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/mach-exynos/mcpm-exynos.c | 1 - 1 file changed, 1 deletion(-) (limited to 'arch/arm/mach-exynos') diff --git a/arch/arm/mach-exynos/mcpm-exynos.c b/arch/arm/mach-exynos/mcpm-exynos.c index b2f8b60cf0e9..dc9a764a7c37 100644 --- a/arch/arm/mach-exynos/mcpm-exynos.c +++ b/arch/arm/mach-exynos/mcpm-exynos.c @@ -43,7 +43,6 @@ "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 */ \ -- cgit v1.2.3