1 files changed, 43 insertions, 14 deletions

diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index b6abc852f2a1..78f52488f9ff 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -17,22 +17,51 @@
 
 #include <asm/efi.h>
 
-int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md)
+/*
+ * Only regions of type EFI_RUNTIME_SERVICES_CODE need to be
+ * executable, everything else can be mapped with the XN bits
+ * set. Also take the new (optional) RO/XP bits into account.
+ */
+static __init pteval_t create_mapping_protection(efi_memory_desc_t *md)
 {
-        pteval_t prot_val;
+        u64 attr = md->attribute;
+        u32 type = md->type;
 
-        /*
-         * Only regions of type EFI_RUNTIME_SERVICES_CODE need to be
-         * executable, everything else can be mapped with the XN bits
-         * set.
-         */
-        if ((md->attribute & EFI_MEMORY_WB) == 0)
-                prot_val = PROT_DEVICE_nGnRE;
-        else if (md->type == EFI_RUNTIME_SERVICES_CODE ||
-                 !PAGE_ALIGNED(md->phys_addr))
-                prot_val = pgprot_val(PAGE_KERNEL_EXEC);
-        else
-                prot_val = pgprot_val(PAGE_KERNEL);
+        if (type == EFI_MEMORY_MAPPED_IO)
+                return PROT_DEVICE_nGnRE;
+
+        if (WARN_ONCE(!PAGE_ALIGNED(md->phys_addr),
+                      "UEFI Runtime regions are not aligned to 64 KB -- buggy firmware?"))
+                /*
+                 * If the region is not aligned to the page size of the OS, we
+                 * can not use strict permissions, since that would also affect
+                 * the mapping attributes of the adjacent regions.
+                 */
+                return pgprot_val(PAGE_KERNEL_EXEC);
+
+        /* R-- */
+        if ((attr & (EFI_MEMORY_XP | EFI_MEMORY_RO)) ==
+            (EFI_MEMORY_XP | EFI_MEMORY_RO))
+                return pgprot_val(PAGE_KERNEL_RO);
+
+        /* R-X */
+        if (attr & EFI_MEMORY_RO)
+                return pgprot_val(PAGE_KERNEL_ROX);
+
+        /* RW- */
+        if (attr & EFI_MEMORY_XP || type != EFI_RUNTIME_SERVICES_CODE)
+                return pgprot_val(PAGE_KERNEL);
+
+        /* RWX */
+        return pgprot_val(PAGE_KERNEL_EXEC);
+}
+
+/* we will fill this structure from the stub, so don't put it in .bss */
+struct screen_info screen_info __section(.data);
+
+int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md)
+{
+        pteval_t prot_val = create_mapping_protection(md);
 
         create_pgd_mapping(mm, md->phys_addr, md->virt_addr,
                            md->num_pages << EFI_PAGE_SHIFT,