[U-Boot] [PATCH v2] efi_loader: Align runtime section to 64kb

[Alexander Graf]

The UEFI spec mandates that runtime sections are 64kb aligned to enable
support for 64kb page size OSs.

This patch ensures that we extend the runtime section to 64kb to be spec
compliant.

Signed-off-by: Alexander Graf <agraf at suse.de>

---

v1 -> v2:

  - rename kb to KiB in accordance to the spec
  - add reference to spec section for alignment requirement
  - only use 64KiB alignment on aarch64
---
 lib/efi_loader/efi_memory.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/lib/efi_loader/efi_memory.c b/lib/efi_loader/efi_memory.c
index 5bd4f4d7fc..b4cb543275 100644
--- a/lib/efi_loader/efi_memory.c
+++ b/lib/efi_loader/efi_memory.c
@@ -11,6 +11,7 @@
 #include <mapmem.h>
 #include <watchdog.h>
 #include <linux/list_sort.h>
+#include <linux/sizes.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -563,6 +564,7 @@ __weak void efi_add_known_memory(void)
 static void add_u_boot_and_runtime(void)
 {
 	unsigned long runtime_start, runtime_end, runtime_pages;
+	unsigned long runtime_mask = EFI_PAGE_MASK;
 	unsigned long uboot_start, uboot_pages;
 	unsigned long uboot_stack_size = 16 * 1024 * 1024;
 
@@ -571,10 +573,22 @@ static void add_u_boot_and_runtime(void)
 	uboot_pages = (gd->ram_top - uboot_start) >> EFI_PAGE_SHIFT;
 	efi_add_memory_map(uboot_start, uboot_pages, EFI_LOADER_DATA, false);
 
-	/* Add Runtime Services */
-	runtime_start = (ulong)&__efi_runtime_start & ~EFI_PAGE_MASK;
+#if defined(__aarch64__)
+	/*
+	 * Runtime Services must be 64KiB aligned according to the
+	 * "AArch64 Platforms" section in the UEFI spec (2.7+).
+	 */
+
+	runtime_mask = SZ_64K - 1;
+#endif
+
+	/*
+	 * Add Runtime Services. We mark surrounding boottime code as runtime as
+	 * well to fulfill the runtime alignment constraints but avoid padding.
+	 */
+	runtime_start = (ulong)&__efi_runtime_start & ~runtime_mask;
 	runtime_end = (ulong)&__efi_runtime_stop;
-	runtime_end = (runtime_end + EFI_PAGE_MASK) & ~EFI_PAGE_MASK;
+	runtime_end = (runtime_end + runtime_mask) & ~runtime_mask;
 	runtime_pages = (runtime_end - runtime_start) >> EFI_PAGE_SHIFT;
 	efi_add_memory_map(runtime_start, runtime_pages,
 			   EFI_RUNTIME_SERVICES_CODE, false);
-- 
2.12.3