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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 <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 */
24void 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}
35EXPORT_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 */
47int 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}
71EXPORT_SYMBOL_GPL(stack_trace_snprint);
72
73#ifdef CONFIG_ARCH_STACKWALK
74
75struct stacktrace_cookie {
76 unsigned long *store;
77 unsigned int size;
78 unsigned int skip;
79 unsigned int len;
80};
81
82static 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
97static 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 */
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 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 */
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->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
248save_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
254save_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 */
267unsigned 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}
279EXPORT_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 */
290unsigned 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 */
314unsigned 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 */
340int 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 */
361unsigned 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
375static 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 */
390unsigned 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}
402EXPORT_SYMBOL_GPL(filter_irq_stacks);
1/*
2 * kernel/stacktrace.c
3 *
4 * Stack trace management functions
5 *
6 * Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
7 */
8#include <linux/sched.h>
9#include <linux/kernel.h>
10#include <linux/export.h>
11#include <linux/kallsyms.h>
12#include <linux/stacktrace.h>
13
14void print_stack_trace(struct stack_trace *trace, int spaces)
15{
16 int i;
17
18 if (WARN_ON(!trace->entries))
19 return;
20
21 for (i = 0; i < trace->nr_entries; i++) {
22 printk("%*c", 1 + spaces, ' ');
23 print_ip_sym(trace->entries[i]);
24 }
25}
26EXPORT_SYMBOL_GPL(print_stack_trace);
27
28/*
29 * Architectures that do not implement save_stack_trace_tsk or
30 * save_stack_trace_regs get this weak alias and a once-per-bootup warning
31 * (whenever this facility is utilized - for example by procfs):
32 */
33__weak void
34save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
35{
36 WARN_ONCE(1, KERN_INFO "save_stack_trace_tsk() not implemented yet.\n");
37}
38
39__weak void
40save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
41{
42 WARN_ONCE(1, KERN_INFO "save_stack_trace_regs() not implemented yet.\n");
43}