Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755075Ab0KIUtA (ORCPT ); Tue, 9 Nov 2010 15:49:00 -0500 Received: from smtp.outflux.net ([198.145.64.163]:38498 "EHLO smtp.outflux.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755043Ab0KIUs6 (ORCPT ); Tue, 9 Nov 2010 15:48:58 -0500 Date: Tue, 9 Nov 2010 12:48:57 -0800 From: Kees Cook To: Pekka Enberg Cc: x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/4] x86: call verify_cpu during 32bit CPU startup Message-ID: <20101109204857.GT5876@outflux.net> References: <20101109181157.GE5876@outflux.net> <20101109181525.GH5876@outflux.net> <20101109191908.GO5876@outflux.net> <20101109195622.GR5876@outflux.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: Canonical X-HELO: www.outflux.net Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 954 Lines: 28 Hi Pekka, On Tue, Nov 09, 2010 at 10:28:16PM +0200, Pekka Enberg wrote: > So why can't we do patch 2/4 XD_DISABLE clearing in > early_init_intel()? Because it's too late, unfortunately. I went around a few times about this with Peter Anvin, and ultimately he agreed that it needed to go in verify_cpu() for now. > Why do we want to call verify_cpu() from > arch/x86/kernel/head_32.S and not from > arch/x86/boot/compressed/head_32.S like we do on 64-bit? Because the longmode/SSE tests being performed in verify_cpu() need to happen that early for 64bit. Instead of including it in two places for 32bit, we can just include it once in arch/x86/kernel/head_32.S. -Kees -- Kees Cook Ubuntu Security Team -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/