From mboxrd@z Thu Jan 1 00:00:00 1970 From: mark.rutland@arm.com (Mark Rutland) Date: Wed, 19 Dec 2012 15:11:07 +0000 Subject: [PATCHv2 08/11] arm: arch_timer: add arch_counter_set_user_access In-Reply-To: <1355929870-30252-1-git-send-email-mark.rutland@arm.com> References: <1355929870-30252-1-git-send-email-mark.rutland@arm.com> Message-ID: <1355929870-30252-9-git-send-email-mark.rutland@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Several bits in CNTKCTL reset to 0, including PL0VTEN. For platforms using the generic timer which wish to have a fast gettimeofday vDSO implementation, these bits must be set to 1 by the kernel. On other platforms, the bootloader might enable userspace access when we don't want it. This patch adds arch_counter_set_user_access, which sets the PL0 access permissions to that required by the platform. For arm, this currently means disabling all userspace access. Signed-off-by: Mark Rutland --- arch/arm/include/asm/arch_timer.h | 11 +++++++++++ arch/arm/kernel/arch_timer.c | 2 ++ 2 files changed, 13 insertions(+), 0 deletions(-) diff --git a/arch/arm/include/asm/arch_timer.h b/arch/arm/include/asm/arch_timer.h index 701f2b7..05e3593 100644 --- a/arch/arm/include/asm/arch_timer.h +++ b/arch/arm/include/asm/arch_timer.h @@ -108,6 +108,17 @@ static inline u64 arch_counter_get_cntvct(void) 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 834d347..4f39e68 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; } -- 1.7.0.4