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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 | ||
99 | offset &= chanb->buf_size - 1; | |
100 | sbidx = offset >> chanb->subbuf_size_order; | |
101 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; | |
102 | pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK); | |
103 | id = bufb->buf_wsb[sbidx].id; | |
104 | sb_bindex = subbuffer_id_get_index(config, id); | |
105 | rpages = bufb->array[sb_bindex]; | |
106 | CHAN_WARN_ON(ctx->chan, | |
107 | config->mode == RING_BUFFER_OVERWRITE | |
108 | && subbuffer_id_is_noref(config, id)); | |
109 | if (likely(pagecpy == len)) | |
110 | lib_ring_buffer_do_copy(config, | |
111 | rpages->p[index].virt | |
112 | + (offset & ~PAGE_MASK), | |
113 | src, len); | |
114 | else | |
115 | _lib_ring_buffer_write(bufb, offset, src, len, 0); | |
116 | ctx->buf_offset += len; | |
117 | } | |
118 | ||
4ea00e4f JD |
119 | /** |
120 | * lib_ring_buffer_memset - write len bytes of c to a buffer backend | |
121 | * @config : ring buffer instance configuration | |
122 | * @bufb : ring buffer backend | |
123 | * @offset : offset within the buffer | |
124 | * @c : the byte to copy | |
125 | * @len : number of bytes to copy | |
126 | * | |
127 | * This function writes "len" bytes of "c" to a buffer backend, at a specific | |
128 | * offset. This is more or less a buffer backend-specific memset() operation. | |
129 | * Calls the slow path (_ring_buffer_memset) if write is crossing a page | |
130 | * boundary. | |
131 | */ | |
132 | static inline | |
133 | void lib_ring_buffer_memset(const struct lib_ring_buffer_config *config, | |
134 | struct lib_ring_buffer_ctx *ctx, int c, size_t len) | |
135 | { | |
136 | ||
137 | struct lib_ring_buffer_backend *bufb = &ctx->buf->backend; | |
138 | struct channel_backend *chanb = &ctx->chan->backend; | |
139 | size_t sbidx, index; | |
140 | size_t offset = ctx->buf_offset; | |
141 | ssize_t pagecpy; | |
142 | struct lib_ring_buffer_backend_pages *rpages; | |
143 | unsigned long sb_bindex, id; | |
144 | ||
145 | offset &= chanb->buf_size - 1; | |
146 | sbidx = offset >> chanb->subbuf_size_order; | |
147 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; | |
148 | pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK); | |
149 | id = bufb->buf_wsb[sbidx].id; | |
150 | sb_bindex = subbuffer_id_get_index(config, id); | |
151 | rpages = bufb->array[sb_bindex]; | |
152 | CHAN_WARN_ON(ctx->chan, | |
153 | config->mode == RING_BUFFER_OVERWRITE | |
154 | && subbuffer_id_is_noref(config, id)); | |
155 | if (likely(pagecpy == len)) | |
156 | lib_ring_buffer_do_memset(rpages->p[index].virt | |
157 | + (offset & ~PAGE_MASK), | |
158 | c, len); | |
159 | else | |
160 | _lib_ring_buffer_memset(bufb, offset, c, len, 0); | |
161 | ctx->buf_offset += len; | |
162 | } | |
163 | ||
164 | /** | |
7b8ea3a5 | 165 | * lib_ring_buffer_copy_from_user_inatomic - write userspace data to a buffer backend |
4ea00e4f JD |
166 | * @config : ring buffer instance configuration |
167 | * @ctx: ring buffer context. (input arguments only) | |
168 | * @src : userspace source pointer to copy from | |
169 | * @len : length of data to copy | |
170 | * | |
171 | * This function copies "len" bytes of data from a userspace pointer to a | |
172 | * buffer backend, at the current context offset. This is more or less a buffer | |
173 | * backend-specific memcpy() operation. Calls the slow path | |
7b8ea3a5 MD |
174 | * (_ring_buffer_write_from_user_inatomic) if copy is crossing a page boundary. |
175 | * Disable the page fault handler to ensure we never try to take the mmap_sem. | |
4ea00e4f JD |
176 | */ |
177 | static inline | |
7b8ea3a5 | 178 | void lib_ring_buffer_copy_from_user_inatomic(const struct lib_ring_buffer_config *config, |
4ea00e4f JD |
179 | struct lib_ring_buffer_ctx *ctx, |
180 | const void __user *src, size_t len) | |
181 | { | |
182 | struct lib_ring_buffer_backend *bufb = &ctx->buf->backend; | |
183 | struct channel_backend *chanb = &ctx->chan->backend; | |
184 | size_t sbidx, index; | |
185 | size_t offset = ctx->buf_offset; | |
186 | ssize_t pagecpy; | |
187 | struct lib_ring_buffer_backend_pages *rpages; | |
188 | unsigned long sb_bindex, id; | |
189 | unsigned long ret; | |
7b8ea3a5 | 190 | mm_segment_t old_fs = get_fs(); |
4ea00e4f JD |
191 | |
192 | offset &= chanb->buf_size - 1; | |
193 | sbidx = offset >> chanb->subbuf_size_order; | |
194 | index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; | |
195 | pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK); | |
196 | id = bufb->buf_wsb[sbidx].id; | |
197 | sb_bindex = subbuffer_id_get_index(config, id); | |
198 | rpages = bufb->array[sb_bindex]; | |
199 | CHAN_WARN_ON(ctx->chan, | |
200 | config->mode == RING_BUFFER_OVERWRITE | |
201 | && subbuffer_id_is_noref(config, id)); | |
202 | ||
7b8ea3a5 MD |
203 | set_fs(KERNEL_DS); |
204 | pagefault_disable(); | |
4ea00e4f JD |
205 | if (unlikely(!access_ok(VERIFY_READ, src, len))) |
206 | goto fill_buffer; | |
207 | ||
208 | if (likely(pagecpy == len)) { | |
7b8ea3a5 | 209 | ret = lib_ring_buffer_do_copy_from_user_inatomic( |
4ea00e4f JD |
210 | rpages->p[index].virt + (offset & ~PAGE_MASK), |
211 | src, len); | |
212 | if (unlikely(ret > 0)) { | |
213 | len -= (pagecpy - ret); | |
214 | offset += (pagecpy - ret); | |
215 | goto fill_buffer; | |
216 | } | |
217 | } else { | |
7b8ea3a5 | 218 | _lib_ring_buffer_copy_from_user_inatomic(bufb, offset, src, len, 0); |
4ea00e4f | 219 | } |
7b8ea3a5 MD |
220 | pagefault_enable(); |
221 | set_fs(old_fs); | |
4ea00e4f JD |
222 | ctx->buf_offset += len; |
223 | ||
224 | return; | |
225 | ||
226 | fill_buffer: | |
7b8ea3a5 MD |
227 | pagefault_enable(); |
228 | set_fs(old_fs); | |
4ea00e4f JD |
229 | /* |
230 | * In the error path we call the slow path version to avoid | |
231 | * the pollution of static inline code. | |
232 | */ | |
233 | _lib_ring_buffer_memset(bufb, offset, 0, len, 0); | |
234 | } | |
235 | ||
f3bc08c5 MD |
236 | /* |
237 | * This accessor counts the number of unread records in a buffer. | |
238 | * It only provides a consistent value if no reads not writes are performed | |
239 | * concurrently. | |
240 | */ | |
241 | static inline | |
242 | unsigned long lib_ring_buffer_get_records_unread( | |
243 | const struct lib_ring_buffer_config *config, | |
244 | struct lib_ring_buffer *buf) | |
245 | { | |
246 | struct lib_ring_buffer_backend *bufb = &buf->backend; | |
247 | struct lib_ring_buffer_backend_pages *pages; | |
248 | unsigned long records_unread = 0, sb_bindex, id; | |
249 | unsigned int i; | |
250 | ||
251 | for (i = 0; i < bufb->chan->backend.num_subbuf; i++) { | |
252 | id = bufb->buf_wsb[i].id; | |
253 | sb_bindex = subbuffer_id_get_index(config, id); | |
254 | pages = bufb->array[sb_bindex]; | |
255 | records_unread += v_read(config, &pages->records_unread); | |
256 | } | |
257 | if (config->mode == RING_BUFFER_OVERWRITE) { | |
258 | id = bufb->buf_rsb.id; | |
259 | sb_bindex = subbuffer_id_get_index(config, id); | |
260 | pages = bufb->array[sb_bindex]; | |
261 | records_unread += v_read(config, &pages->records_unread); | |
262 | } | |
263 | return records_unread; | |
264 | } | |
265 | ||
266 | ssize_t lib_ring_buffer_file_splice_read(struct file *in, loff_t *ppos, | |
267 | struct pipe_inode_info *pipe, | |
268 | size_t len, unsigned int flags); | |
269 | loff_t lib_ring_buffer_no_llseek(struct file *file, loff_t offset, int origin); | |
270 | ||
886d51a3 | 271 | #endif /* _LIB_RING_BUFFER_BACKEND_H */ |