linux/mm/iov_iter.c

814 lines
18 KiB
C
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#include <linux/export.h>
#include <linux/uio.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#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_bvec(i, n, __v, __p, skip, STEP) { \
size_t wanted = n; \
__p = i->bvec; \
__v.bv_len = min_t(size_t, n, __p->bv_len - skip); \
if (likely(__v.bv_len)) { \
__v.bv_page = __p->bv_page; \
__v.bv_offset = __p->bv_offset + skip; \
(void)(STEP); \
skip += __v.bv_len; \
n -= __v.bv_len; \
} \
while (unlikely(n)) { \
__p++; \
__v.bv_len = min_t(size_t, n, __p->bv_len); \
if (unlikely(!__v.bv_len)) \
continue; \
__v.bv_page = __p->bv_page; \
__v.bv_offset = __p->bv_offset; \
(void)(STEP); \
skip = __v.bv_len; \
n -= __v.bv_len; \
} \
n = wanted; \
}
#define iterate_all_kinds(i, n, v, I, B) { \
size_t skip = i->iov_offset; \
if (unlikely(i->type & ITER_BVEC)) { \
const struct bio_vec *bvec; \
struct bio_vec v; \
iterate_bvec(i, n, v, bvec, skip, (B)) \
} 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) { \
size_t skip = i->iov_offset; \
if (unlikely(i->type & ITER_BVEC)) { \
const struct bio_vec *bvec; \
struct bio_vec v; \
iterate_bvec(i, n, v, bvec, skip, (B)) \
if (skip == bvec->bv_len) { \
bvec++; \
skip = 0; \
} \
i->nr_segs -= bvec - i->bvec; \
i->bvec = bvec; \
} 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 size_t copy_to_iter_iovec(void *from, size_t bytes, struct iov_iter *i)
{
size_t skip, copy, left, wanted;
const struct iovec *iov;
char __user *buf;
if (unlikely(bytes > i->count))
bytes = i->count;
if (unlikely(!bytes))
return 0;
wanted = bytes;
iov = i->iov;
skip = i->iov_offset;
buf = iov->iov_base + skip;
copy = min(bytes, iov->iov_len - skip);
left = __copy_to_user(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 = __copy_to_user(buf, from, copy);
copy -= left;
skip = copy;
from += copy;
bytes -= copy;
}
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_from_iter_iovec(void *to, size_t bytes, struct iov_iter *i)
{
size_t skip, copy, left, wanted;
const struct iovec *iov;
char __user *buf;
if (unlikely(bytes > i->count))
bytes = i->count;
if (unlikely(!bytes))
return 0;
wanted = bytes;
iov = i->iov;
skip = i->iov_offset;
buf = iov->iov_base + skip;
copy = min(bytes, iov->iov_len - skip);
left = __copy_from_user(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 = __copy_from_user(to, buf, copy);
copy -= left;
skip = copy;
to += copy;
bytes -= copy;
}
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_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;
wanted = bytes;
iov = i->iov;
skip = i->iov_offset;
buf = iov->iov_base + skip;
copy = min(bytes, iov->iov_len - skip);
if (!fault_in_pages_writeable(buf, copy)) {
kaddr = kmap_atomic(page);
from = kaddr + offset;
/* first chunk, usually the only one */
left = __copy_to_user_inatomic(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 = __copy_to_user_inatomic(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 = __copy_to_user(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 = __copy_to_user(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;
wanted = bytes;
iov = i->iov;
skip = i->iov_offset;
buf = iov->iov_base + skip;
copy = min(bytes, iov->iov_len - skip);
if (!fault_in_pages_readable(buf, copy)) {
kaddr = kmap_atomic(page);
to = kaddr + offset;
/* first chunk, usually the only one */
left = __copy_from_user_inatomic(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 = __copy_from_user_inatomic(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 = __copy_from_user(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 = __copy_from_user(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;
}
static size_t zero_iovec(size_t bytes, struct iov_iter *i)
{
size_t skip, copy, left, wanted;
const struct iovec *iov;
char __user *buf;
if (unlikely(bytes > i->count))
bytes = i->count;
if (unlikely(!bytes))
return 0;
wanted = bytes;
iov = i->iov;
skip = i->iov_offset;
buf = iov->iov_base + skip;
copy = min(bytes, iov->iov_len - skip);
left = __clear_user(buf, copy);
copy -= left;
skip += copy;
bytes -= copy;
while (unlikely(!left && bytes)) {
iov++;
buf = iov->iov_base;
copy = min(bytes, iov->iov_len);
left = __clear_user(buf, copy);
copy -= left;
skip = copy;
bytes -= copy;
}
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;
}
/*
* Fault in the first iovec of the given iov_iter, to a maximum length
* of bytes. Returns 0 on success, or non-zero if the memory could not be
* accessed (ie. because it is an invalid address).
*
* writev-intensive code may want this to prefault several iovecs -- that
* would be possible (callers must not rely on the fact that _only_ the
* first iovec will be faulted with the current implementation).
*/
int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
{
if (!(i->type & ITER_BVEC)) {
char __user *buf = i->iov->iov_base + i->iov_offset;
bytes = min(bytes, i->iov->iov_len - i->iov_offset);
return fault_in_pages_readable(buf, bytes);
}
return 0;
}
EXPORT_SYMBOL(iov_iter_fault_in_readable);
void iov_iter_init(struct iov_iter *i, int direction,
const struct iovec *iov, unsigned long nr_segs,
size_t count)
{
/* It will get better. Eventually... */
if (segment_eq(get_fs(), KERNEL_DS))
direction |= ITER_KVEC;
i->type = direction;
i->iov = iov;
i->nr_segs = nr_segs;
i->iov_offset = 0;
i->count = count;
}
EXPORT_SYMBOL(iov_iter_init);
static ssize_t get_pages_alloc_iovec(struct iov_iter *i,
struct page ***pages, size_t maxsize,
size_t *start)
{
size_t offset = i->iov_offset;
const struct iovec *iov = i->iov;
size_t len;
unsigned long addr;
void *p;
int n;
int res;
len = iov->iov_len - offset;
if (len > i->count)
len = i->count;
if (len > maxsize)
len = maxsize;
addr = (unsigned long)iov->iov_base + offset;
len += *start = addr & (PAGE_SIZE - 1);
addr &= ~(PAGE_SIZE - 1);
n = (len + PAGE_SIZE - 1) / PAGE_SIZE;
p = kmalloc(n * sizeof(struct page *), GFP_KERNEL);
if (!p)
p = vmalloc(n * sizeof(struct page *));
if (!p)
return -ENOMEM;
res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, p);
if (unlikely(res < 0)) {
kvfree(p);
return res;
}
*pages = p;
return (res == n ? len : res * PAGE_SIZE) - *start;
}
static void memcpy_from_page(char *to, struct page *page, size_t offset, size_t len)
{
char *from = kmap_atomic(page);
memcpy(to, from + offset, len);
kunmap_atomic(from);
}
static void memcpy_to_page(struct page *page, size_t offset, char *from, size_t len)
{
char *to = kmap_atomic(page);
memcpy(to + offset, from, len);
kunmap_atomic(to);
}
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 size_t copy_to_iter_bvec(void *from, size_t bytes, struct iov_iter *i)
{
size_t skip, copy, wanted;
const struct bio_vec *bvec;
if (unlikely(bytes > i->count))
bytes = i->count;
if (unlikely(!bytes))
return 0;
wanted = bytes;
bvec = i->bvec;
skip = i->iov_offset;
copy = min_t(size_t, bytes, bvec->bv_len - skip);
memcpy_to_page(bvec->bv_page, skip + bvec->bv_offset, from, copy);
skip += copy;
from += copy;
bytes -= copy;
while (bytes) {
bvec++;
copy = min(bytes, (size_t)bvec->bv_len);
memcpy_to_page(bvec->bv_page, bvec->bv_offset, from, copy);
skip = copy;
from += copy;
bytes -= copy;
}
if (skip == bvec->bv_len) {
bvec++;
skip = 0;
}
i->count -= wanted - bytes;
i->nr_segs -= bvec - i->bvec;
i->bvec = bvec;
i->iov_offset = skip;
return wanted - bytes;
}
static size_t copy_from_iter_bvec(void *to, size_t bytes, struct iov_iter *i)
{
size_t skip, copy, wanted;
const struct bio_vec *bvec;
if (unlikely(bytes > i->count))
bytes = i->count;
if (unlikely(!bytes))
return 0;
wanted = bytes;
bvec = i->bvec;
skip = i->iov_offset;
copy = min(bytes, bvec->bv_len - skip);
memcpy_from_page(to, bvec->bv_page, bvec->bv_offset + skip, copy);
to += copy;
skip += copy;
bytes -= copy;
while (bytes) {
bvec++;
copy = min(bytes, (size_t)bvec->bv_len);
memcpy_from_page(to, bvec->bv_page, bvec->bv_offset, copy);
skip = copy;
to += copy;
bytes -= copy;
}
if (skip == bvec->bv_len) {
bvec++;
skip = 0;
}
i->count -= wanted;
i->nr_segs -= bvec - i->bvec;
i->bvec = bvec;
i->iov_offset = skip;
return wanted;
}
static size_t copy_page_to_iter_bvec(struct page *page, size_t offset,
size_t bytes, struct iov_iter *i)
{
void *kaddr = kmap_atomic(page);
size_t wanted = copy_to_iter_bvec(kaddr + offset, bytes, i);
kunmap_atomic(kaddr);
return wanted;
}
static size_t copy_page_from_iter_bvec(struct page *page, size_t offset,
size_t bytes, struct iov_iter *i)
{
void *kaddr = kmap_atomic(page);
size_t wanted = copy_from_iter_bvec(kaddr + offset, bytes, i);
kunmap_atomic(kaddr);
return wanted;
}
static size_t zero_bvec(size_t bytes, struct iov_iter *i)
{
size_t skip, copy, wanted;
const struct bio_vec *bvec;
if (unlikely(bytes > i->count))
bytes = i->count;
if (unlikely(!bytes))
return 0;
wanted = bytes;
bvec = i->bvec;
skip = i->iov_offset;
copy = min_t(size_t, bytes, bvec->bv_len - skip);
memzero_page(bvec->bv_page, skip + bvec->bv_offset, copy);
skip += copy;
bytes -= copy;
while (bytes) {
bvec++;
copy = min(bytes, (size_t)bvec->bv_len);
memzero_page(bvec->bv_page, bvec->bv_offset, copy);
skip = copy;
bytes -= copy;
}
if (skip == bvec->bv_len) {
bvec++;
skip = 0;
}
i->count -= wanted - bytes;
i->nr_segs -= bvec - i->bvec;
i->bvec = bvec;
i->iov_offset = skip;
return wanted - bytes;
}
static ssize_t get_pages_alloc_bvec(struct iov_iter *i,
struct page ***pages, size_t maxsize,
size_t *start)
{
const struct bio_vec *bvec = i->bvec;
size_t len = bvec->bv_len - i->iov_offset;
if (len > i->count)
len = i->count;
if (len > maxsize)
len = maxsize;
*start = bvec->bv_offset + i->iov_offset;
*pages = kmalloc(sizeof(struct page *), GFP_KERNEL);
if (!*pages)
return -ENOMEM;
get_page(**pages = bvec->bv_page);
return len;
}
size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i)
{
if (i->type & ITER_BVEC)
return copy_page_to_iter_bvec(page, offset, bytes, i);
else
return copy_page_to_iter_iovec(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 (i->type & ITER_BVEC)
return copy_page_from_iter_bvec(page, offset, bytes, i);
else
return copy_page_from_iter_iovec(page, offset, bytes, i);
}
EXPORT_SYMBOL(copy_page_from_iter);
size_t copy_to_iter(void *addr, size_t bytes, struct iov_iter *i)
{
if (i->type & ITER_BVEC)
return copy_to_iter_bvec(addr, bytes, i);
else
return copy_to_iter_iovec(addr, bytes, i);
}
EXPORT_SYMBOL(copy_to_iter);
size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
{
if (i->type & ITER_BVEC)
return copy_from_iter_bvec(addr, bytes, i);
else
return copy_from_iter_iovec(addr, bytes, i);
}
EXPORT_SYMBOL(copy_from_iter);
size_t iov_iter_zero(size_t bytes, struct iov_iter *i)
{
if (i->type & ITER_BVEC) {
return zero_bvec(bytes, i);
} else {
return zero_iovec(bytes, i);
}
}
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;
iterate_all_kinds(i, bytes, v,
__copy_from_user_inatomic((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)
)
kunmap_atomic(kaddr);
return bytes;
}
EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
void iov_iter_advance(struct iov_iter *i, size_t size)
{
iterate_and_advance(i, size, v, 0, 0)
}
EXPORT_SYMBOL(iov_iter_advance);
/*
* Return the count of just the current iov_iter segment.
*/
size_t iov_iter_single_seg_count(const struct iov_iter *i)
{
if (i->nr_segs == 1)
return i->count;
else if (i->type & ITER_BVEC)
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);
unsigned long iov_iter_alignment(const struct iov_iter *i)
{
unsigned long res = 0;
size_t size = i->count;
if (!size)
return 0;
iterate_all_kinds(i, size, v,
(res |= (unsigned long)v.iov_base | v.iov_len, 0),
res |= v.bv_offset | v.bv_len
)
return res;
}
EXPORT_SYMBOL(iov_iter_alignment);
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 (!maxsize)
return 0;
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, (i->type & WRITE) != WRITE, 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 0;
}
EXPORT_SYMBOL(iov_iter_get_pages);
ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
struct page ***pages, size_t maxsize,
size_t *start)
{
if (i->type & ITER_BVEC)
return get_pages_alloc_bvec(i, pages, maxsize, start);
else
return get_pages_alloc_iovec(i, pages, maxsize, start);
}
EXPORT_SYMBOL(iov_iter_get_pages_alloc);
int iov_iter_npages(const struct iov_iter *i, int maxpages)
{
size_t size = i->count;
int npages = 0;
if (!size)
return 0;
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;
})
)
return npages;
}
EXPORT_SYMBOL(iov_iter_npages);