From mboxrd@z Thu Jan 1 00:00:00 1970 From: dave.martin@linaro.org (Dave Martin) Date: Wed, 30 Nov 2011 11:12:04 +0000 Subject: [PATCH v2] ARM: errata: Remove SMP dependency for erratum 751472 Message-ID: <1322651524-24095-1-git-send-email-dave.martin@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Activation conditions for a workaround should not be encoded in the workaround's direct dependencies if this makes otherwise reasonable configuration choices impossible. This patches uses the SMP/UP patching facilities instead to compile out the workaround if the configuration means that it is definitely not needed. This means that configs for buggy silicon can simply select ARM_ERRATA_751472, without preventing a UP kernel from being built or duplicatiing knowledge about when to activate the workaround. This seems the correct why to do things, because the erratum is a property of the silicon, irrespective of what the kernel config happens to be. Signed-off-by: Dave Martin --- Changes since v1: v2: Fix incorrect use of ALT_SMP()/ALT_UP_B(): they must be used in the correct order, otherwise the fixup will reference the wrong ALT_SMP() block and get applied in the wrong place. Make the whole erratum workaround #ifdef CONFIG_SMP so that we don't leave some dead code and an unnecessary branch in the image when building a uniprocessor kernel. arch/arm/Kconfig | 2 +- arch/arm/mm/proc-v7.S | 6 ++++-- 2 files changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 44789ef..e5bbb2f 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -1281,7 +1281,7 @@ config ARM_ERRATA_743622 config ARM_ERRATA_751472 bool "ARM errata: Interrupted ICIALLUIS may prevent completion of broadcasted operation" - depends on CPU_V7 && SMP + depends on CPU_V7 help This option enables the workaround for the 751472 Cortex-A9 (prior to r3p0) erratum. An interrupted ICIALLUIS operation may prevent the diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S index 2c559ac..e70a737 100644 --- a/arch/arm/mm/proc-v7.S +++ b/arch/arm/mm/proc-v7.S @@ -363,11 +363,13 @@ __v7_setup: orreq r10, r10, #1 << 6 @ set bit #6 mcreq p15, 0, r10, c15, c0, 1 @ write diagnostic register #endif -#ifdef CONFIG_ARM_ERRATA_751472 - cmp r6, #0x30 @ present prior to r3p0 +#if defined(CONFIG_ARM_ERRATA_751472) && defined(CONFIG_SMP) + ALT_SMP(cmp r6, #0x30) @ present prior to r3p0 + ALT_UP_B(1f) mrclt p15, 0, r10, c15, c0, 1 @ read diagnostic register orrlt r10, r10, #1 << 11 @ set bit #11 mcrlt p15, 0, r10, c15, c0, 1 @ write diagnostic register +1: #endif 3: mov r10, #0 -- 1.7.4.1