[GIT PULL] EFI fixes

[Ingo Molnar <mingo@kernel.org>]

Linus,

Please pull the latest core-urgent-for-linus git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git core-urgent-for-linus

   # HEAD: 0ce3cc008ec04258b6a6314b09f1a6012810881a arm64/efi: Fix boot crash by not padding between EFI_MEMORY_RUNTIME regions

Two EFI fixes: one for x86, one for ARM, fixing a boot crash bug that can trigger 
under newer EFI firmware.

 Thanks,

	Ingo

------------------>
Ard Biesheuvel (1):
      arm64/efi: Fix boot crash by not padding between EFI_MEMORY_RUNTIME regions

Matt Fleming (1):
      x86/efi: Fix boot crash by mapping EFI memmap entries bottom-up at runtime, instead of top-down


 arch/arm64/kernel/efi.c                 |  3 +-
 arch/x86/platform/efi/efi.c             | 67 ++++++++++++++++++++++++-
 drivers/firmware/efi/libstub/arm-stub.c | 88 +++++++++++++++++++++++++++------
 3 files changed, 141 insertions(+), 17 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 @@ static void *realloc_pages(void *old_memmap, int old_shift)
 }
 
 /*
+ * 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
diff --git a/drivers/firmware/efi/libstub/arm-stub.c b/drivers/firmware/efi/libstub/arm-stub.c
index e29560e6b40b..950c87f5d279 100644
--- a/drivers/firmware/efi/libstub/arm-stub.c
+++ b/drivers/firmware/efi/libstub/arm-stub.c
@@ -13,6 +13,7 @@
  */
 
 #include <linux/efi.h>
+#include <linux/sort.h>
 #include <asm/efi.h>
 
 #include "efistub.h"
@@ -305,6 +306,44 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
  */
 #define EFI_RT_VIRTUAL_BASE	0x40000000
 
+static int cmp_mem_desc(const void *l, const void *r)
+{
+	const efi_memory_desc_t *left = l, *right = r;
+
+	return (left->phys_addr > right->phys_addr) ? 1 : -1;
+}
+
+/*
+ * Returns whether region @left ends exactly where region @right starts,
+ * or false if either argument is NULL.
+ */
+static bool regions_are_adjacent(efi_memory_desc_t *left,
+				 efi_memory_desc_t *right)
+{
+	u64 left_end;
+
+	if (left == NULL || right == NULL)
+		return false;
+
+	left_end = left->phys_addr + left->num_pages * EFI_PAGE_SIZE;
+
+	return left_end == right->phys_addr;
+}
+
+/*
+ * Returns whether region @left and region @right have compatible memory type
+ * mapping attributes, and are both EFI_MEMORY_RUNTIME regions.
+ */
+static bool regions_have_compatible_memory_type_attrs(efi_memory_desc_t *left,
+						      efi_memory_desc_t *right)
+{
+	static const u64 mem_type_mask = EFI_MEMORY_WB | EFI_MEMORY_WT |
+					 EFI_MEMORY_WC | EFI_MEMORY_UC |
+					 EFI_MEMORY_RUNTIME;
+
+	return ((left->attribute ^ right->attribute) & mem_type_mask) == 0;
+}
+
 /*
  * efi_get_virtmap() - create a virtual mapping for the EFI memory map
  *
@@ -317,33 +356,52 @@ void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
 		     int *count)
 {
 	u64 efi_virt_base = EFI_RT_VIRTUAL_BASE;
-	efi_memory_desc_t *out = runtime_map;
+	efi_memory_desc_t *in, *prev = NULL, *out = runtime_map;
 	int l;
 
-	for (l = 0; l < map_size; l += desc_size) {
-		efi_memory_desc_t *in = (void *)memory_map + l;
+	/*
+	 * To work around potential issues with the Properties Table feature
+	 * introduced in UEFI 2.5, which may split PE/COFF executable images
+	 * in memory into several RuntimeServicesCode and RuntimeServicesData
+	 * regions, we need to preserve the relative offsets between adjacent
+	 * EFI_MEMORY_RUNTIME regions with the same memory type attributes.
+	 * The easiest way to find adjacent regions is to sort the memory map
+	 * before traversing it.
+	 */
+	sort(memory_map, map_size / desc_size, desc_size, cmp_mem_desc, NULL);
+
+	for (l = 0; l < map_size; l += desc_size, prev = in) {
 		u64 paddr, size;
 
+		in = (void *)memory_map + l;
 		if (!(in->attribute & EFI_MEMORY_RUNTIME))
 			continue;
 
+		paddr = in->phys_addr;
+		size = in->num_pages * EFI_PAGE_SIZE;
+
 		/*
 		 * Make the mapping compatible with 64k pages: this allows
 		 * a 4k page size kernel to kexec a 64k page size kernel and
 		 * vice versa.
 		 */
-		paddr = round_down(in->phys_addr, SZ_64K);
-		size = round_up(in->num_pages * EFI_PAGE_SIZE +
-				in->phys_addr - paddr, SZ_64K);
-
-		/*
-		 * Avoid wasting memory on PTEs by choosing a virtual base that
-		 * is compatible with section mappings if this region has the
-		 * appropriate size and physical alignment. (Sections are 2 MB
-		 * on 4k granule kernels)
-		 */
-		if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
-			efi_virt_base = round_up(efi_virt_base, SZ_2M);
+		if (!regions_are_adjacent(prev, in) ||
+		    !regions_have_compatible_memory_type_attrs(prev, in)) {
+
+			paddr = round_down(in->phys_addr, SZ_64K);
+			size += in->phys_addr - paddr;
+
+			/*
+			 * Avoid wasting memory on PTEs by choosing a virtual
+			 * base that is compatible with section mappings if this
+			 * region has the appropriate size and physical
+			 * alignment. (Sections are 2 MB on 4k granule kernels)
+			 */
+			if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
+				efi_virt_base = round_up(efi_virt_base, SZ_2M);
+			else
+				efi_virt_base = round_up(efi_virt_base, SZ_64K);
+		}
 
 		in->virt_addr = efi_virt_base + in->phys_addr - paddr;
 		efi_virt_base += size;