From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932278AbbCSBfE (ORCPT ); Wed, 18 Mar 2015 21:35:04 -0400 Received: from mail.kernel.org ([198.145.29.136]:52259 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751867AbbCSBdq (ORCPT ); Wed, 18 Mar 2015 21:33:46 -0400 From: Andy Lutomirski To: x86@kernel.org, linux-kernel@vger.kernel.org Cc: Brad Spengler , Denys Vlasenko , Andy Lutomirski Subject: [PATCH 6/9] x86: Make user_mode work correctly if regs came from vm86 mode Date: Wed, 18 Mar 2015 18:33:32 -0700 Message-Id: <0dd03eacb5f0a2b5ba0240de25347a31b493c289.1426728647.git.luto@kernel.org> 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 user_mode is now identical to user_mode_vm. Subsequent patches will change all callers of user_mode_vm to user_mode and then delete user_mode_vm. Signed-off-by: Andy Lutomirski --- arch/x86/include/asm/ptrace.h | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-) diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h index a60c59e977cc..6483525bb559 100644 --- a/arch/x86/include/asm/ptrace.h +++ b/arch/x86/include/asm/ptrace.h @@ -96,11 +96,13 @@ static inline unsigned long regs_return_value(struct pt_regs *regs) } /* - * user_mode_vm(regs) determines whether a register set came from user mode. - * This is true if V8086 mode was enabled OR if the register set was from - * protected mode with RPL-3 CS value. This tricky test checks that with - * one comparison. Many places in the kernel can bypass this full check - * if they have already ruled out V8086 mode, so user_mode(regs) can be used. + * user_mode(regs) determines whether a register set came from user + * mode. On x86_32, this is true if V8086 mode was enabled OR if the + * register set was from protected mode with RPL-3 CS value. This + * tricky test checks that with one comparison. + * + * On x86_64, vm86 mode is mercifully nonexistent, and we don't need + * the extra check. */ static inline int user_mode(struct pt_regs *regs) { @@ -113,12 +115,7 @@ static inline int user_mode(struct pt_regs *regs) static inline int user_mode_vm(struct pt_regs *regs) { -#ifdef CONFIG_X86_32 - return ((regs->cs & SEGMENT_RPL_MASK) | (regs->flags & X86_VM_MASK)) >= - USER_RPL; -#else return user_mode(regs); -#endif } /* -- 2.3.0