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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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