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From:   Sami Tolvanen <samitolvanen@google.com>
Date:   Mon, 27 Mar 2023 15:17:43 -0700
Message-ID: <CABCJKueH6ohH27xCPz9a_ndRR26Na_mo=MGF3eqjwV2=gJy+wQ@mail.gmail.com>
Subject: Re: [RFC/RFT,V2] CFI: Add support for gcc CFI in aarch64
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Dan Li <ashimida.1990@gmail.com>,
        Aaron Tomlin <atomlin@redhat.com>,
        Alexander Potapenko <glider@google.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
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On Mon, Mar 27, 2023 at 2:30=E2=80=AFAM Peter Zijlstra <peterz@infradead.or=
g> wrote:
>
> On Sat, Mar 25, 2023 at 01:54:16AM -0700, Dan Li wrote:
>
> > In the compiler part[4], most of the content is the same as Sami's
> > implementation[3], except for some minor differences, mainly including:
> >
> > 1. The function typeid is calculated differently and it is difficult
> > to be consistent.
>
> This means there is an effective ABI break between the compilers, which
> is sad :-( Is there really nothing to be done about this?

I agree, this would be unfortunate, and would also be a compatibility
issue with rustc where there's ongoing work to support
clang-compatible CFI type hashes:

https://github.com/rust-lang/rust/pull/105452

Sami