On Fri, May 3, 2019 at 6:51 PM Catalin Marinas <catalin.marinas@xxxxxxx> wrote: > > On Tue, Apr 30, 2019 at 03:25:04PM +0200, 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. > > > > get_vaddr_frames uses provided user pointers for vma lookups, which can > > only by done with untagged pointers. Instead of locating and changing > > all callers of this function, perform untagging in it. > > > > Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> > > --- > > mm/frame_vector.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/mm/frame_vector.c b/mm/frame_vector.c > > index c64dca6e27c2..c431ca81dad5 100644 > > --- a/mm/frame_vector.c > > +++ b/mm/frame_vector.c > > @@ -46,6 +46,8 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, > > if (WARN_ON_ONCE(nr_frames > vec->nr_allocated)) > > nr_frames = vec->nr_allocated; > > > > + start = untagged_addr(start); > > + > > down_read(&mm->mmap_sem); > > locked = 1; > > vma = find_vma_intersection(mm, start, start + 1); > > Is this some buffer that the user may have malloc'ed? I got lost when > trying to track down the provenience of this buffer. The caller that I found when I was looking at this: drivers/gpu/drm/exynos/exynos_drm_g2d.c:482 exynos_g2d_set_cmdlist_ioctl()->g2d_map_cmdlist_gem()->g2d_userptr_get_dma_addr()->get_vaddr_frames() > > -- > Catalin
