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Subject[RFC 3/6] arm/arm64: clocksource: Introduce vclock_mode
Date
Similar to x86, use a vclock_mode in arch_clocksource_data to differ
clocksoures use different read function in vDSO.

No functional changes, only preparation for support vDSO in ARM64 on
Hyper-V.

Note: the changes for arm are only because arm and arm64 share the same
code in the arch timer driver and require arch_clocksource_data having
the same field.

Signed-off-by: Boqun Feng (Microsoft) <boqun.feng@gmail.com>
---
arch/arm/include/asm/clocksource.h | 6 +++++-
arch/arm/kernel/vdso.c | 1 -
arch/arm64/include/asm/clocksource.h | 6 +++++-
arch/arm64/include/asm/mshyperv.h | 2 +-
arch/arm64/include/asm/vdso/compat_gettimeofday.h | 5 +++--
arch/arm64/include/asm/vdso/gettimeofday.h | 5 +++--
arch/arm64/include/asm/vdso/vsyscall.h | 4 +---
drivers/clocksource/arm_arch_timer.c | 8 ++++----
8 files changed, 22 insertions(+), 15 deletions(-)

diff --git a/arch/arm/include/asm/clocksource.h b/arch/arm/include/asm/clocksource.h
index 0b350a7e26f3..017c5ab6e587 100644
--- a/arch/arm/include/asm/clocksource.h
+++ b/arch/arm/include/asm/clocksource.h
@@ -1,8 +1,12 @@
#ifndef _ASM_CLOCKSOURCE_H
#define _ASM_CLOCKSOURCE_H

+#define VCLOCK_NONE 0 /* No vDSO clock available. */
+#define VCLOCK_CNTVCT 1 /* vDSO should use cntvcnt */
+#define VCLOCK_MAX 1
+
struct arch_clocksource_data {
- bool vdso_direct; /* Usable for direct VDSO access? */
+ int vclock_mode;
};

#endif
diff --git a/arch/arm/kernel/vdso.c b/arch/arm/kernel/vdso.c
index c89ac1b9d28b..09e46ec420fe 100644
--- a/arch/arm/kernel/vdso.c
+++ b/arch/arm/kernel/vdso.c
@@ -263,4 +263,3 @@ void arm_install_vdso(struct mm_struct *mm, unsigned long addr)
if (!IS_ERR(vma))
mm->context.vdso = addr;
}
-
diff --git a/arch/arm64/include/asm/clocksource.h b/arch/arm64/include/asm/clocksource.h
index 0ece64a26c8c..fbe80057468c 100644
--- a/arch/arm64/include/asm/clocksource.h
+++ b/arch/arm64/include/asm/clocksource.h
@@ -2,8 +2,12 @@
#ifndef _ASM_CLOCKSOURCE_H
#define _ASM_CLOCKSOURCE_H

+#define VCLOCK_NONE 0 /* No vDSO clock available. */
+#define VCLOCK_CNTVCT 1 /* vDSO should use cntvcnt */
+#define VCLOCK_MAX 1
+
struct arch_clocksource_data {
- bool vdso_direct; /* Usable for direct VDSO access? */
+ int vclock_mode;
};

#endif
diff --git a/arch/arm64/include/asm/mshyperv.h b/arch/arm64/include/asm/mshyperv.h
index 9cc4aeddf2d0..0afb00e3501d 100644
--- a/arch/arm64/include/asm/mshyperv.h
+++ b/arch/arm64/include/asm/mshyperv.h
@@ -90,7 +90,7 @@ extern void hv_get_vpreg_128(u32 reg, struct hv_get_vp_register_output *result);
#define hv_set_reference_tsc(val) \
hv_set_vpreg(HV_REGISTER_REFERENCE_TSC, val)
#define hv_set_clocksource_vdso(val) \
- ((val).archdata.vdso_direct = false)
+ ((val).archdata.vclock_mode = VCLOCK_NONE)

#if IS_ENABLED(CONFIG_HYPERV)
#define hv_enable_stimer0_percpu_irq(irq) enable_percpu_irq(irq, 0)
diff --git a/arch/arm64/include/asm/vdso/compat_gettimeofday.h b/arch/arm64/include/asm/vdso/compat_gettimeofday.h
index c50ee1b7d5cd..630d04c3c92e 100644
--- a/arch/arm64/include/asm/vdso/compat_gettimeofday.h
+++ b/arch/arm64/include/asm/vdso/compat_gettimeofday.h
@@ -8,6 +8,7 @@
#ifndef __ASSEMBLY__

#include <asm/unistd.h>
+#include <asm/clocksource.h>
#include <uapi/linux/time.h>

#include <asm/vdso/compat_barrier.h>
@@ -117,10 +118,10 @@ static __always_inline u64 __arch_get_hw_counter(s32 clock_mode)
u64 res;

/*
- * clock_mode == 0 implies that vDSO are enabled otherwise
+ * clock_mode == VCLOCK_NONE implies that vDSO are disabled so
* fallback on syscall.
*/
- if (clock_mode)
+ if (clock_mode == VCLOCK_NONE)
return __VDSO_USE_SYSCALL;

/*
diff --git a/arch/arm64/include/asm/vdso/gettimeofday.h b/arch/arm64/include/asm/vdso/gettimeofday.h
index b08f476b72b4..e6e3fe0488c7 100644
--- a/arch/arm64/include/asm/vdso/gettimeofday.h
+++ b/arch/arm64/include/asm/vdso/gettimeofday.h
@@ -8,6 +8,7 @@
#ifndef __ASSEMBLY__

#include <asm/unistd.h>
+#include <asm/clocksource.h>
#include <uapi/linux/time.h>

#define __VDSO_USE_SYSCALL ULLONG_MAX
@@ -71,10 +72,10 @@ static __always_inline u64 __arch_get_hw_counter(s32 clock_mode)
u64 res;

/*
- * clock_mode == 0 implies that vDSO are enabled otherwise
+ * clock_mode == VCLOCK_NONE implies that vDSO are disabled so
* fallback on syscall.
*/
- if (clock_mode)
+ if (clock_mode == VCLOCK_NONE)
return __VDSO_USE_SYSCALL;

/*
diff --git a/arch/arm64/include/asm/vdso/vsyscall.h b/arch/arm64/include/asm/vdso/vsyscall.h
index 0c20a7c1bee5..07f78b0da498 100644
--- a/arch/arm64/include/asm/vdso/vsyscall.h
+++ b/arch/arm64/include/asm/vdso/vsyscall.h
@@ -24,9 +24,7 @@ struct vdso_data *__arm64_get_k_vdso_data(void)
static __always_inline
int __arm64_get_clock_mode(struct timekeeper *tk)
{
- u32 use_syscall = !tk->tkr_mono.clock->archdata.vdso_direct;
-
- return use_syscall;
+ return tk->tkr_mono.clock->archdata.vclock_mode;
}
#define __arch_get_clock_mode __arm64_get_clock_mode

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 9a5464c625b4..9b8d4d00b53b 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -69,7 +69,7 @@ static enum arch_timer_ppi_nr arch_timer_uses_ppi = ARCH_TIMER_VIRT_PPI;
static bool arch_timer_c3stop;
static bool arch_timer_mem_use_virtual;
static bool arch_counter_suspend_stop;
-static bool vdso_default = true;
+static int vdso_default = VCLOCK_CNTVCT;

static cpumask_t evtstrm_available = CPU_MASK_NONE;
static bool evtstrm_enable = IS_ENABLED(CONFIG_ARM_ARCH_TIMER_EVTSTREAM);
@@ -560,8 +560,8 @@ void arch_timer_enable_workaround(const struct arch_timer_erratum_workaround *wa
* change both the default value and the vdso itself.
*/
if (wa->read_cntvct_el0) {
- clocksource_counter.archdata.vdso_direct = false;
- vdso_default = false;
+ clocksource_counter.archdata.vclock_mode = VCLOCK_NONE;
+ vdso_default = VCLOCK_NONE;
}
}

@@ -979,7 +979,7 @@ static void __init arch_counter_register(unsigned type)
}

arch_timer_read_counter = rd;
- clocksource_counter.archdata.vdso_direct = vdso_default;
+ clocksource_counter.archdata.vclock_mode = vdso_default;
} else {
arch_timer_read_counter = arch_counter_get_cntvct_mem;
}
--
2.24.0
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