efi: Add 64-bit payload support

Most EFI implementations use 64-bit. Add a way to build U-Boot as a 64-bit
EFI payload. The payload unpacks a (32-bit) U-Boot and starts it. This can
be enabled for x86 boards at present.

Signed-off-by: Simon Glass <sjg@chromium.org>
Improvements to how the payload is built:
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>

arch/x86/config.mk

@@ -34,14 +34,24 @@ OBJCOPYFLAGS_EFI := -j .text -j .sdata -j .data -j .dynamic -j .dynsym \
 CFLAGS_NON_EFI := -mregparm=3
 CFLAGS_EFI := -fpic -fshort-wchar
 
+ifeq ($(CONFIG_EFI_STUB_64BIT),)
+CFLAGS_EFI += $(call cc-option, -mno-red-zone)
 EFIARCH = ia32
 EFIPAYLOAD_BFDTARGET = elf32-i386
+else
+EFIARCH = x86_64
+EFIPAYLOAD_BFDTARGET = elf64-x86-64
+endif
 
 EFIPAYLOAD_BFDARCH = i386
 
 LDSCRIPT_EFI := $(srctree)/$(CPUDIR)/efi/elf_$(EFIARCH)_efi.lds
+EFISTUB := crt0-efi-$(EFIARCH).o reloc_$(EFIARCH).o
 OBJCOPYFLAGS_EFI += --target=efi-app-$(EFIARCH)
 
+CPPFLAGS_REMOVE_crt0-efi-$(EFIARCH).o += $(CFLAGS_NON_EFI)
+CPPFLAGS_crt0-efi-$(EFIARCH).o += $(CFLAGS_EFI)
+
 ifeq ($(CONFIG_EFI_APP),y)
 
 PLATFORM_CPPFLAGS += $(CFLAGS_EFI)

arch/x86/include/asm/types.h

@@ -44,8 +44,11 @@ typedef __INT64_TYPE__ s64;
 typedef __UINT64_TYPE__ u64;
 #endif
 
+#ifdef CONFIG_EFI_STUB_64BIT
+#define BITS_PER_LONG 64
+#else
 #define BITS_PER_LONG 32
-
+#endif
 /* Dma addresses are 32-bits wide.  */
 
 typedef u32 dma_addr_t;

arch/x86/lib/efi/crt0-efi-x86_64.S

@@ -0,0 +1,51 @@
+/*
+ * crt0-efi-x86_64.S - x86_64 EFI startup code.
+ * Copyright (C) 1999 Hewlett-Packard Co.
+ * Contributed by David Mosberger <davidm@hpl.hp.com>.
+ * Copyright (C) 2005 Intel Co.
+ * Contributed by Fenghua Yu <fenghua.yu@intel.com>.
+ *
+ * All rights reserved.
+ * SPDX-License-Identifier:	BSD-3-Clause
+ */
+	.text
+	.align 4
+
+	.globl _start
+_start:
+	subq $8, %rsp
+	pushq %rcx
+	pushq %rdx
+
+0:
+	lea image_base(%rip), %rdi
+	lea _DYNAMIC(%rip), %rsi
+
+	popq %rcx
+	popq %rdx
+	pushq %rcx
+	pushq %rdx
+	call _relocate
+
+	popq %rdi
+	popq %rsi
+
+	call efi_main
+	addq $8, %rsp
+
+.exit:
+	ret
+
+	/*
+	 * hand-craft a dummy .reloc section so EFI knows it's a relocatable
+	 * executable:
+	 */
+	.data
+dummy:	.long	0
+
+#define IMAGE_REL_ABSOLUTE	0
+	.section .reloc, "a"
+label1:
+	.long	dummy-label1				/* Page RVA */
+	.long	10					/* Block Size (2*4+2) */
+	.word	(IMAGE_REL_ABSOLUTE << 12) +  0		/* reloc for dummy */