diff options
Diffstat (limited to 'include/linux/uio.h')
-rw-r--r-- | include/linux/uio.h | 428 |
1 files changed, 428 insertions, 0 deletions
diff --git a/include/linux/uio.h b/include/linux/uio.h new file mode 100644 index 0000000000..42bce38a8e --- /dev/null +++ b/include/linux/uio.h @@ -0,0 +1,428 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Berkeley style UIO structures - Alan Cox 1994. + */ +#ifndef __LINUX_UIO_H +#define __LINUX_UIO_H + +#include <linux/kernel.h> +#include <linux/thread_info.h> +#include <linux/mm_types.h> +#include <uapi/linux/uio.h> + +struct page; + +typedef unsigned int __bitwise iov_iter_extraction_t; + +struct kvec { + void *iov_base; /* and that should *never* hold a userland pointer */ + size_t iov_len; +}; + +enum iter_type { + /* iter types */ + ITER_IOVEC, + ITER_KVEC, + ITER_BVEC, + ITER_XARRAY, + ITER_DISCARD, + ITER_UBUF, +}; + +#define ITER_SOURCE 1 // == WRITE +#define ITER_DEST 0 // == READ + +struct iov_iter_state { + size_t iov_offset; + size_t count; + unsigned long nr_segs; +}; + +struct iov_iter { + u8 iter_type; + bool copy_mc; + bool nofault; + bool data_source; + bool user_backed; + union { + size_t iov_offset; + int last_offset; + }; + /* + * Hack alert: overlay ubuf_iovec with iovec + count, so + * that the members resolve correctly regardless of the type + * of iterator used. This means that you can use: + * + * &iter->__ubuf_iovec or iter->__iov + * + * interchangably for the user_backed cases, hence simplifying + * some of the cases that need to deal with both. + */ + union { + /* + * This really should be a const, but we cannot do that without + * also modifying any of the zero-filling iter init functions. + * Leave it non-const for now, but it should be treated as such. + */ + struct iovec __ubuf_iovec; + struct { + union { + /* use iter_iov() to get the current vec */ + const struct iovec *__iov; + const struct kvec *kvec; + const struct bio_vec *bvec; + struct xarray *xarray; + void __user *ubuf; + }; + size_t count; + }; + }; + union { + unsigned long nr_segs; + loff_t xarray_start; + }; +}; + +static inline const struct iovec *iter_iov(const struct iov_iter *iter) +{ + if (iter->iter_type == ITER_UBUF) + return (const struct iovec *) &iter->__ubuf_iovec; + return iter->__iov; +} + +#define iter_iov_addr(iter) (iter_iov(iter)->iov_base + (iter)->iov_offset) +#define iter_iov_len(iter) (iter_iov(iter)->iov_len - (iter)->iov_offset) + +static inline enum iter_type iov_iter_type(const struct iov_iter *i) +{ + return i->iter_type; +} + +static inline void iov_iter_save_state(struct iov_iter *iter, + struct iov_iter_state *state) +{ + state->iov_offset = iter->iov_offset; + state->count = iter->count; + state->nr_segs = iter->nr_segs; +} + +static inline bool iter_is_ubuf(const struct iov_iter *i) +{ + return iov_iter_type(i) == ITER_UBUF; +} + +static inline bool iter_is_iovec(const struct iov_iter *i) +{ + return iov_iter_type(i) == ITER_IOVEC; +} + +static inline bool iov_iter_is_kvec(const struct iov_iter *i) +{ + return iov_iter_type(i) == ITER_KVEC; +} + +static inline bool iov_iter_is_bvec(const struct iov_iter *i) +{ + return iov_iter_type(i) == ITER_BVEC; +} + +static inline bool iov_iter_is_discard(const struct iov_iter *i) +{ + return iov_iter_type(i) == ITER_DISCARD; +} + +static inline bool iov_iter_is_xarray(const struct iov_iter *i) +{ + return iov_iter_type(i) == ITER_XARRAY; +} + +static inline unsigned char iov_iter_rw(const struct iov_iter *i) +{ + return i->data_source ? WRITE : READ; +} + +static inline bool user_backed_iter(const struct iov_iter *i) +{ + return i->user_backed; +} + +/* + * Total number of bytes covered by an iovec. + * + * NOTE that it is not safe to use this function until all the iovec's + * segment lengths have been validated. Because the individual lengths can + * overflow a size_t when added together. + */ +static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs) +{ + unsigned long seg; + size_t ret = 0; + + for (seg = 0; seg < nr_segs; seg++) + ret += iov[seg].iov_len; + return ret; +} + +size_t copy_page_from_iter_atomic(struct page *page, size_t offset, + size_t bytes, struct iov_iter *i); +void iov_iter_advance(struct iov_iter *i, size_t bytes); +void iov_iter_revert(struct iov_iter *i, size_t bytes); +size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t bytes); +size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t bytes); +size_t iov_iter_single_seg_count(const struct iov_iter *i); +size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, + struct iov_iter *i); +size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes, + struct iov_iter *i); + +size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i); +size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i); +size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i); + +static inline size_t copy_folio_to_iter(struct folio *folio, size_t offset, + size_t bytes, struct iov_iter *i) +{ + return copy_page_to_iter(&folio->page, offset, bytes, i); +} + +static inline size_t copy_folio_from_iter_atomic(struct folio *folio, + size_t offset, size_t bytes, struct iov_iter *i) +{ + return copy_page_from_iter_atomic(&folio->page, offset, bytes, i); +} + +size_t copy_page_to_iter_nofault(struct page *page, unsigned offset, + size_t bytes, struct iov_iter *i); + +static __always_inline __must_check +size_t copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i) +{ + if (check_copy_size(addr, bytes, true)) + return _copy_to_iter(addr, bytes, i); + return 0; +} + +static __always_inline __must_check +size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i) +{ + if (check_copy_size(addr, bytes, false)) + return _copy_from_iter(addr, bytes, i); + return 0; +} + +static __always_inline __must_check +bool copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i) +{ + size_t copied = copy_from_iter(addr, bytes, i); + if (likely(copied == bytes)) + return true; + iov_iter_revert(i, copied); + return false; +} + +static __always_inline __must_check +size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i) +{ + if (check_copy_size(addr, bytes, false)) + return _copy_from_iter_nocache(addr, bytes, i); + return 0; +} + +static __always_inline __must_check +bool copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i) +{ + size_t copied = copy_from_iter_nocache(addr, bytes, i); + if (likely(copied == bytes)) + return true; + iov_iter_revert(i, copied); + return false; +} + +#ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE +/* + * Note, users like pmem that depend on the stricter semantics of + * _copy_from_iter_flushcache() than _copy_from_iter_nocache() must check for + * IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) before assuming that the + * destination is flushed from the cache on return. + */ +size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i); +#else +#define _copy_from_iter_flushcache _copy_from_iter_nocache +#endif + +#ifdef CONFIG_ARCH_HAS_COPY_MC +size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i); +static inline void iov_iter_set_copy_mc(struct iov_iter *i) +{ + i->copy_mc = true; +} + +static inline bool iov_iter_is_copy_mc(const struct iov_iter *i) +{ + return i->copy_mc; +} +#else +#define _copy_mc_to_iter _copy_to_iter +static inline void iov_iter_set_copy_mc(struct iov_iter *i) { } +static inline bool iov_iter_is_copy_mc(const struct iov_iter *i) +{ + return false; +} +#endif + +size_t iov_iter_zero(size_t bytes, struct iov_iter *); +bool iov_iter_is_aligned(const struct iov_iter *i, unsigned addr_mask, + unsigned len_mask); +unsigned long iov_iter_alignment(const struct iov_iter *i); +unsigned long iov_iter_gap_alignment(const struct iov_iter *i); +void iov_iter_init(struct iov_iter *i, unsigned int direction, const struct iovec *iov, + unsigned long nr_segs, size_t count); +void iov_iter_kvec(struct iov_iter *i, unsigned int direction, const struct kvec *kvec, + unsigned long nr_segs, size_t count); +void iov_iter_bvec(struct iov_iter *i, unsigned int direction, const struct bio_vec *bvec, + unsigned long nr_segs, size_t count); +void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count); +void iov_iter_xarray(struct iov_iter *i, unsigned int direction, struct xarray *xarray, + loff_t start, size_t count); +ssize_t iov_iter_get_pages2(struct iov_iter *i, struct page **pages, + size_t maxsize, unsigned maxpages, size_t *start); +ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i, struct page ***pages, + size_t maxsize, size_t *start); +int iov_iter_npages(const struct iov_iter *i, int maxpages); +void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state); + +const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags); + +static inline size_t iov_iter_count(const struct iov_iter *i) +{ + return i->count; +} + +/* + * Cap the iov_iter by given limit; note that the second argument is + * *not* the new size - it's upper limit for such. Passing it a value + * greater than the amount of data in iov_iter is fine - it'll just do + * nothing in that case. + */ +static inline void iov_iter_truncate(struct iov_iter *i, u64 count) +{ + /* + * count doesn't have to fit in size_t - comparison extends both + * operands to u64 here and any value that would be truncated by + * conversion in assignement is by definition greater than all + * values of size_t, including old i->count. + */ + if (i->count > count) + i->count = count; +} + +/* + * reexpand a previously truncated iterator; count must be no more than how much + * we had shrunk it. + */ +static inline void iov_iter_reexpand(struct iov_iter *i, size_t count) +{ + i->count = count; +} + +static inline int +iov_iter_npages_cap(struct iov_iter *i, int maxpages, size_t max_bytes) +{ + size_t shorted = 0; + int npages; + + if (iov_iter_count(i) > max_bytes) { + shorted = iov_iter_count(i) - max_bytes; + iov_iter_truncate(i, max_bytes); + } + npages = iov_iter_npages(i, maxpages); + if (shorted) + iov_iter_reexpand(i, iov_iter_count(i) + shorted); + + return npages; +} + +struct csum_state { + __wsum csum; + size_t off; +}; + +size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *csstate, struct iov_iter *i); +size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i); + +static __always_inline __must_check +bool csum_and_copy_from_iter_full(void *addr, size_t bytes, + __wsum *csum, struct iov_iter *i) +{ + size_t copied = csum_and_copy_from_iter(addr, bytes, csum, i); + if (likely(copied == bytes)) + return true; + iov_iter_revert(i, copied); + return false; +} +size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp, + struct iov_iter *i); + +struct iovec *iovec_from_user(const struct iovec __user *uvector, + unsigned long nr_segs, unsigned long fast_segs, + struct iovec *fast_iov, bool compat); +ssize_t import_iovec(int type, const struct iovec __user *uvec, + unsigned nr_segs, unsigned fast_segs, struct iovec **iovp, + struct iov_iter *i); +ssize_t __import_iovec(int type, const struct iovec __user *uvec, + unsigned nr_segs, unsigned fast_segs, struct iovec **iovp, + struct iov_iter *i, bool compat); +int import_single_range(int type, void __user *buf, size_t len, + struct iovec *iov, struct iov_iter *i); +int import_ubuf(int type, void __user *buf, size_t len, struct iov_iter *i); + +static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction, + void __user *buf, size_t count) +{ + WARN_ON(direction & ~(READ | WRITE)); + *i = (struct iov_iter) { + .iter_type = ITER_UBUF, + .copy_mc = false, + .user_backed = true, + .data_source = direction, + .ubuf = buf, + .count = count, + .nr_segs = 1 + }; +} +/* Flags for iov_iter_get/extract_pages*() */ +/* Allow P2PDMA on the extracted pages */ +#define ITER_ALLOW_P2PDMA ((__force iov_iter_extraction_t)0x01) + +ssize_t iov_iter_extract_pages(struct iov_iter *i, struct page ***pages, + size_t maxsize, unsigned int maxpages, + iov_iter_extraction_t extraction_flags, + size_t *offset0); + +/** + * iov_iter_extract_will_pin - Indicate how pages from the iterator will be retained + * @iter: The iterator + * + * Examine the iterator and indicate by returning true or false as to how, if + * at all, pages extracted from the iterator will be retained by the extraction + * function. + * + * %true indicates that the pages will have a pin placed in them that the + * caller must unpin. This is must be done for DMA/async DIO to force fork() + * to forcibly copy a page for the child (the parent must retain the original + * page). + * + * %false indicates that no measures are taken and that it's up to the caller + * to retain the pages. + */ +static inline bool iov_iter_extract_will_pin(const struct iov_iter *iter) +{ + return user_backed_iter(iter); +} + +struct sg_table; +ssize_t extract_iter_to_sg(struct iov_iter *iter, size_t len, + struct sg_table *sgtable, unsigned int sg_max, + iov_iter_extraction_t extraction_flags); + +#endif |