Re: [PATCH v13 15/20] drm/radeon, arm64: untag user pointers in radeon_ttm_tt_pin_userptr

Catalin Marinas
2019-03-22T16:00:57Z

On Wed, Mar 20, 2019 at 03:51:29PM +0100, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
>
> radeon_ttm_tt_pin_userptr() uses provided user pointers for vma
> lookups, which can only by done with untagged pointers.
>
> Untag user pointers in this function.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> ---
> drivers/gpu/drm/radeon/radeon_ttm.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c b/drivers/gpu/drm/radeon/radeon_ttm.c
> index 9920a6fc11bf..872a98796117 100644
> --- a/drivers/gpu/drm/radeon/radeon_ttm.c
> +++ b/drivers/gpu/drm/radeon/radeon_ttm.c
> @@ -497,9 +497,10 @@ static int radeon_ttm_tt_pin_userptr(struct ttm_tt *ttm)
> if (gtt->userflags & RADEON_GEM_USERPTR_ANONONLY) {
> /* check that we only pin down anonymous memory
> to prevent problems with writeback */
> - unsigned long end = gtt->userptr + ttm->num_pages * PAGE_SIZE;
> + unsigned long userptr = untagged_addr(gtt->userptr);
> + unsigned long end = userptr + ttm->num_pages * PAGE_SIZE;
> struct vm_area_struct *vma;
> - vma = find_vma(gtt->usermm, gtt->userptr);
> + vma = find_vma(gtt->usermm, userptr);
> if (!vma || vma->vm_file || vma->vm_end < end)
> return -EPERM;
> }

Same comment as on the previous patch.

--
Catalin