Home Home > GIT Browse
summaryrefslogtreecommitdiff
blob: 6b1c562ffdaf0f0be1549e5eb34b8a199c11b273 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
// SPDX-License-Identifier: GPL-2.0
/*
 * trace_seq.c
 *
 * Copyright (C) 2008-2014 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
 *
 * The trace_seq is a handy tool that allows you to pass a descriptor around
 * to a buffer that other functions can write to. It is similar to the
 * seq_file functionality but has some differences.
 *
 * To use it, the trace_seq must be initialized with trace_seq_init().
 * This will set up the counters within the descriptor. You can call
 * trace_seq_init() more than once to reset the trace_seq to start
 * from scratch.
 * 
 * The buffer size is currently PAGE_SIZE, although it may become dynamic
 * in the future.
 *
 * A write to the buffer will either succed or fail. That is, unlike
 * sprintf() there will not be a partial write (well it may write into
 * the buffer but it wont update the pointers). This allows users to
 * try to write something into the trace_seq buffer and if it fails
 * they can flush it and try again.
 *
 */
#include <linux/uaccess.h>
#include <linux/seq_file.h>
#include <linux/trace_seq.h>

/* How much buffer is left on the trace_seq? */
#define TRACE_SEQ_BUF_LEFT(s) seq_buf_buffer_left(&(s)->seq)

/* How much buffer is written? */
#define TRACE_SEQ_BUF_USED(s) seq_buf_used(&(s)->seq)

/*
 * trace_seq should work with being initialized with 0s.
 */
static inline void __trace_seq_init(struct trace_seq *s)
{
	if (unlikely(!s->seq.size))
		trace_seq_init(s);
}

/**
 * trace_print_seq - move the contents of trace_seq into a seq_file
 * @m: the seq_file descriptor that is the destination
 * @s: the trace_seq descriptor that is the source.
 *
 * Returns 0 on success and non zero on error. If it succeeds to
 * write to the seq_file it will reset the trace_seq, otherwise
 * it does not modify the trace_seq to let the caller try again.
 */
int trace_print_seq(struct seq_file *m, struct trace_seq *s)
{
	int ret;

	__trace_seq_init(s);

	ret = seq_buf_print_seq(m, &s->seq);

	/*
	 * Only reset this buffer if we successfully wrote to the
	 * seq_file buffer. This lets the caller try again or
	 * do something else with the contents.
	 */
	if (!ret)
		trace_seq_init(s);

	return ret;
}

/**
 * trace_seq_printf - sequence printing of trace information
 * @s: trace sequence descriptor
 * @fmt: printf format string
 *
 * The tracer may use either sequence operations or its own
 * copy to user routines. To simplify formating of a trace
 * trace_seq_printf() is used to store strings into a special
 * buffer (@s). Then the output may be either used by
 * the sequencer or pulled into another buffer.
 */
void trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
{
	unsigned int save_len = s->seq.len;
	va_list ap;

	if (s->full)
		return;

	__trace_seq_init(s);

	va_start(ap, fmt);
	seq_buf_vprintf(&s->seq, fmt, ap);
	va_end(ap);

	/* If we can't write it all, don't bother writing anything */
	if (unlikely(seq_buf_has_overflowed(&s->seq))) {
		s->seq.len = save_len;
		s->full = 1;
	}
}
EXPORT_SYMBOL_GPL(trace_seq_printf);

/**
 * trace_seq_bitmask - write a bitmask array in its ASCII representation
 * @s:		trace sequence descriptor
 * @maskp:	points to an array of unsigned longs that represent a bitmask
 * @nmaskbits:	The number of bits that are valid in @maskp
 *
 * Writes a ASCII representation of a bitmask string into @s.
 */
void trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
		      int nmaskbits)
{
	unsigned int save_len = s->seq.len;

	if (s->full)
		return;

	__trace_seq_init(s);

	seq_buf_printf(&s->seq, "%*pb", nmaskbits, maskp);

	if (unlikely(seq_buf_has_overflowed(&s->seq))) {
		s->seq.len = save_len;
		s->full = 1;
	}
}
EXPORT_SYMBOL_GPL(trace_seq_bitmask);

/**
 * trace_seq_vprintf - sequence printing of trace information
 * @s: trace sequence descriptor
 * @fmt: printf format string
 *
 * The tracer may use either sequence operations or its own
 * copy to user routines. To simplify formating of a trace
 * trace_seq_printf is used to store strings into a special
 * buffer (@s). Then the output may be either used by
 * the sequencer or pulled into another buffer.
 */
void trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args)
{
	unsigned int save_len = s->seq.len;

	if (s->full)
		return;

	__trace_seq_init(s);

	seq_buf_vprintf(&s->seq, fmt, args);

	/* If we can't write it all, don't bother writing anything */
	if (unlikely(seq_buf_has_overflowed(&s->seq))) {
		s->seq.len = save_len;
		s->full = 1;
	}
}
EXPORT_SYMBOL_GPL(trace_seq_vprintf);

/**
 * trace_seq_bprintf - Write the printf string from binary arguments
 * @s: trace sequence descriptor
 * @fmt: The format string for the @binary arguments
 * @binary: The binary arguments for @fmt.
 *
 * When recording in a fast path, a printf may be recorded with just
 * saving the format and the arguments as they were passed to the
 * function, instead of wasting cycles converting the arguments into
 * ASCII characters. Instead, the arguments are saved in a 32 bit
 * word array that is defined by the format string constraints.
 *
 * This function will take the format and the binary array and finish
 * the conversion into the ASCII string within the buffer.
 */
void trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary)
{
	unsigned int save_len = s->seq.len;

	if (s->full)
		return;

	__trace_seq_init(s);

	seq_buf_bprintf(&s->seq, fmt, binary);

	/* If we can't write it all, don't bother writing anything */
	if (unlikely(seq_buf_has_overflowed(&s->seq))) {
		s->seq.len = save_len;
		s->full = 1;
		return;
	}
}
EXPORT_SYMBOL_GPL(trace_seq_bprintf);

/**
 * trace_seq_puts - trace sequence printing of simple string
 * @s: trace sequence descriptor
 * @str: simple string to record
 *
 * The tracer may use either the sequence operations or its own
 * copy to user routines. This function records a simple string
 * into a special buffer (@s) for later retrieval by a sequencer
 * or other mechanism.
 */
void trace_seq_puts(struct trace_seq *s, const char *str)
{
	unsigned int len = strlen(str);

	if (s->full)
		return;

	__trace_seq_init(s);

	if (len > TRACE_SEQ_BUF_LEFT(s)) {
		s->full = 1;
		return;
	}

	seq_buf_putmem(&s->seq, str, len);
}
EXPORT_SYMBOL_GPL(trace_seq_puts);

/**
 * trace_seq_putc - trace sequence printing of simple character
 * @s: trace sequence descriptor
 * @c: simple character to record
 *
 * The tracer may use either the sequence operations or its own
 * copy to user routines. This function records a simple charater
 * into a special buffer (@s) for later retrieval by a sequencer
 * or other mechanism.
 */
void trace_seq_putc(struct trace_seq *s, unsigned char c)
{
	if (s->full)
		return;

	__trace_seq_init(s);

	if (TRACE_SEQ_BUF_LEFT(s) < 1) {
		s->full = 1;
		return;
	}

	seq_buf_putc(&s->seq, c);
}
EXPORT_SYMBOL_GPL(trace_seq_putc);

/**
 * trace_seq_putmem - write raw data into the trace_seq buffer
 * @s: trace sequence descriptor
 * @mem: The raw memory to copy into the buffer
 * @len: The length of the raw memory to copy (in bytes)
 *
 * There may be cases where raw memory needs to be written into the
 * buffer and a strcpy() would not work. Using this function allows
 * for such cases.
 */
void trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len)
{
	if (s->full)
		return;

	__trace_seq_init(s);

	if (len > TRACE_SEQ_BUF_LEFT(s)) {
		s->full = 1;
		return;
	}

	seq_buf_putmem(&s->seq, mem, len);
}
EXPORT_SYMBOL_GPL(trace_seq_putmem);

/**
 * trace_seq_putmem_hex - write raw memory into the buffer in ASCII hex
 * @s: trace sequence descriptor
 * @mem: The raw memory to write its hex ASCII representation of
 * @len: The length of the raw memory to copy (in bytes)
 *
 * This is similar to trace_seq_putmem() except instead of just copying the
 * raw memory into the buffer it writes its ASCII representation of it
 * in hex characters.
 */
void trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
			 unsigned int len)
{
	unsigned int save_len = s->seq.len;

	if (s->full)
		return;

	__trace_seq_init(s);

	/* Each byte is represented by two chars */
	if (len * 2 > TRACE_SEQ_BUF_LEFT(s)) {
		s->full = 1;
		return;
	}

	/* The added spaces can still cause an overflow */
	seq_buf_putmem_hex(&s->seq, mem, len);

	if (unlikely(seq_buf_has_overflowed(&s->seq))) {
		s->seq.len = save_len;
		s->full = 1;
		return;
	}
}
EXPORT_SYMBOL_GPL(trace_seq_putmem_hex);

/**
 * trace_seq_path - copy a path into the sequence buffer
 * @s: trace sequence descriptor
 * @path: path to write into the sequence buffer.
 *
 * Write a path name into the sequence buffer.
 *
 * Returns 1 if we successfully written all the contents to
 *   the buffer.
 * Returns 0 if we the length to write is bigger than the
 *   reserved buffer space. In this case, nothing gets written.
 */
int trace_seq_path(struct trace_seq *s, const struct path *path)
{
	unsigned int save_len = s->seq.len;

	if (s->full)
		return 0;

	__trace_seq_init(s);

	if (TRACE_SEQ_BUF_LEFT(s) < 1) {
		s->full = 1;
		return 0;
	}

	seq_buf_path(&s->seq, path, "\n");

	if (unlikely(seq_buf_has_overflowed(&s->seq))) {
		s->seq.len = save_len;
		s->full = 1;
		return 0;
	}

	return 1;
}
EXPORT_SYMBOL_GPL(trace_seq_path);

/**
 * trace_seq_to_user - copy the squence buffer to user space
 * @s: trace sequence descriptor
 * @ubuf: The userspace memory location to copy to
 * @cnt: The amount to copy
 *
 * Copies the sequence buffer into the userspace memory pointed to
 * by @ubuf. It starts from the last read position (@s->readpos)
 * and writes up to @cnt characters or till it reaches the end of
 * the content in the buffer (@s->len), which ever comes first.
 *
 * On success, it returns a positive number of the number of bytes
 * it copied.
 *
 * On failure it returns -EBUSY if all of the content in the
 * sequence has been already read, which includes nothing in the
 * sequenc (@s->len == @s->readpos).
 *
 * Returns -EFAULT if the copy to userspace fails.
 */
int trace_seq_to_user(struct trace_seq *s, char __user *ubuf, int cnt)
{
	__trace_seq_init(s);
	return seq_buf_to_user(&s->seq, ubuf, cnt);
}
EXPORT_SYMBOL_GPL(trace_seq_to_user);