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Date:   Mon, 19 Dec 2022 05:32:04 -0800
From:   Dan Li <ashimida.1990@gmail.com>
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Masahiro Yamada <masahiroy@kernel.org>,
        Michal Marek <michal.lkml@markovi.net>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Sami Tolvanen <samitolvanen@google.com>,
        Kees Cook <keescook@chromium.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Tom Rix <trix@redhat.com>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Josh Poimboeuf <jpoimboe@kernel.org>,
        Frederic Weisbecker <frederic@kernel.org>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Marco Elver <elver@google.com>,
        Christophe Leroy <christophe.leroy@csgroup.eu>,
        Song Liu <song@kernel.org>,
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        linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev
Subject: Re: [RFC/RFT] CFI: Add support for gcc CFI in aarch64
Message-ID: <20221219132731.6ng4sz2nv6ujvu7i@ubuntu>
References: <20221219061758.23321-1-ashimida.1990@gmail.com>
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Hi Peter,

On 12/19, Peter Zijlstra wrote:
> On Sun, Dec 18, 2022 at 10:17:58PM -0800, Dan Li wrote:
> 
> > 1. When a typeid mismatch is detected, the cfi_check_failed function
> >    will be called instead of the brk instruction. This function needs
> >    to be implemented by the compiler user.
> >    If there are user mode programs or other systems that want to use
> >    this feature, it may be more convenient to use a callback (so this
> >    compilation option is set to -fsanitize=cfi instead of kcfi).
> 
> This is not going to be acceptible for x86_64.

I'm not familiar enough with the x86_64 platform, could you please
tell me why this is not acceptable? Is there a similar situation
on the arm64 platform?

> > 5. The current implementation of gcc only supports the aarch64 platform.
> 
> What, if any, are the plans for x86_64 support?

I'd like to implement something similar on x86_64 later, but
currently I'm doing this in my spare time, so it might take a
little longer. :(

Thanks,
Dan