On Fri, Mar 08, 2019 at 12:53:21PM -0600, Josh Poimboeuf wrote: > On Thu, Mar 07, 2019 at 12:45:14PM +0100, Peter Zijlstra wrote: > > /* > > + * 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. > > + * > > + * Input: > > + * rdi destination > > + * rsi source > > + * rdx count > > + * > > + * Output: > > + * eax uncopied bytes or 0 if successful. > > + */ > > +ALIGN; > > +copy_user_handle_tail: > > + movl %edx,%ecx > > +1: rep movsb > > +2: mov %ecx,%eax > > + ASM_CLAC > > + ret > > + > > + _ASM_EXTABLE_UA(1b, 2b) > > +ENDPROC(copy_user_handle_tail) > > This is an unstructured piece of code rather than a callable function, > END would probably be more appropriate. Or maybe it should just be a > local label (.Lcopy_user_handle_tail) because I don't think the > alignment and ELF symbol size are even needed.
ENDPROC makes it STT_FUNC and gets us stricter AC tests.
