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bcea3f96 | 1 | // SPDX-License-Identifier: GPL-2.0 |
1427cdf0 LJ |
2 | /* |
3 | * trace binary printk | |
4 | * | |
5 | * Copyright (C) 2008 Lai Jiangshan <laijs@cn.fujitsu.com> | |
6 | * | |
7 | */ | |
7975a2be | 8 | #include <linux/seq_file.h> |
17911ff3 | 9 | #include <linux/security.h> |
7975a2be | 10 | #include <linux/uaccess.h> |
1427cdf0 LJ |
11 | #include <linux/kernel.h> |
12 | #include <linux/ftrace.h> | |
13 | #include <linux/string.h> | |
7975a2be | 14 | #include <linux/module.h> |
7975a2be | 15 | #include <linux/mutex.h> |
1427cdf0 LJ |
16 | #include <linux/ctype.h> |
17 | #include <linux/list.h> | |
1427cdf0 | 18 | #include <linux/slab.h> |
1427cdf0 LJ |
19 | |
20 | #include "trace.h" | |
21 | ||
1ba28e02 LJ |
22 | #ifdef CONFIG_MODULES |
23 | ||
1ba28e02 | 24 | /* |
769b0441 | 25 | * modules trace_printk()'s formats are autosaved in struct trace_bprintk_fmt |
1ba28e02 LJ |
26 | * which are queued on trace_bprintk_fmt_list. |
27 | */ | |
28 | static LIST_HEAD(trace_bprintk_fmt_list); | |
29 | ||
769b0441 FW |
30 | /* serialize accesses to trace_bprintk_fmt_list */ |
31 | static DEFINE_MUTEX(btrace_mutex); | |
32 | ||
1ba28e02 LJ |
33 | struct trace_bprintk_fmt { |
34 | struct list_head list; | |
0588fa30 | 35 | const char *fmt; |
1ba28e02 LJ |
36 | }; |
37 | ||
1ba28e02 | 38 | static inline struct trace_bprintk_fmt *lookup_format(const char *fmt) |
1427cdf0 | 39 | { |
1ba28e02 | 40 | struct trace_bprintk_fmt *pos; |
70c8217a SRRH |
41 | |
42 | if (!fmt) | |
43 | return ERR_PTR(-EINVAL); | |
44 | ||
1ba28e02 LJ |
45 | list_for_each_entry(pos, &trace_bprintk_fmt_list, list) { |
46 | if (!strcmp(pos->fmt, fmt)) | |
47 | return pos; | |
48 | } | |
49 | return NULL; | |
1427cdf0 LJ |
50 | } |
51 | ||
1ba28e02 LJ |
52 | static |
53 | void hold_module_trace_bprintk_format(const char **start, const char **end) | |
1427cdf0 | 54 | { |
1ba28e02 | 55 | const char **iter; |
0588fa30 | 56 | char *fmt; |
769b0441 | 57 | |
07d777fe SR |
58 | /* allocate the trace_printk per cpu buffers */ |
59 | if (start != end) | |
60 | trace_printk_init_buffers(); | |
61 | ||
769b0441 | 62 | mutex_lock(&btrace_mutex); |
1ba28e02 LJ |
63 | for (iter = start; iter < end; iter++) { |
64 | struct trace_bprintk_fmt *tb_fmt = lookup_format(*iter); | |
65 | if (tb_fmt) { | |
70c8217a SRRH |
66 | if (!IS_ERR(tb_fmt)) |
67 | *iter = tb_fmt->fmt; | |
1ba28e02 LJ |
68 | continue; |
69 | } | |
70 | ||
3a301d7c | 71 | fmt = NULL; |
0588fa30 | 72 | tb_fmt = kmalloc(sizeof(*tb_fmt), GFP_KERNEL); |
3a301d7c | 73 | if (tb_fmt) { |
0588fa30 | 74 | fmt = kmalloc(strlen(*iter) + 1, GFP_KERNEL); |
3a301d7c SR |
75 | if (fmt) { |
76 | list_add_tail(&tb_fmt->list, &trace_bprintk_fmt_list); | |
77 | strcpy(fmt, *iter); | |
78 | tb_fmt->fmt = fmt; | |
79 | } else | |
80 | kfree(tb_fmt); | |
0588fa30 | 81 | } |
3a301d7c SR |
82 | *iter = fmt; |
83 | ||
1ba28e02 | 84 | } |
769b0441 | 85 | mutex_unlock(&btrace_mutex); |
1427cdf0 LJ |
86 | } |
87 | ||
1ba28e02 LJ |
88 | static int module_trace_bprintk_format_notify(struct notifier_block *self, |
89 | unsigned long val, void *data) | |
90 | { | |
91 | struct module *mod = data; | |
92 | if (mod->num_trace_bprintk_fmt) { | |
93 | const char **start = mod->trace_bprintk_fmt_start; | |
94 | const char **end = start + mod->num_trace_bprintk_fmt; | |
95 | ||
96 | if (val == MODULE_STATE_COMING) | |
97 | hold_module_trace_bprintk_format(start, end); | |
98 | } | |
0340a6b7 | 99 | return NOTIFY_OK; |
1ba28e02 LJ |
100 | } |
101 | ||
1813dc37 SR |
102 | /* |
103 | * The debugfs/tracing/printk_formats file maps the addresses with | |
104 | * the ASCII formats that are used in the bprintk events in the | |
105 | * buffer. For userspace tools to be able to decode the events from | |
106 | * the buffer, they need to be able to map the address with the format. | |
107 | * | |
108 | * The addresses of the bprintk formats are in their own section | |
109 | * __trace_printk_fmt. But for modules we copy them into a link list. | |
110 | * The code to print the formats and their addresses passes around the | |
111 | * address of the fmt string. If the fmt address passed into the seq | |
112 | * functions is within the kernel core __trace_printk_fmt section, then | |
113 | * it simply uses the next pointer in the list. | |
114 | * | |
115 | * When the fmt pointer is outside the kernel core __trace_printk_fmt | |
116 | * section, then we need to read the link list pointers. The trick is | |
117 | * we pass the address of the string to the seq function just like | |
118 | * we do for the kernel core formats. To get back the structure that | |
ca9184f0 | 119 | * holds the format, we simply use container_of() and then go to the |
1813dc37 SR |
120 | * next format in the list. |
121 | */ | |
122 | static const char ** | |
123 | find_next_mod_format(int start_index, void *v, const char **fmt, loff_t *pos) | |
124 | { | |
125 | struct trace_bprintk_fmt *mod_fmt; | |
126 | ||
127 | if (list_empty(&trace_bprintk_fmt_list)) | |
128 | return NULL; | |
129 | ||
130 | /* | |
131 | * v will point to the address of the fmt record from t_next | |
132 | * v will be NULL from t_start. | |
133 | * If this is the first pointer or called from start | |
134 | * then we need to walk the list. | |
135 | */ | |
136 | if (!v || start_index == *pos) { | |
137 | struct trace_bprintk_fmt *p; | |
138 | ||
139 | /* search the module list */ | |
140 | list_for_each_entry(p, &trace_bprintk_fmt_list, list) { | |
141 | if (start_index == *pos) | |
142 | return &p->fmt; | |
143 | start_index++; | |
144 | } | |
145 | /* pos > index */ | |
146 | return NULL; | |
147 | } | |
148 | ||
149 | /* | |
150 | * v points to the address of the fmt field in the mod list | |
151 | * structure that holds the module print format. | |
152 | */ | |
153 | mod_fmt = container_of(v, typeof(*mod_fmt), fmt); | |
154 | if (mod_fmt->list.next == &trace_bprintk_fmt_list) | |
155 | return NULL; | |
156 | ||
157 | mod_fmt = container_of(mod_fmt->list.next, typeof(*mod_fmt), list); | |
158 | ||
159 | return &mod_fmt->fmt; | |
160 | } | |
161 | ||
162 | static void format_mod_start(void) | |
163 | { | |
164 | mutex_lock(&btrace_mutex); | |
165 | } | |
166 | ||
167 | static void format_mod_stop(void) | |
168 | { | |
169 | mutex_unlock(&btrace_mutex); | |
170 | } | |
171 | ||
1ba28e02 LJ |
172 | #else /* !CONFIG_MODULES */ |
173 | __init static int | |
174 | module_trace_bprintk_format_notify(struct notifier_block *self, | |
175 | unsigned long val, void *data) | |
176 | { | |
0340a6b7 | 177 | return NOTIFY_OK; |
1ba28e02 | 178 | } |
1813dc37 SR |
179 | static inline const char ** |
180 | find_next_mod_format(int start_index, void *v, const char **fmt, loff_t *pos) | |
181 | { | |
182 | return NULL; | |
183 | } | |
184 | static inline void format_mod_start(void) { } | |
185 | static inline void format_mod_stop(void) { } | |
1ba28e02 LJ |
186 | #endif /* CONFIG_MODULES */ |
187 | ||
b9f9108c SRRH |
188 | static bool __read_mostly trace_printk_enabled = true; |
189 | ||
190 | void trace_printk_control(bool enabled) | |
191 | { | |
192 | trace_printk_enabled = enabled; | |
193 | } | |
1ba28e02 LJ |
194 | |
195 | __initdata_or_module static | |
196 | struct notifier_block module_trace_bprintk_format_nb = { | |
197 | .notifier_call = module_trace_bprintk_format_notify, | |
198 | }; | |
199 | ||
48ead020 | 200 | int __trace_bprintk(unsigned long ip, const char *fmt, ...) |
447a5647 | 201 | { |
769b0441 FW |
202 | int ret; |
203 | va_list ap; | |
1427cdf0 | 204 | |
769b0441 FW |
205 | if (unlikely(!fmt)) |
206 | return 0; | |
1427cdf0 | 207 | |
b9f9108c | 208 | if (!trace_printk_enabled) |
769b0441 FW |
209 | return 0; |
210 | ||
211 | va_start(ap, fmt); | |
40ce74f1 | 212 | ret = trace_vbprintk(ip, fmt, ap); |
769b0441 FW |
213 | va_end(ap); |
214 | return ret; | |
1427cdf0 | 215 | } |
48ead020 | 216 | EXPORT_SYMBOL_GPL(__trace_bprintk); |
1427cdf0 | 217 | |
48ead020 | 218 | int __ftrace_vbprintk(unsigned long ip, const char *fmt, va_list ap) |
447a5647 | 219 | { |
769b0441 FW |
220 | if (unlikely(!fmt)) |
221 | return 0; | |
222 | ||
b9f9108c | 223 | if (!trace_printk_enabled) |
769b0441 FW |
224 | return 0; |
225 | ||
40ce74f1 | 226 | return trace_vbprintk(ip, fmt, ap); |
48ead020 FW |
227 | } |
228 | EXPORT_SYMBOL_GPL(__ftrace_vbprintk); | |
229 | ||
230 | int __trace_printk(unsigned long ip, const char *fmt, ...) | |
231 | { | |
232 | int ret; | |
233 | va_list ap; | |
234 | ||
b9f9108c | 235 | if (!trace_printk_enabled) |
48ead020 FW |
236 | return 0; |
237 | ||
238 | va_start(ap, fmt); | |
40ce74f1 | 239 | ret = trace_vprintk(ip, fmt, ap); |
48ead020 FW |
240 | va_end(ap); |
241 | return ret; | |
242 | } | |
243 | EXPORT_SYMBOL_GPL(__trace_printk); | |
244 | ||
245 | int __ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap) | |
246 | { | |
b9f9108c | 247 | if (!trace_printk_enabled) |
48ead020 FW |
248 | return 0; |
249 | ||
40ce74f1 | 250 | return trace_vprintk(ip, fmt, ap); |
1427cdf0 | 251 | } |
769b0441 | 252 | EXPORT_SYMBOL_GPL(__ftrace_vprintk); |
1427cdf0 | 253 | |
9a6944fe SRV |
254 | bool trace_is_tracepoint_string(const char *str) |
255 | { | |
256 | const char **ptr = __start___tracepoint_str; | |
257 | ||
258 | for (ptr = __start___tracepoint_str; ptr < __stop___tracepoint_str; ptr++) { | |
259 | if (str == *ptr) | |
260 | return true; | |
261 | } | |
262 | return false; | |
263 | } | |
264 | ||
1813dc37 SR |
265 | static const char **find_next(void *v, loff_t *pos) |
266 | { | |
267 | const char **fmt = v; | |
268 | int start_index; | |
102c9323 | 269 | int last_index; |
1813dc37 | 270 | |
1813dc37 SR |
271 | start_index = __stop___trace_bprintk_fmt - __start___trace_bprintk_fmt; |
272 | ||
273 | if (*pos < start_index) | |
db5e7ecc | 274 | return __start___trace_bprintk_fmt + *pos; |
1813dc37 | 275 | |
102c9323 SRRH |
276 | /* |
277 | * The __tracepoint_str section is treated the same as the | |
278 | * __trace_printk_fmt section. The difference is that the | |
279 | * __trace_printk_fmt section should only be used by trace_printk() | |
280 | * in a debugging environment, as if anything exists in that section | |
281 | * the trace_prink() helper buffers are allocated, which would just | |
282 | * waste space in a production environment. | |
283 | * | |
284 | * The __tracepoint_str sections on the other hand are used by | |
285 | * tracepoints which need to map pointers to their strings to | |
286 | * the ASCII text for userspace. | |
287 | */ | |
288 | last_index = start_index; | |
289 | start_index = __stop___tracepoint_str - __start___tracepoint_str; | |
290 | ||
291 | if (*pos < last_index + start_index) | |
292 | return __start___tracepoint_str + (*pos - last_index); | |
293 | ||
f36d1be2 | 294 | start_index += last_index; |
1813dc37 SR |
295 | return find_next_mod_format(start_index, v, fmt, pos); |
296 | } | |
297 | ||
7975a2be | 298 | static void * |
c8961ec6 | 299 | t_start(struct seq_file *m, loff_t *pos) |
7975a2be | 300 | { |
1813dc37 SR |
301 | format_mod_start(); |
302 | return find_next(NULL, pos); | |
7975a2be SR |
303 | } |
304 | ||
c8961ec6 | 305 | static void *t_next(struct seq_file *m, void * v, loff_t *pos) |
7975a2be | 306 | { |
c8961ec6 | 307 | (*pos)++; |
1813dc37 | 308 | return find_next(v, pos); |
7975a2be SR |
309 | } |
310 | ||
311 | static int t_show(struct seq_file *m, void *v) | |
312 | { | |
313 | const char **fmt = v; | |
314 | const char *str = *fmt; | |
315 | int i; | |
316 | ||
3debb0a9 SRRH |
317 | if (!*fmt) |
318 | return 0; | |
319 | ||
4c739ff0 | 320 | seq_printf(m, "0x%lx : \"", *(unsigned long *)fmt); |
7975a2be SR |
321 | |
322 | /* | |
323 | * Tabs and new lines need to be converted. | |
324 | */ | |
325 | for (i = 0; str[i]; i++) { | |
326 | switch (str[i]) { | |
327 | case '\n': | |
328 | seq_puts(m, "\\n"); | |
329 | break; | |
330 | case '\t': | |
331 | seq_puts(m, "\\t"); | |
332 | break; | |
333 | case '\\': | |
1177e436 | 334 | seq_putc(m, '\\'); |
7975a2be SR |
335 | break; |
336 | case '"': | |
337 | seq_puts(m, "\\\""); | |
338 | break; | |
339 | default: | |
340 | seq_putc(m, str[i]); | |
341 | } | |
342 | } | |
343 | seq_puts(m, "\"\n"); | |
344 | ||
345 | return 0; | |
346 | } | |
347 | ||
348 | static void t_stop(struct seq_file *m, void *p) | |
349 | { | |
1813dc37 | 350 | format_mod_stop(); |
7975a2be SR |
351 | } |
352 | ||
353 | static const struct seq_operations show_format_seq_ops = { | |
354 | .start = t_start, | |
355 | .next = t_next, | |
356 | .show = t_show, | |
357 | .stop = t_stop, | |
358 | }; | |
359 | ||
360 | static int | |
361 | ftrace_formats_open(struct inode *inode, struct file *file) | |
362 | { | |
17911ff3 SRV |
363 | int ret; |
364 | ||
365 | ret = security_locked_down(LOCKDOWN_TRACEFS); | |
366 | if (ret) | |
367 | return ret; | |
368 | ||
c8961ec6 | 369 | return seq_open(file, &show_format_seq_ops); |
7975a2be SR |
370 | } |
371 | ||
372 | static const struct file_operations ftrace_formats_fops = { | |
373 | .open = ftrace_formats_open, | |
374 | .read = seq_read, | |
375 | .llseek = seq_lseek, | |
376 | .release = seq_release, | |
377 | }; | |
378 | ||
379 | static __init int init_trace_printk_function_export(void) | |
380 | { | |
22c36b18 | 381 | int ret; |
7975a2be | 382 | |
22c36b18 WY |
383 | ret = tracing_init_dentry(); |
384 | if (ret) | |
7975a2be SR |
385 | return 0; |
386 | ||
bd324cfc | 387 | trace_create_file("printk_formats", TRACE_MODE_READ, NULL, |
7975a2be | 388 | NULL, &ftrace_formats_fops); |
7975a2be SR |
389 | |
390 | return 0; | |
391 | } | |
392 | ||
393 | fs_initcall(init_trace_printk_function_export); | |
394 | ||
769b0441 | 395 | static __init int init_trace_printk(void) |
1427cdf0 | 396 | { |
769b0441 | 397 | return register_module_notifier(&module_trace_bprintk_format_nb); |
1427cdf0 LJ |
398 | } |
399 | ||
769b0441 | 400 | early_initcall(init_trace_printk); |