1 // SPDX-License-Identifier: GPL-2.0-only
5 * Stack trace management functions
7 * Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
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>
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
23 void stack_trace_print(unsigned long *entries, unsigned int nr_entries,
28 if (WARN_ON(!entries))
31 for (i = 0; i < nr_entries; i++)
32 printk("%*c%pS\n", 1 + spaces, ' ', (void *)entries[i]);
34 EXPORT_SYMBOL_GPL(stack_trace_print);
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
44 * Return: Number of bytes printed.
46 int stack_trace_snprint(char *buf, size_t size, unsigned long *entries,
47 unsigned int nr_entries, int spaces)
49 unsigned int generated, i, total = 0;
51 if (WARN_ON(!entries))
54 for (i = 0; i < nr_entries && size; i++) {
55 generated = snprintf(buf, size, "%*c%pS\n", 1 + spaces, ' ',
59 if (generated >= size) {
70 EXPORT_SYMBOL_GPL(stack_trace_snprint);
72 #ifdef CONFIG_ARCH_STACKWALK
74 struct stacktrace_cookie {
81 static bool stack_trace_consume_entry(void *cookie, unsigned long addr,
84 struct stacktrace_cookie *c = cookie;
86 if (c->len >= c->size)
93 c->store[c->len++] = addr;
94 return c->len < c->size;
97 static bool stack_trace_consume_entry_nosched(void *cookie, unsigned long addr,
100 if (in_sched_functions(addr))
102 return stack_trace_consume_entry(cookie, addr, reliable);
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
111 * Return: Number of trace entries stored.
113 unsigned int stack_trace_save(unsigned long *store, unsigned int size,
116 stack_trace_consume_fn consume_entry = stack_trace_consume_entry;
117 struct stacktrace_cookie c = {
123 arch_stack_walk(consume_entry, &c, current, NULL);
126 EXPORT_SYMBOL_GPL(stack_trace_save);
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
135 * Return: Number of trace entries stored.
137 unsigned int stack_trace_save_tsk(struct task_struct *tsk, unsigned long *store,
138 unsigned int size, unsigned int skipnr)
140 stack_trace_consume_fn consume_entry = stack_trace_consume_entry_nosched;
141 struct stacktrace_cookie c = {
147 if (!try_get_task_stack(tsk))
150 arch_stack_walk(consume_entry, &c, tsk, NULL);
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
162 * Return: Number of trace entries stored.
164 unsigned int stack_trace_save_regs(struct pt_regs *regs, unsigned long *store,
165 unsigned int size, unsigned int skipnr)
167 stack_trace_consume_fn consume_entry = stack_trace_consume_entry;
168 struct stacktrace_cookie c = {
174 arch_stack_walk(consume_entry, &c, current, regs);
178 #ifdef CONFIG_HAVE_RELIABLE_STACKTRACE
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
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.
189 * If the task is not 'current', the caller *must* ensure the task is inactive.
191 int stack_trace_save_tsk_reliable(struct task_struct *tsk, unsigned long *store,
194 stack_trace_consume_fn consume_entry = stack_trace_consume_entry;
195 struct stacktrace_cookie c = {
202 * If the task doesn't have a stack (e.g., a zombie), the stack is
205 if (!try_get_task_stack(tsk))
208 ret = arch_stack_walk_reliable(consume_entry, &c, tsk);
214 #ifdef CONFIG_USER_STACKTRACE_SUPPORT
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
220 * Return: Number of trace entries stored.
222 unsigned int stack_trace_save_user(unsigned long *store, unsigned int size)
224 stack_trace_consume_fn consume_entry = stack_trace_consume_entry;
225 struct stacktrace_cookie c = {
230 /* Trace user stack if not a kernel thread */
234 arch_stack_walk_user(consume_entry, &c, task_pt_regs(current));
239 #else /* CONFIG_ARCH_STACKWALK */
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):
247 save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
249 WARN_ONCE(1, KERN_INFO "save_stack_trace_tsk() not implemented yet.\n");
253 save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
255 WARN_ONCE(1, KERN_INFO "save_stack_trace_regs() not implemented yet.\n");
259 save_stack_trace_tsk_reliable(struct task_struct *tsk,
260 struct stack_trace *trace)
262 WARN_ONCE(1, KERN_INFO "save_stack_tsk_reliable() not implemented yet.\n");
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
272 * Return: Number of trace entries stored
274 unsigned int stack_trace_save(unsigned long *store, unsigned int size,
277 struct stack_trace trace = {
283 save_stack_trace(&trace);
284 return trace.nr_entries;
286 EXPORT_SYMBOL_GPL(stack_trace_save);
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
295 * Return: Number of trace entries stored
297 unsigned int stack_trace_save_tsk(struct task_struct *task,
298 unsigned long *store, unsigned int size,
301 struct stack_trace trace = {
307 save_stack_trace_tsk(task, &trace);
308 return trace.nr_entries;
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
318 * Return: Number of trace entries stored
320 unsigned int stack_trace_save_regs(struct pt_regs *regs, unsigned long *store,
321 unsigned int size, unsigned int skipnr)
323 struct stack_trace trace = {
329 save_stack_trace_regs(regs, &trace);
330 return trace.nr_entries;
333 #ifdef CONFIG_HAVE_RELIABLE_STACKTRACE
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
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.
344 * If the task is not 'current', the caller *must* ensure the task is inactive.
346 int stack_trace_save_tsk_reliable(struct task_struct *tsk, unsigned long *store,
349 struct stack_trace trace = {
353 int ret = save_stack_trace_tsk_reliable(tsk, &trace);
355 return ret ? ret : trace.nr_entries;
359 #ifdef CONFIG_USER_STACKTRACE_SUPPORT
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
365 * Return: Number of trace entries stored
367 unsigned int stack_trace_save_user(unsigned long *store, unsigned int size)
369 struct stack_trace trace = {
374 save_stack_trace_user(&trace);
375 return trace.nr_entries;
377 #endif /* CONFIG_USER_STACKTRACE_SUPPORT */
379 #endif /* !CONFIG_ARCH_STACKWALK */