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