1 // SPDX-License-Identifier: GPL-2.0-only 1 // SPDX-License-Identifier: GPL-2.0-only
2 /* 2 /*
3 * kernel/stacktrace.c 3 * kernel/stacktrace.c
4 * 4 *
5 * Stack trace management functions 5 * Stack trace management functions
6 * 6 *
7 * Copyright (C) 2006 Red Hat, Inc., Ingo Mol 7 * Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
8 */ 8 */
9 #include <linux/sched/task_stack.h> 9 #include <linux/sched/task_stack.h>
10 #include <linux/sched/debug.h> 10 #include <linux/sched/debug.h>
11 #include <linux/sched.h> 11 #include <linux/sched.h>
12 #include <linux/kernel.h> 12 #include <linux/kernel.h>
13 #include <linux/export.h> 13 #include <linux/export.h>
14 #include <linux/kallsyms.h> 14 #include <linux/kallsyms.h>
15 #include <linux/stacktrace.h> 15 #include <linux/stacktrace.h>
16 #include <linux/interrupt.h> <<
17 16
18 /** 17 /**
19 * stack_trace_print - Print the entries in th 18 * stack_trace_print - Print the entries in the stack trace
20 * @entries: Pointer to storage array 19 * @entries: Pointer to storage array
21 * @nr_entries: Number of entries in the stora 20 * @nr_entries: Number of entries in the storage array
22 * @spaces: Number of leading spaces to pr 21 * @spaces: Number of leading spaces to print
23 */ 22 */
24 void stack_trace_print(const unsigned long *en 23 void stack_trace_print(const unsigned long *entries, unsigned int nr_entries,
25 int spaces) 24 int spaces)
26 { 25 {
27 unsigned int i; 26 unsigned int i;
28 27
29 if (WARN_ON(!entries)) 28 if (WARN_ON(!entries))
30 return; 29 return;
31 30
32 for (i = 0; i < nr_entries; i++) 31 for (i = 0; i < nr_entries; i++)
33 printk("%*c%pS\n", 1 + spaces, 32 printk("%*c%pS\n", 1 + spaces, ' ', (void *)entries[i]);
34 } 33 }
35 EXPORT_SYMBOL_GPL(stack_trace_print); 34 EXPORT_SYMBOL_GPL(stack_trace_print);
36 35
37 /** 36 /**
38 * stack_trace_snprint - Print the entries in 37 * stack_trace_snprint - Print the entries in the stack trace into a buffer
39 * @buf: Pointer to the print buffer 38 * @buf: Pointer to the print buffer
40 * @size: Size of the print buffer 39 * @size: Size of the print buffer
41 * @entries: Pointer to storage array 40 * @entries: Pointer to storage array
42 * @nr_entries: Number of entries in the stora 41 * @nr_entries: Number of entries in the storage array
43 * @spaces: Number of leading spaces to pr 42 * @spaces: Number of leading spaces to print
44 * 43 *
45 * Return: Number of bytes printed. 44 * Return: Number of bytes printed.
46 */ 45 */
47 int stack_trace_snprint(char *buf, size_t size 46 int stack_trace_snprint(char *buf, size_t size, const unsigned long *entries,
48 unsigned int nr_entrie 47 unsigned int nr_entries, int spaces)
49 { 48 {
50 unsigned int generated, i, total = 0; 49 unsigned int generated, i, total = 0;
51 50
52 if (WARN_ON(!entries)) 51 if (WARN_ON(!entries))
53 return 0; 52 return 0;
54 53
55 for (i = 0; i < nr_entries && size; i+ 54 for (i = 0; i < nr_entries && size; i++) {
56 generated = snprintf(buf, size 55 generated = snprintf(buf, size, "%*c%pS\n", 1 + spaces, ' ',
57 (void *)e 56 (void *)entries[i]);
58 57
59 total += generated; 58 total += generated;
60 if (generated >= size) { 59 if (generated >= size) {
61 buf += size; 60 buf += size;
62 size = 0; 61 size = 0;
63 } else { 62 } else {
64 buf += generated; 63 buf += generated;
65 size -= generated; 64 size -= generated;
66 } 65 }
67 } 66 }
68 67
69 return total; 68 return total;
70 } 69 }
71 EXPORT_SYMBOL_GPL(stack_trace_snprint); 70 EXPORT_SYMBOL_GPL(stack_trace_snprint);
72 71
73 #ifdef CONFIG_ARCH_STACKWALK 72 #ifdef CONFIG_ARCH_STACKWALK
74 73
75 struct stacktrace_cookie { 74 struct stacktrace_cookie {
76 unsigned long *store; 75 unsigned long *store;
77 unsigned int size; 76 unsigned int size;
78 unsigned int skip; 77 unsigned int skip;
79 unsigned int len; 78 unsigned int len;
80 }; 79 };
81 80
82 static bool stack_trace_consume_entry(void *co 81 static bool stack_trace_consume_entry(void *cookie, unsigned long addr)
83 { 82 {
84 struct stacktrace_cookie *c = cookie; 83 struct stacktrace_cookie *c = cookie;
85 84
86 if (c->len >= c->size) 85 if (c->len >= c->size)
87 return false; 86 return false;
88 87
89 if (c->skip > 0) { 88 if (c->skip > 0) {
90 c->skip--; 89 c->skip--;
91 return true; 90 return true;
92 } 91 }
93 c->store[c->len++] = addr; 92 c->store[c->len++] = addr;
94 return c->len < c->size; 93 return c->len < c->size;
95 } 94 }
96 95
97 static bool stack_trace_consume_entry_nosched( 96 static bool stack_trace_consume_entry_nosched(void *cookie, unsigned long addr)
98 { 97 {
99 if (in_sched_functions(addr)) 98 if (in_sched_functions(addr))
100 return true; 99 return true;
101 return stack_trace_consume_entry(cooki 100 return stack_trace_consume_entry(cookie, addr);
102 } 101 }
103 102
104 /** 103 /**
105 * stack_trace_save - Save a stack trace into 104 * stack_trace_save - Save a stack trace into a storage array
106 * @store: Pointer to storage array 105 * @store: Pointer to storage array
107 * @size: Size of the storage array 106 * @size: Size of the storage array
108 * @skipnr: Number of entries to skip at t 107 * @skipnr: Number of entries to skip at the start of the stack trace
109 * 108 *
110 * Return: Number of trace entries stored. 109 * Return: Number of trace entries stored.
111 */ 110 */
112 unsigned int stack_trace_save(unsigned long *s 111 unsigned int stack_trace_save(unsigned long *store, unsigned int size,
113 unsigned int ski 112 unsigned int skipnr)
114 { 113 {
115 stack_trace_consume_fn consume_entry = 114 stack_trace_consume_fn consume_entry = stack_trace_consume_entry;
116 struct stacktrace_cookie c = { 115 struct stacktrace_cookie c = {
117 .store = store, 116 .store = store,
118 .size = size, 117 .size = size,
119 .skip = skipnr + 1, 118 .skip = skipnr + 1,
120 }; 119 };
121 120
122 arch_stack_walk(consume_entry, &c, cur 121 arch_stack_walk(consume_entry, &c, current, NULL);
123 return c.len; 122 return c.len;
124 } 123 }
125 EXPORT_SYMBOL_GPL(stack_trace_save); 124 EXPORT_SYMBOL_GPL(stack_trace_save);
126 125
127 /** 126 /**
128 * stack_trace_save_tsk - Save a task stack tr 127 * stack_trace_save_tsk - Save a task stack trace into a storage array
129 * @tsk: The task to examine !! 128 * @task: The task to examine
130 * @store: Pointer to storage array 129 * @store: Pointer to storage array
131 * @size: Size of the storage array 130 * @size: Size of the storage array
132 * @skipnr: Number of entries to skip at t 131 * @skipnr: Number of entries to skip at the start of the stack trace
133 * 132 *
134 * Return: Number of trace entries stored. 133 * Return: Number of trace entries stored.
135 */ 134 */
136 unsigned int stack_trace_save_tsk(struct task_ 135 unsigned int stack_trace_save_tsk(struct task_struct *tsk, unsigned long *store,
137 unsigned int 136 unsigned int size, unsigned int skipnr)
138 { 137 {
139 stack_trace_consume_fn consume_entry = 138 stack_trace_consume_fn consume_entry = stack_trace_consume_entry_nosched;
140 struct stacktrace_cookie c = { 139 struct stacktrace_cookie c = {
141 .store = store, 140 .store = store,
142 .size = size, 141 .size = size,
143 /* skip this function if they 142 /* skip this function if they are tracing us */
144 .skip = skipnr + (current == 143 .skip = skipnr + (current == tsk),
145 }; 144 };
146 145
147 if (!try_get_task_stack(tsk)) 146 if (!try_get_task_stack(tsk))
148 return 0; 147 return 0;
149 148
150 arch_stack_walk(consume_entry, &c, tsk 149 arch_stack_walk(consume_entry, &c, tsk, NULL);
151 put_task_stack(tsk); 150 put_task_stack(tsk);
152 return c.len; 151 return c.len;
153 } 152 }
154 EXPORT_SYMBOL_GPL(stack_trace_save_tsk); <<
155 153
156 /** 154 /**
157 * stack_trace_save_regs - Save a stack trace 155 * stack_trace_save_regs - Save a stack trace based on pt_regs into a storage array
158 * @regs: Pointer to pt_regs to examine 156 * @regs: Pointer to pt_regs to examine
159 * @store: Pointer to storage array 157 * @store: Pointer to storage array
160 * @size: Size of the storage array 158 * @size: Size of the storage array
161 * @skipnr: Number of entries to skip at t 159 * @skipnr: Number of entries to skip at the start of the stack trace
162 * 160 *
163 * Return: Number of trace entries stored. 161 * Return: Number of trace entries stored.
164 */ 162 */
165 unsigned int stack_trace_save_regs(struct pt_r 163 unsigned int stack_trace_save_regs(struct pt_regs *regs, unsigned long *store,
166 unsigned in 164 unsigned int size, unsigned int skipnr)
167 { 165 {
168 stack_trace_consume_fn consume_entry = 166 stack_trace_consume_fn consume_entry = stack_trace_consume_entry;
169 struct stacktrace_cookie c = { 167 struct stacktrace_cookie c = {
170 .store = store, 168 .store = store,
171 .size = size, 169 .size = size,
172 .skip = skipnr, 170 .skip = skipnr,
173 }; 171 };
174 172
175 arch_stack_walk(consume_entry, &c, cur 173 arch_stack_walk(consume_entry, &c, current, regs);
176 return c.len; 174 return c.len;
177 } 175 }
178 176
179 #ifdef CONFIG_HAVE_RELIABLE_STACKTRACE 177 #ifdef CONFIG_HAVE_RELIABLE_STACKTRACE
180 /** 178 /**
181 * stack_trace_save_tsk_reliable - Save task s 179 * stack_trace_save_tsk_reliable - Save task stack with verification
182 * @tsk: Pointer to the task to examine 180 * @tsk: Pointer to the task to examine
183 * @store: Pointer to storage array 181 * @store: Pointer to storage array
184 * @size: Size of the storage array 182 * @size: Size of the storage array
185 * 183 *
186 * Return: An error if it detects any unr 184 * Return: An error if it detects any unreliable features of the
187 * stack. Otherwise it guarantees 185 * stack. Otherwise it guarantees that the stack trace is
188 * reliable and returns the numbe 186 * reliable and returns the number of entries stored.
189 * 187 *
190 * If the task is not 'current', the caller *m 188 * If the task is not 'current', the caller *must* ensure the task is inactive.
191 */ 189 */
192 int stack_trace_save_tsk_reliable(struct task_ 190 int stack_trace_save_tsk_reliable(struct task_struct *tsk, unsigned long *store,
193 unsigned int 191 unsigned int size)
194 { 192 {
195 stack_trace_consume_fn consume_entry = 193 stack_trace_consume_fn consume_entry = stack_trace_consume_entry;
196 struct stacktrace_cookie c = { 194 struct stacktrace_cookie c = {
197 .store = store, 195 .store = store,
198 .size = size, 196 .size = size,
199 }; 197 };
200 int ret; 198 int ret;
201 199
202 /* 200 /*
203 * If the task doesn't have a stack (e 201 * If the task doesn't have a stack (e.g., a zombie), the stack is
204 * "reliably" empty. 202 * "reliably" empty.
205 */ 203 */
206 if (!try_get_task_stack(tsk)) 204 if (!try_get_task_stack(tsk))
207 return 0; 205 return 0;
208 206
209 ret = arch_stack_walk_reliable(consume 207 ret = arch_stack_walk_reliable(consume_entry, &c, tsk);
210 put_task_stack(tsk); 208 put_task_stack(tsk);
211 return ret ? ret : c.len; 209 return ret ? ret : c.len;
212 } 210 }
213 #endif 211 #endif
214 212
215 #ifdef CONFIG_USER_STACKTRACE_SUPPORT 213 #ifdef CONFIG_USER_STACKTRACE_SUPPORT
216 /** 214 /**
217 * stack_trace_save_user - Save a user space s 215 * stack_trace_save_user - Save a user space stack trace into a storage array
218 * @store: Pointer to storage array 216 * @store: Pointer to storage array
219 * @size: Size of the storage array 217 * @size: Size of the storage array
220 * 218 *
221 * Return: Number of trace entries stored. 219 * Return: Number of trace entries stored.
222 */ 220 */
223 unsigned int stack_trace_save_user(unsigned lo 221 unsigned int stack_trace_save_user(unsigned long *store, unsigned int size)
224 { 222 {
225 stack_trace_consume_fn consume_entry = 223 stack_trace_consume_fn consume_entry = stack_trace_consume_entry;
226 struct stacktrace_cookie c = { 224 struct stacktrace_cookie c = {
227 .store = store, 225 .store = store,
228 .size = size, 226 .size = size,
229 }; 227 };
>> 228 mm_segment_t fs;
230 229
231 /* Trace user stack if not a kernel th 230 /* Trace user stack if not a kernel thread */
232 if (current->flags & PF_KTHREAD) 231 if (current->flags & PF_KTHREAD)
233 return 0; 232 return 0;
234 233
>> 234 fs = force_uaccess_begin();
235 arch_stack_walk_user(consume_entry, &c 235 arch_stack_walk_user(consume_entry, &c, task_pt_regs(current));
>> 236 force_uaccess_end(fs);
236 237
237 return c.len; 238 return c.len;
238 } 239 }
239 #endif 240 #endif
240 241
241 #else /* CONFIG_ARCH_STACKWALK */ 242 #else /* CONFIG_ARCH_STACKWALK */
242 243
243 /* 244 /*
244 * Architectures that do not implement save_st 245 * Architectures that do not implement save_stack_trace_*()
245 * get these weak aliases and once-per-bootup 246 * get these weak aliases and once-per-bootup warnings
246 * (whenever this facility is utilized - for e 247 * (whenever this facility is utilized - for example by procfs):
247 */ 248 */
248 __weak void 249 __weak void
249 save_stack_trace_tsk(struct task_struct *tsk, 250 save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
250 { 251 {
251 WARN_ONCE(1, KERN_INFO "save_stack_tra 252 WARN_ONCE(1, KERN_INFO "save_stack_trace_tsk() not implemented yet.\n");
252 } 253 }
253 254
254 __weak void 255 __weak void
255 save_stack_trace_regs(struct pt_regs *regs, st 256 save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
256 { 257 {
257 WARN_ONCE(1, KERN_INFO "save_stack_tra 258 WARN_ONCE(1, KERN_INFO "save_stack_trace_regs() not implemented yet.\n");
258 } 259 }
259 260
260 /** 261 /**
261 * stack_trace_save - Save a stack trace into 262 * stack_trace_save - Save a stack trace into a storage array
262 * @store: Pointer to storage array 263 * @store: Pointer to storage array
263 * @size: Size of the storage array 264 * @size: Size of the storage array
264 * @skipnr: Number of entries to skip at t 265 * @skipnr: Number of entries to skip at the start of the stack trace
265 * 266 *
266 * Return: Number of trace entries stored 267 * Return: Number of trace entries stored
267 */ 268 */
268 unsigned int stack_trace_save(unsigned long *s 269 unsigned int stack_trace_save(unsigned long *store, unsigned int size,
269 unsigned int ski 270 unsigned int skipnr)
270 { 271 {
271 struct stack_trace trace = { 272 struct stack_trace trace = {
272 .entries = store, 273 .entries = store,
273 .max_entries = size, 274 .max_entries = size,
274 .skip = skipnr + 1, 275 .skip = skipnr + 1,
275 }; 276 };
276 277
277 save_stack_trace(&trace); 278 save_stack_trace(&trace);
278 return trace.nr_entries; 279 return trace.nr_entries;
279 } 280 }
280 EXPORT_SYMBOL_GPL(stack_trace_save); 281 EXPORT_SYMBOL_GPL(stack_trace_save);
281 282
282 /** 283 /**
283 * stack_trace_save_tsk - Save a task stack tr 284 * stack_trace_save_tsk - Save a task stack trace into a storage array
284 * @task: The task to examine 285 * @task: The task to examine
285 * @store: Pointer to storage array 286 * @store: Pointer to storage array
286 * @size: Size of the storage array 287 * @size: Size of the storage array
287 * @skipnr: Number of entries to skip at t 288 * @skipnr: Number of entries to skip at the start of the stack trace
288 * 289 *
289 * Return: Number of trace entries stored 290 * Return: Number of trace entries stored
290 */ 291 */
291 unsigned int stack_trace_save_tsk(struct task_ 292 unsigned int stack_trace_save_tsk(struct task_struct *task,
292 unsigned lon 293 unsigned long *store, unsigned int size,
293 unsigned int 294 unsigned int skipnr)
294 { 295 {
295 struct stack_trace trace = { 296 struct stack_trace trace = {
296 .entries = store, 297 .entries = store,
297 .max_entries = size, 298 .max_entries = size,
298 /* skip this function if they 299 /* skip this function if they are tracing us */
299 .skip = skipnr + (current == 300 .skip = skipnr + (current == task),
300 }; 301 };
301 302
302 save_stack_trace_tsk(task, &trace); 303 save_stack_trace_tsk(task, &trace);
303 return trace.nr_entries; 304 return trace.nr_entries;
304 } 305 }
305 EXPORT_SYMBOL_GPL(stack_trace_save_tsk); <<
306 306
307 /** 307 /**
308 * stack_trace_save_regs - Save a stack trace 308 * stack_trace_save_regs - Save a stack trace based on pt_regs into a storage array
309 * @regs: Pointer to pt_regs to examine 309 * @regs: Pointer to pt_regs to examine
310 * @store: Pointer to storage array 310 * @store: Pointer to storage array
311 * @size: Size of the storage array 311 * @size: Size of the storage array
312 * @skipnr: Number of entries to skip at t 312 * @skipnr: Number of entries to skip at the start of the stack trace
313 * 313 *
314 * Return: Number of trace entries stored 314 * Return: Number of trace entries stored
315 */ 315 */
316 unsigned int stack_trace_save_regs(struct pt_r 316 unsigned int stack_trace_save_regs(struct pt_regs *regs, unsigned long *store,
317 unsigned in 317 unsigned int size, unsigned int skipnr)
318 { 318 {
319 struct stack_trace trace = { 319 struct stack_trace trace = {
320 .entries = store, 320 .entries = store,
321 .max_entries = size, 321 .max_entries = size,
322 .skip = skipnr, 322 .skip = skipnr,
323 }; 323 };
324 324
325 save_stack_trace_regs(regs, &trace); 325 save_stack_trace_regs(regs, &trace);
326 return trace.nr_entries; 326 return trace.nr_entries;
327 } 327 }
328 328
329 #ifdef CONFIG_HAVE_RELIABLE_STACKTRACE 329 #ifdef CONFIG_HAVE_RELIABLE_STACKTRACE
330 /** 330 /**
331 * stack_trace_save_tsk_reliable - Save task s 331 * stack_trace_save_tsk_reliable - Save task stack with verification
332 * @tsk: Pointer to the task to examine 332 * @tsk: Pointer to the task to examine
333 * @store: Pointer to storage array 333 * @store: Pointer to storage array
334 * @size: Size of the storage array 334 * @size: Size of the storage array
335 * 335 *
336 * Return: An error if it detects any unr 336 * Return: An error if it detects any unreliable features of the
337 * stack. Otherwise it guarantees 337 * stack. Otherwise it guarantees that the stack trace is
338 * reliable and returns the numbe 338 * reliable and returns the number of entries stored.
339 * 339 *
340 * If the task is not 'current', the caller *m 340 * If the task is not 'current', the caller *must* ensure the task is inactive.
341 */ 341 */
342 int stack_trace_save_tsk_reliable(struct task_ 342 int stack_trace_save_tsk_reliable(struct task_struct *tsk, unsigned long *store,
343 unsigned int 343 unsigned int size)
344 { 344 {
345 struct stack_trace trace = { 345 struct stack_trace trace = {
346 .entries = store, 346 .entries = store,
347 .max_entries = size, 347 .max_entries = size,
348 }; 348 };
349 int ret = save_stack_trace_tsk_reliabl 349 int ret = save_stack_trace_tsk_reliable(tsk, &trace);
350 350
351 return ret ? ret : trace.nr_entries; 351 return ret ? ret : trace.nr_entries;
352 } 352 }
353 #endif 353 #endif
354 354
355 #ifdef CONFIG_USER_STACKTRACE_SUPPORT 355 #ifdef CONFIG_USER_STACKTRACE_SUPPORT
356 /** 356 /**
357 * stack_trace_save_user - Save a user space s 357 * stack_trace_save_user - Save a user space stack trace into a storage array
358 * @store: Pointer to storage array 358 * @store: Pointer to storage array
359 * @size: Size of the storage array 359 * @size: Size of the storage array
360 * 360 *
361 * Return: Number of trace entries stored 361 * Return: Number of trace entries stored
362 */ 362 */
363 unsigned int stack_trace_save_user(unsigned lo 363 unsigned int stack_trace_save_user(unsigned long *store, unsigned int size)
364 { 364 {
365 struct stack_trace trace = { 365 struct stack_trace trace = {
366 .entries = store, 366 .entries = store,
367 .max_entries = size, 367 .max_entries = size,
368 }; 368 };
369 369
370 save_stack_trace_user(&trace); 370 save_stack_trace_user(&trace);
371 return trace.nr_entries; 371 return trace.nr_entries;
372 } 372 }
373 #endif /* CONFIG_USER_STACKTRACE_SUPPORT */ 373 #endif /* CONFIG_USER_STACKTRACE_SUPPORT */
374 374
375 #endif /* !CONFIG_ARCH_STACKWALK */ 375 #endif /* !CONFIG_ARCH_STACKWALK */
376 <<
377 static inline bool in_irqentry_text(unsigned l <<
378 { <<
379 return (ptr >= (unsigned long)&__irqen <<
380 ptr < (unsigned long)&__irqent <<
381 (ptr >= (unsigned long)&__soft <<
382 ptr < (unsigned long)&__softi <<
383 } <<
384 <<
385 /** <<
386 * filter_irq_stacks - Find first IRQ stack en <<
387 * @entries: Pointer to stack trace array <<
388 * @nr_entries: Number of entries in the stora <<
389 * <<
390 * Return: Number of trace entries until IRQ s <<
391 */ <<
392 unsigned int filter_irq_stacks(unsigned long * <<
393 { <<
394 unsigned int i; <<
395 <<
396 for (i = 0; i < nr_entries; i++) { <<
397 if (in_irqentry_text(entries[i <<
398 /* Include the irqentr <<
399 return i + 1; <<
400 } <<
401 } <<
402 return nr_entries; <<
403 } <<
404 EXPORT_SYMBOL_GPL(filter_irq_stacks); <<
405 376
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