From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756025AbbHEWZz (ORCPT ); Wed, 5 Aug 2015 18:25:55 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:38310 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753937AbbHEVty (ORCPT ); Wed, 5 Aug 2015 17:49:54 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Andy Lutomirski , Ben Hutchings , Luis Henriques , Kamal Mostafa Subject: [PATCH 3.19.y-ckt 006/107] x86/nmi/64: Remove asm code that saves cr2 Date: Wed, 5 Aug 2015 14:47:58 -0700 Message-Id: <1438811379-384-7-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1438811379-384-1-git-send-email-kamal@canonical.com> References: <1438811379-384-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.19 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.19.8-ckt5 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Andy Lutomirski commit 0e181bb58143cb4a2e8f01c281b0816cd0e4798e upstream. Now that do_nmi saves cr2, we don't need to save it in asm. This is a prerequisity for the fix for CVE-2015-3290. Reviewed-by: Steven Rostedt Acked-by: Borislav Petkov Signed-off-by: Andy Lutomirski [bwh: Backported to 4.0: adjust filename, context] Signed-off-by: Ben Hutchings Acked-by: John Johansen Acked-by: Andy Whitcroft Signed-off-by: Luis Henriques Signed-off-by: Kamal Mostafa --- arch/x86/kernel/entry_64.S | 18 ------------------ 1 file changed, 18 deletions(-) diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 315f8e9..edffe680 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -1651,29 +1651,11 @@ end_repeat_nmi: call save_paranoid DEFAULT_FRAME 0 - /* - * Save off the CR2 register. If we take a page fault in the NMI then - * it could corrupt the CR2 value. If the NMI preempts a page fault - * handler before it was able to read the CR2 register, and then the - * NMI itself takes a page fault, the page fault that was preempted - * will read the information from the NMI page fault and not the - * origin fault. Save it off and restore it if it changes. - * Use the r12 callee-saved register. - */ - movq %cr2, %r12 - /* paranoidentry do_nmi, 0; without TRACE_IRQS_OFF */ movq %rsp,%rdi movq $-1,%rsi call do_nmi - /* Did the NMI take a page fault? Restore cr2 if it did */ - movq %cr2, %rcx - cmpq %rcx, %r12 - je 1f - movq %r12, %cr2 -1: - testl %ebx,%ebx /* swapgs needed? */ jnz nmi_restore nmi_swapgs: -- 1.9.1