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authorWill Deacon <will.deacon@arm.com>2012-11-29 22:48:31 +0000
committerCatalin Marinas <catalin.marinas@arm.com>2012-12-05 11:20:04 +0000
commit1f75ff0a3d63606c1345e316e88a903fd43ca8be (patch)
treed326cb2f58040c910390e80f5a5287b0074a0276
parent45a7905fc48f6079932e77d64237cf7f008db5f4 (diff)
downloadblackbird-op-linux-1f75ff0a3d63606c1345e316e88a903fd43ca8be.tar.gz
blackbird-op-linux-1f75ff0a3d63606c1345e316e88a903fd43ca8be.zip
arm64: generic timer: use virtual counter instead of physical at EL0
We want to use the virtual counter at EL0, as the physical counter may not track the current clocksource for guests running under a hypervisor. This patch updates the vdso and generic timer driver to use the virtual counter. The kernel EL2 entry code is also updated to ensure that the virtual offset is initialised to zero. Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
-rw-r--r--arch/arm64/include/asm/arm_generic.h8
-rw-r--r--arch/arm64/kernel/head.S1
-rw-r--r--arch/arm64/kernel/vdso/gettimeofday.S4
-rw-r--r--drivers/clocksource/arm_generic.c2
4 files changed, 8 insertions, 7 deletions
diff --git a/arch/arm64/include/asm/arm_generic.h b/arch/arm64/include/asm/arm_generic.h
index e4cec9d30f27..df2aeb82f74e 100644
--- a/arch/arm64/include/asm/arm_generic.h
+++ b/arch/arm64/include/asm/arm_generic.h
@@ -70,12 +70,12 @@ static inline void __cpuinit arch_counter_enable_user_access(void)
{
u32 cntkctl;
- /* Disable user access to the timers and the virtual counter. */
+ /* Disable user access to the timers and the physical counter. */
asm volatile("mrs %0, cntkctl_el1" : "=r" (cntkctl));
- cntkctl &= ~((3 << 8) | (1 << 1));
+ cntkctl &= ~((3 << 8) | (1 << 0));
- /* Enable user access to the physical counter and frequency. */
- cntkctl |= 1;
+ /* Enable user access to the virtual counter and frequency. */
+ cntkctl |= (1 << 1);
asm volatile("msr cntkctl_el1, %0" : : "r" (cntkctl));
}
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index a2f02b63eae9..90dec55b17a2 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -158,6 +158,7 @@ ENTRY(el2_setup)
mrs x0, cnthctl_el2
orr x0, x0, #3 // Enable EL1 physical timers
msr cnthctl_el2, x0
+ msr cntvoff_el2, xzr // Clear virtual offset
/* Populate ID registers. */
mrs x0, midr_el1
diff --git a/arch/arm64/kernel/vdso/gettimeofday.S b/arch/arm64/kernel/vdso/gettimeofday.S
index 6681f4032260..8bf658d974f9 100644
--- a/arch/arm64/kernel/vdso/gettimeofday.S
+++ b/arch/arm64/kernel/vdso/gettimeofday.S
@@ -220,9 +220,9 @@ ENTRY(__do_get_tspec)
ldp w11, w12, [vdso_data, #VDSO_CS_MULT]
seqcnt_read w9
- /* Read the physical counter. */
+ /* Read the virtual counter. */
isb
- mrs x15, cntpct_el0
+ mrs x15, cntvct_el0
/* Calculate cycle delta and convert to ns. */
sub x10, x15, x10
diff --git a/drivers/clocksource/arm_generic.c b/drivers/clocksource/arm_generic.c
index c4d9f9566c64..df5d7e8e5b84 100644
--- a/drivers/clocksource/arm_generic.c
+++ b/drivers/clocksource/arm_generic.c
@@ -109,7 +109,7 @@ static void __cpuinit arch_timer_setup(struct clock_event_device *clk)
enable_percpu_irq(clk->irq, 0);
- /* Ensure the physical counter is visible to userspace for the vDSO. */
+ /* Ensure the virtual counter is visible to userspace for the vDSO. */
arch_counter_enable_user_access();
}
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