projects/linux·blob v5.2-rc4 · refs

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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 <[email protected]>
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 */
23void 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}
34EXPORT_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 */
46int 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}
70EXPORT_SYMBOL_GPL(stack_trace_snprint);
71
72#ifdef CONFIG_ARCH_STACKWALK
73
74struct stacktrace_cookie {
75 unsigned long *store;
76 unsigned int size;
77 unsigned int skip;
78 unsigned int len;
79};
80
81static 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
97static 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 */
113unsigned 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}
126EXPORT_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 */
137unsigned 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 */
164unsigned 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 */
191int 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 */
222unsigned 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
247save_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
253save_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
259save_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 */
274unsigned 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}
286EXPORT_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 */
297unsigned 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 */
320unsigned 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 */
346int 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 */
367unsigned 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 */