[PATCH review for 4.4 42/47] iommu/io-pgtable-arm: Check for leaf entry before dereferencing it

From: Oleksandr Tyshchenko [ Upstream commit ed46e66cc1b3d684042f92dfa2ab15ee917b4cac ] Do a check for already installed leaf entry at the current level before dereferencing it in order to avoid walking the page table down with wrong pointer to the next level.

[PATCH review for 4.4 42/47] iommu/io-pgtable-arm: Check for leaf entry before dereferencing it

From: Oleksandr Tyshchenko [ Upstream commit ed46e66cc1b3d684042f92dfa2ab15ee917b4cac ] Do a check for already installed leaf entry at the current level before dereferencing it in order to avoid walking the page table down with wrong pointer to the next level. Signed-off-by: Oleksandr