gpu: ion: exynos: fix map_dma() for EXYNOS_CONTIG heap

sg_init_one() expects a virtual address

Change-Id: I2f95c99c090666ec65aea0cdf2a389d8642c6533
Signed-off-by: Greg Hackmann <ghackmann@google.com>
gpu: ion: Use alloc_pages instead of vmalloc from the system heap

With this change the ion_system_heap will only use kernel address
space when the memory is mapped into the kernel (rare case).

Change-Id: I8702cf89ffec0bd5c337bd88d7444013d4d94bc8
Signed-off-by: Rebecca Schultz Zavin <rebecca@android.com>
gpu: ion: ion_system_heap: Change allocations to GFP_HIGHUSER

Previously the ion_system_heap was using GFP_KERNEL, forcing all allocations
to be in lowmem.  This quickly causes us to run out of lowmem.

Change-Id: I6d502a5f1c20c8a8e44fb5903fcb228f8435a564
Signed-off-by: Rebecca Schultz Zavin <rebecca@android.com>
gpu: ion: Map only the vma size given

When mapping carveout buffers into userspace, only map
the size of the vma given, not the full size of the buffer
since clients may map less than the buffer size.

Change-Id: I1b391b23219455e879a900d947c728db3c8c4a76
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>