msm: iommu: re-use existing buffers for `extra' mappings
There is a bug on some hardware that requires us to overmap Iommu
mappings by 2x. Currently, we set aside a dummy buffer onto which we
map all of these dummy mappings. In general, for large mappings it's
nice to use the more efficient iommu_map_range instead of calling
iommu_map repeatedly. However, with our current approach in
msm_iommu_map_extra we can't use iommu_map_range for page_sizes larger
than the dummy buffer. To avoid wasting memory by increasing the size
of the dummy buffer, we can simply remap on top of the the buffer
being mapped in the first place. Since the second mapping should never
be used (besides by the buggy hardware) this should not be a problem.

Re-use existing buffers for all `extra' mappings. Essentially, map the
same physical address range twice. To be extra safe, make the second
mapping read-only.

Change-Id: I35462ad50de8da1f2befa3e3f0895925535cdc98
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>
msm: Fix race condition in domain lookup

During lookup of domains we take a pointer to the root node
of the rb tree before taking the mutex to protect the rb tree.
However, the rb root node might change if another process updates
the rb tree after we take the pointer to the root node. This can
cause us to not find the entry that we are looking for.
Fix this by ensuring we have taken the mutex before getting the
root node pointer.

CRs-fixed: 493503
Change-Id: I4702740e486fda0cd92df0401d8e4706598a899b
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
gpu: ion: remove stale variable

Tracking the number of user mappings should be done in the Ion
heaps. Remove the variable that was used to track this in core Ion.

Change-Id: I715280515e3010bd002314aefe0ec8cdb37c143d
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>
gpu: ion: Remove get_flags ioctl

There are no callers of the get flags ioctl. Remove it
before anyone tries to use it again.

Change-Id: I857ef705fc864cce49f671124b96bd9f47b66ab2
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>