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

Andrey Konovalov
2019-04-02T14:17:52Z

On Fri, Mar 22, 2019 at 5:01 PM Catalin Marinas <catalin.marinas@arm.com> wrote:
>
> 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.

As Kevin wrote in the amd driver related thread, the call trace is:
radeon_gem_userptr_ioctl()->radeon_ttm_tt_set_userptr()->...->radeon_ttm_tt_pin_userptr()->find_vma()

>
> --
> Catalin