@@ -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)
{
@@ -155,6 +155,8 @@ static int __cpuinit arch_timer_setup(struct clock_event_device *clk)
enable_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI], 0);
}
+ arch_counter_set_user_access();
+
return 0;
}
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 <mark.rutland@arm.com> --- arch/arm/include/asm/arch_timer.h | 12 ++++++++++++ arch/arm/kernel/arch_timer.c | 2 ++ 2 files changed, 14 insertions(+), 0 deletions(-)