diff options
Diffstat (limited to 'arch/x86/lib/copy_mc_64.S')
| -rw-r--r-- | arch/x86/lib/copy_mc_64.S | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/arch/x86/lib/copy_mc_64.S b/arch/x86/lib/copy_mc_64.S index c3b613c4544a..892d8915f609 100644 --- a/arch/x86/lib/copy_mc_64.S +++ b/arch/x86/lib/copy_mc_64.S @@ -124,4 +124,40 @@ EXPORT_SYMBOL_GPL(copy_mc_fragile) _ASM_EXTABLE(.L_write_words, .E_write_words) _ASM_EXTABLE(.L_write_trailing_bytes, .E_trailing_bytes) #endif /* CONFIG_X86_MCE */ + +/* + * copy_mc_enhanced_fast_string - memory copy with exception handling + * + * Fast string copy + fault / exception handling. If the CPU does + * support machine check exception recovery, but does not support + * recovering from fast-string exceptions then this CPU needs to be + * added to the copy_mc_fragile_key set of quirks. Otherwise, absent any + * machine check recovery support this version should be no slower than + * standard memcpy. + */ +SYM_FUNC_START(copy_mc_enhanced_fast_string) + movq %rdi, %rax + movq %rdx, %rcx +.L_copy: + rep movsb + /* Copy successful. Return zero */ + xorl %eax, %eax + ret +SYM_FUNC_END(copy_mc_enhanced_fast_string) + + .section .fixup, "ax" +.E_copy: + /* + * On fault %rcx is updated such that the copy instruction could + * optionally be restarted at the fault position, i.e. it + * contains 'bytes remaining'. A non-zero return indicates error + * to copy_mc_generic() users, or indicate short transfers to + * user-copy routines. + */ + movq %rcx, %rax + ret + + .previous + + _ASM_EXTABLE_FAULT(.L_copy, .E_copy) #endif /* !CONFIG_UML */ |