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 <[email protected]>
Tested-by: Oleg Nesterov <[email protected]>
Reviewed-by: Frederic Weisbecker <[email protected]>
Originally-Reported-by: Vince Weaver <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Corey Ashford <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Vince Weaver <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index cb12fc9c0642052a8306a77f0425e03af2f2c08c..cf913587d4dd3674fe1f04ab8588e805fc7caa85 100644 (file)
--- 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));
 }