Re: [PATCH] ARM: trace: Add tracepoint for the Inter ProcessorInterrupt

[Steven Rostedt]

On Mon, 14 Oct 2013 15:53:27 +0200
Daniel Lezcano <daniel.lezcano@xxxxxxxxxx> wrote:

> The Inter Processor Interrupt is used on ARM to tell another processor to do
> a specific action. This is mainly used to emulate a timer interrupt on an idle
> cpu, force a cpu to reschedule or run a function on another processor context.
> 
> Add a tracepoint when raising an IPI and in the entry/exit handler function.
> 
> Signed-off-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
> ---
>  arch/arm/include/asm/smp.h   |    9 ++++
>  arch/arm/kernel/smp.c        |   34 ++++++++------
>  arch/arm64/include/asm/smp.h |    7 +++
>  arch/arm64/kernel/smp.c      |   21 +++++++--
>  include/trace/events/ipi.h   |  106 ++++++++++++++++++++++++++++++++++++++++++
>  5 files changed, 158 insertions(+), 19 deletions(-)
>  create mode 100644 include/trace/events/ipi.h
> 
> diff --git a/arch/arm/include/asm/smp.h b/arch/arm/include/asm/smp.h
> index a8cae71c..788706c 100644
> --- a/arch/arm/include/asm/smp.h
> +++ b/arch/arm/include/asm/smp.h
> @@ -18,6 +18,15 @@
>  # error "<asm/smp.h> included in non-SMP build"
>  #endif
>  
> +enum ipi_msg_type {
> +	IPI_WAKEUP,
> +	IPI_TIMER,
> +	IPI_RESCHEDULE,
> +	IPI_CALL_FUNC,
> +	IPI_CALL_FUNC_SINGLE,
> +	IPI_CPU_STOP,
> +};
> +
>  #define raw_smp_processor_id() (current_thread_info()->cpu)
>  
>  struct seq_file;
> diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
> index 72024ea..9ca8ce8 100644
> --- a/arch/arm/kernel/smp.c
> +++ b/arch/arm/kernel/smp.c
> @@ -46,6 +46,9 @@
>  #include <asm/mach/arch.h>
>  #include <asm/mpu.h>
>  
> +#define CREATE_TRACE_POINTS
> +#include <trace/events/ipi.h>
> +
>  /*
>   * as from 2.5, kernels no longer have an init_tasks structure
>   * so we need some other way of telling a new secondary core
> @@ -59,15 +62,6 @@ struct secondary_data secondary_data;
>   */
>  volatile int pen_release = -1;
>  
> -enum ipi_msg_type {
> -	IPI_WAKEUP,
> -	IPI_TIMER,
> -	IPI_RESCHEDULE,
> -	IPI_CALL_FUNC,
> -	IPI_CALL_FUNC_SINGLE,
> -	IPI_CPU_STOP,
> -};
> -
>  static DECLARE_COMPLETION(cpu_running);
>  
>  static struct smp_operations smp_ops;
> @@ -433,19 +427,25 @@ void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
>  		smp_cross_call = fn;
>  }
>  
> +static void ipi_raise(const struct cpumask *mask, int ipinr)
> +{
> +	trace_ipi_raise(mask, ipinr);
> +	smp_cross_call(mask, ipinr);
> +}
> +
>  void arch_send_call_function_ipi_mask(const struct cpumask *mask)
>  {
> -	smp_cross_call(mask, IPI_CALL_FUNC);
> +	ipi_raise(mask, IPI_CALL_FUNC);
>  }
>  
>  void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
>  {
> -	smp_cross_call(mask, IPI_WAKEUP);
> +	ipi_raise(mask, IPI_WAKEUP);
>  }
>  
>  void arch_send_call_function_single_ipi(int cpu)
>  {
> -	smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
> +	ipi_raise(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
>  }
>  
>  static const char *ipi_types[NR_IPI] = {
> @@ -487,7 +487,7 @@ u64 smp_irq_stat_cpu(unsigned int cpu)
>  #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
>  void tick_broadcast(const struct cpumask *mask)
>  {
> -	smp_cross_call(mask, IPI_TIMER);
> +	ipi_raise(mask, IPI_TIMER);
>  }
>  #endif
>  
> @@ -528,6 +528,8 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
>  	unsigned int cpu = smp_processor_id();
>  	struct pt_regs *old_regs = set_irq_regs(regs);
>  
> +	trace_ipi_handler_entry(ipinr);
> +
>  	if (ipinr < NR_IPI)
>  		__inc_irq_stat(cpu, ipi_irqs[ipinr]);
>  
> @@ -571,11 +573,13 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
>  		break;
>  	}
>  	set_irq_regs(old_regs);
> +
> +	trace_ipi_handler_exit(ipinr);
>  }
>  
>  void smp_send_reschedule(int cpu)
>  {
> -	smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
> +	ipi_raise(cpumask_of(cpu), IPI_RESCHEDULE);
>  }
>  
>  void smp_send_stop(void)
> @@ -586,7 +590,7 @@ void smp_send_stop(void)
>  	cpumask_copy(&mask, cpu_online_mask);
>  	cpumask_clear_cpu(smp_processor_id(), &mask);
>  	if (!cpumask_empty(&mask))
> -		smp_cross_call(&mask, IPI_CPU_STOP);
> +		ipi_raise(&mask, IPI_CPU_STOP);
>  
>  	/* Wait up to one second for other CPUs to stop */
>  	timeout = USEC_PER_SEC;
> diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h
> index 4b8023c..7ebaa3a 100644
> --- a/arch/arm64/include/asm/smp.h
> +++ b/arch/arm64/include/asm/smp.h
> @@ -24,6 +24,13 @@
>  # error "<asm/smp.h> included in non-SMP build"
>  #endif
>  
> +enum ipi_msg_type {
> +	IPI_RESCHEDULE,
> +	IPI_CALL_FUNC,
> +	IPI_CALL_FUNC_SINGLE,
> +	IPI_CPU_STOP,
> +};
> +
>  #define raw_smp_processor_id() (current_thread_info()->cpu)
>  
>  struct seq_file;
> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index 78db90d..c987b9f 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -48,6 +48,9 @@
>  #include <asm/tlbflush.h>
>  #include <asm/ptrace.h>
>  
> +#define CREATE_TRACE_POINTS
> +#include <trace/events/ipi.h>
> +
>  /*
>   * as from 2.5, kernels no longer have an init_tasks structure
>   * so we need some other way of telling a new secondary core
> @@ -426,14 +429,20 @@ void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
>  	smp_cross_call = fn;
>  }
>  
> +static void ipi_raise(const struct cpumask *mask, int ipinr)
> +{
> +	trace_ipi_raise(mask, ipinr);
> +	smp_cross_call(mask, ipinr);
> +}
> +
>  void arch_send_call_function_ipi_mask(const struct cpumask *mask)
>  {
> -	smp_cross_call(mask, IPI_CALL_FUNC);
> +	ipi_raise(mask, IPI_CALL_FUNC);
>  }
>  
>  void arch_send_call_function_single_ipi(int cpu)
>  {
> -	smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
> +	ipi_raise(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
>  }
>  
>  static const char *ipi_types[NR_IPI] = {
> @@ -501,6 +510,8 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
>  	unsigned int cpu = smp_processor_id();
>  	struct pt_regs *old_regs = set_irq_regs(regs);
>  
> +	trace_ipi_handler_entry(ipinr);
> +
>  	if (ipinr >= IPI_RESCHEDULE && ipinr < IPI_RESCHEDULE + NR_IPI)
>  		__inc_irq_stat(cpu, ipi_irqs[ipinr - IPI_RESCHEDULE]);
>  
> @@ -532,11 +543,13 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
>  		break;
>  	}
>  	set_irq_regs(old_regs);
> +
> +	trace_ipi_handler_exit(ipinr);
>  }
>  
>  void smp_send_reschedule(int cpu)
>  {
> -	smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
> +	ipi_raise(cpumask_of(cpu), IPI_RESCHEDULE);
>  }
>  
>  void smp_send_stop(void)
> @@ -549,7 +562,7 @@ void smp_send_stop(void)
>  		cpumask_copy(&mask, cpu_online_mask);
>  		cpu_clear(smp_processor_id(), mask);
>  
> -		smp_cross_call(&mask, IPI_CPU_STOP);
> +		ipi_raise(&mask, IPI_CPU_STOP);
>  	}
>  
>  	/* Wait up to one second for other CPUs to stop */
> diff --git a/include/trace/events/ipi.h b/include/trace/events/ipi.h
> new file mode 100644
> index 0000000..4d6648a
> --- /dev/null
> +++ b/include/trace/events/ipi.h
> @@ -0,0 +1,106 @@
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM ipi
> +
> +#if !defined(_TRACE_IPI_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_IPI_H
> +
> +#include <linux/tracepoint.h>
> +
> +struct cpumask;
> +
> +#define ipi_name(ipinr) { IPI_##ipinr, #ipinr }
> +#define show_ipi_name(val)				\
> +	__print_symbolic(val,				\
> +			 ipi_name(WAKEUP),		\
> +			 ipi_name(TIMER),		\
> +			 ipi_name(RESCHEDULE),		\
> +			 ipi_name(CALL_FUNC),		\
> +			 ipi_name(CALL_FUNC_SINGLE),	\
> +			 ipi_name(CPU_STOP))
> +
> +/**
> + * ipi_handle_entry - called right before the IPI handler
> + * @ipinr: the IPI number
> + *
> + * The @ipinr value must be valid and the action name associated with
> + * the IPI value is given in the trace.
> + */
> +TRACE_EVENT_CONDITION(ipi_handler_entry,
> +
> +    TP_PROTO(int ipinr),
> +
> +    TP_ARGS(ipinr),
> +
> +    TP_CONDITION(ipinr < NR_IPI && ipinr >= 0),
> +
> +    TP_STRUCT__entry(
> +        __field(unsigned int, ipinr)
> +    ),
> +
> +    TP_fast_assign(
> +        __entry->ipinr = ipinr;
> +    ),
> +
> +    TP_printk("ipi=%d, name=%s", __entry->ipinr,
> +	      show_ipi_name(__entry->ipinr))
> +);
> +
> +/**
> + * ipi_handle_exit - called right after the IPI handler
> + * @ipinr: the IPI number
> + *
> + * The @ipinr value must be valid and the action name associated with
> + * the IPI value is given in the trace.
> + */
> +TRACE_EVENT_CONDITION(ipi_handler_exit,
> +
> +    TP_PROTO(int ipinr),
> +
> +    TP_ARGS(ipinr),
> +
> +    TP_CONDITION(ipinr < NR_IPI && ipinr >= 0),
> +
> +    TP_STRUCT__entry(
> +        __field(int, ipinr)

Here you have "int" and above for the "*_entry" you have unsigned int.
Is there a difference?

If not, you should combine these two into a DECLARE_EVENT_CLASS() and
then use DEFINE_EVENT_CONDITION() for the two tracepoints.

> +    ),
> +
> +    TP_fast_assign(
> +        __entry->ipinr = ipinr;
> +    ),
> +
> +    TP_printk("ipi=%d, name=%s", __entry->ipinr,
> +	      show_ipi_name(__entry->ipinr))
> +);
> +
> +/**
> + * ipi_raise - called when a smp cross call is made
> + * @ipinr: the IPI number
> + * @cpumask: the recipients for the IPI
> + *
> + * The @ipinr value must be valid and the action name associated with
> + * the IPI value is given in the trace.
> + */
> +TRACE_EVENT_CONDITION(ipi_raise,
> +
> +    TP_PROTO(const struct cpumask *cpumask, int ipinr),
> +
> +    TP_ARGS(cpumask, ipinr),

Why pass in the cpumask if it isn't used? Do you expect to hook
something else to the tracepoint?

-- Steve

> +
> +    TP_CONDITION(ipinr < NR_IPI && ipinr >= 0),
> +
> +    TP_STRUCT__entry(
> +        __field(int, ipinr)
> +    ),
> +
> +    TP_fast_assign(
> +        __entry->ipinr = ipinr;
> +    ),
> +
> +    TP_printk("ipi=%d, name=%s", __entry->ipinr, 
> +	      show_ipi_name(__entry->ipinr))
> +);
> +
> +#endif /* _TRACE_IPI_H */
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>

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