#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 */
* 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
*/
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)