Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0
2 : /*
3 : * trace_seq.c
4 : *
5 : * Copyright (C) 2008-2014 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
6 : *
7 : * The trace_seq is a handy tool that allows you to pass a descriptor around
8 : * to a buffer that other functions can write to. It is similar to the
9 : * seq_file functionality but has some differences.
10 : *
11 : * To use it, the trace_seq must be initialized with trace_seq_init().
12 : * This will set up the counters within the descriptor. You can call
13 : * trace_seq_init() more than once to reset the trace_seq to start
14 : * from scratch.
15 : *
16 : * The buffer size is currently PAGE_SIZE, although it may become dynamic
17 : * in the future.
18 : *
19 : * A write to the buffer will either succed or fail. That is, unlike
20 : * sprintf() there will not be a partial write (well it may write into
21 : * the buffer but it wont update the pointers). This allows users to
22 : * try to write something into the trace_seq buffer and if it fails
23 : * they can flush it and try again.
24 : *
25 : */
26 : #include <linux/uaccess.h>
27 : #include <linux/seq_file.h>
28 : #include <linux/trace_seq.h>
29 :
30 : /* How much buffer is left on the trace_seq? */
31 : #define TRACE_SEQ_BUF_LEFT(s) seq_buf_buffer_left(&(s)->seq)
32 :
33 : /*
34 : * trace_seq should work with being initialized with 0s.
35 : */
36 0 : static inline void __trace_seq_init(struct trace_seq *s)
37 : {
38 0 : if (unlikely(!s->seq.size))
39 0 : trace_seq_init(s);
40 : }
41 :
42 : /**
43 : * trace_print_seq - move the contents of trace_seq into a seq_file
44 : * @m: the seq_file descriptor that is the destination
45 : * @s: the trace_seq descriptor that is the source.
46 : *
47 : * Returns 0 on success and non zero on error. If it succeeds to
48 : * write to the seq_file it will reset the trace_seq, otherwise
49 : * it does not modify the trace_seq to let the caller try again.
50 : */
51 0 : int trace_print_seq(struct seq_file *m, struct trace_seq *s)
52 : {
53 0 : int ret;
54 :
55 0 : __trace_seq_init(s);
56 :
57 0 : ret = seq_buf_print_seq(m, &s->seq);
58 :
59 : /*
60 : * Only reset this buffer if we successfully wrote to the
61 : * seq_file buffer. This lets the caller try again or
62 : * do something else with the contents.
63 : */
64 0 : if (!ret)
65 0 : trace_seq_init(s);
66 :
67 0 : return ret;
68 : }
69 :
70 : /**
71 : * trace_seq_printf - sequence printing of trace information
72 : * @s: trace sequence descriptor
73 : * @fmt: printf format string
74 : *
75 : * The tracer may use either sequence operations or its own
76 : * copy to user routines. To simplify formating of a trace
77 : * trace_seq_printf() is used to store strings into a special
78 : * buffer (@s). Then the output may be either used by
79 : * the sequencer or pulled into another buffer.
80 : */
81 0 : void trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
82 : {
83 0 : unsigned int save_len = s->seq.len;
84 0 : va_list ap;
85 :
86 0 : if (s->full)
87 0 : return;
88 :
89 0 : __trace_seq_init(s);
90 :
91 0 : va_start(ap, fmt);
92 0 : seq_buf_vprintf(&s->seq, fmt, ap);
93 0 : va_end(ap);
94 :
95 : /* If we can't write it all, don't bother writing anything */
96 0 : if (unlikely(seq_buf_has_overflowed(&s->seq))) {
97 0 : s->seq.len = save_len;
98 0 : s->full = 1;
99 : }
100 : }
101 : EXPORT_SYMBOL_GPL(trace_seq_printf);
102 :
103 : /**
104 : * trace_seq_bitmask - write a bitmask array in its ASCII representation
105 : * @s: trace sequence descriptor
106 : * @maskp: points to an array of unsigned longs that represent a bitmask
107 : * @nmaskbits: The number of bits that are valid in @maskp
108 : *
109 : * Writes a ASCII representation of a bitmask string into @s.
110 : */
111 0 : void trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
112 : int nmaskbits)
113 : {
114 0 : unsigned int save_len = s->seq.len;
115 :
116 0 : if (s->full)
117 : return;
118 :
119 0 : __trace_seq_init(s);
120 :
121 0 : seq_buf_printf(&s->seq, "%*pb", nmaskbits, maskp);
122 :
123 0 : if (unlikely(seq_buf_has_overflowed(&s->seq))) {
124 0 : s->seq.len = save_len;
125 0 : s->full = 1;
126 : }
127 : }
128 : EXPORT_SYMBOL_GPL(trace_seq_bitmask);
129 :
130 : /**
131 : * trace_seq_vprintf - sequence printing of trace information
132 : * @s: trace sequence descriptor
133 : * @fmt: printf format string
134 : *
135 : * The tracer may use either sequence operations or its own
136 : * copy to user routines. To simplify formating of a trace
137 : * trace_seq_printf is used to store strings into a special
138 : * buffer (@s). Then the output may be either used by
139 : * the sequencer or pulled into another buffer.
140 : */
141 0 : void trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args)
142 : {
143 0 : unsigned int save_len = s->seq.len;
144 :
145 0 : if (s->full)
146 : return;
147 :
148 0 : __trace_seq_init(s);
149 :
150 0 : seq_buf_vprintf(&s->seq, fmt, args);
151 :
152 : /* If we can't write it all, don't bother writing anything */
153 0 : if (unlikely(seq_buf_has_overflowed(&s->seq))) {
154 0 : s->seq.len = save_len;
155 0 : s->full = 1;
156 : }
157 : }
158 : EXPORT_SYMBOL_GPL(trace_seq_vprintf);
159 :
160 : /**
161 : * trace_seq_bprintf - Write the printf string from binary arguments
162 : * @s: trace sequence descriptor
163 : * @fmt: The format string for the @binary arguments
164 : * @binary: The binary arguments for @fmt.
165 : *
166 : * When recording in a fast path, a printf may be recorded with just
167 : * saving the format and the arguments as they were passed to the
168 : * function, instead of wasting cycles converting the arguments into
169 : * ASCII characters. Instead, the arguments are saved in a 32 bit
170 : * word array that is defined by the format string constraints.
171 : *
172 : * This function will take the format and the binary array and finish
173 : * the conversion into the ASCII string within the buffer.
174 : */
175 0 : void trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary)
176 : {
177 0 : unsigned int save_len = s->seq.len;
178 :
179 0 : if (s->full)
180 : return;
181 :
182 0 : __trace_seq_init(s);
183 :
184 0 : seq_buf_bprintf(&s->seq, fmt, binary);
185 :
186 : /* If we can't write it all, don't bother writing anything */
187 0 : if (unlikely(seq_buf_has_overflowed(&s->seq))) {
188 0 : s->seq.len = save_len;
189 0 : s->full = 1;
190 0 : return;
191 : }
192 : }
193 : EXPORT_SYMBOL_GPL(trace_seq_bprintf);
194 :
195 : /**
196 : * trace_seq_puts - trace sequence printing of simple string
197 : * @s: trace sequence descriptor
198 : * @str: simple string to record
199 : *
200 : * The tracer may use either the sequence operations or its own
201 : * copy to user routines. This function records a simple string
202 : * into a special buffer (@s) for later retrieval by a sequencer
203 : * or other mechanism.
204 : */
205 0 : void trace_seq_puts(struct trace_seq *s, const char *str)
206 : {
207 0 : unsigned int len = strlen(str);
208 :
209 0 : if (s->full)
210 : return;
211 :
212 0 : __trace_seq_init(s);
213 :
214 0 : if (len > TRACE_SEQ_BUF_LEFT(s)) {
215 0 : s->full = 1;
216 0 : return;
217 : }
218 :
219 0 : seq_buf_putmem(&s->seq, str, len);
220 : }
221 : EXPORT_SYMBOL_GPL(trace_seq_puts);
222 :
223 : /**
224 : * trace_seq_putc - trace sequence printing of simple character
225 : * @s: trace sequence descriptor
226 : * @c: simple character to record
227 : *
228 : * The tracer may use either the sequence operations or its own
229 : * copy to user routines. This function records a simple charater
230 : * into a special buffer (@s) for later retrieval by a sequencer
231 : * or other mechanism.
232 : */
233 0 : void trace_seq_putc(struct trace_seq *s, unsigned char c)
234 : {
235 0 : if (s->full)
236 : return;
237 :
238 0 : __trace_seq_init(s);
239 :
240 0 : if (TRACE_SEQ_BUF_LEFT(s) < 1) {
241 0 : s->full = 1;
242 0 : return;
243 : }
244 :
245 0 : seq_buf_putc(&s->seq, c);
246 : }
247 : EXPORT_SYMBOL_GPL(trace_seq_putc);
248 :
249 : /**
250 : * trace_seq_putmem - write raw data into the trace_seq buffer
251 : * @s: trace sequence descriptor
252 : * @mem: The raw memory to copy into the buffer
253 : * @len: The length of the raw memory to copy (in bytes)
254 : *
255 : * There may be cases where raw memory needs to be written into the
256 : * buffer and a strcpy() would not work. Using this function allows
257 : * for such cases.
258 : */
259 0 : void trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len)
260 : {
261 0 : if (s->full)
262 : return;
263 :
264 0 : __trace_seq_init(s);
265 :
266 0 : if (len > TRACE_SEQ_BUF_LEFT(s)) {
267 0 : s->full = 1;
268 0 : return;
269 : }
270 :
271 0 : seq_buf_putmem(&s->seq, mem, len);
272 : }
273 : EXPORT_SYMBOL_GPL(trace_seq_putmem);
274 :
275 : /**
276 : * trace_seq_putmem_hex - write raw memory into the buffer in ASCII hex
277 : * @s: trace sequence descriptor
278 : * @mem: The raw memory to write its hex ASCII representation of
279 : * @len: The length of the raw memory to copy (in bytes)
280 : *
281 : * This is similar to trace_seq_putmem() except instead of just copying the
282 : * raw memory into the buffer it writes its ASCII representation of it
283 : * in hex characters.
284 : */
285 0 : void trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
286 : unsigned int len)
287 : {
288 0 : unsigned int save_len = s->seq.len;
289 :
290 0 : if (s->full)
291 : return;
292 :
293 0 : __trace_seq_init(s);
294 :
295 : /* Each byte is represented by two chars */
296 0 : if (len * 2 > TRACE_SEQ_BUF_LEFT(s)) {
297 0 : s->full = 1;
298 0 : return;
299 : }
300 :
301 : /* The added spaces can still cause an overflow */
302 0 : seq_buf_putmem_hex(&s->seq, mem, len);
303 :
304 0 : if (unlikely(seq_buf_has_overflowed(&s->seq))) {
305 0 : s->seq.len = save_len;
306 0 : s->full = 1;
307 0 : return;
308 : }
309 : }
310 : EXPORT_SYMBOL_GPL(trace_seq_putmem_hex);
311 :
312 : /**
313 : * trace_seq_path - copy a path into the sequence buffer
314 : * @s: trace sequence descriptor
315 : * @path: path to write into the sequence buffer.
316 : *
317 : * Write a path name into the sequence buffer.
318 : *
319 : * Returns 1 if we successfully written all the contents to
320 : * the buffer.
321 : * Returns 0 if we the length to write is bigger than the
322 : * reserved buffer space. In this case, nothing gets written.
323 : */
324 0 : int trace_seq_path(struct trace_seq *s, const struct path *path)
325 : {
326 0 : unsigned int save_len = s->seq.len;
327 :
328 0 : if (s->full)
329 : return 0;
330 :
331 0 : __trace_seq_init(s);
332 :
333 0 : if (TRACE_SEQ_BUF_LEFT(s) < 1) {
334 0 : s->full = 1;
335 0 : return 0;
336 : }
337 :
338 0 : seq_buf_path(&s->seq, path, "\n");
339 :
340 0 : if (unlikely(seq_buf_has_overflowed(&s->seq))) {
341 0 : s->seq.len = save_len;
342 0 : s->full = 1;
343 0 : return 0;
344 : }
345 :
346 : return 1;
347 : }
348 : EXPORT_SYMBOL_GPL(trace_seq_path);
349 :
350 : /**
351 : * trace_seq_to_user - copy the squence buffer to user space
352 : * @s: trace sequence descriptor
353 : * @ubuf: The userspace memory location to copy to
354 : * @cnt: The amount to copy
355 : *
356 : * Copies the sequence buffer into the userspace memory pointed to
357 : * by @ubuf. It starts from the last read position (@s->readpos)
358 : * and writes up to @cnt characters or till it reaches the end of
359 : * the content in the buffer (@s->len), which ever comes first.
360 : *
361 : * On success, it returns a positive number of the number of bytes
362 : * it copied.
363 : *
364 : * On failure it returns -EBUSY if all of the content in the
365 : * sequence has been already read, which includes nothing in the
366 : * sequenc (@s->len == @s->readpos).
367 : *
368 : * Returns -EFAULT if the copy to userspace fails.
369 : */
370 0 : int trace_seq_to_user(struct trace_seq *s, char __user *ubuf, int cnt)
371 : {
372 0 : __trace_seq_init(s);
373 0 : return seq_buf_to_user(&s->seq, ubuf, cnt);
374 : }
375 : EXPORT_SYMBOL_GPL(trace_seq_to_user);
376 :
377 0 : int trace_seq_hex_dump(struct trace_seq *s, const char *prefix_str,
378 : int prefix_type, int rowsize, int groupsize,
379 : const void *buf, size_t len, bool ascii)
380 : {
381 0 : unsigned int save_len = s->seq.len;
382 :
383 0 : if (s->full)
384 : return 0;
385 :
386 0 : __trace_seq_init(s);
387 :
388 0 : if (TRACE_SEQ_BUF_LEFT(s) < 1) {
389 0 : s->full = 1;
390 0 : return 0;
391 : }
392 :
393 0 : seq_buf_hex_dump(&(s->seq), prefix_str,
394 : prefix_type, rowsize, groupsize,
395 : buf, len, ascii);
396 :
397 0 : if (unlikely(seq_buf_has_overflowed(&s->seq))) {
398 0 : s->seq.len = save_len;
399 0 : s->full = 1;
400 0 : return 0;
401 : }
402 :
403 : return 1;
404 : }
405 : EXPORT_SYMBOL(trace_seq_hex_dump);
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