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arm64: zero cntvoff_el2

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Currently cntvoff_el2 is initialised with an arbitrary bag of bits
derived from the initial value of cnthctl_el2 on the current CPU. This is
somewhat odd and problematic as some of these bits are UNKNOWN at reset
and may differ across CPUs (which may cause an OS at EL1 to observe time
going backwards across CPUs).

This patch instead initialises cntvoff_el2 with xzr, giving the register
a consistent value of zero on all CPUs.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Scott Wood <scottwood@freescale.com>
Cc: David Feng <fenghua@phytium.com.cn>
Cc: Tom Rini <trini@ti.com>
Acked-by: David.Feng <fenghua@phytium.com.cn>
This commit is contained in:
Mark Rutland 2014-05-21 14:29:23 +01:00 committed by Albert ARIBAUD
parent cb6d04d606
commit b924d586d7
1 changed files with 1 additions and 1 deletions
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2
arch/arm/cpu/armv8/transition.S
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@ -43,7 +43,7 @@ ENTRY(armv8_switch_to_el1)
mrs x0, cnthctl_el2
orr x0, x0, #0x3 /* Enable EL1 access to timers */
msr cnthctl_el2, x0
msr cntvoff_el2, x0
msr cntvoff_el2, xzr
mrs x0, cntkctl_el1
orr x0, x0, #0x3 /* Enable EL0 access to timers */
msr cntkctl_el1, x0