diff options
Diffstat (limited to 'arch/x86/lib')
| -rw-r--r-- | arch/x86/lib/copy_user_64.S | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/arch/x86/lib/copy_user_64.S b/arch/x86/lib/copy_user_64.S index 5b68e945bf65..77b9b2a3b5c8 100644 --- a/arch/x86/lib/copy_user_64.S +++ b/arch/x86/lib/copy_user_64.S @@ -15,6 +15,7 @@ #include <asm/asm.h> #include <asm/smap.h> #include <asm/export.h> +#include <asm/trapnr.h> .macro ALIGN_DESTINATION /* check for bad alignment of destination */ @@ -221,6 +222,7 @@ EXPORT_SYMBOL(copy_user_enhanced_fast_string) * Try to copy last bytes and clear the rest if needed. * Since protection fault in copy_from/to_user is not a normal situation, * it is not necessary to optimize tail handling. + * Don't try to copy the tail if machine check happened * * Input: * rdi destination @@ -232,11 +234,24 @@ EXPORT_SYMBOL(copy_user_enhanced_fast_string) */ SYM_CODE_START_LOCAL(.Lcopy_user_handle_tail) movl %edx,%ecx + cmp $X86_TRAP_MC,%eax /* check if X86_TRAP_MC */ + je 3f 1: rep movsb 2: mov %ecx,%eax ASM_CLAC ret + /* + * Return zero to pretend that this copy succeeded. This + * is counter-intuitive, but needed to prevent the code + * in lib/iov_iter.c from retrying and running back into + * the poison cache line again. The machine check handler + * will ensure that a SIGBUS is sent to the task. + */ +3: xorl %eax,%eax + ASM_CLAC + ret + _ASM_EXTABLE_CPY(1b, 2b) SYM_CODE_END(.Lcopy_user_handle_tail) |