Commit | Line | Data |
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b7cdc182 | 1 | /* SPDX-License-Identifier: (GPL-2.0-only OR LGPL-2.1-only) |
9f36eaed | 2 | * |
24591303 | 3 | * ringbuffer/backend.h |
f3bc08c5 MD |
4 | * |
5 | * Ring buffer backend (API). | |
6 | * | |
886d51a3 MD |
7 | * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
8 | * | |
f3bc08c5 MD |
9 | * Credits to Steven Rostedt for proposing to use an extra-subbuffer owned by |
10 | * the reader in flight recorder mode. | |
11 | */ | |
12 | ||
9f36eaed MJ |
13 | #ifndef _LIB_RING_BUFFER_BACKEND_H |
14 | #define _LIB_RING_BUFFER_BACKEND_H | |
15 | ||
f3bc08c5 MD |
16 | #include <linux/types.h> |
17 | #include <linux/sched.h> | |
18 | #include <linux/timer.h> | |
19 | #include <linux/wait.h> | |
20 | #include <linux/poll.h> | |
21 | #include <linux/list.h> | |
22 | #include <linux/fs.h> | |
23 | #include <linux/mm.h> | |
80bb2600 | 24 | #include <wrapper/uaccess.h> |
924f4566 | 25 | #include <lttng/probe-user.h> |
f3bc08c5 MD |
26 | |
27 | /* Internal helpers */ | |
24591303 MD |
28 | #include <ringbuffer/backend_internal.h> |
29 | #include <ringbuffer/frontend_internal.h> | |
f3bc08c5 MD |
30 | |
31 | /* Ring buffer backend API */ | |
32 | ||
33 | /* Ring buffer backend access (read/write) */ | |
34 | ||
e20c0fec | 35 | extern size_t lib_ring_buffer_read(struct lttng_kernel_ring_buffer_backend *bufb, |
f3bc08c5 MD |
36 | size_t offset, void *dest, size_t len); |
37 | ||
e20c0fec | 38 | extern int __lib_ring_buffer_copy_to_user(struct lttng_kernel_ring_buffer_backend *bufb, |
f3bc08c5 MD |
39 | size_t offset, void __user *dest, |
40 | size_t len); | |
41 | ||
e20c0fec | 42 | extern int lib_ring_buffer_read_cstr(struct lttng_kernel_ring_buffer_backend *bufb, |
f3bc08c5 MD |
43 | size_t offset, void *dest, size_t len); |
44 | ||
0112cb7b | 45 | extern unsigned long * |
e20c0fec | 46 | lib_ring_buffer_read_get_pfn(struct lttng_kernel_ring_buffer_backend *bufb, size_t offset, |
f3bc08c5 MD |
47 | void ***virt); |
48 | ||
49 | /* | |
50 | * Return the address where a given offset is located. | |
51 | * Should be used to get the current subbuffer header pointer. Given we know | |
52 | * it's never on a page boundary, it's safe to write directly to this address, | |
53 | * as long as the write is never bigger than a page size. | |
54 | */ | |
55 | extern void * | |
e20c0fec | 56 | lib_ring_buffer_offset_address(struct lttng_kernel_ring_buffer_backend *bufb, |
f3bc08c5 MD |
57 | size_t offset); |
58 | extern void * | |
e20c0fec | 59 | lib_ring_buffer_read_offset_address(struct lttng_kernel_ring_buffer_backend *bufb, |
f3bc08c5 MD |
60 | size_t offset); |
61 | ||
62 | /** | |
63 | * lib_ring_buffer_write - write data to a buffer backend | |
64 | * @config : ring buffer instance configuration | |
65 | * @ctx: ring buffer context. (input arguments only) | |
66 | * @src : source pointer to copy from | |
67 | * @len : length of data to copy | |
68 | * | |
69 | * This function copies "len" bytes of data from a source pointer to a buffer | |
70 | * backend, at the current context offset. This is more or less a buffer | |
71 | * backend-specific memcpy() operation. Calls the slow path (_ring_buffer_write) | |
72 | * if copy is crossing a page boundary. | |
73 | */ | |
8617eb9a | 74 | static inline __attribute__((always_inline)) |
e20c0fec | 75 | void lib_ring_buffer_write(const struct lttng_kernel_ring_buffer_config *config, |
8a57ec02 | 76 | struct lttng_kernel_ring_buffer_ctx *ctx, |
f3bc08c5 MD |
77 | const void *src, size_t len) |
78 | { | |
e20c0fec | 79 | struct lttng_kernel_ring_buffer_backend *bufb = &ctx->priv.buf->backend; |
b1199bd3 | 80 | struct channel_backend *chanb = &ctx->priv.chan->backend; |
4774817f | 81 | size_t index, bytes_left_in_page; |
b1199bd3 | 82 | size_t offset = ctx->priv.buf_offset; |
e20c0fec | 83 | struct lttng_kernel_ring_buffer_backend_pages *backend_pages; |
f3bc08c5 | 84 | |
61eb4c39 MD |
85 | if (unlikely(!len)) |
86 | return; | |
85a07c33 MD |
87 | backend_pages = |
88 | lib_ring_buffer_get_backend_pages_from_ctx(config, ctx); | |
f3bc08c5 | 89 | offset &= chanb->buf_size - 1; |
f3bc08c5 | 90 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; |
4774817f MD |
91 | bytes_left_in_page = min_t(size_t, len, (-offset) & ~PAGE_MASK); |
92 | if (likely(bytes_left_in_page == len)) | |
f3bc08c5 | 93 | lib_ring_buffer_do_copy(config, |
85a07c33 | 94 | backend_pages->p[index].virt |
f3bc08c5 MD |
95 | + (offset & ~PAGE_MASK), |
96 | src, len); | |
97 | else | |
4774817f | 98 | _lib_ring_buffer_write(bufb, offset, src, len); |
b1199bd3 | 99 | ctx->priv.buf_offset += len; |
f3bc08c5 MD |
100 | } |
101 | ||
4ea00e4f JD |
102 | /** |
103 | * lib_ring_buffer_memset - write len bytes of c to a buffer backend | |
104 | * @config : ring buffer instance configuration | |
105 | * @bufb : ring buffer backend | |
106 | * @offset : offset within the buffer | |
107 | * @c : the byte to copy | |
108 | * @len : number of bytes to copy | |
109 | * | |
110 | * This function writes "len" bytes of "c" to a buffer backend, at a specific | |
111 | * offset. This is more or less a buffer backend-specific memset() operation. | |
112 | * Calls the slow path (_ring_buffer_memset) if write is crossing a page | |
113 | * boundary. | |
114 | */ | |
115 | static inline | |
e20c0fec | 116 | void lib_ring_buffer_memset(const struct lttng_kernel_ring_buffer_config *config, |
8a57ec02 | 117 | struct lttng_kernel_ring_buffer_ctx *ctx, int c, size_t len) |
4ea00e4f JD |
118 | { |
119 | ||
e20c0fec | 120 | struct lttng_kernel_ring_buffer_backend *bufb = &ctx->priv.buf->backend; |
b1199bd3 | 121 | struct channel_backend *chanb = &ctx->priv.chan->backend; |
4774817f | 122 | size_t index, bytes_left_in_page; |
b1199bd3 | 123 | size_t offset = ctx->priv.buf_offset; |
e20c0fec | 124 | struct lttng_kernel_ring_buffer_backend_pages *backend_pages; |
4ea00e4f | 125 | |
61eb4c39 MD |
126 | if (unlikely(!len)) |
127 | return; | |
85a07c33 MD |
128 | backend_pages = |
129 | lib_ring_buffer_get_backend_pages_from_ctx(config, ctx); | |
4ea00e4f | 130 | offset &= chanb->buf_size - 1; |
4ea00e4f | 131 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; |
4774817f MD |
132 | bytes_left_in_page = min_t(size_t, len, (-offset) & ~PAGE_MASK); |
133 | if (likely(bytes_left_in_page == len)) | |
85a07c33 | 134 | lib_ring_buffer_do_memset(backend_pages->p[index].virt |
4ea00e4f JD |
135 | + (offset & ~PAGE_MASK), |
136 | c, len); | |
137 | else | |
4774817f | 138 | _lib_ring_buffer_memset(bufb, offset, c, len); |
b1199bd3 | 139 | ctx->priv.buf_offset += len; |
4ea00e4f JD |
140 | } |
141 | ||
16f78f3a MD |
142 | /* |
143 | * Copy up to @len string bytes from @src to @dest. Stop whenever a NULL | |
144 | * terminating character is found in @src. Returns the number of bytes | |
145 | * copied. Does *not* terminate @dest with NULL terminating character. | |
146 | */ | |
d723e905 | 147 | static inline __attribute__((always_inline)) |
e20c0fec | 148 | size_t lib_ring_buffer_do_strcpy(const struct lttng_kernel_ring_buffer_config *config, |
16f78f3a MD |
149 | char *dest, const char *src, size_t len) |
150 | { | |
151 | size_t count; | |
152 | ||
153 | for (count = 0; count < len; count++) { | |
154 | char c; | |
155 | ||
156 | /* | |
157 | * Only read source character once, in case it is | |
158 | * modified concurrently. | |
159 | */ | |
585e5dcc | 160 | c = LTTNG_READ_ONCE(src[count]); |
16f78f3a MD |
161 | if (!c) |
162 | break; | |
163 | lib_ring_buffer_do_copy(config, &dest[count], &c, 1); | |
164 | } | |
165 | return count; | |
166 | } | |
167 | ||
168 | /* | |
169 | * Copy up to @len string bytes from @src to @dest. Stop whenever a NULL | |
170 | * terminating character is found in @src, or when a fault occurs. | |
171 | * Returns the number of bytes copied. Does *not* terminate @dest with | |
172 | * NULL terminating character. | |
173 | * | |
174 | * This function deals with userspace pointers, it should never be called | |
175 | * directly without having the src pointer checked with access_ok() | |
176 | * previously. | |
177 | */ | |
d723e905 | 178 | static inline __attribute__((always_inline)) |
e20c0fec | 179 | size_t lib_ring_buffer_do_strcpy_from_user_inatomic(const struct lttng_kernel_ring_buffer_config *config, |
16f78f3a MD |
180 | char *dest, const char __user *src, size_t len) |
181 | { | |
182 | size_t count; | |
183 | ||
184 | for (count = 0; count < len; count++) { | |
185 | int ret; | |
186 | char c; | |
187 | ||
f127e61e | 188 | ret = __copy_from_user_inatomic(&c, src + count, 1); |
16f78f3a MD |
189 | if (ret || !c) |
190 | break; | |
191 | lib_ring_buffer_do_copy(config, &dest[count], &c, 1); | |
192 | } | |
193 | return count; | |
194 | } | |
195 | ||
196 | /** | |
197 | * lib_ring_buffer_strcpy - write string data to a buffer backend | |
198 | * @config : ring buffer instance configuration | |
199 | * @ctx: ring buffer context. (input arguments only) | |
200 | * @src : source pointer to copy from | |
201 | * @len : length of data to copy | |
202 | * @pad : character to use for padding | |
203 | * | |
204 | * This function copies @len - 1 bytes of string data from a source | |
205 | * pointer to a buffer backend, followed by a terminating '\0' | |
206 | * character, at the current context offset. This is more or less a | |
207 | * buffer backend-specific strncpy() operation. If a terminating '\0' | |
208 | * character is found in @src before @len - 1 characters are copied, pad | |
209 | * the buffer with @pad characters (e.g. '#'). Calls the slow path | |
210 | * (_ring_buffer_strcpy) if copy is crossing a page boundary. | |
211 | */ | |
212 | static inline | |
e20c0fec | 213 | void lib_ring_buffer_strcpy(const struct lttng_kernel_ring_buffer_config *config, |
8a57ec02 | 214 | struct lttng_kernel_ring_buffer_ctx *ctx, |
16f78f3a MD |
215 | const char *src, size_t len, int pad) |
216 | { | |
e20c0fec | 217 | struct lttng_kernel_ring_buffer_backend *bufb = &ctx->priv.buf->backend; |
b1199bd3 | 218 | struct channel_backend *chanb = &ctx->priv.chan->backend; |
e5f1eb9a | 219 | size_t index, bytes_left_in_page; |
b1199bd3 | 220 | size_t offset = ctx->priv.buf_offset; |
e20c0fec | 221 | struct lttng_kernel_ring_buffer_backend_pages *backend_pages; |
16f78f3a MD |
222 | |
223 | if (unlikely(!len)) | |
224 | return; | |
85a07c33 MD |
225 | backend_pages = |
226 | lib_ring_buffer_get_backend_pages_from_ctx(config, ctx); | |
16f78f3a | 227 | offset &= chanb->buf_size - 1; |
16f78f3a | 228 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; |
e5f1eb9a MD |
229 | bytes_left_in_page = min_t(size_t, len, (-offset) & ~PAGE_MASK); |
230 | if (likely(bytes_left_in_page == len)) { | |
16f78f3a MD |
231 | size_t count; |
232 | ||
233 | count = lib_ring_buffer_do_strcpy(config, | |
85a07c33 | 234 | backend_pages->p[index].virt |
16f78f3a MD |
235 | + (offset & ~PAGE_MASK), |
236 | src, len - 1); | |
237 | offset += count; | |
238 | /* Padding */ | |
239 | if (unlikely(count < len - 1)) { | |
240 | size_t pad_len = len - 1 - count; | |
241 | ||
85a07c33 | 242 | lib_ring_buffer_do_memset(backend_pages->p[index].virt |
16f78f3a MD |
243 | + (offset & ~PAGE_MASK), |
244 | pad, pad_len); | |
245 | offset += pad_len; | |
246 | } | |
247 | /* Ending '\0' */ | |
85a07c33 | 248 | lib_ring_buffer_do_memset(backend_pages->p[index].virt |
16f78f3a MD |
249 | + (offset & ~PAGE_MASK), |
250 | '\0', 1); | |
251 | } else { | |
e5f1eb9a | 252 | _lib_ring_buffer_strcpy(bufb, offset, src, len, pad); |
16f78f3a | 253 | } |
b1199bd3 | 254 | ctx->priv.buf_offset += len; |
16f78f3a MD |
255 | } |
256 | ||
0d1080f4 MD |
257 | /** |
258 | * lib_ring_buffer_pstrcpy - write kernel C-string (input) to a buffer backend P-string | |
259 | * @config : ring buffer instance configuration | |
260 | * @ctx: ring buffer context. (input arguments only) | |
261 | * @src : source pointer to copy from | |
262 | * @len : length of data to copy | |
263 | * @pad : character to use for padding | |
264 | * | |
265 | * This function copies up to @len bytes of data from a source pointer | |
266 | * to a Pascal String into the buffer backend. If a terminating '\0' | |
267 | * character is found in @src before @len characters are copied, pad the | |
268 | * buffer with @pad characters (e.g. '\0'). | |
269 | * | |
270 | * The length of the pascal strings in the ring buffer is explicit: it | |
271 | * is either the array or sequence length. | |
272 | */ | |
273 | static inline | |
274 | void lib_ring_buffer_pstrcpy(const struct lttng_kernel_ring_buffer_config *config, | |
275 | struct lttng_kernel_ring_buffer_ctx *ctx, | |
276 | const char *src, size_t len, char pad) | |
277 | __attribute__((always_inline)); | |
278 | static inline | |
279 | void lib_ring_buffer_pstrcpy(const struct lttng_kernel_ring_buffer_config *config, | |
280 | struct lttng_kernel_ring_buffer_ctx *ctx, | |
281 | const char *src, size_t len, char pad) | |
282 | { | |
283 | struct lttng_kernel_ring_buffer_backend *bufb = &ctx->priv.buf->backend; | |
284 | struct channel_backend *chanb = &ctx->priv.chan->backend; | |
285 | size_t index, bytes_left_in_page; | |
286 | size_t offset = ctx->priv.buf_offset; | |
287 | struct lttng_kernel_ring_buffer_backend_pages *backend_pages; | |
288 | ||
289 | if (unlikely(!len)) | |
290 | return; | |
291 | backend_pages = | |
292 | lib_ring_buffer_get_backend_pages_from_ctx(config, ctx); | |
293 | offset &= chanb->buf_size - 1; | |
294 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; | |
295 | bytes_left_in_page = min_t(size_t, len, (-offset) & ~PAGE_MASK); | |
296 | if (likely(bytes_left_in_page == len)) { | |
297 | size_t count; | |
298 | ||
299 | count = lib_ring_buffer_do_strcpy(config, | |
300 | backend_pages->p[index].virt | |
301 | + (offset & ~PAGE_MASK), | |
302 | src, len); | |
303 | offset += count; | |
304 | /* Padding */ | |
305 | if (unlikely(count < len)) { | |
306 | size_t pad_len = len - count; | |
307 | ||
308 | lib_ring_buffer_do_memset(backend_pages->p[index].virt | |
309 | + (offset & ~PAGE_MASK), | |
310 | pad, pad_len); | |
311 | offset += pad_len; | |
312 | } | |
313 | } else { | |
314 | _lib_ring_buffer_pstrcpy(bufb, offset, src, len, pad); | |
315 | } | |
316 | ctx->priv.buf_offset += len; | |
317 | } | |
318 | ||
4ea00e4f | 319 | /** |
7b8ea3a5 | 320 | * lib_ring_buffer_copy_from_user_inatomic - write userspace data to a buffer backend |
4ea00e4f JD |
321 | * @config : ring buffer instance configuration |
322 | * @ctx: ring buffer context. (input arguments only) | |
323 | * @src : userspace source pointer to copy from | |
324 | * @len : length of data to copy | |
325 | * | |
326 | * This function copies "len" bytes of data from a userspace pointer to a | |
327 | * buffer backend, at the current context offset. This is more or less a buffer | |
328 | * backend-specific memcpy() operation. Calls the slow path | |
7b8ea3a5 MD |
329 | * (_ring_buffer_write_from_user_inatomic) if copy is crossing a page boundary. |
330 | * Disable the page fault handler to ensure we never try to take the mmap_sem. | |
4ea00e4f | 331 | */ |
d723e905 | 332 | static inline __attribute__((always_inline)) |
e20c0fec | 333 | void lib_ring_buffer_copy_from_user_inatomic(const struct lttng_kernel_ring_buffer_config *config, |
8a57ec02 | 334 | struct lttng_kernel_ring_buffer_ctx *ctx, |
4ea00e4f JD |
335 | const void __user *src, size_t len) |
336 | { | |
e20c0fec | 337 | struct lttng_kernel_ring_buffer_backend *bufb = &ctx->priv.buf->backend; |
b1199bd3 | 338 | struct channel_backend *chanb = &ctx->priv.chan->backend; |
4774817f | 339 | size_t index, bytes_left_in_page; |
b1199bd3 | 340 | size_t offset = ctx->priv.buf_offset; |
e20c0fec | 341 | struct lttng_kernel_ring_buffer_backend_pages *backend_pages; |
4ea00e4f JD |
342 | unsigned long ret; |
343 | ||
61eb4c39 MD |
344 | if (unlikely(!len)) |
345 | return; | |
85a07c33 MD |
346 | backend_pages = |
347 | lib_ring_buffer_get_backend_pages_from_ctx(config, ctx); | |
4ea00e4f | 348 | offset &= chanb->buf_size - 1; |
4ea00e4f | 349 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; |
4774817f | 350 | bytes_left_in_page = min_t(size_t, len, (-offset) & ~PAGE_MASK); |
4ea00e4f | 351 | |
80bb2600 | 352 | if (unlikely(!lttng_access_ok(VERIFY_READ, src, len))) |
4ea00e4f JD |
353 | goto fill_buffer; |
354 | ||
737afda6 | 355 | pagefault_disable(); |
4774817f | 356 | if (likely(bytes_left_in_page == len)) { |
7b8ea3a5 | 357 | ret = lib_ring_buffer_do_copy_from_user_inatomic( |
85a07c33 | 358 | backend_pages->p[index].virt + (offset & ~PAGE_MASK), |
4ea00e4f JD |
359 | src, len); |
360 | if (unlikely(ret > 0)) { | |
d87a9f03 | 361 | /* Copy failed. */ |
737afda6 | 362 | goto fill_buffer_enable_pf; |
4ea00e4f JD |
363 | } |
364 | } else { | |
4774817f | 365 | _lib_ring_buffer_copy_from_user_inatomic(bufb, offset, src, len); |
4ea00e4f | 366 | } |
7b8ea3a5 | 367 | pagefault_enable(); |
b1199bd3 | 368 | ctx->priv.buf_offset += len; |
4ea00e4f JD |
369 | |
370 | return; | |
371 | ||
737afda6 | 372 | fill_buffer_enable_pf: |
7b8ea3a5 | 373 | pagefault_enable(); |
737afda6 | 374 | fill_buffer: |
4ea00e4f JD |
375 | /* |
376 | * In the error path we call the slow path version to avoid | |
377 | * the pollution of static inline code. | |
378 | */ | |
4774817f | 379 | _lib_ring_buffer_memset(bufb, offset, 0, len); |
26d46aeb | 380 | ctx->priv.buf_offset += len; |
4ea00e4f JD |
381 | } |
382 | ||
16f78f3a MD |
383 | /** |
384 | * lib_ring_buffer_strcpy_from_user_inatomic - write userspace string data to a buffer backend | |
385 | * @config : ring buffer instance configuration | |
386 | * @ctx: ring buffer context (input arguments only) | |
387 | * @src : userspace source pointer to copy from | |
388 | * @len : length of data to copy | |
389 | * @pad : character to use for padding | |
390 | * | |
391 | * This function copies @len - 1 bytes of string data from a userspace | |
392 | * source pointer to a buffer backend, followed by a terminating '\0' | |
393 | * character, at the current context offset. This is more or less a | |
394 | * buffer backend-specific strncpy() operation. If a terminating '\0' | |
395 | * character is found in @src before @len - 1 characters are copied, pad | |
396 | * the buffer with @pad characters (e.g. '#'). Calls the slow path | |
397 | * (_ring_buffer_strcpy_from_user_inatomic) if copy is crossing a page | |
398 | * boundary. Disable the page fault handler to ensure we never try to | |
399 | * take the mmap_sem. | |
400 | */ | |
401 | static inline | |
e20c0fec | 402 | void lib_ring_buffer_strcpy_from_user_inatomic(const struct lttng_kernel_ring_buffer_config *config, |
8a57ec02 | 403 | struct lttng_kernel_ring_buffer_ctx *ctx, |
16f78f3a MD |
404 | const void __user *src, size_t len, int pad) |
405 | { | |
e20c0fec | 406 | struct lttng_kernel_ring_buffer_backend *bufb = &ctx->priv.buf->backend; |
b1199bd3 | 407 | struct channel_backend *chanb = &ctx->priv.chan->backend; |
e5f1eb9a | 408 | size_t index, bytes_left_in_page; |
b1199bd3 | 409 | size_t offset = ctx->priv.buf_offset; |
e20c0fec | 410 | struct lttng_kernel_ring_buffer_backend_pages *backend_pages; |
16f78f3a MD |
411 | |
412 | if (unlikely(!len)) | |
413 | return; | |
85a07c33 MD |
414 | backend_pages = |
415 | lib_ring_buffer_get_backend_pages_from_ctx(config, ctx); | |
16f78f3a | 416 | offset &= chanb->buf_size - 1; |
16f78f3a | 417 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; |
e5f1eb9a | 418 | bytes_left_in_page = min_t(size_t, len, (-offset) & ~PAGE_MASK); |
16f78f3a | 419 | |
80bb2600 | 420 | if (unlikely(!lttng_access_ok(VERIFY_READ, src, len))) |
16f78f3a MD |
421 | goto fill_buffer; |
422 | ||
737afda6 | 423 | pagefault_disable(); |
e5f1eb9a | 424 | if (likely(bytes_left_in_page == len)) { |
16f78f3a MD |
425 | size_t count; |
426 | ||
427 | count = lib_ring_buffer_do_strcpy_from_user_inatomic(config, | |
85a07c33 | 428 | backend_pages->p[index].virt |
16f78f3a MD |
429 | + (offset & ~PAGE_MASK), |
430 | src, len - 1); | |
431 | offset += count; | |
432 | /* Padding */ | |
433 | if (unlikely(count < len - 1)) { | |
434 | size_t pad_len = len - 1 - count; | |
435 | ||
85a07c33 | 436 | lib_ring_buffer_do_memset(backend_pages->p[index].virt |
16f78f3a MD |
437 | + (offset & ~PAGE_MASK), |
438 | pad, pad_len); | |
439 | offset += pad_len; | |
440 | } | |
441 | /* Ending '\0' */ | |
85a07c33 | 442 | lib_ring_buffer_do_memset(backend_pages->p[index].virt |
16f78f3a MD |
443 | + (offset & ~PAGE_MASK), |
444 | '\0', 1); | |
445 | } else { | |
446 | _lib_ring_buffer_strcpy_from_user_inatomic(bufb, offset, src, | |
e5f1eb9a | 447 | len, pad); |
16f78f3a MD |
448 | } |
449 | pagefault_enable(); | |
b1199bd3 | 450 | ctx->priv.buf_offset += len; |
16f78f3a MD |
451 | |
452 | return; | |
453 | ||
454 | fill_buffer: | |
16f78f3a MD |
455 | /* |
456 | * In the error path we call the slow path version to avoid | |
457 | * the pollution of static inline code. | |
458 | */ | |
4774817f | 459 | _lib_ring_buffer_memset(bufb, offset, pad, len - 1); |
16f78f3a | 460 | offset += len - 1; |
4774817f | 461 | _lib_ring_buffer_memset(bufb, offset, '\0', 1); |
26d46aeb | 462 | ctx->priv.buf_offset += len; |
16f78f3a MD |
463 | } |
464 | ||
0d1080f4 MD |
465 | /** |
466 | * lib_ring_buffer_pstrcpy_from_user_inatomic - write user-space C-string (input) to a buffer backend P-string | |
467 | * @config : ring buffer instance configuration | |
468 | * @ctx: ring buffer context. (input arguments only) | |
469 | * @src : source pointer to copy from | |
470 | * @len : length of data to copy | |
471 | * @pad : character to use for padding | |
472 | * | |
473 | * This function copies up to @len bytes of data from a source pointer | |
474 | * to a Pascal String into the buffer backend. If a terminating '\0' | |
475 | * character is found in @src before @len characters are copied, pad the | |
476 | * buffer with @pad characters (e.g. '\0'). | |
477 | * | |
478 | * The length of the pascal strings in the ring buffer is explicit: it | |
479 | * is either the array or sequence length. | |
480 | */ | |
481 | static inline | |
482 | void lib_ring_buffer_pstrcpy_from_user_inatomic(const struct lttng_kernel_ring_buffer_config *config, | |
483 | struct lttng_kernel_ring_buffer_ctx *ctx, | |
484 | const char __user *src, size_t len, char pad) | |
485 | __attribute__((always_inline)); | |
486 | static inline | |
487 | void lib_ring_buffer_pstrcpy_from_user_inatomic(const struct lttng_kernel_ring_buffer_config *config, | |
488 | struct lttng_kernel_ring_buffer_ctx *ctx, | |
489 | const char __user *src, size_t len, char pad) | |
490 | { | |
491 | struct lttng_kernel_ring_buffer_backend *bufb = &ctx->priv.buf->backend; | |
492 | struct channel_backend *chanb = &ctx->priv.chan->backend; | |
493 | size_t index, bytes_left_in_page; | |
494 | size_t offset = ctx->priv.buf_offset; | |
495 | struct lttng_kernel_ring_buffer_backend_pages *backend_pages; | |
496 | ||
497 | if (unlikely(!len)) | |
498 | return; | |
499 | backend_pages = | |
500 | lib_ring_buffer_get_backend_pages_from_ctx(config, ctx); | |
501 | offset &= chanb->buf_size - 1; | |
502 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; | |
503 | bytes_left_in_page = min_t(size_t, len, (-offset) & ~PAGE_MASK); | |
504 | ||
505 | if (unlikely(!lttng_access_ok(VERIFY_READ, src, len))) | |
506 | goto fill_buffer; | |
507 | ||
508 | pagefault_disable(); | |
509 | if (likely(bytes_left_in_page == len)) { | |
510 | size_t count; | |
511 | ||
512 | count = lib_ring_buffer_do_strcpy_from_user_inatomic(config, | |
513 | backend_pages->p[index].virt | |
514 | + (offset & ~PAGE_MASK), | |
515 | src, len); | |
516 | offset += count; | |
517 | /* Padding */ | |
518 | if (unlikely(count < len)) { | |
519 | size_t pad_len = len - count; | |
520 | ||
521 | lib_ring_buffer_do_memset(backend_pages->p[index].virt | |
522 | + (offset & ~PAGE_MASK), | |
523 | pad, pad_len); | |
524 | offset += pad_len; | |
525 | } | |
526 | } else { | |
527 | _lib_ring_buffer_pstrcpy_from_user_inatomic(bufb, offset, src, len, pad); | |
528 | } | |
529 | ctx->priv.buf_offset += len; | |
530 | pagefault_enable(); | |
531 | ||
532 | return; | |
533 | ||
534 | fill_buffer: | |
535 | /* | |
536 | * In the error path we call the slow path version to avoid | |
537 | * the pollution of static inline code. | |
538 | */ | |
4774817f | 539 | _lib_ring_buffer_memset(bufb, offset, pad, len); |
0d1080f4 MD |
540 | ctx->priv.buf_offset += len; |
541 | } | |
542 | ||
f3bc08c5 MD |
543 | /* |
544 | * This accessor counts the number of unread records in a buffer. | |
545 | * It only provides a consistent value if no reads not writes are performed | |
546 | * concurrently. | |
547 | */ | |
548 | static inline | |
549 | unsigned long lib_ring_buffer_get_records_unread( | |
e20c0fec MD |
550 | const struct lttng_kernel_ring_buffer_config *config, |
551 | struct lttng_kernel_ring_buffer *buf) | |
f3bc08c5 | 552 | { |
e20c0fec MD |
553 | struct lttng_kernel_ring_buffer_backend *bufb = &buf->backend; |
554 | struct lttng_kernel_ring_buffer_backend_pages *pages; | |
f3bc08c5 MD |
555 | unsigned long records_unread = 0, sb_bindex, id; |
556 | unsigned int i; | |
557 | ||
558 | for (i = 0; i < bufb->chan->backend.num_subbuf; i++) { | |
559 | id = bufb->buf_wsb[i].id; | |
560 | sb_bindex = subbuffer_id_get_index(config, id); | |
561 | pages = bufb->array[sb_bindex]; | |
562 | records_unread += v_read(config, &pages->records_unread); | |
563 | } | |
564 | if (config->mode == RING_BUFFER_OVERWRITE) { | |
565 | id = bufb->buf_rsb.id; | |
566 | sb_bindex = subbuffer_id_get_index(config, id); | |
567 | pages = bufb->array[sb_bindex]; | |
568 | records_unread += v_read(config, &pages->records_unread); | |
569 | } | |
570 | return records_unread; | |
571 | } | |
572 | ||
3c8ebbc8 MD |
573 | /* |
574 | * We use __copy_from_user_inatomic to copy userspace data after | |
575 | * checking with access_ok() and disabling page faults. | |
576 | * | |
577 | * Return 0 if OK, nonzero on error. | |
578 | */ | |
579 | static inline | |
580 | unsigned long lib_ring_buffer_copy_from_user_check_nofault(void *dest, | |
581 | const void __user *src, | |
582 | unsigned long len) | |
583 | { | |
924f4566 | 584 | return lttng_copy_from_user_check_nofault(dest, src, len); |
3c8ebbc8 MD |
585 | } |
586 | ||
886d51a3 | 587 | #endif /* _LIB_RING_BUFFER_BACKEND_H */ |