From 874b45a595aa6f6c009d5f9575d14df4823fa046 Mon Sep 17 00:00:00 2001 From: Kefeng Wang Date: Mon, 17 Apr 2023 12:53:23 +0800 Subject: [PATCH] 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 Cc: Alexander Viro Cc: Christian Brauner Cc: Miaohe Lin Cc: Naoya Horiguchi Cc: Tong Tiangen Cc: Jens Axboe Signed-off-by: Andrew Morton --- fs/coredump.c | 1 + include/linux/uio.h | 16 ++++++++++++++++ lib/iov_iter.c | 17 +++++++++++++++-- 3 files changed, 32 insertions(+), 2 deletions(-) diff --git a/fs/coredump.c b/fs/coredump.c index 5df1e6e1eb2bea..ece7badf701bc2 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -882,6 +882,7 @@ static int dump_emit_page(struct coredump_params *cprm, struct page *page) pos = file->f_pos; bvec_set_page(&bvec, page, PAGE_SIZE, 0); iov_iter_bvec(&iter, ITER_SOURCE, &bvec, 1, PAGE_SIZE); + iov_iter_set_copy_mc(&iter); n = __kernel_write_iter(cprm->file, &iter, &pos); if (n != PAGE_SIZE) return 0; diff --git a/include/linux/uio.h b/include/linux/uio.h index 29eb18bb6feb12..288ea7f8fd6f4c 100644 --- a/include/linux/uio.h +++ b/include/linux/uio.h @@ -42,6 +42,7 @@ struct iov_iter_state { struct iov_iter { u8 iter_type; + bool copy_mc; bool nofault; bool data_source; bool user_backed; @@ -234,8 +235,22 @@ size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i); #ifdef CONFIG_ARCH_HAS_COPY_MC size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i); +static inline void iov_iter_set_copy_mc(struct iov_iter *i) +{ + i->copy_mc = true; +} + +static inline bool iov_iter_is_copy_mc(const struct iov_iter *i) +{ + return i->copy_mc; +} #else #define _copy_mc_to_iter _copy_to_iter +static inline void iov_iter_set_copy_mc(struct iov_iter *i) { } +static inline bool iov_iter_is_copy_mc(const struct iov_iter *i) +{ + return false; +} #endif size_t iov_iter_zero(size_t bytes, struct iov_iter *); @@ -358,6 +373,7 @@ static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction, WARN_ON(direction & ~(READ | WRITE)); *i = (struct iov_iter) { .iter_type = ITER_UBUF, + .copy_mc = false, .user_backed = true, .data_source = direction, .ubuf = buf, diff --git a/lib/iov_iter.c b/lib/iov_iter.c index 34dd6bdf2fba3c..5f6da093553bff 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