projects/linux·blob v5.2-rc1 · refs

378 lines · 9.6 KiB

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