drm/i915: Record error batch buffers using iomem

Directly read the GTT mapping for the contents of the batch buffers
rather than relying on possibly stale CPU caches. Also for completeness
scan the flushing/inactive lists for the current buffers - we are
collecting error state after all.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Eric Anholt <eric@anholt.net>

drivers/gpu/drm/i915/i915_irq.c

@@ -425,9 +425,11 @@ static struct drm_i915_error_object *
 i915_error_object_create(struct drm_device *dev,
 			 struct drm_gem_object *src)
 {
+	drm_i915_private_t *dev_priv = dev->dev_private;
 	struct drm_i915_error_object *dst;
 	struct drm_i915_gem_object *src_priv;
 	int page, page_count;
+	u32 reloc_offset;
 
 	if (src == NULL)
 		return NULL;
@@ -442,18 +444,27 @@ i915_error_object_create(struct drm_device *dev,
 	if (dst == NULL)
 		return NULL;
 
+	reloc_offset = src_priv->gtt_offset;
 	for (page = 0; page < page_count; page++) {
-		void *s, *d = kmalloc(PAGE_SIZE, GFP_ATOMIC);
 		unsigned long flags;
+		void __iomem *s;
+		void *d;
 
+		d = kmalloc(PAGE_SIZE, GFP_ATOMIC);
 		if (d == NULL)
 			goto unwind;
+
 		local_irq_save(flags);
-		s = kmap_atomic(src_priv->pages[page], KM_IRQ0);
-		memcpy(d, s, PAGE_SIZE);
-		kunmap_atomic(s, KM_IRQ0);
+		s = io_mapping_map_atomic_wc(dev_priv->mm.gtt_mapping,
+					     reloc_offset,
+					     KM_IRQ0);
+		memcpy_fromio(d, s, PAGE_SIZE);
+		io_mapping_unmap_atomic(s, KM_IRQ0);
 		local_irq_restore(flags);
+
 		dst->pages[page] = d;
+
+		reloc_offset += PAGE_SIZE;
 	}
 	dst->page_count = page_count;
 	dst->gtt_offset = src_priv->gtt_offset;
@@ -613,18 +624,57 @@ static void i915_capture_error_state(struct drm_device *dev)
 
 		if (batchbuffer[1] == NULL &&
 		    error->acthd >= obj_priv->gtt_offset &&
-		    error->acthd < obj_priv->gtt_offset + obj->size &&
-		    batchbuffer[0] != obj)
+		    error->acthd < obj_priv->gtt_offset + obj->size)
 			batchbuffer[1] = obj;
 
 		count++;
 	}
+	/* Scan the other lists for completeness for those bizarre errors. */
+	if (batchbuffer[0] == NULL || batchbuffer[1] == NULL) {
+		list_for_each_entry(obj_priv, &dev_priv->mm.flushing_list, list) {
+			struct drm_gem_object *obj = &obj_priv->base;
+
+			if (batchbuffer[0] == NULL &&
+			    bbaddr >= obj_priv->gtt_offset &&
+			    bbaddr < obj_priv->gtt_offset + obj->size)
+				batchbuffer[0] = obj;
+
+			if (batchbuffer[1] == NULL &&
+			    error->acthd >= obj_priv->gtt_offset &&
+			    error->acthd < obj_priv->gtt_offset + obj->size)
+				batchbuffer[1] = obj;
+
+			if (batchbuffer[0] && batchbuffer[1])
+				break;
+		}
+	}
+	if (batchbuffer[0] == NULL || batchbuffer[1] == NULL) {
+		list_for_each_entry(obj_priv, &dev_priv->mm.inactive_list, list) {
+			struct drm_gem_object *obj = &obj_priv->base;
+
+			if (batchbuffer[0] == NULL &&
+			    bbaddr >= obj_priv->gtt_offset &&
+			    bbaddr < obj_priv->gtt_offset + obj->size)
+				batchbuffer[0] = obj;
+
+			if (batchbuffer[1] == NULL &&
+			    error->acthd >= obj_priv->gtt_offset &&
+			    error->acthd < obj_priv->gtt_offset + obj->size)
+				batchbuffer[1] = obj;
+
+			if (batchbuffer[0] && batchbuffer[1])
+				break;
+		}
+	}
 
 	/* We need to copy these to an anonymous buffer as the simplest
 	 * method to avoid being overwritten by userpace.
 	 */
 	error->batchbuffer[0] = i915_error_object_create(dev, batchbuffer[0]);
-	error->batchbuffer[1] = i915_error_object_create(dev, batchbuffer[1]);
+	if (batchbuffer[1] != batchbuffer[0])
+		error->batchbuffer[1] = i915_error_object_create(dev, batchbuffer[1]);
+	else
+		error->batchbuffer[1] = NULL;
 
 	/* Record the ringbuffer */
 	error->ringbuffer = i915_error_object_create(dev,