video: tegra: nvmap: deal with read vs write fault

This change modifies the user fault handler to
- allow read access on reserved page
- do not mark pages which are read by cpu as dirty

Bug 1444151
Bug 1444298

Change-Id: Ic0550503fe27ecd179e9d24f09cc344613249be5
Signed-off-by: Sri Krishna chowdary <schowdary@nvidia.com>
Reviewed-on: http://git-master/r/403969
(cherry picked from commit d8c2a9f56bbfbb90d90719a8fcae58e1b6f0df3c)
Reviewed-on: http://git-master/r/405155
GVS: Gerrit_Virtual_Submit
Reviewed-by: Bharat Nihalani <bnihalani@nvidia.com>

diff --git a/drivers/video/tegra/nvmap/nvmap_dev.c b/drivers/video/tegra/nvmap/nvmap_dev.c
index 30ceb31291e9692c2074261237cd028316af30a7..b1a4a702ca41f926217adc7114c9d006178f7b14 100644 (file)
--- a/drivers/video/tegra/nvmap/nvmap_dev.c
+++ b/drivers/video/tegra/nvmap/nvmap_dev.c
@@ -831,10 +831,12 @@ static int nvmap_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
                page = pfn_to_page(pfn);
        } else {
                offs >>= PAGE_SHIFT;
-               if (nvmap_page_reserved(priv->handle->pgalloc.pages[offs]))
-                       return VM_FAULT_SIGBUS;
+               if (vmf->flags & (FAULT_FLAG_WRITE | FAULT_FLAG_MKWRITE)) {
+                       if (nvmap_page_reserved(priv->handle->pgalloc.pages[offs]))
+                               return VM_FAULT_SIGBUS;
+                       nvmap_page_mkdirty(&priv->handle->pgalloc.pages[offs]);
+               }
                page = nvmap_to_page(priv->handle->pgalloc.pages[offs]);
-               nvmap_page_mkdirty(&priv->handle->pgalloc.pages[offs]);
        }
 
        if (page)