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| author | Mark Rutland <mark.rutland@arm.com> | 2012-11-14 10:32:24 (GMT) |
|---|---|---|
| committer | Mark Rutland <mark.rutland@arm.com> | 2013-01-31 15:51:39 (GMT) |
| commit | b2deabe3ba664a1ec47400c0ca285e951874e0cc (patch) | |
| tree | f23f2dfe4abb6d10a40801edbaf227d21cb31471 /arch/arm/include | |
| parent | 1ba1cefc277865a0ac222f53bbbf2ebacad1559a (diff) | |
| download | linux-b2deabe3ba664a1ec47400c0ca285e951874e0cc.tar.xz | |
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 <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm/include')
| -rw-r--r-- | arch/arm/include/asm/arch_timer.h | 12 |
1 files changed, 12 insertions, 0 deletions
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) { |