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authorWill Deacon <will.deacon@arm.com>2015-03-23 19:07:02 +0000
committerWill Deacon <will.deacon@arm.com>2015-04-01 10:24:31 +0100
commit905e8c5dcaa147163672b06fe9dcb5abaacbc711 (patch)
tree4284f6e2ecac493b6e4938e4b60e57fb521c3790 /arch/arm64/Kconfig
parentcc3979b54d5f1d5b5059b404892888c304d28080 (diff)
downloadop-kernel-dev-905e8c5dcaa147163672b06fe9dcb5abaacbc711.zip
op-kernel-dev-905e8c5dcaa147163672b06fe9dcb5abaacbc711.tar.gz
arm64: errata: add workaround for cortex-a53 erratum #845719
When running a compat (AArch32) userspace on Cortex-A53, a load at EL0 from a virtual address that matches the bottom 32 bits of the virtual address used by a recent load at (AArch64) EL1 might return incorrect data. This patch works around the issue by writing to the contextidr_el1 register on the exception return path when returning to a 32-bit task. This workaround is patched in at runtime based on the MIDR value of the processor. Reviewed-by: Marc Zyngier <marc.zyngier@arm.com> Tested-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/Kconfig')
-rw-r--r--arch/arm64/Kconfig21
1 files changed, 21 insertions, 0 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 02f67a9..23d51be 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -361,6 +361,27 @@ config ARM64_ERRATUM_832075
If unsure, say Y.
+config ARM64_ERRATUM_845719
+ bool "Cortex-A53: 845719: a load might read incorrect data"
+ depends on COMPAT
+ default y
+ help
+ This option adds an alternative code sequence to work around ARM
+ erratum 845719 on Cortex-A53 parts up to r0p4.
+
+ When running a compat (AArch32) userspace on an affected Cortex-A53
+ part, a load at EL0 from a virtual address that matches the bottom 32
+ bits of the virtual address used by a recent load at (AArch64) EL1
+ might return incorrect data.
+
+ The workaround is to write the contextidr_el1 register on exception
+ return to a 32-bit task.
+ Please note that this does not necessarily enable the workaround,
+ as it depends on the alternative framework, which will only patch
+ the kernel if an affected CPU is detected.
+
+ If unsure, say Y.
+
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