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