Re: [PATCH] x86/alternatives: Fix alt_max_short macro to really be a max()

From: Michael Matz
Date: Thu Oct 05 2017 - 08:52:25 EST


On Thu, 5 Oct 2017, Borislav Petkov wrote:

> On Thu, Oct 05, 2017 at 02:35:33PM +0200, Mathias Krause wrote:
> > Note the "<"! ...comment is wrong, though the implementation works!
> I know, I realized that when I looked at alternative-asm.h. Wanted to
> double-check it with Micha first.

Yeah, for bit-twiddling the result of arithmetic would need to be
booleanized first, or alternatively the boolean operators be used in the
first place. So if '<' works then that's better in this context.

(In a different context, or in the same one there definitely was a problem
with using '<', but I can't remember the details, it's too long ago we
discussed about this; maybe it even was a problem only with some binutils
versions. So I'd suggest using the more obvious way until problems
reoccur, and then document why exactly using relational ops was a problem
;-) )