From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762324AbbA1FQD (ORCPT ); Wed, 28 Jan 2015 00:16:03 -0500 Received: from mail.kernel.org ([198.145.29.136]:37974 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933828AbbA1ERF (ORCPT ); Tue, 27 Jan 2015 23:17:05 -0500 From: lizf@kernel.org To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Geert Uytterhoeven , Zefan Li Subject: [PATCH 3.4 039/177] m68k: Disable/restore interrupts in hwreg_present()/hwreg_write() Date: Wed, 28 Jan 2015 12:07:25 +0800 Message-Id: <1422418236-12852-78-git-send-email-lizf@kernel.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1422418050-12581-1-git-send-email-lizf@kernel.org> References: <1422418050-12581-1-git-send-email-lizf@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Geert Uytterhoeven 3.4.106-rc1 review patch. If anyone has any objections, please let me know. ------------------ commit e4dc601bf99ccd1c95b7e6eef1d3cf3c4b0d4961 upstream. hwreg_present() and hwreg_write() temporarily change the VBR register to another vector table. This table contains a valid bus error handler only, all other entries point to arbitrary addresses. If an interrupt comes in while the temporary table is active, the processor will start executing at such an arbitrary address, and the kernel will crash. While most callers run early, before interrupts are enabled, or explicitly disable interrupts, Finn Thain pointed out that macsonic has one callsite that doesn't, causing intermittent boot crashes. There's another unsafe callsite in hilkbd. Fix this for good by disabling and restoring interrupts inside hwreg_present() and hwreg_write(). Explicitly disabling interrupts can be removed from the callsites later. Reported-by: Finn Thain Signed-off-by: Geert Uytterhoeven Signed-off-by: Zefan Li --- arch/m68k/mm/hwtest.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/m68k/mm/hwtest.c b/arch/m68k/mm/hwtest.c index 2c7dde3..2a5259f 100644 --- a/arch/m68k/mm/hwtest.c +++ b/arch/m68k/mm/hwtest.c @@ -28,9 +28,11 @@ int hwreg_present( volatile void *regp ) { int ret = 0; + unsigned long flags; long save_sp, save_vbr; long tmp_vectors[3]; + local_irq_save(flags); __asm__ __volatile__ ( "movec %/vbr,%2\n\t" "movel #Lberr1,%4@(8)\n\t" @@ -46,6 +48,7 @@ int hwreg_present( volatile void *regp ) : "=&d" (ret), "=&r" (save_sp), "=&r" (save_vbr) : "a" (regp), "a" (tmp_vectors) ); + local_irq_restore(flags); return( ret ); } @@ -58,9 +61,11 @@ EXPORT_SYMBOL(hwreg_present); int hwreg_write( volatile void *regp, unsigned short val ) { int ret; + unsigned long flags; long save_sp, save_vbr; long tmp_vectors[3]; + local_irq_save(flags); __asm__ __volatile__ ( "movec %/vbr,%2\n\t" "movel #Lberr2,%4@(8)\n\t" @@ -78,6 +83,7 @@ int hwreg_write( volatile void *regp, unsigned short val ) : "=&d" (ret), "=&r" (save_sp), "=&r" (save_vbr) : "a" (regp), "a" (tmp_vectors), "g" (val) ); + local_irq_restore(flags); return( ret ); } -- 1.9.1