On Tue, Jun 04, 2019 at 02:18:19PM +0200, Andrey Konovalov wrote:
On Mon, Jun 3, 2019 at 7:46 PM Jason Gunthorpe jgg@ziepe.ca wrote:
On Mon, Jun 03, 2019 at 06:55:14PM +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.
ib_uverbs_(re)reg_mr() use provided user pointers for vma lookups (through e.g. mlx4_get_umem_mr()), which can only by done with untagged pointers.
Untag user pointers in these functions.
Signed-off-by: Andrey Konovalov andreyknvl@google.com drivers/infiniband/core/uverbs_cmd.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c index 5a3a1780ceea..f88ee733e617 100644 +++ b/drivers/infiniband/core/uverbs_cmd.c @@ -709,6 +709,8 @@ static int ib_uverbs_reg_mr(struct uverbs_attr_bundle *attrs) if (ret) return ret;
cmd.start = untagged_addr(cmd.start);if ((cmd.start & ~PAGE_MASK) != (cmd.hca_va & ~PAGE_MASK)) return -EINVAL;I feel like we shouldn't thave to do this here, surely the cmd.start should flow unmodified to get_user_pages, and gup should untag it?
ie, this sort of direction for the IB code (this would be a giant patch, so I didn't have time to write it all, but I think it is much saner):
Hi Jason,
ib_uverbs_reg_mr() passes cmd.start to mlx4_get_umem_mr(), which calls find_vma(), which only accepts untagged addresses. Could you explain how your patch helps?
That mlx4 is just a 'weird duck', it is not the normal flow, and I don't think the core code should be making special consideration for it.
Jason