| Message ID | 1359634539-9580-10-git-send-email-mark.rutland@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Jan 31, 2013 at 12:15:32PM +0000, Mark Rutland wrote: > 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> Acked-by: Catalin Marinas <catalin.marinas@arm.com>
diff --git a/arch/arm/include/asm/arch_timer.h b/arch/arm/include/asm/arch_timer.h index 75975d9..729f6d9 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) { diff --git a/arch/arm/kernel/arch_timer.c b/arch/arm/kernel/arch_timer.c index c8dfec0..94f5033 100644 --- a/arch/arm/kernel/arch_timer.c +++ b/arch/arm/kernel/arch_timer.c @@ -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(+)