summaryrefslogtreecommitdiff
path: root/lib/iov_iter.c
diff options
context:
space:
mode:
authorKefeng Wang <wangkefeng.wang@huawei.com>2023-04-17 12:53:23 +0800
committerAndrew Morton <akpm@linux-foundation.org>2023-05-02 17:21:50 -0700
commit245f0922689364b21163af4937a05ea0ba576fae (patch)
treec7eafb96828dd9a267c395d38f440a10773d5792 /lib/iov_iter.c
parent65f67a3e002f0e5ae84a65be915248d57d480060 (diff)
mm: hwpoison: coredump: support recovery from dump_user_range()
dump_user_range() is used to copy the user page to a coredump file, but if a hardware memory error occurred during copy, which called from __kernel_write_iter() in dump_user_range(), it crashes, CPU: 112 PID: 7014 Comm: mca-recover Not tainted 6.3.0-rc2 #425 pc : __memcpy+0x110/0x260 lr : _copy_from_iter+0x3bc/0x4c8 ... Call trace: __memcpy+0x110/0x260 copy_page_from_iter+0xcc/0x130 pipe_write+0x164/0x6d8 __kernel_write_iter+0x9c/0x210 dump_user_range+0xc8/0x1d8 elf_core_dump+0x308/0x368 do_coredump+0x2e8/0xa40 get_signal+0x59c/0x788 do_signal+0x118/0x1f8 do_notify_resume+0xf0/0x280 el0_da+0x130/0x138 el0t_64_sync_handler+0x68/0xc0 el0t_64_sync+0x188/0x190 Generally, the '->write_iter' of file ops will use copy_page_from_iter() and copy_page_from_iter_atomic(), change memcpy() to copy_mc_to_kernel() in both of them to handle #MC during source read, which stop coredump processing and kill the task instead of kernel panic, but the source address may not always a user address, so introduce a new copy_mc flag in struct iov_iter{} to indicate that the iter could do a safe memory copy, also introduce the helpers to set/cleck the flag, for now, it's only used in coredump's dump_user_range(), but it could expand to any other scenarios to fix the similar issue. Link: https://lkml.kernel.org/r/20230417045323.11054-1-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Christian Brauner <brauner@kernel.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Tong Tiangen <tongtiangen@huawei.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'lib/iov_iter.c')
-rw-r--r--lib/iov_iter.c17
1 files changed, 15 insertions, 2 deletions
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index c3dbe994112c..960223ed9199 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -434,6 +434,7 @@ void iov_iter_init(struct iov_iter *i, unsigned int direction,
WARN_ON(direction & ~(READ | WRITE));
*i = (struct iov_iter) {
.iter_type = ITER_IOVEC,
+ .copy_mc = false,
.nofault = false,
.user_backed = true,
.data_source = direction,
@@ -630,6 +631,14 @@ size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
EXPORT_SYMBOL_GPL(_copy_mc_to_iter);
#endif /* CONFIG_ARCH_HAS_COPY_MC */
+static void *memcpy_from_iter(struct iov_iter *i, void *to, const void *from,
+ size_t size)
+{
+ if (iov_iter_is_copy_mc(i))
+ return (void *)copy_mc_to_kernel(to, from, size);
+ return memcpy(to, from, size);
+}
+
size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
{
if (WARN_ON_ONCE(!i->data_source))
@@ -639,7 +648,7 @@ size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
might_fault();
iterate_and_advance(i, bytes, base, len, off,
copyin(addr + off, base, len),
- memcpy(addr + off, base, len)
+ memcpy_from_iter(i, addr + off, base, len)
)
return bytes;
@@ -862,7 +871,7 @@ size_t copy_page_from_iter_atomic(struct page *page, unsigned offset, size_t byt
}
iterate_and_advance(i, bytes, base, len, off,
copyin(p + off, base, len),
- memcpy(p + off, base, len)
+ memcpy_from_iter(i, p + off, base, len)
)
kunmap_atomic(kaddr);
return bytes;
@@ -1043,6 +1052,7 @@ void iov_iter_kvec(struct iov_iter *i, unsigned int direction,
WARN_ON(direction & ~(READ | WRITE));
*i = (struct iov_iter){
.iter_type = ITER_KVEC,
+ .copy_mc = false,
.data_source = direction,
.kvec = kvec,
.nr_segs = nr_segs,
@@ -1059,6 +1069,7 @@ void iov_iter_bvec(struct iov_iter *i, unsigned int direction,
WARN_ON(direction & ~(READ | WRITE));
*i = (struct iov_iter){
.iter_type = ITER_BVEC,
+ .copy_mc = false,
.data_source = direction,
.bvec = bvec,
.nr_segs = nr_segs,
@@ -1105,6 +1116,7 @@ void iov_iter_xarray(struct iov_iter *i, unsigned int direction,
BUG_ON(direction & ~1);
*i = (struct iov_iter) {
.iter_type = ITER_XARRAY,
+ .copy_mc = false,
.data_source = direction,
.xarray = xarray,
.xarray_start = start,
@@ -1128,6 +1140,7 @@ 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,
+ .copy_mc = false,
.data_source = false,
.count = count,
.iov_offset = 0