Re: [PATCH 3/3] drm/i915: Trace point callbacks for validation

[Daniel Vetter <daniel@ffwll.ch>]

On Tue, Jul 01, 2014 at 05:24:23PM +0100, daniele.ceraolospurio@intel.com wrote:
> From: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
> 
> These callbacks can be assigned to specific functions inside an external
> validation kernel module. This module can then extract run-time
> information to make sure everything is working as expected.
> 
> Specifically, these two callbacks extract information about full PPGTT
> and batch dispatch.
> 
> Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_gem_context.c    |  3 +++
>  drivers/gpu/drm/i915/i915_gem_execbuffer.c |  3 +++
>  drivers/gpu/drm/i915/i915_trace.h          | 22 ++++++++++++++++++++++
>  3 files changed, 28 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
> index 99f7022..120a319 100644
> --- a/drivers/gpu/drm/i915/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/i915_gem_context.c
> @@ -90,6 +90,9 @@
>  #include "i915_drv.h"
>  #include "i915_trace.h"
>  
> +i915_ppgtt_validation_callback_t ppgtt_validation_callback = NULL;
> +EXPORT_SYMBOL_GPL(ppgtt_validation_callback);
> +
>  /* This is a HW constraint. The value below is the largest known requirement
>   * I've seen in a spec to date, and that was a workaround for a non-shipping
>   * part. It should be safe to decrease this, but it's more future proof as is.
> diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> index 0b2b76e..7feb977 100644
> --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> @@ -33,6 +33,9 @@
>  #include "intel_drv.h"
>  #include <linux/dma_remapping.h>
>  
> +i915_gem_ring_dispatch_callback_t i915_gem_ring_dispatch_validation_callback = NULL;
> +EXPORT_SYMBOL_GPL(i915_gem_ring_dispatch_validation_callback);
> +
>  #define  __EXEC_OBJECT_HAS_PIN (1<<31)
>  #define  __EXEC_OBJECT_HAS_FENCE (1<<30)
>  #define  __EXEC_OBJECT_NEEDS_BIAS (1<<28)
> diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h
> index 4e73e3a..98c6f47 100644
> --- a/drivers/gpu/drm/i915/i915_trace.h
> +++ b/drivers/gpu/drm/i915/i915_trace.h
> @@ -15,6 +15,18 @@
>  #define TRACE_SYSTEM_STRING __stringify(TRACE_SYSTEM)
>  #define TRACE_INCLUDE_FILE i915_trace
>  
> +/* validation callbacks */
> +
> +typedef void (*i915_ppgtt_validation_callback_t)(unsigned int action_code,
> +						 struct i915_hw_ppgtt *ppgtt);
> +extern i915_ppgtt_validation_callback_t ppgtt_validation_callback;
> +
> +typedef void (*i915_gem_ring_dispatch_callback_t)(struct intel_engine_cs *ring,
> +						  u32 seqno,
> +						  u32 flags,
> +						  struct intel_context *ctx);
> +extern i915_gem_ring_dispatch_callback_t i915_gem_ring_dispatch_validation_callback;
> +
>  /* pipe updates */
>  
>  TRACE_EVENT(i915_pipe_update_start,
> @@ -371,6 +383,10 @@ TRACE_EVENT(i915_gem_ring_dispatch,
>  			   __entry->flags = flags;
>  			   __entry->vm = ctx->vm;
>  			   i915_trace_irq_get(ring, seqno);
> +
> +			   if (i915_gem_ring_dispatch_validation_callback)
> +				   i915_gem_ring_dispatch_validation_callback(ring,
> +						      seqno, flags, ctx);

Nack on two grounds:
- I already get flames for the irq_get in here from the tracepoint
  maintainer - he really doesn't like us adding randome stuff with
  side-effects here.
- If we want extended validation interfaces we should upstream those, not
  just the hooks.

Cheers, Daniel

>  			   ),
>  
>  	    TP_printk("dev=%u, ring=%u, seqno=%u, flags=%x, vm=%p",
> @@ -607,6 +623,9 @@ TRACE_EVENT(create_vm_for_ctx,
>  			__entry->vm = &ppgtt->base;
>  			__entry->dev = ppgtt->base.dev->primary->index;
>  			__entry->pid = (unsigned int)task_pid_nr(current);
> +
> +			if (ppgtt_validation_callback)
> +				ppgtt_validation_callback(0, ppgtt);
>  	),
>  
>  	TP_printk("dev=%u, task_pid=%u, vm=%p",
> @@ -627,6 +646,9 @@ TRACE_EVENT(ppgtt_release,
>  	TP_fast_assign(
>  		__entry->vm = &ppgtt->base;
>  		__entry->dev = ppgtt->base.dev->primary->index;
> +
> +		if (ppgtt_validation_callback)
> +			ppgtt_validation_callback(1, ppgtt);
>  	),
>  
>  	TP_printk("dev=%u, vm=%p", __entry->dev, __entry->vm)
> -- 
> 1.8.5.2
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch