commit 8b9c5ff380aa4f10658171ed2b9abc1e0861b770
author Roland McGrath <roland@redhat.com> Sat Apr 19 14:26:54 2008 -0700
committer Ingo Molnar <mingo@elte.hu> Sat Apr 26 17:35:47 2008 +0200
tree 25cc707163471e593274a16fe3623801b6f0a7a6
parent f7f17a67c589f031c567d9fdc809dee7c5868c8a

x86 signals: lift flags diddling code

This lifts the code diddling the TF and DF bits for signal handler setup
out of the several places copying the same code into the one place that
calls them all.  There is no change in what it does.

I also separated the recently-added DF bit clearing from the TF diddling.
The compiler turns them back into one instruction anyway.  The tossing
in of DF to the same line of code with no new comments was a bit more
arcane than seems wise.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/signal_32.c

diff --git a/arch/x86/kernel/signal_32.c b/arch/x86/kernel/signal_32.c
index f1b1179..8e05e7f 100644
--- a/arch/x86/kernel/signal_32.c
+++ b/arch/x86/kernel/signal_32.c
@@ -413,16 +413,6 @@
 	regs->ss = __USER_DS;
 	regs->cs = __USER_CS;
 
-	/*
-	 * 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 | X86_EFLAGS_DF);
-	if (test_thread_flag(TIF_SINGLESTEP))
-		ptrace_notify(SIGTRAP);
-
 	return 0;
 
 give_sigsegv:
@@ -501,16 +491,6 @@
 	regs->ss = __USER_DS;
 	regs->cs = __USER_CS;
 
-	/*
-	 * 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 | X86_EFLAGS_DF);
-	if (test_thread_flag(TIF_SINGLESTEP))
-		ptrace_notify(SIGTRAP);
-
 	return 0;
 
 give_sigsegv:
@@ -566,6 +546,21 @@
 	if (ret)
 		return ret;
 
+	/*
+	 * Clear the direction flag as per the ABI for function entry.
+	 */
+	regs->flags &= ~X86_EFLAGS_DF;
+
+	/*
+	 * 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;
+	if (test_thread_flag(TIF_SINGLESTEP))
+		ptrace_notify(SIGTRAP);
+
 	spin_lock_irq(&current->sighand->siglock);
 	sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
 	if (!(ka->sa.sa_flags & SA_NODEFER))