[PATCH v4 1/5] gcc-plugins: arm-ssp: Prepare for THREAD_INFO_IN_TASK support

[Kees Cook]

On Wed, Sep 15, 2021 at 08:37:44AM +0200, Ard Biesheuvel wrote:
> On Wed, 15 Sept 2021 at 00:04, Linus Walleij <linus.walleij at linaro.org> wrote:
> >
> > Hi Ard,
> >
> > thanks for this patch series!
> >
> > On Mon, Sep 13, 2021 at 12:40 PM Ard Biesheuvel <ardb at kernel.org> wrote:
> >
> > >  config STACKPROTECTOR_PER_TASK
> > >         bool "Use a unique stack canary value for each task"
> > > -       depends on GCC_PLUGINS && STACKPROTECTOR && SMP && !XIP_DEFLATED_DATA
> > > +       depends on GCC_PLUGINS && STACKPROTECTOR && THREAD_INFO_IN_TASK && !XIP_DEFLATED_DATA
> > >         select GCC_PLUGIN_ARM_SSP_PER_TASK
> >
> > Am I reading this right that STACKPROTECTOR_PER_TASK
> > was available for ARMv6 with SMP before this
> > change and after this change it will only be available for
> > ARMv7 since THREAD_INFO_IN_TASK which is now a dependency
> > will only be available for ARMv7 (or ARMv6k)?
> >
> 
> Yes. We could potentially keep the old code path in the plugin as
> well, but what I would really prefer to do is get
> -mstack-protector-guard=tls implemented in GCC, so we can phase out
> the plugin entirely.

For tracking, I've added this for arm32 support:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102352

(And updated https://github.com/KSPP/linux/issues/29)

-- 
Kees Cook