From b2deabe3ba664a1ec47400c0ca285e951874e0cc Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Wed, 14 Nov 2012 10:32:24 +0000 Subject: arm: arch_timer: add arch_counter_set_user_access Several bits in CNTKCTL reset to 0, including PL0VTEN. For architectures using the generic timer which wish to have a fast gettimeofday vDSO implementation, these bits must be set to 1 by the kernel. For architectures without a vDSO, it's best to leave the bits set to 0 for now to ensure that if and when support is added, it's implemented sanely architecture wide. As the bootloader might set PL0VTEN to a value that doesn't correspond to that which the kernel prefers, we must explicitly set it to the architecture port's preferred value. This patch adds arch_counter_set_user_access, which sets the PL0 access permissions to that required by the architecture. For arch/arm, this currently means disabling all userspace access. Signed-off-by: Mark Rutland Acked-by: Catalin Marinas --- arch/arm/include/asm/arch_timer.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'arch/arm/include') diff --git a/arch/arm/include/asm/arch_timer.h b/arch/arm/include/asm/arch_timer.h index 75975d9efd3f..729f6d98df86 100644 --- a/arch/arm/include/asm/arch_timer.h +++ b/arch/arm/include/asm/arch_timer.h @@ -106,6 +106,18 @@ static inline u64 arch_counter_get_cntvct(void) asm volatile("mrrc p15, 1, %Q0, %R0, c14" : "=r" (cval)); return cval; } + +static inline void __cpuinit arch_counter_set_user_access(void) +{ + u32 cntkctl; + + asm volatile("mrc p15, 0, %0, c14, c1, 0" : "=r" (cntkctl)); + + /* disable user access to everything */ + cntkctl &= ~((3 << 8) | (7 << 0)); + + asm volatile("mcr p15, 0, %0, c14, c1, 0" : : "r" (cntkctl)); +} #else static inline int arch_timer_of_register(void) { -- cgit v1.2.2