scatterlist.h revision 335413 
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 335413 2018-06-20 06:37:15Z 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
73#define	sg_is_chain(sg)		((sg)->page_link & SG_PAGE_LINK_CHAIN)
74#define	sg_is_last(sg)		((sg)->page_link & SG_PAGE_LINK_LAST)
75#define	sg_chain_ptr(sg)	\
76	((struct scatterlist *) ((sg)->page_link & ~SG_PAGE_LINK_MASK))
77
78#define	sg_dma_address(sg)	(sg)->address
79#define	sg_dma_len(sg)		(sg)->length
80
81#define	for_each_sg_page(sgl, iter, nents, pgoffset)			\
82	for (_sg_iter_init(sgl, iter, nents, pgoffset);			\
83	     (iter)->sg; _sg_iter_next(iter))
84
85#define	for_each_sg(sglist, sg, sgmax, iter)				\
86	for (iter = 0, sg = (sglist); iter < (sgmax); iter++, sg = sg_next(sg))
87
88typedef struct scatterlist *(sg_alloc_fn) (unsigned int, gfp_t);
89typedef void (sg_free_fn) (struct scatterlist *, unsigned int);
90
91static inline void
92sg_assign_page(struct scatterlist *sg, struct page *page)
93{
94	unsigned long page_link = sg->page_link & SG_PAGE_LINK_MASK;
95
96	sg->page_link = page_link | (unsigned long)page;
97}
98
99static inline void
100sg_set_page(struct scatterlist *sg, struct page *page, unsigned int len,
101    unsigned int offset)
102{
103	sg_assign_page(sg, page);
104	sg->offset = offset;
105	sg->length = len;
106}
107
108static inline struct page *
109sg_page(struct scatterlist *sg)
110{
111	return ((struct page *)((sg)->page_link & ~SG_PAGE_LINK_MASK));
112}
113
114static inline void
115sg_set_buf(struct scatterlist *sg, const void *buf, unsigned int buflen)
116{
117	sg_set_page(sg, virt_to_page(buf), buflen,
118	    ((uintptr_t)buf) & (PAGE_SIZE - 1));
119}
120
121static inline struct scatterlist *
122sg_next(struct scatterlist *sg)
123{
124	if (sg_is_last(sg))
125		return (NULL);
126	sg++;
127	if (sg_is_chain(sg))
128		sg = sg_chain_ptr(sg);
129	return (sg);
130}
131
132static inline vm_paddr_t
133sg_phys(struct scatterlist *sg)
134{
135	return (VM_PAGE_TO_PHYS(sg_page(sg)) + sg->offset);
136}
137
138static inline void
139sg_chain(struct scatterlist *prv, unsigned int prv_nents,
140    struct scatterlist *sgl)
141{
142	struct scatterlist *sg = &prv[prv_nents - 1];
143
144	sg->offset = 0;
145	sg->length = 0;
146	sg->page_link = ((unsigned long)sgl |
147	    SG_PAGE_LINK_CHAIN) & ~SG_PAGE_LINK_LAST;
148}
149
150static inline void
151sg_mark_end(struct scatterlist *sg)
152{
153	sg->page_link |= SG_PAGE_LINK_LAST;
154	sg->page_link &= ~SG_PAGE_LINK_CHAIN;
155}
156
157static inline void
158sg_init_table(struct scatterlist *sg, unsigned int nents)
159{
160	bzero(sg, sizeof(*sg) * nents);
161	sg_mark_end(&sg[nents - 1]);
162}
163
164static struct scatterlist *
165sg_kmalloc(unsigned int nents, gfp_t gfp_mask)
166{
167	if (nents == SG_MAX_SINGLE_ALLOC) {
168		return ((void *)__get_free_page(gfp_mask));
169	} else
170		return (kmalloc(nents * sizeof(struct scatterlist), gfp_mask));
171}
172
173static inline void
174sg_kfree(struct scatterlist *sg, unsigned int nents)
175{
176	if (nents == SG_MAX_SINGLE_ALLOC) {
177		free_page((unsigned long)sg);
178	} else
179		kfree(sg);
180}
181
182static inline void
183__sg_free_table(struct sg_table *table, unsigned int max_ents,
184    bool skip_first_chunk, sg_free_fn * free_fn)
185{
186	struct scatterlist *sgl, *next;
187
188	if (unlikely(!table->sgl))
189		return;
190
191	sgl = table->sgl;
192	while (table->orig_nents) {
193		unsigned int alloc_size = table->orig_nents;
194		unsigned int sg_size;
195
196		if (alloc_size > max_ents) {
197			next = sg_chain_ptr(&sgl[max_ents - 1]);
198			alloc_size = max_ents;
199			sg_size = alloc_size - 1;
200		} else {
201			sg_size = alloc_size;
202			next = NULL;
203		}
204
205		table->orig_nents -= sg_size;
206		if (skip_first_chunk)
207			skip_first_chunk = 0;
208		else
209			free_fn(sgl, alloc_size);
210		sgl = next;
211	}
212
213	table->sgl = NULL;
214}
215
216static inline void
217sg_free_table(struct sg_table *table)
218{
219	__sg_free_table(table, SG_MAX_SINGLE_ALLOC, 0, sg_kfree);
220}
221
222static inline int
223__sg_alloc_table(struct sg_table *table, unsigned int nents,
224    unsigned int max_ents, struct scatterlist *first_chunk,
225    gfp_t gfp_mask, sg_alloc_fn *alloc_fn)
226{
227	struct scatterlist *sg, *prv;
228	unsigned int left;
229
230	memset(table, 0, sizeof(*table));
231
232	if (nents == 0)
233		return (-EINVAL);
234	left = nents;
235	prv = NULL;
236	do {
237		unsigned int sg_size;
238		unsigned int alloc_size = left;
239
240		if (alloc_size > max_ents) {
241			alloc_size = max_ents;
242			sg_size = alloc_size - 1;
243		} else
244			sg_size = alloc_size;
245
246		left -= sg_size;
247
248		if (first_chunk) {
249			sg = first_chunk;
250			first_chunk = NULL;
251		} else {
252			sg = alloc_fn(alloc_size, gfp_mask);
253		}
254		if (unlikely(!sg)) {
255			if (prv)
256				table->nents = ++table->orig_nents;
257
258			return (-ENOMEM);
259		}
260		sg_init_table(sg, alloc_size);
261		table->nents = table->orig_nents += sg_size;
262
263		if (prv)
264			sg_chain(prv, max_ents, sg);
265		else
266			table->sgl = sg;
267
268		if (!left)
269			sg_mark_end(&sg[sg_size - 1]);
270
271		prv = sg;
272	} while (left);
273
274	return (0);
275}
276
277static inline int
278sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
279{
280	int ret;
281
282	ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC,
283	    NULL, gfp_mask, sg_kmalloc);
284	if (unlikely(ret))
285		__sg_free_table(table, SG_MAX_SINGLE_ALLOC, 0, sg_kfree);
286
287	return (ret);
288}
289
290static inline int
291__sg_alloc_table_from_pages(struct sg_table *sgt,
292    struct page **pages, unsigned int count,
293    unsigned long off, unsigned long size,
294    unsigned int max_segment, gfp_t gfp_mask)
295{
296	unsigned int i, segs, cur, len;
297	int rc;
298	struct scatterlist *s;
299
300	if (__predict_false(!max_segment || offset_in_page(max_segment)))
301		return (-EINVAL);
302
303	len = 0;
304	for (segs = i = 1; i < count; ++i) {
305		len += PAGE_SIZE;
306		if (len >= max_segment ||
307		    page_to_pfn(pages[i]) != page_to_pfn(pages[i - 1]) + 1) {
308			++segs;
309			len = 0;
310		}
311	}
312	if (__predict_false((rc = sg_alloc_table(sgt, segs, gfp_mask))))
313		return (rc);
314
315	cur = 0;
316	for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
317		unsigned long seg_size;
318		unsigned int j;
319
320		len = 0;
321		for (j = cur + 1; j < count; ++j) {
322			len += PAGE_SIZE;
323			if (len >= max_segment || page_to_pfn(pages[j]) !=
324			    page_to_pfn(pages[j - 1]) + 1)
325				break;
326		}
327
328		seg_size = ((j - cur) << PAGE_SHIFT) - off;
329		sg_set_page(s, pages[cur], min(size, seg_size), off);
330		size -= seg_size;
331		off = 0;
332		cur = j;
333	}
334	return (0);
335}
336
337static inline int
338sg_alloc_table_from_pages(struct sg_table *sgt,
339    struct page **pages, unsigned int count,
340    unsigned long off, unsigned long size,
341    gfp_t gfp_mask)
342{
343
344	return (__sg_alloc_table_from_pages(sgt, pages, count, off, size,
345	    SCATTERLIST_MAX_SEGMENT, gfp_mask));
346}
347
348static inline int
349sg_nents(struct scatterlist *sg)
350{
351	int nents;
352
353	for (nents = 0; sg; sg = sg_next(sg))
354		nents++;
355	return (nents);
356}
357
358static inline void
359__sg_page_iter_start(struct sg_page_iter *piter,
360    struct scatterlist *sglist, unsigned int nents,
361    unsigned long pgoffset)
362{
363	piter->internal.pg_advance = 0;
364	piter->internal.nents = nents;
365
366	piter->sg = sglist;
367	piter->sg_pgoffset = pgoffset;
368}
369
370static inline void
371_sg_iter_next(struct sg_page_iter *iter)
372{
373	struct scatterlist *sg;
374	unsigned int pgcount;
375
376	sg = iter->sg;
377	pgcount = (sg->offset + sg->length + PAGE_SIZE - 1) >> PAGE_SHIFT;
378
379	++iter->sg_pgoffset;
380	while (iter->sg_pgoffset >= pgcount) {
381		iter->sg_pgoffset -= pgcount;
382		sg = sg_next(sg);
383		--iter->maxents;
384		if (sg == NULL || iter->maxents == 0)
385			break;
386		pgcount = (sg->offset + sg->length + PAGE_SIZE - 1) >> PAGE_SHIFT;
387	}
388	iter->sg = sg;
389}
390
391static inline int
392sg_page_count(struct scatterlist *sg)
393{
394	return (PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT);
395}
396
397static inline bool
398__sg_page_iter_next(struct sg_page_iter *piter)
399{
400	if (piter->internal.nents == 0)
401		return (0);
402	if (piter->sg == NULL)
403		return (0);
404
405	piter->sg_pgoffset += piter->internal.pg_advance;
406	piter->internal.pg_advance = 1;
407
408	while (piter->sg_pgoffset >= sg_page_count(piter->sg)) {
409		piter->sg_pgoffset -= sg_page_count(piter->sg);
410		piter->sg = sg_next(piter->sg);
411		if (--piter->internal.nents == 0)
412			return (0);
413		if (piter->sg == NULL)
414			return (0);
415	}
416	return (1);
417}
418
419static inline void
420_sg_iter_init(struct scatterlist *sgl, struct sg_page_iter *iter,
421    unsigned int nents, unsigned long pgoffset)
422{
423	if (nents) {
424		iter->sg = sgl;
425		iter->sg_pgoffset = pgoffset - 1;
426		iter->maxents = nents;
427		_sg_iter_next(iter);
428	} else {
429		iter->sg = NULL;
430		iter->sg_pgoffset = 0;
431		iter->maxents = 0;
432	}
433}
434
435static inline dma_addr_t
436sg_page_iter_dma_address(struct sg_page_iter *spi)
437{
438	return (spi->sg->address + (spi->sg_pgoffset << PAGE_SHIFT));
439}
440
441static inline struct page *
442sg_page_iter_page(struct sg_page_iter *piter)
443{
444	return (nth_page(sg_page(piter->sg), piter->sg_pgoffset));
445}
446
447
448#endif					/* _LINUX_SCATTERLIST_H_ */
449