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authorWill Deacon <will.deacon@arm.com>2017-11-14 14:29:19 +0000
committerWill Deacon <will.deacon@arm.com>2017-12-11 13:41:00 +0000
commitd1777e686ad10ba7c594304429c6045fb79255a1 (patch)
tree623e085fa5446b993d2dca09e86d37fa89102964
parent4bf3286d29f3a88425d8d8cd53428cbb8f865f04 (diff)
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arm64: erratum: Work around Falkor erratum #E1003 in trampoline code
We rely on an atomic swizzling of TTBR1 when transitioning from the entry trampoline to the kernel proper on an exception. We can't rely on this atomicity in the face of Falkor erratum #E1003, so on affected cores we can issue a TLB invalidation to invalidate the walk cache prior to jumping into the kernel. There is still the possibility of a TLB conflict here due to conflicting walk cache entries prior to the invalidation, but this doesn't appear to be the case on these CPUs in practice. Reviewed-by: Mark Rutland <mark.rutland@arm.com> Tested-by: Laura Abbott <labbott@redhat.com> Tested-by: Shanker Donthineni <shankerd@codeaurora.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
-rw-r--r--arch/arm64/Kconfig17
-rw-r--r--arch/arm64/kernel/entry.S12
2 files changed, 17 insertions, 12 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index a93339f5178f..fdcc7b9bb15d 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -522,20 +522,13 @@ config CAVIUM_ERRATUM_30115
config QCOM_FALKOR_ERRATUM_1003
bool "Falkor E1003: Incorrect translation due to ASID change"
default y
- select ARM64_PAN if ARM64_SW_TTBR0_PAN
help
On Falkor v1, an incorrect ASID may be cached in the TLB when ASID
- and BADDR are changed together in TTBRx_EL1. The workaround for this
- issue is to use a reserved ASID in cpu_do_switch_mm() before
- switching to the new ASID. Saying Y here selects ARM64_PAN if
- ARM64_SW_TTBR0_PAN is selected. This is done because implementing and
- maintaining the E1003 workaround in the software PAN emulation code
- would be an unnecessary complication. The affected Falkor v1 CPU
- implements ARMv8.1 hardware PAN support and using hardware PAN
- support versus software PAN emulation is mutually exclusive at
- runtime.
-
- If unsure, say Y.
+ and BADDR are changed together in TTBRx_EL1. Since we keep the ASID
+ in TTBR1_EL1, this situation only occurs in the entry trampoline and
+ then only for entries in the walk cache, since the leaf translation
+ is unchanged. Work around the erratum by invalidating the walk cache
+ entries for the trampoline before entering the kernel proper.
config QCOM_FALKOR_ERRATUM_1009
bool "Falkor E1009: Prematurely complete a DSB after a TLBI"
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 39e3873b8d5a..ce56592b5f70 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -989,6 +989,18 @@ __ni_sys_trace:
sub \tmp, \tmp, #(SWAPPER_DIR_SIZE + RESERVED_TTBR0_SIZE)
bic \tmp, \tmp, #USER_ASID_FLAG
msr ttbr1_el1, \tmp
+#ifdef CONFIG_QCOM_FALKOR_ERRATUM_1003
+alternative_if ARM64_WORKAROUND_QCOM_FALKOR_E1003
+ /* ASID already in \tmp[63:48] */
+ movk \tmp, #:abs_g2_nc:(TRAMP_VALIAS >> 12)
+ movk \tmp, #:abs_g1_nc:(TRAMP_VALIAS >> 12)
+ /* 2MB boundary containing the vectors, so we nobble the walk cache */
+ movk \tmp, #:abs_g0_nc:((TRAMP_VALIAS & ~(SZ_2M - 1)) >> 12)
+ isb
+ tlbi vae1, \tmp
+ dsb nsh
+alternative_else_nop_endif
+#endif /* CONFIG_QCOM_FALKOR_ERRATUM_1003 */
.endm
.macro tramp_unmap_kernel, tmp