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Commit 09ac4fcb authored by Felix Kuehling's avatar Felix Kuehling Committed by Alex Deucher
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drm/ttm: Implement vm_operations_struct.access v2 



Allows gdb to access contents of user mode mapped BOs. System memory
is handled by TTM using kmap. Other memory pools require a new driver
callback in ttm_bo_driver.

v2:
* kmap only one page at a time
* swap in BO if needed
* make driver callback more generic to handle private memory pools
* document callback return value
* WARN_ON -> WARN_ON_ONCE

Signed-off-by: default avatarFelix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: default avatarChristian König <christian.koenig@amd.com>
Reviewed-by: default avatarMichel Dänzer <michel.daenzer@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent 16d6e962

drivers/gpu/drm/ttm/ttm_bo_vm.c

+78 −1
Original line number Diff line number Diff line
@@ -294,10 +294,87 @@ static void ttm_bo_vm_close(struct vm_area_struct *vma) 
	vma->vm_private_data = NULL;

}



static int ttm_bo_vm_access_kmap(struct ttm_buffer_object *bo,

				 unsigned long offset,

				 void *buf, int len, int write)

{

	unsigned long page = offset >> PAGE_SHIFT;

	unsigned long bytes_left = len;

	int ret;



	/* Copy a page at a time, that way no extra virtual address

	 * mapping is needed

	 */

	offset -= page << PAGE_SHIFT;

	do {

		unsigned long bytes = min(bytes_left, PAGE_SIZE - offset);

		struct ttm_bo_kmap_obj map;

		void *ptr;

		bool is_iomem;



		ret = ttm_bo_kmap(bo, page, 1, &map);

		if (ret)

			return ret;



		ptr = (uint8_t *)ttm_kmap_obj_virtual(&map, &is_iomem) + offset;

		WARN_ON_ONCE(is_iomem);

		if (write)

			memcpy(ptr, buf, bytes);

		else

			memcpy(buf, ptr, bytes);

		ttm_bo_kunmap(&map);



		page++;

		bytes_left -= bytes;

		offset = 0;

	} while (bytes_left);



	return len;

}



static int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,

			    void *buf, int len, int write)

{

	unsigned long offset = (addr) - vma->vm_start;

	struct ttm_buffer_object *bo = vma->vm_private_data;

	int ret;



	if (len < 1 || (offset + len) >> PAGE_SHIFT > bo->num_pages)

		return -EIO;



	ret = ttm_bo_reserve(bo, true, false, NULL);

	if (ret)

		return ret;



	switch (bo->mem.mem_type) {

	case TTM_PL_SYSTEM:

		if (unlikely(bo->ttm->page_flags & TTM_PAGE_FLAG_SWAPPED)) {

			ret = ttm_tt_swapin(bo->ttm);

			if (unlikely(ret != 0))

				return ret;

		}

		/* fall through */

	case TTM_PL_TT:

		ret = ttm_bo_vm_access_kmap(bo, offset, buf, len, write);

		break;

	default:

		if (bo->bdev->driver->access_memory)

			ret = bo->bdev->driver->access_memory(

				bo, offset, buf, len, write);

		else

			ret = -EIO;

	}



	ttm_bo_unreserve(bo);



	return ret;

}



static const struct vm_operations_struct ttm_bo_vm_ops = {

	.fault = ttm_bo_vm_fault,

	.open = ttm_bo_vm_open,

	.close = ttm_bo_vm_close

	.close = ttm_bo_vm_close,

	.access = ttm_bo_vm_access

};



static struct ttm_buffer_object *ttm_bo_vm_lookup(struct ttm_bo_device *bdev,

include/drm/ttm/ttm_bo_driver.h

+17 −0
Original line number Diff line number Diff line
@@ -472,6 +472,23 @@ struct ttm_bo_driver { 
	 */

	unsigned long (*io_mem_pfn)(struct ttm_buffer_object *bo,

				    unsigned long page_offset);



	/**

	 * Read/write memory buffers for ptrace access

	 *

	 * @bo: the BO to access

	 * @offset: the offset from the start of the BO

	 * @buf: pointer to source/destination buffer

	 * @len: number of bytes to copy

	 * @write: whether to read (0) from or write (non-0) to BO

	 *

	 * If successful, this function should return the number of

	 * bytes copied, -EIO otherwise. If the number of bytes

	 * returned is < len, the function may be called again with

	 * the remainder of the buffer to copy.

	 */

	int (*access_memory)(struct ttm_buffer_object *bo, unsigned long offset,

			     void *buf, int len, int write);

};



/**