drm: add flag for mapping PCI DMA buffers read-only.
Add DRM_PCI_BUFFER_RO flag for mapping PCI DMA buffer read-only. An additional
flag is needed, since PCI DMA buffers do not have an associated map.
Signed-off-by: Dave Airlie <airlied@linux.ie>
diff --git a/drivers/char/drm/drm_vm.c b/drivers/char/drm/drm_vm.c
index b40ae43..74686e9 100644
--- a/drivers/char/drm/drm_vm.c
+++ b/drivers/char/drm/drm_vm.c
@@ -473,6 +473,22 @@
}
unlock_kernel();
+ if (!capable(CAP_SYS_ADMIN) &&
+ (dma->flags & _DRM_DMA_USE_PCI_RO)) {
+ vma->vm_flags &= ~(VM_WRITE | VM_MAYWRITE);
+#if defined(__i386__) || defined(__x86_64__)
+ pgprot_val(vma->vm_page_prot) &= ~_PAGE_RW;
+#else
+ /* Ye gads this is ugly. With more thought
+ we could move this up higher and use
+ `protection_map' instead. */
+ vma->vm_page_prot =
+ __pgprot(pte_val
+ (pte_wrprotect
+ (__pte(pgprot_val(vma->vm_page_prot)))));
+#endif
+ }
+
vma->vm_ops = &drm_vm_dma_ops;
vma->vm_flags |= VM_RESERVED; /* Don't swap */