On Fri, May 3, 2019 at 7:03 PM Catalin Marinas <catalin.marinas@xxxxxxx> wrote:
>
> On Tue, Apr 30, 2019 at 03:25:09PM +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.
> >
> > mlx4_get_umem_mr() 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@xxxxxxxxxx>
> > Reviewed-by: Leon Romanovsky <leonro@xxxxxxxxxxxx>
> > ---
> > drivers/infiniband/hw/mlx4/mr.c | 7 ++++---
> > 1 file changed, 4 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/infiniband/hw/mlx4/mr.c b/drivers/infiniband/hw/mlx4/mr.c
> > index 395379a480cb..9a35ed2c6a6f 100644
> > --- a/drivers/infiniband/hw/mlx4/mr.c
> > +++ b/drivers/infiniband/hw/mlx4/mr.c
> > @@ -378,6 +378,7 @@ static struct ib_umem *mlx4_get_umem_mr(struct ib_udata *udata, u64 start,
> > * again
> > */
> > if (!ib_access_writable(access_flags)) {
> > + unsigned long untagged_start = untagged_addr(start);
> > struct vm_area_struct *vma;
> >
> > down_read(¤t->mm->mmap_sem);
> > @@ -386,9 +387,9 @@ static struct ib_umem *mlx4_get_umem_mr(struct ib_udata *udata, u64 start,
> > * cover the memory, but for now it requires a single vma to
> > * entirely cover the MR to support RO mappings.
> > */
> > - vma = find_vma(current->mm, start);
> > - if (vma && vma->vm_end >= start + length &&
> > - vma->vm_start <= start) {
> > + vma = find_vma(current->mm, untagged_start);
> > + if (vma && vma->vm_end >= untagged_start + length &&
> > + vma->vm_start <= untagged_start) {
> > if (vma->vm_flags & VM_WRITE)
> > access_flags |= IB_ACCESS_LOCAL_WRITE;
> > } else {
>
> Discussion ongoing on the previous version of the patch but I'm more
> inclined to do this in ib_uverbs_(re)reg_mr() on cmd.start.
OK, I want to publish v15 sooner to fix the issue with emails
addresses, so I'll implement this approach there for now.
>
> --
> Catalin
