Commit d1777e68 authored by Will Deacon's avatar Will Deacon
Browse files

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: default avatarMark Rutland <mark.rutland@arm.com>
Tested-by: default avatarLaura Abbott <labbott@redhat.com>
Tested-by: default avatarShanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 4bf3286d

arch/arm64/Kconfig

+5 −12
Original line number Diff line number Diff line
@@ -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"

arch/arm64/kernel/entry.S

+12 −0
Original line number Diff line number Diff line
@@ -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

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