From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756834AbdJPSyt (ORCPT ); Mon, 16 Oct 2017 14:54:49 -0400 Received: from terminus.zytor.com ([65.50.211.136]:46389 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756752AbdJPSyr (ORCPT ); Mon, 16 Oct 2017 14:54:47 -0400 Date: Mon, 16 Oct 2017 11:52:02 -0700 From: tip-bot for Thomas Gleixner Message-ID: Cc: luto@kernel.org, peterz@infradead.org, tglx@linutronix.de, mingo@kernel.org, linux-kernel@vger.kernel.org, whiteheadm@acm.org, hpa@zytor.com Reply-To: tglx@linutronix.de, luto@kernel.org, peterz@infradead.org, linux-kernel@vger.kernel.org, mingo@kernel.org, whiteheadm@acm.org, hpa@zytor.com In-Reply-To: References: To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/urgent] x86/idt: Initialize early IDT before cr4_init_shadow() Git-Commit-ID: 9c48c0965b97e14ddcf75490a754e84e05aaa062 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 9c48c0965b97e14ddcf75490a754e84e05aaa062 Gitweb: https://git.kernel.org/tip/9c48c0965b97e14ddcf75490a754e84e05aaa062 Author: Thomas Gleixner AuthorDate: Mon, 16 Oct 2017 12:12:16 +0200 Committer: Thomas Gleixner CommitDate: Mon, 16 Oct 2017 20:47:37 +0200 x86/idt: Initialize early IDT before cr4_init_shadow() Moving the early IDT setup out of assembly code breaks the boot on first generation 486 systems. The reason is that the call of idt_setup_early_handler, which sets up the early handlers was added after the call to cr4_init_shadow(). cr4_init_shadow() tries to read CR4 which is not available on those systems. The accessor function uses a extable fixup to handle the resulting fault. As the IDT is not set up yet, the cr4 read exception causes an instantaneous reboot for obvious reasons. Call idt_setup_early_handler() before cr4_init_shadow() so IDT is set up before the first exception hits. Fixes: 87e81786b13b ("x86/idt: Move early IDT setup out of 32-bit asm") Reported-and-tested-by: Matthew Whitehead Signed-off-by: Thomas Gleixner Cc: Peter Zijlstra Cc: Andy Lutomirski Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1710161210290.1973@nanos --- arch/x86/kernel/head32.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c index cf2ce06..2902ca4 100644 --- a/arch/x86/kernel/head32.c +++ b/arch/x86/kernel/head32.c @@ -30,10 +30,11 @@ static void __init i386_default_early_setup(void) asmlinkage __visible void __init i386_start_kernel(void) { - cr4_init_shadow(); - + /* Make sure IDT is set up before any exception happens */ idt_setup_early_handler(); + cr4_init_shadow(); + sanitize_boot_params(&boot_params); x86_early_init_platform_quirks();