From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755469AbbCSBfw (ORCPT ); Wed, 18 Mar 2015 21:35:52 -0400 Received: from mail.kernel.org ([198.145.29.136]:52228 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751564AbbCSBdn (ORCPT ); Wed, 18 Mar 2015 21:33:43 -0400 From: Andy Lutomirski To: x86@kernel.org, linux-kernel@vger.kernel.org Cc: Brad Spengler , Denys Vlasenko , Andy Lutomirski , Peter Zijlstra Subject: [PATCH 4/9] x86, perf: Explicitly optimize vm86 handling in code_segment_base Date: Wed, 18 Mar 2015 18:33:30 -0700 Message-Id: X-Mailer: git-send-email 2.3.0 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There's no point in checking the VM bit on 64-bit, and, since we're explicitly checking it, we can use user_mode_ignore_vm86 after the check. While we're at it, rearrange the ifdef slightly to make the code flow a bit clearer. Cc: Peter Zijlstra Signed-off-by: Andy Lutomirski --- arch/x86/kernel/cpu/perf_event.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 979963bb3977..56f7e60ad732 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -2147,18 +2147,19 @@ perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs) static unsigned long code_segment_base(struct pt_regs *regs) { /* + * For IA32 we look at the GDT/LDT segment base to convert the + * effective IP to a linear address. + */ + +#ifdef CONFIG_X86_32 + /* * If we are in VM86 mode, add the segment offset to convert to a * linear address. */ if (regs->flags & X86_VM_MASK) return 0x10 * regs->cs; - /* - * For IA32 we look at the GDT/LDT segment base to convert the - * effective IP to a linear address. - */ -#ifdef CONFIG_X86_32 - if (user_mode(regs) && regs->cs != __USER_CS) + if (user_mode_ignore_vm86(regs) && regs->cs != __USER_CS) return get_segment_base(regs->cs); #else if (user_mode(regs) && !user_64bit_mode(regs) && -- 2.3.0