1 files changed, 41 insertions, 0 deletions

diff --git a/arch/arm/kernel/efi.c b/arch/arm/kernel/efi.c
index ff8a9d8acfac..9f43ba012d10 100644
--- a/arch/arm/kernel/efi.c
+++ b/arch/arm/kernel/efi.c
@@ -11,6 +11,41 @@
 #include <asm/mach/map.h>
 #include <asm/mmu_context.h>
 
+static int __init set_permissions(pte_t *ptep, pgtable_t token,
+                                  unsigned long addr, void *data)
+{
+        efi_memory_desc_t *md = data;
+        pte_t pte = *ptep;
+
+        if (md->attribute & EFI_MEMORY_RO)
+                pte = set_pte_bit(pte, __pgprot(L_PTE_RDONLY));
+        if (md->attribute & EFI_MEMORY_XP)
+                pte = set_pte_bit(pte, __pgprot(L_PTE_XN));
+        set_pte_ext(ptep, pte, PTE_EXT_NG);
+        return 0;
+}
+
+int __init efi_set_mapping_permissions(struct mm_struct *mm,
+                                       efi_memory_desc_t *md)
+{
+        unsigned long base, size;
+
+        base = md->virt_addr;
+        size = md->num_pages << EFI_PAGE_SHIFT;
+
+        /*
+         * We can only use apply_to_page_range() if we can guarantee that the
+         * entire region was mapped using pages. This should be the case if the
+         * region does not cover any naturally aligned SECTION_SIZE sized
+         * blocks.
+         */
+        if (round_down(base + size, SECTION_SIZE) <
+            round_up(base, SECTION_SIZE) + SECTION_SIZE)
+                return apply_to_page_range(mm, base, size, set_permissions, md);
+
+        return 0;
+}
+
 int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md)
 {
         struct map_desc desc = {
@@ -34,5 +69,11 @@ int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md)
                 desc.type = MT_DEVICE;
 
         create_mapping_late(mm, &desc, true);
+
+        /*
+         * If stricter permissions were specified, apply them now.
+         */
+        if (md->attribute & (EFI_MEMORY_RO | EFI_MEMORY_XP))
+                return efi_set_mapping_permissions(mm, md);
         return 0;
 }