Hi Mark,
On Wed, 21 May 2014 14:29:23 +0100, Mark Rutland mark.rutland@arm.com wrote:
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
arch/arm/cpu/armv8/transition.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm/cpu/armv8/transition.S b/arch/arm/cpu/armv8/transition.S index e0a5946..38dea5c 100644 --- a/arch/arm/cpu/armv8/transition.S +++ b/arch/arm/cpu/armv8/transition.S @@ -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
Applied as a bug fix to u-boot-arm/master, thanks!
Amicalement,