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[2001:8b0:10b:1231::1]) by mx.google.com with ESMTPS id p20si26628804jam.1.2019.04.30.02.39.11 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 30 Apr 2019 02:39:11 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of peterz@infradead.org designates 2001:8b0:10b:1231::1 as permitted sender) client-ip=2001:8b0:10b:1231::1; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=merlin.20170209 header.b=QOy5xYDi; spf=pass (google.com: best guess record for domain of peterz@infradead.org designates 2001:8b0:10b:1231::1 as permitted sender) smtp.mailfrom=peterz@infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=R59xQNltNlo+UQspZjbwof7CktqW9+HwkEeV2CRgeuU=; b=QOy5xYDiWYSE3dg+lHcIEahnZ yso18XfZ2dJ+dYjUgeLSEj/9WsOa+WoKe+RQdMwsrNPXH3R6Xhq0TaOucgTPKijsid30226nZatGl pM3K0mFG5EGNvuvf/5r6+NLizmdw3kivj/5U+4ZRLWYOJgEP3ALrMYw5K99gEmJ7gNJo9VuqYPW7K +nik/sRvL/cofQIX6Qa6NnSG3Yk5PliBKEizrH5pibNe0KF0fxrUm9ipNL4VRP2k5HxSPYfaopNvG tZukHvNBTQgyf0/bTcSppTp6YdqDpsTc1X0cEt2RvMSGu1O4Q31Pj4PEoJRHsclvVgq/wI5oYG1A3 N5wdO5xFw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1hLPE4-0007rz-Ir; Tue, 30 Apr 2019 09:39:01 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 7510F29ACFA27; Tue, 30 Apr 2019 11:38:57 +0200 (CEST) Date: Tue, 30 Apr 2019 11:38:57 +0200 From: Peter Zijlstra To: Ingo Molnar Cc: Andy Lutomirski , Mike Rapoport , LKML , Alexandre Chartre , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Ingo Molnar , James Bottomley , Jonathan Adams , Kees Cook , Paul Turner , Thomas Gleixner , Linux-MM , LSM List , X86 ML , Linus Torvalds , Andrew Morton Subject: Re: [RFC PATCH 2/7] x86/sci: add core implementation for system call isolation Message-ID: <20190430093857.GO2623@hirez.programming.kicks-ass.net> References: <1556228754-12996-1-git-send-email-rppt@linux.ibm.com> <1556228754-12996-3-git-send-email-rppt@linux.ibm.com> <20190426083144.GA126896@gmail.com> <20190426095802.GA35515@gmail.com> <20190427084752.GA99668@gmail.com> <20190427104615.GA55518@gmail.com> <20190430050336.GA92357@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190430050336.GA92357@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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.