Re: [PATCH v14 13/17] IB/mlx4, arm64: untag user pointers in mlx4_get_umem_mr

On Fri, May 3, 2019 at 7:03 PM Catalin Marinas catalin.marinas@arm.com 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@google.com Reviewed-by: Leon Romanovsky leonro@mellanox.com

---

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(&current->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