Re: [PATCH 06/18] add support for Clang's Shadow Call Stack (SCS)

Masahiro Yamada
2019-10-24T01:48:27Z

On Thu, Oct 24, 2019 at 1:59 AM Sami Tolvanen <samitolvanen@google.com> wrote:
>
> On Tue, Oct 22, 2019 at 9:28 AM Mark Rutland <mark.rutland@arm.com> wrote:
> > I think it would be preferable to follow the example of CC_FLAGS_FTRACE
> > so that this can be filtered out, e.g.
> >
> > ifdef CONFIG_SHADOW_CALL_STACK
> > CFLAGS_SCS := -fsanitize=shadow-call-stack
> > KBUILD_CFLAGS += $(CFLAGS_SCS)
> > export CC_FLAGS_SCS
> > endif
> >
> > ... with removal being:
> >
> > CFLAGS_REMOVE := $(CC_FLAGS_SCS)
> >
> > ... or:
> >
> > CFLAGS_REMOVE_obj.o := $(CC_FLAGS_SCS)
> >
> > That way you only need to define the flags once, so the enable and
> > disable falgs remain in sync by construction.
>
> CFLAGS_REMOVE appears to be only implemented for objects, which means
> there's no convenient way to filter out flags for everything in
> arch/arm64/kvm/hyp, for example. I could add a CFLAGS_REMOVE
> separately for each object file, or we could add something like
> ccflags-remove-y to complement ccflags-y, which should be relatively
> simple. Masahiro, do you have any suggestions?

I am fine with 'ccflags-remove-y'.

Thanks.

--
Best Regards
Masahiro Yamada