On 14/07/17 06:08 AM, Felix Kuehling wrote:
> Allows gdb to access contents of user mode mapped BOs. VRAM access
> requires the driver to implement a new callback in ttm_bo_driver.
Thanks for doing this. Looks mostly good, but I still have some comments.
The shortlog prefix should be "drm/ttm:".
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> index 9f53df9..0ef2eb9 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> @@ -294,10 +294,74 @@ 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 first_page = offset >> PAGE_SHIFT;
> + unsigned long last_page = (offset + len - 1) >> PAGE_SHIFT;
> + unsigned long num_pages = last_page - first_page + 1;
> + struct ttm_bo_kmap_obj map;
> + void *ptr;
> + bool is_iomem;
> + int ret;
> +
> + ret = ttm_bo_kmap(bo, first_page, num_pages, &map);
> + if (ret)
> + return ret;
Could there be cases (e.g. on 32-bit) where mapping all pages at once
fails, but mapping one page at a time would work?
> + offset -= first_page << PAGE_SHIFT;
> + ptr = (uint8_t *)ttm_kmap_obj_virtual(&map, &is_iomem) + offset;
> + WARN_ON(is_iomem);
I suggest making this WARN_ON_ONCE, to avoid flooding dmesg if it ever
triggers in practice.
> static struct ttm_buffer_object *ttm_bo_vm_lookup(struct ttm_bo_device *bdev,
> diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
> index 6bbd34d..6ce5094 100644
> --- a/include/drm/ttm/ttm_bo_driver.h
> +++ b/include/drm/ttm/ttm_bo_driver.h
> @@ -471,6 +471,18 @@ struct ttm_bo_driver {
> */
> unsigned long (*io_mem_pfn)(struct ttm_buffer_object *bo,
> unsigned long page_offset);
> +
> + /**
> + * Read/write VRAM buffers for ptrace access
Is there any reason for making this specific to VRAM? ttm_bo_vm_access
could just call this for anything except TTM_PL_SYSTEM / TTM_PL_TT, and
let the driver return an error if it can't handle the memory type.
> + * @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
> + */
The meaning of the return value should also be documented here.
> + int (*access_vram)(struct ttm_buffer_object *bo, unsigned long offset,
> + void *buf, int len, int write);
> };
I suggest making the write parameter a bool.
--
Earthling Michel Dänzer | http://www.amd.com
Libre software enthusiast | Mesa and X developer
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