From 2c32c65e3726c773760038910be30cce1b4d4149 Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Fri, 15 Aug 2014 12:11:50 +0100 Subject: ARM: 8129/1: errata: work around Cortex-A15 erratum 830321 using dummy strex 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 Cc: stable@vger.kernel.org Signed-off-by: Russell King --- arch/arm/include/asm/cacheflush.h | 1 - 1 file changed, 1 deletion(-) (limited to 'arch/arm/include/asm/cacheflush.h') diff --git a/arch/arm/include/asm/cacheflush.h b/arch/arm/include/asm/cacheflush.h index fd43f7f55b70..79ecb4f34ffb 100644 --- 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(volatile void *p, size_t size) "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" \ -- cgit v1.2.3