Re: [PATCH v2 09/17] arm64: disable function graph tracing with SCS

Nick Desaulniers
2019-10-29T20:36:01Z

On Tue, Oct 29, 2019 at 10:45 AM Sami Tolvanen <samitolvanen@google.com> wrote:
>
> On Fri, Oct 25, 2019 at 4:03 AM Mark Rutland <mark.rutland@arm.com> wrote:
> > We have a similar issue with pointer authentication, and we're solving
> > that with -fpatchable-function-entry, which allows us to hook the
> > callsite before it does anything with the return address. IIUC we could
> > use the same mechanism here (and avoid introducing a third).
> >
> > Are there plans to implement -fpatchable-function-entry on the clang
> > side?
>
> I'm not sure if there are plans at the moment, but if this feature is
> needed for PAC, adding it to clang shouldn't be a problem. Nick, did
> you have any thoughts on this?

I didn't see anything explicitly in LLVM's issue tracker. I also
didn't see -fpatchable-function-entry currently in -next other than
under arch/parisc. Are there patches I can look at?

Has ARM's kernel team expressed the need to ARM's LLVM team?
--
Thanks,
~Nick Desaulniers