linux-stable/lib/iov_iter.c
Linus Torvalds 7a7fd0de4a Merge branch 'kmap-conversion-for-5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull kmap conversion updates from David Sterba:
 "This contains changes regarding kmap API use and eg conversion from
  kmap_atomic to kmap_local_page.

  The API belongs to memory management but to save cross-tree
  dependency headaches we've agreed to take it through the btrfs tree
  because there are some trivial conversions possible, while the rest
  will need some time and getting the easy cases out of the way would be
  convenient.

  The changes can be grouped:

   - function exports, new helpers

   - new VM_BUG_ON for additional verification; it's been discussed if
     it should be VM_BUG_ON or BUG_ON, the former was chosen due to
     performance reasons

   - code replaced by relevant helpers"

[ This is an updated version of a request that originally came in during
  the merge window, but I asked for some updates:

    https://lore.kernel.org/lkml/cover.1614090658.git.dsterba@suse.com/

  which is why this got merge after the merge window closed.  - Linus ]

* 'kmap-conversion-for-5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: use copy_highpage() instead of 2 kmaps()
  btrfs: use memcpy_[to|from]_page() and kmap_local_page()
  mm/highmem: Add VM_BUG_ON() to mem*_page() calls
  mm/highmem: Introduce memcpy_page(), memmove_page(), and memset_page()
  mm/highmem: Convert memcpy_[to|from]_page() to kmap_local_page()
  mm/highmem: Lift memcpy_[to|from]_page to core
2021-03-01 11:24:18 -08:00

1856 lines
44 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
#include <crypto/hash.h>
#include <linux/export.h>
#include <linux/bvec.h>
#include <linux/fault-inject-usercopy.h>
#include <linux/uio.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/splice.h>
#include <linux/compat.h>
#include <net/checksum.h>
#include <linux/scatterlist.h>
#include <linux/instrumented.h>
#define PIPE_PARANOIA /* for now */
#define iterate_iovec(i, n, __v, __p, skip, STEP) { \
size_t left; \
size_t wanted = n; \
__p = i->iov; \
__v.iov_len = min(n, __p->iov_len - skip); \
if (likely(__v.iov_len)) { \
__v.iov_base = __p->iov_base + skip; \
left = (STEP); \
__v.iov_len -= left; \
skip += __v.iov_len; \
n -= __v.iov_len; \
} else { \
left = 0; \
} \
while (unlikely(!left && n)) { \
__p++; \
__v.iov_len = min(n, __p->iov_len); \
if (unlikely(!__v.iov_len)) \
continue; \
__v.iov_base = __p->iov_base; \
left = (STEP); \
__v.iov_len -= left; \
skip = __v.iov_len; \
n -= __v.iov_len; \
} \
n = wanted - n; \
}
#define iterate_kvec(i, n, __v, __p, skip, STEP) { \
size_t wanted = n; \
__p = i->kvec; \
__v.iov_len = min(n, __p->iov_len - skip); \
if (likely(__v.iov_len)) { \
__v.iov_base = __p->iov_base + skip; \
(void)(STEP); \
skip += __v.iov_len; \
n -= __v.iov_len; \
} \
while (unlikely(n)) { \
__p++; \
__v.iov_len = min(n, __p->iov_len); \
if (unlikely(!__v.iov_len)) \
continue; \
__v.iov_base = __p->iov_base; \
(void)(STEP); \
skip = __v.iov_len; \
n -= __v.iov_len; \
} \
n = wanted; \
}
#define iterate_bvec(i, n, __v, __bi, skip, STEP) { \
struct bvec_iter __start; \
__start.bi_size = n; \
__start.bi_bvec_done = skip; \
__start.bi_idx = 0; \
for_each_bvec(__v, i->bvec, __bi, __start) { \
(void)(STEP); \
} \
}
#define iterate_all_kinds(i, n, v, I, B, K) { \
if (likely(n)) { \
size_t skip = i->iov_offset; \
if (unlikely(i->type & ITER_BVEC)) { \
struct bio_vec v; \
struct bvec_iter __bi; \
iterate_bvec(i, n, v, __bi, skip, (B)) \
} else if (unlikely(i->type & ITER_KVEC)) { \
const struct kvec *kvec; \
struct kvec v; \
iterate_kvec(i, n, v, kvec, skip, (K)) \
} else if (unlikely(i->type & ITER_DISCARD)) { \
} else { \
const struct iovec *iov; \
struct iovec v; \
iterate_iovec(i, n, v, iov, skip, (I)) \
} \
} \
}
#define iterate_and_advance(i, n, v, I, B, K) { \
if (unlikely(i->count < n)) \
n = i->count; \
if (i->count) { \
size_t skip = i->iov_offset; \
if (unlikely(i->type & ITER_BVEC)) { \
const struct bio_vec *bvec = i->bvec; \
struct bio_vec v; \
struct bvec_iter __bi; \
iterate_bvec(i, n, v, __bi, skip, (B)) \
i->bvec = __bvec_iter_bvec(i->bvec, __bi); \
i->nr_segs -= i->bvec - bvec; \
skip = __bi.bi_bvec_done; \
} else if (unlikely(i->type & ITER_KVEC)) { \
const struct kvec *kvec; \
struct kvec v; \
iterate_kvec(i, n, v, kvec, skip, (K)) \
if (skip == kvec->iov_len) { \
kvec++; \
skip = 0; \
} \
i->nr_segs -= kvec - i->kvec; \
i->kvec = kvec; \
} else if (unlikely(i->type & ITER_DISCARD)) { \
skip += n; \
} else { \
const struct iovec *iov; \
struct iovec v; \
iterate_iovec(i, n, v, iov, skip, (I)) \
if (skip == iov->iov_len) { \
iov++; \
skip = 0; \
} \
i->nr_segs -= iov - i->iov; \
i->iov = iov; \
} \
i->count -= n; \
i->iov_offset = skip; \
} \
}
static int copyout(void __user *to, const void *from, size_t n)
{
if (should_fail_usercopy())
return n;
if (access_ok(to, n)) {
instrument_copy_to_user(to, from, n);
n = raw_copy_to_user(to, from, n);
}
return n;
}
static int copyin(void *to, const void __user *from, size_t n)
{
if (should_fail_usercopy())
return n;
if (access_ok(from, n)) {
instrument_copy_from_user(to, from, n);
n = raw_copy_from_user(to, from, n);
}
return n;
}
static size_t copy_page_to_iter_iovec(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i)
{
size_t skip, copy, left, wanted;
const struct iovec *iov;
char __user *buf;
void *kaddr, *from;
if (unlikely(bytes > i->count))
bytes = i->count;
if (unlikely(!bytes))
return 0;
might_fault();
wanted = bytes;
iov = i->iov;
skip = i->iov_offset;
buf = iov->iov_base + skip;
copy = min(bytes, iov->iov_len - skip);
if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_pages_writeable(buf, copy)) {
kaddr = kmap_atomic(page);
from = kaddr + offset;
/* first chunk, usually the only one */
left = copyout(buf, from, copy);
copy -= left;
skip += copy;
from += copy;
bytes -= copy;
while (unlikely(!left && bytes)) {
iov++;
buf = iov->iov_base;
copy = min(bytes, iov->iov_len);
left = copyout(buf, from, copy);
copy -= left;
skip = copy;
from += copy;
bytes -= copy;
}
if (likely(!bytes)) {
kunmap_atomic(kaddr);
goto done;
}
offset = from - kaddr;
buf += copy;
kunmap_atomic(kaddr);
copy = min(bytes, iov->iov_len - skip);
}
/* Too bad - revert to non-atomic kmap */
kaddr = kmap(page);
from = kaddr + offset;
left = copyout(buf, from, copy);
copy -= left;
skip += copy;
from += copy;
bytes -= copy;
while (unlikely(!left && bytes)) {
iov++;
buf = iov->iov_base;
copy = min(bytes, iov->iov_len);
left = copyout(buf, from, copy);
copy -= left;
skip = copy;
from += copy;
bytes -= copy;
}
kunmap(page);
done:
if (skip == iov->iov_len) {
iov++;
skip = 0;
}
i->count -= wanted - bytes;
i->nr_segs -= iov - i->iov;
i->iov = iov;
i->iov_offset = skip;
return wanted - bytes;
}
static size_t copy_page_from_iter_iovec(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i)
{
size_t skip, copy, left, wanted;
const struct iovec *iov;
char __user *buf;
void *kaddr, *to;
if (unlikely(bytes > i->count))
bytes = i->count;
if (unlikely(!bytes))
return 0;
might_fault();
wanted = bytes;
iov = i->iov;
skip = i->iov_offset;
buf = iov->iov_base + skip;
copy = min(bytes, iov->iov_len - skip);
if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_pages_readable(buf, copy)) {
kaddr = kmap_atomic(page);
to = kaddr + offset;
/* first chunk, usually the only one */
left = copyin(to, buf, copy);
copy -= left;
skip += copy;
to += copy;
bytes -= copy;
while (unlikely(!left && bytes)) {
iov++;
buf = iov->iov_base;
copy = min(bytes, iov->iov_len);
left = copyin(to, buf, copy);
copy -= left;
skip = copy;
to += copy;
bytes -= copy;
}
if (likely(!bytes)) {
kunmap_atomic(kaddr);
goto done;
}
offset = to - kaddr;
buf += copy;
kunmap_atomic(kaddr);
copy = min(bytes, iov->iov_len - skip);
}
/* Too bad - revert to non-atomic kmap */
kaddr = kmap(page);
to = kaddr + offset;
left = copyin(to, buf, copy);
copy -= left;
skip += copy;
to += copy;
bytes -= copy;
while (unlikely(!left && bytes)) {
iov++;
buf = iov->iov_base;
copy = min(bytes, iov->iov_len);
left = copyin(to, buf, copy);
copy -= left;
skip = copy;
to += copy;
bytes -= copy;
}
kunmap(page);
done:
if (skip == iov->iov_len) {
iov++;
skip = 0;
}
i->count -= wanted - bytes;
i->nr_segs -= iov - i->iov;
i->iov = iov;
i->iov_offset = skip;
return wanted - bytes;
}
#ifdef PIPE_PARANOIA
static bool sanity(const struct iov_iter *i)
{
struct pipe_inode_info *pipe = i->pipe;
unsigned int p_head = pipe->head;
unsigned int p_tail = pipe->tail;
unsigned int p_mask = pipe->ring_size - 1;
unsigned int p_occupancy = pipe_occupancy(p_head, p_tail);
unsigned int i_head = i->head;
unsigned int idx;
if (i->iov_offset) {
struct pipe_buffer *p;
if (unlikely(p_occupancy == 0))
goto Bad; // pipe must be non-empty
if (unlikely(i_head != p_head - 1))
goto Bad; // must be at the last buffer...
p = &pipe->bufs[i_head & p_mask];
if (unlikely(p->offset + p->len != i->iov_offset))
goto Bad; // ... at the end of segment
} else {
if (i_head != p_head)
goto Bad; // must be right after the last buffer
}
return true;
Bad:
printk(KERN_ERR "idx = %d, offset = %zd\n", i_head, i->iov_offset);
printk(KERN_ERR "head = %d, tail = %d, buffers = %d\n",
p_head, p_tail, pipe->ring_size);
for (idx = 0; idx < pipe->ring_size; idx++)
printk(KERN_ERR "[%p %p %d %d]\n",
pipe->bufs[idx].ops,
pipe->bufs[idx].page,
pipe->bufs[idx].offset,
pipe->bufs[idx].len);
WARN_ON(1);
return false;
}
#else
#define sanity(i) true
#endif
static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i)
{
struct pipe_inode_info *pipe = i->pipe;
struct pipe_buffer *buf;
unsigned int p_tail = pipe->tail;
unsigned int p_mask = pipe->ring_size - 1;
unsigned int i_head = i->head;
size_t off;
if (unlikely(bytes > i->count))
bytes = i->count;
if (unlikely(!bytes))
return 0;
if (!sanity(i))
return 0;
off = i->iov_offset;
buf = &pipe->bufs[i_head & p_mask];
if (off) {
if (offset == off && buf->page == page) {
/* merge with the last one */
buf->len += bytes;
i->iov_offset += bytes;
goto out;
}
i_head++;
buf = &pipe->bufs[i_head & p_mask];
}
if (pipe_full(i_head, p_tail, pipe->max_usage))
return 0;
buf->ops = &page_cache_pipe_buf_ops;
get_page(page);
buf->page = page;
buf->offset = offset;
buf->len = bytes;
pipe->head = i_head + 1;
i->iov_offset = offset + bytes;
i->head = i_head;
out:
i->count -= bytes;
return bytes;
}
/*
* Fault in one or more iovecs of the given iov_iter, to a maximum length of
* bytes. For each iovec, fault in each page that constitutes the iovec.
*
* Return 0 on success, or non-zero if the memory could not be accessed (i.e.
* because it is an invalid address).
*/
int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
{
size_t skip = i->iov_offset;
const struct iovec *iov;
int err;
struct iovec v;
if (!(i->type & (ITER_BVEC|ITER_KVEC))) {
iterate_iovec(i, bytes, v, iov, skip, ({
err = fault_in_pages_readable(v.iov_base, v.iov_len);
if (unlikely(err))
return err;
0;}))
}
return 0;
}
EXPORT_SYMBOL(iov_iter_fault_in_readable);
void iov_iter_init(struct iov_iter *i, unsigned int direction,
const struct iovec *iov, unsigned long nr_segs,
size_t count)
{
WARN_ON(direction & ~(READ | WRITE));
direction &= READ | WRITE;
/* It will get better. Eventually... */
if (uaccess_kernel()) {
i->type = ITER_KVEC | direction;
i->kvec = (struct kvec *)iov;
} else {
i->type = ITER_IOVEC | direction;
i->iov = iov;
}
i->nr_segs = nr_segs;
i->iov_offset = 0;
i->count = count;
}
EXPORT_SYMBOL(iov_iter_init);
static void memzero_page(struct page *page, size_t offset, size_t len)
{
char *addr = kmap_atomic(page);
memset(addr + offset, 0, len);
kunmap_atomic(addr);
}
static inline bool allocated(struct pipe_buffer *buf)
{
return buf->ops == &default_pipe_buf_ops;
}
static inline void data_start(const struct iov_iter *i,
unsigned int *iter_headp, size_t *offp)
{
unsigned int p_mask = i->pipe->ring_size - 1;
unsigned int iter_head = i->head;
size_t off = i->iov_offset;
if (off && (!allocated(&i->pipe->bufs[iter_head & p_mask]) ||
off == PAGE_SIZE)) {
iter_head++;
off = 0;
}
*iter_headp = iter_head;
*offp = off;
}
static size_t push_pipe(struct iov_iter *i, size_t size,
int *iter_headp, size_t *offp)
{
struct pipe_inode_info *pipe = i->pipe;
unsigned int p_tail = pipe->tail;
unsigned int p_mask = pipe->ring_size - 1;
unsigned int iter_head;
size_t off;
ssize_t left;
if (unlikely(size > i->count))
size = i->count;
if (unlikely(!size))
return 0;
left = size;
data_start(i, &iter_head, &off);
*iter_headp = iter_head;
*offp = off;
if (off) {
left -= PAGE_SIZE - off;
if (left <= 0) {
pipe->bufs[iter_head & p_mask].len += size;
return size;
}
pipe->bufs[iter_head & p_mask].len = PAGE_SIZE;
iter_head++;
}
while (!pipe_full(iter_head, p_tail, pipe->max_usage)) {
struct pipe_buffer *buf = &pipe->bufs[iter_head & p_mask];
struct page *page = alloc_page(GFP_USER);
if (!page)
break;
buf->ops = &default_pipe_buf_ops;
buf->page = page;
buf->offset = 0;
buf->len = min_t(ssize_t, left, PAGE_SIZE);
left -= buf->len;
iter_head++;
pipe->head = iter_head;
if (left == 0)
return size;
}
return size - left;
}
static size_t copy_pipe_to_iter(const void *addr, size_t bytes,
struct iov_iter *i)
{
struct pipe_inode_info *pipe = i->pipe;
unsigned int p_mask = pipe->ring_size - 1;
unsigned int i_head;
size_t n, off;
if (!sanity(i))
return 0;
bytes = n = push_pipe(i, bytes, &i_head, &off);
if (unlikely(!n))
return 0;
do {
size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
memcpy_to_page(pipe->bufs[i_head & p_mask].page, off, addr, chunk);
i->head = i_head;
i->iov_offset = off + chunk;
n -= chunk;
addr += chunk;
off = 0;
i_head++;
} while (n);
i->count -= bytes;
return bytes;
}
static __wsum csum_and_memcpy(void *to, const void *from, size_t len,
__wsum sum, size_t off)
{
__wsum next = csum_partial_copy_nocheck(from, to, len);
return csum_block_add(sum, next, off);
}
static size_t csum_and_copy_to_pipe_iter(const void *addr, size_t bytes,
struct csum_state *csstate,
struct iov_iter *i)
{
struct pipe_inode_info *pipe = i->pipe;
unsigned int p_mask = pipe->ring_size - 1;
__wsum sum = csstate->csum;
size_t off = csstate->off;
unsigned int i_head;
size_t n, r;
if (!sanity(i))
return 0;
bytes = n = push_pipe(i, bytes, &i_head, &r);
if (unlikely(!n))
return 0;
do {
size_t chunk = min_t(size_t, n, PAGE_SIZE - r);
char *p = kmap_atomic(pipe->bufs[i_head & p_mask].page);
sum = csum_and_memcpy(p + r, addr, chunk, sum, off);
kunmap_atomic(p);
i->head = i_head;
i->iov_offset = r + chunk;
n -= chunk;
off += chunk;
addr += chunk;
r = 0;
i_head++;
} while (n);
i->count -= bytes;
csstate->csum = sum;
csstate->off = off;
return bytes;
}
size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
{
const char *from = addr;
if (unlikely(iov_iter_is_pipe(i)))
return copy_pipe_to_iter(addr, bytes, i);
if (iter_is_iovec(i))
might_fault();
iterate_and_advance(i, bytes, v,
copyout(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len),
memcpy_to_page(v.bv_page, v.bv_offset,
(from += v.bv_len) - v.bv_len, v.bv_len),
memcpy(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len)
)
return bytes;
}
EXPORT_SYMBOL(_copy_to_iter);
#ifdef CONFIG_ARCH_HAS_COPY_MC
static int copyout_mc(void __user *to, const void *from, size_t n)
{
if (access_ok(to, n)) {
instrument_copy_to_user(to, from, n);
n = copy_mc_to_user((__force void *) to, from, n);
}
return n;
}
static unsigned long copy_mc_to_page(struct page *page, size_t offset,
const char *from, size_t len)
{
unsigned long ret;
char *to;
to = kmap_atomic(page);
ret = copy_mc_to_kernel(to + offset, from, len);
kunmap_atomic(to);
return ret;
}
static size_t copy_mc_pipe_to_iter(const void *addr, size_t bytes,
struct iov_iter *i)
{
struct pipe_inode_info *pipe = i->pipe;
unsigned int p_mask = pipe->ring_size - 1;
unsigned int i_head;
size_t n, off, xfer = 0;
if (!sanity(i))
return 0;
bytes = n = push_pipe(i, bytes, &i_head, &off);
if (unlikely(!n))
return 0;
do {
size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
unsigned long rem;
rem = copy_mc_to_page(pipe->bufs[i_head & p_mask].page,
off, addr, chunk);
i->head = i_head;
i->iov_offset = off + chunk - rem;
xfer += chunk - rem;
if (rem)
break;
n -= chunk;
addr += chunk;
off = 0;
i_head++;
} while (n);
i->count -= xfer;
return xfer;
}
/**
* _copy_mc_to_iter - copy to iter with source memory error exception handling
* @addr: source kernel address
* @bytes: total transfer length
* @iter: destination iterator
*
* The pmem driver deploys this for the dax operation
* (dax_copy_to_iter()) for dax reads (bypass page-cache and the
* block-layer). Upon #MC read(2) aborts and returns EIO or the bytes
* successfully copied.
*
* The main differences between this and typical _copy_to_iter().
*
* * Typical tail/residue handling after a fault retries the copy
* byte-by-byte until the fault happens again. Re-triggering machine
* checks is potentially fatal so the implementation uses source
* alignment and poison alignment assumptions to avoid re-triggering
* hardware exceptions.
*
* * ITER_KVEC, ITER_PIPE, and ITER_BVEC can return short copies.
* Compare to copy_to_iter() where only ITER_IOVEC attempts might return
* a short copy.
*/
size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
{
const char *from = addr;
unsigned long rem, curr_addr, s_addr = (unsigned long) addr;
if (unlikely(iov_iter_is_pipe(i)))
return copy_mc_pipe_to_iter(addr, bytes, i);
if (iter_is_iovec(i))
might_fault();
iterate_and_advance(i, bytes, v,
copyout_mc(v.iov_base, (from += v.iov_len) - v.iov_len,
v.iov_len),
({
rem = copy_mc_to_page(v.bv_page, v.bv_offset,
(from += v.bv_len) - v.bv_len, v.bv_len);
if (rem) {
curr_addr = (unsigned long) from;
bytes = curr_addr - s_addr - rem;
return bytes;
}
}),
({
rem = copy_mc_to_kernel(v.iov_base, (from += v.iov_len)
- v.iov_len, v.iov_len);
if (rem) {
curr_addr = (unsigned long) from;
bytes = curr_addr - s_addr - rem;
return bytes;
}
})
)
return bytes;
}
EXPORT_SYMBOL_GPL(_copy_mc_to_iter);
#endif /* CONFIG_ARCH_HAS_COPY_MC */
size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
{
char *to = addr;
if (unlikely(iov_iter_is_pipe(i))) {
WARN_ON(1);
return 0;
}
if (iter_is_iovec(i))
might_fault();
iterate_and_advance(i, bytes, v,
copyin((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len),
memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
v.bv_offset, v.bv_len),
memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
)
return bytes;
}
EXPORT_SYMBOL(_copy_from_iter);
bool _copy_from_iter_full(void *addr, size_t bytes, struct iov_iter *i)
{
char *to = addr;
if (unlikely(iov_iter_is_pipe(i))) {
WARN_ON(1);
return false;
}
if (unlikely(i->count < bytes))
return false;
if (iter_is_iovec(i))
might_fault();
iterate_all_kinds(i, bytes, v, ({
if (copyin((to += v.iov_len) - v.iov_len,
v.iov_base, v.iov_len))
return false;
0;}),
memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
v.bv_offset, v.bv_len),
memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
)
iov_iter_advance(i, bytes);
return true;
}
EXPORT_SYMBOL(_copy_from_iter_full);
size_t _copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i)
{
char *to = addr;
if (unlikely(iov_iter_is_pipe(i))) {
WARN_ON(1);
return 0;
}
iterate_and_advance(i, bytes, v,
__copy_from_user_inatomic_nocache((to += v.iov_len) - v.iov_len,
v.iov_base, v.iov_len),
memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
v.bv_offset, v.bv_len),
memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
)
return bytes;
}
EXPORT_SYMBOL(_copy_from_iter_nocache);
#ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
/**
* _copy_from_iter_flushcache - write destination through cpu cache
* @addr: destination kernel address
* @bytes: total transfer length
* @iter: source iterator
*
* The pmem driver arranges for filesystem-dax to use this facility via
* dax_copy_from_iter() for ensuring that writes to persistent memory
* are flushed through the CPU cache. It is differentiated from
* _copy_from_iter_nocache() in that guarantees all data is flushed for
* all iterator types. The _copy_from_iter_nocache() only attempts to
* bypass the cache for the ITER_IOVEC case, and on some archs may use
* instructions that strand dirty-data in the cache.
*/
size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
{
char *to = addr;
if (unlikely(iov_iter_is_pipe(i))) {
WARN_ON(1);
return 0;
}
iterate_and_advance(i, bytes, v,
__copy_from_user_flushcache((to += v.iov_len) - v.iov_len,
v.iov_base, v.iov_len),
memcpy_page_flushcache((to += v.bv_len) - v.bv_len, v.bv_page,
v.bv_offset, v.bv_len),
memcpy_flushcache((to += v.iov_len) - v.iov_len, v.iov_base,
v.iov_len)
)
return bytes;
}
EXPORT_SYMBOL_GPL(_copy_from_iter_flushcache);
#endif
bool _copy_from_iter_full_nocache(void *addr, size_t bytes, struct iov_iter *i)
{
char *to = addr;
if (unlikely(iov_iter_is_pipe(i))) {
WARN_ON(1);
return false;
}
if (unlikely(i->count < bytes))
return false;
iterate_all_kinds(i, bytes, v, ({
if (__copy_from_user_inatomic_nocache((to += v.iov_len) - v.iov_len,
v.iov_base, v.iov_len))
return false;
0;}),
memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
v.bv_offset, v.bv_len),
memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
)
iov_iter_advance(i, bytes);
return true;
}
EXPORT_SYMBOL(_copy_from_iter_full_nocache);
static inline bool page_copy_sane(struct page *page, size_t offset, size_t n)
{
struct page *head;
size_t v = n + offset;
/*
* The general case needs to access the page order in order
* to compute the page size.
* However, we mostly deal with order-0 pages and thus can
* avoid a possible cache line miss for requests that fit all
* page orders.
*/
if (n <= v && v <= PAGE_SIZE)
return true;
head = compound_head(page);
v += (page - head) << PAGE_SHIFT;
if (likely(n <= v && v <= (page_size(head))))
return true;
WARN_ON(1);
return false;
}
size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i)
{
if (unlikely(!page_copy_sane(page, offset, bytes)))
return 0;
if (i->type & (ITER_BVEC|ITER_KVEC)) {
void *kaddr = kmap_atomic(page);
size_t wanted = copy_to_iter(kaddr + offset, bytes, i);
kunmap_atomic(kaddr);
return wanted;
} else if (unlikely(iov_iter_is_discard(i)))
return bytes;
else if (likely(!iov_iter_is_pipe(i)))
return copy_page_to_iter_iovec(page, offset, bytes, i);
else
return copy_page_to_iter_pipe(page, offset, bytes, i);
}
EXPORT_SYMBOL(copy_page_to_iter);
size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i)
{
if (unlikely(!page_copy_sane(page, offset, bytes)))
return 0;
if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
WARN_ON(1);
return 0;
}
if (i->type & (ITER_BVEC|ITER_KVEC)) {
void *kaddr = kmap_atomic(page);
size_t wanted = _copy_from_iter(kaddr + offset, bytes, i);
kunmap_atomic(kaddr);
return wanted;
} else
return copy_page_from_iter_iovec(page, offset, bytes, i);
}
EXPORT_SYMBOL(copy_page_from_iter);
static size_t pipe_zero(size_t bytes, struct iov_iter *i)
{
struct pipe_inode_info *pipe = i->pipe;
unsigned int p_mask = pipe->ring_size - 1;
unsigned int i_head;
size_t n, off;
if (!sanity(i))
return 0;
bytes = n = push_pipe(i, bytes, &i_head, &off);
if (unlikely(!n))
return 0;
do {
size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
memzero_page(pipe->bufs[i_head & p_mask].page, off, chunk);
i->head = i_head;
i->iov_offset = off + chunk;
n -= chunk;
off = 0;
i_head++;
} while (n);
i->count -= bytes;
return bytes;
}
size_t iov_iter_zero(size_t bytes, struct iov_iter *i)
{
if (unlikely(iov_iter_is_pipe(i)))
return pipe_zero(bytes, i);
iterate_and_advance(i, bytes, v,
clear_user(v.iov_base, v.iov_len),
memzero_page(v.bv_page, v.bv_offset, v.bv_len),
memset(v.iov_base, 0, v.iov_len)
)
return bytes;
}
EXPORT_SYMBOL(iov_iter_zero);
size_t iov_iter_copy_from_user_atomic(struct page *page,
struct iov_iter *i, unsigned long offset, size_t bytes)
{
char *kaddr = kmap_atomic(page), *p = kaddr + offset;
if (unlikely(!page_copy_sane(page, offset, bytes))) {
kunmap_atomic(kaddr);
return 0;
}
if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
kunmap_atomic(kaddr);
WARN_ON(1);
return 0;
}
iterate_all_kinds(i, bytes, v,
copyin((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len),
memcpy_from_page((p += v.bv_len) - v.bv_len, v.bv_page,
v.bv_offset, v.bv_len),
memcpy((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
)
kunmap_atomic(kaddr);
return bytes;
}
EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
static inline void pipe_truncate(struct iov_iter *i)
{
struct pipe_inode_info *pipe = i->pipe;
unsigned int p_tail = pipe->tail;
unsigned int p_head = pipe->head;
unsigned int p_mask = pipe->ring_size - 1;
if (!pipe_empty(p_head, p_tail)) {
struct pipe_buffer *buf;
unsigned int i_head = i->head;
size_t off = i->iov_offset;
if (off) {
buf = &pipe->bufs[i_head & p_mask];
buf->len = off - buf->offset;
i_head++;
}
while (p_head != i_head) {
p_head--;
pipe_buf_release(pipe, &pipe->bufs[p_head & p_mask]);
}
pipe->head = p_head;
}
}
static void pipe_advance(struct iov_iter *i, size_t size)
{
struct pipe_inode_info *pipe = i->pipe;
if (unlikely(i->count < size))
size = i->count;
if (size) {
struct pipe_buffer *buf;
unsigned int p_mask = pipe->ring_size - 1;
unsigned int i_head = i->head;
size_t off = i->iov_offset, left = size;
if (off) /* make it relative to the beginning of buffer */
left += off - pipe->bufs[i_head & p_mask].offset;
while (1) {
buf = &pipe->bufs[i_head & p_mask];
if (left <= buf->len)
break;
left -= buf->len;
i_head++;
}
i->head = i_head;
i->iov_offset = buf->offset + left;
}
i->count -= size;
/* ... and discard everything past that point */
pipe_truncate(i);
}
static void iov_iter_bvec_advance(struct iov_iter *i, size_t size)
{
struct bvec_iter bi;
bi.bi_size = i->count;
bi.bi_bvec_done = i->iov_offset;
bi.bi_idx = 0;
bvec_iter_advance(i->bvec, &bi, size);
i->bvec += bi.bi_idx;
i->nr_segs -= bi.bi_idx;
i->count = bi.bi_size;
i->iov_offset = bi.bi_bvec_done;
}
void iov_iter_advance(struct iov_iter *i, size_t size)
{
if (unlikely(iov_iter_is_pipe(i))) {
pipe_advance(i, size);
return;
}
if (unlikely(iov_iter_is_discard(i))) {
i->count -= size;
return;
}
if (iov_iter_is_bvec(i)) {
iov_iter_bvec_advance(i, size);
return;
}
iterate_and_advance(i, size, v, 0, 0, 0)
}
EXPORT_SYMBOL(iov_iter_advance);
void iov_iter_revert(struct iov_iter *i, size_t unroll)
{
if (!unroll)
return;
if (WARN_ON(unroll > MAX_RW_COUNT))
return;
i->count += unroll;
if (unlikely(iov_iter_is_pipe(i))) {
struct pipe_inode_info *pipe = i->pipe;
unsigned int p_mask = pipe->ring_size - 1;
unsigned int i_head = i->head;
size_t off = i->iov_offset;
while (1) {
struct pipe_buffer *b = &pipe->bufs[i_head & p_mask];
size_t n = off - b->offset;
if (unroll < n) {
off -= unroll;
break;
}
unroll -= n;
if (!unroll && i_head == i->start_head) {
off = 0;
break;
}
i_head--;
b = &pipe->bufs[i_head & p_mask];
off = b->offset + b->len;
}
i->iov_offset = off;
i->head = i_head;
pipe_truncate(i);
return;
}
if (unlikely(iov_iter_is_discard(i)))
return;
if (unroll <= i->iov_offset) {
i->iov_offset -= unroll;
return;
}
unroll -= i->iov_offset;
if (iov_iter_is_bvec(i)) {
const struct bio_vec *bvec = i->bvec;
while (1) {
size_t n = (--bvec)->bv_len;
i->nr_segs++;
if (unroll <= n) {
i->bvec = bvec;
i->iov_offset = n - unroll;
return;
}
unroll -= n;
}
} else { /* same logics for iovec and kvec */
const struct iovec *iov = i->iov;
while (1) {
size_t n = (--iov)->iov_len;
i->nr_segs++;
if (unroll <= n) {
i->iov = iov;
i->iov_offset = n - unroll;
return;
}
unroll -= n;
}
}
}
EXPORT_SYMBOL(iov_iter_revert);
/*
* Return the count of just the current iov_iter segment.
*/
size_t iov_iter_single_seg_count(const struct iov_iter *i)
{
if (unlikely(iov_iter_is_pipe(i)))
return i->count; // it is a silly place, anyway
if (i->nr_segs == 1)
return i->count;
if (unlikely(iov_iter_is_discard(i)))
return i->count;
else if (iov_iter_is_bvec(i))
return min(i->count, i->bvec->bv_len - i->iov_offset);
else
return min(i->count, i->iov->iov_len - i->iov_offset);
}
EXPORT_SYMBOL(iov_iter_single_seg_count);
void iov_iter_kvec(struct iov_iter *i, unsigned int direction,
const struct kvec *kvec, unsigned long nr_segs,
size_t count)
{
WARN_ON(direction & ~(READ | WRITE));
i->type = ITER_KVEC | (direction & (READ | WRITE));
i->kvec = kvec;
i->nr_segs = nr_segs;
i->iov_offset = 0;
i->count = count;
}
EXPORT_SYMBOL(iov_iter_kvec);
void iov_iter_bvec(struct iov_iter *i, unsigned int direction,
const struct bio_vec *bvec, unsigned long nr_segs,
size_t count)
{
WARN_ON(direction & ~(READ | WRITE));
i->type = ITER_BVEC | (direction & (READ | WRITE));
i->bvec = bvec;
i->nr_segs = nr_segs;
i->iov_offset = 0;
i->count = count;
}
EXPORT_SYMBOL(iov_iter_bvec);
void iov_iter_pipe(struct iov_iter *i, unsigned int direction,
struct pipe_inode_info *pipe,
size_t count)
{
BUG_ON(direction != READ);
WARN_ON(pipe_full(pipe->head, pipe->tail, pipe->ring_size));
i->type = ITER_PIPE | READ;
i->pipe = pipe;
i->head = pipe->head;
i->iov_offset = 0;
i->count = count;
i->start_head = i->head;
}
EXPORT_SYMBOL(iov_iter_pipe);
/**
* iov_iter_discard - Initialise an I/O iterator that discards data
* @i: The iterator to initialise.
* @direction: The direction of the transfer.
* @count: The size of the I/O buffer in bytes.
*
* Set up an I/O iterator that just discards everything that's written to it.
* It's only available as a READ iterator.
*/
void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count)
{
BUG_ON(direction != READ);
i->type = ITER_DISCARD | READ;
i->count = count;
i->iov_offset = 0;
}
EXPORT_SYMBOL(iov_iter_discard);
unsigned long iov_iter_alignment(const struct iov_iter *i)
{
unsigned long res = 0;
size_t size = i->count;
if (unlikely(iov_iter_is_pipe(i))) {
unsigned int p_mask = i->pipe->ring_size - 1;
if (size && i->iov_offset && allocated(&i->pipe->bufs[i->head & p_mask]))
return size | i->iov_offset;
return size;
}
iterate_all_kinds(i, size, v,
(res |= (unsigned long)v.iov_base | v.iov_len, 0),
res |= v.bv_offset | v.bv_len,
res |= (unsigned long)v.iov_base | v.iov_len
)
return res;
}
EXPORT_SYMBOL(iov_iter_alignment);
unsigned long iov_iter_gap_alignment(const struct iov_iter *i)
{
unsigned long res = 0;
size_t size = i->count;
if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
WARN_ON(1);
return ~0U;
}
iterate_all_kinds(i, size, v,
(res |= (!res ? 0 : (unsigned long)v.iov_base) |
(size != v.iov_len ? size : 0), 0),
(res |= (!res ? 0 : (unsigned long)v.bv_offset) |
(size != v.bv_len ? size : 0)),
(res |= (!res ? 0 : (unsigned long)v.iov_base) |
(size != v.iov_len ? size : 0))
);
return res;
}
EXPORT_SYMBOL(iov_iter_gap_alignment);
static inline ssize_t __pipe_get_pages(struct iov_iter *i,
size_t maxsize,
struct page **pages,
int iter_head,
size_t *start)
{
struct pipe_inode_info *pipe = i->pipe;
unsigned int p_mask = pipe->ring_size - 1;
ssize_t n = push_pipe(i, maxsize, &iter_head, start);
if (!n)
return -EFAULT;
maxsize = n;
n += *start;
while (n > 0) {
get_page(*pages++ = pipe->bufs[iter_head & p_mask].page);
iter_head++;
n -= PAGE_SIZE;
}
return maxsize;
}
static ssize_t pipe_get_pages(struct iov_iter *i,
struct page **pages, size_t maxsize, unsigned maxpages,
size_t *start)
{
unsigned int iter_head, npages;
size_t capacity;
if (!maxsize)
return 0;
if (!sanity(i))
return -EFAULT;
data_start(i, &iter_head, start);
/* Amount of free space: some of this one + all after this one */
npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe);
capacity = min(npages, maxpages) * PAGE_SIZE - *start;
return __pipe_get_pages(i, min(maxsize, capacity), pages, iter_head, start);
}
ssize_t iov_iter_get_pages(struct iov_iter *i,
struct page **pages, size_t maxsize, unsigned maxpages,
size_t *start)
{
if (maxsize > i->count)
maxsize = i->count;
if (unlikely(iov_iter_is_pipe(i)))
return pipe_get_pages(i, pages, maxsize, maxpages, start);
if (unlikely(iov_iter_is_discard(i)))
return -EFAULT;
iterate_all_kinds(i, maxsize, v, ({
unsigned long addr = (unsigned long)v.iov_base;
size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
int n;
int res;
if (len > maxpages * PAGE_SIZE)
len = maxpages * PAGE_SIZE;
addr &= ~(PAGE_SIZE - 1);
n = DIV_ROUND_UP(len, PAGE_SIZE);
res = get_user_pages_fast(addr, n,
iov_iter_rw(i) != WRITE ? FOLL_WRITE : 0,
pages);
if (unlikely(res < 0))
return res;
return (res == n ? len : res * PAGE_SIZE) - *start;
0;}),({
/* can't be more than PAGE_SIZE */
*start = v.bv_offset;
get_page(*pages = v.bv_page);
return v.bv_len;
}),({
return -EFAULT;
})
)
return 0;
}
EXPORT_SYMBOL(iov_iter_get_pages);
static struct page **get_pages_array(size_t n)
{
return kvmalloc_array(n, sizeof(struct page *), GFP_KERNEL);
}
static ssize_t pipe_get_pages_alloc(struct iov_iter *i,
struct page ***pages, size_t maxsize,
size_t *start)
{
struct page **p;
unsigned int iter_head, npages;
ssize_t n;
if (!maxsize)
return 0;
if (!sanity(i))
return -EFAULT;
data_start(i, &iter_head, start);
/* Amount of free space: some of this one + all after this one */
npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe);
n = npages * PAGE_SIZE - *start;
if (maxsize > n)
maxsize = n;
else
npages = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE);
p = get_pages_array(npages);
if (!p)
return -ENOMEM;
n = __pipe_get_pages(i, maxsize, p, iter_head, start);
if (n > 0)
*pages = p;
else
kvfree(p);
return n;
}
ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
struct page ***pages, size_t maxsize,
size_t *start)
{
struct page **p;
if (maxsize > i->count)
maxsize = i->count;
if (unlikely(iov_iter_is_pipe(i)))
return pipe_get_pages_alloc(i, pages, maxsize, start);
if (unlikely(iov_iter_is_discard(i)))
return -EFAULT;
iterate_all_kinds(i, maxsize, v, ({
unsigned long addr = (unsigned long)v.iov_base;
size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
int n;
int res;
addr &= ~(PAGE_SIZE - 1);
n = DIV_ROUND_UP(len, PAGE_SIZE);
p = get_pages_array(n);
if (!p)
return -ENOMEM;
res = get_user_pages_fast(addr, n,
iov_iter_rw(i) != WRITE ? FOLL_WRITE : 0, p);
if (unlikely(res < 0)) {
kvfree(p);
return res;
}
*pages = p;
return (res == n ? len : res * PAGE_SIZE) - *start;
0;}),({
/* can't be more than PAGE_SIZE */
*start = v.bv_offset;
*pages = p = get_pages_array(1);
if (!p)
return -ENOMEM;
get_page(*p = v.bv_page);
return v.bv_len;
}),({
return -EFAULT;
})
)
return 0;
}
EXPORT_SYMBOL(iov_iter_get_pages_alloc);
size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum,
struct iov_iter *i)
{
char *to = addr;
__wsum sum, next;
size_t off = 0;
sum = *csum;
if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
WARN_ON(1);
return 0;
}
iterate_and_advance(i, bytes, v, ({
next = csum_and_copy_from_user(v.iov_base,
(to += v.iov_len) - v.iov_len,
v.iov_len);
if (next) {
sum = csum_block_add(sum, next, off);
off += v.iov_len;
}
next ? 0 : v.iov_len;
}), ({
char *p = kmap_atomic(v.bv_page);
sum = csum_and_memcpy((to += v.bv_len) - v.bv_len,
p + v.bv_offset, v.bv_len,
sum, off);
kunmap_atomic(p);
off += v.bv_len;
}),({
sum = csum_and_memcpy((to += v.iov_len) - v.iov_len,
v.iov_base, v.iov_len,
sum, off);
off += v.iov_len;
})
)
*csum = sum;
return bytes;
}
EXPORT_SYMBOL(csum_and_copy_from_iter);
bool csum_and_copy_from_iter_full(void *addr, size_t bytes, __wsum *csum,
struct iov_iter *i)
{
char *to = addr;
__wsum sum, next;
size_t off = 0;
sum = *csum;
if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
WARN_ON(1);
return false;
}
if (unlikely(i->count < bytes))
return false;
iterate_all_kinds(i, bytes, v, ({
next = csum_and_copy_from_user(v.iov_base,
(to += v.iov_len) - v.iov_len,
v.iov_len);
if (!next)
return false;
sum = csum_block_add(sum, next, off);
off += v.iov_len;
0;
}), ({
char *p = kmap_atomic(v.bv_page);
sum = csum_and_memcpy((to += v.bv_len) - v.bv_len,
p + v.bv_offset, v.bv_len,
sum, off);
kunmap_atomic(p);
off += v.bv_len;
}),({
sum = csum_and_memcpy((to += v.iov_len) - v.iov_len,
v.iov_base, v.iov_len,
sum, off);
off += v.iov_len;
})
)
*csum = sum;
iov_iter_advance(i, bytes);
return true;
}
EXPORT_SYMBOL(csum_and_copy_from_iter_full);
size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *_csstate,
struct iov_iter *i)
{
struct csum_state *csstate = _csstate;
const char *from = addr;
__wsum sum, next;
size_t off;
if (unlikely(iov_iter_is_pipe(i)))
return csum_and_copy_to_pipe_iter(addr, bytes, _csstate, i);
sum = csstate->csum;
off = csstate->off;
if (unlikely(iov_iter_is_discard(i))) {
WARN_ON(1); /* for now */
return 0;
}
iterate_and_advance(i, bytes, v, ({
next = csum_and_copy_to_user((from += v.iov_len) - v.iov_len,
v.iov_base,
v.iov_len);
if (next) {
sum = csum_block_add(sum, next, off);
off += v.iov_len;
}
next ? 0 : v.iov_len;
}), ({
char *p = kmap_atomic(v.bv_page);
sum = csum_and_memcpy(p + v.bv_offset,
(from += v.bv_len) - v.bv_len,
v.bv_len, sum, off);
kunmap_atomic(p);
off += v.bv_len;
}),({
sum = csum_and_memcpy(v.iov_base,
(from += v.iov_len) - v.iov_len,
v.iov_len, sum, off);
off += v.iov_len;
})
)
csstate->csum = sum;
csstate->off = off;
return bytes;
}
EXPORT_SYMBOL(csum_and_copy_to_iter);
size_t hash_and_copy_to_iter(const void *addr, size_t bytes, void *hashp,
struct iov_iter *i)
{
#ifdef CONFIG_CRYPTO_HASH
struct ahash_request *hash = hashp;
struct scatterlist sg;
size_t copied;
copied = copy_to_iter(addr, bytes, i);
sg_init_one(&sg, addr, copied);
ahash_request_set_crypt(hash, &sg, NULL, copied);
crypto_ahash_update(hash);
return copied;
#else
return 0;
#endif
}
EXPORT_SYMBOL(hash_and_copy_to_iter);
int iov_iter_npages(const struct iov_iter *i, int maxpages)
{
size_t size = i->count;
int npages = 0;
if (!size)
return 0;
if (unlikely(iov_iter_is_discard(i)))
return 0;
if (unlikely(iov_iter_is_pipe(i))) {
struct pipe_inode_info *pipe = i->pipe;
unsigned int iter_head;
size_t off;
if (!sanity(i))
return 0;
data_start(i, &iter_head, &off);
/* some of this one + all after this one */
npages = pipe_space_for_user(iter_head, pipe->tail, pipe);
if (npages >= maxpages)
return maxpages;
} else iterate_all_kinds(i, size, v, ({
unsigned long p = (unsigned long)v.iov_base;
npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE)
- p / PAGE_SIZE;
if (npages >= maxpages)
return maxpages;
0;}),({
npages++;
if (npages >= maxpages)
return maxpages;
}),({
unsigned long p = (unsigned long)v.iov_base;
npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE)
- p / PAGE_SIZE;
if (npages >= maxpages)
return maxpages;
})
)
return npages;
}
EXPORT_SYMBOL(iov_iter_npages);
const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags)
{
*new = *old;
if (unlikely(iov_iter_is_pipe(new))) {
WARN_ON(1);
return NULL;
}
if (unlikely(iov_iter_is_discard(new)))
return NULL;
if (iov_iter_is_bvec(new))
return new->bvec = kmemdup(new->bvec,
new->nr_segs * sizeof(struct bio_vec),
flags);
else
/* iovec and kvec have identical layout */
return new->iov = kmemdup(new->iov,
new->nr_segs * sizeof(struct iovec),
flags);
}
EXPORT_SYMBOL(dup_iter);
static int copy_compat_iovec_from_user(struct iovec *iov,
const struct iovec __user *uvec, unsigned long nr_segs)
{
const struct compat_iovec __user *uiov =
(const struct compat_iovec __user *)uvec;
int ret = -EFAULT, i;
if (!user_access_begin(uiov, nr_segs * sizeof(*uiov)))
return -EFAULT;
for (i = 0; i < nr_segs; i++) {
compat_uptr_t buf;
compat_ssize_t len;
unsafe_get_user(len, &uiov[i].iov_len, uaccess_end);
unsafe_get_user(buf, &uiov[i].iov_base, uaccess_end);
/* check for compat_size_t not fitting in compat_ssize_t .. */
if (len < 0) {
ret = -EINVAL;
goto uaccess_end;
}
iov[i].iov_base = compat_ptr(buf);
iov[i].iov_len = len;
}
ret = 0;
uaccess_end:
user_access_end();
return ret;
}
static int copy_iovec_from_user(struct iovec *iov,
const struct iovec __user *uvec, unsigned long nr_segs)
{
unsigned long seg;
if (copy_from_user(iov, uvec, nr_segs * sizeof(*uvec)))
return -EFAULT;
for (seg = 0; seg < nr_segs; seg++) {
if ((ssize_t)iov[seg].iov_len < 0)
return -EINVAL;
}
return 0;
}
struct iovec *iovec_from_user(const struct iovec __user *uvec,
unsigned long nr_segs, unsigned long fast_segs,
struct iovec *fast_iov, bool compat)
{
struct iovec *iov = fast_iov;
int ret;
/*
* SuS says "The readv() function *may* fail if the iovcnt argument was
* less than or equal to 0, or greater than {IOV_MAX}. Linux has
* traditionally returned zero for zero segments, so...
*/
if (nr_segs == 0)
return iov;
if (nr_segs > UIO_MAXIOV)
return ERR_PTR(-EINVAL);
if (nr_segs > fast_segs) {
iov = kmalloc_array(nr_segs, sizeof(struct iovec), GFP_KERNEL);
if (!iov)
return ERR_PTR(-ENOMEM);
}
if (compat)
ret = copy_compat_iovec_from_user(iov, uvec, nr_segs);
else
ret = copy_iovec_from_user(iov, uvec, nr_segs);
if (ret) {
if (iov != fast_iov)
kfree(iov);
return ERR_PTR(ret);
}
return iov;
}
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)
{
ssize_t total_len = 0;
unsigned long seg;
struct iovec *iov;
iov = iovec_from_user(uvec, nr_segs, fast_segs, *iovp, compat);
if (IS_ERR(iov)) {
*iovp = NULL;
return PTR_ERR(iov);
}
/*
* According to the Single Unix Specification we should return EINVAL if
* an element length is < 0 when cast to ssize_t or if the total length
* would overflow the ssize_t return value of the system call.
*
* Linux caps all read/write calls to MAX_RW_COUNT, and avoids the
* overflow case.
*/
for (seg = 0; seg < nr_segs; seg++) {
ssize_t len = (ssize_t)iov[seg].iov_len;
if (!access_ok(iov[seg].iov_base, len)) {
if (iov != *iovp)
kfree(iov);
*iovp = NULL;
return -EFAULT;
}
if (len > MAX_RW_COUNT - total_len) {
len = MAX_RW_COUNT - total_len;
iov[seg].iov_len = len;
}
total_len += len;
}
iov_iter_init(i, type, iov, nr_segs, total_len);
if (iov == *iovp)
*iovp = NULL;
else
*iovp = iov;
return total_len;
}
/**
* import_iovec() - Copy an array of &struct iovec from userspace
* into the kernel, check that it is valid, and initialize a new
* &struct iov_iter iterator to access it.
*
* @type: One of %READ or %WRITE.
* @uvec: Pointer to the userspace array.
* @nr_segs: Number of elements in userspace array.
* @fast_segs: Number of elements in @iov.
* @iovp: (input and output parameter) Pointer to pointer to (usually small
* on-stack) kernel array.
* @i: Pointer to iterator that will be initialized on success.
*
* If the array pointed to by *@iov is large enough to hold all @nr_segs,
* then this function places %NULL in *@iov on return. Otherwise, a new
* array will be allocated and the result placed in *@iov. This means that
* the caller may call kfree() on *@iov regardless of whether the small
* on-stack array was used or not (and regardless of whether this function
* returns an error or not).
*
* Return: Negative error code on error, bytes imported on success
*/
ssize_t import_iovec(int type, const struct iovec __user *uvec,
unsigned nr_segs, unsigned fast_segs,
struct iovec **iovp, struct iov_iter *i)
{
return __import_iovec(type, uvec, nr_segs, fast_segs, iovp, i,
in_compat_syscall());
}
EXPORT_SYMBOL(import_iovec);
int import_single_range(int rw, void __user *buf, size_t len,
struct iovec *iov, struct iov_iter *i)
{
if (len > MAX_RW_COUNT)
len = MAX_RW_COUNT;
if (unlikely(!access_ok(buf, len)))
return -EFAULT;
iov->iov_base = buf;
iov->iov_len = len;
iov_iter_init(i, rw, iov, 1, len);
return 0;
}
EXPORT_SYMBOL(import_single_range);
int iov_iter_for_each_range(struct iov_iter *i, size_t bytes,
int (*f)(struct kvec *vec, void *context),
void *context)
{
struct kvec w;
int err = -EINVAL;
if (!bytes)
return 0;
iterate_all_kinds(i, bytes, v, -EINVAL, ({
w.iov_base = kmap(v.bv_page) + v.bv_offset;
w.iov_len = v.bv_len;
err = f(&w, context);
kunmap(v.bv_page);
err;}), ({
w = v;
err = f(&w, context);})
)
return err;
}
EXPORT_SYMBOL(iov_iter_for_each_range);