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/* 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_UBUF,
ITER_IOVEC,
ITER_BVEC,
ITER_KVEC,
ITER_XARRAY,
ITER_DISCARD,
};
#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 nofault;
bool data_source;
size_t iov_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 iter_is_ubuf(i) || iter_is_iovec(i);
}
/*
* 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);
#else
#define _copy_mc_to_iter _copy_to_iter
#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 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_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,
.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
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