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authorShanker Donthineni <shankerd@codeaurora.org>2017-12-11 16:42:32 -0600
committerWill Deacon <will.deacon@arm.com>2017-12-12 11:45:19 +0000
commit932b50c7c1c65e6f23002e075b97ee083c4a9e71 (patch)
treeb06e1770c79ff1418a96b48435b2bd6f8d226dc5 /Documentation
parentc622cc013cece073722592cff1ac6643a33b1622 (diff)
arm64: Add software workaround for Falkor erratum 1041
The ARM architecture defines the memory locations that are permitted to be accessed as the result of a speculative instruction fetch from an exception level for which all stages of translation are disabled. Specifically, the core is permitted to speculatively fetch from the 4KB region containing the current program counter 4K and next 4K. When translation is changed from enabled to disabled for the running exception level (SCTLR_ELn[M] changed from a value of 1 to 0), the Falkor core may errantly speculatively access memory locations outside of the 4KB region permitted by the architecture. The errant memory access may lead to one of the following unexpected behaviors. 1) A System Error Interrupt (SEI) being raised by the Falkor core due to the errant memory access attempting to access a region of memory that is protected by a slave-side memory protection unit. 2) Unpredictable device behavior due to a speculative read from device memory. This behavior may only occur if the instruction cache is disabled prior to or coincident with translation being changed from enabled to disabled. The conditions leading to this erratum will not occur when either of the following occur: 1) A higher exception level disables translation of a lower exception level (e.g. EL2 changing SCTLR_EL1[M] from a value of 1 to 0). 2) An exception level disabling its stage-1 translation if its stage-2 translation is enabled (e.g. EL1 changing SCTLR_EL1[M] from a value of 1 to 0 when HCR_EL2[VM] has a value of 1). To avoid the errant behavior, software must execute an ISB immediately prior to executing the MSR that will change SCTLR_ELn[M] from 1 to 0. Signed-off-by: Shanker Donthineni <shankerd@codeaurora.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/arm64/silicon-errata.txt1
1 files changed, 1 insertions, 0 deletions
diff --git a/Documentation/arm64/silicon-errata.txt b/Documentation/arm64/silicon-errata.txt
index 304bf22bb83c..fc1c884fea10 100644
--- a/Documentation/arm64/silicon-errata.txt
+++ b/Documentation/arm64/silicon-errata.txt
@@ -75,3 +75,4 @@ stable kernels.
| Qualcomm Tech. | Falkor v1 | E1003 | QCOM_FALKOR_ERRATUM_1003 |
| Qualcomm Tech. | Falkor v1 | E1009 | QCOM_FALKOR_ERRATUM_1009 |
| Qualcomm Tech. | QDF2400 ITS | E0065 | QCOM_QDF2400_ERRATUM_0065 |
+| Qualcomm Tech. | Falkor v{1,2} | E1041 | QCOM_FALKOR_ERRATUM_1041 |