Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull EFI fixes from Ingo Molnar:
 "Two EFI fixes: one for x86, one for ARM, fixing a boot crash bug that
  can trigger under newer EFI firmware"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  arm64/efi: Fix boot crash by not padding between EFI_MEMORY_RUNTIME regions
  x86/efi: Fix boot crash by mapping EFI memmap entries bottom-up at runtime, instead of top-down

2 files changed, 68 insertions, 2 deletions

diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index e8ca6eaedd02..13671a9cf016 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -258,7 +258,8 @@ static bool __init efi_virtmap_init(void)
                  */
                 if (!is_normal_ram(md))
                         prot = __pgprot(PROT_DEVICE_nGnRE);
-                else if (md->type == EFI_RUNTIME_SERVICES_CODE)
+                else if (md->type == EFI_RUNTIME_SERVICES_CODE ||
+                         !PAGE_ALIGNED(md->phys_addr))
                         prot = PAGE_KERNEL_EXEC;
                 else
                         prot = PAGE_KERNEL;
diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 1db84c0758b7..6a28ded74211 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -705,6 +705,70 @@ out:
 }
 
 /*
+ * Iterate the EFI memory map in reverse order because the regions
+ * will be mapped top-down. The end result is the same as if we had
+ * mapped things forward, but doesn't require us to change the
+ * existing implementation of efi_map_region().
+ */
+static inline void *efi_map_next_entry_reverse(void *entry)
+{
+        /* Initial call */
+        if (!entry)
+                return memmap.map_end - memmap.desc_size;
+
+        entry -= memmap.desc_size;
+        if (entry < memmap.map)
+                return NULL;
+
+        return entry;
+}
+
+/*
+ * efi_map_next_entry - Return the next EFI memory map descriptor
+ * @entry: Previous EFI memory map descriptor
+ *
+ * This is a helper function to iterate over the EFI memory map, which
+ * we do in different orders depending on the current configuration.
+ *
+ * To begin traversing the memory map @entry must be %NULL.
+ *
+ * Returns %NULL when we reach the end of the memory map.
+ */
+static void *efi_map_next_entry(void *entry)
+{
+        if (!efi_enabled(EFI_OLD_MEMMAP) && efi_enabled(EFI_64BIT)) {
+                /*
+                 * Starting in UEFI v2.5 the EFI_PROPERTIES_TABLE
+                 * config table feature requires us to map all entries
+                 * in the same order as they appear in the EFI memory
+                 * map. That is to say, entry N must have a lower
+                 * virtual address than entry N+1. This is because the
+                 * firmware toolchain leaves relative references in
+                 * the code/data sections, which are split and become
+                 * separate EFI memory regions. Mapping things
+                 * out-of-order leads to the firmware accessing
+                 * unmapped addresses.
+                 *
+                 * Since we need to map things this way whether or not
+                 * the kernel actually makes use of
+                 * EFI_PROPERTIES_TABLE, let's just switch to this
+                 * scheme by default for 64-bit.
+                 */
+                return efi_map_next_entry_reverse(entry);
+        }
+
+        /* Initial call */
+        if (!entry)
+                return memmap.map;
+
+        entry += memmap.desc_size;
+        if (entry >= memmap.map_end)
+                return NULL;
+
+        return entry;
+}
+
+/*
  * Map the efi memory ranges of the runtime services and update new_mmap with
  * virtual addresses.
  */
@@ -714,7 +778,8 @@ static void * __init efi_map_regions(int *count, int *pg_shift)
         unsigned long left = 0;
         efi_memory_desc_t *md;
 
-        for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
+        p = NULL;
+        while ((p = efi_map_next_entry(p))) {
                 md = p;
                 if (!(md->attribute & EFI_MEMORY_RUNTIME)) {
 #ifdef CONFIG_X86_64