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Commit fcbdc5fe authored by Will Deacon's avatar Will Deacon Committed by Russell King
Browse files

ARM: 6772/1: errata: possible fault MMU translations following an ASID switch 



On the r2p* and r3p* versions of the Cortex-A9, a speculative memory
access may cause a page table walk which starts prior to an ASID switch
but completes afterwards. This can populate the micro-TLB with a stale
entry which may be hit with the new ASID.

This workaround places two dsb instructions in the mm switching code so
that no page table walks can cross the ASID switch.

Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent f5412be5

arch/arm/Kconfig

+11 −0
Original line number Diff line number Diff line
@@ -1202,6 +1202,17 @@ config ARM_ERRATA_753970 
	  This has the same effect as the cache sync operation: store buffer

	  drain and waiting for all buffers empty.



config ARM_ERRATA_754322

	bool "ARM errata: possible faulty MMU translations following an ASID switch"

	depends on CPU_V7

	help

	  This option enables the workaround for the 754322 Cortex-A9 (r2p*,

	  r3p*) erratum. A speculative memory access may cause a page table walk

	  which starts prior to an ASID switch but completes afterwards. This

	  can populate the micro-TLB with a stale entry which may be hit with

	  the new ASID. This workaround places two dsb instructions in the mm

	  switching code so that no page table walks can cross the ASID switch.



endmenu



source "arch/arm/common/Kconfig"

arch/arm/mm/proc-v7.S

+6 −0
Original line number Diff line number Diff line
@@ -107,11 +107,17 @@ ENTRY(cpu_v7_switch_mm) 
	ALT_UP(orr	r0, r0, #TTB_FLAGS_UP)

#ifdef CONFIG_ARM_ERRATA_430973

	mcr	p15, 0, r2, c7, c5, 6		@ flush BTAC/BTB

#endif

#ifdef CONFIG_ARM_ERRATA_754322

	dsb

#endif

	mcr	p15, 0, r2, c13, c0, 1		@ set reserved context ID

	isb

1:	mcr	p15, 0, r0, c2, c0, 0		@ set TTB 0

	isb

#ifdef CONFIG_ARM_ERRATA_754322

	dsb

#endif

	mcr	p15, 0, r1, c13, c0, 1		@ set context ID

	isb

#endif