linux-kernel - [PATCH RFC][try 2] IA64 signal : remove redundant code in setup

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Date:	Thu, 22 Nov 2007 11:15:55 +0800
From:	Shi Weihua <shiwh@...fujitsu.com>
To:	linux-kernel@...r.kernel.org
CC:	tony.luck@...el.com, linux-ia64@...r.kernel.org
Subject: [PATCH RFC][try 2] IA64 signal : remove redundant code in setup_sigcontext()

This patch removes some redundant code in the function setup_sigcontext().

The registers ar.ccv,b7,r14,ar.csd,ar.ssd,r2-r3 and r16-r31 are not restored 
in restore_sigcontext() when (flags & IA64_SC_FLAG_IN_SYSCALL) is true. 
So we don't need to zero those variables in setup_sigcontext().

Signed-off-by: Shi Weihua <shiwh@...fujitsu.com> 

---
diff -urp linux-2.6.24-rc3-git1.orig/arch/ia64/kernel/signal.c linux-2.6.24-rc3-git1/arch/ia64/kernel/signal.c
--- linux-2.6.24-rc3-git1.orig/arch/ia64/kernel/signal.c	2007-11-17 13:16:36.000000000 +0800
+++ linux-2.6.24-rc3-git1/arch/ia64/kernel/signal.c	2007-11-22 11:02:27.000000000 +0800
@@ -280,15 +280,7 @@ setup_sigcontext (struct sigcontext __us
 	err |= __copy_to_user(&sc->sc_gr[15], &scr->pt.r15, 8);		/* r15 */
 	err |= __put_user(scr->pt.cr_iip + ia64_psr(&scr->pt)->ri, &sc->sc_ip);
 
-	if (flags & IA64_SC_FLAG_IN_SYSCALL) {
-		/* Clear scratch registers if the signal interrupted a system call. */
-		err |= __put_user(0, &sc->sc_ar_ccv);				/* ar.ccv */
-		err |= __put_user(0, &sc->sc_br[7]);				/* b7 */
-		err |= __put_user(0, &sc->sc_gr[14]);				/* r14 */
-		err |= __clear_user(&sc->sc_ar25, 2*8);			/* ar.csd & ar.ssd */
-		err |= __clear_user(&sc->sc_gr[2], 2*8);			/* r2-r3 */
-		err |= __clear_user(&sc->sc_gr[16], 16*8);			/* r16-r31 */
-	} else {
+	if (!(flags & IA64_SC_FLAG_IN_SYSCALL)) {
 		/* Copy scratch regs to sigcontext if the signal didn't interrupt a syscall. */
 		err |= __put_user(scr->pt.ar_ccv, &sc->sc_ar_ccv);		/* ar.ccv */
 		err |= __put_user(scr->pt.b7, &sc->sc_br[7]);			/* b7 */

-
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