From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751428Ab2CEVGd (ORCPT ); Mon, 5 Mar 2012 16:06:33 -0500 Received: from a.ns.miles-group.at ([95.130.255.143]:47834 "EHLO radon.swed.at" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750868Ab2CEVGc (ORCPT ); Mon, 5 Mar 2012 16:06:32 -0500 From: Richard Weinberger To: jonas@southpole.se Cc: linux@openrisc.net, linux-kernel@vger.kernel.org, Richard Weinberger Subject: [PATCH] OpenRISC: Handle r0 with care Date: Mon, 5 Mar 2012 22:07:07 +0100 Message-Id: <1330981627-16121-1-git-send-email-richard@nod.at> X-Mailer: git-send-email 1.7.6 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Depending on the OpenRISC implementation a rough task may able to change r0 and corrupt other taks. Handle this case by setting r0 to zero on each entry point. Also ensure that r0 is really zero before jumping into _start. Signed-off-by: Richard Weinberger diff --git a/arch/openrisc/kernel/entry.S b/arch/openrisc/kernel/entry.S index d5f9c35..7c9c4f6 100644 --- a/arch/openrisc/kernel/entry.S +++ b/arch/openrisc/kernel/entry.S @@ -130,6 +130,7 @@ handler: ;\ #define UNHANDLED_EXCEPTION(handler,vector) \ .global handler ;\ handler: ;\ + l.andi r0,r0,0 ;\ /* r1, EPCR, ESR already saved */ ;\ l.sw PT_GPR2(r1),r2 ;\ l.sw PT_GPR3(r1),r3 ;\ @@ -185,8 +186,8 @@ handler: ;\ /* ---[ 0x100: RESET exception ]----------------------------------------- */ EXCEPTION_ENTRY(_tng_kernel_start) + l.andi r0,r0,0 l.jal _start - l.andi r0,r0,0 /* ---[ 0x200: BUS exception ]------------------------------------------- */ @@ -976,6 +977,7 @@ ENTRY(_kernel_thread_helper) .align 0x400 ENTRY(_switch) + l.andi r0,r0,0 /* We don't store SR as _switch only gets called in a context where * the SR will be the same going in and coming out... */ diff --git a/arch/openrisc/kernel/head.S b/arch/openrisc/kernel/head.S index c75018d..c439324 100644 --- a/arch/openrisc/kernel/head.S +++ b/arch/openrisc/kernel/head.S @@ -152,6 +152,7 @@ */ #define EXCEPTION_HANDLE(handler) \ + l.andi r0,r0,0 ;\ EXCEPTION_T_STORE_GPR30 ;\ l.mfspr r30,r0,SPR_ESR_BASE ;\ l.andi r30,r30,SPR_SR_SM ;\ -- 1.7.6