This is a note to let you know that I've just added the patch titled
arm64: Add software workaround for Falkor erratum 1041
to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm64-add-software-workaround-for-falkor-erratum-1041.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 932b50c7c1c65e6f23002e075b97ee083c4a9e71 Mon Sep 17 00:00:00 2001
From: Shanker Donthineni <shankerd@xxxxxxxxxxxxxx>
Date: Mon, 11 Dec 2017 16:42:32 -0600
Subject: arm64: Add software workaround for Falkor erratum 1041
From: Shanker Donthineni <shankerd@xxxxxxxxxxxxxx>
commit 932b50c7c1c65e6f23002e075b97ee083c4a9e71 upstream.
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@xxxxxxxxxxxxxx>
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Cc: Timur Tabi <timur@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
Documentation/arm64/silicon-errata.txt | 1 +
arch/arm64/Kconfig | 10 ++++++++++
arch/arm64/include/asm/assembler.h | 10 ++++++++++
arch/arm64/kernel/cpu-reset.S | 1 +
arch/arm64/kernel/efi-entry.S | 2 ++
arch/arm64/kernel/head.S | 1 +
arch/arm64/kernel/relocate_kernel.S | 1 +
arch/arm64/kvm/hyp-init.S | 1 +
8 files changed, 27 insertions(+)
--- a/Documentation/arm64/silicon-errata.txt
+++ b/Documentation/arm64/silicon-errata.txt
@@ -74,3 +74,4 @@ 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 |
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -539,6 +539,16 @@ config QCOM_QDF2400_ERRATUM_0065
If unsure, say Y.
+config QCOM_FALKOR_ERRATUM_E1041
+ bool "Falkor E1041: Speculative instruction fetches might cause errant memory access"
+ default y
+ help
+ Falkor CPU may speculatively fetch instructions from an improper
+ memory location when MMU translation is changed from SCTLR_ELn[M]=1
+ to SCTLR_ELn[M]=0. Prefix an ISB instruction to fix the problem.
+
+ If unsure, say Y.
+
endmenu
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -499,4 +499,14 @@ alternative_else_nop_endif
#endif
.endm
+/**
+ * Errata workaround prior to disable MMU. Insert an ISB immediately prior
+ * to executing the MSR that will change SCTLR_ELn[M] from a value of 1 to 0.
+ */
+ .macro pre_disable_mmu_workaround
+#ifdef CONFIG_QCOM_FALKOR_ERRATUM_E1041
+ isb
+#endif
+ .endm
+
#endif /* __ASM_ASSEMBLER_H */
--- a/arch/arm64/kernel/cpu-reset.S
+++ b/arch/arm64/kernel/cpu-reset.S
@@ -37,6 +37,7 @@ ENTRY(__cpu_soft_restart)
mrs x12, sctlr_el1
ldr x13, =SCTLR_ELx_FLAGS
bic x12, x12, x13
+ pre_disable_mmu_workaround
msr sctlr_el1, x12
isb
--- a/arch/arm64/kernel/efi-entry.S
+++ b/arch/arm64/kernel/efi-entry.S
@@ -96,6 +96,7 @@ ENTRY(entry)
mrs x0, sctlr_el2
bic x0, x0, #1 << 0 // clear SCTLR.M
bic x0, x0, #1 << 2 // clear SCTLR.C
+ pre_disable_mmu_workaround
msr sctlr_el2, x0
isb
b 2f
@@ -103,6 +104,7 @@ ENTRY(entry)
mrs x0, sctlr_el1
bic x0, x0, #1 << 0 // clear SCTLR.M
bic x0, x0, #1 << 2 // clear SCTLR.C
+ pre_disable_mmu_workaround
msr sctlr_el1, x0
isb
2:
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -732,6 +732,7 @@ __primary_switch:
* to take into account by discarding the current kernel mapping and
* creating a new one.
*/
+ pre_disable_mmu_workaround
msr sctlr_el1, x20 // disable the MMU
isb
bl __create_page_tables // recreate kernel mapping
--- a/arch/arm64/kernel/relocate_kernel.S
+++ b/arch/arm64/kernel/relocate_kernel.S
@@ -45,6 +45,7 @@ ENTRY(arm64_relocate_new_kernel)
mrs x0, sctlr_el2
ldr x1, =SCTLR_ELx_FLAGS
bic x0, x0, x1
+ pre_disable_mmu_workaround
msr sctlr_el2, x0
isb
1:
--- a/arch/arm64/kvm/hyp-init.S
+++ b/arch/arm64/kvm/hyp-init.S
@@ -151,6 +151,7 @@ reset:
mrs x5, sctlr_el2
ldr x6, =SCTLR_ELx_FLAGS
bic x5, x5, x6 // Clear SCTL_M and etc
+ pre_disable_mmu_workaround
msr sctlr_el2, x5
isb
Patches currently in stable-queue which might be from shankerd@xxxxxxxxxxxxxx are
queue-4.14/arm64-add-software-workaround-for-falkor-erratum-1041.patch
queue-4.14/arm64-define-cputype-macros-for-falkor-cpu.patch