Re: [PATCH] [PATCH V2]ARM64: SCS: Add gcc plugin to support Shadow Call Stack

[Nick Desaulniers]

On Mon, Oct 11, 2021 at 8:42 AM Dan Li <ashimida@xxxxxxxxxxxxxxxxx> wrote:
>
>
>
> On 10/10/21 11:43 PM, Miguel Ojeda wrote:
> > On Sun, Oct 10, 2021 at 5:16 PM Dan Li <ashimida@xxxxxxxxxxxxxxxxx> wrote:
> >>
> >> -         This option enables Clang's Shadow Call Stack, which uses a
> >> -         shadow stack to protect function return addresses from being
> >> -         overwritten by an attacker. More information can be found in
> >> -         Clang's documentation:
> >> +         This option enables Clang/GCC plugin's Shadow Call Stack, which
> >> +         uses a shadow stack to protect function return addresses from
> >> +         being overwritten by an attacker. More information can be found
> >> +         in Clang's documentation:
> >
> > Perhaps it could be worded in a better way? It sounds like it is a
> > custom plugin for Clang as well, e.g.:
> >
> >      This option enables Shadow Call Stack (in the case of GCC, as a plugin),
> >
> > Cheers,
> > Miguel
> >
>
> Thanks Miguel.
>
> How about writing like this:
> This option enables Shadow Call Stack (supported as a compiler option in
> the case of clang, supported as a plugin in the case of gcc), which uses
> a shadow stack to ...

That sounds reasonable.

One question I have Dan, what is your sense for getting this feature
landed upstream in GCC proper?  It's neat to be able to use plugins to
support older versions of a compiler than when the feature initially
lands; I was curious if you're working to submit this into GCC as
well?  I didn't see anything in GCC's bug tracker for "shadow call
stack," but maybe there's a different feature bug tracking this?
-- 
Thanks,
~Nick Desaulniers