Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Tue, 19 Jul 2022 14:36:45 +0100
From:   Will Deacon <will@kernel.org>
To:     Kees Cook <keescook@chromium.org>
Cc:     Sami Tolvanen <samitolvanen@google.com>,
        linux-kernel@vger.kernel.org, Josh Poimboeuf <jpoimboe@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>, x86@kernel.org,
        Catalin Marinas <catalin.marinas@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Joao Moreira <joao@overdrivepizza.com>,
        Sedat Dilek <sedat.dilek@gmail.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        linux-hardening@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev
Subject: Re: [RFC PATCH v3 00/20] KCFI support
Message-ID: <20220719133645.GA14089@willie-the-truck>
References: <20220610233513.1798771-1-samitolvanen@google.com>
 <202206131001.6BA9933C@keescook>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <202206131001.6BA9933C@keescook>
User-Agent: Mutt/1.10.1 (2018-07-13)
Precedence: bulk

On Mon, Jun 13, 2022 at 10:04:12AM -0700, Kees Cook wrote:
> On Fri, Jun 10, 2022 at 04:34:53PM -0700, Sami Tolvanen wrote:
> > KCFI is a proposed forward-edge control-flow integrity scheme for
> > Clang, which is more suitable for kernel use than the existing CFI
> > scheme used by CONFIG_CFI_CLANG. KCFI doesn't require LTO, doesn't
> > alter function references to point to a jump table, and won't break
> > function address equality. The latest LLVM patch is here:
> > 
> >   https://reviews.llvm.org/D119296
> > 
> > This RFC series replaces the current arm64 CFI implementation with
> > KCFI and adds support for x86_64.
> 
> I think the "RFC" prefix for this series can be dropped. :)
> 
> It looks to me like all of Peter's concerns have been addressed. I'd say
> let's get the Clang side landed, and once that's done, land this via x86
> -tip?
> 
> Peter and Will does this sound right to you? It touches arm64, so if
> -tip isn't okay, I could take it in one of my trees?

The arm64 bits look fine to me. Please just check if it conflicts horribly
with -next so that we have a chance to figure out a shared branch if
necessary.

Will