Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933756AbaJDA2u (ORCPT ); Fri, 3 Oct 2014 20:28:50 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:45285 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755943AbaJCVm6 (ORCPT ); Fri, 3 Oct 2014 17:42:58 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mark Rutland , Will Deacon , Russell King Subject: [PATCH 3.16 178/357] ARM: 8129/1: errata: work around Cortex-A15 erratum 830321 using dummy strex Date: Fri, 3 Oct 2014 14:29:24 -0700 Message-Id: <20141003212938.823698574@linuxfoundation.org> X-Mailer: git-send-email 2.1.2 In-Reply-To: <20141003212933.458851516@linuxfoundation.org> References: <20141003212933.458851516@linuxfoundation.org> User-Agent: quilt/0.63-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mark Rutland commit 2c32c65e3726c773760038910be30cce1b4d4149 upstream. On revisions of Cortex-A15 prior to r3p3, a CLREX instruction at PL1 may falsely trigger a watchpoint exception, leading to potential data aborts during exception return and/or livelock. This patch resolves the issue in the following ways: - Replacing our uses of CLREX with a dummy STREX sequence instead (as we did for v6 CPUs). - Removing the clrex code from v7_exit_coherency_flush and derivatives, since this only exists as a minor performance improvement when non-cached exclusives are in use (Linux doesn't use these). Benchmarking on a variety of ARM cores revealed no measurable performance difference with this change applied, so the change is performed unconditionally and no new Kconfig entry is added. Signed-off-by: Mark Rutland Signed-off-by: Will Deacon Signed-off-by: Russell King Signed-off-by: Greg Kroah-Hartman --- arch/arm/include/asm/cacheflush.h | 1 - arch/arm/kernel/entry-header.S | 29 +++++++++++++++-------------- arch/arm/mach-exynos/mcpm-exynos.c | 1 - 3 files changed, 15 insertions(+), 16 deletions(-) --- a/arch/arm/include/asm/cacheflush.h +++ b/arch/arm/include/asm/cacheflush.h @@ -472,7 +472,6 @@ static inline void __sync_cache_range_r( "mcr p15, 0, r0, c1, c0, 0 @ set SCTLR \n\t" \ "isb \n\t" \ "bl v7_flush_dcache_"__stringify(level)" \n\t" \ - "clrex \n\t" \ "mrc p15, 0, r0, c1, c0, 1 @ get ACTLR \n\t" \ "bic r0, r0, #(1 << 6) @ disable local coherency \n\t" \ "mcr p15, 0, r0, c1, c0, 1 @ set ACTLR \n\t" \ --- a/arch/arm/kernel/entry-header.S +++ b/arch/arm/kernel/entry-header.S @@ -208,26 +208,21 @@ #endif .endif msr spsr_cxsf, \rpsr -#if defined(CONFIG_CPU_V6) - ldr r0, [sp] - strex r1, r2, [sp] @ clear the exclusive monitor - ldmib sp, {r1 - pc}^ @ load r1 - pc, cpsr -#elif defined(CONFIG_CPU_32v6K) - clrex @ clear the exclusive monitor - ldmia sp, {r0 - pc}^ @ load r0 - pc, cpsr -#else - ldmia sp, {r0 - pc}^ @ load r0 - pc, cpsr +#if defined(CONFIG_CPU_V6) || defined(CONFIG_CPU_32v6K) + @ We must avoid clrex due to Cortex-A15 erratum #830321 + sub r0, sp, #4 @ uninhabited address + strex r1, r2, [r0] @ clear the exclusive monitor #endif + ldmia sp, {r0 - pc}^ @ load r0 - pc, cpsr .endm .macro restore_user_regs, fast = 0, offset = 0 ldr r1, [sp, #\offset + S_PSR] @ get calling cpsr ldr lr, [sp, #\offset + S_PC]! @ get pc msr spsr_cxsf, r1 @ save in spsr_svc -#if defined(CONFIG_CPU_V6) +#if defined(CONFIG_CPU_V6) || defined(CONFIG_CPU_32v6K) + @ We must avoid clrex due to Cortex-A15 erratum #830321 strex r1, r2, [sp] @ clear the exclusive monitor -#elif defined(CONFIG_CPU_32v6K) - clrex @ clear the exclusive monitor #endif .if \fast ldmdb sp, {r1 - lr}^ @ get calling r1 - lr @@ -267,7 +262,10 @@ .endif ldr lr, [sp, #S_SP] @ top of the stack ldrd r0, r1, [sp, #S_LR] @ calling lr and pc - clrex @ clear the exclusive monitor + + @ We must avoid clrex due to Cortex-A15 erratum #830321 + strex r2, r1, [sp, #S_LR] @ clear the exclusive monitor + stmdb lr!, {r0, r1, \rpsr} @ calling lr and rfe context ldmia sp, {r0 - r12} mov sp, lr @@ -288,13 +286,16 @@ .endm #else /* ifdef CONFIG_CPU_V7M */ .macro restore_user_regs, fast = 0, offset = 0 - clrex @ clear the exclusive monitor mov r2, sp load_user_sp_lr r2, r3, \offset + S_SP @ calling sp, lr ldr r1, [sp, #\offset + S_PSR] @ get calling cpsr ldr lr, [sp, #\offset + S_PC] @ get pc add sp, sp, #\offset + S_SP msr spsr_cxsf, r1 @ save in spsr_svc + + @ We must avoid clrex due to Cortex-A15 erratum #830321 + strex r1, r2, [sp] @ clear the exclusive monitor + .if \fast ldmdb sp, {r1 - r12} @ get calling r1 - r12 .else --- a/arch/arm/mach-exynos/mcpm-exynos.c +++ b/arch/arm/mach-exynos/mcpm-exynos.c @@ -39,7 +39,6 @@ "mcr p15, 0, r0, c1, c0, 0 @ set SCTLR\n\t" \ "isb\n\t"\ "bl v7_flush_dcache_"__stringify(level)"\n\t" \ - "clrex\n\t"\ "mrc p15, 0, r0, c1, c0, 1 @ get ACTLR\n\t" \ "bic r0, r0, #(1 << 6) @ disable local coherency\n\t" \ /* Dummy Load of a device register to avoid Erratum 799270 */ \ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/