From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750936AbbFIMfX (ORCPT ); Tue, 9 Jun 2015 08:35:23 -0400 Received: from terminus.zytor.com ([198.137.202.10]:52012 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933392AbbFIMe5 (ORCPT ); Tue, 9 Jun 2015 08:34:57 -0400 Date: Tue, 9 Jun 2015 05:34:29 -0700 From: tip-bot for Dave Hansen Message-ID: Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, tglx@linutronix.de, dave.hansen@linux.intel.com, dave@sr71.net, torvalds@linux-foundation.org, akpm@linux-foundation.org, hpa@zytor.com, peterz@infradead.org Reply-To: hpa@zytor.com, peterz@infradead.org, linux-kernel@vger.kernel.org, mingo@kernel.org, dave.hansen@linux.intel.com, tglx@linutronix.de, dave@sr71.net, akpm@linux-foundation.org, torvalds@linux-foundation.org In-Reply-To: <20150607183704.3D69D5F4@viggo.jf.intel.com> References: <20150607183704.3D69D5F4@viggo.jf.intel.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/fpu] x86/mpx: Add temporary variable to reduce masking Git-Commit-ID: a1149fc83a1f97612e72ec24a0bdbabff7b85e77 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: a1149fc83a1f97612e72ec24a0bdbabff7b85e77 Gitweb: http://git.kernel.org/tip/a1149fc83a1f97612e72ec24a0bdbabff7b85e77 Author: Dave Hansen AuthorDate: Sun, 7 Jun 2015 11:37:04 -0700 Committer: Ingo Molnar CommitDate: Tue, 9 Jun 2015 12:24:33 +0200 x86/mpx: Add temporary variable to reduce masking When we allocate a bounds table, we call mmap(), then add a "valid" bit to the value before storing it in to the bounds directory. If we fail along the way, we go and mask that valid bit _back_ out. That seems a little silly, and this makes it much more clear when we have a plain address versus an actual table _entry_. Signed-off-by: Dave Hansen Reviewed-by: Thomas Gleixner Cc: Andrew Morton Cc: Dave Hansen Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/20150607183704.3D69D5F4@viggo.jf.intel.com Signed-off-by: Ingo Molnar --- arch/x86/mm/mpx.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c index c17fd27..4f7fb7c 100644 --- a/arch/x86/mm/mpx.c +++ b/arch/x86/mm/mpx.c @@ -429,6 +429,7 @@ static int allocate_bt(long __user *bd_entry) unsigned long expected_old_val = 0; unsigned long actual_old_val = 0; unsigned long bt_addr; + unsigned long bd_new_entry; int ret = 0; /* @@ -441,7 +442,7 @@ static int allocate_bt(long __user *bd_entry) /* * Set the valid flag (kinda like _PAGE_PRESENT in a pte) */ - bt_addr = bt_addr | MPX_BD_ENTRY_VALID_FLAG; + bd_new_entry = bt_addr | MPX_BD_ENTRY_VALID_FLAG; /* * Go poke the address of the new bounds table in to the @@ -455,7 +456,7 @@ static int allocate_bt(long __user *bd_entry) * of the MPX code that have to pagefault_disable(). */ ret = user_atomic_cmpxchg_inatomic(&actual_old_val, bd_entry, - expected_old_val, bt_addr); + expected_old_val, bd_new_entry); if (ret) goto out_unmap; @@ -486,7 +487,7 @@ static int allocate_bt(long __user *bd_entry) trace_mpx_new_bounds_table(bt_addr); return 0; out_unmap: - vm_munmap(bt_addr & MPX_BT_ADDR_MASK, MPX_BT_SIZE_BYTES); + vm_munmap(bt_addr, MPX_BT_SIZE_BYTES); return ret; }