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886d51a3 MD |
1 | #ifndef _LIB_RING_BUFFER_BACKEND_H |
2 | #define _LIB_RING_BUFFER_BACKEND_H | |
f3bc08c5 MD |
3 | |
4 | /* | |
886d51a3 | 5 | * lib/ringbuffer/backend.h |
f3bc08c5 MD |
6 | * |
7 | * Ring buffer backend (API). | |
8 | * | |
886d51a3 MD |
9 | * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
10 | * | |
11 | * This library is free software; you can redistribute it and/or | |
12 | * modify it under the terms of the GNU Lesser General Public | |
13 | * License as published by the Free Software Foundation; only | |
14 | * version 2.1 of the License. | |
15 | * | |
16 | * This library is distributed in the hope that it will be useful, | |
17 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
18 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
19 | * Lesser General Public License for more details. | |
20 | * | |
21 | * You should have received a copy of the GNU Lesser General Public | |
22 | * License along with this library; if not, write to the Free Software | |
23 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
f3bc08c5 MD |
24 | * |
25 | * Credits to Steven Rostedt for proposing to use an extra-subbuffer owned by | |
26 | * the reader in flight recorder mode. | |
27 | */ | |
28 | ||
29 | #include <linux/types.h> | |
30 | #include <linux/sched.h> | |
31 | #include <linux/timer.h> | |
32 | #include <linux/wait.h> | |
33 | #include <linux/poll.h> | |
34 | #include <linux/list.h> | |
35 | #include <linux/fs.h> | |
36 | #include <linux/mm.h> | |
7b8ea3a5 | 37 | #include <linux/uaccess.h> |
f3bc08c5 MD |
38 | |
39 | /* Internal helpers */ | |
40 | #include "../../wrapper/ringbuffer/backend_internal.h" | |
41 | #include "../../wrapper/ringbuffer/frontend_internal.h" | |
42 | ||
43 | /* Ring buffer backend API */ | |
44 | ||
45 | /* Ring buffer backend access (read/write) */ | |
46 | ||
47 | extern size_t lib_ring_buffer_read(struct lib_ring_buffer_backend *bufb, | |
48 | size_t offset, void *dest, size_t len); | |
49 | ||
50 | extern int __lib_ring_buffer_copy_to_user(struct lib_ring_buffer_backend *bufb, | |
51 | size_t offset, void __user *dest, | |
52 | size_t len); | |
53 | ||
54 | extern int lib_ring_buffer_read_cstr(struct lib_ring_buffer_backend *bufb, | |
55 | size_t offset, void *dest, size_t len); | |
56 | ||
57 | extern struct page ** | |
58 | lib_ring_buffer_read_get_page(struct lib_ring_buffer_backend *bufb, size_t offset, | |
59 | void ***virt); | |
60 | ||
61 | /* | |
62 | * Return the address where a given offset is located. | |
63 | * Should be used to get the current subbuffer header pointer. Given we know | |
64 | * it's never on a page boundary, it's safe to write directly to this address, | |
65 | * as long as the write is never bigger than a page size. | |
66 | */ | |
67 | extern void * | |
68 | lib_ring_buffer_offset_address(struct lib_ring_buffer_backend *bufb, | |
69 | size_t offset); | |
70 | extern void * | |
71 | lib_ring_buffer_read_offset_address(struct lib_ring_buffer_backend *bufb, | |
72 | size_t offset); | |
73 | ||
74 | /** | |
75 | * lib_ring_buffer_write - write data to a buffer backend | |
76 | * @config : ring buffer instance configuration | |
77 | * @ctx: ring buffer context. (input arguments only) | |
78 | * @src : source pointer to copy from | |
79 | * @len : length of data to copy | |
80 | * | |
81 | * This function copies "len" bytes of data from a source pointer to a buffer | |
82 | * backend, at the current context offset. This is more or less a buffer | |
83 | * backend-specific memcpy() operation. Calls the slow path (_ring_buffer_write) | |
84 | * if copy is crossing a page boundary. | |
85 | */ | |
86 | static inline | |
87 | void lib_ring_buffer_write(const struct lib_ring_buffer_config *config, | |
88 | struct lib_ring_buffer_ctx *ctx, | |
89 | const void *src, size_t len) | |
90 | { | |
91 | struct lib_ring_buffer_backend *bufb = &ctx->buf->backend; | |
92 | struct channel_backend *chanb = &ctx->chan->backend; | |
93 | size_t sbidx, index; | |
94 | size_t offset = ctx->buf_offset; | |
95 | ssize_t pagecpy; | |
96 | struct lib_ring_buffer_backend_pages *rpages; | |
97 | unsigned long sb_bindex, id; | |
98 | ||
61eb4c39 MD |
99 | if (unlikely(!len)) |
100 | return; | |
f3bc08c5 MD |
101 | offset &= chanb->buf_size - 1; |
102 | sbidx = offset >> chanb->subbuf_size_order; | |
103 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; | |
104 | pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK); | |
105 | id = bufb->buf_wsb[sbidx].id; | |
106 | sb_bindex = subbuffer_id_get_index(config, id); | |
107 | rpages = bufb->array[sb_bindex]; | |
108 | CHAN_WARN_ON(ctx->chan, | |
109 | config->mode == RING_BUFFER_OVERWRITE | |
110 | && subbuffer_id_is_noref(config, id)); | |
111 | if (likely(pagecpy == len)) | |
112 | lib_ring_buffer_do_copy(config, | |
113 | rpages->p[index].virt | |
114 | + (offset & ~PAGE_MASK), | |
115 | src, len); | |
116 | else | |
117 | _lib_ring_buffer_write(bufb, offset, src, len, 0); | |
118 | ctx->buf_offset += len; | |
119 | } | |
120 | ||
4ea00e4f JD |
121 | /** |
122 | * lib_ring_buffer_memset - write len bytes of c to a buffer backend | |
123 | * @config : ring buffer instance configuration | |
124 | * @bufb : ring buffer backend | |
125 | * @offset : offset within the buffer | |
126 | * @c : the byte to copy | |
127 | * @len : number of bytes to copy | |
128 | * | |
129 | * This function writes "len" bytes of "c" to a buffer backend, at a specific | |
130 | * offset. This is more or less a buffer backend-specific memset() operation. | |
131 | * Calls the slow path (_ring_buffer_memset) if write is crossing a page | |
132 | * boundary. | |
133 | */ | |
134 | static inline | |
135 | void lib_ring_buffer_memset(const struct lib_ring_buffer_config *config, | |
136 | struct lib_ring_buffer_ctx *ctx, int c, size_t len) | |
137 | { | |
138 | ||
139 | struct lib_ring_buffer_backend *bufb = &ctx->buf->backend; | |
140 | struct channel_backend *chanb = &ctx->chan->backend; | |
141 | size_t sbidx, index; | |
142 | size_t offset = ctx->buf_offset; | |
143 | ssize_t pagecpy; | |
144 | struct lib_ring_buffer_backend_pages *rpages; | |
145 | unsigned long sb_bindex, id; | |
146 | ||
61eb4c39 MD |
147 | if (unlikely(!len)) |
148 | return; | |
4ea00e4f JD |
149 | offset &= chanb->buf_size - 1; |
150 | sbidx = offset >> chanb->subbuf_size_order; | |
151 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; | |
152 | pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK); | |
153 | id = bufb->buf_wsb[sbidx].id; | |
154 | sb_bindex = subbuffer_id_get_index(config, id); | |
155 | rpages = bufb->array[sb_bindex]; | |
156 | CHAN_WARN_ON(ctx->chan, | |
157 | config->mode == RING_BUFFER_OVERWRITE | |
158 | && subbuffer_id_is_noref(config, id)); | |
159 | if (likely(pagecpy == len)) | |
160 | lib_ring_buffer_do_memset(rpages->p[index].virt | |
161 | + (offset & ~PAGE_MASK), | |
162 | c, len); | |
163 | else | |
164 | _lib_ring_buffer_memset(bufb, offset, c, len, 0); | |
165 | ctx->buf_offset += len; | |
166 | } | |
167 | ||
16f78f3a MD |
168 | /* |
169 | * Copy up to @len string bytes from @src to @dest. Stop whenever a NULL | |
170 | * terminating character is found in @src. Returns the number of bytes | |
171 | * copied. Does *not* terminate @dest with NULL terminating character. | |
172 | */ | |
173 | static inline | |
174 | size_t lib_ring_buffer_do_strcpy(const struct lib_ring_buffer_config *config, | |
175 | char *dest, const char *src, size_t len) | |
176 | { | |
177 | size_t count; | |
178 | ||
179 | for (count = 0; count < len; count++) { | |
180 | char c; | |
181 | ||
182 | /* | |
183 | * Only read source character once, in case it is | |
184 | * modified concurrently. | |
185 | */ | |
186 | c = ACCESS_ONCE(src[count]); | |
187 | if (!c) | |
188 | break; | |
189 | lib_ring_buffer_do_copy(config, &dest[count], &c, 1); | |
190 | } | |
191 | return count; | |
192 | } | |
193 | ||
194 | /* | |
195 | * Copy up to @len string bytes from @src to @dest. Stop whenever a NULL | |
196 | * terminating character is found in @src, or when a fault occurs. | |
197 | * Returns the number of bytes copied. Does *not* terminate @dest with | |
198 | * NULL terminating character. | |
199 | * | |
200 | * This function deals with userspace pointers, it should never be called | |
201 | * directly without having the src pointer checked with access_ok() | |
202 | * previously. | |
203 | */ | |
204 | static inline | |
205 | size_t lib_ring_buffer_do_strcpy_from_user_inatomic(const struct lib_ring_buffer_config *config, | |
206 | char *dest, const char __user *src, size_t len) | |
207 | { | |
208 | size_t count; | |
209 | ||
210 | for (count = 0; count < len; count++) { | |
211 | int ret; | |
212 | char c; | |
213 | ||
214 | ret = __get_user(c, &src[count]); | |
215 | if (ret || !c) | |
216 | break; | |
217 | lib_ring_buffer_do_copy(config, &dest[count], &c, 1); | |
218 | } | |
219 | return count; | |
220 | } | |
221 | ||
222 | /** | |
223 | * lib_ring_buffer_strcpy - write string data to a buffer backend | |
224 | * @config : ring buffer instance configuration | |
225 | * @ctx: ring buffer context. (input arguments only) | |
226 | * @src : source pointer to copy from | |
227 | * @len : length of data to copy | |
228 | * @pad : character to use for padding | |
229 | * | |
230 | * This function copies @len - 1 bytes of string data from a source | |
231 | * pointer to a buffer backend, followed by a terminating '\0' | |
232 | * character, at the current context offset. This is more or less a | |
233 | * buffer backend-specific strncpy() operation. If a terminating '\0' | |
234 | * character is found in @src before @len - 1 characters are copied, pad | |
235 | * the buffer with @pad characters (e.g. '#'). Calls the slow path | |
236 | * (_ring_buffer_strcpy) if copy is crossing a page boundary. | |
237 | */ | |
238 | static inline | |
239 | void lib_ring_buffer_strcpy(const struct lib_ring_buffer_config *config, | |
240 | struct lib_ring_buffer_ctx *ctx, | |
241 | const char *src, size_t len, int pad) | |
242 | { | |
243 | struct lib_ring_buffer_backend *bufb = &ctx->buf->backend; | |
244 | struct channel_backend *chanb = &ctx->chan->backend; | |
245 | size_t sbidx, index, pagecpy; | |
246 | size_t offset = ctx->buf_offset; | |
247 | struct lib_ring_buffer_backend_pages *rpages; | |
248 | unsigned long sb_bindex, id; | |
249 | ||
250 | if (unlikely(!len)) | |
251 | return; | |
252 | offset &= chanb->buf_size - 1; | |
253 | sbidx = offset >> chanb->subbuf_size_order; | |
254 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; | |
255 | pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK); | |
256 | id = bufb->buf_wsb[sbidx].id; | |
257 | sb_bindex = subbuffer_id_get_index(config, id); | |
258 | rpages = bufb->array[sb_bindex]; | |
259 | CHAN_WARN_ON(ctx->chan, | |
260 | config->mode == RING_BUFFER_OVERWRITE | |
261 | && subbuffer_id_is_noref(config, id)); | |
262 | if (likely(pagecpy == len)) { | |
263 | size_t count; | |
264 | ||
265 | count = lib_ring_buffer_do_strcpy(config, | |
266 | rpages->p[index].virt | |
267 | + (offset & ~PAGE_MASK), | |
268 | src, len - 1); | |
269 | offset += count; | |
270 | /* Padding */ | |
271 | if (unlikely(count < len - 1)) { | |
272 | size_t pad_len = len - 1 - count; | |
273 | ||
274 | lib_ring_buffer_do_memset(rpages->p[index].virt | |
275 | + (offset & ~PAGE_MASK), | |
276 | pad, pad_len); | |
277 | offset += pad_len; | |
278 | } | |
279 | /* Ending '\0' */ | |
280 | lib_ring_buffer_do_memset(rpages->p[index].virt | |
281 | + (offset & ~PAGE_MASK), | |
282 | '\0', 1); | |
283 | } else { | |
284 | _lib_ring_buffer_strcpy(bufb, offset, src, len, 0, pad); | |
285 | } | |
286 | ctx->buf_offset += len; | |
287 | } | |
288 | ||
4ea00e4f | 289 | /** |
7b8ea3a5 | 290 | * lib_ring_buffer_copy_from_user_inatomic - write userspace data to a buffer backend |
4ea00e4f JD |
291 | * @config : ring buffer instance configuration |
292 | * @ctx: ring buffer context. (input arguments only) | |
293 | * @src : userspace source pointer to copy from | |
294 | * @len : length of data to copy | |
295 | * | |
296 | * This function copies "len" bytes of data from a userspace pointer to a | |
297 | * buffer backend, at the current context offset. This is more or less a buffer | |
298 | * backend-specific memcpy() operation. Calls the slow path | |
7b8ea3a5 MD |
299 | * (_ring_buffer_write_from_user_inatomic) if copy is crossing a page boundary. |
300 | * Disable the page fault handler to ensure we never try to take the mmap_sem. | |
4ea00e4f JD |
301 | */ |
302 | static inline | |
7b8ea3a5 | 303 | void lib_ring_buffer_copy_from_user_inatomic(const struct lib_ring_buffer_config *config, |
4ea00e4f JD |
304 | struct lib_ring_buffer_ctx *ctx, |
305 | const void __user *src, size_t len) | |
306 | { | |
307 | struct lib_ring_buffer_backend *bufb = &ctx->buf->backend; | |
308 | struct channel_backend *chanb = &ctx->chan->backend; | |
309 | size_t sbidx, index; | |
310 | size_t offset = ctx->buf_offset; | |
311 | ssize_t pagecpy; | |
312 | struct lib_ring_buffer_backend_pages *rpages; | |
313 | unsigned long sb_bindex, id; | |
314 | unsigned long ret; | |
7b8ea3a5 | 315 | mm_segment_t old_fs = get_fs(); |
4ea00e4f | 316 | |
61eb4c39 MD |
317 | if (unlikely(!len)) |
318 | return; | |
4ea00e4f JD |
319 | offset &= chanb->buf_size - 1; |
320 | sbidx = offset >> chanb->subbuf_size_order; | |
321 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; | |
322 | pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK); | |
323 | id = bufb->buf_wsb[sbidx].id; | |
324 | sb_bindex = subbuffer_id_get_index(config, id); | |
325 | rpages = bufb->array[sb_bindex]; | |
326 | CHAN_WARN_ON(ctx->chan, | |
327 | config->mode == RING_BUFFER_OVERWRITE | |
328 | && subbuffer_id_is_noref(config, id)); | |
329 | ||
7b8ea3a5 MD |
330 | set_fs(KERNEL_DS); |
331 | pagefault_disable(); | |
4ea00e4f JD |
332 | if (unlikely(!access_ok(VERIFY_READ, src, len))) |
333 | goto fill_buffer; | |
334 | ||
335 | if (likely(pagecpy == len)) { | |
7b8ea3a5 | 336 | ret = lib_ring_buffer_do_copy_from_user_inatomic( |
4ea00e4f JD |
337 | rpages->p[index].virt + (offset & ~PAGE_MASK), |
338 | src, len); | |
339 | if (unlikely(ret > 0)) { | |
340 | len -= (pagecpy - ret); | |
341 | offset += (pagecpy - ret); | |
342 | goto fill_buffer; | |
343 | } | |
344 | } else { | |
7b8ea3a5 | 345 | _lib_ring_buffer_copy_from_user_inatomic(bufb, offset, src, len, 0); |
4ea00e4f | 346 | } |
7b8ea3a5 MD |
347 | pagefault_enable(); |
348 | set_fs(old_fs); | |
4ea00e4f JD |
349 | ctx->buf_offset += len; |
350 | ||
351 | return; | |
352 | ||
353 | fill_buffer: | |
7b8ea3a5 MD |
354 | pagefault_enable(); |
355 | set_fs(old_fs); | |
4ea00e4f JD |
356 | /* |
357 | * In the error path we call the slow path version to avoid | |
358 | * the pollution of static inline code. | |
359 | */ | |
360 | _lib_ring_buffer_memset(bufb, offset, 0, len, 0); | |
361 | } | |
362 | ||
16f78f3a MD |
363 | /** |
364 | * lib_ring_buffer_strcpy_from_user_inatomic - write userspace string data to a buffer backend | |
365 | * @config : ring buffer instance configuration | |
366 | * @ctx: ring buffer context (input arguments only) | |
367 | * @src : userspace source pointer to copy from | |
368 | * @len : length of data to copy | |
369 | * @pad : character to use for padding | |
370 | * | |
371 | * This function copies @len - 1 bytes of string data from a userspace | |
372 | * source pointer to a buffer backend, followed by a terminating '\0' | |
373 | * character, at the current context offset. This is more or less a | |
374 | * buffer backend-specific strncpy() operation. If a terminating '\0' | |
375 | * character is found in @src before @len - 1 characters are copied, pad | |
376 | * the buffer with @pad characters (e.g. '#'). Calls the slow path | |
377 | * (_ring_buffer_strcpy_from_user_inatomic) if copy is crossing a page | |
378 | * boundary. Disable the page fault handler to ensure we never try to | |
379 | * take the mmap_sem. | |
380 | */ | |
381 | static inline | |
382 | void lib_ring_buffer_strcpy_from_user_inatomic(const struct lib_ring_buffer_config *config, | |
383 | struct lib_ring_buffer_ctx *ctx, | |
384 | const void __user *src, size_t len, int pad) | |
385 | { | |
386 | struct lib_ring_buffer_backend *bufb = &ctx->buf->backend; | |
387 | struct channel_backend *chanb = &ctx->chan->backend; | |
388 | size_t sbidx, index, pagecpy; | |
389 | size_t offset = ctx->buf_offset; | |
390 | struct lib_ring_buffer_backend_pages *rpages; | |
391 | unsigned long sb_bindex, id; | |
392 | mm_segment_t old_fs = get_fs(); | |
393 | ||
394 | if (unlikely(!len)) | |
395 | return; | |
396 | offset &= chanb->buf_size - 1; | |
397 | sbidx = offset >> chanb->subbuf_size_order; | |
398 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; | |
399 | pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK); | |
400 | id = bufb->buf_wsb[sbidx].id; | |
401 | sb_bindex = subbuffer_id_get_index(config, id); | |
402 | rpages = bufb->array[sb_bindex]; | |
403 | CHAN_WARN_ON(ctx->chan, | |
404 | config->mode == RING_BUFFER_OVERWRITE | |
405 | && subbuffer_id_is_noref(config, id)); | |
406 | ||
407 | set_fs(KERNEL_DS); | |
408 | pagefault_disable(); | |
409 | if (unlikely(!access_ok(VERIFY_READ, src, len))) | |
410 | goto fill_buffer; | |
411 | ||
412 | if (likely(pagecpy == len)) { | |
413 | size_t count; | |
414 | ||
415 | count = lib_ring_buffer_do_strcpy_from_user_inatomic(config, | |
416 | rpages->p[index].virt | |
417 | + (offset & ~PAGE_MASK), | |
418 | src, len - 1); | |
419 | offset += count; | |
420 | /* Padding */ | |
421 | if (unlikely(count < len - 1)) { | |
422 | size_t pad_len = len - 1 - count; | |
423 | ||
424 | lib_ring_buffer_do_memset(rpages->p[index].virt | |
425 | + (offset & ~PAGE_MASK), | |
426 | pad, pad_len); | |
427 | offset += pad_len; | |
428 | } | |
429 | /* Ending '\0' */ | |
430 | lib_ring_buffer_do_memset(rpages->p[index].virt | |
431 | + (offset & ~PAGE_MASK), | |
432 | '\0', 1); | |
433 | } else { | |
434 | _lib_ring_buffer_strcpy_from_user_inatomic(bufb, offset, src, | |
435 | len, 0, pad); | |
436 | } | |
437 | pagefault_enable(); | |
438 | set_fs(old_fs); | |
439 | ctx->buf_offset += len; | |
440 | ||
441 | return; | |
442 | ||
443 | fill_buffer: | |
444 | pagefault_enable(); | |
445 | set_fs(old_fs); | |
446 | /* | |
447 | * In the error path we call the slow path version to avoid | |
448 | * the pollution of static inline code. | |
449 | */ | |
450 | _lib_ring_buffer_memset(bufb, offset, pad, len - 1, 0); | |
451 | offset += len - 1; | |
452 | _lib_ring_buffer_memset(bufb, offset, '\0', 1, 0); | |
453 | } | |
454 | ||
f3bc08c5 MD |
455 | /* |
456 | * This accessor counts the number of unread records in a buffer. | |
457 | * It only provides a consistent value if no reads not writes are performed | |
458 | * concurrently. | |
459 | */ | |
460 | static inline | |
461 | unsigned long lib_ring_buffer_get_records_unread( | |
462 | const struct lib_ring_buffer_config *config, | |
463 | struct lib_ring_buffer *buf) | |
464 | { | |
465 | struct lib_ring_buffer_backend *bufb = &buf->backend; | |
466 | struct lib_ring_buffer_backend_pages *pages; | |
467 | unsigned long records_unread = 0, sb_bindex, id; | |
468 | unsigned int i; | |
469 | ||
470 | for (i = 0; i < bufb->chan->backend.num_subbuf; i++) { | |
471 | id = bufb->buf_wsb[i].id; | |
472 | sb_bindex = subbuffer_id_get_index(config, id); | |
473 | pages = bufb->array[sb_bindex]; | |
474 | records_unread += v_read(config, &pages->records_unread); | |
475 | } | |
476 | if (config->mode == RING_BUFFER_OVERWRITE) { | |
477 | id = bufb->buf_rsb.id; | |
478 | sb_bindex = subbuffer_id_get_index(config, id); | |
479 | pages = bufb->array[sb_bindex]; | |
480 | records_unread += v_read(config, &pages->records_unread); | |
481 | } | |
482 | return records_unread; | |
483 | } | |
484 | ||
886d51a3 | 485 | #endif /* _LIB_RING_BUFFER_BACKEND_H */ |