linux-kernel - [tip:perf/core] x86/signals: Merge EFLAGS bit clearing into a single statement

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Date:	Tue, 28 May 2013 05:54:07 -0700
From:	tip-bot for Jiri Olsa <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	eranian@...gle.com, mingo@...nel.org, a.p.zijlstra@...llo.nl,
	torvalds@...ux-foundation.org, acme@...stprotocols.net,
	jolsa@...hat.com, fweisbec@...il.com, akpm@...ux-foundation.org,
	tglx@...utronix.de, oleg@...hat.com, cjashfor@...ux.vnet.ibm.com,
	linux-kernel@...r.kernel.org, hpa@...or.com, paulus@...ba.org,
	andi@...stfloor.org, vincent.weaver@...ne.edu, mingo@...e.hu
Subject: [tip:perf/core] x86/signals:
  Merge EFLAGS bit clearing into a single statement

Commit-ID:  ddd40da4ccbabdd2e941837aa987e08dfa4396b4
Gitweb:     http://git.kernel.org/tip/ddd40da4ccbabdd2e941837aa987e08dfa4396b4
Author:     Jiri Olsa <jolsa@...hat.com>
AuthorDate: Wed, 1 May 2013 17:25:43 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 28 May 2013 08:46:53 +0200

x86/signals: Merge EFLAGS bit clearing into a single statement

Merging EFLAGS bit clearing into a single statement, to
ensure EFLAGS bits are being cleared in a single instruction.

Signed-off-by: Jiri Olsa <jolsa@...hat.com>
Tested-by: Oleg Nesterov <oleg@...hat.com>
Reviewed-by: Frederic Weisbecker <fweisbec@...il.com>
Originally-Reported-by: Vince Weaver <vincent.weaver@...ne.edu>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Andi Kleen <andi@...stfloor.org>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Arnaldo Carvalho de Melo <acme@...stprotocols.net>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Corey Ashford <cjashfor@...ux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Vince Weaver <vincent.weaver@...ne.edu>
Cc: Stephane Eranian <eranian@...gle.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Link: http://lkml.kernel.org/r/1367421944-19082-4-git-send-email-jolsa@redhat.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/signal.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index cb12fc9..cf91358 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -662,21 +662,17 @@ handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 	if (!failed) {
 		/*
 		 * Clear the direction flag as per the ABI for function entry.
-		 */
-		regs->flags &= ~X86_EFLAGS_DF;
-		/*
+		 *
 		 * Clear RF when entering the signal handler, because
 		 * it might disable possible debug exception from the
 		 * signal handler.
-		 */
-		regs->flags &= ~X86_EFLAGS_RF;
-		/*
+		 *
 		 * Clear TF when entering the signal handler, but
 		 * notify any tracer that was single-stepping it.
 		 * The tracer may want to single-step inside the
 		 * handler too.
 		 */
-		regs->flags &= ~X86_EFLAGS_TF;
+		regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF);
 	}
 	signal_setup_done(failed, ksig, test_thread_flag(TIF_SINGLESTEP));
 }
--
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