Re: [PATCH v4 07/10] x86: narrow out of bounds syscalls to sys_read under speculation

[Linus Torvalds]

On Tue, Feb 6, 2018 at 12:49 PM, Andy Lutomirski <luto@xxxxxxxxxx> wrote:
>
> Can you use @cc to make an asm statement that outputs both the masked
> array index and the "if" condition?  I can never remember the syntax,
> but something like:

Yes. Although I'd actually suggest just using an "asm goto" if we
really want to optimize this. Give the "index_mask_nospec()" a third
argument that is the label to jump to for overflow.

Then you can just decide how to implement it best for any particular
architecture (and compiler limitation).

              Linus