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