depot(char *str) |
e1fdc403 | 103 | { |
64427985 VJ |
104 | int ret; |
105 | ||
735df3c3 AK |
106 | ret = kstrtobool(str, &stack_depot_disabled); |
107 | if (!ret && stack_depot_disabled) { | |
4a6b5314 | 108 | pr_info("disabled\n"); |
e1fdc403 VJ |
109 | stack_table = NULL; |
110 | } | |
111 | return 0; | |
112 | } | |
735df3c3 | 113 | early_param("stack_depot_disable", disable_stack_depot); |
e1fdc403 | 114 | |
1c0310ad | 115 | void __init stack_depot_request_early_init(void) |
a5f1783b | 116 | { |
1c0310ad | 117 | /* Too late to request early init now. */ |
a5f1783b VB |
118 | WARN_ON(__stack_depot_early_init_passed); |
119 | ||
1c0310ad | 120 | __stack_depot_early_init_requested = true; |
a5f1783b VB |
121 | } |
122 | ||
df225c87 | 123 | /* Allocates a hash table via memblock. Can only be used during early boot. */ |
a5f1783b VB |
124 | int __init stack_depot_early_init(void) |
125 | { | |
f9987921 | 126 | unsigned long entries = 0; |
a5f1783b | 127 | |
df225c87 | 128 | /* This function must be called only once, from mm_init(). */ |
a5f1783b VB |
129 | if (WARN_ON(__stack_depot_early_init_passed)) |
130 | return 0; | |
a5f1783b VB |
131 | __stack_depot_early_init_passed = true; |
132 | ||
df225c87 AK |
133 | /* |
134 | * If KASAN is enabled, use the maximum order: KASAN is frequently used | |
135 | * in fuzzing scenarios, which leads to a large number of different | |
136 | * stack traces being stored in stack depot. | |
137 | */ | |
4c2e9a67 AK |
138 | if (kasan_enabled() && !stack_bucket_number_order) |
139 | stack_bucket_number_order = STACK_BUCKET_NUMBER_ORDER_MAX; | |
f9987921 | 140 | |
735df3c3 | 141 | if (!__stack_depot_early_init_requested || stack_depot_disabled) |
a5f1783b VB |
142 | return 0; |
143 | ||
df225c87 | 144 | /* |
4c2e9a67 AK |
145 | * If stack_bucket_number_order is not set, leave entries as 0 to rely |
146 | * on the automatic calculations performed by alloc_large_system_hash. | |
df225c87 | 147 | */ |
4c2e9a67 AK |
148 | if (stack_bucket_number_order) |
149 | entries = 1UL << stack_bucket_number_order; | |
df225c87 | 150 | pr_info("allocating hash table via alloc_large_system_hash\n"); |
f9987921 VB |
151 | stack_table = alloc_large_system_hash("stackdepot", |
152 | sizeof(struct stack_record *), | |
153 | entries, | |
4c2e9a67 | 154 | STACK_HASH_TABLE_SCALE, |
f9987921 VB |
155 | HASH_EARLY | HASH_ZERO, |
156 | NULL, | |
157 | &stack_hash_mask, | |
4c2e9a67 AK |
158 | 1UL << STACK_BUCKET_NUMBER_ORDER_MIN, |
159 | 1UL << STACK_BUCKET_NUMBER_ORDER_MAX); | |
a5f1783b | 160 | if (!stack_table) { |
4a6b5314 | 161 | pr_err("hash table allocation failed, disabling\n"); |
735df3c3 | 162 | stack_depot_disabled = true; |
a5f1783b VB |
163 | return -ENOMEM; |
164 | } | |
165 | ||
166 | return 0; | |
167 | } | |
168 | ||
df225c87 | 169 | /* Allocates a hash table via kvcalloc. Can be used after boot. */ |
a5f1783b | 170 | int stack_depot_init(void) |
e1fdc403 | 171 | { |
2dba5eb1 | 172 | static DEFINE_MUTEX(stack_depot_init_mutex); |
c60324fb | 173 | unsigned long entries; |
a5f1783b | 174 | int ret = 0; |
2dba5eb1 VB |
175 | |
176 | mutex_lock(&stack_depot_init_mutex); | |
f9987921 | 177 | |
c60324fb AK |
178 | if (stack_depot_disabled || stack_table) |
179 | goto out_unlock; | |
f9987921 | 180 | |
c60324fb | 181 | /* |
4c2e9a67 | 182 | * Similarly to stack_depot_early_init, use stack_bucket_number_order |
c60324fb AK |
183 | * if assigned, and rely on automatic scaling otherwise. |
184 | */ | |
4c2e9a67 AK |
185 | if (stack_bucket_number_order) { |
186 | entries = 1UL << stack_bucket_number_order; | |
c60324fb | 187 | } else { |
4c2e9a67 | 188 | int scale = STACK_HASH_TABLE_SCALE; |
c60324fb AK |
189 | |
190 | entries = nr_free_buffer_pages(); | |
191 | entries = roundup_pow_of_two(entries); | |
192 | ||
193 | if (scale > PAGE_SHIFT) | |
194 | entries >>= (scale - PAGE_SHIFT); | |
195 | else | |
196 | entries <<= (PAGE_SHIFT - scale); | |
e1fdc403 | 197 | } |
c60324fb | 198 | |
4c2e9a67 AK |
199 | if (entries < 1UL << STACK_BUCKET_NUMBER_ORDER_MIN) |
200 | entries = 1UL << STACK_BUCKET_NUMBER_ORDER_MIN; | |
201 | if (entries > 1UL << STACK_BUCKET_NUMBER_ORDER_MAX) | |
202 | entries = 1UL << STACK_BUCKET_NUMBER_ORDER_MAX; | |
c60324fb AK |
203 | |
204 | pr_info("allocating hash table of %lu entries via kvcalloc\n", entries); | |
205 | stack_table = kvcalloc(entries, sizeof(struct stack_record *), GFP_KERNEL); | |
206 | if (!stack_table) { | |
207 | pr_err("hash table allocation failed, disabling\n"); | |
208 | stack_depot_disabled = true; | |
209 | ret = -ENOMEM; | |
210 | goto out_unlock; | |
211 | } | |
212 | stack_hash_mask = entries - 1; | |
213 | ||
214 | out_unlock: | |
2dba5eb1 | 215 | mutex_unlock(&stack_depot_init_mutex); |
c60324fb | 216 | |
a5f1783b | 217 | return ret; |
e1fdc403 | 218 | } |
2dba5eb1 | 219 | EXPORT_SYMBOL_GPL(stack_depot_init); |
cd11016e | 220 | |
cd0fc64e | 221 | /* Uses preallocated memory to initialize a new stack depot pool. */ |
514d5c55 | 222 | static void depot_init_pool(void **prealloc) |
15ef6a98 | 223 | { |
15ef6a98 | 224 | /* |
d11a5621 AK |
225 | * If the next pool is already initialized or the maximum number of |
226 | * pools is reached, do not use the preallocated memory. | |
cd0fc64e AK |
227 | * smp_load_acquire() here pairs with smp_store_release() below and |
228 | * in depot_alloc_stack(). | |
15ef6a98 | 229 | */ |
d11a5621 | 230 | if (!smp_load_acquire(&next_pool_required)) |
514d5c55 | 231 | return; |
cd0fc64e AK |
232 | |
233 | /* Check if the current pool is not yet allocated. */ | |
961c949b | 234 | if (stack_pools[pool_index] == NULL) { |
cd0fc64e | 235 | /* Use the preallocated memory for the current pool. */ |
961c949b | 236 | stack_pools[pool_index] = *prealloc; |
15ef6a98 AK |
237 | *prealloc = NULL; |
238 | } else { | |
cd0fc64e AK |
239 | /* |
240 | * Otherwise, use the preallocated memory for the next pool | |
241 | * as long as we do not exceed the maximum number of pools. | |
242 | */ | |
424cafee | 243 | if (pool_index + 1 < DEPOT_MAX_POOLS) { |
961c949b | 244 | stack_pools[pool_index + 1] = *prealloc; |
15ef6a98 AK |
245 | *prealloc = NULL; |
246 | } | |
247 | /* | |
d11a5621 AK |
248 | * At this point, either the next pool is initialized or the |
249 | * maximum number of pools is reached. In either case, take | |
250 | * note that initializing another pool is not required. | |
cd0fc64e AK |
251 | * This smp_store_release pairs with smp_load_acquire() above |
252 | * and in stack_depot_save(). | |
15ef6a98 | 253 | */ |
d11a5621 | 254 | smp_store_release(&next_pool_required, 0); |
15ef6a98 | 255 | } |
15ef6a98 AK |
256 | } |
257 | ||
cd0fc64e | 258 | /* Allocates a new stack in a stack depot pool. */ |
15ef6a98 AK |
259 | static struct stack_record * |
260 | depot_alloc_stack(unsigned long *entries, int size, u32 hash, void **prealloc) | |
261 | { | |
262 | struct stack_record *stack; | |
263 | size_t required_size = struct_size(stack, entries, size); | |
264 | ||
424cafee | 265 | required_size = ALIGN(required_size, 1 << DEPOT_STACK_ALIGN); |
15ef6a98 | 266 | |
cd0fc64e | 267 | /* Check if there is not enough space in the current pool. */ |
424cafee | 268 | if (unlikely(pool_offset + required_size > DEPOT_POOL_SIZE)) { |
cd0fc64e | 269 | /* Bail out if we reached the pool limit. */ |
424cafee | 270 | if (unlikely(pool_index + 1 >= DEPOT_MAX_POOLS)) { |
15ef6a98 AK |
271 | WARN_ONCE(1, "Stack depot reached limit capacity"); |
272 | return NULL; | |
273 | } | |
cd0fc64e | 274 | |
beb3c23c AK |
275 | /* |
276 | * Move on to the next pool. | |
277 | * WRITE_ONCE pairs with potential concurrent read in | |
278 | * stack_depot_fetch(). | |
279 | */ | |
280 | WRITE_ONCE(pool_index, pool_index + 1); | |
961c949b | 281 | pool_offset = 0; |
15ef6a98 | 282 | /* |
d11a5621 AK |
283 | * If the maximum number of pools is not reached, take note |
284 | * that the next pool needs to initialized. | |
cd0fc64e AK |
285 | * smp_store_release() here pairs with smp_load_acquire() in |
286 | * stack_depot_save() and depot_init_pool(). | |
15ef6a98 | 287 | */ |
424cafee | 288 | if (pool_index + 1 < DEPOT_MAX_POOLS) |
d11a5621 | 289 | smp_store_release(&next_pool_required, 1); |
15ef6a98 | 290 | } |
cd0fc64e AK |
291 | |
292 | /* Assign the preallocated memory to a pool if required. */ | |
514d5c55 AK |
293 | if (*prealloc) |
294 | depot_init_pool(prealloc); | |
cd0fc64e AK |
295 | |
296 | /* Check if we have a pool to save the stack trace. */ | |
961c949b | 297 | if (stack_pools[pool_index] == NULL) |
15ef6a98 AK |
298 | return NULL; |
299 | ||
cd0fc64e | 300 | /* Save the stack trace. */ |
961c949b | 301 | stack = stack_pools[pool_index] + pool_offset; |
15ef6a98 AK |
302 | stack->hash = hash; |
303 | stack->size = size; | |
961c949b | 304 | stack->handle.pool_index = pool_index; |
424cafee | 305 | stack->handle.offset = pool_offset >> DEPOT_STACK_ALIGN; |
15ef6a98 AK |
306 | stack->handle.valid = 1; |
307 | stack->handle.extra = 0; | |
308 | memcpy(stack->entries, entries, flex_array_size(stack, entries, size)); | |
961c949b | 309 | pool_offset += required_size; |
8e00b2df AP |
310 | /* |
311 | * Let KMSAN know the stored stack record is initialized. This shall | |
312 | * prevent false positive reports if instrumented code accesses it. | |
313 | */ | |
314 | kmsan_unpoison_memory(stack, required_size); | |
15ef6a98 AK |
315 | |
316 | return stack; | |
317 | } | |
318 | ||
b232b999 | 319 | /* Calculates the hash for a stack. */ |
cd11016e AP |
320 | static inline u32 hash_stack(unsigned long *entries, unsigned int size) |
321 | { | |
322 | return jhash2((u32 *)entries, | |
180644f8 GS |
323 | array_size(size, sizeof(*entries)) / sizeof(u32), |
324 | STACK_HASH_SEED); | |
cd11016e AP |
325 | } |
326 | ||
b232b999 AK |
327 | /* |
328 | * Non-instrumented version of memcmp(). | |
329 | * Does not check the lexicographical order, only the equality. | |
a571b272 AP |
330 | */ |
331 | static inline | |
332 | int stackdepot_memcmp(const unsigned long *u1, const unsigned long *u2, | |
333 | unsigned int n) | |
334 | { | |
335 | for ( ; n-- ; u1++, u2++) { | |
336 | if (*u1 != *u2) | |
337 | return 1; | |
338 | } | |
339 | return 0; | |
340 | } | |
341 | ||
b232b999 | 342 | /* Finds a stack in a bucket of the hash table. */ |
cd11016e AP |
343 | static inline struct stack_record *find_stack(struct stack_record *bucket, |
344 | unsigned long *entries, int size, | |
345 | u32 hash) | |
346 | { | |
347 | struct stack_record *found; | |
348 | ||
349 | for (found = bucket; found; found = found->next) { | |
350 | if (found->hash == hash && | |
351 | found->size == size && | |
a571b272 | 352 | !stackdepot_memcmp(entries, found->entries, size)) |
cd11016e | 353 | return found; |
cd11016e AP |
354 | } |
355 | return NULL; | |
356 | } | |
357 | ||
11ac25c6 ME |
358 | depot_stack_handle_t __stack_depot_save(unsigned long *entries, |
359 | unsigned int nr_entries, | |
360 | gfp_t alloc_flags, bool can_alloc) | |
cd11016e | 361 | { |
cd11016e | 362 | struct stack_record *found = NULL, **bucket; |
83a4f1ef | 363 | union handle_parts retval = { .handle = 0 }; |
cd11016e AP |
364 | struct page *page = NULL; |
365 | void *prealloc = NULL; | |
c0cfc337 TG |
366 | unsigned long flags; |
367 | u32 hash; | |
cd11016e | 368 | |
e9400660 ME |
369 | /* |
370 | * If this stack trace is from an interrupt, including anything before | |
b232b999 | 371 | * interrupt entry usually leads to unbounded stack depot growth. |
e9400660 | 372 | * |
b232b999 AK |
373 | * Since use of filter_irq_stacks() is a requirement to ensure stack |
374 | * depot can efficiently deduplicate interrupt stacks, always | |
375 | * filter_irq_stacks() to simplify all callers' use of stack depot. | |
e9400660 ME |
376 | */ |
377 | nr_entries = filter_irq_stacks(entries, nr_entries); | |
378 | ||
735df3c3 | 379 | if (unlikely(nr_entries == 0) || stack_depot_disabled) |
cd11016e AP |
380 | goto fast_exit; |
381 | ||
c0cfc337 | 382 | hash = hash_stack(entries, nr_entries); |
f9987921 | 383 | bucket = &stack_table[hash & stack_hash_mask]; |
cd11016e AP |
384 | |
385 | /* | |
386 | * Fast path: look the stack trace up without locking. | |
387 | * The smp_load_acquire() here pairs with smp_store_release() to | |
388 | * |bucket| below. | |
389 | */ | |
b232b999 | 390 | found = find_stack(smp_load_acquire(bucket), entries, nr_entries, hash); |
cd11016e AP |
391 | if (found) |
392 | goto exit; | |
393 | ||
394 | /* | |
d11a5621 AK |
395 | * Check if another stack pool needs to be initialized. If so, allocate |
396 | * the memory now - we won't be able to do that under the lock. | |
cd11016e AP |
397 | * |
398 | * The smp_load_acquire() here pairs with smp_store_release() to | |
cb788e84 | 399 | * |next_pool_inited| in depot_alloc_stack() and depot_init_pool(). |
cd11016e | 400 | */ |
d11a5621 | 401 | if (unlikely(can_alloc && smp_load_acquire(&next_pool_required))) { |
cd11016e AP |
402 | /* |
403 | * Zero out zone modifiers, as we don't have specific zone | |
404 | * requirements. Keep the flags related to allocation in atomic | |
405 | * contexts and I/O. | |
406 | */ | |
407 | alloc_flags &= ~GFP_ZONEMASK; | |
408 | alloc_flags &= (GFP_ATOMIC | GFP_KERNEL); | |
87cc271d | 409 | alloc_flags |= __GFP_NOWARN; |
424cafee | 410 | page = alloc_pages(alloc_flags, DEPOT_POOL_ORDER); |
cd11016e AP |
411 | if (page) |
412 | prealloc = page_address(page); | |
413 | } | |
414 | ||
961c949b | 415 | raw_spin_lock_irqsave(&pool_lock, flags); |
cd11016e | 416 | |
c0cfc337 | 417 | found = find_stack(*bucket, entries, nr_entries, hash); |
cd11016e | 418 | if (!found) { |
b232b999 AK |
419 | struct stack_record *new = |
420 | depot_alloc_stack(entries, nr_entries, hash, &prealloc); | |
7f2b8818 | 421 | |
cd11016e AP |
422 | if (new) { |
423 | new->next = *bucket; | |
424 | /* | |
425 | * This smp_store_release() pairs with | |
426 | * smp_load_acquire() from |bucket| above. | |
427 | */ | |
428 | smp_store_release(bucket, new); | |
429 | found = new; | |
430 | } | |
431 | } else if (prealloc) { | |
432 | /* | |
b232b999 AK |
433 | * Stack depot already contains this stack trace, but let's |
434 | * keep the preallocated memory for the future. | |
cd11016e | 435 | */ |
514d5c55 | 436 | depot_init_pool(&prealloc); |
cd11016e AP |
437 | } |
438 | ||
961c949b | 439 | raw_spin_unlock_irqrestore(&pool_lock, flags); |
cd11016e AP |
440 | exit: |
441 | if (prealloc) { | |
b232b999 | 442 | /* Stack depot didn't use this memory, free it. */ |
424cafee | 443 | free_pages((unsigned long)prealloc, DEPOT_POOL_ORDER); |
cd11016e AP |
444 | } |
445 | if (found) | |
83a4f1ef | 446 | retval.handle = found->handle.handle; |
cd11016e | 447 | fast_exit: |
83a4f1ef | 448 | return retval.handle; |
cd11016e | 449 | } |
11ac25c6 ME |
450 | EXPORT_SYMBOL_GPL(__stack_depot_save); |
451 | ||
11ac25c6 ME |
452 | depot_stack_handle_t stack_depot_save(unsigned long *entries, |
453 | unsigned int nr_entries, | |
454 | gfp_t alloc_flags) | |
455 | { | |
36aa1e67 | 456 | return __stack_depot_save(entries, nr_entries, alloc_flags, true); |
11ac25c6 | 457 | } |
c0cfc337 | 458 | EXPORT_SYMBOL_GPL(stack_depot_save); |
15ef6a98 | 459 | |
15ef6a98 AK |
460 | unsigned int stack_depot_fetch(depot_stack_handle_t handle, |
461 | unsigned long **entries) | |
462 | { | |
463 | union handle_parts parts = { .handle = handle }; | |
beb3c23c AK |
464 | /* |
465 | * READ_ONCE pairs with potential concurrent write in | |
466 | * depot_alloc_stack. | |
467 | */ | |
468 | int pool_index_cached = READ_ONCE(pool_index); | |
961c949b | 469 | void *pool; |
424cafee | 470 | size_t offset = parts.offset << DEPOT_STACK_ALIGN; |
15ef6a98 AK |
471 | struct stack_record *stack; |
472 | ||
473 | *entries = NULL; | |
8e00b2df AP |
474 | /* |
475 | * Let KMSAN know *entries is initialized. This shall prevent false | |
476 | * positive reports if instrumented code accesses it. | |
477 | */ | |
478 | kmsan_unpoison_memory(entries, sizeof(*entries)); | |
479 | ||
15ef6a98 AK |
480 | if (!handle) |
481 | return 0; | |
482 | ||
beb3c23c | 483 | if (parts.pool_index > pool_index_cached) { |
961c949b | 484 | WARN(1, "pool index %d out of bounds (%d) for stack id %08x\n", |
beb3c23c | 485 | parts.pool_index, pool_index_cached, handle); |
15ef6a98 AK |
486 | return 0; |
487 | } | |
961c949b AK |
488 | pool = stack_pools[parts.pool_index]; |
489 | if (!pool) | |
15ef6a98 | 490 | return 0; |
961c949b | 491 | stack = pool + offset; |
15ef6a98 AK |
492 | |
493 | *entries = stack->entries; | |
494 | return stack->size; | |
495 | } | |
496 | EXPORT_SYMBOL_GPL(stack_depot_fetch); | |
497 | ||
15ef6a98 AK |
498 | void stack_depot_print(depot_stack_handle_t stack) |
499 | { | |
500 | unsigned long *entries; | |
501 | unsigned int nr_entries; | |
502 | ||
503 | nr_entries = stack_depot_fetch(stack, &entries); | |
504 | if (nr_entries > 0) | |
505 | stack_trace_print(entries, nr_entries, 0); | |
506 | } | |
507 | EXPORT_SYMBOL_GPL(stack_depot_print); | |
508 | ||
15ef6a98 AK |
509 | int stack_depot_snprint(depot_stack_handle_t handle, char *buf, size_t size, |
510 | int spaces) | |
511 | { | |
512 | unsigned long *entries; | |
513 | unsigned int nr_entries; | |
514 | ||
515 | nr_entries = stack_depot_fetch(handle, &entries); | |
516 | return nr_entries ? stack_trace_snprint(buf, size, entries, nr_entries, | |
517 | spaces) : 0; | |
518 | } | |
519 | EXPORT_SYMBOL_GPL(stack_depot_snprint); | |
520 | ||
36aa1e67 AK |
521 | depot_stack_handle_t __must_check stack_depot_set_extra_bits( |
522 | depot_stack_handle_t handle, unsigned int extra_bits) | |
523 | { | |
524 | union handle_parts parts = { .handle = handle }; | |
525 | ||
526 | /* Don't set extra bits on empty handles. */ | |
527 | if (!handle) | |
528 | return 0; | |
529 | ||
530 | parts.extra = extra_bits; | |
531 | return parts.handle; | |
532 | } | |
533 | EXPORT_SYMBOL(stack_depot_set_extra_bits); | |
534 | ||
15ef6a98 AK |
535 | unsigned int stack_depot_get_extra_bits(depot_stack_handle_t handle) |
536 | { | |
537 | union handle_parts parts = { .handle = handle }; | |
538 | ||
539 | return parts.extra; | |
540 | } | |
541 | EXPORT_SYMBOL(stack_depot_get_extra_bits); |