140b0b3f8SThomas Gleixner // SPDX-License-Identifier: GPL-2.0-only 20db9299fSJens Axboe /* 30db9299fSJens Axboe * Copyright (C) 2007 Jens Axboe <jens.axboe@oracle.com> 40db9299fSJens Axboe * 50db9299fSJens Axboe * Scatterlist handling helpers. 60db9299fSJens Axboe */ 78bc3bcc9SPaul Gortmaker #include <linux/export.h> 85a0e3ad6STejun Heo #include <linux/slab.h> 90db9299fSJens Axboe #include <linux/scatterlist.h> 10b1adaf65SFUJITA Tomonori #include <linux/highmem.h> 11b94de9bbSChris Wilson #include <linux/kmemleak.h> 120db9299fSJens Axboe 130db9299fSJens Axboe /** 140db9299fSJens Axboe * sg_next - return the next scatterlist entry in a list 150db9299fSJens Axboe * @sg: The current sg entry 160db9299fSJens Axboe * 170db9299fSJens Axboe * Description: 180db9299fSJens Axboe * Usually the next entry will be @sg@ + 1, but if this sg element is part 190db9299fSJens Axboe * of a chained scatterlist, it could jump to the start of a new 200db9299fSJens Axboe * scatterlist array. 210db9299fSJens Axboe * 220db9299fSJens Axboe **/ 230db9299fSJens Axboe struct scatterlist *sg_next(struct scatterlist *sg) 240db9299fSJens Axboe { 250db9299fSJens Axboe if (sg_is_last(sg)) 260db9299fSJens Axboe return NULL; 270db9299fSJens Axboe 280db9299fSJens Axboe sg++; 290db9299fSJens Axboe if (unlikely(sg_is_chain(sg))) 300db9299fSJens Axboe sg = sg_chain_ptr(sg); 310db9299fSJens Axboe 320db9299fSJens Axboe return sg; 330db9299fSJens Axboe } 340db9299fSJens Axboe EXPORT_SYMBOL(sg_next); 350db9299fSJens Axboe 360db9299fSJens Axboe /** 372e484610SMaxim Levitsky * sg_nents - return total count of entries in scatterlist 382e484610SMaxim Levitsky * @sg: The scatterlist 392e484610SMaxim Levitsky * 402e484610SMaxim Levitsky * Description: 412e484610SMaxim Levitsky * Allows to know how many entries are in sg, taking into acount 422e484610SMaxim Levitsky * chaining as well 432e484610SMaxim Levitsky * 442e484610SMaxim Levitsky **/ 452e484610SMaxim Levitsky int sg_nents(struct scatterlist *sg) 462e484610SMaxim Levitsky { 47232f1b51SMaxim Levitsky int nents; 48232f1b51SMaxim Levitsky for (nents = 0; sg; sg = sg_next(sg)) 492e484610SMaxim Levitsky nents++; 502e484610SMaxim Levitsky return nents; 512e484610SMaxim Levitsky } 522e484610SMaxim Levitsky EXPORT_SYMBOL(sg_nents); 532e484610SMaxim Levitsky 54cfaed10dSTom Lendacky /** 55cfaed10dSTom Lendacky * sg_nents_for_len - return total count of entries in scatterlist 56cfaed10dSTom Lendacky * needed to satisfy the supplied length 57cfaed10dSTom Lendacky * @sg: The scatterlist 58cfaed10dSTom Lendacky * @len: The total required length 59cfaed10dSTom Lendacky * 60cfaed10dSTom Lendacky * Description: 61cfaed10dSTom Lendacky * Determines the number of entries in sg that are required to meet 62cfaed10dSTom Lendacky * the supplied length, taking into acount chaining as well 63cfaed10dSTom Lendacky * 64cfaed10dSTom Lendacky * Returns: 65cfaed10dSTom Lendacky * the number of sg entries needed, negative error on failure 66cfaed10dSTom Lendacky * 67cfaed10dSTom Lendacky **/ 68cfaed10dSTom Lendacky int sg_nents_for_len(struct scatterlist *sg, u64 len) 69cfaed10dSTom Lendacky { 70cfaed10dSTom Lendacky int nents; 71cfaed10dSTom Lendacky u64 total; 72cfaed10dSTom Lendacky 73cfaed10dSTom Lendacky if (!len) 74cfaed10dSTom Lendacky return 0; 75cfaed10dSTom Lendacky 76cfaed10dSTom Lendacky for (nents = 0, total = 0; sg; sg = sg_next(sg)) { 77cfaed10dSTom Lendacky nents++; 78cfaed10dSTom Lendacky total += sg->length; 79cfaed10dSTom Lendacky if (total >= len) 80cfaed10dSTom Lendacky return nents; 81cfaed10dSTom Lendacky } 82cfaed10dSTom Lendacky 83cfaed10dSTom Lendacky return -EINVAL; 84cfaed10dSTom Lendacky } 85cfaed10dSTom Lendacky EXPORT_SYMBOL(sg_nents_for_len); 862e484610SMaxim Levitsky 872e484610SMaxim Levitsky /** 880db9299fSJens Axboe * sg_last - return the last scatterlist entry in a list 890db9299fSJens Axboe * @sgl: First entry in the scatterlist 900db9299fSJens Axboe * @nents: Number of entries in the scatterlist 910db9299fSJens Axboe * 920db9299fSJens Axboe * Description: 930db9299fSJens Axboe * Should only be used casually, it (currently) scans the entire list 940db9299fSJens Axboe * to get the last entry. 950db9299fSJens Axboe * 960db9299fSJens Axboe * Note that the @sgl@ pointer passed in need not be the first one, 970db9299fSJens Axboe * the important bit is that @nents@ denotes the number of entries that 980db9299fSJens Axboe * exist from @sgl@. 990db9299fSJens Axboe * 1000db9299fSJens Axboe **/ 1010db9299fSJens Axboe struct scatterlist *sg_last(struct scatterlist *sgl, unsigned int nents) 1020db9299fSJens Axboe { 1030db9299fSJens Axboe struct scatterlist *sg, *ret = NULL; 1040db9299fSJens Axboe unsigned int i; 1050db9299fSJens Axboe 1060db9299fSJens Axboe for_each_sg(sgl, sg, nents, i) 1070db9299fSJens Axboe ret = sg; 1080db9299fSJens Axboe 1090db9299fSJens Axboe BUG_ON(!sg_is_last(ret)); 1100db9299fSJens Axboe return ret; 1110db9299fSJens Axboe } 1120db9299fSJens Axboe EXPORT_SYMBOL(sg_last); 1130db9299fSJens Axboe 1140db9299fSJens Axboe /** 1150db9299fSJens Axboe * sg_init_table - Initialize SG table 1160db9299fSJens Axboe * @sgl: The SG table 1170db9299fSJens Axboe * @nents: Number of entries in table 1180db9299fSJens Axboe * 1190db9299fSJens Axboe * Notes: 1200db9299fSJens Axboe * If this is part of a chained sg table, sg_mark_end() should be 1210db9299fSJens Axboe * used only on the last table part. 1220db9299fSJens Axboe * 1230db9299fSJens Axboe **/ 1240db9299fSJens Axboe void sg_init_table(struct scatterlist *sgl, unsigned int nents) 1250db9299fSJens Axboe { 1260db9299fSJens Axboe memset(sgl, 0, sizeof(*sgl) * nents); 127f3851786SPrashant Bhole sg_init_marker(sgl, nents); 1280db9299fSJens Axboe } 1290db9299fSJens Axboe EXPORT_SYMBOL(sg_init_table); 1300db9299fSJens Axboe 1310db9299fSJens Axboe /** 1320db9299fSJens Axboe * sg_init_one - Initialize a single entry sg list 1330db9299fSJens Axboe * @sg: SG entry 1340db9299fSJens Axboe * @buf: Virtual address for IO 1350db9299fSJens Axboe * @buflen: IO length 1360db9299fSJens Axboe * 1370db9299fSJens Axboe **/ 1380db9299fSJens Axboe void sg_init_one(struct scatterlist *sg, const void *buf, unsigned int buflen) 1390db9299fSJens Axboe { 1400db9299fSJens Axboe sg_init_table(sg, 1); 1410db9299fSJens Axboe sg_set_buf(sg, buf, buflen); 1420db9299fSJens Axboe } 1430db9299fSJens Axboe EXPORT_SYMBOL(sg_init_one); 1440db9299fSJens Axboe 1450db9299fSJens Axboe /* 1460db9299fSJens Axboe * The default behaviour of sg_alloc_table() is to use these kmalloc/kfree 1470db9299fSJens Axboe * helpers. 1480db9299fSJens Axboe */ 1490db9299fSJens Axboe static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask) 1500db9299fSJens Axboe { 151b94de9bbSChris Wilson if (nents == SG_MAX_SINGLE_ALLOC) { 152b94de9bbSChris Wilson /* 153b94de9bbSChris Wilson * Kmemleak doesn't track page allocations as they are not 154b94de9bbSChris Wilson * commonly used (in a raw form) for kernel data structures. 155b94de9bbSChris Wilson * As we chain together a list of pages and then a normal 156b94de9bbSChris Wilson * kmalloc (tracked by kmemleak), in order to for that last 157b94de9bbSChris Wilson * allocation not to become decoupled (and thus a 158b94de9bbSChris Wilson * false-positive) we need to inform kmemleak of all the 159b94de9bbSChris Wilson * intermediate allocations. 160b94de9bbSChris Wilson */ 161b94de9bbSChris Wilson void *ptr = (void *) __get_free_page(gfp_mask); 162b94de9bbSChris Wilson kmemleak_alloc(ptr, PAGE_SIZE, 1, gfp_mask); 163b94de9bbSChris Wilson return ptr; 164b94de9bbSChris Wilson } else 1656da2ec56SKees Cook return kmalloc_array(nents, sizeof(struct scatterlist), 1666da2ec56SKees Cook gfp_mask); 1670db9299fSJens Axboe } 1680db9299fSJens Axboe 1690db9299fSJens Axboe static void sg_kfree(struct scatterlist *sg, unsigned int nents) 1700db9299fSJens Axboe { 171b94de9bbSChris Wilson if (nents == SG_MAX_SINGLE_ALLOC) { 172b94de9bbSChris Wilson kmemleak_free(sg); 1730db9299fSJens Axboe free_page((unsigned long) sg); 174b94de9bbSChris Wilson } else 1750db9299fSJens Axboe kfree(sg); 1760db9299fSJens Axboe } 1770db9299fSJens Axboe 1780db9299fSJens Axboe /** 1790db9299fSJens Axboe * __sg_free_table - Free a previously mapped sg table 1800db9299fSJens Axboe * @table: The sg table header to use 1817cedb1f1SJames Bottomley * @max_ents: The maximum number of entries per single scatterlist 1824635873cSMing Lei * @nents_first_chunk: Number of entries int the (preallocated) first 1834635873cSMing Lei * scatterlist chunk, 0 means no such preallocated first chunk 1840db9299fSJens Axboe * @free_fn: Free function 1850db9299fSJens Axboe * 1860db9299fSJens Axboe * Description: 1877cedb1f1SJames Bottomley * Free an sg table previously allocated and setup with 1887cedb1f1SJames Bottomley * __sg_alloc_table(). The @max_ents value must be identical to 1897cedb1f1SJames Bottomley * that previously used with __sg_alloc_table(). 1900db9299fSJens Axboe * 1910db9299fSJens Axboe **/ 1927cedb1f1SJames Bottomley void __sg_free_table(struct sg_table *table, unsigned int max_ents, 1934635873cSMing Lei unsigned int nents_first_chunk, sg_free_fn *free_fn) 1940db9299fSJens Axboe { 1950db9299fSJens Axboe struct scatterlist *sgl, *next; 1964635873cSMing Lei unsigned curr_max_ents = nents_first_chunk ?: max_ents; 1970db9299fSJens Axboe 1980db9299fSJens Axboe if (unlikely(!table->sgl)) 1990db9299fSJens Axboe return; 2000db9299fSJens Axboe 2010db9299fSJens Axboe sgl = table->sgl; 2020db9299fSJens Axboe while (table->orig_nents) { 2030db9299fSJens Axboe unsigned int alloc_size = table->orig_nents; 2040db9299fSJens Axboe unsigned int sg_size; 2050db9299fSJens Axboe 2060db9299fSJens Axboe /* 2077cedb1f1SJames Bottomley * If we have more than max_ents segments left, 2080db9299fSJens Axboe * then assign 'next' to the sg table after the current one. 2090db9299fSJens Axboe * sg_size is then one less than alloc size, since the last 2100db9299fSJens Axboe * element is the chain pointer. 2110db9299fSJens Axboe */ 2124635873cSMing Lei if (alloc_size > curr_max_ents) { 2134635873cSMing Lei next = sg_chain_ptr(&sgl[curr_max_ents - 1]); 2144635873cSMing Lei alloc_size = curr_max_ents; 2150db9299fSJens Axboe sg_size = alloc_size - 1; 2160db9299fSJens Axboe } else { 2170db9299fSJens Axboe sg_size = alloc_size; 2180db9299fSJens Axboe next = NULL; 2190db9299fSJens Axboe } 2200db9299fSJens Axboe 2210db9299fSJens Axboe table->orig_nents -= sg_size; 2224635873cSMing Lei if (nents_first_chunk) 2234635873cSMing Lei nents_first_chunk = 0; 224c21e59d8STony Battersby else 225c21e59d8STony Battersby free_fn(sgl, alloc_size); 2260db9299fSJens Axboe sgl = next; 2274635873cSMing Lei curr_max_ents = max_ents; 2280db9299fSJens Axboe } 2290db9299fSJens Axboe 2300db9299fSJens Axboe table->sgl = NULL; 2310db9299fSJens Axboe } 2320db9299fSJens Axboe EXPORT_SYMBOL(__sg_free_table); 2330db9299fSJens Axboe 2340db9299fSJens Axboe /** 2350db9299fSJens Axboe * sg_free_table - Free a previously allocated sg table 2360db9299fSJens Axboe * @table: The mapped sg table header 2370db9299fSJens Axboe * 2380db9299fSJens Axboe **/ 2390db9299fSJens Axboe void sg_free_table(struct sg_table *table) 2400db9299fSJens Axboe { 241c53c6d6aSChristoph Hellwig __sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree); 2420db9299fSJens Axboe } 2430db9299fSJens Axboe EXPORT_SYMBOL(sg_free_table); 2440db9299fSJens Axboe 2450db9299fSJens Axboe /** 2460db9299fSJens Axboe * __sg_alloc_table - Allocate and initialize an sg table with given allocator 2470db9299fSJens Axboe * @table: The sg table header to use 2480db9299fSJens Axboe * @nents: Number of entries in sg list 2497cedb1f1SJames Bottomley * @max_ents: The maximum number of entries the allocator returns per call 2504635873cSMing Lei * @nents_first_chunk: Number of entries int the (preallocated) first 2514635873cSMing Lei * scatterlist chunk, 0 means no such preallocated chunk provided by user 2520db9299fSJens Axboe * @gfp_mask: GFP allocation mask 2530db9299fSJens Axboe * @alloc_fn: Allocator to use 2540db9299fSJens Axboe * 2557cedb1f1SJames Bottomley * Description: 2567cedb1f1SJames Bottomley * This function returns a @table @nents long. The allocator is 2577cedb1f1SJames Bottomley * defined to return scatterlist chunks of maximum size @max_ents. 2587cedb1f1SJames Bottomley * Thus if @nents is bigger than @max_ents, the scatterlists will be 2597cedb1f1SJames Bottomley * chained in units of @max_ents. 2607cedb1f1SJames Bottomley * 2610db9299fSJens Axboe * Notes: 2620db9299fSJens Axboe * If this function returns non-0 (eg failure), the caller must call 2630db9299fSJens Axboe * __sg_free_table() to cleanup any leftover allocations. 2640db9299fSJens Axboe * 2650db9299fSJens Axboe **/ 2667cedb1f1SJames Bottomley int __sg_alloc_table(struct sg_table *table, unsigned int nents, 267c53c6d6aSChristoph Hellwig unsigned int max_ents, struct scatterlist *first_chunk, 2684635873cSMing Lei unsigned int nents_first_chunk, gfp_t gfp_mask, 2694635873cSMing Lei sg_alloc_fn *alloc_fn) 2700db9299fSJens Axboe { 2710db9299fSJens Axboe struct scatterlist *sg, *prv; 2720db9299fSJens Axboe unsigned int left; 2734635873cSMing Lei unsigned curr_max_ents = nents_first_chunk ?: max_ents; 2744635873cSMing Lei unsigned prv_max_ents; 2750db9299fSJens Axboe 27627daabd9SDan Carpenter memset(table, 0, sizeof(*table)); 27727daabd9SDan Carpenter 27827daabd9SDan Carpenter if (nents == 0) 27927daabd9SDan Carpenter return -EINVAL; 2807c703e54SChristoph Hellwig #ifdef CONFIG_ARCH_NO_SG_CHAIN 2816fd59a83SNick Bowler if (WARN_ON_ONCE(nents > max_ents)) 2826fd59a83SNick Bowler return -EINVAL; 2830db9299fSJens Axboe #endif 2840db9299fSJens Axboe 2850db9299fSJens Axboe left = nents; 2860db9299fSJens Axboe prv = NULL; 2870db9299fSJens Axboe do { 2880db9299fSJens Axboe unsigned int sg_size, alloc_size = left; 2890db9299fSJens Axboe 2904635873cSMing Lei if (alloc_size > curr_max_ents) { 2914635873cSMing Lei alloc_size = curr_max_ents; 2920db9299fSJens Axboe sg_size = alloc_size - 1; 2930db9299fSJens Axboe } else 2940db9299fSJens Axboe sg_size = alloc_size; 2950db9299fSJens Axboe 2960db9299fSJens Axboe left -= sg_size; 2970db9299fSJens Axboe 298c53c6d6aSChristoph Hellwig if (first_chunk) { 299c53c6d6aSChristoph Hellwig sg = first_chunk; 300c53c6d6aSChristoph Hellwig first_chunk = NULL; 301c53c6d6aSChristoph Hellwig } else { 3020db9299fSJens Axboe sg = alloc_fn(alloc_size, gfp_mask); 303c53c6d6aSChristoph Hellwig } 304edce6820SJeffrey Carlyle if (unlikely(!sg)) { 305edce6820SJeffrey Carlyle /* 306edce6820SJeffrey Carlyle * Adjust entry count to reflect that the last 307edce6820SJeffrey Carlyle * entry of the previous table won't be used for 308edce6820SJeffrey Carlyle * linkage. Without this, sg_kfree() may get 309edce6820SJeffrey Carlyle * confused. 310edce6820SJeffrey Carlyle */ 311edce6820SJeffrey Carlyle if (prv) 312edce6820SJeffrey Carlyle table->nents = ++table->orig_nents; 313edce6820SJeffrey Carlyle 3140db9299fSJens Axboe return -ENOMEM; 315edce6820SJeffrey Carlyle } 3160db9299fSJens Axboe 3170db9299fSJens Axboe sg_init_table(sg, alloc_size); 3180db9299fSJens Axboe table->nents = table->orig_nents += sg_size; 3190db9299fSJens Axboe 3200db9299fSJens Axboe /* 3210db9299fSJens Axboe * If this is the first mapping, assign the sg table header. 3220db9299fSJens Axboe * If this is not the first mapping, chain previous part. 3230db9299fSJens Axboe */ 3240db9299fSJens Axboe if (prv) 3254635873cSMing Lei sg_chain(prv, prv_max_ents, sg); 3260db9299fSJens Axboe else 3270db9299fSJens Axboe table->sgl = sg; 3280db9299fSJens Axboe 3290db9299fSJens Axboe /* 3300db9299fSJens Axboe * If no more entries after this one, mark the end 3310db9299fSJens Axboe */ 3320db9299fSJens Axboe if (!left) 3330db9299fSJens Axboe sg_mark_end(&sg[sg_size - 1]); 3340db9299fSJens Axboe 3350db9299fSJens Axboe prv = sg; 3364635873cSMing Lei prv_max_ents = curr_max_ents; 3374635873cSMing Lei curr_max_ents = max_ents; 3380db9299fSJens Axboe } while (left); 3390db9299fSJens Axboe 3400db9299fSJens Axboe return 0; 3410db9299fSJens Axboe } 3420db9299fSJens Axboe EXPORT_SYMBOL(__sg_alloc_table); 3430db9299fSJens Axboe 3440db9299fSJens Axboe /** 3450db9299fSJens Axboe * sg_alloc_table - Allocate and initialize an sg table 3460db9299fSJens Axboe * @table: The sg table header to use 3470db9299fSJens Axboe * @nents: Number of entries in sg list 3480db9299fSJens Axboe * @gfp_mask: GFP allocation mask 3490db9299fSJens Axboe * 3500db9299fSJens Axboe * Description: 3510db9299fSJens Axboe * Allocate and initialize an sg table. If @nents@ is larger than 3520db9299fSJens Axboe * SG_MAX_SINGLE_ALLOC a chained sg table will be setup. 3530db9299fSJens Axboe * 3540db9299fSJens Axboe **/ 3550db9299fSJens Axboe int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask) 3560db9299fSJens Axboe { 3570db9299fSJens Axboe int ret; 3580db9299fSJens Axboe 3597cedb1f1SJames Bottomley ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC, 3604635873cSMing Lei NULL, 0, gfp_mask, sg_kmalloc); 3610db9299fSJens Axboe if (unlikely(ret)) 3624635873cSMing Lei __sg_free_table(table, SG_MAX_SINGLE_ALLOC, 0, sg_kfree); 3630db9299fSJens Axboe 3640db9299fSJens Axboe return ret; 3650db9299fSJens Axboe } 3660db9299fSJens Axboe EXPORT_SYMBOL(sg_alloc_table); 367b1adaf65SFUJITA Tomonori 36807da1223SMaor Gottlieb static struct scatterlist *get_next_sg(struct sg_table *table, 36907da1223SMaor Gottlieb struct scatterlist *cur, 37007da1223SMaor Gottlieb unsigned long needed_sges, 37107da1223SMaor Gottlieb gfp_t gfp_mask) 37207da1223SMaor Gottlieb { 37307da1223SMaor Gottlieb struct scatterlist *new_sg, *next_sg; 37407da1223SMaor Gottlieb unsigned int alloc_size; 37507da1223SMaor Gottlieb 37607da1223SMaor Gottlieb if (cur) { 37707da1223SMaor Gottlieb next_sg = sg_next(cur); 37807da1223SMaor Gottlieb /* Check if last entry should be keeped for chainning */ 37907da1223SMaor Gottlieb if (!sg_is_last(next_sg) || needed_sges == 1) 38007da1223SMaor Gottlieb return next_sg; 38107da1223SMaor Gottlieb } 38207da1223SMaor Gottlieb 38307da1223SMaor Gottlieb alloc_size = min_t(unsigned long, needed_sges, SG_MAX_SINGLE_ALLOC); 38407da1223SMaor Gottlieb new_sg = sg_kmalloc(alloc_size, gfp_mask); 38507da1223SMaor Gottlieb if (!new_sg) 38607da1223SMaor Gottlieb return ERR_PTR(-ENOMEM); 38707da1223SMaor Gottlieb sg_init_table(new_sg, alloc_size); 38807da1223SMaor Gottlieb if (cur) { 38907da1223SMaor Gottlieb __sg_chain(next_sg, new_sg); 39007da1223SMaor Gottlieb table->orig_nents += alloc_size - 1; 39107da1223SMaor Gottlieb } else { 39207da1223SMaor Gottlieb table->sgl = new_sg; 39307da1223SMaor Gottlieb table->orig_nents = alloc_size; 39407da1223SMaor Gottlieb table->nents = 0; 39507da1223SMaor Gottlieb } 39607da1223SMaor Gottlieb return new_sg; 39707da1223SMaor Gottlieb } 39807da1223SMaor Gottlieb 399b1adaf65SFUJITA Tomonori /** 40089d8589cSTvrtko Ursulin * __sg_alloc_table_from_pages - Allocate and initialize an sg table from 401efc42bc9STomasz Stanislawski * an array of pages 402efc42bc9STomasz Stanislawski * @sgt: The sg table header to use 403efc42bc9STomasz Stanislawski * @pages: Pointer to an array of page pointers 404efc42bc9STomasz Stanislawski * @n_pages: Number of pages in the pages array 405efc42bc9STomasz Stanislawski * @offset: Offset from start of the first page to the start of a buffer 406efc42bc9STomasz Stanislawski * @size: Number of valid bytes in the buffer (after offset) 4079a40401cSJason Gunthorpe * @max_segment: Maximum size of a scatterlist element in bytes 40807da1223SMaor Gottlieb * @prv: Last populated sge in sgt 40907da1223SMaor Gottlieb * @left_pages: Left pages caller have to set after this call 410efc42bc9STomasz Stanislawski * @gfp_mask: GFP allocation mask 411efc42bc9STomasz Stanislawski * 412efc42bc9STomasz Stanislawski * Description: 41307da1223SMaor Gottlieb * If @prv is NULL, allocate and initialize an sg table from a list of pages, 41407da1223SMaor Gottlieb * else reuse the scatterlist passed in at @prv. 41507da1223SMaor Gottlieb * Contiguous ranges of the pages are squashed into a single scatterlist 41607da1223SMaor Gottlieb * entry up to the maximum size specified in @max_segment. A user may 41707da1223SMaor Gottlieb * provide an offset at a start and a size of valid data in a buffer 41807da1223SMaor Gottlieb * specified by the page array. 419efc42bc9STomasz Stanislawski * 420efc42bc9STomasz Stanislawski * Returns: 42107da1223SMaor Gottlieb * Last SGE in sgt on success, PTR_ERR on otherwise. 42207da1223SMaor Gottlieb * The allocation in @sgt must be released by sg_free_table. 42307da1223SMaor Gottlieb * 42407da1223SMaor Gottlieb * Notes: 42507da1223SMaor Gottlieb * If this function returns non-0 (eg failure), the caller must call 42607da1223SMaor Gottlieb * sg_free_table() to cleanup any leftover allocations. 427efc42bc9STomasz Stanislawski */ 42807da1223SMaor Gottlieb struct scatterlist *__sg_alloc_table_from_pages(struct sg_table *sgt, 42907da1223SMaor Gottlieb struct page **pages, unsigned int n_pages, unsigned int offset, 43089d8589cSTvrtko Ursulin unsigned long size, unsigned int max_segment, 43107da1223SMaor Gottlieb struct scatterlist *prv, unsigned int left_pages, 432efc42bc9STomasz Stanislawski gfp_t gfp_mask) 433efc42bc9STomasz Stanislawski { 43407da1223SMaor Gottlieb unsigned int chunks, cur_page, seg_len, i, prv_len = 0; 43507da1223SMaor Gottlieb unsigned int added_nents = 0; 43607da1223SMaor Gottlieb struct scatterlist *s = prv; 437efc42bc9STomasz Stanislawski 4389a40401cSJason Gunthorpe /* 4399a40401cSJason Gunthorpe * The algorithm below requires max_segment to be aligned to PAGE_SIZE 4409a40401cSJason Gunthorpe * otherwise it can overshoot. 4419a40401cSJason Gunthorpe */ 4429a40401cSJason Gunthorpe max_segment = ALIGN_DOWN(max_segment, PAGE_SIZE); 4439a40401cSJason Gunthorpe if (WARN_ON(max_segment < PAGE_SIZE)) 44407da1223SMaor Gottlieb return ERR_PTR(-EINVAL); 44507da1223SMaor Gottlieb 44607da1223SMaor Gottlieb if (IS_ENABLED(CONFIG_ARCH_NO_SG_CHAIN) && prv) 44707da1223SMaor Gottlieb return ERR_PTR(-EOPNOTSUPP); 44807da1223SMaor Gottlieb 44907da1223SMaor Gottlieb if (prv) { 45007da1223SMaor Gottlieb unsigned long paddr = (page_to_pfn(sg_page(prv)) * PAGE_SIZE + 45107da1223SMaor Gottlieb prv->offset + prv->length) / 45207da1223SMaor Gottlieb PAGE_SIZE; 45307da1223SMaor Gottlieb 45407da1223SMaor Gottlieb if (WARN_ON(offset)) 45507da1223SMaor Gottlieb return ERR_PTR(-EINVAL); 45607da1223SMaor Gottlieb 45707da1223SMaor Gottlieb /* Merge contiguous pages into the last SG */ 45807da1223SMaor Gottlieb prv_len = prv->length; 45907da1223SMaor Gottlieb while (n_pages && page_to_pfn(pages[0]) == paddr) { 46007da1223SMaor Gottlieb if (prv->length + PAGE_SIZE > max_segment) 46107da1223SMaor Gottlieb break; 46207da1223SMaor Gottlieb prv->length += PAGE_SIZE; 46307da1223SMaor Gottlieb paddr++; 46407da1223SMaor Gottlieb pages++; 46507da1223SMaor Gottlieb n_pages--; 46607da1223SMaor Gottlieb } 46707da1223SMaor Gottlieb if (!n_pages) 46807da1223SMaor Gottlieb goto out; 46907da1223SMaor Gottlieb } 47089d8589cSTvrtko Ursulin 471efc42bc9STomasz Stanislawski /* compute number of contiguous chunks */ 472efc42bc9STomasz Stanislawski chunks = 1; 473c125906bSTvrtko Ursulin seg_len = 0; 474c125906bSTvrtko Ursulin for (i = 1; i < n_pages; i++) { 475c125906bSTvrtko Ursulin seg_len += PAGE_SIZE; 476c125906bSTvrtko Ursulin if (seg_len >= max_segment || 477c125906bSTvrtko Ursulin page_to_pfn(pages[i]) != page_to_pfn(pages[i - 1]) + 1) { 478c125906bSTvrtko Ursulin chunks++; 479c125906bSTvrtko Ursulin seg_len = 0; 480c125906bSTvrtko Ursulin } 481c125906bSTvrtko Ursulin } 482efc42bc9STomasz Stanislawski 483efc42bc9STomasz Stanislawski /* merging chunks and putting them into the scatterlist */ 484efc42bc9STomasz Stanislawski cur_page = 0; 48507da1223SMaor Gottlieb for (i = 0; i < chunks; i++) { 486c125906bSTvrtko Ursulin unsigned int j, chunk_size; 487efc42bc9STomasz Stanislawski 488efc42bc9STomasz Stanislawski /* look for the end of the current chunk */ 489c125906bSTvrtko Ursulin seg_len = 0; 490c125906bSTvrtko Ursulin for (j = cur_page + 1; j < n_pages; j++) { 491c125906bSTvrtko Ursulin seg_len += PAGE_SIZE; 492c125906bSTvrtko Ursulin if (seg_len >= max_segment || 493c125906bSTvrtko Ursulin page_to_pfn(pages[j]) != 494efc42bc9STomasz Stanislawski page_to_pfn(pages[j - 1]) + 1) 495efc42bc9STomasz Stanislawski break; 496c125906bSTvrtko Ursulin } 497efc42bc9STomasz Stanislawski 49807da1223SMaor Gottlieb /* Pass how many chunks might be left */ 49907da1223SMaor Gottlieb s = get_next_sg(sgt, s, chunks - i + left_pages, gfp_mask); 50007da1223SMaor Gottlieb if (IS_ERR(s)) { 50107da1223SMaor Gottlieb /* 50207da1223SMaor Gottlieb * Adjust entry length to be as before function was 50307da1223SMaor Gottlieb * called. 50407da1223SMaor Gottlieb */ 50507da1223SMaor Gottlieb if (prv) 50607da1223SMaor Gottlieb prv->length = prv_len; 50707da1223SMaor Gottlieb return s; 50807da1223SMaor Gottlieb } 509efc42bc9STomasz Stanislawski chunk_size = ((j - cur_page) << PAGE_SHIFT) - offset; 510c125906bSTvrtko Ursulin sg_set_page(s, pages[cur_page], 511c125906bSTvrtko Ursulin min_t(unsigned long, size, chunk_size), offset); 51207da1223SMaor Gottlieb added_nents++; 513efc42bc9STomasz Stanislawski size -= chunk_size; 514efc42bc9STomasz Stanislawski offset = 0; 515efc42bc9STomasz Stanislawski cur_page = j; 516efc42bc9STomasz Stanislawski } 51707da1223SMaor Gottlieb sgt->nents += added_nents; 51807da1223SMaor Gottlieb out: 51907da1223SMaor Gottlieb if (!left_pages) 52007da1223SMaor Gottlieb sg_mark_end(s); 52107da1223SMaor Gottlieb return s; 522efc42bc9STomasz Stanislawski } 52389d8589cSTvrtko Ursulin EXPORT_SYMBOL(__sg_alloc_table_from_pages); 52489d8589cSTvrtko Ursulin 52589d8589cSTvrtko Ursulin /** 52689d8589cSTvrtko Ursulin * sg_alloc_table_from_pages - Allocate and initialize an sg table from 52789d8589cSTvrtko Ursulin * an array of pages 52889d8589cSTvrtko Ursulin * @sgt: The sg table header to use 52989d8589cSTvrtko Ursulin * @pages: Pointer to an array of page pointers 53089d8589cSTvrtko Ursulin * @n_pages: Number of pages in the pages array 53189d8589cSTvrtko Ursulin * @offset: Offset from start of the first page to the start of a buffer 53289d8589cSTvrtko Ursulin * @size: Number of valid bytes in the buffer (after offset) 53389d8589cSTvrtko Ursulin * @gfp_mask: GFP allocation mask 53489d8589cSTvrtko Ursulin * 53589d8589cSTvrtko Ursulin * Description: 53689d8589cSTvrtko Ursulin * Allocate and initialize an sg table from a list of pages. Contiguous 53789d8589cSTvrtko Ursulin * ranges of the pages are squashed into a single scatterlist node. A user 53889d8589cSTvrtko Ursulin * may provide an offset at a start and a size of valid data in a buffer 53989d8589cSTvrtko Ursulin * specified by the page array. The returned sg table is released by 54089d8589cSTvrtko Ursulin * sg_free_table. 54189d8589cSTvrtko Ursulin * 54289d8589cSTvrtko Ursulin * Returns: 54389d8589cSTvrtko Ursulin * 0 on success, negative error on failure 54489d8589cSTvrtko Ursulin */ 54589d8589cSTvrtko Ursulin int sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages, 54689d8589cSTvrtko Ursulin unsigned int n_pages, unsigned int offset, 54789d8589cSTvrtko Ursulin unsigned long size, gfp_t gfp_mask) 54889d8589cSTvrtko Ursulin { 54907da1223SMaor Gottlieb return PTR_ERR_OR_ZERO(__sg_alloc_table_from_pages(sgt, pages, n_pages, 5509a40401cSJason Gunthorpe offset, size, UINT_MAX, NULL, 0, gfp_mask)); 55189d8589cSTvrtko Ursulin } 552efc42bc9STomasz Stanislawski EXPORT_SYMBOL(sg_alloc_table_from_pages); 553efc42bc9STomasz Stanislawski 554e80a0af4SBart Van Assche #ifdef CONFIG_SGL_ALLOC 555e80a0af4SBart Van Assche 556e80a0af4SBart Van Assche /** 557e80a0af4SBart Van Assche * sgl_alloc_order - allocate a scatterlist and its pages 558e80a0af4SBart Van Assche * @length: Length in bytes of the scatterlist. Must be at least one 559e80a0af4SBart Van Assche * @order: Second argument for alloc_pages() 560e80a0af4SBart Van Assche * @chainable: Whether or not to allocate an extra element in the scatterlist 561e80a0af4SBart Van Assche * for scatterlist chaining purposes 562e80a0af4SBart Van Assche * @gfp: Memory allocation flags 563e80a0af4SBart Van Assche * @nent_p: [out] Number of entries in the scatterlist that have pages 564e80a0af4SBart Van Assche * 565e80a0af4SBart Van Assche * Returns: A pointer to an initialized scatterlist or %NULL upon failure. 566e80a0af4SBart Van Assche */ 567e80a0af4SBart Van Assche struct scatterlist *sgl_alloc_order(unsigned long long length, 568e80a0af4SBart Van Assche unsigned int order, bool chainable, 569e80a0af4SBart Van Assche gfp_t gfp, unsigned int *nent_p) 570e80a0af4SBart Van Assche { 571e80a0af4SBart Van Assche struct scatterlist *sgl, *sg; 572e80a0af4SBart Van Assche struct page *page; 573e80a0af4SBart Van Assche unsigned int nent, nalloc; 574e80a0af4SBart Van Assche u32 elem_len; 575e80a0af4SBart Van Assche 576e80a0af4SBart Van Assche nent = round_up(length, PAGE_SIZE << order) >> (PAGE_SHIFT + order); 577e80a0af4SBart Van Assche /* Check for integer overflow */ 578e80a0af4SBart Van Assche if (length > (nent << (PAGE_SHIFT + order))) 579e80a0af4SBart Van Assche return NULL; 580e80a0af4SBart Van Assche nalloc = nent; 581e80a0af4SBart Van Assche if (chainable) { 582e80a0af4SBart Van Assche /* Check for integer overflow */ 583e80a0af4SBart Van Assche if (nalloc + 1 < nalloc) 584e80a0af4SBart Van Assche return NULL; 585e80a0af4SBart Van Assche nalloc++; 586e80a0af4SBart Van Assche } 587e80a0af4SBart Van Assche sgl = kmalloc_array(nalloc, sizeof(struct scatterlist), 5886ed9b92eSChristophe JAILLET gfp & ~GFP_DMA); 589e80a0af4SBart Van Assche if (!sgl) 590e80a0af4SBart Van Assche return NULL; 591e80a0af4SBart Van Assche 5928c7a8d1cSBart Van Assche sg_init_table(sgl, nalloc); 593e80a0af4SBart Van Assche sg = sgl; 594e80a0af4SBart Van Assche while (length) { 595e80a0af4SBart Van Assche elem_len = min_t(u64, length, PAGE_SIZE << order); 596e80a0af4SBart Van Assche page = alloc_pages(gfp, order); 597e80a0af4SBart Van Assche if (!page) { 598b2a182a4SDouglas Gilbert sgl_free_order(sgl, order); 599e80a0af4SBart Van Assche return NULL; 600e80a0af4SBart Van Assche } 601e80a0af4SBart Van Assche 602e80a0af4SBart Van Assche sg_set_page(sg, page, elem_len, 0); 603e80a0af4SBart Van Assche length -= elem_len; 604e80a0af4SBart Van Assche sg = sg_next(sg); 605e80a0af4SBart Van Assche } 6068c7a8d1cSBart Van Assche WARN_ONCE(length, "length = %lld\n", length); 607e80a0af4SBart Van Assche if (nent_p) 608e80a0af4SBart Van Assche *nent_p = nent; 609e80a0af4SBart Van Assche return sgl; 610e80a0af4SBart Van Assche } 611e80a0af4SBart Van Assche EXPORT_SYMBOL(sgl_alloc_order); 612e80a0af4SBart Van Assche 613e80a0af4SBart Van Assche /** 614e80a0af4SBart Van Assche * sgl_alloc - allocate a scatterlist and its pages 615e80a0af4SBart Van Assche * @length: Length in bytes of the scatterlist 616e80a0af4SBart Van Assche * @gfp: Memory allocation flags 617e80a0af4SBart Van Assche * @nent_p: [out] Number of entries in the scatterlist 618e80a0af4SBart Van Assche * 619e80a0af4SBart Van Assche * Returns: A pointer to an initialized scatterlist or %NULL upon failure. 620e80a0af4SBart Van Assche */ 621e80a0af4SBart Van Assche struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp, 622e80a0af4SBart Van Assche unsigned int *nent_p) 623e80a0af4SBart Van Assche { 624e80a0af4SBart Van Assche return sgl_alloc_order(length, 0, false, gfp, nent_p); 625e80a0af4SBart Van Assche } 626e80a0af4SBart Van Assche EXPORT_SYMBOL(sgl_alloc); 627e80a0af4SBart Van Assche 628e80a0af4SBart Van Assche /** 6298c7a8d1cSBart Van Assche * sgl_free_n_order - free a scatterlist and its pages 6308c7a8d1cSBart Van Assche * @sgl: Scatterlist with one or more elements 6318c7a8d1cSBart Van Assche * @nents: Maximum number of elements to free 6328c7a8d1cSBart Van Assche * @order: Second argument for __free_pages() 6338c7a8d1cSBart Van Assche * 6348c7a8d1cSBart Van Assche * Notes: 6358c7a8d1cSBart Van Assche * - If several scatterlists have been chained and each chain element is 6368c7a8d1cSBart Van Assche * freed separately then it's essential to set nents correctly to avoid that a 6378c7a8d1cSBart Van Assche * page would get freed twice. 6388c7a8d1cSBart Van Assche * - All pages in a chained scatterlist can be freed at once by setting @nents 6398c7a8d1cSBart Van Assche * to a high number. 6408c7a8d1cSBart Van Assche */ 6418c7a8d1cSBart Van Assche void sgl_free_n_order(struct scatterlist *sgl, int nents, int order) 6428c7a8d1cSBart Van Assche { 6438c7a8d1cSBart Van Assche struct scatterlist *sg; 6448c7a8d1cSBart Van Assche struct page *page; 6458c7a8d1cSBart Van Assche int i; 6468c7a8d1cSBart Van Assche 6478c7a8d1cSBart Van Assche for_each_sg(sgl, sg, nents, i) { 6488c7a8d1cSBart Van Assche if (!sg) 6498c7a8d1cSBart Van Assche break; 6508c7a8d1cSBart Van Assche page = sg_page(sg); 6518c7a8d1cSBart Van Assche if (page) 6528c7a8d1cSBart Van Assche __free_pages(page, order); 6538c7a8d1cSBart Van Assche } 6548c7a8d1cSBart Van Assche kfree(sgl); 6558c7a8d1cSBart Van Assche } 6568c7a8d1cSBart Van Assche EXPORT_SYMBOL(sgl_free_n_order); 6578c7a8d1cSBart Van Assche 6588c7a8d1cSBart Van Assche /** 659e80a0af4SBart Van Assche * sgl_free_order - free a scatterlist and its pages 660e80a0af4SBart Van Assche * @sgl: Scatterlist with one or more elements 661e80a0af4SBart Van Assche * @order: Second argument for __free_pages() 662e80a0af4SBart Van Assche */ 663e80a0af4SBart Van Assche void sgl_free_order(struct scatterlist *sgl, int order) 664e80a0af4SBart Van Assche { 6658c7a8d1cSBart Van Assche sgl_free_n_order(sgl, INT_MAX, order); 666e80a0af4SBart Van Assche } 667e80a0af4SBart Van Assche EXPORT_SYMBOL(sgl_free_order); 668e80a0af4SBart Van Assche 669e80a0af4SBart Van Assche /** 670e80a0af4SBart Van Assche * sgl_free - free a scatterlist and its pages 671e80a0af4SBart Van Assche * @sgl: Scatterlist with one or more elements 672e80a0af4SBart Van Assche */ 673e80a0af4SBart Van Assche void sgl_free(struct scatterlist *sgl) 674e80a0af4SBart Van Assche { 675e80a0af4SBart Van Assche sgl_free_order(sgl, 0); 676e80a0af4SBart Van Assche } 677e80a0af4SBart Van Assche EXPORT_SYMBOL(sgl_free); 678e80a0af4SBart Van Assche 679e80a0af4SBart Van Assche #endif /* CONFIG_SGL_ALLOC */ 680e80a0af4SBart Van Assche 681a321e91bSImre Deak void __sg_page_iter_start(struct sg_page_iter *piter, 682a321e91bSImre Deak struct scatterlist *sglist, unsigned int nents, 683a321e91bSImre Deak unsigned long pgoffset) 684a321e91bSImre Deak { 685a321e91bSImre Deak piter->__pg_advance = 0; 686a321e91bSImre Deak piter->__nents = nents; 687a321e91bSImre Deak 688a321e91bSImre Deak piter->sg = sglist; 689a321e91bSImre Deak piter->sg_pgoffset = pgoffset; 690a321e91bSImre Deak } 691a321e91bSImre Deak EXPORT_SYMBOL(__sg_page_iter_start); 692a321e91bSImre Deak 693a321e91bSImre Deak static int sg_page_count(struct scatterlist *sg) 694a321e91bSImre Deak { 695a321e91bSImre Deak return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT; 696a321e91bSImre Deak } 697a321e91bSImre Deak 698a321e91bSImre Deak bool __sg_page_iter_next(struct sg_page_iter *piter) 699a321e91bSImre Deak { 700a321e91bSImre Deak if (!piter->__nents || !piter->sg) 701a321e91bSImre Deak return false; 702a321e91bSImre Deak 703a321e91bSImre Deak piter->sg_pgoffset += piter->__pg_advance; 704a321e91bSImre Deak piter->__pg_advance = 1; 705a321e91bSImre Deak 706a321e91bSImre Deak while (piter->sg_pgoffset >= sg_page_count(piter->sg)) { 707a321e91bSImre Deak piter->sg_pgoffset -= sg_page_count(piter->sg); 708a321e91bSImre Deak piter->sg = sg_next(piter->sg); 709a321e91bSImre Deak if (!--piter->__nents || !piter->sg) 710a321e91bSImre Deak return false; 711a321e91bSImre Deak } 712a321e91bSImre Deak 713a321e91bSImre Deak return true; 714a321e91bSImre Deak } 715a321e91bSImre Deak EXPORT_SYMBOL(__sg_page_iter_next); 716a321e91bSImre Deak 717d901b276SJason Gunthorpe static int sg_dma_page_count(struct scatterlist *sg) 718d901b276SJason Gunthorpe { 719d901b276SJason Gunthorpe return PAGE_ALIGN(sg->offset + sg_dma_len(sg)) >> PAGE_SHIFT; 720d901b276SJason Gunthorpe } 721d901b276SJason Gunthorpe 722d901b276SJason Gunthorpe bool __sg_page_iter_dma_next(struct sg_dma_page_iter *dma_iter) 723d901b276SJason Gunthorpe { 724d901b276SJason Gunthorpe struct sg_page_iter *piter = &dma_iter->base; 725d901b276SJason Gunthorpe 726d901b276SJason Gunthorpe if (!piter->__nents || !piter->sg) 727d901b276SJason Gunthorpe return false; 728d901b276SJason Gunthorpe 729d901b276SJason Gunthorpe piter->sg_pgoffset += piter->__pg_advance; 730d901b276SJason Gunthorpe piter->__pg_advance = 1; 731d901b276SJason Gunthorpe 732d901b276SJason Gunthorpe while (piter->sg_pgoffset >= sg_dma_page_count(piter->sg)) { 733d901b276SJason Gunthorpe piter->sg_pgoffset -= sg_dma_page_count(piter->sg); 734d901b276SJason Gunthorpe piter->sg = sg_next(piter->sg); 735d901b276SJason Gunthorpe if (!--piter->__nents || !piter->sg) 736d901b276SJason Gunthorpe return false; 737d901b276SJason Gunthorpe } 738d901b276SJason Gunthorpe 739d901b276SJason Gunthorpe return true; 740d901b276SJason Gunthorpe } 741d901b276SJason Gunthorpe EXPORT_SYMBOL(__sg_page_iter_dma_next); 742d901b276SJason Gunthorpe 743efc42bc9STomasz Stanislawski /** 744137d3edbSTejun Heo * sg_miter_start - start mapping iteration over a sg list 745137d3edbSTejun Heo * @miter: sg mapping iter to be started 746137d3edbSTejun Heo * @sgl: sg list to iterate over 747137d3edbSTejun Heo * @nents: number of sg entries 748137d3edbSTejun Heo * 749137d3edbSTejun Heo * Description: 750137d3edbSTejun Heo * Starts mapping iterator @miter. 751137d3edbSTejun Heo * 752137d3edbSTejun Heo * Context: 753137d3edbSTejun Heo * Don't care. 754137d3edbSTejun Heo */ 755137d3edbSTejun Heo void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl, 756137d3edbSTejun Heo unsigned int nents, unsigned int flags) 757137d3edbSTejun Heo { 758137d3edbSTejun Heo memset(miter, 0, sizeof(struct sg_mapping_iter)); 759137d3edbSTejun Heo 7604225fc85SImre Deak __sg_page_iter_start(&miter->piter, sgl, nents, 0); 7616de7e356SSebastian Andrzej Siewior WARN_ON(!(flags & (SG_MITER_TO_SG | SG_MITER_FROM_SG))); 762137d3edbSTejun Heo miter->__flags = flags; 763137d3edbSTejun Heo } 764137d3edbSTejun Heo EXPORT_SYMBOL(sg_miter_start); 765137d3edbSTejun Heo 76611052004SAkinobu Mita static bool sg_miter_get_next_page(struct sg_mapping_iter *miter) 76711052004SAkinobu Mita { 76811052004SAkinobu Mita if (!miter->__remaining) { 76911052004SAkinobu Mita struct scatterlist *sg; 77011052004SAkinobu Mita 77111052004SAkinobu Mita if (!__sg_page_iter_next(&miter->piter)) 77211052004SAkinobu Mita return false; 77311052004SAkinobu Mita 77411052004SAkinobu Mita sg = miter->piter.sg; 77511052004SAkinobu Mita 776aeb87246SChristophe Leroy miter->__offset = miter->piter.sg_pgoffset ? 0 : sg->offset; 777aeb87246SChristophe Leroy miter->piter.sg_pgoffset += miter->__offset >> PAGE_SHIFT; 778aeb87246SChristophe Leroy miter->__offset &= PAGE_SIZE - 1; 77911052004SAkinobu Mita miter->__remaining = sg->offset + sg->length - 780aeb87246SChristophe Leroy (miter->piter.sg_pgoffset << PAGE_SHIFT) - 781aeb87246SChristophe Leroy miter->__offset; 78211052004SAkinobu Mita miter->__remaining = min_t(unsigned long, miter->__remaining, 78311052004SAkinobu Mita PAGE_SIZE - miter->__offset); 78411052004SAkinobu Mita } 78511052004SAkinobu Mita 78611052004SAkinobu Mita return true; 78711052004SAkinobu Mita } 78811052004SAkinobu Mita 789137d3edbSTejun Heo /** 790df642ceaSAkinobu Mita * sg_miter_skip - reposition mapping iterator 791df642ceaSAkinobu Mita * @miter: sg mapping iter to be skipped 792df642ceaSAkinobu Mita * @offset: number of bytes to plus the current location 793df642ceaSAkinobu Mita * 794df642ceaSAkinobu Mita * Description: 795df642ceaSAkinobu Mita * Sets the offset of @miter to its current location plus @offset bytes. 796df642ceaSAkinobu Mita * If mapping iterator @miter has been proceeded by sg_miter_next(), this 797df642ceaSAkinobu Mita * stops @miter. 798df642ceaSAkinobu Mita * 799df642ceaSAkinobu Mita * Context: 800df642ceaSAkinobu Mita * Don't care if @miter is stopped, or not proceeded yet. 801df642ceaSAkinobu Mita * Otherwise, preemption disabled if the SG_MITER_ATOMIC is set. 802df642ceaSAkinobu Mita * 803df642ceaSAkinobu Mita * Returns: 804df642ceaSAkinobu Mita * true if @miter contains the valid mapping. false if end of sg 805df642ceaSAkinobu Mita * list is reached. 806df642ceaSAkinobu Mita */ 8070d6077f8SMing Lei bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset) 808df642ceaSAkinobu Mita { 809df642ceaSAkinobu Mita sg_miter_stop(miter); 810df642ceaSAkinobu Mita 811df642ceaSAkinobu Mita while (offset) { 812df642ceaSAkinobu Mita off_t consumed; 813df642ceaSAkinobu Mita 814df642ceaSAkinobu Mita if (!sg_miter_get_next_page(miter)) 815df642ceaSAkinobu Mita return false; 816df642ceaSAkinobu Mita 817df642ceaSAkinobu Mita consumed = min_t(off_t, offset, miter->__remaining); 818df642ceaSAkinobu Mita miter->__offset += consumed; 819df642ceaSAkinobu Mita miter->__remaining -= consumed; 820df642ceaSAkinobu Mita offset -= consumed; 821df642ceaSAkinobu Mita } 822df642ceaSAkinobu Mita 823df642ceaSAkinobu Mita return true; 824df642ceaSAkinobu Mita } 8250d6077f8SMing Lei EXPORT_SYMBOL(sg_miter_skip); 826df642ceaSAkinobu Mita 827df642ceaSAkinobu Mita /** 828137d3edbSTejun Heo * sg_miter_next - proceed mapping iterator to the next mapping 829137d3edbSTejun Heo * @miter: sg mapping iter to proceed 830137d3edbSTejun Heo * 831137d3edbSTejun Heo * Description: 8328290e2d2STejun Heo * Proceeds @miter to the next mapping. @miter should have been started 8338290e2d2STejun Heo * using sg_miter_start(). On successful return, @miter->page, 8348290e2d2STejun Heo * @miter->addr and @miter->length point to the current mapping. 835137d3edbSTejun Heo * 836137d3edbSTejun Heo * Context: 8378290e2d2STejun Heo * Preemption disabled if SG_MITER_ATOMIC. Preemption must stay disabled 8388290e2d2STejun Heo * till @miter is stopped. May sleep if !SG_MITER_ATOMIC. 839137d3edbSTejun Heo * 840137d3edbSTejun Heo * Returns: 841137d3edbSTejun Heo * true if @miter contains the next mapping. false if end of sg 842137d3edbSTejun Heo * list is reached. 843137d3edbSTejun Heo */ 844137d3edbSTejun Heo bool sg_miter_next(struct sg_mapping_iter *miter) 845137d3edbSTejun Heo { 846137d3edbSTejun Heo sg_miter_stop(miter); 847137d3edbSTejun Heo 8484225fc85SImre Deak /* 8494225fc85SImre Deak * Get to the next page if necessary. 8504225fc85SImre Deak * __remaining, __offset is adjusted by sg_miter_stop 8514225fc85SImre Deak */ 85211052004SAkinobu Mita if (!sg_miter_get_next_page(miter)) 85323c560a9STejun Heo return false; 8544225fc85SImre Deak 8552db76d7cSImre Deak miter->page = sg_page_iter_page(&miter->piter); 8564225fc85SImre Deak miter->consumed = miter->length = miter->__remaining; 857137d3edbSTejun Heo 858137d3edbSTejun Heo if (miter->__flags & SG_MITER_ATOMIC) 8594225fc85SImre Deak miter->addr = kmap_atomic(miter->page) + miter->__offset; 860137d3edbSTejun Heo else 8614225fc85SImre Deak miter->addr = kmap(miter->page) + miter->__offset; 862137d3edbSTejun Heo 863137d3edbSTejun Heo return true; 864137d3edbSTejun Heo } 865137d3edbSTejun Heo EXPORT_SYMBOL(sg_miter_next); 866137d3edbSTejun Heo 867137d3edbSTejun Heo /** 868137d3edbSTejun Heo * sg_miter_stop - stop mapping iteration 869137d3edbSTejun Heo * @miter: sg mapping iter to be stopped 870137d3edbSTejun Heo * 871137d3edbSTejun Heo * Description: 872137d3edbSTejun Heo * Stops mapping iterator @miter. @miter should have been started 8734ba6a2b2SMasahiro Yamada * using sg_miter_start(). A stopped iteration can be resumed by 8744ba6a2b2SMasahiro Yamada * calling sg_miter_next() on it. This is useful when resources (kmap) 8754ba6a2b2SMasahiro Yamada * need to be released during iteration. 876137d3edbSTejun Heo * 877137d3edbSTejun Heo * Context: 8788290e2d2STejun Heo * Preemption disabled if the SG_MITER_ATOMIC is set. Don't care 8798290e2d2STejun Heo * otherwise. 880137d3edbSTejun Heo */ 881137d3edbSTejun Heo void sg_miter_stop(struct sg_mapping_iter *miter) 882137d3edbSTejun Heo { 883137d3edbSTejun Heo WARN_ON(miter->consumed > miter->length); 884137d3edbSTejun Heo 885137d3edbSTejun Heo /* drop resources from the last iteration */ 886137d3edbSTejun Heo if (miter->addr) { 887137d3edbSTejun Heo miter->__offset += miter->consumed; 8884225fc85SImre Deak miter->__remaining -= miter->consumed; 889137d3edbSTejun Heo 8903d77b50cSMing Lei if ((miter->__flags & SG_MITER_TO_SG) && 8913d77b50cSMing Lei !PageSlab(miter->page)) 8926de7e356SSebastian Andrzej Siewior flush_kernel_dcache_page(miter->page); 8936de7e356SSebastian Andrzej Siewior 894137d3edbSTejun Heo if (miter->__flags & SG_MITER_ATOMIC) { 8958290e2d2STejun Heo WARN_ON_ONCE(preemptible()); 896c3eede8eSCong Wang kunmap_atomic(miter->addr); 897137d3edbSTejun Heo } else 898f652c521SArjan van de Ven kunmap(miter->page); 899137d3edbSTejun Heo 900137d3edbSTejun Heo miter->page = NULL; 901137d3edbSTejun Heo miter->addr = NULL; 902137d3edbSTejun Heo miter->length = 0; 903137d3edbSTejun Heo miter->consumed = 0; 904137d3edbSTejun Heo } 905137d3edbSTejun Heo } 906137d3edbSTejun Heo EXPORT_SYMBOL(sg_miter_stop); 907137d3edbSTejun Heo 908137d3edbSTejun Heo /** 909b1adaf65SFUJITA Tomonori * sg_copy_buffer - Copy data between a linear buffer and an SG list 910b1adaf65SFUJITA Tomonori * @sgl: The SG list 911b1adaf65SFUJITA Tomonori * @nents: Number of SG entries 912b1adaf65SFUJITA Tomonori * @buf: Where to copy from 913b1adaf65SFUJITA Tomonori * @buflen: The number of bytes to copy 914df642ceaSAkinobu Mita * @skip: Number of bytes to skip before copying 915df642ceaSAkinobu Mita * @to_buffer: transfer direction (true == from an sg list to a 9166e853185SGeert Uytterhoeven * buffer, false == from a buffer to an sg list) 917b1adaf65SFUJITA Tomonori * 918b1adaf65SFUJITA Tomonori * Returns the number of copied bytes. 919b1adaf65SFUJITA Tomonori * 920b1adaf65SFUJITA Tomonori **/ 921386ecb12SDave Gordon size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf, 922386ecb12SDave Gordon size_t buflen, off_t skip, bool to_buffer) 923b1adaf65SFUJITA Tomonori { 924137d3edbSTejun Heo unsigned int offset = 0; 925137d3edbSTejun Heo struct sg_mapping_iter miter; 9266de7e356SSebastian Andrzej Siewior unsigned int sg_flags = SG_MITER_ATOMIC; 927b1adaf65SFUJITA Tomonori 9286de7e356SSebastian Andrzej Siewior if (to_buffer) 9296de7e356SSebastian Andrzej Siewior sg_flags |= SG_MITER_FROM_SG; 9306de7e356SSebastian Andrzej Siewior else 9316de7e356SSebastian Andrzej Siewior sg_flags |= SG_MITER_TO_SG; 9326de7e356SSebastian Andrzej Siewior 9336de7e356SSebastian Andrzej Siewior sg_miter_start(&miter, sgl, nents, sg_flags); 934b1adaf65SFUJITA Tomonori 935df642ceaSAkinobu Mita if (!sg_miter_skip(&miter, skip)) 9361f41be7dSDavid Disseldorp return 0; 937df642ceaSAkinobu Mita 9381d5210efSGilad Ben-Yossef while ((offset < buflen) && sg_miter_next(&miter)) { 939137d3edbSTejun Heo unsigned int len; 940b1adaf65SFUJITA Tomonori 941137d3edbSTejun Heo len = min(miter.length, buflen - offset); 942b1adaf65SFUJITA Tomonori 943b1adaf65SFUJITA Tomonori if (to_buffer) 944137d3edbSTejun Heo memcpy(buf + offset, miter.addr, len); 9456de7e356SSebastian Andrzej Siewior else 946137d3edbSTejun Heo memcpy(miter.addr, buf + offset, len); 947b1adaf65SFUJITA Tomonori 948137d3edbSTejun Heo offset += len; 949b1adaf65SFUJITA Tomonori } 950b1adaf65SFUJITA Tomonori 951137d3edbSTejun Heo sg_miter_stop(&miter); 952b1adaf65SFUJITA Tomonori 953137d3edbSTejun Heo return offset; 954b1adaf65SFUJITA Tomonori } 955386ecb12SDave Gordon EXPORT_SYMBOL(sg_copy_buffer); 956b1adaf65SFUJITA Tomonori 957b1adaf65SFUJITA Tomonori /** 958b1adaf65SFUJITA Tomonori * sg_copy_from_buffer - Copy from a linear buffer to an SG list 959b1adaf65SFUJITA Tomonori * @sgl: The SG list 960b1adaf65SFUJITA Tomonori * @nents: Number of SG entries 961b1adaf65SFUJITA Tomonori * @buf: Where to copy from 962b1adaf65SFUJITA Tomonori * @buflen: The number of bytes to copy 963b1adaf65SFUJITA Tomonori * 964b1adaf65SFUJITA Tomonori * Returns the number of copied bytes. 965b1adaf65SFUJITA Tomonori * 966b1adaf65SFUJITA Tomonori **/ 967b1adaf65SFUJITA Tomonori size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents, 9682a1bf8f9SDave Gordon const void *buf, size_t buflen) 969b1adaf65SFUJITA Tomonori { 9702a1bf8f9SDave Gordon return sg_copy_buffer(sgl, nents, (void *)buf, buflen, 0, false); 971b1adaf65SFUJITA Tomonori } 972b1adaf65SFUJITA Tomonori EXPORT_SYMBOL(sg_copy_from_buffer); 973b1adaf65SFUJITA Tomonori 974b1adaf65SFUJITA Tomonori /** 975b1adaf65SFUJITA Tomonori * sg_copy_to_buffer - Copy from an SG list to a linear buffer 976b1adaf65SFUJITA Tomonori * @sgl: The SG list 977b1adaf65SFUJITA Tomonori * @nents: Number of SG entries 978b1adaf65SFUJITA Tomonori * @buf: Where to copy to 979b1adaf65SFUJITA Tomonori * @buflen: The number of bytes to copy 980b1adaf65SFUJITA Tomonori * 981b1adaf65SFUJITA Tomonori * Returns the number of copied bytes. 982b1adaf65SFUJITA Tomonori * 983b1adaf65SFUJITA Tomonori **/ 984b1adaf65SFUJITA Tomonori size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents, 985b1adaf65SFUJITA Tomonori void *buf, size_t buflen) 986b1adaf65SFUJITA Tomonori { 987df642ceaSAkinobu Mita return sg_copy_buffer(sgl, nents, buf, buflen, 0, true); 988b1adaf65SFUJITA Tomonori } 989b1adaf65SFUJITA Tomonori EXPORT_SYMBOL(sg_copy_to_buffer); 990df642ceaSAkinobu Mita 991df642ceaSAkinobu Mita /** 992df642ceaSAkinobu Mita * sg_pcopy_from_buffer - Copy from a linear buffer to an SG list 993df642ceaSAkinobu Mita * @sgl: The SG list 994df642ceaSAkinobu Mita * @nents: Number of SG entries 995df642ceaSAkinobu Mita * @buf: Where to copy from 996df642ceaSAkinobu Mita * @buflen: The number of bytes to copy 9974dc7daf8SDave Gordon * @skip: Number of bytes to skip before copying 998df642ceaSAkinobu Mita * 999df642ceaSAkinobu Mita * Returns the number of copied bytes. 1000df642ceaSAkinobu Mita * 1001df642ceaSAkinobu Mita **/ 1002df642ceaSAkinobu Mita size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents, 10032a1bf8f9SDave Gordon const void *buf, size_t buflen, off_t skip) 1004df642ceaSAkinobu Mita { 10052a1bf8f9SDave Gordon return sg_copy_buffer(sgl, nents, (void *)buf, buflen, skip, false); 1006df642ceaSAkinobu Mita } 1007df642ceaSAkinobu Mita EXPORT_SYMBOL(sg_pcopy_from_buffer); 1008df642ceaSAkinobu Mita 1009df642ceaSAkinobu Mita /** 1010df642ceaSAkinobu Mita * sg_pcopy_to_buffer - Copy from an SG list to a linear buffer 1011df642ceaSAkinobu Mita * @sgl: The SG list 1012df642ceaSAkinobu Mita * @nents: Number of SG entries 1013df642ceaSAkinobu Mita * @buf: Where to copy to 1014df642ceaSAkinobu Mita * @buflen: The number of bytes to copy 10154dc7daf8SDave Gordon * @skip: Number of bytes to skip before copying 1016df642ceaSAkinobu Mita * 1017df642ceaSAkinobu Mita * Returns the number of copied bytes. 1018df642ceaSAkinobu Mita * 1019df642ceaSAkinobu Mita **/ 1020df642ceaSAkinobu Mita size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents, 1021df642ceaSAkinobu Mita void *buf, size_t buflen, off_t skip) 1022df642ceaSAkinobu Mita { 1023df642ceaSAkinobu Mita return sg_copy_buffer(sgl, nents, buf, buflen, skip, true); 1024df642ceaSAkinobu Mita } 1025df642ceaSAkinobu Mita EXPORT_SYMBOL(sg_pcopy_to_buffer); 10260945e569SJohannes Thumshirn 10270945e569SJohannes Thumshirn /** 10280945e569SJohannes Thumshirn * sg_zero_buffer - Zero-out a part of a SG list 10290945e569SJohannes Thumshirn * @sgl: The SG list 10300945e569SJohannes Thumshirn * @nents: Number of SG entries 10310945e569SJohannes Thumshirn * @buflen: The number of bytes to zero out 10320945e569SJohannes Thumshirn * @skip: Number of bytes to skip before zeroing 10330945e569SJohannes Thumshirn * 10340945e569SJohannes Thumshirn * Returns the number of bytes zeroed. 10350945e569SJohannes Thumshirn **/ 10360945e569SJohannes Thumshirn size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents, 10370945e569SJohannes Thumshirn size_t buflen, off_t skip) 10380945e569SJohannes Thumshirn { 10390945e569SJohannes Thumshirn unsigned int offset = 0; 10400945e569SJohannes Thumshirn struct sg_mapping_iter miter; 10410945e569SJohannes Thumshirn unsigned int sg_flags = SG_MITER_ATOMIC | SG_MITER_TO_SG; 10420945e569SJohannes Thumshirn 10430945e569SJohannes Thumshirn sg_miter_start(&miter, sgl, nents, sg_flags); 10440945e569SJohannes Thumshirn 10450945e569SJohannes Thumshirn if (!sg_miter_skip(&miter, skip)) 10460945e569SJohannes Thumshirn return false; 10470945e569SJohannes Thumshirn 10480945e569SJohannes Thumshirn while (offset < buflen && sg_miter_next(&miter)) { 10490945e569SJohannes Thumshirn unsigned int len; 10500945e569SJohannes Thumshirn 10510945e569SJohannes Thumshirn len = min(miter.length, buflen - offset); 10520945e569SJohannes Thumshirn memset(miter.addr, 0, len); 10530945e569SJohannes Thumshirn 10540945e569SJohannes Thumshirn offset += len; 10550945e569SJohannes Thumshirn } 10560945e569SJohannes Thumshirn 10570945e569SJohannes Thumshirn sg_miter_stop(&miter); 10580945e569SJohannes Thumshirn return offset; 10590945e569SJohannes Thumshirn } 10600945e569SJohannes Thumshirn EXPORT_SYMBOL(sg_zero_buffer); 1061