scatterlist.h revision 345938 
1/*-
2 * Copyright (c) 2010 Isilon Systems, Inc.
3 * Copyright (c) 2010 iX Systems, Inc.
4 * Copyright (c) 2010 Panasas, Inc.
5 * Copyright (c) 2013-2017 Mellanox Technologies, Ltd.
6 * Copyright (c) 2015 Matthew Dillon <dillon@backplane.com>
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice unmodified, this list of conditions, and the following
14 *    disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 *
30 * $FreeBSD: stable/11/sys/compat/linuxkpi/common/include/linux/scatterlist.h 345938 2019-04-05 11:31:52Z hselasky $
31 */
32#ifndef	_LINUX_SCATTERLIST_H_
33#define	_LINUX_SCATTERLIST_H_
34
35#include <linux/page.h>
36#include <linux/slab.h>
37#include <linux/mm.h>
38
39struct scatterlist {
40	unsigned long page_link;
41#define	SG_PAGE_LINK_CHAIN	0x1UL
42#define	SG_PAGE_LINK_LAST	0x2UL
43#define	SG_PAGE_LINK_MASK	0x3UL
44	unsigned int offset;
45	unsigned int length;
46	dma_addr_t address;
47};
48
49CTASSERT((sizeof(struct scatterlist) & SG_PAGE_LINK_MASK) == 0);
50
51struct sg_table {
52	struct scatterlist *sgl;
53	unsigned int nents;
54	unsigned int orig_nents;
55};
56
57struct sg_page_iter {
58	struct scatterlist *sg;
59	unsigned int sg_pgoffset;
60	unsigned int maxents;
61	struct {
62		unsigned int nents;
63		int	pg_advance;
64	} internal;
65};
66
67#define	SCATTERLIST_MAX_SEGMENT	(-1U & ~(PAGE_SIZE - 1))
68
69#define	SG_MAX_SINGLE_ALLOC	(PAGE_SIZE / sizeof(struct scatterlist))
70
71#define	SG_MAGIC		0x87654321UL
72#define	SG_CHAIN		SG_PAGE_LINK_CHAIN
73#define	SG_END			SG_PAGE_LINK_LAST
74
75#define	sg_is_chain(sg)		((sg)->page_link & SG_PAGE_LINK_CHAIN)
76#define	sg_is_last(sg)		((sg)->page_link & SG_PAGE_LINK_LAST)
77#define	sg_chain_ptr(sg)	\
78	((struct scatterlist *) ((sg)->page_link & ~SG_PAGE_LINK_MASK))
79
80#define	sg_dma_address(sg)	(sg)->address
81#define	sg_dma_len(sg)		(sg)->length
82
83#define	for_each_sg_page(sgl, iter, nents, pgoffset)			\
84	for (_sg_iter_init(sgl, iter, nents, pgoffset);			\
85	     (iter)->sg; _sg_iter_next(iter))
86
87#define	for_each_sg(sglist, sg, sgmax, iter)				\
88	for (iter = 0, sg = (sglist); iter < (sgmax); iter++, sg = sg_next(sg))
89
90typedef struct scatterlist *(sg_alloc_fn) (unsigned int, gfp_t);
91typedef void (sg_free_fn) (struct scatterlist *, unsigned int);
92
93static inline void
94sg_assign_page(struct scatterlist *sg, struct page *page)
95{
96	unsigned long page_link = sg->page_link & SG_PAGE_LINK_MASK;
97
98	sg->page_link = page_link | (unsigned long)page;
99}
100
101static inline void
102sg_set_page(struct scatterlist *sg, struct page *page, unsigned int len,
103    unsigned int offset)
104{
105	sg_assign_page(sg, page);
106	sg->offset = offset;
107	sg->length = len;
108}
109
110static inline struct page *
111sg_page(struct scatterlist *sg)
112{
113	return ((struct page *)((sg)->page_link & ~SG_PAGE_LINK_MASK));
114}
115
116static inline void
117sg_set_buf(struct scatterlist *sg, const void *buf, unsigned int buflen)
118{
119	sg_set_page(sg, virt_to_page(buf), buflen,
120	    ((uintptr_t)buf) & (PAGE_SIZE - 1));
121}
122
123static inline struct scatterlist *
124sg_next(struct scatterlist *sg)
125{
126	if (sg_is_last(sg))
127		return (NULL);
128	sg++;
129	if (sg_is_chain(sg))
130		sg = sg_chain_ptr(sg);
131	return (sg);
132}
133
134static inline vm_paddr_t
135sg_phys(struct scatterlist *sg)
136{
137	return (VM_PAGE_TO_PHYS(sg_page(sg)) + sg->offset);
138}
139
140static inline void
141sg_chain(struct scatterlist *prv, unsigned int prv_nents,
142    struct scatterlist *sgl)
143{
144	struct scatterlist *sg = &prv[prv_nents - 1];
145
146	sg->offset = 0;
147	sg->length = 0;
148	sg->page_link = ((unsigned long)sgl |
149	    SG_PAGE_LINK_CHAIN) & ~SG_PAGE_LINK_LAST;
150}
151
152static inline void
153sg_mark_end(struct scatterlist *sg)
154{
155	sg->page_link |= SG_PAGE_LINK_LAST;
156	sg->page_link &= ~SG_PAGE_LINK_CHAIN;
157}
158
159static inline void
160sg_init_table(struct scatterlist *sg, unsigned int nents)
161{
162	bzero(sg, sizeof(*sg) * nents);
163	sg_mark_end(&sg[nents - 1]);
164}
165
166static struct scatterlist *
167sg_kmalloc(unsigned int nents, gfp_t gfp_mask)
168{
169	if (nents == SG_MAX_SINGLE_ALLOC) {
170		return ((void *)__get_free_page(gfp_mask));
171	} else
172		return (kmalloc(nents * sizeof(struct scatterlist), gfp_mask));
173}
174
175static inline void
176sg_kfree(struct scatterlist *sg, unsigned int nents)
177{
178	if (nents == SG_MAX_SINGLE_ALLOC) {
179		free_page((unsigned long)sg);
180	} else
181		kfree(sg);
182}
183
184static inline void
185__sg_free_table(struct sg_table *table, unsigned int max_ents,
186    bool skip_first_chunk, sg_free_fn * free_fn)
187{
188	struct scatterlist *sgl, *next;
189
190	if (unlikely(!table->sgl))
191		return;
192
193	sgl = table->sgl;
194	while (table->orig_nents) {
195		unsigned int alloc_size = table->orig_nents;
196		unsigned int sg_size;
197
198		if (alloc_size > max_ents) {
199			next = sg_chain_ptr(&sgl[max_ents - 1]);
200			alloc_size = max_ents;
201			sg_size = alloc_size - 1;
202		} else {
203			sg_size = alloc_size;
204			next = NULL;
205		}
206
207		table->orig_nents -= sg_size;
208		if (skip_first_chunk)
209			skip_first_chunk = 0;
210		else
211			free_fn(sgl, alloc_size);
212		sgl = next;
213	}
214
215	table->sgl = NULL;
216}
217
218static inline void
219sg_free_table(struct sg_table *table)
220{
221	__sg_free_table(table, SG_MAX_SINGLE_ALLOC, 0, sg_kfree);
222}
223
224static inline int
225__sg_alloc_table(struct sg_table *table, unsigned int nents,
226    unsigned int max_ents, struct scatterlist *first_chunk,
227    gfp_t gfp_mask, sg_alloc_fn *alloc_fn)
228{
229	struct scatterlist *sg, *prv;
230	unsigned int left;
231
232	memset(table, 0, sizeof(*table));
233
234	if (nents == 0)
235		return (-EINVAL);
236	left = nents;
237	prv = NULL;
238	do {
239		unsigned int sg_size;
240		unsigned int alloc_size = left;
241
242		if (alloc_size > max_ents) {
243			alloc_size = max_ents;
244			sg_size = alloc_size - 1;
245		} else
246			sg_size = alloc_size;
247
248		left -= sg_size;
249
250		if (first_chunk) {
251			sg = first_chunk;
252			first_chunk = NULL;
253		} else {
254			sg = alloc_fn(alloc_size, gfp_mask);
255		}
256		if (unlikely(!sg)) {
257			if (prv)
258				table->nents = ++table->orig_nents;
259
260			return (-ENOMEM);
261		}
262		sg_init_table(sg, alloc_size);
263		table->nents = table->orig_nents += sg_size;
264
265		if (prv)
266			sg_chain(prv, max_ents, sg);
267		else
268			table->sgl = sg;
269
270		if (!left)
271			sg_mark_end(&sg[sg_size - 1]);
272
273		prv = sg;
274	} while (left);
275
276	return (0);
277}
278
279static inline int
280sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
281{
282	int ret;
283
284	ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC,
285	    NULL, gfp_mask, sg_kmalloc);
286	if (unlikely(ret))
287		__sg_free_table(table, SG_MAX_SINGLE_ALLOC, 0, sg_kfree);
288
289	return (ret);
290}
291
292static inline int
293__sg_alloc_table_from_pages(struct sg_table *sgt,
294    struct page **pages, unsigned int count,
295    unsigned long off, unsigned long size,
296    unsigned int max_segment, gfp_t gfp_mask)
297{
298	unsigned int i, segs, cur, len;
299	int rc;
300	struct scatterlist *s;
301
302	if (__predict_false(!max_segment || offset_in_page(max_segment)))
303		return (-EINVAL);
304
305	len = 0;
306	for (segs = i = 1; i < count; ++i) {
307		len += PAGE_SIZE;
308		if (len >= max_segment ||
309		    page_to_pfn(pages[i]) != page_to_pfn(pages[i - 1]) + 1) {
310			++segs;
311			len = 0;
312		}
313	}
314	if (__predict_false((rc = sg_alloc_table(sgt, segs, gfp_mask))))
315		return (rc);
316
317	cur = 0;
318	for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
319		unsigned long seg_size;
320		unsigned int j;
321
322		len = 0;
323		for (j = cur + 1; j < count; ++j) {
324			len += PAGE_SIZE;
325			if (len >= max_segment || page_to_pfn(pages[j]) !=
326			    page_to_pfn(pages[j - 1]) + 1)
327				break;
328		}
329
330		seg_size = ((j - cur) << PAGE_SHIFT) - off;
331		sg_set_page(s, pages[cur], min(size, seg_size), off);
332		size -= seg_size;
333		off = 0;
334		cur = j;
335	}
336	return (0);
337}
338
339static inline int
340sg_alloc_table_from_pages(struct sg_table *sgt,
341    struct page **pages, unsigned int count,
342    unsigned long off, unsigned long size,
343    gfp_t gfp_mask)
344{
345
346	return (__sg_alloc_table_from_pages(sgt, pages, count, off, size,
347	    SCATTERLIST_MAX_SEGMENT, gfp_mask));
348}
349
350static inline int
351sg_nents(struct scatterlist *sg)
352{
353	int nents;
354
355	for (nents = 0; sg; sg = sg_next(sg))
356		nents++;
357	return (nents);
358}
359
360static inline void
361__sg_page_iter_start(struct sg_page_iter *piter,
362    struct scatterlist *sglist, unsigned int nents,
363    unsigned long pgoffset)
364{
365	piter->internal.pg_advance = 0;
366	piter->internal.nents = nents;
367
368	piter->sg = sglist;
369	piter->sg_pgoffset = pgoffset;
370}
371
372static inline void
373_sg_iter_next(struct sg_page_iter *iter)
374{
375	struct scatterlist *sg;
376	unsigned int pgcount;
377
378	sg = iter->sg;
379	pgcount = (sg->offset + sg->length + PAGE_SIZE - 1) >> PAGE_SHIFT;
380
381	++iter->sg_pgoffset;
382	while (iter->sg_pgoffset >= pgcount) {
383		iter->sg_pgoffset -= pgcount;
384		sg = sg_next(sg);
385		--iter->maxents;
386		if (sg == NULL || iter->maxents == 0)
387			break;
388		pgcount = (sg->offset + sg->length + PAGE_SIZE - 1) >> PAGE_SHIFT;
389	}
390	iter->sg = sg;
391}
392
393static inline int
394sg_page_count(struct scatterlist *sg)
395{
396	return (PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT);
397}
398
399static inline bool
400__sg_page_iter_next(struct sg_page_iter *piter)
401{
402	if (piter->internal.nents == 0)
403		return (0);
404	if (piter->sg == NULL)
405		return (0);
406
407	piter->sg_pgoffset += piter->internal.pg_advance;
408	piter->internal.pg_advance = 1;
409
410	while (piter->sg_pgoffset >= sg_page_count(piter->sg)) {
411		piter->sg_pgoffset -= sg_page_count(piter->sg);
412		piter->sg = sg_next(piter->sg);
413		if (--piter->internal.nents == 0)
414			return (0);
415		if (piter->sg == NULL)
416			return (0);
417	}
418	return (1);
419}
420
421static inline void
422_sg_iter_init(struct scatterlist *sgl, struct sg_page_iter *iter,
423    unsigned int nents, unsigned long pgoffset)
424{
425	if (nents) {
426		iter->sg = sgl;
427		iter->sg_pgoffset = pgoffset - 1;
428		iter->maxents = nents;
429		_sg_iter_next(iter);
430	} else {
431		iter->sg = NULL;
432		iter->sg_pgoffset = 0;
433		iter->maxents = 0;
434	}
435}
436
437static inline dma_addr_t
438sg_page_iter_dma_address(struct sg_page_iter *spi)
439{
440	return (spi->sg->address + (spi->sg_pgoffset << PAGE_SHIFT));
441}
442
443static inline struct page *
444sg_page_iter_page(struct sg_page_iter *piter)
445{
446	return (nth_page(sg_page(piter->sg), piter->sg_pgoffset));
447}
448
449
450#endif					/* _LINUX_SCATTERLIST_H_ */
451