Re: [PATCH] crypto: x86/aes - Don't use %rbp as temporary register

From: Eric Biggers
Date: Thu May 18 2017 - 22:50:30 EST

On Thu, May 18, 2017 at 08:56:32PM -0500, Josh Poimboeuf wrote:
> >
> > Hmm, it looks like a number of other algorithms in arch/x86/crypto/ use %rbp (or
> > %ebp), e.g. blowfish, camellia, cast5, and aes-i586. Presumably they have the
> > same problem. I'm a little confused: do these all need to be fixed, and
> > when/why did this start being considered broken?
> This warning was only recently added, with the goal of flushing out
> these types of issues with hand-coded asm to make frame pointer based
> stack traces more reliable. I can take a look at fixing the rest of
> them if you want.

Okay. I'm worried you might run into one that is difficult to fix due to lack
of spare registers. But if you're interested in looking into it, please go
ahead. Thanks!