ARM: 8129/1: errata: work around Cortex-A15 erratum 830321 using dummy strex
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 <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
[lizf: Backported to 3.4:
- Drop changes to arch/arm/include/asm/cacheflush.h and
arch/arm/mach-exynos/mcpm-exynos.c]
Signed-off-by: Zefan Li <lizefan@huawei.com>
1 file changed