Re: [PATCH] x86/shstk: Enable shadow stack for x32

[H.J. Lu]

On Fri, Mar 22, 2024 at 7:07 AM Edgecombe, Rick P
<rick.p.edgecombe@xxxxxxxxx> wrote:
>
> On Fri, 2024-03-15 at 07:34 -0700, H.J. Lu wrote:
> > > How many people do you think will use this?
>
> I'm concerned that the only use of this will ever be exercise via the
> glibc unit tests, but will still require work to support.

 Correct.  A small glibc change is needed.  Will post it after
my kernel change is merged.


> > >
> > > I would have thought it would require more changes for basic x32
> >
> > This is all needed.
> >
> > > operation. What was the testing exactly?
> >
> > I configured x32 glibc with --enable-cet, build glibc and
> > run all glibc tests with shadow stack enabled.  There are
> > no regressions.  I verified that shadow stack is enabled
> > via /proc/pid/status.
>
> The shadow stack is supposed to be mapped above 4G, so how is this
> supposed to work for x32?

This is not what I see:

(gdb) info reg
..
pl3_ssp        0xf7dcbfe8          0xf7dcbfe8

--
H.J.