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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/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);
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 mutex_lock(&btrace_mutex);
55 for (iter = start; iter < end; iter++) {
56 struct trace_bprintk_fmt *tb_fmt = lookup_format(*iter);
57 if (tb_fmt) {
58 *iter = tb_fmt->fmt;
59 continue;
60 }
61
62 tb_fmt = kmalloc(sizeof(*tb_fmt), GFP_KERNEL);
63 if (tb_fmt)
64 fmt = kmalloc(strlen(*iter) + 1, GFP_KERNEL);
65 if (tb_fmt && fmt) {
66 list_add_tail(&tb_fmt->list, &trace_bprintk_fmt_list);
67 strcpy(fmt, *iter);
68 tb_fmt->fmt = fmt;
69 *iter = tb_fmt->fmt;
70 } else {
71 kfree(tb_fmt);
72 *iter = NULL;
73 }
74 }
75 mutex_unlock(&btrace_mutex);
76}
77
78static int module_trace_bprintk_format_notify(struct notifier_block *self,
79 unsigned long val, void *data)
80{
81 struct module *mod = data;
82 if (mod->num_trace_bprintk_fmt) {
83 const char **start = mod->trace_bprintk_fmt_start;
84 const char **end = start + mod->num_trace_bprintk_fmt;
85
86 if (val == MODULE_STATE_COMING)
87 hold_module_trace_bprintk_format(start, end);
88 }
89 return 0;
90}
91
92/*
93 * The debugfs/tracing/printk_formats file maps the addresses with
94 * the ASCII formats that are used in the bprintk events in the
95 * buffer. For userspace tools to be able to decode the events from
96 * the buffer, they need to be able to map the address with the format.
97 *
98 * The addresses of the bprintk formats are in their own section
99 * __trace_printk_fmt. But for modules we copy them into a link list.
100 * The code to print the formats and their addresses passes around the
101 * address of the fmt string. If the fmt address passed into the seq
102 * functions is within the kernel core __trace_printk_fmt section, then
103 * it simply uses the next pointer in the list.
104 *
105 * When the fmt pointer is outside the kernel core __trace_printk_fmt
106 * section, then we need to read the link list pointers. The trick is
107 * we pass the address of the string to the seq function just like
108 * we do for the kernel core formats. To get back the structure that
109 * holds the format, we simply use containerof() and then go to the
110 * next format in the list.
111 */
112static const char **
113find_next_mod_format(int start_index, void *v, const char **fmt, loff_t *pos)
114{
115 struct trace_bprintk_fmt *mod_fmt;
116
117 if (list_empty(&trace_bprintk_fmt_list))
118 return NULL;
119
120 /*
121 * v will point to the address of the fmt record from t_next
122 * v will be NULL from t_start.
123 * If this is the first pointer or called from start
124 * then we need to walk the list.
125 */
126 if (!v || start_index == *pos) {
127 struct trace_bprintk_fmt *p;
128
129 /* search the module list */
130 list_for_each_entry(p, &trace_bprintk_fmt_list, list) {
131 if (start_index == *pos)
132 return &p->fmt;
133 start_index++;
134 }
135 /* pos > index */
136 return NULL;
137 }
138
139 /*
140 * v points to the address of the fmt field in the mod list
141 * structure that holds the module print format.
142 */
143 mod_fmt = container_of(v, typeof(*mod_fmt), fmt);
144 if (mod_fmt->list.next == &trace_bprintk_fmt_list)
145 return NULL;
146
147 mod_fmt = container_of(mod_fmt->list.next, typeof(*mod_fmt), list);
148
149 return &mod_fmt->fmt;
150}
151
152static void format_mod_start(void)
153{
154 mutex_lock(&btrace_mutex);
155}
156
157static void format_mod_stop(void)
158{
159 mutex_unlock(&btrace_mutex);
160}
161
162#else /* !CONFIG_MODULES */
163__init static int
164module_trace_bprintk_format_notify(struct notifier_block *self,
165 unsigned long val, void *data)
166{
167 return 0;
168}
169static inline const char **
170find_next_mod_format(int start_index, void *v, const char **fmt, loff_t *pos)
171{
172 return NULL;
173}
174static inline void format_mod_start(void) { }
175static inline void format_mod_stop(void) { }
176#endif /* CONFIG_MODULES */
177
178
179__initdata_or_module static
180struct notifier_block module_trace_bprintk_format_nb = {
181 .notifier_call = module_trace_bprintk_format_notify,
182};
183
184int __trace_bprintk(unsigned long ip, const char *fmt, ...)
185 {
186 int ret;
187 va_list ap;
188
189 if (unlikely(!fmt))
190 return 0;
191
192 if (!(trace_flags & TRACE_ITER_PRINTK))
193 return 0;
194
195 va_start(ap, fmt);
196 ret = trace_vbprintk(ip, fmt, ap);
197 va_end(ap);
198 return ret;
199}
200EXPORT_SYMBOL_GPL(__trace_bprintk);
201
202int __ftrace_vbprintk(unsigned long ip, const char *fmt, va_list ap)
203 {
204 if (unlikely(!fmt))
205 return 0;
206
207 if (!(trace_flags & TRACE_ITER_PRINTK))
208 return 0;
209
210 return trace_vbprintk(ip, fmt, ap);
211}
212EXPORT_SYMBOL_GPL(__ftrace_vbprintk);
213
214int __trace_printk(unsigned long ip, const char *fmt, ...)
215{
216 int ret;
217 va_list ap;
218
219 if (!(trace_flags & TRACE_ITER_PRINTK))
220 return 0;
221
222 va_start(ap, fmt);
223 ret = trace_vprintk(ip, fmt, ap);
224 va_end(ap);
225 return ret;
226}
227EXPORT_SYMBOL_GPL(__trace_printk);
228
229int __ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap)
230{
231 if (!(trace_flags & TRACE_ITER_PRINTK))
232 return 0;
233
234 return trace_vprintk(ip, fmt, ap);
235}
236EXPORT_SYMBOL_GPL(__ftrace_vprintk);
237
238static const char **find_next(void *v, loff_t *pos)
239{
240 const char **fmt = v;
241 int start_index;
242
243 start_index = __stop___trace_bprintk_fmt - __start___trace_bprintk_fmt;
244
245 if (*pos < start_index)
246 return __start___trace_bprintk_fmt + *pos;
247
248 return find_next_mod_format(start_index, v, fmt, pos);
249}
250
251static void *
252t_start(struct seq_file *m, loff_t *pos)
253{
254 format_mod_start();
255 return find_next(NULL, pos);
256}
257
258static void *t_next(struct seq_file *m, void * v, loff_t *pos)
259{
260 (*pos)++;
261 return find_next(v, pos);
262}
263
264static int t_show(struct seq_file *m, void *v)
265{
266 const char **fmt = v;
267 const char *str = *fmt;
268 int i;
269
270 seq_printf(m, "0x%lx : \"", *(unsigned long *)fmt);
271
272 /*
273 * Tabs and new lines need to be converted.
274 */
275 for (i = 0; str[i]; i++) {
276 switch (str[i]) {
277 case '\n':
278 seq_puts(m, "\\n");
279 break;
280 case '\t':
281 seq_puts(m, "\\t");
282 break;
283 case '\\':
284 seq_puts(m, "\\");
285 break;
286 case '"':
287 seq_puts(m, "\\\"");
288 break;
289 default:
290 seq_putc(m, str[i]);
291 }
292 }
293 seq_puts(m, "\"\n");
294
295 return 0;
296}
297
298static void t_stop(struct seq_file *m, void *p)
299{
300 format_mod_stop();
301}
302
303static const struct seq_operations show_format_seq_ops = {
304 .start = t_start,
305 .next = t_next,
306 .show = t_show,
307 .stop = t_stop,
308};
309
310static int
311ftrace_formats_open(struct inode *inode, struct file *file)
312{
313 return seq_open(file, &show_format_seq_ops);
314}
315
316static const struct file_operations ftrace_formats_fops = {
317 .open = ftrace_formats_open,
318 .read = seq_read,
319 .llseek = seq_lseek,
320 .release = seq_release,
321};
322
323static __init int init_trace_printk_function_export(void)
324{
325 struct dentry *d_tracer;
326
327 d_tracer = tracing_init_dentry();
328 if (!d_tracer)
329 return 0;
330
331 trace_create_file("printk_formats", 0444, d_tracer,
332 NULL, &ftrace_formats_fops);
333
334 return 0;
335}
336
337fs_initcall(init_trace_printk_function_export);
338
339static __init int init_trace_printk(void)
340{
341 return register_module_notifier(&module_trace_bprintk_format_nb);
342}
343
344early_initcall(init_trace_printk);