Re: [Intel-gfx] [PATCH] drm/i915/gem: Poison stolen pages before use

[Mika Kuoppala <mika.kuoppala@linux.intel.com>]

Chris Wilson <chris@chris-wilson.co.uk> writes:

> When allocating objects from stolen, memset() the backing store to
> POISON_INUSE (0x5a) to help identify any uninitialised use of a stolen
> object.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>

> ---
>  drivers/gpu/drm/i915/gem/i915_gem_stolen.c | 33 ++++++++++++++++++++++
>  1 file changed, 33 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_stolen.c b/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
> index 0be5e8683337..4c2869c0a802 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
> @@ -572,6 +572,38 @@ static const struct drm_i915_gem_object_ops i915_gem_object_stolen_ops = {
>  	.release = i915_gem_object_release_stolen,
>  };
>  
> +static void dbg_poison(struct drm_i915_gem_object *obj)
> +{
> +#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)
> +	struct drm_i915_private *i915 = to_i915(obj->base.dev);
> +	struct i915_ggtt *ggtt = &i915->ggtt;
> +	struct sgt_iter iter;
> +	dma_addr_t addr;
> +
> +	if (!drm_mm_node_allocated(&ggtt->error_capture))
> +		return;
> +
> +	mutex_lock(&ggtt->error_mutex);
> +	for_each_sgt_daddr(addr, iter, obj->mm.pages) {
> +		void __iomem *s;
> +
> +		ggtt->vm.insert_page(&ggtt->vm, addr,
> +				     ggtt->error_capture.start,
> +				     I915_CACHE_NONE, 0);
> +		mb();
> +
> +		s = io_mapping_map_wc(&ggtt->iomap,
> +				      ggtt->error_capture.start,
> +				      PAGE_SIZE);
> +		memset(s, POISON_INUSE, PAGE_SIZE);
> +		io_mapping_unmap(s);
> +	}
> +	mb();
> +	ggtt->vm.clear_range(&ggtt->vm, ggtt->error_capture.start, PAGE_SIZE);
> +	mutex_unlock(&ggtt->error_mutex);
> +#endif
> +}
> +
>  static struct drm_i915_gem_object *
>  __i915_gem_object_create_stolen(struct intel_memory_region *mem,
>  				struct drm_mm_node *stolen)
> @@ -598,6 +630,7 @@ __i915_gem_object_create_stolen(struct intel_memory_region *mem,
>  		goto cleanup;
>  
>  	i915_gem_object_init_memory_region(obj, mem, 0);
> +	dbg_poison(obj);
>  
>  	return obj;
>  
> -- 
> 2.20.1
>
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