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

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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>
This commit is contained in:
Jiri Olsa 2013-05-01 17:25:43 +02:00 committed by Ingo Molnar
parent 24cda10996
commit ddd40da4cc
1 changed files with 3 additions and 7 deletions
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10
arch/x86/kernel/signal.c
View file

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