From 0ea415390cd345b7d09e8c9ebd4b68adfe873043 Mon Sep 17 00:00:00 2001
From: Marc Zyngier <marc.zyngier@arm.com>
Date: Mon, 8 Apr 2019 16:49:07 +0100
Subject: [PATCH] clocksource/arm_arch_timer: Use arch_timer_read_counter to
access stable counters
Instead of always going via arch_counter_get_cntvct_stable to access the
counter workaround, let's have arch_timer_read_counter point to the
right method.
For that, we need to track whether any CPU in the system has a
workaround for the counter. This is done by having an atomic variable
tracking this.
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
---
arch/arm/include/asm/arch_timer.h | 14 ++++++--
arch/arm64/include/asm/arch_timer.h | 16 ++++++++--
drivers/clocksource/arm_arch_timer.c | 48 +++++++++++++++++++++++++---
3 files changed, 70 insertions(+), 8 deletions(-)
diff --git a/arch/arm/include/asm/arch_timer.h b/arch/arm/include/asm/arch_timer.h
index 3f0a0191f763d..4b66ecd6be99d 100644
--- a/arch/arm/include/asm/arch_timer.h
+++ b/arch/arm/include/asm/arch_timer.h
@@ -83,7 +83,7 @@ static inline u32 arch_timer_get_cntfrq(void)
return val;
}
-static inline u64 arch_counter_get_cntpct(void)
+static inline u64 __arch_counter_get_cntpct(void)
{
u64 cval;
@@ -92,7 +92,12 @@ static inline u64 arch_counter_get_cntpct(void)
return cval;
}
-static inline u64 arch_counter_get_cntvct(void)
+static inline u64 __arch_counter_get_cntpct_stable(void)
+{
+ return __arch_counter_get_cntpct();
+}
+
+static inline u64 __arch_counter_get_cntvct(void)
{
u64 cval;
@@ -101,6 +106,11 @@ static inline u64 arch_counter_get_cntvct(void)
return cval;
}
+static inline u64 __arch_counter_get_cntvct_stable(void)
+{
+ return __arch_counter_get_cntvct();
+}
+
static inline u32 arch_timer_get_cntkctl(void)
{
u32 cntkctl;
diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h
index 5502ea049b63c..48b2100f4aaad 100644
--- a/arch/arm64/include/asm/arch_timer.h
+++ b/arch/arm64/include/asm/arch_timer.h
@@ -174,18 +174,30 @@ static inline void arch_timer_set_cntkctl(u32 cntkctl)
isb();
}
-static inline u64 arch_counter_get_cntpct(void)
+static inline u64 __arch_counter_get_cntpct_stable(void)
{
isb();
return arch_timer_reg_read_stable(cntpct_el0);
}
-static inline u64 arch_counter_get_cntvct(void)
+static inline u64 __arch_counter_get_cntpct(void)
+{
+ isb();
+ return read_sysreg(cntpct_el0);
+}
+
+static inline u64 __arch_counter_get_cntvct_stable(void)
{
isb();
return arch_timer_reg_read_stable(cntvct_el0);
}
+static inline u64 __arch_counter_get_cntvct(void)
+{
+ isb();
+ return read_sysreg(cntvct_el0);
+}
+
static inline int arch_timer_arch_init(void)
{
return 0;
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 8f22976247c00..27acc9eb0f7c4 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -152,6 +152,26 @@ u32 arch_timer_reg_read(int access, enum arch_timer_reg reg,
return val;
}
+static u64 arch_counter_get_cntpct_stable(void)
+{
+ return __arch_counter_get_cntpct_stable();
+}
+
+static u64 arch_counter_get_cntpct(void)
+{
+ return __arch_counter_get_cntpct();
+}
+
+static u64 arch_counter_get_cntvct_stable(void)
+{
+ return __arch_counter_get_cntvct_stable();
+}
+
+static u64 arch_counter_get_cntvct(void)
+{
+ return __arch_counter_get_cntvct();
+}
+
/*
* Default to cp15 based access because arm64 uses this function for
* sched_clock() before DT is probed and the cp15 method is guaranteed
@@ -365,6 +385,7 @@ static u32 notrace sun50i_a64_read_cntv_tval_el0(void)
DEFINE_PER_CPU(const struct arch_timer_erratum_workaround *, timer_unstable_counter_workaround);
EXPORT_SYMBOL_GPL(timer_unstable_counter_workaround);
+static atomic_t timer_unstable_counter_workaround_in_use = ATOMIC_INIT(0);
static void erratum_set_next_event_tval_generic(const int access, unsigned long evt,
struct clock_event_device *clk)
@@ -535,6 +556,9 @@ void arch_timer_enable_workaround(const struct arch_timer_erratum_workaround *wa
per_cpu(timer_unstable_counter_workaround, i) = wa;
}
+ if (wa->read_cntvct_el0 || wa->read_cntpct_el0)
+ atomic_set(&timer_unstable_counter_workaround_in_use, 1);
+
/*
* Don't use the vdso fastpath if errata require using the
* out-of-line counter accessor. We may change our mind pretty
@@ -591,9 +615,15 @@ static bool arch_timer_this_cpu_has_cntvct_wa(void)
{
return has_erratum_handler(read_cntvct_el0);
}
+
+static bool arch_timer_counter_has_wa(void)
+{
+ return atomic_read(&timer_unstable_counter_workaround_in_use);
+}
#else
#define arch_timer_check_ool_workaround(t,a) do { } while(0)
#define arch_timer_this_cpu_has_cntvct_wa() ({false;})
+#define arch_timer_counter_has_wa() ({false;})
#endif /* CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND */
static __always_inline irqreturn_t timer_handler(const int access,
@@ -942,12 +972,22 @@ static void __init arch_counter_register(unsigned type)
/* Register the CP15 based counter if we have one */
if (type & ARCH_TIMER_TYPE_CP15) {
+ u64 (*rd)(void);
+
if ((IS_ENABLED(CONFIG_ARM64) && !is_hyp_mode_available()) ||
- arch_timer_uses_ppi == ARCH_TIMER_VIRT_PPI)
- arch_timer_read_counter = arch_counter_get_cntvct;
- else
- arch_timer_read_counter = arch_counter_get_cntpct;
+ arch_timer_uses_ppi == ARCH_TIMER_VIRT_PPI) {
+ if (arch_timer_counter_has_wa())
+ rd = arch_counter_get_cntvct_stable;
+ else
+ rd = arch_counter_get_cntvct;
+ } else {
+ if (arch_timer_counter_has_wa())
+ rd = arch_counter_get_cntpct_stable;
+ else
+ rd = arch_counter_get_cntpct;
+ }
+ arch_timer_read_counter = rd;
clocksource_counter.archdata.vdso_direct = vdso_default;
} else {
arch_timer_read_counter = arch_counter_get_cntvct_mem;
--
2.30.2