On 17-07-13 11:26 PM, Michel Dänzer wrote:
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?
Maybe. I'm not really familiar with ttm_bo_kmap limitations on 32-bit. I guess the the access would have to be really big. I think in practice GDB doesn't do very big accesses. So I'm not sure it's worth the trouble.
- 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 accessIs 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.
Good point. I'll change that.
* @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.
I made this as similar as possible to the vm_ops->access API, where write is also an integer.
Regards, Felix