Peter Zijlstra <peterz@xxxxxxxxxxxxx> writes:
> On Tue, Oct 29, 2024 at 12:36:11PM +0100, Peter Zijlstra wrote:
> static __always_inline void *__inline_memcpy(void *to, const void *from, size_t len)
> {
> void *ret = to;
>
> - asm volatile("rep movsb"
> - : "+D" (to), "+S" (from), "+c" (len)
> - : : "memory");
> - return ret;
> + asm volatile("1:\n\t"
> + ALT_64("rep movsb",
> + "call rep_movs_alternative", ALT_NOT(X86_FEATURE_FSRM))
I don't know if it matters, but this basically brings in a whole memcpy
to a text_poke situation, which should only be a handful of bytes, and
creates a new stack frame in the !FSRM case, which the __always_inline
was intending to avoid. But given what text_poke is, maybe micro
optimizations don't really matter. And fewer memcpy() implementations
seems like a good idea.
Thanks,
--
Alex
