gpu: ion: Refactor the code to zero buffers

Refactor the code in the system heap used to map and zero the buffers
into a seperate utility so it can be called from other heaps.  Use it from
the chunk heap.
Signed-off-by: Rebecca Schultz Zavin <rebecca@android.com>
[jstultz: modified patch to apply to staging directory]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/android/ion/ion_chunk_heap.c

@@ -101,6 +101,8 @@ static void ion_chunk_heap_free(struct ion_buffer *buffer)
 	struct scatterlist *sg;
 	int i;
 
+	ion_heap_buffer_zero(buffer);
+
 	for_each_sg(table->sgl, sg, table->nents, i) {
 		__dma_page_cpu_to_dev(sg_page(sg), 0, sg_dma_len(sg),
 				      DMA_BIDIRECTIONAL);

drivers/staging/android/ion/ion_heap.c

@@ -93,6 +93,43 @@ int ion_heap_map_user(struct ion_heap *heap, struct ion_buffer *buffer,
 	return 0;
 }
 
+int ion_heap_buffer_zero(struct ion_buffer *buffer)
+{
+	struct sg_table *table = buffer->sg_table;
+	pgprot_t pgprot;
+	struct scatterlist *sg;
+	struct vm_struct *vm_struct;
+	int i, j, ret = 0;
+
+	if (buffer->flags & ION_FLAG_CACHED)
+		pgprot = PAGE_KERNEL;
+	else
+		pgprot = pgprot_writecombine(PAGE_KERNEL);
+
+	vm_struct = get_vm_area(PAGE_SIZE, VM_ALLOC);
+	if (!vm_struct)
+		return -ENOMEM;
+
+	for_each_sg(table->sgl, sg, table->nents, i) {
+		struct page *page = sg_page(sg);
+		unsigned long len = sg_dma_len(sg);
+
+		for (j = 0; j < len / PAGE_SIZE; j++) {
+			struct page *sub_page = page + j;
+			struct page **pages = &sub_page;
+			ret = map_vm_area(vm_struct, pgprot, &pages);
+			if (ret)
+				goto end;
+			memset(vm_struct->addr, 0, PAGE_SIZE);
+			unmap_kernel_range((unsigned long)vm_struct->addr,
+					   PAGE_SIZE);
+		}
+	}
+end:
+	free_vm_area(vm_struct);
+	return ret;
+}
+
 struct ion_heap *ion_heap_create(struct ion_platform_heap *heap_data)
 {
 	struct ion_heap *heap = NULL;

drivers/staging/android/ion/ion_priv.h

@@ -185,6 +185,7 @@ void *ion_heap_map_kernel(struct ion_heap *, struct ion_buffer *);
 void ion_heap_unmap_kernel(struct ion_heap *, struct ion_buffer *);
 int ion_heap_map_user(struct ion_heap *, struct ion_buffer *,
 			struct vm_area_struct *);
+int ion_heap_buffer_zero(struct ion_buffer *buffer);
 
 
 /**

drivers/staging/android/ion/ion_system_heap.c

@@ -91,7 +91,7 @@ static struct page *alloc_buffer_page(struct ion_system_heap *heap,
 
 static void free_buffer_page(struct ion_system_heap *heap,
 			     struct ion_buffer *buffer, struct page *page,
-			     unsigned int order, struct vm_struct *vm_struct)
+			     unsigned int order)
 {
 	bool cached = ion_buffer_cached(buffer);
 	bool split_pages = ion_buffer_fault_user_mappings(buffer);
@@ -99,20 +99,6 @@ static void free_buffer_page(struct ion_system_heap *heap,
 
 	if (!cached) {
 		struct ion_page_pool *pool = heap->pools[order_to_index(order)];
-		/* zero the pages before returning them to the pool for
-		   security.  This uses vmap as we want to set the pgprot so
-		   the writes to occur to noncached mappings, as the pool's
-		   purpose is to keep the pages out of the cache */
-		for (i = 0; i < (1 << order); i++) {
-			struct page *sub_page = page + i;
-			struct page **pages = &sub_page;
-			map_vm_area(vm_struct,
-					 pgprot_writecombine(PAGE_KERNEL),
-					 &pages);
-			memset(vm_struct->addr, 0, PAGE_SIZE);
-			unmap_kernel_range((unsigned long)vm_struct->addr,
-					PAGE_SIZE);
-		}
 		ion_page_pool_free(pool, page);
 	} else if (split_pages) {
 		for (i = 0; i < (1 << order); i++)
@@ -167,8 +153,6 @@ static int ion_system_heap_allocate(struct ion_heap *heap,
 	long size_remaining = PAGE_ALIGN(size);
 	unsigned int max_order = orders[0];
 	bool split_pages = ion_buffer_fault_user_mappings(buffer);
-	struct vm_struct *vm_struct;
-	pte_t *ptes;
 
 	INIT_LIST_HEAD(&pages);
 	while (size_remaining > 0) {
@@ -216,13 +200,10 @@ static int ion_system_heap_allocate(struct ion_heap *heap,
 err1:
 	kfree(table);
 err:
-	vm_struct = get_vm_area(PAGE_SIZE, &ptes);
 	list_for_each_entry(info, &pages, list) {
-		free_buffer_page(sys_heap, buffer, info->page, info->order,
-				vm_struct);
+		free_buffer_page(sys_heap, buffer, info->page, info->order);
 		kfree(info);
 	}
-	free_vm_area(vm_struct);
 	return -ENOMEM;
 }
 
@@ -233,18 +214,19 @@ void ion_system_heap_free(struct ion_buffer *buffer)
 							struct ion_system_heap,
 							heap);
 	struct sg_table *table = buffer->sg_table;
+	bool cached = ion_buffer_cached(buffer);
 	struct scatterlist *sg;
 	LIST_HEAD(pages);
-	struct vm_struct *vm_struct;
-	pte_t *ptes;
 	int i;
 
-	vm_struct = get_vm_area(PAGE_SIZE, &ptes);
+	/* uncached pages come from the page pools, zero them before returning
+	   for security purposes (other allocations are zerod at alloc time */
+	if (!cached)
+		ion_heap_buffer_zero(buffer);
 
 	for_each_sg(table->sgl, sg, table->nents, i)
 		free_buffer_page(sys_heap, buffer, sg_page(sg),
-				get_order(sg_dma_len(sg)), vm_struct);
-	free_vm_area(vm_struct);
+				get_order(sg_dma_len(sg)));
 	sg_free_table(table);
 	kfree(table);
 }