powerpc: Add doorbell tracepoints

When analysing sources of OS jitter, I noticed that doorbells cannot be
traced.

Signed-off-by: Anton Blanchard <anton@ozlabs.org>
---
 arch/powerpc/include/asm/trace.h | 16 ++++++++++++++++
 arch/powerpc/kernel/dbell.c      |  3 +++
 2 files changed, 19 insertions(+)

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
>

On Wed, 2018-10-03 at 10:29 +1000, Anton Blanchard wrote:
> When analysing sources of OS jitter, I noticed that doorbells cannot be
> traced.
> 
> Signed-off-by: Anton Blanchard <anton@ozlabs.org>

Hi Anton,

snowpatch builds failed for this patch on all 64-bit configurations (ppc64e, ppc64
and ppc64le) with the following:

arch/powerpc/kernel/dbell.c:85:9: error: undefined identifier
'trace_doorbell_entry'
arch/powerpc/kernel/dbell.c:96:9: error: undefined identifier
'trace_doorbell_exit'
./arch/powerpc/include/asm/spinlock.h:171:9: warning: context imbalance in
'key_user_put' - unexpected unlock
arch/powerpc/kernel/dbell.c: In function 'doorbell_exception':
arch/powerpc/kernel/dbell.c:85:2: error: implicit declaration of function
'trace_doorbell_entry'; did you mean 'trace_irq_entry'? [-Werror=implicit-
function-declaration]
  trace_doorbell_entry(regs);
  ^~~~~~~~~~~~~~~~~~~~
  trace_irq_entry
arch/powerpc/kernel/dbell.c:96:2: error: implicit declaration of function
'trace_doorbell_exit'; did you mean 'trace_irq_exit'? [-Werror=implicit-function-
declaration]
  trace_doorbell_exit(regs);
  ^~~~~~~~~~~~~~~~~~~
  trace_irq_exit
cc1: all warnings being treated as errors
scripts/Makefile.build:305: recipe for target 'arch/powerpc/kernel/dbell.o' failed
make[1]: *** [arch/powerpc/kernel/dbell.o] Error 1
Makefile:1060: recipe for target 'arch/powerpc/kernel' failed

So does something else need to check for CONFIG_PPC_DOORBELL maybe?

You can see the failures here: http://patchwork.ozlabs.org/patch/978088/ - output
in build_new.log (I know it's not pretty in there yet, you can search for "Error
1" to find the build failure)

- Russell

Hi Russell,

> snowpatch builds failed for this patch on all 64-bit configurations
> (ppc64e, ppc64 and ppc64le) with the following:

Thanks! Stupid bug on my part, need more quilt ref. Update to follow.

Anton

> arch/powerpc/kernel/dbell.c:85:9: error: undefined identifier
> 'trace_doorbell_entry'
> arch/powerpc/kernel/dbell.c:96:9: error: undefined identifier
> 'trace_doorbell_exit'
> ./arch/powerpc/include/asm/spinlock.h:171:9: warning: context
> imbalance in 'key_user_put' - unexpected unlock
> arch/powerpc/kernel/dbell.c: In function 'doorbell_exception':
> arch/powerpc/kernel/dbell.c:85:2: error: implicit declaration of
> function 'trace_doorbell_entry'; did you mean 'trace_irq_entry'?
> [-Werror=implicit- function-declaration]
>   trace_doorbell_entry(regs);
>   ^~~~~~~~~~~~~~~~~~~~
>   trace_irq_entry
> arch/powerpc/kernel/dbell.c:96:2: error: implicit declaration of
> function 'trace_doorbell_exit'; did you mean 'trace_irq_exit'?
> [-Werror=implicit-function- declaration]
>   trace_doorbell_exit(regs);
>   ^~~~~~~~~~~~~~~~~~~
>   trace_irq_exit
> cc1: all warnings being treated as errors
> scripts/Makefile.build:305: recipe for target
> 'arch/powerpc/kernel/dbell.o' failed make[1]: ***
> [arch/powerpc/kernel/dbell.o] Error 1 Makefile:1060: recipe for
> target 'arch/powerpc/kernel' failed
> 
> So does something else need to check for CONFIG_PPC_DOORBELL maybe?
> 
> You can see the failures here:
> http://patchwork.ozlabs.org/patch/978088/ - output in build_new.log
> (I know it's not pretty in there yet, you can search for "Error 1" to
> find the build failure)
> 
> - Russell
> 
>