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Commit | Line | Data |
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1427cdf0 LJ |
1 | /* |
2 | * trace binary printk | |
3 | * | |
4 | * Copyright (C) 2008 Lai Jiangshan <laijs@cn.fujitsu.com> | |
5 | * | |
6 | */ | |
7975a2be | 7 | #include <linux/seq_file.h> |
7975a2be | 8 | #include <linux/uaccess.h> |
1427cdf0 LJ |
9 | #include <linux/kernel.h> |
10 | #include <linux/ftrace.h> | |
11 | #include <linux/string.h> | |
7975a2be | 12 | #include <linux/module.h> |
7975a2be | 13 | #include <linux/mutex.h> |
1427cdf0 LJ |
14 | #include <linux/ctype.h> |
15 | #include <linux/list.h> | |
1427cdf0 | 16 | #include <linux/slab.h> |
1427cdf0 LJ |
17 | |
18 | #include "trace.h" | |
19 | ||
1ba28e02 LJ |
20 | #ifdef CONFIG_MODULES |
21 | ||
1ba28e02 | 22 | /* |
769b0441 | 23 | * modules trace_printk()'s formats are autosaved in struct trace_bprintk_fmt |
1ba28e02 LJ |
24 | * which are queued on trace_bprintk_fmt_list. |
25 | */ | |
26 | static LIST_HEAD(trace_bprintk_fmt_list); | |
27 | ||
769b0441 FW |
28 | /* serialize accesses to trace_bprintk_fmt_list */ |
29 | static DEFINE_MUTEX(btrace_mutex); | |
30 | ||
1ba28e02 LJ |
31 | struct trace_bprintk_fmt { |
32 | struct list_head list; | |
0588fa30 | 33 | const char *fmt; |
1ba28e02 LJ |
34 | }; |
35 | ||
1ba28e02 | 36 | static inline struct trace_bprintk_fmt *lookup_format(const char *fmt) |
1427cdf0 | 37 | { |
1ba28e02 | 38 | struct trace_bprintk_fmt *pos; |
70c8217a SRRH |
39 | |
40 | if (!fmt) | |
41 | return ERR_PTR(-EINVAL); | |
42 | ||
1ba28e02 LJ |
43 | list_for_each_entry(pos, &trace_bprintk_fmt_list, list) { |
44 | if (!strcmp(pos->fmt, fmt)) | |
45 | return pos; | |
46 | } | |
47 | return NULL; | |
1427cdf0 LJ |
48 | } |
49 | ||
1ba28e02 LJ |
50 | static |
51 | void hold_module_trace_bprintk_format(const char **start, const char **end) | |
1427cdf0 | 52 | { |
1ba28e02 | 53 | const char **iter; |
0588fa30 | 54 | char *fmt; |
769b0441 | 55 | |
07d777fe SR |
56 | /* allocate the trace_printk per cpu buffers */ |
57 | if (start != end) | |
58 | trace_printk_init_buffers(); | |
59 | ||
769b0441 | 60 | mutex_lock(&btrace_mutex); |
1ba28e02 LJ |
61 | for (iter = start; iter < end; iter++) { |
62 | struct trace_bprintk_fmt *tb_fmt = lookup_format(*iter); | |
63 | if (tb_fmt) { | |
70c8217a SRRH |
64 | if (!IS_ERR(tb_fmt)) |
65 | *iter = tb_fmt->fmt; | |
1ba28e02 LJ |
66 | continue; |
67 | } | |
68 | ||
3a301d7c | 69 | fmt = NULL; |
0588fa30 | 70 | tb_fmt = kmalloc(sizeof(*tb_fmt), GFP_KERNEL); |
3a301d7c | 71 | if (tb_fmt) { |
0588fa30 | 72 | fmt = kmalloc(strlen(*iter) + 1, GFP_KERNEL); |
3a301d7c SR |
73 | if (fmt) { |
74 | list_add_tail(&tb_fmt->list, &trace_bprintk_fmt_list); | |
75 | strcpy(fmt, *iter); | |
76 | tb_fmt->fmt = fmt; | |
77 | } else | |
78 | kfree(tb_fmt); | |
0588fa30 | 79 | } |
3a301d7c SR |
80 | *iter = fmt; |
81 | ||
1ba28e02 | 82 | } |
769b0441 | 83 | mutex_unlock(&btrace_mutex); |
1427cdf0 LJ |
84 | } |
85 | ||
1ba28e02 LJ |
86 | static int module_trace_bprintk_format_notify(struct notifier_block *self, |
87 | unsigned long val, void *data) | |
88 | { | |
89 | struct module *mod = data; | |
90 | if (mod->num_trace_bprintk_fmt) { | |
91 | const char **start = mod->trace_bprintk_fmt_start; | |
92 | const char **end = start + mod->num_trace_bprintk_fmt; | |
93 | ||
94 | if (val == MODULE_STATE_COMING) | |
95 | hold_module_trace_bprintk_format(start, end); | |
96 | } | |
97 | return 0; | |
98 | } | |
99 | ||
1813dc37 SR |
100 | /* |
101 | * The debugfs/tracing/printk_formats file maps the addresses with | |
102 | * the ASCII formats that are used in the bprintk events in the | |
103 | * buffer. For userspace tools to be able to decode the events from | |
104 | * the buffer, they need to be able to map the address with the format. | |
105 | * | |
106 | * The addresses of the bprintk formats are in their own section | |
107 | * __trace_printk_fmt. But for modules we copy them into a link list. | |
108 | * The code to print the formats and their addresses passes around the | |
109 | * address of the fmt string. If the fmt address passed into the seq | |
110 | * functions is within the kernel core __trace_printk_fmt section, then | |
111 | * it simply uses the next pointer in the list. | |
112 | * | |
113 | * When the fmt pointer is outside the kernel core __trace_printk_fmt | |
114 | * section, then we need to read the link list pointers. The trick is | |
115 | * we pass the address of the string to the seq function just like | |
116 | * we do for the kernel core formats. To get back the structure that | |
117 | * holds the format, we simply use containerof() and then go to the | |
118 | * next format in the list. | |
119 | */ | |
120 | static const char ** | |
121 | find_next_mod_format(int start_index, void *v, const char **fmt, loff_t *pos) | |
122 | { | |
123 | struct trace_bprintk_fmt *mod_fmt; | |
124 | ||
125 | if (list_empty(&trace_bprintk_fmt_list)) | |
126 | return NULL; | |
127 | ||
128 | /* | |
129 | * v will point to the address of the fmt record from t_next | |
130 | * v will be NULL from t_start. | |
131 | * If this is the first pointer or called from start | |
132 | * then we need to walk the list. | |
133 | */ | |
134 | if (!v || start_index == *pos) { | |
135 | struct trace_bprintk_fmt *p; | |
136 | ||
137 | /* search the module list */ | |
138 | list_for_each_entry(p, &trace_bprintk_fmt_list, list) { | |
139 | if (start_index == *pos) | |
140 | return &p->fmt; | |
141 | start_index++; | |
142 | } | |
143 | /* pos > index */ | |
144 | return NULL; | |
145 | } | |
146 | ||
147 | /* | |
148 | * v points to the address of the fmt field in the mod list | |
149 | * structure that holds the module print format. | |
150 | */ | |
151 | mod_fmt = container_of(v, typeof(*mod_fmt), fmt); | |
152 | if (mod_fmt->list.next == &trace_bprintk_fmt_list) | |
153 | return NULL; | |
154 | ||
155 | mod_fmt = container_of(mod_fmt->list.next, typeof(*mod_fmt), list); | |
156 | ||
157 | return &mod_fmt->fmt; | |
158 | } | |
159 | ||
160 | static void format_mod_start(void) | |
161 | { | |
162 | mutex_lock(&btrace_mutex); | |
163 | } | |
164 | ||
165 | static void format_mod_stop(void) | |
166 | { | |
167 | mutex_unlock(&btrace_mutex); | |
168 | } | |
169 | ||
1ba28e02 LJ |
170 | #else /* !CONFIG_MODULES */ |
171 | __init static int | |
172 | module_trace_bprintk_format_notify(struct notifier_block *self, | |
173 | unsigned long val, void *data) | |
174 | { | |
175 | return 0; | |
176 | } | |
1813dc37 SR |
177 | static inline const char ** |
178 | find_next_mod_format(int start_index, void *v, const char **fmt, loff_t *pos) | |
179 | { | |
180 | return NULL; | |
181 | } | |
182 | static inline void format_mod_start(void) { } | |
183 | static inline void format_mod_stop(void) { } | |
1ba28e02 LJ |
184 | #endif /* CONFIG_MODULES */ |
185 | ||
b9f9108c SRRH |
186 | static bool __read_mostly trace_printk_enabled = true; |
187 | ||
188 | void trace_printk_control(bool enabled) | |
189 | { | |
190 | trace_printk_enabled = enabled; | |
191 | } | |
1ba28e02 LJ |
192 | |
193 | __initdata_or_module static | |
194 | struct notifier_block module_trace_bprintk_format_nb = { | |
195 | .notifier_call = module_trace_bprintk_format_notify, | |
196 | }; | |
197 | ||
48ead020 | 198 | int __trace_bprintk(unsigned long ip, const char *fmt, ...) |
769b0441 FW |
199 | { |
200 | int ret; | |
201 | va_list ap; | |
1427cdf0 | 202 | |
769b0441 FW |
203 | if (unlikely(!fmt)) |
204 | return 0; | |
1427cdf0 | 205 | |
b9f9108c | 206 | if (!trace_printk_enabled) |
769b0441 FW |
207 | return 0; |
208 | ||
209 | va_start(ap, fmt); | |
40ce74f1 | 210 | ret = trace_vbprintk(ip, fmt, ap); |
769b0441 FW |
211 | va_end(ap); |
212 | return ret; | |
1427cdf0 | 213 | } |
48ead020 | 214 | EXPORT_SYMBOL_GPL(__trace_bprintk); |
1427cdf0 | 215 | |
48ead020 | 216 | int __ftrace_vbprintk(unsigned long ip, const char *fmt, va_list ap) |
769b0441 FW |
217 | { |
218 | if (unlikely(!fmt)) | |
219 | return 0; | |
220 | ||
b9f9108c | 221 | if (!trace_printk_enabled) |
769b0441 FW |
222 | return 0; |
223 | ||
40ce74f1 | 224 | return trace_vbprintk(ip, fmt, ap); |
48ead020 FW |
225 | } |
226 | EXPORT_SYMBOL_GPL(__ftrace_vbprintk); | |
227 | ||
228 | int __trace_printk(unsigned long ip, const char *fmt, ...) | |
229 | { | |
230 | int ret; | |
231 | va_list ap; | |
232 | ||
b9f9108c | 233 | if (!trace_printk_enabled) |
48ead020 FW |
234 | return 0; |
235 | ||
236 | va_start(ap, fmt); | |
40ce74f1 | 237 | ret = trace_vprintk(ip, fmt, ap); |
48ead020 FW |
238 | va_end(ap); |
239 | return ret; | |
240 | } | |
241 | EXPORT_SYMBOL_GPL(__trace_printk); | |
242 | ||
243 | int __ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap) | |
244 | { | |
b9f9108c | 245 | if (!trace_printk_enabled) |
48ead020 FW |
246 | return 0; |
247 | ||
40ce74f1 | 248 | return trace_vprintk(ip, fmt, ap); |
1427cdf0 | 249 | } |
769b0441 | 250 | EXPORT_SYMBOL_GPL(__ftrace_vprintk); |
1427cdf0 | 251 | |
1813dc37 SR |
252 | static const char **find_next(void *v, loff_t *pos) |
253 | { | |
254 | const char **fmt = v; | |
255 | int start_index; | |
102c9323 | 256 | int last_index; |
1813dc37 | 257 | |
1813dc37 SR |
258 | start_index = __stop___trace_bprintk_fmt - __start___trace_bprintk_fmt; |
259 | ||
260 | if (*pos < start_index) | |
db5e7ecc | 261 | return __start___trace_bprintk_fmt + *pos; |
1813dc37 | 262 | |
102c9323 SRRH |
263 | /* |
264 | * The __tracepoint_str section is treated the same as the | |
265 | * __trace_printk_fmt section. The difference is that the | |
266 | * __trace_printk_fmt section should only be used by trace_printk() | |
267 | * in a debugging environment, as if anything exists in that section | |
268 | * the trace_prink() helper buffers are allocated, which would just | |
269 | * waste space in a production environment. | |
270 | * | |
271 | * The __tracepoint_str sections on the other hand are used by | |
272 | * tracepoints which need to map pointers to their strings to | |
273 | * the ASCII text for userspace. | |
274 | */ | |
275 | last_index = start_index; | |
276 | start_index = __stop___tracepoint_str - __start___tracepoint_str; | |
277 | ||
278 | if (*pos < last_index + start_index) | |
279 | return __start___tracepoint_str + (*pos - last_index); | |
280 | ||
f36d1be2 | 281 | start_index += last_index; |
1813dc37 SR |
282 | return find_next_mod_format(start_index, v, fmt, pos); |
283 | } | |
284 | ||
7975a2be | 285 | static void * |
c8961ec6 | 286 | t_start(struct seq_file *m, loff_t *pos) |
7975a2be | 287 | { |
1813dc37 SR |
288 | format_mod_start(); |
289 | return find_next(NULL, pos); | |
7975a2be SR |
290 | } |
291 | ||
c8961ec6 | 292 | static void *t_next(struct seq_file *m, void * v, loff_t *pos) |
7975a2be | 293 | { |
c8961ec6 | 294 | (*pos)++; |
1813dc37 | 295 | return find_next(v, pos); |
7975a2be SR |
296 | } |
297 | ||
298 | static int t_show(struct seq_file *m, void *v) | |
299 | { | |
300 | const char **fmt = v; | |
301 | const char *str = *fmt; | |
302 | int i; | |
303 | ||
3debb0a9 SRRH |
304 | if (!*fmt) |
305 | return 0; | |
306 | ||
4c739ff0 | 307 | seq_printf(m, "0x%lx : \"", *(unsigned long *)fmt); |
7975a2be SR |
308 | |
309 | /* | |
310 | * Tabs and new lines need to be converted. | |
311 | */ | |
312 | for (i = 0; str[i]; i++) { | |
313 | switch (str[i]) { | |
314 | case '\n': | |
315 | seq_puts(m, "\\n"); | |
316 | break; | |
317 | case '\t': | |
318 | seq_puts(m, "\\t"); | |
319 | break; | |
320 | case '\\': | |
1177e436 | 321 | seq_putc(m, '\\'); |
7975a2be SR |
322 | break; |
323 | case '"': | |
324 | seq_puts(m, "\\\""); | |
325 | break; | |
326 | default: | |
327 | seq_putc(m, str[i]); | |
328 | } | |
329 | } | |
330 | seq_puts(m, "\"\n"); | |
331 | ||
332 | return 0; | |
333 | } | |
334 | ||
335 | static void t_stop(struct seq_file *m, void *p) | |
336 | { | |
1813dc37 | 337 | format_mod_stop(); |
7975a2be SR |
338 | } |
339 | ||
340 | static const struct seq_operations show_format_seq_ops = { | |
341 | .start = t_start, | |
342 | .next = t_next, | |
343 | .show = t_show, | |
344 | .stop = t_stop, | |
345 | }; | |
346 | ||
347 | static int | |
348 | ftrace_formats_open(struct inode *inode, struct file *file) | |
349 | { | |
c8961ec6 | 350 | return seq_open(file, &show_format_seq_ops); |
7975a2be SR |
351 | } |
352 | ||
353 | static const struct file_operations ftrace_formats_fops = { | |
354 | .open = ftrace_formats_open, | |
355 | .read = seq_read, | |
356 | .llseek = seq_lseek, | |
357 | .release = seq_release, | |
358 | }; | |
359 | ||
360 | static __init int init_trace_printk_function_export(void) | |
361 | { | |
362 | struct dentry *d_tracer; | |
7975a2be SR |
363 | |
364 | d_tracer = tracing_init_dentry(); | |
14a5ae40 | 365 | if (IS_ERR(d_tracer)) |
7975a2be SR |
366 | return 0; |
367 | ||
5452af66 | 368 | trace_create_file("printk_formats", 0444, d_tracer, |
7975a2be | 369 | NULL, &ftrace_formats_fops); |
7975a2be SR |
370 | |
371 | return 0; | |
372 | } | |
373 | ||
374 | fs_initcall(init_trace_printk_function_export); | |
375 | ||
769b0441 | 376 | static __init int init_trace_printk(void) |
1427cdf0 | 377 | { |
769b0441 | 378 | return register_module_notifier(&module_trace_bprintk_format_nb); |
1427cdf0 LJ |
379 | } |
380 | ||
769b0441 | 381 | early_initcall(init_trace_printk); |