iov_iter.c revision 71d8e532b1549a478e6a6a8a44f309d050294d00
14f18cd317a118c28482f97303600a2fe2ada6c79Al Viro#include <linux/export.h> 24f18cd317a118c28482f97303600a2fe2ada6c79Al Viro#include <linux/uio.h> 34f18cd317a118c28482f97303600a2fe2ada6c79Al Viro#include <linux/pagemap.h> 44f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 54f18cd317a118c28482f97303600a2fe2ada6c79Al Virosize_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, 64f18cd317a118c28482f97303600a2fe2ada6c79Al Viro struct iov_iter *i) 74f18cd317a118c28482f97303600a2fe2ada6c79Al Viro{ 84f18cd317a118c28482f97303600a2fe2ada6c79Al Viro size_t skip, copy, left, wanted; 94f18cd317a118c28482f97303600a2fe2ada6c79Al Viro const struct iovec *iov; 104f18cd317a118c28482f97303600a2fe2ada6c79Al Viro char __user *buf; 114f18cd317a118c28482f97303600a2fe2ada6c79Al Viro void *kaddr, *from; 124f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 134f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (unlikely(bytes > i->count)) 144f18cd317a118c28482f97303600a2fe2ada6c79Al Viro bytes = i->count; 154f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 164f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (unlikely(!bytes)) 174f18cd317a118c28482f97303600a2fe2ada6c79Al Viro return 0; 184f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 194f18cd317a118c28482f97303600a2fe2ada6c79Al Viro wanted = bytes; 204f18cd317a118c28482f97303600a2fe2ada6c79Al Viro iov = i->iov; 214f18cd317a118c28482f97303600a2fe2ada6c79Al Viro skip = i->iov_offset; 224f18cd317a118c28482f97303600a2fe2ada6c79Al Viro buf = iov->iov_base + skip; 234f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy = min(bytes, iov->iov_len - skip); 244f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 254f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (!fault_in_pages_writeable(buf, copy)) { 264f18cd317a118c28482f97303600a2fe2ada6c79Al Viro kaddr = kmap_atomic(page); 274f18cd317a118c28482f97303600a2fe2ada6c79Al Viro from = kaddr + offset; 284f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 294f18cd317a118c28482f97303600a2fe2ada6c79Al Viro /* first chunk, usually the only one */ 304f18cd317a118c28482f97303600a2fe2ada6c79Al Viro left = __copy_to_user_inatomic(buf, from, copy); 314f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy -= left; 324f18cd317a118c28482f97303600a2fe2ada6c79Al Viro skip += copy; 334f18cd317a118c28482f97303600a2fe2ada6c79Al Viro from += copy; 344f18cd317a118c28482f97303600a2fe2ada6c79Al Viro bytes -= copy; 354f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 364f18cd317a118c28482f97303600a2fe2ada6c79Al Viro while (unlikely(!left && bytes)) { 374f18cd317a118c28482f97303600a2fe2ada6c79Al Viro iov++; 384f18cd317a118c28482f97303600a2fe2ada6c79Al Viro buf = iov->iov_base; 394f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy = min(bytes, iov->iov_len); 404f18cd317a118c28482f97303600a2fe2ada6c79Al Viro left = __copy_to_user_inatomic(buf, from, copy); 414f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy -= left; 424f18cd317a118c28482f97303600a2fe2ada6c79Al Viro skip = copy; 434f18cd317a118c28482f97303600a2fe2ada6c79Al Viro from += copy; 444f18cd317a118c28482f97303600a2fe2ada6c79Al Viro bytes -= copy; 454f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 464f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (likely(!bytes)) { 474f18cd317a118c28482f97303600a2fe2ada6c79Al Viro kunmap_atomic(kaddr); 484f18cd317a118c28482f97303600a2fe2ada6c79Al Viro goto done; 494f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 504f18cd317a118c28482f97303600a2fe2ada6c79Al Viro offset = from - kaddr; 514f18cd317a118c28482f97303600a2fe2ada6c79Al Viro buf += copy; 524f18cd317a118c28482f97303600a2fe2ada6c79Al Viro kunmap_atomic(kaddr); 534f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy = min(bytes, iov->iov_len - skip); 544f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 554f18cd317a118c28482f97303600a2fe2ada6c79Al Viro /* Too bad - revert to non-atomic kmap */ 564f18cd317a118c28482f97303600a2fe2ada6c79Al Viro kaddr = kmap(page); 574f18cd317a118c28482f97303600a2fe2ada6c79Al Viro from = kaddr + offset; 584f18cd317a118c28482f97303600a2fe2ada6c79Al Viro left = __copy_to_user(buf, from, copy); 594f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy -= left; 604f18cd317a118c28482f97303600a2fe2ada6c79Al Viro skip += copy; 614f18cd317a118c28482f97303600a2fe2ada6c79Al Viro from += copy; 624f18cd317a118c28482f97303600a2fe2ada6c79Al Viro bytes -= copy; 634f18cd317a118c28482f97303600a2fe2ada6c79Al Viro while (unlikely(!left && bytes)) { 644f18cd317a118c28482f97303600a2fe2ada6c79Al Viro iov++; 654f18cd317a118c28482f97303600a2fe2ada6c79Al Viro buf = iov->iov_base; 664f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy = min(bytes, iov->iov_len); 674f18cd317a118c28482f97303600a2fe2ada6c79Al Viro left = __copy_to_user(buf, from, copy); 684f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy -= left; 694f18cd317a118c28482f97303600a2fe2ada6c79Al Viro skip = copy; 704f18cd317a118c28482f97303600a2fe2ada6c79Al Viro from += copy; 714f18cd317a118c28482f97303600a2fe2ada6c79Al Viro bytes -= copy; 724f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 734f18cd317a118c28482f97303600a2fe2ada6c79Al Viro kunmap(page); 744f18cd317a118c28482f97303600a2fe2ada6c79Al Virodone: 754f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->count -= wanted - bytes; 764f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->nr_segs -= iov - i->iov; 774f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->iov = iov; 784f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->iov_offset = skip; 794f18cd317a118c28482f97303600a2fe2ada6c79Al Viro return wanted - bytes; 804f18cd317a118c28482f97303600a2fe2ada6c79Al Viro} 814f18cd317a118c28482f97303600a2fe2ada6c79Al ViroEXPORT_SYMBOL(copy_page_to_iter); 824f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 834f18cd317a118c28482f97303600a2fe2ada6c79Al Virostatic size_t __iovec_copy_from_user_inatomic(char *vaddr, 844f18cd317a118c28482f97303600a2fe2ada6c79Al Viro const struct iovec *iov, size_t base, size_t bytes) 854f18cd317a118c28482f97303600a2fe2ada6c79Al Viro{ 864f18cd317a118c28482f97303600a2fe2ada6c79Al Viro size_t copied = 0, left = 0; 874f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 884f18cd317a118c28482f97303600a2fe2ada6c79Al Viro while (bytes) { 894f18cd317a118c28482f97303600a2fe2ada6c79Al Viro char __user *buf = iov->iov_base + base; 904f18cd317a118c28482f97303600a2fe2ada6c79Al Viro int copy = min(bytes, iov->iov_len - base); 914f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 924f18cd317a118c28482f97303600a2fe2ada6c79Al Viro base = 0; 934f18cd317a118c28482f97303600a2fe2ada6c79Al Viro left = __copy_from_user_inatomic(vaddr, buf, copy); 944f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copied += copy; 954f18cd317a118c28482f97303600a2fe2ada6c79Al Viro bytes -= copy; 964f18cd317a118c28482f97303600a2fe2ada6c79Al Viro vaddr += copy; 974f18cd317a118c28482f97303600a2fe2ada6c79Al Viro iov++; 984f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 994f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (unlikely(left)) 1004f18cd317a118c28482f97303600a2fe2ada6c79Al Viro break; 1014f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 1024f18cd317a118c28482f97303600a2fe2ada6c79Al Viro return copied - left; 1034f18cd317a118c28482f97303600a2fe2ada6c79Al Viro} 1044f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 1054f18cd317a118c28482f97303600a2fe2ada6c79Al Viro/* 1064f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * Copy as much as we can into the page and return the number of bytes which 1074f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * were successfully copied. If a fault is encountered then return the number of 1084f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * bytes which were copied. 1094f18cd317a118c28482f97303600a2fe2ada6c79Al Viro */ 1104f18cd317a118c28482f97303600a2fe2ada6c79Al Virosize_t iov_iter_copy_from_user_atomic(struct page *page, 1114f18cd317a118c28482f97303600a2fe2ada6c79Al Viro struct iov_iter *i, unsigned long offset, size_t bytes) 1124f18cd317a118c28482f97303600a2fe2ada6c79Al Viro{ 1134f18cd317a118c28482f97303600a2fe2ada6c79Al Viro char *kaddr; 1144f18cd317a118c28482f97303600a2fe2ada6c79Al Viro size_t copied; 1154f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 1164f18cd317a118c28482f97303600a2fe2ada6c79Al Viro kaddr = kmap_atomic(page); 1174f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (likely(i->nr_segs == 1)) { 1184f18cd317a118c28482f97303600a2fe2ada6c79Al Viro int left; 1194f18cd317a118c28482f97303600a2fe2ada6c79Al Viro char __user *buf = i->iov->iov_base + i->iov_offset; 1204f18cd317a118c28482f97303600a2fe2ada6c79Al Viro left = __copy_from_user_inatomic(kaddr + offset, buf, bytes); 1214f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copied = bytes - left; 1224f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } else { 1234f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copied = __iovec_copy_from_user_inatomic(kaddr + offset, 1244f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->iov, i->iov_offset, bytes); 1254f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 1264f18cd317a118c28482f97303600a2fe2ada6c79Al Viro kunmap_atomic(kaddr); 1274f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 1284f18cd317a118c28482f97303600a2fe2ada6c79Al Viro return copied; 1294f18cd317a118c28482f97303600a2fe2ada6c79Al Viro} 1304f18cd317a118c28482f97303600a2fe2ada6c79Al ViroEXPORT_SYMBOL(iov_iter_copy_from_user_atomic); 1314f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 1324f18cd317a118c28482f97303600a2fe2ada6c79Al Virovoid iov_iter_advance(struct iov_iter *i, size_t bytes) 1334f18cd317a118c28482f97303600a2fe2ada6c79Al Viro{ 1344f18cd317a118c28482f97303600a2fe2ada6c79Al Viro BUG_ON(i->count < bytes); 1354f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 1364f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (likely(i->nr_segs == 1)) { 1374f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->iov_offset += bytes; 1384f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->count -= bytes; 1394f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } else { 1404f18cd317a118c28482f97303600a2fe2ada6c79Al Viro const struct iovec *iov = i->iov; 1414f18cd317a118c28482f97303600a2fe2ada6c79Al Viro size_t base = i->iov_offset; 1424f18cd317a118c28482f97303600a2fe2ada6c79Al Viro unsigned long nr_segs = i->nr_segs; 1434f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 1444f18cd317a118c28482f97303600a2fe2ada6c79Al Viro /* 1454f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * The !iov->iov_len check ensures we skip over unlikely 1464f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * zero-length segments (without overruning the iovec). 1474f18cd317a118c28482f97303600a2fe2ada6c79Al Viro */ 1484f18cd317a118c28482f97303600a2fe2ada6c79Al Viro while (bytes || unlikely(i->count && !iov->iov_len)) { 1494f18cd317a118c28482f97303600a2fe2ada6c79Al Viro int copy; 1504f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 1514f18cd317a118c28482f97303600a2fe2ada6c79Al Viro copy = min(bytes, iov->iov_len - base); 1524f18cd317a118c28482f97303600a2fe2ada6c79Al Viro BUG_ON(!i->count || i->count < copy); 1534f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->count -= copy; 1544f18cd317a118c28482f97303600a2fe2ada6c79Al Viro bytes -= copy; 1554f18cd317a118c28482f97303600a2fe2ada6c79Al Viro base += copy; 1564f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (iov->iov_len == base) { 1574f18cd317a118c28482f97303600a2fe2ada6c79Al Viro iov++; 1584f18cd317a118c28482f97303600a2fe2ada6c79Al Viro nr_segs--; 1594f18cd317a118c28482f97303600a2fe2ada6c79Al Viro base = 0; 1604f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 1614f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 1624f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->iov = iov; 1634f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->iov_offset = base; 1644f18cd317a118c28482f97303600a2fe2ada6c79Al Viro i->nr_segs = nr_segs; 1654f18cd317a118c28482f97303600a2fe2ada6c79Al Viro } 1664f18cd317a118c28482f97303600a2fe2ada6c79Al Viro} 1674f18cd317a118c28482f97303600a2fe2ada6c79Al ViroEXPORT_SYMBOL(iov_iter_advance); 1684f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 1694f18cd317a118c28482f97303600a2fe2ada6c79Al Viro/* 1704f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * Fault in the first iovec of the given iov_iter, to a maximum length 1714f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * of bytes. Returns 0 on success, or non-zero if the memory could not be 1724f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * accessed (ie. because it is an invalid address). 1734f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * 1744f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * writev-intensive code may want this to prefault several iovecs -- that 1754f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * would be possible (callers must not rely on the fact that _only_ the 1764f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * first iovec will be faulted with the current implementation). 1774f18cd317a118c28482f97303600a2fe2ada6c79Al Viro */ 1784f18cd317a118c28482f97303600a2fe2ada6c79Al Viroint iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes) 1794f18cd317a118c28482f97303600a2fe2ada6c79Al Viro{ 1804f18cd317a118c28482f97303600a2fe2ada6c79Al Viro char __user *buf = i->iov->iov_base + i->iov_offset; 1814f18cd317a118c28482f97303600a2fe2ada6c79Al Viro bytes = min(bytes, i->iov->iov_len - i->iov_offset); 1824f18cd317a118c28482f97303600a2fe2ada6c79Al Viro return fault_in_pages_readable(buf, bytes); 1834f18cd317a118c28482f97303600a2fe2ada6c79Al Viro} 1844f18cd317a118c28482f97303600a2fe2ada6c79Al ViroEXPORT_SYMBOL(iov_iter_fault_in_readable); 1854f18cd317a118c28482f97303600a2fe2ada6c79Al Viro 1864f18cd317a118c28482f97303600a2fe2ada6c79Al Viro/* 1874f18cd317a118c28482f97303600a2fe2ada6c79Al Viro * Return the count of just the current iov_iter segment. 1884f18cd317a118c28482f97303600a2fe2ada6c79Al Viro */ 1894f18cd317a118c28482f97303600a2fe2ada6c79Al Virosize_t iov_iter_single_seg_count(const struct iov_iter *i) 1904f18cd317a118c28482f97303600a2fe2ada6c79Al Viro{ 1914f18cd317a118c28482f97303600a2fe2ada6c79Al Viro const struct iovec *iov = i->iov; 1924f18cd317a118c28482f97303600a2fe2ada6c79Al Viro if (i->nr_segs == 1) 1934f18cd317a118c28482f97303600a2fe2ada6c79Al Viro return i->count; 1944f18cd317a118c28482f97303600a2fe2ada6c79Al Viro else 1954f18cd317a118c28482f97303600a2fe2ada6c79Al Viro return min(i->count, iov->iov_len - i->iov_offset); 1964f18cd317a118c28482f97303600a2fe2ada6c79Al Viro} 1974f18cd317a118c28482f97303600a2fe2ada6c79Al ViroEXPORT_SYMBOL(iov_iter_single_seg_count); 198886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro 199886a39115005ced8b15ab067c9c2a8d546b40a5eAl Virounsigned long iov_iter_alignment(const struct iov_iter *i) 200886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro{ 201886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro const struct iovec *iov = i->iov; 202886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro unsigned long res; 203886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro size_t size = i->count; 204886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro size_t n; 205886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro 206886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro if (!size) 207886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro return 0; 208886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro 209886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro res = (unsigned long)iov->iov_base + i->iov_offset; 210886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro n = iov->iov_len - i->iov_offset; 211886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro if (n >= size) 212886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro return res | size; 213886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro size -= n; 214886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro res |= n; 215886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro while (size > (++iov)->iov_len) { 216886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro res |= (unsigned long)iov->iov_base | iov->iov_len; 217886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro size -= iov->iov_len; 218886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro } 219886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro res |= (unsigned long)iov->iov_base | size; 220886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro return res; 221886a39115005ced8b15ab067c9c2a8d546b40a5eAl Viro} 222886a39115005ced8b15ab067c9c2a8d546b40a5eAl ViroEXPORT_SYMBOL(iov_iter_alignment); 22371d8e532b1549a478e6a6a8a44f309d050294d00Al Viro 22471d8e532b1549a478e6a6a8a44f309d050294d00Al Virovoid iov_iter_init(struct iov_iter *i, int direction, 22571d8e532b1549a478e6a6a8a44f309d050294d00Al Viro const struct iovec *iov, unsigned long nr_segs, 22671d8e532b1549a478e6a6a8a44f309d050294d00Al Viro size_t count) 22771d8e532b1549a478e6a6a8a44f309d050294d00Al Viro{ 22871d8e532b1549a478e6a6a8a44f309d050294d00Al Viro /* It will get better. Eventually... */ 22971d8e532b1549a478e6a6a8a44f309d050294d00Al Viro if (segment_eq(get_fs(), KERNEL_DS)) 23071d8e532b1549a478e6a6a8a44f309d050294d00Al Viro direction |= REQ_KERNEL; 23171d8e532b1549a478e6a6a8a44f309d050294d00Al Viro i->type = direction; 23271d8e532b1549a478e6a6a8a44f309d050294d00Al Viro i->iov = iov; 23371d8e532b1549a478e6a6a8a44f309d050294d00Al Viro i->nr_segs = nr_segs; 23471d8e532b1549a478e6a6a8a44f309d050294d00Al Viro i->iov_offset = 0; 23571d8e532b1549a478e6a6a8a44f309d050294d00Al Viro i->count = count; 23671d8e532b1549a478e6a6a8a44f309d050294d00Al Viro} 23771d8e532b1549a478e6a6a8a44f309d050294d00Al ViroEXPORT_SYMBOL(iov_iter_init); 238