Re: [PATCH] powerpc: Add doorbell tracepoints

[Nicholas Piggin <npiggin@gmail.com>]

On Wed,  3 Oct 2018 10:29:57 +1000
Anton Blanchard <anton@ozlabs.org> wrote:

> When analysing sources of OS jitter, I noticed that doorbells cannot be
> traced.
> 
> Signed-off-by: Anton Blanchard <anton@ozlabs.org>

Acked-by: Nicholas Piggin <npiggin@gmail.com>

> ---
>  arch/powerpc/include/asm/trace.h | 16 ++++++++++++++++
>  arch/powerpc/kernel/dbell.c      |  3 +++
>  2 files changed, 19 insertions(+)
> 
> diff --git a/arch/powerpc/include/asm/trace.h b/arch/powerpc/include/asm/trace.h
> index d018e8602694..eb9aa0f1561e 100644
> --- a/arch/powerpc/include/asm/trace.h
> +++ b/arch/powerpc/include/asm/trace.h
> @@ -54,6 +54,22 @@ DEFINE_EVENT(ppc64_interrupt_class, timer_interrupt_exit,
>  	TP_ARGS(regs)
>  );
>  
> +#ifdef CONFIG_PPC_DOORBELL
> +DEFINE_EVENT(ppc64_interrupt_class, doorbell_exception_entry,
> +
> +	TP_PROTO(struct pt_regs *regs),
> +
> +	TP_ARGS(regs)
> +);
> +
> +DEFINE_EVENT(ppc64_interrupt_class, doorbell_exception_exit,
> +
> +	TP_PROTO(struct pt_regs *regs),
> +
> +	TP_ARGS(regs)
> +);
> +#endif
> +
>  #ifdef CONFIG_PPC_PSERIES
>  extern int hcall_tracepoint_regfunc(void);
>  extern void hcall_tracepoint_unregfunc(void);
> diff --git a/arch/powerpc/kernel/dbell.c b/arch/powerpc/kernel/dbell.c
> index b6fe883b1016..5ec3b3835925 100644
> --- a/arch/powerpc/kernel/dbell.c
> +++ b/arch/powerpc/kernel/dbell.c
> @@ -18,6 +18,7 @@
>  #include <asm/dbell.h>
>  #include <asm/irq_regs.h>
>  #include <asm/kvm_ppc.h>
> +#include <asm/trace.h>
>  
>  #ifdef CONFIG_SMP
>  
> @@ -81,6 +82,7 @@ void doorbell_exception(struct pt_regs *regs)
>  	struct pt_regs *old_regs = set_irq_regs(regs);
>  
>  	irq_enter();
> +	trace_doorbell_entry(regs);
>  
>  	ppc_msgsync();
>  
> @@ -91,6 +93,7 @@ void doorbell_exception(struct pt_regs *regs)
>  
>  	smp_ipi_demux_relaxed(); /* already performed the barrier */
>  
> +	trace_doorbell_exit(regs);
>  	irq_exit();
>  	set_irq_regs(old_regs);
>  }
> -- 
> 2.17.1
>