Re: [RFC/RFT] CFI: Add support for gcc CFI in aarch64

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>,
	Andrew Morton <akpm@linux-foundation.org>,
	Uros Bizjak <ubizjak@gmail.com>,
	Kumar Kartikeya Dwivedi <memxor@gmail.com>,
	Juergen Gross <jgross@suse.com>,
	Luis Chamberlain <mcgrof@kernel.org>,
	Borislav Petkov <bp@suse.de>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Dmitry Torokhov <dmitry.torokhov@gmail.com>,
	Aaron Tomlin <atomlin@redhat.com>,
	Kalesh Singh <kaleshsingh@google.com>,
	Yuntao Wang <ytcoode@gmail.com>,
	Changbin Du <changbin.du@intel.com>,
	linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev
Subject: Re: [RFC/RFT] CFI: Add support for gcc CFI in aarch64
Date: Mon, 19 Dec 2022 05:32:04 -0800	[thread overview]
Message-ID: <20221219132731.6ng4sz2nv6ujvu7i@ubuntu> (raw)
In-Reply-To: <Y6A/k7/KrCCDuux6@hirez.programming.kicks-ass.net>

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

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