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arm64: Add work around for Arm Cortex-A55 Erratum 1024718

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Some variants of the Arm Cortex-55 cores (r0p0, r0p1, r1p0) suffer
from an erratum 1024718, which causes incorrect updates when DBM/AP
bits in a page table entry is modified without a break-before-make
sequence. The work around is to skip enabling the hardware DBM feature
on the affected cores. The hardware Access Flag management features
is not affected. There are some other cores suffering from this
errata, which could be added to the midr_list to trigger the work
around.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: ckadabi@codeaurora.org
Reviewed-by: Dave Martin <dave.martin@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Suzuki K Poulose 2018-03-26 15:12:49 +01:00 committed by Will Deacon
parent 05abb595bb
commit ece1397cbc
3 changed files with 30 additions and 1 deletions
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1
Documentation/arm64/silicon-errata.txt
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@ -55,6 +55,7 @@ stable kernels.
| ARM | Cortex-A57 | #834220 | ARM64_ERRATUM_834220 |
| ARM | Cortex-A72 | #853709 | N/A |
| ARM | Cortex-A73 | #858921 | ARM64_ERRATUM_858921 |
| ARM | Cortex-A55 | #1024718 | ARM64_ERRATUM_1024718 |
| ARM | MMU-500 | #841119,#826419 | N/A |
| | | | |
| Cavium | ThunderX ITS | #22375, #24313 | CAVIUM_ERRATUM_22375 |

14
arch/arm64/Kconfig
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@ -465,6 +465,20 @@ config ARM64_ERRATUM_843419
If unsure, say Y.
config ARM64_ERRATUM_1024718
bool "Cortex-A55: 1024718: Update of DBM/AP bits without break before make might result in incorrect update"
default y
help
This option adds work around for Arm Cortex-A55 Erratum 1024718.
Affected Cortex-A55 cores (r0p0, r0p1, r1p0) could cause incorrect
update of the hardware dirty bit when the DBM/AP bits are updated
without a break-before-make. The work around is to disable the usage
of hardware DBM locally on the affected cores. CPUs not affected by
erratum will continue to use the feature.
If unsure, say Y.
config CAVIUM_ERRATUM_22375
bool "Cavium erratum 22375, 24313"
default y

16
arch/arm64/kernel/cpufeature.c
View File

@ -966,9 +966,23 @@ static inline void __cpu_enable_hw_dbm(void)
isb();
}
static bool cpu_has_broken_dbm(void)
{
/* List of CPUs which have broken DBM support. */
static const struct midr_range cpus[] = {
#ifdef CONFIG_ARM64_ERRATUM_1024718
MIDR_RANGE(MIDR_CORTEX_A55, 0, 0, 1, 0), // A55 r0p0 -r1p0
#endif
{},
};
return is_midr_in_range_list(read_cpuid_id(), cpus);
}
static bool cpu_can_use_dbm(const struct arm64_cpu_capabilities *cap)
{
return has_cpuid_feature(cap, SCOPE_LOCAL_CPU);
return has_cpuid_feature(cap, SCOPE_LOCAL_CPU) &&
!cpu_has_broken_dbm();
}
static void cpu_enable_hw_dbm(struct arm64_cpu_capabilities const *cap)