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 storing 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