c749d9b7eb
generic/077 on x86_32 CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP=y with highmem,
on huge=always tmpfs, issues a warning and then hangs (interruptibly):
WARNING: CPU: 5 PID: 3517 at mm/highmem.c:622 kunmap_local_indexed+0x62/0xc9
CPU: 5 UID: 0 PID: 3517 Comm: cp Not tainted 6.12.0-rc4 #2
...
copy_page_from_iter_atomic+0xa6/0x5ec
generic_perform_write+0xf6/0x1b4
shmem_file_write_iter+0x54/0x67
Fix copy_page_from_iter_atomic() by limiting it in that case
(include/linux/skbuff.h skb_frag_must_loop() does similar).
But going forward, perhaps CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP is too
surprising, has outlived its usefulness, and should just be removed?
Fixes: 908a1ad894
("iov_iter: Handle compound highmem pages in copy_page_from_iter_atomic()")
Signed-off-by: Hugh Dickins <hughd@google.com>
Link: https://lore.kernel.org/r/dd5f0c89-186e-18e1-4f43-19a60f5a9774@google.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: stable@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
1905 lines
48 KiB
C
1905 lines
48 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/export.h>
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#include <linux/bvec.h>
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#include <linux/fault-inject-usercopy.h>
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#include <linux/uio.h>
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#include <linux/pagemap.h>
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#include <linux/highmem.h>
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#include <linux/slab.h>
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#include <linux/vmalloc.h>
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#include <linux/splice.h>
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#include <linux/compat.h>
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#include <linux/scatterlist.h>
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#include <linux/instrumented.h>
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#include <linux/iov_iter.h>
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static __always_inline
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size_t copy_to_user_iter(void __user *iter_to, size_t progress,
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size_t len, void *from, void *priv2)
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{
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if (should_fail_usercopy())
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return len;
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if (access_ok(iter_to, len)) {
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from += progress;
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instrument_copy_to_user(iter_to, from, len);
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len = raw_copy_to_user(iter_to, from, len);
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}
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return len;
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}
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static __always_inline
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size_t copy_to_user_iter_nofault(void __user *iter_to, size_t progress,
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size_t len, void *from, void *priv2)
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{
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ssize_t res;
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if (should_fail_usercopy())
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return len;
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from += progress;
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res = copy_to_user_nofault(iter_to, from, len);
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return res < 0 ? len : res;
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}
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static __always_inline
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size_t copy_from_user_iter(void __user *iter_from, size_t progress,
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size_t len, void *to, void *priv2)
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{
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size_t res = len;
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if (should_fail_usercopy())
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return len;
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if (access_ok(iter_from, len)) {
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to += progress;
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instrument_copy_from_user_before(to, iter_from, len);
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res = raw_copy_from_user(to, iter_from, len);
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instrument_copy_from_user_after(to, iter_from, len, res);
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}
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return res;
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}
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static __always_inline
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size_t memcpy_to_iter(void *iter_to, size_t progress,
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size_t len, void *from, void *priv2)
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{
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memcpy(iter_to, from + progress, len);
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return 0;
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}
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static __always_inline
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size_t memcpy_from_iter(void *iter_from, size_t progress,
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size_t len, void *to, void *priv2)
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{
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memcpy(to + progress, iter_from, len);
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return 0;
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}
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/*
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* fault_in_iov_iter_readable - fault in iov iterator for reading
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* @i: iterator
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* @size: maximum length
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*
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* Fault in one or more iovecs of the given iov_iter, to a maximum length of
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* @size. For each iovec, fault in each page that constitutes the iovec.
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*
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* Returns the number of bytes not faulted in (like copy_to_user() and
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* copy_from_user()).
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*
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* Always returns 0 for non-userspace iterators.
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*/
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size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t size)
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{
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if (iter_is_ubuf(i)) {
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size_t n = min(size, iov_iter_count(i));
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n -= fault_in_readable(i->ubuf + i->iov_offset, n);
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return size - n;
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} else if (iter_is_iovec(i)) {
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size_t count = min(size, iov_iter_count(i));
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const struct iovec *p;
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size_t skip;
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size -= count;
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for (p = iter_iov(i), skip = i->iov_offset; count; p++, skip = 0) {
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size_t len = min(count, p->iov_len - skip);
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size_t ret;
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if (unlikely(!len))
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continue;
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ret = fault_in_readable(p->iov_base + skip, len);
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count -= len - ret;
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if (ret)
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break;
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}
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return count + size;
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}
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return 0;
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}
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EXPORT_SYMBOL(fault_in_iov_iter_readable);
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/*
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* fault_in_iov_iter_writeable - fault in iov iterator for writing
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* @i: iterator
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* @size: maximum length
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*
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* Faults in the iterator using get_user_pages(), i.e., without triggering
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* hardware page faults. This is primarily useful when we already know that
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* some or all of the pages in @i aren't in memory.
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*
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* Returns the number of bytes not faulted in, like copy_to_user() and
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* copy_from_user().
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*
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* Always returns 0 for non-user-space iterators.
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*/
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size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t size)
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{
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if (iter_is_ubuf(i)) {
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size_t n = min(size, iov_iter_count(i));
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n -= fault_in_safe_writeable(i->ubuf + i->iov_offset, n);
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return size - n;
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} else if (iter_is_iovec(i)) {
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size_t count = min(size, iov_iter_count(i));
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const struct iovec *p;
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size_t skip;
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size -= count;
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for (p = iter_iov(i), skip = i->iov_offset; count; p++, skip = 0) {
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size_t len = min(count, p->iov_len - skip);
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size_t ret;
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if (unlikely(!len))
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continue;
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ret = fault_in_safe_writeable(p->iov_base + skip, len);
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count -= len - ret;
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if (ret)
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break;
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}
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return count + size;
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}
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return 0;
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}
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EXPORT_SYMBOL(fault_in_iov_iter_writeable);
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void iov_iter_init(struct iov_iter *i, unsigned int direction,
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const struct iovec *iov, unsigned long nr_segs,
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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_IOVEC,
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.nofault = false,
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.data_source = direction,
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.__iov = iov,
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.nr_segs = nr_segs,
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.iov_offset = 0,
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.count = count
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};
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}
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EXPORT_SYMBOL(iov_iter_init);
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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 (WARN_ON_ONCE(i->data_source))
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return 0;
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if (user_backed_iter(i))
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might_fault();
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return iterate_and_advance(i, bytes, (void *)addr,
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copy_to_user_iter, memcpy_to_iter);
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}
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EXPORT_SYMBOL(_copy_to_iter);
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#ifdef CONFIG_ARCH_HAS_COPY_MC
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static __always_inline
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size_t copy_to_user_iter_mc(void __user *iter_to, size_t progress,
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size_t len, void *from, void *priv2)
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{
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if (access_ok(iter_to, len)) {
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from += progress;
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instrument_copy_to_user(iter_to, from, len);
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len = copy_mc_to_user(iter_to, from, len);
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}
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return len;
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}
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static __always_inline
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size_t memcpy_to_iter_mc(void *iter_to, size_t progress,
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size_t len, void *from, void *priv2)
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{
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return copy_mc_to_kernel(iter_to, from + progress, len);
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}
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/**
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* _copy_mc_to_iter - copy to iter with source memory error exception handling
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* @addr: source kernel address
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* @bytes: total transfer length
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* @i: destination iterator
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*
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* The pmem driver deploys this for the dax operation
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* (dax_copy_to_iter()) for dax reads (bypass page-cache and the
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* block-layer). Upon #MC read(2) aborts and returns EIO or the bytes
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* successfully copied.
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*
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* The main differences between this and typical _copy_to_iter().
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*
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* * Typical tail/residue handling after a fault retries the copy
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* byte-by-byte until the fault happens again. Re-triggering machine
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* checks is potentially fatal so the implementation uses source
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* alignment and poison alignment assumptions to avoid re-triggering
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* hardware exceptions.
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*
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* * ITER_KVEC and ITER_BVEC can return short copies. Compare to
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* copy_to_iter() where only ITER_IOVEC attempts might return a short copy.
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*
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* Return: number of bytes copied (may be %0)
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*/
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size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
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{
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if (WARN_ON_ONCE(i->data_source))
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return 0;
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if (user_backed_iter(i))
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might_fault();
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return iterate_and_advance(i, bytes, (void *)addr,
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copy_to_user_iter_mc, memcpy_to_iter_mc);
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}
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EXPORT_SYMBOL_GPL(_copy_mc_to_iter);
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#endif /* CONFIG_ARCH_HAS_COPY_MC */
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static __always_inline
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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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return iterate_and_advance(i, bytes, addr,
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copy_from_user_iter, memcpy_from_iter);
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}
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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 (WARN_ON_ONCE(!i->data_source))
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return 0;
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if (user_backed_iter(i))
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might_fault();
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return __copy_from_iter(addr, bytes, i);
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}
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EXPORT_SYMBOL(_copy_from_iter);
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static __always_inline
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size_t copy_from_user_iter_nocache(void __user *iter_from, size_t progress,
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size_t len, void *to, void *priv2)
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{
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return __copy_from_user_inatomic_nocache(to + progress, iter_from, len);
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}
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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 (WARN_ON_ONCE(!i->data_source))
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return 0;
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return iterate_and_advance(i, bytes, addr,
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copy_from_user_iter_nocache,
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memcpy_from_iter);
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}
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EXPORT_SYMBOL(_copy_from_iter_nocache);
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#ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
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static __always_inline
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size_t copy_from_user_iter_flushcache(void __user *iter_from, size_t progress,
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size_t len, void *to, void *priv2)
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{
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return __copy_from_user_flushcache(to + progress, iter_from, len);
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}
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static __always_inline
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size_t memcpy_from_iter_flushcache(void *iter_from, size_t progress,
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size_t len, void *to, void *priv2)
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{
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memcpy_flushcache(to + progress, iter_from, len);
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return 0;
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}
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/**
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* _copy_from_iter_flushcache - write destination through cpu cache
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* @addr: destination kernel address
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* @bytes: total transfer length
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* @i: source iterator
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*
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* The pmem driver arranges for filesystem-dax to use this facility via
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* dax_copy_from_iter() for ensuring that writes to persistent memory
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* are flushed through the CPU cache. It is differentiated from
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* _copy_from_iter_nocache() in that guarantees all data is flushed for
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* all iterator types. The _copy_from_iter_nocache() only attempts to
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* bypass the cache for the ITER_IOVEC case, and on some archs may use
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* instructions that strand dirty-data in the cache.
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*
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* Return: number of bytes copied (may be %0)
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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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{
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if (WARN_ON_ONCE(!i->data_source))
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return 0;
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return iterate_and_advance(i, bytes, addr,
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copy_from_user_iter_flushcache,
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memcpy_from_iter_flushcache);
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}
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EXPORT_SYMBOL_GPL(_copy_from_iter_flushcache);
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#endif
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static inline bool page_copy_sane(struct page *page, size_t offset, size_t n)
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{
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struct page *head;
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size_t v = n + offset;
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/*
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* The general case needs to access the page order in order
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* to compute the page size.
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* However, we mostly deal with order-0 pages and thus can
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* avoid a possible cache line miss for requests that fit all
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* page orders.
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*/
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if (n <= v && v <= PAGE_SIZE)
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return true;
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head = compound_head(page);
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v += (page - head) << PAGE_SHIFT;
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if (WARN_ON(n > v || v > page_size(head)))
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return false;
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return true;
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}
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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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{
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size_t res = 0;
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if (!page_copy_sane(page, offset, bytes))
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return 0;
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if (WARN_ON_ONCE(i->data_source))
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return 0;
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page += offset / PAGE_SIZE; // first subpage
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offset %= PAGE_SIZE;
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while (1) {
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void *kaddr = kmap_local_page(page);
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size_t n = min(bytes, (size_t)PAGE_SIZE - offset);
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n = _copy_to_iter(kaddr + offset, n, i);
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kunmap_local(kaddr);
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res += n;
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bytes -= n;
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if (!bytes || !n)
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break;
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offset += n;
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if (offset == PAGE_SIZE) {
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page++;
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offset = 0;
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}
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}
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return res;
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}
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EXPORT_SYMBOL(copy_page_to_iter);
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size_t copy_page_to_iter_nofault(struct page *page, unsigned offset, size_t bytes,
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struct iov_iter *i)
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{
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size_t res = 0;
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if (!page_copy_sane(page, offset, bytes))
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return 0;
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if (WARN_ON_ONCE(i->data_source))
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return 0;
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page += offset / PAGE_SIZE; // first subpage
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offset %= PAGE_SIZE;
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while (1) {
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void *kaddr = kmap_local_page(page);
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size_t n = min(bytes, (size_t)PAGE_SIZE - offset);
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n = iterate_and_advance(i, n, kaddr + offset,
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copy_to_user_iter_nofault,
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memcpy_to_iter);
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kunmap_local(kaddr);
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res += n;
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bytes -= n;
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if (!bytes || !n)
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break;
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offset += n;
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if (offset == PAGE_SIZE) {
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page++;
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offset = 0;
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}
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}
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return res;
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}
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EXPORT_SYMBOL(copy_page_to_iter_nofault);
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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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{
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size_t res = 0;
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if (!page_copy_sane(page, offset, bytes))
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return 0;
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page += offset / PAGE_SIZE; // first subpage
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offset %= PAGE_SIZE;
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while (1) {
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void *kaddr = kmap_local_page(page);
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size_t n = min(bytes, (size_t)PAGE_SIZE - offset);
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n = _copy_from_iter(kaddr + offset, n, i);
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kunmap_local(kaddr);
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res += n;
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bytes -= n;
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if (!bytes || !n)
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break;
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offset += n;
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if (offset == PAGE_SIZE) {
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page++;
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offset = 0;
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}
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}
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return res;
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}
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EXPORT_SYMBOL(copy_page_from_iter);
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static __always_inline
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size_t zero_to_user_iter(void __user *iter_to, size_t progress,
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size_t len, void *priv, void *priv2)
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{
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return clear_user(iter_to, len);
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}
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static __always_inline
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size_t zero_to_iter(void *iter_to, size_t progress,
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size_t len, void *priv, void *priv2)
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{
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memset(iter_to, 0, len);
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return 0;
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}
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size_t iov_iter_zero(size_t bytes, struct iov_iter *i)
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{
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return iterate_and_advance(i, bytes, NULL,
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zero_to_user_iter, zero_to_iter);
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}
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EXPORT_SYMBOL(iov_iter_zero);
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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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{
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size_t n, copied = 0;
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bool uses_kmap = IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP) ||
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PageHighMem(page);
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if (!page_copy_sane(page, offset, bytes))
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return 0;
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if (WARN_ON_ONCE(!i->data_source))
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return 0;
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do {
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char *p;
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n = bytes - copied;
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if (uses_kmap) {
|
|
page += offset / PAGE_SIZE;
|
|
offset %= PAGE_SIZE;
|
|
n = min_t(size_t, n, PAGE_SIZE - offset);
|
|
}
|
|
|
|
p = kmap_atomic(page) + offset;
|
|
n = __copy_from_iter(p, n, i);
|
|
kunmap_atomic(p);
|
|
copied += n;
|
|
offset += n;
|
|
} while (uses_kmap && copied != bytes && n > 0);
|
|
|
|
return copied;
|
|
}
|
|
EXPORT_SYMBOL(copy_page_from_iter_atomic);
|
|
|
|
static void iov_iter_bvec_advance(struct iov_iter *i, size_t size)
|
|
{
|
|
const struct bio_vec *bvec, *end;
|
|
|
|
if (!i->count)
|
|
return;
|
|
i->count -= size;
|
|
|
|
size += i->iov_offset;
|
|
|
|
for (bvec = i->bvec, end = bvec + i->nr_segs; bvec < end; bvec++) {
|
|
if (likely(size < bvec->bv_len))
|
|
break;
|
|
size -= bvec->bv_len;
|
|
}
|
|
i->iov_offset = size;
|
|
i->nr_segs -= bvec - i->bvec;
|
|
i->bvec = bvec;
|
|
}
|
|
|
|
static void iov_iter_iovec_advance(struct iov_iter *i, size_t size)
|
|
{
|
|
const struct iovec *iov, *end;
|
|
|
|
if (!i->count)
|
|
return;
|
|
i->count -= size;
|
|
|
|
size += i->iov_offset; // from beginning of current segment
|
|
for (iov = iter_iov(i), end = iov + i->nr_segs; iov < end; iov++) {
|
|
if (likely(size < iov->iov_len))
|
|
break;
|
|
size -= iov->iov_len;
|
|
}
|
|
i->iov_offset = size;
|
|
i->nr_segs -= iov - iter_iov(i);
|
|
i->__iov = iov;
|
|
}
|
|
|
|
static void iov_iter_folioq_advance(struct iov_iter *i, size_t size)
|
|
{
|
|
const struct folio_queue *folioq = i->folioq;
|
|
unsigned int slot = i->folioq_slot;
|
|
|
|
if (!i->count)
|
|
return;
|
|
i->count -= size;
|
|
|
|
if (slot >= folioq_nr_slots(folioq)) {
|
|
folioq = folioq->next;
|
|
slot = 0;
|
|
}
|
|
|
|
size += i->iov_offset; /* From beginning of current segment. */
|
|
do {
|
|
size_t fsize = folioq_folio_size(folioq, slot);
|
|
|
|
if (likely(size < fsize))
|
|
break;
|
|
size -= fsize;
|
|
slot++;
|
|
if (slot >= folioq_nr_slots(folioq) && folioq->next) {
|
|
folioq = folioq->next;
|
|
slot = 0;
|
|
}
|
|
} while (size);
|
|
|
|
i->iov_offset = size;
|
|
i->folioq_slot = slot;
|
|
i->folioq = folioq;
|
|
}
|
|
|
|
void iov_iter_advance(struct iov_iter *i, size_t size)
|
|
{
|
|
if (unlikely(i->count < size))
|
|
size = i->count;
|
|
if (likely(iter_is_ubuf(i)) || unlikely(iov_iter_is_xarray(i))) {
|
|
i->iov_offset += size;
|
|
i->count -= size;
|
|
} else if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) {
|
|
/* iovec and kvec have identical layouts */
|
|
iov_iter_iovec_advance(i, size);
|
|
} else if (iov_iter_is_bvec(i)) {
|
|
iov_iter_bvec_advance(i, size);
|
|
} else if (iov_iter_is_folioq(i)) {
|
|
iov_iter_folioq_advance(i, size);
|
|
} else if (iov_iter_is_discard(i)) {
|
|
i->count -= size;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_advance);
|
|
|
|
static void iov_iter_folioq_revert(struct iov_iter *i, size_t unroll)
|
|
{
|
|
const struct folio_queue *folioq = i->folioq;
|
|
unsigned int slot = i->folioq_slot;
|
|
|
|
for (;;) {
|
|
size_t fsize;
|
|
|
|
if (slot == 0) {
|
|
folioq = folioq->prev;
|
|
slot = folioq_nr_slots(folioq);
|
|
}
|
|
slot--;
|
|
|
|
fsize = folioq_folio_size(folioq, slot);
|
|
if (unroll <= fsize) {
|
|
i->iov_offset = fsize - unroll;
|
|
break;
|
|
}
|
|
unroll -= fsize;
|
|
}
|
|
|
|
i->folioq_slot = slot;
|
|
i->folioq = folioq;
|
|
}
|
|
|
|
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_discard(i)))
|
|
return;
|
|
if (unroll <= i->iov_offset) {
|
|
i->iov_offset -= unroll;
|
|
return;
|
|
}
|
|
unroll -= i->iov_offset;
|
|
if (iov_iter_is_xarray(i) || iter_is_ubuf(i)) {
|
|
BUG(); /* We should never go beyond the start of the specified
|
|
* range since we might then be straying into pages that
|
|
* aren't pinned.
|
|
*/
|
|
} else 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 if (iov_iter_is_folioq(i)) {
|
|
i->iov_offset = 0;
|
|
iov_iter_folioq_revert(i, unroll);
|
|
} else { /* same logics for iovec and kvec */
|
|
const struct iovec *iov = iter_iov(i);
|
|
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 (i->nr_segs > 1) {
|
|
if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i)))
|
|
return min(i->count, iter_iov(i)->iov_len - i->iov_offset);
|
|
if (iov_iter_is_bvec(i))
|
|
return min(i->count, i->bvec->bv_len - i->iov_offset);
|
|
}
|
|
if (unlikely(iov_iter_is_folioq(i)))
|
|
return !i->count ? 0 :
|
|
umin(folioq_folio_size(i->folioq, i->folioq_slot), i->count);
|
|
return i->count;
|
|
}
|
|
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 = (struct iov_iter){
|
|
.iter_type = ITER_KVEC,
|
|
.data_source = direction,
|
|
.kvec = kvec,
|
|
.nr_segs = nr_segs,
|
|
.iov_offset = 0,
|
|
.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 = (struct iov_iter){
|
|
.iter_type = ITER_BVEC,
|
|
.data_source = direction,
|
|
.bvec = bvec,
|
|
.nr_segs = nr_segs,
|
|
.iov_offset = 0,
|
|
.count = count
|
|
};
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_bvec);
|
|
|
|
/**
|
|
* iov_iter_folio_queue - Initialise an I/O iterator to use the folios in a folio queue
|
|
* @i: The iterator to initialise.
|
|
* @direction: The direction of the transfer.
|
|
* @folioq: The starting point in the folio queue.
|
|
* @first_slot: The first slot in the folio queue to use
|
|
* @offset: The offset into the folio in the first slot to start at
|
|
* @count: The size of the I/O buffer in bytes.
|
|
*
|
|
* Set up an I/O iterator to either draw data out of the pages attached to an
|
|
* inode or to inject data into those pages. The pages *must* be prevented
|
|
* from evaporation, either by taking a ref on them or locking them by the
|
|
* caller.
|
|
*/
|
|
void iov_iter_folio_queue(struct iov_iter *i, unsigned int direction,
|
|
const struct folio_queue *folioq, unsigned int first_slot,
|
|
unsigned int offset, size_t count)
|
|
{
|
|
BUG_ON(direction & ~1);
|
|
*i = (struct iov_iter) {
|
|
.iter_type = ITER_FOLIOQ,
|
|
.data_source = direction,
|
|
.folioq = folioq,
|
|
.folioq_slot = first_slot,
|
|
.count = count,
|
|
.iov_offset = offset,
|
|
};
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_folio_queue);
|
|
|
|
/**
|
|
* iov_iter_xarray - Initialise an I/O iterator to use the pages in an xarray
|
|
* @i: The iterator to initialise.
|
|
* @direction: The direction of the transfer.
|
|
* @xarray: The xarray to access.
|
|
* @start: The start file position.
|
|
* @count: The size of the I/O buffer in bytes.
|
|
*
|
|
* Set up an I/O iterator to either draw data out of the pages attached to an
|
|
* inode or to inject data into those pages. The pages *must* be prevented
|
|
* from evaporation, either by taking a ref on them or locking them by the
|
|
* caller.
|
|
*/
|
|
void iov_iter_xarray(struct iov_iter *i, unsigned int direction,
|
|
struct xarray *xarray, loff_t start, size_t count)
|
|
{
|
|
BUG_ON(direction & ~1);
|
|
*i = (struct iov_iter) {
|
|
.iter_type = ITER_XARRAY,
|
|
.data_source = direction,
|
|
.xarray = xarray,
|
|
.xarray_start = start,
|
|
.count = count,
|
|
.iov_offset = 0
|
|
};
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_xarray);
|
|
|
|
/**
|
|
* 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 = (struct iov_iter){
|
|
.iter_type = ITER_DISCARD,
|
|
.data_source = false,
|
|
.count = count,
|
|
.iov_offset = 0
|
|
};
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_discard);
|
|
|
|
static bool iov_iter_aligned_iovec(const struct iov_iter *i, unsigned addr_mask,
|
|
unsigned len_mask)
|
|
{
|
|
const struct iovec *iov = iter_iov(i);
|
|
size_t size = i->count;
|
|
size_t skip = i->iov_offset;
|
|
|
|
do {
|
|
size_t len = iov->iov_len - skip;
|
|
|
|
if (len > size)
|
|
len = size;
|
|
if (len & len_mask)
|
|
return false;
|
|
if ((unsigned long)(iov->iov_base + skip) & addr_mask)
|
|
return false;
|
|
|
|
iov++;
|
|
size -= len;
|
|
skip = 0;
|
|
} while (size);
|
|
|
|
return true;
|
|
}
|
|
|
|
static bool iov_iter_aligned_bvec(const struct iov_iter *i, unsigned addr_mask,
|
|
unsigned len_mask)
|
|
{
|
|
const struct bio_vec *bvec = i->bvec;
|
|
unsigned skip = i->iov_offset;
|
|
size_t size = i->count;
|
|
|
|
do {
|
|
size_t len = bvec->bv_len;
|
|
|
|
if (len > size)
|
|
len = size;
|
|
if (len & len_mask)
|
|
return false;
|
|
if ((unsigned long)(bvec->bv_offset + skip) & addr_mask)
|
|
return false;
|
|
|
|
bvec++;
|
|
size -= len;
|
|
skip = 0;
|
|
} while (size);
|
|
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* iov_iter_is_aligned() - Check if the addresses and lengths of each segments
|
|
* are aligned to the parameters.
|
|
*
|
|
* @i: &struct iov_iter to restore
|
|
* @addr_mask: bit mask to check against the iov element's addresses
|
|
* @len_mask: bit mask to check against the iov element's lengths
|
|
*
|
|
* Return: false if any addresses or lengths intersect with the provided masks
|
|
*/
|
|
bool iov_iter_is_aligned(const struct iov_iter *i, unsigned addr_mask,
|
|
unsigned len_mask)
|
|
{
|
|
if (likely(iter_is_ubuf(i))) {
|
|
if (i->count & len_mask)
|
|
return false;
|
|
if ((unsigned long)(i->ubuf + i->iov_offset) & addr_mask)
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i)))
|
|
return iov_iter_aligned_iovec(i, addr_mask, len_mask);
|
|
|
|
if (iov_iter_is_bvec(i))
|
|
return iov_iter_aligned_bvec(i, addr_mask, len_mask);
|
|
|
|
/* With both xarray and folioq types, we're dealing with whole folios. */
|
|
if (iov_iter_is_xarray(i)) {
|
|
if (i->count & len_mask)
|
|
return false;
|
|
if ((i->xarray_start + i->iov_offset) & addr_mask)
|
|
return false;
|
|
}
|
|
if (iov_iter_is_folioq(i)) {
|
|
if (i->count & len_mask)
|
|
return false;
|
|
if (i->iov_offset & addr_mask)
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
EXPORT_SYMBOL_GPL(iov_iter_is_aligned);
|
|
|
|
static unsigned long iov_iter_alignment_iovec(const struct iov_iter *i)
|
|
{
|
|
const struct iovec *iov = iter_iov(i);
|
|
unsigned long res = 0;
|
|
size_t size = i->count;
|
|
size_t skip = i->iov_offset;
|
|
|
|
do {
|
|
size_t len = iov->iov_len - skip;
|
|
if (len) {
|
|
res |= (unsigned long)iov->iov_base + skip;
|
|
if (len > size)
|
|
len = size;
|
|
res |= len;
|
|
size -= len;
|
|
}
|
|
iov++;
|
|
skip = 0;
|
|
} while (size);
|
|
return res;
|
|
}
|
|
|
|
static unsigned long iov_iter_alignment_bvec(const struct iov_iter *i)
|
|
{
|
|
const struct bio_vec *bvec = i->bvec;
|
|
unsigned res = 0;
|
|
size_t size = i->count;
|
|
unsigned skip = i->iov_offset;
|
|
|
|
do {
|
|
size_t len = bvec->bv_len - skip;
|
|
res |= (unsigned long)bvec->bv_offset + skip;
|
|
if (len > size)
|
|
len = size;
|
|
res |= len;
|
|
bvec++;
|
|
size -= len;
|
|
skip = 0;
|
|
} while (size);
|
|
|
|
return res;
|
|
}
|
|
|
|
unsigned long iov_iter_alignment(const struct iov_iter *i)
|
|
{
|
|
if (likely(iter_is_ubuf(i))) {
|
|
size_t size = i->count;
|
|
if (size)
|
|
return ((unsigned long)i->ubuf + i->iov_offset) | size;
|
|
return 0;
|
|
}
|
|
|
|
/* iovec and kvec have identical layouts */
|
|
if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i)))
|
|
return iov_iter_alignment_iovec(i);
|
|
|
|
if (iov_iter_is_bvec(i))
|
|
return iov_iter_alignment_bvec(i);
|
|
|
|
/* With both xarray and folioq types, we're dealing with whole folios. */
|
|
if (iov_iter_is_folioq(i))
|
|
return i->iov_offset | i->count;
|
|
if (iov_iter_is_xarray(i))
|
|
return (i->xarray_start + i->iov_offset) | i->count;
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_alignment);
|
|
|
|
unsigned long iov_iter_gap_alignment(const struct iov_iter *i)
|
|
{
|
|
unsigned long res = 0;
|
|
unsigned long v = 0;
|
|
size_t size = i->count;
|
|
unsigned k;
|
|
|
|
if (iter_is_ubuf(i))
|
|
return 0;
|
|
|
|
if (WARN_ON(!iter_is_iovec(i)))
|
|
return ~0U;
|
|
|
|
for (k = 0; k < i->nr_segs; k++) {
|
|
const struct iovec *iov = iter_iov(i) + k;
|
|
if (iov->iov_len) {
|
|
unsigned long base = (unsigned long)iov->iov_base;
|
|
if (v) // if not the first one
|
|
res |= base | v; // this start | previous end
|
|
v = base + iov->iov_len;
|
|
if (size <= iov->iov_len)
|
|
break;
|
|
size -= iov->iov_len;
|
|
}
|
|
}
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_gap_alignment);
|
|
|
|
static int want_pages_array(struct page ***res, size_t size,
|
|
size_t start, unsigned int maxpages)
|
|
{
|
|
unsigned int count = DIV_ROUND_UP(size + start, PAGE_SIZE);
|
|
|
|
if (count > maxpages)
|
|
count = maxpages;
|
|
WARN_ON(!count); // caller should've prevented that
|
|
if (!*res) {
|
|
*res = kvmalloc_array(count, sizeof(struct page *), GFP_KERNEL);
|
|
if (!*res)
|
|
return 0;
|
|
}
|
|
return count;
|
|
}
|
|
|
|
static ssize_t iter_folioq_get_pages(struct iov_iter *iter,
|
|
struct page ***ppages, size_t maxsize,
|
|
unsigned maxpages, size_t *_start_offset)
|
|
{
|
|
const struct folio_queue *folioq = iter->folioq;
|
|
struct page **pages;
|
|
unsigned int slot = iter->folioq_slot;
|
|
size_t extracted = 0, count = iter->count, iov_offset = iter->iov_offset;
|
|
|
|
if (slot >= folioq_nr_slots(folioq)) {
|
|
folioq = folioq->next;
|
|
slot = 0;
|
|
if (WARN_ON(iov_offset != 0))
|
|
return -EIO;
|
|
}
|
|
|
|
maxpages = want_pages_array(ppages, maxsize, iov_offset & ~PAGE_MASK, maxpages);
|
|
if (!maxpages)
|
|
return -ENOMEM;
|
|
*_start_offset = iov_offset & ~PAGE_MASK;
|
|
pages = *ppages;
|
|
|
|
for (;;) {
|
|
struct folio *folio = folioq_folio(folioq, slot);
|
|
size_t offset = iov_offset, fsize = folioq_folio_size(folioq, slot);
|
|
size_t part = PAGE_SIZE - offset % PAGE_SIZE;
|
|
|
|
if (offset < fsize) {
|
|
part = umin(part, umin(maxsize - extracted, fsize - offset));
|
|
count -= part;
|
|
iov_offset += part;
|
|
extracted += part;
|
|
|
|
*pages = folio_page(folio, offset / PAGE_SIZE);
|
|
get_page(*pages);
|
|
pages++;
|
|
maxpages--;
|
|
}
|
|
|
|
if (maxpages == 0 || extracted >= maxsize)
|
|
break;
|
|
|
|
if (iov_offset >= fsize) {
|
|
iov_offset = 0;
|
|
slot++;
|
|
if (slot == folioq_nr_slots(folioq) && folioq->next) {
|
|
folioq = folioq->next;
|
|
slot = 0;
|
|
}
|
|
}
|
|
}
|
|
|
|
iter->count = count;
|
|
iter->iov_offset = iov_offset;
|
|
iter->folioq = folioq;
|
|
iter->folioq_slot = slot;
|
|
return extracted;
|
|
}
|
|
|
|
static ssize_t iter_xarray_populate_pages(struct page **pages, struct xarray *xa,
|
|
pgoff_t index, unsigned int nr_pages)
|
|
{
|
|
XA_STATE(xas, xa, index);
|
|
struct page *page;
|
|
unsigned int ret = 0;
|
|
|
|
rcu_read_lock();
|
|
for (page = xas_load(&xas); page; page = xas_next(&xas)) {
|
|
if (xas_retry(&xas, page))
|
|
continue;
|
|
|
|
/* Has the page moved or been split? */
|
|
if (unlikely(page != xas_reload(&xas))) {
|
|
xas_reset(&xas);
|
|
continue;
|
|
}
|
|
|
|
pages[ret] = find_subpage(page, xas.xa_index);
|
|
get_page(pages[ret]);
|
|
if (++ret == nr_pages)
|
|
break;
|
|
}
|
|
rcu_read_unlock();
|
|
return ret;
|
|
}
|
|
|
|
static ssize_t iter_xarray_get_pages(struct iov_iter *i,
|
|
struct page ***pages, size_t maxsize,
|
|
unsigned maxpages, size_t *_start_offset)
|
|
{
|
|
unsigned nr, offset, count;
|
|
pgoff_t index;
|
|
loff_t pos;
|
|
|
|
pos = i->xarray_start + i->iov_offset;
|
|
index = pos >> PAGE_SHIFT;
|
|
offset = pos & ~PAGE_MASK;
|
|
*_start_offset = offset;
|
|
|
|
count = want_pages_array(pages, maxsize, offset, maxpages);
|
|
if (!count)
|
|
return -ENOMEM;
|
|
nr = iter_xarray_populate_pages(*pages, i->xarray, index, count);
|
|
if (nr == 0)
|
|
return 0;
|
|
|
|
maxsize = min_t(size_t, nr * PAGE_SIZE - offset, maxsize);
|
|
i->iov_offset += maxsize;
|
|
i->count -= maxsize;
|
|
return maxsize;
|
|
}
|
|
|
|
/* must be done on non-empty ITER_UBUF or ITER_IOVEC one */
|
|
static unsigned long first_iovec_segment(const struct iov_iter *i, size_t *size)
|
|
{
|
|
size_t skip;
|
|
long k;
|
|
|
|
if (iter_is_ubuf(i))
|
|
return (unsigned long)i->ubuf + i->iov_offset;
|
|
|
|
for (k = 0, skip = i->iov_offset; k < i->nr_segs; k++, skip = 0) {
|
|
const struct iovec *iov = iter_iov(i) + k;
|
|
size_t len = iov->iov_len - skip;
|
|
|
|
if (unlikely(!len))
|
|
continue;
|
|
if (*size > len)
|
|
*size = len;
|
|
return (unsigned long)iov->iov_base + skip;
|
|
}
|
|
BUG(); // if it had been empty, we wouldn't get called
|
|
}
|
|
|
|
/* must be done on non-empty ITER_BVEC one */
|
|
static struct page *first_bvec_segment(const struct iov_iter *i,
|
|
size_t *size, size_t *start)
|
|
{
|
|
struct page *page;
|
|
size_t skip = i->iov_offset, len;
|
|
|
|
len = i->bvec->bv_len - skip;
|
|
if (*size > len)
|
|
*size = len;
|
|
skip += i->bvec->bv_offset;
|
|
page = i->bvec->bv_page + skip / PAGE_SIZE;
|
|
*start = skip % PAGE_SIZE;
|
|
return page;
|
|
}
|
|
|
|
static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i,
|
|
struct page ***pages, size_t maxsize,
|
|
unsigned int maxpages, size_t *start)
|
|
{
|
|
unsigned int n, gup_flags = 0;
|
|
|
|
if (maxsize > i->count)
|
|
maxsize = i->count;
|
|
if (!maxsize)
|
|
return 0;
|
|
if (maxsize > MAX_RW_COUNT)
|
|
maxsize = MAX_RW_COUNT;
|
|
|
|
if (likely(user_backed_iter(i))) {
|
|
unsigned long addr;
|
|
int res;
|
|
|
|
if (iov_iter_rw(i) != WRITE)
|
|
gup_flags |= FOLL_WRITE;
|
|
if (i->nofault)
|
|
gup_flags |= FOLL_NOFAULT;
|
|
|
|
addr = first_iovec_segment(i, &maxsize);
|
|
*start = addr % PAGE_SIZE;
|
|
addr &= PAGE_MASK;
|
|
n = want_pages_array(pages, maxsize, *start, maxpages);
|
|
if (!n)
|
|
return -ENOMEM;
|
|
res = get_user_pages_fast(addr, n, gup_flags, *pages);
|
|
if (unlikely(res <= 0))
|
|
return res;
|
|
maxsize = min_t(size_t, maxsize, res * PAGE_SIZE - *start);
|
|
iov_iter_advance(i, maxsize);
|
|
return maxsize;
|
|
}
|
|
if (iov_iter_is_bvec(i)) {
|
|
struct page **p;
|
|
struct page *page;
|
|
|
|
page = first_bvec_segment(i, &maxsize, start);
|
|
n = want_pages_array(pages, maxsize, *start, maxpages);
|
|
if (!n)
|
|
return -ENOMEM;
|
|
p = *pages;
|
|
for (int k = 0; k < n; k++)
|
|
get_page(p[k] = page + k);
|
|
maxsize = min_t(size_t, maxsize, n * PAGE_SIZE - *start);
|
|
i->count -= maxsize;
|
|
i->iov_offset += maxsize;
|
|
if (i->iov_offset == i->bvec->bv_len) {
|
|
i->iov_offset = 0;
|
|
i->bvec++;
|
|
i->nr_segs--;
|
|
}
|
|
return maxsize;
|
|
}
|
|
if (iov_iter_is_folioq(i))
|
|
return iter_folioq_get_pages(i, pages, maxsize, maxpages, start);
|
|
if (iov_iter_is_xarray(i))
|
|
return iter_xarray_get_pages(i, pages, maxsize, maxpages, start);
|
|
return -EFAULT;
|
|
}
|
|
|
|
ssize_t iov_iter_get_pages2(struct iov_iter *i, struct page **pages,
|
|
size_t maxsize, unsigned maxpages, size_t *start)
|
|
{
|
|
if (!maxpages)
|
|
return 0;
|
|
BUG_ON(!pages);
|
|
|
|
return __iov_iter_get_pages_alloc(i, &pages, maxsize, maxpages, start);
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_get_pages2);
|
|
|
|
ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i,
|
|
struct page ***pages, size_t maxsize, size_t *start)
|
|
{
|
|
ssize_t len;
|
|
|
|
*pages = NULL;
|
|
|
|
len = __iov_iter_get_pages_alloc(i, pages, maxsize, ~0U, start);
|
|
if (len <= 0) {
|
|
kvfree(*pages);
|
|
*pages = NULL;
|
|
}
|
|
return len;
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_get_pages_alloc2);
|
|
|
|
static int iov_npages(const struct iov_iter *i, int maxpages)
|
|
{
|
|
size_t skip = i->iov_offset, size = i->count;
|
|
const struct iovec *p;
|
|
int npages = 0;
|
|
|
|
for (p = iter_iov(i); size; skip = 0, p++) {
|
|
unsigned offs = offset_in_page(p->iov_base + skip);
|
|
size_t len = min(p->iov_len - skip, size);
|
|
|
|
if (len) {
|
|
size -= len;
|
|
npages += DIV_ROUND_UP(offs + len, PAGE_SIZE);
|
|
if (unlikely(npages > maxpages))
|
|
return maxpages;
|
|
}
|
|
}
|
|
return npages;
|
|
}
|
|
|
|
static int bvec_npages(const struct iov_iter *i, int maxpages)
|
|
{
|
|
size_t skip = i->iov_offset, size = i->count;
|
|
const struct bio_vec *p;
|
|
int npages = 0;
|
|
|
|
for (p = i->bvec; size; skip = 0, p++) {
|
|
unsigned offs = (p->bv_offset + skip) % PAGE_SIZE;
|
|
size_t len = min(p->bv_len - skip, size);
|
|
|
|
size -= len;
|
|
npages += DIV_ROUND_UP(offs + len, PAGE_SIZE);
|
|
if (unlikely(npages > maxpages))
|
|
return maxpages;
|
|
}
|
|
return npages;
|
|
}
|
|
|
|
int iov_iter_npages(const struct iov_iter *i, int maxpages)
|
|
{
|
|
if (unlikely(!i->count))
|
|
return 0;
|
|
if (likely(iter_is_ubuf(i))) {
|
|
unsigned offs = offset_in_page(i->ubuf + i->iov_offset);
|
|
int npages = DIV_ROUND_UP(offs + i->count, PAGE_SIZE);
|
|
return min(npages, maxpages);
|
|
}
|
|
/* iovec and kvec have identical layouts */
|
|
if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i)))
|
|
return iov_npages(i, maxpages);
|
|
if (iov_iter_is_bvec(i))
|
|
return bvec_npages(i, maxpages);
|
|
if (iov_iter_is_folioq(i)) {
|
|
unsigned offset = i->iov_offset % PAGE_SIZE;
|
|
int npages = DIV_ROUND_UP(offset + i->count, PAGE_SIZE);
|
|
return min(npages, maxpages);
|
|
}
|
|
if (iov_iter_is_xarray(i)) {
|
|
unsigned offset = (i->xarray_start + i->iov_offset) % PAGE_SIZE;
|
|
int npages = DIV_ROUND_UP(offset + i->count, PAGE_SIZE);
|
|
return min(npages, maxpages);
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(iov_iter_npages);
|
|
|
|
const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags)
|
|
{
|
|
*new = *old;
|
|
if (iov_iter_is_bvec(new))
|
|
return new->bvec = kmemdup(new->bvec,
|
|
new->nr_segs * sizeof(struct bio_vec),
|
|
flags);
|
|
else if (iov_iter_is_kvec(new) || iter_is_iovec(new))
|
|
/* iovec and kvec have identical layout */
|
|
return new->__iov = kmemdup(new->__iov,
|
|
new->nr_segs * sizeof(struct iovec),
|
|
flags);
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL(dup_iter);
|
|
|
|
static __noclone int copy_compat_iovec_from_user(struct iovec *iov,
|
|
const struct iovec __user *uvec, u32 nr_segs)
|
|
{
|
|
const struct compat_iovec __user *uiov =
|
|
(const struct compat_iovec __user *)uvec;
|
|
int ret = -EFAULT;
|
|
u32 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 __noclone int copy_iovec_from_user(struct iovec *iov,
|
|
const struct iovec __user *uiov, unsigned long nr_segs)
|
|
{
|
|
int ret = -EFAULT;
|
|
|
|
if (!user_access_begin(uiov, nr_segs * sizeof(*uiov)))
|
|
return -EFAULT;
|
|
|
|
do {
|
|
void __user *buf;
|
|
ssize_t len;
|
|
|
|
unsafe_get_user(len, &uiov->iov_len, uaccess_end);
|
|
unsafe_get_user(buf, &uiov->iov_base, uaccess_end);
|
|
|
|
/* check for size_t not fitting in ssize_t .. */
|
|
if (unlikely(len < 0)) {
|
|
ret = -EINVAL;
|
|
goto uaccess_end;
|
|
}
|
|
iov->iov_base = buf;
|
|
iov->iov_len = len;
|
|
|
|
uiov++; iov++;
|
|
} while (--nr_segs);
|
|
|
|
ret = 0;
|
|
uaccess_end:
|
|
user_access_end();
|
|
return ret;
|
|
}
|
|
|
|
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 (unlikely(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;
|
|
}
|
|
|
|
/*
|
|
* Single segment iovec supplied by the user, import it as ITER_UBUF.
|
|
*/
|
|
static ssize_t __import_iovec_ubuf(int type, const struct iovec __user *uvec,
|
|
struct iovec **iovp, struct iov_iter *i,
|
|
bool compat)
|
|
{
|
|
struct iovec *iov = *iovp;
|
|
ssize_t ret;
|
|
|
|
if (compat)
|
|
ret = copy_compat_iovec_from_user(iov, uvec, 1);
|
|
else
|
|
ret = copy_iovec_from_user(iov, uvec, 1);
|
|
if (unlikely(ret))
|
|
return ret;
|
|
|
|
ret = import_ubuf(type, iov->iov_base, iov->iov_len, i);
|
|
if (unlikely(ret))
|
|
return ret;
|
|
*iovp = NULL;
|
|
return i->count;
|
|
}
|
|
|
|
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;
|
|
|
|
if (nr_segs == 1)
|
|
return __import_iovec_ubuf(type, uvec, iovp, i, compat);
|
|
|
|
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_ubuf(int rw, void __user *buf, size_t len, struct iov_iter *i)
|
|
{
|
|
if (len > MAX_RW_COUNT)
|
|
len = MAX_RW_COUNT;
|
|
if (unlikely(!access_ok(buf, len)))
|
|
return -EFAULT;
|
|
|
|
iov_iter_ubuf(i, rw, buf, len);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(import_ubuf);
|
|
|
|
/**
|
|
* iov_iter_restore() - Restore a &struct iov_iter to the same state as when
|
|
* iov_iter_save_state() was called.
|
|
*
|
|
* @i: &struct iov_iter to restore
|
|
* @state: state to restore from
|
|
*
|
|
* Used after iov_iter_save_state() to bring restore @i, if operations may
|
|
* have advanced it.
|
|
*
|
|
* Note: only works on ITER_IOVEC, ITER_BVEC, and ITER_KVEC
|
|
*/
|
|
void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state)
|
|
{
|
|
if (WARN_ON_ONCE(!iov_iter_is_bvec(i) && !iter_is_iovec(i) &&
|
|
!iter_is_ubuf(i)) && !iov_iter_is_kvec(i))
|
|
return;
|
|
i->iov_offset = state->iov_offset;
|
|
i->count = state->count;
|
|
if (iter_is_ubuf(i))
|
|
return;
|
|
/*
|
|
* For the *vec iters, nr_segs + iov is constant - if we increment
|
|
* the vec, then we also decrement the nr_segs count. Hence we don't
|
|
* need to track both of these, just one is enough and we can deduct
|
|
* the other from that. ITER_KVEC and ITER_IOVEC are the same struct
|
|
* size, so we can just increment the iov pointer as they are unionzed.
|
|
* ITER_BVEC _may_ be the same size on some archs, but on others it is
|
|
* not. Be safe and handle it separately.
|
|
*/
|
|
BUILD_BUG_ON(sizeof(struct iovec) != sizeof(struct kvec));
|
|
if (iov_iter_is_bvec(i))
|
|
i->bvec -= state->nr_segs - i->nr_segs;
|
|
else
|
|
i->__iov -= state->nr_segs - i->nr_segs;
|
|
i->nr_segs = state->nr_segs;
|
|
}
|
|
|
|
/*
|
|
* Extract a list of contiguous pages from an ITER_FOLIOQ iterator. This does
|
|
* not get references on the pages, nor does it get a pin on them.
|
|
*/
|
|
static ssize_t iov_iter_extract_folioq_pages(struct iov_iter *i,
|
|
struct page ***pages, size_t maxsize,
|
|
unsigned int maxpages,
|
|
iov_iter_extraction_t extraction_flags,
|
|
size_t *offset0)
|
|
{
|
|
const struct folio_queue *folioq = i->folioq;
|
|
struct page **p;
|
|
unsigned int nr = 0;
|
|
size_t extracted = 0, offset, slot = i->folioq_slot;
|
|
|
|
if (slot >= folioq_nr_slots(folioq)) {
|
|
folioq = folioq->next;
|
|
slot = 0;
|
|
if (WARN_ON(i->iov_offset != 0))
|
|
return -EIO;
|
|
}
|
|
|
|
offset = i->iov_offset & ~PAGE_MASK;
|
|
*offset0 = offset;
|
|
|
|
maxpages = want_pages_array(pages, maxsize, offset, maxpages);
|
|
if (!maxpages)
|
|
return -ENOMEM;
|
|
p = *pages;
|
|
|
|
for (;;) {
|
|
struct folio *folio = folioq_folio(folioq, slot);
|
|
size_t offset = i->iov_offset, fsize = folioq_folio_size(folioq, slot);
|
|
size_t part = PAGE_SIZE - offset % PAGE_SIZE;
|
|
|
|
if (offset < fsize) {
|
|
part = umin(part, umin(maxsize - extracted, fsize - offset));
|
|
i->count -= part;
|
|
i->iov_offset += part;
|
|
extracted += part;
|
|
|
|
p[nr++] = folio_page(folio, offset / PAGE_SIZE);
|
|
}
|
|
|
|
if (nr >= maxpages || extracted >= maxsize)
|
|
break;
|
|
|
|
if (i->iov_offset >= fsize) {
|
|
i->iov_offset = 0;
|
|
slot++;
|
|
if (slot == folioq_nr_slots(folioq) && folioq->next) {
|
|
folioq = folioq->next;
|
|
slot = 0;
|
|
}
|
|
}
|
|
}
|
|
|
|
i->folioq = folioq;
|
|
i->folioq_slot = slot;
|
|
return extracted;
|
|
}
|
|
|
|
/*
|
|
* Extract a list of contiguous pages from an ITER_XARRAY iterator. This does not
|
|
* get references on the pages, nor does it get a pin on them.
|
|
*/
|
|
static ssize_t iov_iter_extract_xarray_pages(struct iov_iter *i,
|
|
struct page ***pages, size_t maxsize,
|
|
unsigned int maxpages,
|
|
iov_iter_extraction_t extraction_flags,
|
|
size_t *offset0)
|
|
{
|
|
struct page *page, **p;
|
|
unsigned int nr = 0, offset;
|
|
loff_t pos = i->xarray_start + i->iov_offset;
|
|
pgoff_t index = pos >> PAGE_SHIFT;
|
|
XA_STATE(xas, i->xarray, index);
|
|
|
|
offset = pos & ~PAGE_MASK;
|
|
*offset0 = offset;
|
|
|
|
maxpages = want_pages_array(pages, maxsize, offset, maxpages);
|
|
if (!maxpages)
|
|
return -ENOMEM;
|
|
p = *pages;
|
|
|
|
rcu_read_lock();
|
|
for (page = xas_load(&xas); page; page = xas_next(&xas)) {
|
|
if (xas_retry(&xas, page))
|
|
continue;
|
|
|
|
/* Has the page moved or been split? */
|
|
if (unlikely(page != xas_reload(&xas))) {
|
|
xas_reset(&xas);
|
|
continue;
|
|
}
|
|
|
|
p[nr++] = find_subpage(page, xas.xa_index);
|
|
if (nr == maxpages)
|
|
break;
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
maxsize = min_t(size_t, nr * PAGE_SIZE - offset, maxsize);
|
|
iov_iter_advance(i, maxsize);
|
|
return maxsize;
|
|
}
|
|
|
|
/*
|
|
* Extract a list of contiguous pages from an ITER_BVEC iterator. This does
|
|
* not get references on the pages, nor does it get a pin on them.
|
|
*/
|
|
static ssize_t iov_iter_extract_bvec_pages(struct iov_iter *i,
|
|
struct page ***pages, size_t maxsize,
|
|
unsigned int maxpages,
|
|
iov_iter_extraction_t extraction_flags,
|
|
size_t *offset0)
|
|
{
|
|
struct page **p, *page;
|
|
size_t skip = i->iov_offset, offset, size;
|
|
int k;
|
|
|
|
for (;;) {
|
|
if (i->nr_segs == 0)
|
|
return 0;
|
|
size = min(maxsize, i->bvec->bv_len - skip);
|
|
if (size)
|
|
break;
|
|
i->iov_offset = 0;
|
|
i->nr_segs--;
|
|
i->bvec++;
|
|
skip = 0;
|
|
}
|
|
|
|
skip += i->bvec->bv_offset;
|
|
page = i->bvec->bv_page + skip / PAGE_SIZE;
|
|
offset = skip % PAGE_SIZE;
|
|
*offset0 = offset;
|
|
|
|
maxpages = want_pages_array(pages, size, offset, maxpages);
|
|
if (!maxpages)
|
|
return -ENOMEM;
|
|
p = *pages;
|
|
for (k = 0; k < maxpages; k++)
|
|
p[k] = page + k;
|
|
|
|
size = min_t(size_t, size, maxpages * PAGE_SIZE - offset);
|
|
iov_iter_advance(i, size);
|
|
return size;
|
|
}
|
|
|
|
/*
|
|
* Extract a list of virtually contiguous pages from an ITER_KVEC iterator.
|
|
* This does not get references on the pages, nor does it get a pin on them.
|
|
*/
|
|
static ssize_t iov_iter_extract_kvec_pages(struct iov_iter *i,
|
|
struct page ***pages, size_t maxsize,
|
|
unsigned int maxpages,
|
|
iov_iter_extraction_t extraction_flags,
|
|
size_t *offset0)
|
|
{
|
|
struct page **p, *page;
|
|
const void *kaddr;
|
|
size_t skip = i->iov_offset, offset, len, size;
|
|
int k;
|
|
|
|
for (;;) {
|
|
if (i->nr_segs == 0)
|
|
return 0;
|
|
size = min(maxsize, i->kvec->iov_len - skip);
|
|
if (size)
|
|
break;
|
|
i->iov_offset = 0;
|
|
i->nr_segs--;
|
|
i->kvec++;
|
|
skip = 0;
|
|
}
|
|
|
|
kaddr = i->kvec->iov_base + skip;
|
|
offset = (unsigned long)kaddr & ~PAGE_MASK;
|
|
*offset0 = offset;
|
|
|
|
maxpages = want_pages_array(pages, size, offset, maxpages);
|
|
if (!maxpages)
|
|
return -ENOMEM;
|
|
p = *pages;
|
|
|
|
kaddr -= offset;
|
|
len = offset + size;
|
|
for (k = 0; k < maxpages; k++) {
|
|
size_t seg = min_t(size_t, len, PAGE_SIZE);
|
|
|
|
if (is_vmalloc_or_module_addr(kaddr))
|
|
page = vmalloc_to_page(kaddr);
|
|
else
|
|
page = virt_to_page(kaddr);
|
|
|
|
p[k] = page;
|
|
len -= seg;
|
|
kaddr += PAGE_SIZE;
|
|
}
|
|
|
|
size = min_t(size_t, size, maxpages * PAGE_SIZE - offset);
|
|
iov_iter_advance(i, size);
|
|
return size;
|
|
}
|
|
|
|
/*
|
|
* Extract a list of contiguous pages from a user iterator and get a pin on
|
|
* each of them. This should only be used if the iterator is user-backed
|
|
* (IOBUF/UBUF).
|
|
*
|
|
* It does not get refs on the pages, but the pages must be unpinned by the
|
|
* caller once the transfer is complete.
|
|
*
|
|
* This is safe to be used where background IO/DMA *is* going to be modifying
|
|
* the buffer; using a pin rather than a ref makes forces fork() to give the
|
|
* child a copy of the page.
|
|
*/
|
|
static ssize_t iov_iter_extract_user_pages(struct iov_iter *i,
|
|
struct page ***pages,
|
|
size_t maxsize,
|
|
unsigned int maxpages,
|
|
iov_iter_extraction_t extraction_flags,
|
|
size_t *offset0)
|
|
{
|
|
unsigned long addr;
|
|
unsigned int gup_flags = 0;
|
|
size_t offset;
|
|
int res;
|
|
|
|
if (i->data_source == ITER_DEST)
|
|
gup_flags |= FOLL_WRITE;
|
|
if (extraction_flags & ITER_ALLOW_P2PDMA)
|
|
gup_flags |= FOLL_PCI_P2PDMA;
|
|
if (i->nofault)
|
|
gup_flags |= FOLL_NOFAULT;
|
|
|
|
addr = first_iovec_segment(i, &maxsize);
|
|
*offset0 = offset = addr % PAGE_SIZE;
|
|
addr &= PAGE_MASK;
|
|
maxpages = want_pages_array(pages, maxsize, offset, maxpages);
|
|
if (!maxpages)
|
|
return -ENOMEM;
|
|
res = pin_user_pages_fast(addr, maxpages, gup_flags, *pages);
|
|
if (unlikely(res <= 0))
|
|
return res;
|
|
maxsize = min_t(size_t, maxsize, res * PAGE_SIZE - offset);
|
|
iov_iter_advance(i, maxsize);
|
|
return maxsize;
|
|
}
|
|
|
|
/**
|
|
* iov_iter_extract_pages - Extract a list of contiguous pages from an iterator
|
|
* @i: The iterator to extract from
|
|
* @pages: Where to return the list of pages
|
|
* @maxsize: The maximum amount of iterator to extract
|
|
* @maxpages: The maximum size of the list of pages
|
|
* @extraction_flags: Flags to qualify request
|
|
* @offset0: Where to return the starting offset into (*@pages)[0]
|
|
*
|
|
* Extract a list of contiguous pages from the current point of the iterator,
|
|
* advancing the iterator. The maximum number of pages and the maximum amount
|
|
* of page contents can be set.
|
|
*
|
|
* If *@pages is NULL, a page list will be allocated to the required size and
|
|
* *@pages will be set to its base. If *@pages is not NULL, it will be assumed
|
|
* that the caller allocated a page list at least @maxpages in size and this
|
|
* will be filled in.
|
|
*
|
|
* @extraction_flags can have ITER_ALLOW_P2PDMA set to request peer-to-peer DMA
|
|
* be allowed on the pages extracted.
|
|
*
|
|
* The iov_iter_extract_will_pin() function can be used to query how cleanup
|
|
* should be performed.
|
|
*
|
|
* Extra refs or pins on the pages may be obtained as follows:
|
|
*
|
|
* (*) If the iterator is user-backed (ITER_IOVEC/ITER_UBUF), pins will be
|
|
* added to the pages, but refs will not be taken.
|
|
* iov_iter_extract_will_pin() will return true.
|
|
*
|
|
* (*) If the iterator is ITER_KVEC, ITER_BVEC, ITER_FOLIOQ or ITER_XARRAY, the
|
|
* pages are merely listed; no extra refs or pins are obtained.
|
|
* iov_iter_extract_will_pin() will return 0.
|
|
*
|
|
* Note also:
|
|
*
|
|
* (*) Use with ITER_DISCARD is not supported as that has no content.
|
|
*
|
|
* On success, the function sets *@pages to the new pagelist, if allocated, and
|
|
* sets *offset0 to the offset into the first page.
|
|
*
|
|
* It may also return -ENOMEM and -EFAULT.
|
|
*/
|
|
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)
|
|
{
|
|
maxsize = min_t(size_t, min_t(size_t, maxsize, i->count), MAX_RW_COUNT);
|
|
if (!maxsize)
|
|
return 0;
|
|
|
|
if (likely(user_backed_iter(i)))
|
|
return iov_iter_extract_user_pages(i, pages, maxsize,
|
|
maxpages, extraction_flags,
|
|
offset0);
|
|
if (iov_iter_is_kvec(i))
|
|
return iov_iter_extract_kvec_pages(i, pages, maxsize,
|
|
maxpages, extraction_flags,
|
|
offset0);
|
|
if (iov_iter_is_bvec(i))
|
|
return iov_iter_extract_bvec_pages(i, pages, maxsize,
|
|
maxpages, extraction_flags,
|
|
offset0);
|
|
if (iov_iter_is_folioq(i))
|
|
return iov_iter_extract_folioq_pages(i, pages, maxsize,
|
|
maxpages, extraction_flags,
|
|
offset0);
|
|
if (iov_iter_is_xarray(i))
|
|
return iov_iter_extract_xarray_pages(i, pages, maxsize,
|
|
maxpages, extraction_flags,
|
|
offset0);
|
|
return -EFAULT;
|
|
}
|
|
EXPORT_SYMBOL_GPL(iov_iter_extract_pages);
|