Re: [PATCH v3 2/7] arm_pmu: Change API to support 64bit counter values

[Mark Rutland]

On Tue, Jun 19, 2018 at 11:15:37AM +0100, Suzuki K Poulose wrote:
> Convert the {read/write}_counter APIs to handle 64bit values
> to enable supporting chained event counters.

It might be worth a note that the underlying helpers will still only
write 32-bit values, and we'll only pass those 32-bit values, so this
shouldn't cause any functional change.

> 
> Cc: Mark Rutland <mark.rutland@xxxxxxx>
> Cc: Will Deacon <will.deacon@xxxxxxx>
> Reviewed-by: Julien Thierry <julien.thierry@xxxxxxx>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>

Acked-by: Mark Rutland <mark.rutland@xxxxxxx>

Mark.

> ---
>  - No changes since v2
> ---
>  arch/arm/kernel/perf_event_v6.c     | 4 ++--
>  arch/arm/kernel/perf_event_v7.c     | 4 ++--
>  arch/arm/kernel/perf_event_xscale.c | 8 ++++----
>  arch/arm64/kernel/perf_event.c      | 9 ++++-----
>  include/linux/perf/arm_pmu.h        | 4 ++--
>  5 files changed, 14 insertions(+), 15 deletions(-)
> 
> diff --git a/arch/arm/kernel/perf_event_v6.c b/arch/arm/kernel/perf_event_v6.c
> index f64a6bf..0729f98 100644
> --- a/arch/arm/kernel/perf_event_v6.c
> +++ b/arch/arm/kernel/perf_event_v6.c
> @@ -233,7 +233,7 @@ armv6_pmcr_counter_has_overflowed(unsigned long pmcr,
>  	return ret;
>  }
>  
> -static inline u32 armv6pmu_read_counter(struct perf_event *event)
> +static inline u64 armv6pmu_read_counter(struct perf_event *event)
>  {
>  	struct hw_perf_event *hwc = &event->hw;
>  	int counter = hwc->idx;
> @@ -251,7 +251,7 @@ static inline u32 armv6pmu_read_counter(struct perf_event *event)
>  	return value;
>  }
>  
> -static inline void armv6pmu_write_counter(struct perf_event *event, u32 value)
> +static inline void armv6pmu_write_counter(struct perf_event *event, u64 value)
>  {
>  	struct hw_perf_event *hwc = &event->hw;
>  	int counter = hwc->idx;
> diff --git a/arch/arm/kernel/perf_event_v7.c b/arch/arm/kernel/perf_event_v7.c
> index ecca4cd..fd7ce01 100644
> --- a/arch/arm/kernel/perf_event_v7.c
> +++ b/arch/arm/kernel/perf_event_v7.c
> @@ -743,7 +743,7 @@ static inline void armv7_pmnc_select_counter(int idx)
>  	isb();
>  }
>  
> -static inline u32 armv7pmu_read_counter(struct perf_event *event)
> +static inline u64 armv7pmu_read_counter(struct perf_event *event)
>  {
>  	struct arm_pmu *cpu_pmu = to_arm_pmu(event->pmu);
>  	struct hw_perf_event *hwc = &event->hw;
> @@ -763,7 +763,7 @@ static inline u32 armv7pmu_read_counter(struct perf_event *event)
>  	return value;
>  }
>  
> -static inline void armv7pmu_write_counter(struct perf_event *event, u32 value)
> +static inline void armv7pmu_write_counter(struct perf_event *event, u64 value)
>  {
>  	struct arm_pmu *cpu_pmu = to_arm_pmu(event->pmu);
>  	struct hw_perf_event *hwc = &event->hw;
> diff --git a/arch/arm/kernel/perf_event_xscale.c b/arch/arm/kernel/perf_event_xscale.c
> index c4f0294..942230f 100644
> --- a/arch/arm/kernel/perf_event_xscale.c
> +++ b/arch/arm/kernel/perf_event_xscale.c
> @@ -316,7 +316,7 @@ static void xscale1pmu_stop(struct arm_pmu *cpu_pmu)
>  	raw_spin_unlock_irqrestore(&events->pmu_lock, flags);
>  }
>  
> -static inline u32 xscale1pmu_read_counter(struct perf_event *event)
> +static inline u64 xscale1pmu_read_counter(struct perf_event *event)
>  {
>  	struct hw_perf_event *hwc = &event->hw;
>  	int counter = hwc->idx;
> @@ -337,7 +337,7 @@ static inline u32 xscale1pmu_read_counter(struct perf_event *event)
>  	return val;
>  }
>  
> -static inline void xscale1pmu_write_counter(struct perf_event *event, u32 val)
> +static inline void xscale1pmu_write_counter(struct perf_event *event, u64 val)
>  {
>  	struct hw_perf_event *hwc = &event->hw;
>  	int counter = hwc->idx;
> @@ -678,7 +678,7 @@ static void xscale2pmu_stop(struct arm_pmu *cpu_pmu)
>  	raw_spin_unlock_irqrestore(&events->pmu_lock, flags);
>  }
>  
> -static inline u32 xscale2pmu_read_counter(struct perf_event *event)
> +static inline u64 xscale2pmu_read_counter(struct perf_event *event)
>  {
>  	struct hw_perf_event *hwc = &event->hw;
>  	int counter = hwc->idx;
> @@ -705,7 +705,7 @@ static inline u32 xscale2pmu_read_counter(struct perf_event *event)
>  	return val;
>  }
>  
> -static inline void xscale2pmu_write_counter(struct perf_event *event, u32 val)
> +static inline void xscale2pmu_write_counter(struct perf_event *event, u64 val)
>  {
>  	struct hw_perf_event *hwc = &event->hw;
>  	int counter = hwc->idx;
> diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
> index 678ecff..66a2ffd 100644
> --- a/arch/arm64/kernel/perf_event.c
> +++ b/arch/arm64/kernel/perf_event.c
> @@ -512,7 +512,7 @@ static inline int armv8pmu_select_counter(int idx)
>  	return idx;
>  }
>  
> -static inline u32 armv8pmu_read_counter(struct perf_event *event)
> +static inline u64 armv8pmu_read_counter(struct perf_event *event)
>  {
>  	struct arm_pmu *cpu_pmu = to_arm_pmu(event->pmu);
>  	struct hw_perf_event *hwc = &event->hw;
> @@ -530,7 +530,7 @@ static inline u32 armv8pmu_read_counter(struct perf_event *event)
>  	return value;
>  }
>  
> -static inline void armv8pmu_write_counter(struct perf_event *event, u32 value)
> +static inline void armv8pmu_write_counter(struct perf_event *event, u64 value)
>  {
>  	struct arm_pmu *cpu_pmu = to_arm_pmu(event->pmu);
>  	struct hw_perf_event *hwc = &event->hw;
> @@ -545,9 +545,8 @@ static inline void armv8pmu_write_counter(struct perf_event *event, u32 value)
>  		 * count using the lower 32bits and we want an interrupt when
>  		 * it overflows.
>  		 */
> -		u64 value64 = 0xffffffff00000000ULL | value;
> -
> -		write_sysreg(value64, pmccntr_el0);
> +		value |= 0xffffffff00000000ULL;
> +		write_sysreg(value, pmccntr_el0);
>  	} else if (armv8pmu_select_counter(idx) == idx)
>  		write_sysreg(value, pmxevcntr_el0);
>  }
> diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h
> index 12c30a2..f7126a2 100644
> --- a/include/linux/perf/arm_pmu.h
> +++ b/include/linux/perf/arm_pmu.h
> @@ -87,8 +87,8 @@ struct arm_pmu {
>  					 struct perf_event *event);
>  	int		(*set_event_filter)(struct hw_perf_event *evt,
>  					    struct perf_event_attr *attr);
> -	u32		(*read_counter)(struct perf_event *event);
> -	void		(*write_counter)(struct perf_event *event, u32 val);
> +	u64		(*read_counter)(struct perf_event *event);
> +	void		(*write_counter)(struct perf_event *event, u64 val);
>  	void		(*start)(struct arm_pmu *);
>  	void		(*stop)(struct arm_pmu *);
>  	void		(*reset)(void *);
> -- 
> 2.7.4
>