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

[Eric Biggers]

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!

Eric