Commit ddd40da4 authored May 01, 2013 by Jiri Olsa Committed by Ingo Molnar May 28, 2013

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@redhat.com>
Tested-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com>
Originally-Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: Stephane Eranian <eranian@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1367421944-19082-4-git-send-email-jolsa@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 24cda109

arch/x86/kernel/signal.c

+3 −7

Original line number	Diff line number	Diff line
		@@ -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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