From 0ea415390cd345b7d09e8c9ebd4b68adfe873043 Mon Sep 17 00:00:00 2001 From: Marc Zyngier 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 Signed-off-by: Marc Zyngier Signed-off-by: Will Deacon --- arch/arm/include/asm/arch_timer.h | 14 ++++++-- arch/arm64/include/asm/arch_timer.h | 16 +++++++-- drivers/clocksource/arm_arch_timer.c | 50 +++++++++++++++++++++++++--- 3 files changed, 71 insertions(+), 9 deletions(-) diff --git a/arch/arm/include/asm/arch_timer.h b/arch/arm/include/asm/arch_timer.h index 3f0a0191f763..4b66ecd6be99 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 5502ea049b63..48b2100f4aaa 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 8f22976247c0..27acc9eb0f7c 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) { - 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; + u64 (*rd)(void); + if ((IS_ENABLED(CONFIG_ARM64) && !is_hyp_mode_available()) || + 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;