[PATCH v2 1/4] mm: Introduce a 'min_size' argument to fault_in_*()
Catalin Marinas
catalin.marinas at arm.com
Wed Dec 1 11:37:47 PST 2021
There is no functional change after this patch as all callers pass a
min_size of 0. This argument will be used in subsequent patches to probe
for faults at sub-page granularity (e.g. arm64 MTE and SPARC ADI).
With a non-zero 'min_size' argument, the fault_in_*() functions return
the full range if they don't manage to fault in the minimum size.
Signed-off-by: Catalin Marinas <catalin.marinas at arm.com>
---
arch/powerpc/kernel/kvm.c | 2 +-
arch/powerpc/kernel/signal_32.c | 4 ++--
arch/powerpc/kernel/signal_64.c | 2 +-
arch/x86/kernel/fpu/signal.c | 2 +-
drivers/gpu/drm/armada/armada_gem.c | 2 +-
fs/btrfs/file.c | 6 ++---
fs/btrfs/ioctl.c | 2 +-
fs/f2fs/file.c | 2 +-
fs/fuse/file.c | 2 +-
fs/gfs2/file.c | 8 +++----
fs/iomap/buffered-io.c | 2 +-
fs/ntfs/file.c | 2 +-
fs/ntfs3/file.c | 2 +-
include/linux/pagemap.h | 8 ++++---
include/linux/uio.h | 6 +++--
lib/iov_iter.c | 28 +++++++++++++++++++-----
mm/filemap.c | 2 +-
mm/gup.c | 34 ++++++++++++++++++++---------
18 files changed, 75 insertions(+), 41 deletions(-)
diff --git a/arch/powerpc/kernel/kvm.c b/arch/powerpc/kernel/kvm.c
index 6568823cf306..7a7fb08df4c4 100644
--- a/arch/powerpc/kernel/kvm.c
+++ b/arch/powerpc/kernel/kvm.c
@@ -670,7 +670,7 @@ static void __init kvm_use_magic_page(void)
/* Quick self-test to see if the mapping works */
if (fault_in_readable((const char __user *)KVM_MAGIC_PAGE,
- sizeof(u32))) {
+ sizeof(u32), 0)) {
kvm_patching_worked = false;
return;
}
diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index 3e053e2fd6b6..7c817881d418 100644
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -1048,7 +1048,7 @@ SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx,
if (new_ctx == NULL)
return 0;
if (!access_ok(new_ctx, ctx_size) ||
- fault_in_readable((char __user *)new_ctx, ctx_size))
+ fault_in_readable((char __user *)new_ctx, ctx_size, 0))
return -EFAULT;
/*
@@ -1239,7 +1239,7 @@ SYSCALL_DEFINE3(debug_setcontext, struct ucontext __user *, ctx,
#endif
if (!access_ok(ctx, sizeof(*ctx)) ||
- fault_in_readable((char __user *)ctx, sizeof(*ctx)))
+ fault_in_readable((char __user *)ctx, sizeof(*ctx), 0))
return -EFAULT;
/*
diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index d1e1fc0acbea..732fa4e10d24 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -688,7 +688,7 @@ SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx,
if (new_ctx == NULL)
return 0;
if (!access_ok(new_ctx, ctx_size) ||
- fault_in_readable((char __user *)new_ctx, ctx_size))
+ fault_in_readable((char __user *)new_ctx, ctx_size, 0))
return -EFAULT;
/*
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
index d5958278eba6..c9bd217e3364 100644
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -309,7 +309,7 @@ static bool restore_fpregs_from_user(void __user *buf, u64 xrestore,
if (ret != X86_TRAP_PF)
return false;
- if (!fault_in_readable(buf, size))
+ if (!fault_in_readable(buf, size, 0))
goto retry;
return false;
}
diff --git a/drivers/gpu/drm/armada/armada_gem.c b/drivers/gpu/drm/armada/armada_gem.c
index 147abf1a3968..0f44219c0120 100644
--- a/drivers/gpu/drm/armada/armada_gem.c
+++ b/drivers/gpu/drm/armada/armada_gem.c
@@ -351,7 +351,7 @@ int armada_gem_pwrite_ioctl(struct drm_device *dev, void *data,
if (!access_ok(ptr, args->size))
return -EFAULT;
- if (fault_in_readable(ptr, args->size))
+ if (fault_in_readable(ptr, args->size, 0))
return -EFAULT;
dobj = armada_gem_object_lookup(file, args->handle);
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 11204dbbe053..96ac4b186b72 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1718,7 +1718,7 @@ static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb,
* Fault pages before locking them in prepare_pages
* to avoid recursive lock
*/
- if (unlikely(fault_in_iov_iter_readable(i, write_bytes))) {
+ if (unlikely(fault_in_iov_iter_readable(i, write_bytes, 0))) {
ret = -EFAULT;
break;
}
@@ -2021,7 +2021,7 @@ static ssize_t btrfs_direct_write(struct kiocb *iocb, struct iov_iter *from)
if (left == prev_left) {
err = -ENOTBLK;
} else {
- fault_in_iov_iter_readable(from, left);
+ fault_in_iov_iter_readable(from, left, 0);
prev_left = left;
goto again;
}
@@ -3772,7 +3772,7 @@ static ssize_t btrfs_direct_read(struct kiocb *iocb, struct iov_iter *to)
* the first time we are retrying. Fault in as many pages
* as possible and retry.
*/
- fault_in_iov_iter_writeable(to, left);
+ fault_in_iov_iter_writeable(to, left, 0);
prev_left = left;
goto again;
}
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 92138ac2a4e2..c7d74c8776a1 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2223,7 +2223,7 @@ static noinline int search_ioctl(struct inode *inode,
while (1) {
ret = -EFAULT;
- if (fault_in_writeable(ubuf + sk_offset, *buf_size - sk_offset))
+ if (fault_in_writeable(ubuf + sk_offset, *buf_size - sk_offset, 0))
break;
ret = btrfs_search_forward(root, &key, path, sk->min_transid);
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 92ec2699bc85..fb6eceac0d57 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -4276,7 +4276,7 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
size_t target_size = 0;
int err;
- if (fault_in_iov_iter_readable(from, iov_iter_count(from)))
+ if (fault_in_iov_iter_readable(from, iov_iter_count(from), 0))
set_inode_flag(inode, FI_NO_PREALLOC);
if ((iocb->ki_flags & IOCB_NOWAIT)) {
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 9d6c5f6361f7..c823b9f70215 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1162,7 +1162,7 @@ static ssize_t fuse_fill_write_pages(struct fuse_io_args *ia,
again:
err = -EFAULT;
- if (fault_in_iov_iter_readable(ii, bytes))
+ if (fault_in_iov_iter_readable(ii, bytes, 0))
break;
err = -ENOMEM;
diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index 3e718cfc19a7..f7bd3bfd0690 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -847,7 +847,7 @@ static ssize_t gfs2_file_direct_read(struct kiocb *iocb, struct iov_iter *to,
size_t leftover;
gfs2_holder_allow_demote(gh);
- leftover = fault_in_iov_iter_writeable(to, window_size);
+ leftover = fault_in_iov_iter_writeable(to, window_size, 0);
gfs2_holder_disallow_demote(gh);
if (leftover != window_size) {
if (!gfs2_holder_queued(gh))
@@ -916,7 +916,7 @@ static ssize_t gfs2_file_direct_write(struct kiocb *iocb, struct iov_iter *from,
size_t leftover;
gfs2_holder_allow_demote(gh);
- leftover = fault_in_iov_iter_readable(from, window_size);
+ leftover = fault_in_iov_iter_readable(from, window_size, 0);
gfs2_holder_disallow_demote(gh);
if (leftover != window_size) {
if (!gfs2_holder_queued(gh))
@@ -985,7 +985,7 @@ static ssize_t gfs2_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
size_t leftover;
gfs2_holder_allow_demote(&gh);
- leftover = fault_in_iov_iter_writeable(to, window_size);
+ leftover = fault_in_iov_iter_writeable(to, window_size, 0);
gfs2_holder_disallow_demote(&gh);
if (leftover != window_size) {
if (!gfs2_holder_queued(&gh)) {
@@ -1063,7 +1063,7 @@ static ssize_t gfs2_file_buffered_write(struct kiocb *iocb,
size_t leftover;
gfs2_holder_allow_demote(gh);
- leftover = fault_in_iov_iter_readable(from, window_size);
+ leftover = fault_in_iov_iter_readable(from, window_size, 0);
gfs2_holder_disallow_demote(gh);
if (leftover != window_size) {
from->count = min(from->count, window_size - leftover);
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 1753c26c8e76..e7a529405775 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -750,7 +750,7 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i)
* same page as we're writing to, without it being marked
* up-to-date.
*/
- if (unlikely(fault_in_iov_iter_readable(i, bytes))) {
+ if (unlikely(fault_in_iov_iter_readable(i, bytes, 0))) {
status = -EFAULT;
break;
}
diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c
index 2ae25e48a41a..441aeefda8b6 100644
--- a/fs/ntfs/file.c
+++ b/fs/ntfs/file.c
@@ -1830,7 +1830,7 @@ static ssize_t ntfs_perform_write(struct file *file, struct iov_iter *i,
* pages being swapped out between us bringing them into memory
* and doing the actual copying.
*/
- if (unlikely(fault_in_iov_iter_readable(i, bytes))) {
+ if (unlikely(fault_in_iov_iter_readable(i, bytes, 0))) {
status = -EFAULT;
break;
}
diff --git a/fs/ntfs3/file.c b/fs/ntfs3/file.c
index 787b53b984ee..208686bda052 100644
--- a/fs/ntfs3/file.c
+++ b/fs/ntfs3/file.c
@@ -990,7 +990,7 @@ static ssize_t ntfs_compress_write(struct kiocb *iocb, struct iov_iter *from)
frame_vbo = pos & ~(frame_size - 1);
index = frame_vbo >> PAGE_SHIFT;
- if (unlikely(fault_in_iov_iter_readable(from, bytes))) {
+ if (unlikely(fault_in_iov_iter_readable(from, bytes, 0))) {
err = -EFAULT;
goto out;
}
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 1a0c646eb6ff..79d328031247 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -909,9 +909,11 @@ void folio_add_wait_queue(struct folio *folio, wait_queue_entry_t *waiter);
/*
* Fault in userspace address range.
*/
-size_t fault_in_writeable(char __user *uaddr, size_t size);
-size_t fault_in_safe_writeable(const char __user *uaddr, size_t size);
-size_t fault_in_readable(const char __user *uaddr, size_t size);
+size_t fault_in_writeable(char __user *uaddr, size_t size, size_t min_size);
+size_t fault_in_safe_writeable(const char __user *uaddr, size_t size,
+ size_t min_size);
+size_t fault_in_readable(const char __user *uaddr, size_t size,
+ size_t min_size);
int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
pgoff_t index, gfp_t gfp);
diff --git a/include/linux/uio.h b/include/linux/uio.h
index 6350354f97e9..06c54c3ab3f8 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -134,8 +134,10 @@ size_t copy_page_from_iter_atomic(struct page *page, unsigned offset,
size_t bytes, struct iov_iter *i);
void iov_iter_advance(struct iov_iter *i, size_t bytes);
void iov_iter_revert(struct iov_iter *i, size_t bytes);
-size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t bytes);
-size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t bytes);
+size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t bytes,
+ size_t min_size);
+size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t bytes,
+ size_t min_size);
size_t iov_iter_single_seg_count(const struct iov_iter *i);
size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i);
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 66a740e6e153..ecb95bb5c423 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -191,7 +191,7 @@ static size_t copy_page_to_iter_iovec(struct page *page, size_t offset, size_t b
buf = iov->iov_base + skip;
copy = min(bytes, iov->iov_len - skip);
- if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_writeable(buf, copy)) {
+ if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_writeable(buf, copy, 0)) {
kaddr = kmap_atomic(page);
from = kaddr + offset;
@@ -275,7 +275,7 @@ static size_t copy_page_from_iter_iovec(struct page *page, size_t offset, size_t
buf = iov->iov_base + skip;
copy = min(bytes, iov->iov_len - skip);
- if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_readable(buf, copy)) {
+ if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_readable(buf, copy, 0)) {
kaddr = kmap_atomic(page);
to = kaddr + offset;
@@ -433,6 +433,7 @@ static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t by
* fault_in_iov_iter_readable - fault in iov iterator for reading
* @i: iterator
* @size: maximum length
+ * @min_size: minimum size to be faulted in
*
* Fault in one or more iovecs of the given iov_iter, to a maximum length of
* @size. For each iovec, fault in each page that constitutes the iovec.
@@ -442,25 +443,32 @@ static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t by
*
* Always returns 0 for non-userspace iterators.
*/
-size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t size)
+size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t size,
+ size_t min_size)
{
if (iter_is_iovec(i)) {
size_t count = min(size, iov_iter_count(i));
const struct iovec *p;
size_t skip;
+ size_t orig_size = size;
size -= count;
for (p = i->iov, skip = i->iov_offset; count; p++, skip = 0) {
size_t len = min(count, p->iov_len - skip);
+ size_t min_len = min(len, min_size);
size_t ret;
if (unlikely(!len))
continue;
- ret = fault_in_readable(p->iov_base + skip, len);
+ ret = fault_in_readable(p->iov_base + skip, len,
+ min_len);
count -= len - ret;
+ min_size -= min(min_size, len - ret);
if (ret)
break;
}
+ if (min_size)
+ return orig_size;
return count + size;
}
return 0;
@@ -471,6 +479,7 @@ EXPORT_SYMBOL(fault_in_iov_iter_readable);
* fault_in_iov_iter_writeable - fault in iov iterator for writing
* @i: iterator
* @size: maximum length
+ * @min_size: minimum size to be faulted in
*
* Faults in the iterator using get_user_pages(), i.e., without triggering
* hardware page faults. This is primarily useful when we already know that
@@ -481,25 +490,32 @@ EXPORT_SYMBOL(fault_in_iov_iter_readable);
*
* Always returns 0 for non-user-space iterators.
*/
-size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t size)
+size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t size,
+ size_t min_size)
{
if (iter_is_iovec(i)) {
size_t count = min(size, iov_iter_count(i));
const struct iovec *p;
size_t skip;
+ size_t orig_size = size;
size -= count;
for (p = i->iov, skip = i->iov_offset; count; p++, skip = 0) {
size_t len = min(count, p->iov_len - skip);
+ size_t min_len = min(len, min_size);
size_t ret;
if (unlikely(!len))
continue;
- ret = fault_in_safe_writeable(p->iov_base + skip, len);
+ ret = fault_in_safe_writeable(p->iov_base + skip, len,
+ min_len);
count -= len - ret;
+ min_size -= min(min_size, len - ret);
if (ret)
break;
}
+ if (min_size)
+ return orig_size;
return count + size;
}
return 0;
diff --git a/mm/filemap.c b/mm/filemap.c
index daa0e23a6ee6..e5d7f5b1e5cc 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3743,7 +3743,7 @@ ssize_t generic_perform_write(struct file *file,
* same page as we're writing to, without it being marked
* up-to-date.
*/
- if (unlikely(fault_in_iov_iter_readable(i, bytes))) {
+ if (unlikely(fault_in_iov_iter_readable(i, bytes, 0))) {
status = -EFAULT;
break;
}
diff --git a/mm/gup.c b/mm/gup.c
index 2c51e9748a6a..baa8240615a4 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1662,13 +1662,15 @@ static long __get_user_pages_locked(struct mm_struct *mm, unsigned long start,
* fault_in_writeable - fault in userspace address range for writing
* @uaddr: start of address range
* @size: size of address range
+ * @min_size: minimum size to be faulted in
*
* Returns the number of bytes not faulted in (like copy_to_user() and
* copy_from_user()).
*/
-size_t fault_in_writeable(char __user *uaddr, size_t size)
+size_t fault_in_writeable(char __user *uaddr, size_t size, size_t min_size)
{
char __user *start = uaddr, *end;
+ size_t faulted_in = size;
if (unlikely(size == 0))
return 0;
@@ -1688,8 +1690,10 @@ size_t fault_in_writeable(char __user *uaddr, size_t size)
out:
if (size > uaddr - start)
- return size - (uaddr - start);
- return 0;
+ faulted_in = uaddr - start;
+ if (faulted_in < min_size)
+ return size;
+ return size - faulted_in;
}
EXPORT_SYMBOL(fault_in_writeable);
@@ -1697,6 +1701,7 @@ EXPORT_SYMBOL(fault_in_writeable);
* fault_in_safe_writeable - fault in an address range for writing
* @uaddr: start of address range
* @size: length of address range
+ * @min_size: minimum size to be faulted in
*
* Faults in an address range using get_user_pages, i.e., without triggering
* hardware page faults. This is primarily useful when we already know that
@@ -1711,13 +1716,15 @@ EXPORT_SYMBOL(fault_in_writeable);
* Returns the number of bytes not faulted in, like copy_to_user() and
* copy_from_user().
*/
-size_t fault_in_safe_writeable(const char __user *uaddr, size_t size)
+size_t fault_in_safe_writeable(const char __user *uaddr, size_t size,
+ size_t min_size)
{
unsigned long start = (unsigned long)untagged_addr(uaddr);
unsigned long end, nstart, nend;
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma = NULL;
int locked = 0;
+ size_t faulted_in = size;
nstart = start & PAGE_MASK;
end = PAGE_ALIGN(start + size);
@@ -1750,9 +1757,11 @@ size_t fault_in_safe_writeable(const char __user *uaddr, size_t size)
}
if (locked)
mmap_read_unlock(mm);
- if (nstart == end)
- return 0;
- return size - min_t(size_t, nstart - start, size);
+ if (nstart != end)
+ faulted_in = min_t(size_t, nstart - start, size);
+ if (faulted_in < min_size)
+ return size;
+ return size - faulted_in;
}
EXPORT_SYMBOL(fault_in_safe_writeable);
@@ -1760,14 +1769,17 @@ EXPORT_SYMBOL(fault_in_safe_writeable);
* fault_in_readable - fault in userspace address range for reading
* @uaddr: start of user address range
* @size: size of user address range
+ * @min_size: minimum size to be faulted in
*
* Returns the number of bytes not faulted in (like copy_to_user() and
* copy_from_user()).
*/
-size_t fault_in_readable(const char __user *uaddr, size_t size)
+size_t fault_in_readable(const char __user *uaddr, size_t size,
+ size_t min_size)
{
const char __user *start = uaddr, *end;
volatile char c;
+ size_t faulted_in = size;
if (unlikely(size == 0))
return 0;
@@ -1788,8 +1800,10 @@ size_t fault_in_readable(const char __user *uaddr, size_t size)
out:
(void)c;
if (size > uaddr - start)
- return size - (uaddr - start);
- return 0;
+ faulted_in = uaddr - start;
+ if (faulted_in < min_size)
+ return size;
+ return size - faulted_in;
}
EXPORT_SYMBOL(fault_in_readable);
More information about the linux-arm-kernel
mailing list