iommu/tegra-smmu: Fix unmap() method

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The Tegra SMMU unmap path has several problems:
1. as_pte_put() can perform a write-after-free
2. tegra_smmu_unmap() can perform cache maintanence on a page we have
   just freed.
3. when a page table is unmapped, there is no CPU cache maintanence of
   the write clearing the page directory entry, nor is there any
   maintanence of the IOMMU to ensure that it sees the page table has
   gone.

Fix this by getting rid of as_pte_put(), and instead coding the PTE
unmap separately from the PDE unmap, placing the PDE unmap after the
PTE unmap has been completed.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Thierry Reding <treding@nvidia.com>

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Russell King 2015-07-27 13:29:05 +01:00 • committed by Thierry Reding

parent 9113785c3e

commit b98e34f0c6

1 changed files with 23 additions and 14 deletions

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drivers/iommu/tegra-smmu.c

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