1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * A generic kernel FIFO implementation
4 *
5 * Copyright (C) 2009/2010 Stefani Seibold <stefani@seibold.net>
6 */
7
8 #include <linux/kernel.h>
9 #include <linux/export.h>
10 #include <linux/slab.h>
11 #include <linux/err.h>
12 #include <linux/log2.h>
13 #include <linux/uaccess.h>
14 #include <linux/kfifo.h>
15
16 /*
17 * internal helper to calculate the unused elements in a fifo
18 */
kfifo_unused(struct __kfifo * fifo)19 static inline unsigned int kfifo_unused(struct __kfifo *fifo)
20 {
21 return (fifo->mask + 1) - (fifo->in - fifo->out);
22 }
23
__kfifo_alloc(struct __kfifo * fifo,unsigned int size,size_t esize,gfp_t gfp_mask)24 int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
25 size_t esize, gfp_t gfp_mask)
26 {
27 /*
28 * round up to the next power of 2, since our 'let the indices
29 * wrap' technique works only in this case.
30 */
31 size = roundup_pow_of_two(size);
32
33 fifo->in = 0;
34 fifo->out = 0;
35 fifo->esize = esize;
36
37 if (size < 2) {
38 fifo->data = NULL;
39 fifo->mask = 0;
40 return -EINVAL;
41 }
42
43 fifo->data = kmalloc_array(esize, size, gfp_mask);
44
45 if (!fifo->data) {
46 fifo->mask = 0;
47 return -ENOMEM;
48 }
49 fifo->mask = size - 1;
50
51 return 0;
52 }
53 EXPORT_SYMBOL(__kfifo_alloc);
54
__kfifo_free(struct __kfifo * fifo)55 void __kfifo_free(struct __kfifo *fifo)
56 {
57 kfree(fifo->data);
58 fifo->in = 0;
59 fifo->out = 0;
60 fifo->esize = 0;
61 fifo->data = NULL;
62 fifo->mask = 0;
63 }
64 EXPORT_SYMBOL(__kfifo_free);
65
__kfifo_init(struct __kfifo * fifo,void * buffer,unsigned int size,size_t esize)66 int __kfifo_init(struct __kfifo *fifo, void *buffer,
67 unsigned int size, size_t esize)
68 {
69 size /= esize;
70
71 if (!is_power_of_2(size))
72 size = rounddown_pow_of_two(size);
73
74 fifo->in = 0;
75 fifo->out = 0;
76 fifo->esize = esize;
77 fifo->data = buffer;
78
79 if (size < 2) {
80 fifo->mask = 0;
81 return -EINVAL;
82 }
83 fifo->mask = size - 1;
84
85 return 0;
86 }
87 EXPORT_SYMBOL(__kfifo_init);
88
kfifo_copy_in(struct __kfifo * fifo,const void * src,unsigned int len,unsigned int off)89 static void kfifo_copy_in(struct __kfifo *fifo, const void *src,
90 unsigned int len, unsigned int off)
91 {
92 unsigned int size = fifo->mask + 1;
93 unsigned int esize = fifo->esize;
94 unsigned int l;
95
96 off &= fifo->mask;
97 if (esize != 1) {
98 off *= esize;
99 size *= esize;
100 len *= esize;
101 }
102 l = min(len, size - off);
103
104 memcpy(fifo->data + off, src, l);
105 memcpy(fifo->data, src + l, len - l);
106 /*
107 * make sure that the data in the fifo is up to date before
108 * incrementing the fifo->in index counter
109 */
110 smp_wmb();
111 }
112
__kfifo_in(struct __kfifo * fifo,const void * buf,unsigned int len)113 unsigned int __kfifo_in(struct __kfifo *fifo,
114 const void *buf, unsigned int len)
115 {
116 unsigned int l;
117
118 l = kfifo_unused(fifo);
119 if (len > l)
120 len = l;
121
122 kfifo_copy_in(fifo, buf, len, fifo->in);
123 fifo->in += len;
124 return len;
125 }
126 EXPORT_SYMBOL(__kfifo_in);
127
kfifo_copy_out(struct __kfifo * fifo,void * dst,unsigned int len,unsigned int off)128 static void kfifo_copy_out(struct __kfifo *fifo, void *dst,
129 unsigned int len, unsigned int off)
130 {
131 unsigned int size = fifo->mask + 1;
132 unsigned int esize = fifo->esize;
133 unsigned int l;
134
135 off &= fifo->mask;
136 if (esize != 1) {
137 off *= esize;
138 size *= esize;
139 len *= esize;
140 }
141 l = min(len, size - off);
142
143 memcpy(dst, fifo->data + off, l);
144 memcpy(dst + l, fifo->data, len - l);
145 /*
146 * make sure that the data is copied before
147 * incrementing the fifo->out index counter
148 */
149 smp_wmb();
150 }
151
__kfifo_out_peek(struct __kfifo * fifo,void * buf,unsigned int len)152 unsigned int __kfifo_out_peek(struct __kfifo *fifo,
153 void *buf, unsigned int len)
154 {
155 unsigned int l;
156
157 l = fifo->in - fifo->out;
158 if (len > l)
159 len = l;
160
161 kfifo_copy_out(fifo, buf, len, fifo->out);
162 return len;
163 }
164 EXPORT_SYMBOL(__kfifo_out_peek);
165
__kfifo_out(struct __kfifo * fifo,void * buf,unsigned int len)166 unsigned int __kfifo_out(struct __kfifo *fifo,
167 void *buf, unsigned int len)
168 {
169 len = __kfifo_out_peek(fifo, buf, len);
170 fifo->out += len;
171 return len;
172 }
173 EXPORT_SYMBOL(__kfifo_out);
174
kfifo_copy_from_user(struct __kfifo * fifo,const void __user * from,unsigned int len,unsigned int off,unsigned int * copied)175 static unsigned long kfifo_copy_from_user(struct __kfifo *fifo,
176 const void __user *from, unsigned int len, unsigned int off,
177 unsigned int *copied)
178 {
179 unsigned int size = fifo->mask + 1;
180 unsigned int esize = fifo->esize;
181 unsigned int l;
182 unsigned long ret;
183
184 off &= fifo->mask;
185 if (esize != 1) {
186 off *= esize;
187 size *= esize;
188 len *= esize;
189 }
190 l = min(len, size - off);
191
192 ret = copy_from_user(fifo->data + off, from, l);
193 if (unlikely(ret))
194 ret = DIV_ROUND_UP(ret + len - l, esize);
195 else {
196 ret = copy_from_user(fifo->data, from + l, len - l);
197 if (unlikely(ret))
198 ret = DIV_ROUND_UP(ret, esize);
199 }
200 /*
201 * make sure that the data in the fifo is up to date before
202 * incrementing the fifo->in index counter
203 */
204 smp_wmb();
205 *copied = len - ret * esize;
206 /* return the number of elements which are not copied */
207 return ret;
208 }
209
__kfifo_from_user(struct __kfifo * fifo,const void __user * from,unsigned long len,unsigned int * copied)210 int __kfifo_from_user(struct __kfifo *fifo, const void __user *from,
211 unsigned long len, unsigned int *copied)
212 {
213 unsigned int l;
214 unsigned long ret;
215 unsigned int esize = fifo->esize;
216 int err;
217
218 if (esize != 1)
219 len /= esize;
220
221 l = kfifo_unused(fifo);
222 if (len > l)
223 len = l;
224
225 ret = kfifo_copy_from_user(fifo, from, len, fifo->in, copied);
226 if (unlikely(ret)) {
227 len -= ret;
228 err = -EFAULT;
229 } else
230 err = 0;
231 fifo->in += len;
232 return err;
233 }
234 EXPORT_SYMBOL(__kfifo_from_user);
235
kfifo_copy_to_user(struct __kfifo * fifo,void __user * to,unsigned int len,unsigned int off,unsigned int * copied)236 static unsigned long kfifo_copy_to_user(struct __kfifo *fifo, void __user *to,
237 unsigned int len, unsigned int off, unsigned int *copied)
238 {
239 unsigned int l;
240 unsigned long ret;
241 unsigned int size = fifo->mask + 1;
242 unsigned int esize = fifo->esize;
243
244 off &= fifo->mask;
245 if (esize != 1) {
246 off *= esize;
247 size *= esize;
248 len *= esize;
249 }
250 l = min(len, size - off);
251
252 ret = copy_to_user(to, fifo->data + off, l);
253 if (unlikely(ret))
254 ret = DIV_ROUND_UP(ret + len - l, esize);
255 else {
256 ret = copy_to_user(to + l, fifo->data, len - l);
257 if (unlikely(ret))
258 ret = DIV_ROUND_UP(ret, esize);
259 }
260 /*
261 * make sure that the data is copied before
262 * incrementing the fifo->out index counter
263 */
264 smp_wmb();
265 *copied = len - ret * esize;
266 /* return the number of elements which are not copied */
267 return ret;
268 }
269
__kfifo_to_user(struct __kfifo * fifo,void __user * to,unsigned long len,unsigned int * copied)270 int __kfifo_to_user(struct __kfifo *fifo, void __user *to,
271 unsigned long len, unsigned int *copied)
272 {
273 unsigned int l;
274 unsigned long ret;
275 unsigned int esize = fifo->esize;
276 int err;
277
278 if (esize != 1)
279 len /= esize;
280
281 l = fifo->in - fifo->out;
282 if (len > l)
283 len = l;
284 ret = kfifo_copy_to_user(fifo, to, len, fifo->out, copied);
285 if (unlikely(ret)) {
286 len -= ret;
287 err = -EFAULT;
288 } else
289 err = 0;
290 fifo->out += len;
291 return err;
292 }
293 EXPORT_SYMBOL(__kfifo_to_user);
294
setup_sgl_buf(struct scatterlist * sgl,void * buf,int nents,unsigned int len)295 static int setup_sgl_buf(struct scatterlist *sgl, void *buf,
296 int nents, unsigned int len)
297 {
298 int n;
299 unsigned int l;
300 unsigned int off;
301 struct page *page;
302
303 if (!nents)
304 return 0;
305
306 if (!len)
307 return 0;
308
309 n = 0;
310 page = virt_to_page(buf);
311 off = offset_in_page(buf);
312 l = 0;
313
314 while (len >= l + PAGE_SIZE - off) {
315 struct page *npage;
316
317 l += PAGE_SIZE;
318 buf += PAGE_SIZE;
319 npage = virt_to_page(buf);
320 if (page_to_phys(page) != page_to_phys(npage) - l) {
321 sg_set_page(sgl, page, l - off, off);
322 sgl = sg_next(sgl);
323 if (++n == nents || sgl == NULL)
324 return n;
325 page = npage;
326 len -= l - off;
327 l = off = 0;
328 }
329 }
330 sg_set_page(sgl, page, len, off);
331 return n + 1;
332 }
333
setup_sgl(struct __kfifo * fifo,struct scatterlist * sgl,int nents,unsigned int len,unsigned int off)334 static unsigned int setup_sgl(struct __kfifo *fifo, struct scatterlist *sgl,
335 int nents, unsigned int len, unsigned int off)
336 {
337 unsigned int size = fifo->mask + 1;
338 unsigned int esize = fifo->esize;
339 unsigned int l;
340 unsigned int n;
341
342 off &= fifo->mask;
343 if (esize != 1) {
344 off *= esize;
345 size *= esize;
346 len *= esize;
347 }
348 l = min(len, size - off);
349
350 n = setup_sgl_buf(sgl, fifo->data + off, nents, l);
351 n += setup_sgl_buf(sgl + n, fifo->data, nents - n, len - l);
352
353 return n;
354 }
355
__kfifo_dma_in_prepare(struct __kfifo * fifo,struct scatterlist * sgl,int nents,unsigned int len)356 unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,
357 struct scatterlist *sgl, int nents, unsigned int len)
358 {
359 unsigned int l;
360
361 l = kfifo_unused(fifo);
362 if (len > l)
363 len = l;
364
365 return setup_sgl(fifo, sgl, nents, len, fifo->in);
366 }
367 EXPORT_SYMBOL(__kfifo_dma_in_prepare);
368
__kfifo_dma_out_prepare(struct __kfifo * fifo,struct scatterlist * sgl,int nents,unsigned int len)369 unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,
370 struct scatterlist *sgl, int nents, unsigned int len)
371 {
372 unsigned int l;
373
374 l = fifo->in - fifo->out;
375 if (len > l)
376 len = l;
377
378 return setup_sgl(fifo, sgl, nents, len, fifo->out);
379 }
380 EXPORT_SYMBOL(__kfifo_dma_out_prepare);
381
__kfifo_max_r(unsigned int len,size_t recsize)382 unsigned int __kfifo_max_r(unsigned int len, size_t recsize)
383 {
384 unsigned int max = (1 << (recsize << 3)) - 1;
385
386 if (len > max)
387 return max;
388 return len;
389 }
390 EXPORT_SYMBOL(__kfifo_max_r);
391
392 #define __KFIFO_PEEK(data, out, mask) \
393 ((data)[(out) & (mask)])
394 /*
395 * __kfifo_peek_n internal helper function for determinate the length of
396 * the next record in the fifo
397 */
__kfifo_peek_n(struct __kfifo * fifo,size_t recsize)398 static unsigned int __kfifo_peek_n(struct __kfifo *fifo, size_t recsize)
399 {
400 unsigned int l;
401 unsigned int mask = fifo->mask;
402 unsigned char *data = fifo->data;
403
404 l = __KFIFO_PEEK(data, fifo->out, mask);
405
406 if (--recsize)
407 l |= __KFIFO_PEEK(data, fifo->out + 1, mask) << 8;
408
409 return l;
410 }
411
412 #define __KFIFO_POKE(data, in, mask, val) \
413 ( \
414 (data)[(in) & (mask)] = (unsigned char)(val) \
415 )
416
417 /*
418 * __kfifo_poke_n internal helper function for storeing the length of
419 * the record into the fifo
420 */
__kfifo_poke_n(struct __kfifo * fifo,unsigned int n,size_t recsize)421 static void __kfifo_poke_n(struct __kfifo *fifo, unsigned int n, size_t recsize)
422 {
423 unsigned int mask = fifo->mask;
424 unsigned char *data = fifo->data;
425
426 __KFIFO_POKE(data, fifo->in, mask, n);
427
428 if (recsize > 1)
429 __KFIFO_POKE(data, fifo->in + 1, mask, n >> 8);
430 }
431
__kfifo_len_r(struct __kfifo * fifo,size_t recsize)432 unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize)
433 {
434 return __kfifo_peek_n(fifo, recsize);
435 }
436 EXPORT_SYMBOL(__kfifo_len_r);
437
__kfifo_in_r(struct __kfifo * fifo,const void * buf,unsigned int len,size_t recsize)438 unsigned int __kfifo_in_r(struct __kfifo *fifo, const void *buf,
439 unsigned int len, size_t recsize)
440 {
441 if (len + recsize > kfifo_unused(fifo))
442 return 0;
443
444 __kfifo_poke_n(fifo, len, recsize);
445
446 kfifo_copy_in(fifo, buf, len, fifo->in + recsize);
447 fifo->in += len + recsize;
448 return len;
449 }
450 EXPORT_SYMBOL(__kfifo_in_r);
451
kfifo_out_copy_r(struct __kfifo * fifo,void * buf,unsigned int len,size_t recsize,unsigned int * n)452 static unsigned int kfifo_out_copy_r(struct __kfifo *fifo,
453 void *buf, unsigned int len, size_t recsize, unsigned int *n)
454 {
455 *n = __kfifo_peek_n(fifo, recsize);
456
457 if (len > *n)
458 len = *n;
459
460 kfifo_copy_out(fifo, buf, len, fifo->out + recsize);
461 return len;
462 }
463
__kfifo_out_peek_r(struct __kfifo * fifo,void * buf,unsigned int len,size_t recsize)464 unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf,
465 unsigned int len, size_t recsize)
466 {
467 unsigned int n;
468
469 if (fifo->in == fifo->out)
470 return 0;
471
472 return kfifo_out_copy_r(fifo, buf, len, recsize, &n);
473 }
474 EXPORT_SYMBOL(__kfifo_out_peek_r);
475
__kfifo_out_r(struct __kfifo * fifo,void * buf,unsigned int len,size_t recsize)476 unsigned int __kfifo_out_r(struct __kfifo *fifo, void *buf,
477 unsigned int len, size_t recsize)
478 {
479 unsigned int n;
480
481 if (fifo->in == fifo->out)
482 return 0;
483
484 len = kfifo_out_copy_r(fifo, buf, len, recsize, &n);
485 fifo->out += n + recsize;
486 return len;
487 }
488 EXPORT_SYMBOL(__kfifo_out_r);
489
__kfifo_skip_r(struct __kfifo * fifo,size_t recsize)490 void __kfifo_skip_r(struct __kfifo *fifo, size_t recsize)
491 {
492 unsigned int n;
493
494 n = __kfifo_peek_n(fifo, recsize);
495 fifo->out += n + recsize;
496 }
497 EXPORT_SYMBOL(__kfifo_skip_r);
498
__kfifo_from_user_r(struct __kfifo * fifo,const void __user * from,unsigned long len,unsigned int * copied,size_t recsize)499 int __kfifo_from_user_r(struct __kfifo *fifo, const void __user *from,
500 unsigned long len, unsigned int *copied, size_t recsize)
501 {
502 unsigned long ret;
503
504 len = __kfifo_max_r(len, recsize);
505
506 if (len + recsize > kfifo_unused(fifo)) {
507 *copied = 0;
508 return 0;
509 }
510
511 __kfifo_poke_n(fifo, len, recsize);
512
513 ret = kfifo_copy_from_user(fifo, from, len, fifo->in + recsize, copied);
514 if (unlikely(ret)) {
515 *copied = 0;
516 return -EFAULT;
517 }
518 fifo->in += len + recsize;
519 return 0;
520 }
521 EXPORT_SYMBOL(__kfifo_from_user_r);
522
__kfifo_to_user_r(struct __kfifo * fifo,void __user * to,unsigned long len,unsigned int * copied,size_t recsize)523 int __kfifo_to_user_r(struct __kfifo *fifo, void __user *to,
524 unsigned long len, unsigned int *copied, size_t recsize)
525 {
526 unsigned long ret;
527 unsigned int n;
528
529 if (fifo->in == fifo->out) {
530 *copied = 0;
531 return 0;
532 }
533
534 n = __kfifo_peek_n(fifo, recsize);
535 if (len > n)
536 len = n;
537
538 ret = kfifo_copy_to_user(fifo, to, len, fifo->out + recsize, copied);
539 if (unlikely(ret)) {
540 *copied = 0;
541 return -EFAULT;
542 }
543 fifo->out += n + recsize;
544 return 0;
545 }
546 EXPORT_SYMBOL(__kfifo_to_user_r);
547
__kfifo_dma_in_prepare_r(struct __kfifo * fifo,struct scatterlist * sgl,int nents,unsigned int len,size_t recsize)548 unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
549 struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
550 {
551 BUG_ON(!nents);
552
553 len = __kfifo_max_r(len, recsize);
554
555 if (len + recsize > kfifo_unused(fifo))
556 return 0;
557
558 return setup_sgl(fifo, sgl, nents, len, fifo->in + recsize);
559 }
560 EXPORT_SYMBOL(__kfifo_dma_in_prepare_r);
561
__kfifo_dma_in_finish_r(struct __kfifo * fifo,unsigned int len,size_t recsize)562 void __kfifo_dma_in_finish_r(struct __kfifo *fifo,
563 unsigned int len, size_t recsize)
564 {
565 len = __kfifo_max_r(len, recsize);
566 __kfifo_poke_n(fifo, len, recsize);
567 fifo->in += len + recsize;
568 }
569 EXPORT_SYMBOL(__kfifo_dma_in_finish_r);
570
__kfifo_dma_out_prepare_r(struct __kfifo * fifo,struct scatterlist * sgl,int nents,unsigned int len,size_t recsize)571 unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
572 struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
573 {
574 BUG_ON(!nents);
575
576 len = __kfifo_max_r(len, recsize);
577
578 if (len + recsize > fifo->in - fifo->out)
579 return 0;
580
581 return setup_sgl(fifo, sgl, nents, len, fifo->out + recsize);
582 }
583 EXPORT_SYMBOL(__kfifo_dma_out_prepare_r);
584
__kfifo_dma_out_finish_r(struct __kfifo * fifo,size_t recsize)585 void __kfifo_dma_out_finish_r(struct __kfifo *fifo, size_t recsize)
586 {
587 unsigned int len;
588
589 len = __kfifo_peek_n(fifo, recsize);
590 fifo->out += len + recsize;
591 }
592 EXPORT_SYMBOL(__kfifo_dma_out_finish_r);
593
