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Date:   Tue, 30 Apr 2019 11:38:57 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Ingo Molnar <mingo@kernel.org>
Cc:     Andy Lutomirski <luto@kernel.org>,
        Mike Rapoport <rppt@linux.ibm.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Alexandre Chartre <alexandre.chartre@oracle.com>,
        Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
        James Bottomley <James.Bottomley@hansenpartnership.com>,
        Jonathan Adams <jwadams@google.com>,
        Kees Cook <keescook@chromium.org>,
        Paul Turner <pjt@google.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Linux-MM <linux-mm@kvack.org>,
        LSM List <linux-security-module@vger.kernel.org>,
        X86 ML <x86@kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC PATCH 2/7] x86/sci: add core implementation for system call
 isolation
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On Tue, Apr 30, 2019 at 07:03:37AM +0200, Ingo Molnar wrote:
> So the question IMHO isn't whether it's "valid C", because we already 
> have the Linux kernel's own C syntax variant and are enforcing it with 
> varying degrees of success.

I'm not getting into the whole 'safe' fight here; but you're under
selling things. We don't have a C syntax, we have a full blown C
lanugeage variant.

The 'Kernel C' that we write is very much not 'ANSI/ISO C' anymore in a
fair number of places. And if I can get my way, we'll only diverge
further from the standard.

And this is quite separate from us using every GCC extention under the
sun; which of course also doesn't help. It mostly has to do with us
treating C as a portable assembler and the C people not wanting to
commit to sensible things because they think C is a high-level language.