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 17 /** 18 * stack_trace_print - Print the entries in the stack trace 19 * @entries: Pointer to storage array 20 * @nr_entries: Number of entries in the storage array 21 * @spaces: Number of leading spaces to print 22 */ 23 void stack_trace_print(unsigned long *entries, unsigned int nr_entries, 24 int spaces) 25 { 26 unsigned int i; 27 28 if (WARN_ON(!entries)) 29 return; 30 31 for (i = 0; i < nr_entries; i++) 32 printk("%*c%pS\n", 1 + spaces, ' ', (void *)entries[i]); 33 } 34 EXPORT_SYMBOL_GPL(stack_trace_print); 35 36 /** 37 * stack_trace_snprint - Print the entries in the stack trace into a buffer 38 * @buf: Pointer to the print buffer 39 * @size: Size of the print buffer 40 * @entries: Pointer to storage array 41 * @nr_entries: Number of entries in the storage array 42 * @spaces: Number of leading spaces to print 43 * 44 * Return: Number of bytes printed. 45 */ 46 int stack_trace_snprint(char *buf, size_t size, unsigned long *entries, 47 unsigned int nr_entries, int spaces) 48 { 49 unsigned int generated, i, total = 0; 50 51 if (WARN_ON(!entries)) 52 return 0; 53 54 for (i = 0; i < nr_entries && size; i++) { 55 generated = snprintf(buf, size, "%*c%pS\n", 1 + spaces, ' ', 56 (void *)entries[i]); 57 58 total += generated; 59 if (generated >= size) { 60 buf += size; 61 size = 0; 62 } else { 63 buf += generated; 64 size -= generated; 65 } 66 } 67 68 return total; 69 } 70 EXPORT_SYMBOL_GPL(stack_trace_snprint); 71 72 #ifdef CONFIG_ARCH_STACKWALK 73 74 struct stacktrace_cookie { 75 unsigned long *store; 76 unsigned int size; 77 unsigned int skip; 78 unsigned int len; 79 }; 80 81 static bool stack_trace_consume_entry(void *cookie, unsigned long addr, 82 bool reliable) 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 bool reliable) 99 { 100 if (in_sched_functions(addr)) 101 return true; 102 return stack_trace_consume_entry(cookie, addr, reliable); 103 } 104 105 /** 106 * stack_trace_save - Save a stack trace into a storage array 107 * @store: Pointer to storage array 108 * @size: Size of the storage array 109 * @skipnr: Number of entries to skip at the start of the stack trace 110 * 111 * Return: Number of trace entries stored. 112 */ 113 unsigned int stack_trace_save(unsigned long *store, unsigned int size, 114 unsigned int skipnr) 115 { 116 stack_trace_consume_fn consume_entry = stack_trace_consume_entry; 117 struct stacktrace_cookie c = { 118 .store = store, 119 .size = size, 120 .skip = skipnr + 1, 121 }; 122 123 arch_stack_walk(consume_entry, &c, current, NULL); 124 return c.len; 125 } 126 EXPORT_SYMBOL_GPL(stack_trace_save); 127 128 /** 129 * stack_trace_save_tsk - Save a task stack trace into a storage array 130 * @task: The task to examine 131 * @store: Pointer to storage array 132 * @size: Size of the storage array 133 * @skipnr: Number of entries to skip at the start of the stack trace 134 * 135 * Return: Number of trace entries stored. 136 */ 137 unsigned int stack_trace_save_tsk(struct task_struct *tsk, unsigned long *store, 138 unsigned int size, unsigned int skipnr) 139 { 140 stack_trace_consume_fn consume_entry = stack_trace_consume_entry_nosched; 141 struct stacktrace_cookie c = { 142 .store = store, 143 .size = size, 144 .skip = skipnr + 1, 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->mm) 232 return 0; 233 234 arch_stack_walk_user(consume_entry, &c, task_pt_regs(current)); 235 return c.len; 236 } 237 #endif 238 239 #else /* CONFIG_ARCH_STACKWALK */ 240 241 /* 242 * Architectures that do not implement save_stack_trace_*() 243 * get these weak aliases and once-per-bootup warnings 244 * (whenever this facility is utilized - for example by procfs): 245 */ 246 __weak void 247 save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) 248 { 249 WARN_ONCE(1, KERN_INFO "save_stack_trace_tsk() not implemented yet.\n"); 250 } 251 252 __weak void 253 save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace) 254 { 255 WARN_ONCE(1, KERN_INFO "save_stack_trace_regs() not implemented yet.\n"); 256 } 257 258 __weak int 259 save_stack_trace_tsk_reliable(struct task_struct *tsk, 260 struct stack_trace *trace) 261 { 262 WARN_ONCE(1, KERN_INFO "save_stack_tsk_reliable() not implemented yet.\n"); 263 return -ENOSYS; 264 } 265 266 /** 267 * stack_trace_save - Save a stack trace into a storage array 268 * @store: Pointer to storage array 269 * @size: Size of the storage array 270 * @skipnr: Number of entries to skip at the start of the stack trace 271 * 272 * Return: Number of trace entries stored 273 */ 274 unsigned int stack_trace_save(unsigned long *store, unsigned int size, 275 unsigned int skipnr) 276 { 277 struct stack_trace trace = { 278 .entries = store, 279 .max_entries = size, 280 .skip = skipnr + 1, 281 }; 282 283 save_stack_trace(&trace); 284 return trace.nr_entries; 285 } 286 EXPORT_SYMBOL_GPL(stack_trace_save); 287 288 /** 289 * stack_trace_save_tsk - Save a task stack trace into a storage array 290 * @task: The task to examine 291 * @store: Pointer to storage array 292 * @size: Size of the storage array 293 * @skipnr: Number of entries to skip at the start of the stack trace 294 * 295 * Return: Number of trace entries stored 296 */ 297 unsigned int stack_trace_save_tsk(struct task_struct *task, 298 unsigned long *store, unsigned int size, 299 unsigned int skipnr) 300 { 301 struct stack_trace trace = { 302 .entries = store, 303 .max_entries = size, 304 .skip = skipnr + 1, 305 }; 306 307 save_stack_trace_tsk(task, &trace); 308 return trace.nr_entries; 309 } 310 311 /** 312 * stack_trace_save_regs - Save a stack trace based on pt_regs into a storage array 313 * @regs: Pointer to pt_regs to examine 314 * @store: Pointer to storage array 315 * @size: Size of the storage array 316 * @skipnr: Number of entries to skip at the start of the stack trace 317 * 318 * Return: Number of trace entries stored 319 */ 320 unsigned int stack_trace_save_regs(struct pt_regs *regs, unsigned long *store, 321 unsigned int size, unsigned int skipnr) 322 { 323 struct stack_trace trace = { 324 .entries = store, 325 .max_entries = size, 326 .skip = skipnr, 327 }; 328 329 save_stack_trace_regs(regs, &trace); 330 return trace.nr_entries; 331 } 332 333 #ifdef CONFIG_HAVE_RELIABLE_STACKTRACE 334 /** 335 * stack_trace_save_tsk_reliable - Save task stack with verification 336 * @tsk: Pointer to the task to examine 337 * @store: Pointer to storage array 338 * @size: Size of the storage array 339 * 340 * Return: An error if it detects any unreliable features of the 341 * stack. Otherwise it guarantees that the stack trace is 342 * reliable and returns the number of entries stored. 343 * 344 * If the task is not 'current', the caller *must* ensure the task is inactive. 345 */ 346 int stack_trace_save_tsk_reliable(struct task_struct *tsk, unsigned long *store, 347 unsigned int size) 348 { 349 struct stack_trace trace = { 350 .entries = store, 351 .max_entries = size, 352 }; 353 int ret = save_stack_trace_tsk_reliable(tsk, &trace); 354 355 return ret ? ret : trace.nr_entries; 356 } 357 #endif 358 359 #ifdef CONFIG_USER_STACKTRACE_SUPPORT 360 /** 361 * stack_trace_save_user - Save a user space stack trace into a storage array 362 * @store: Pointer to storage array 363 * @size: Size of the storage array 364 * 365 * Return: Number of trace entries stored 366 */ 367 unsigned int stack_trace_save_user(unsigned long *store, unsigned int size) 368 { 369 struct stack_trace trace = { 370 .entries = store, 371 .max_entries = size, 372 }; 373 374 save_stack_trace_user(&trace); 375 return trace.nr_entries; 376 } 377 #endif /* CONFIG_USER_STACKTRACE_SUPPORT */ 378 379 #endif /* !CONFIG_ARCH_STACKWALK */ 380