x86: Add relocation and link script for a 64-bit EFI application

Add a linker script and relocation code for building 64-bit EFI
applications. This can be used for the EFI stub.

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>

arch/x86/cpu/efi/elf_x86_64_efi.lds

+/*
+ * U-Boot EFI linker script
+ *
+ * SPDX-License-Identifier:	BSD-2-Clause
+ *
+ * Modified from usr/lib32/elf_x86_64_efi.lds in gnu-efi
+ */
+
+#include <config.h>
+
+OUTPUT_FORMAT("elf64-x86-64", "elf64-x86-64", "elf64-x86-64")
+OUTPUT_ARCH(i386:x86-64)
+ENTRY(_start)
+SECTIONS
+{
+	image_base = .;
+	.hash : { *(.hash) }	/* this MUST come first, EFI expects it */
+	. = ALIGN(4096);
+	.eh_frame : {
+		*(.eh_frame)
+	}
+
+	. = ALIGN(4096);
+
+	.text : {
+		*(.text)
+		*(.text.*)
+		*(.gnu.linkonce.t.*)
+	}
+
+	. = ALIGN(4096);
+
+	.reloc : {
+		*(.reloc)
+	}
+
+	. = ALIGN(4096);
+
+	.data : {
+		*(.rodata*)
+		*(.got.plt)
+		*(.got)
+		*(.data*)
+		*(.sdata)
+		/* the EFI loader doesn't seem to like a .bss section, so we stick
+		 * it all into .data: */
+		*(.sbss)
+		*(.scommon)
+		*(.dynbss)
+		*(.bss)
+		*(COMMON)
+		*(.rel.local)
+
+		/* U-Boot lists and device tree */
+		. = ALIGN(8);
+		*(SORT(.u_boot_list*));
+		. = ALIGN(8);
+		*(.dtb*);
+	}
+
+	. = ALIGN(4096);
+	.dynamic : { *(.dynamic) }
+	. = ALIGN(4096);
+
+	.rela : {
+		*(.rela.data*)
+		*(.rela.got)
+		*(.rela.stab)
+	}
+
+	. = ALIGN(4096);
+	.dynsym : { *(.dynsym) }
+	. = ALIGN(4096);
+	.dynstr : { *(.dynstr) }
+	. = ALIGN(4096);
+	.ignored.reloc : {
+		*(.rela.reloc)
+		*(.eh_frame)
+		*(.note.GNU-stack)
+	}
+
+	.comment 0 : { *(.comment) }
+}

arch/x86/lib/efi/reloc_x86_64.c

+/*
+ * reloc_x86_64.c - position independent x86_64 ELF shared object relocator
+ * 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
+ */
+
+#include <common.h>
+#include <efi.h>
+#include <elf.h>
+#include <asm/elf.h>
+
+efi_status_t _relocate(long ldbase, Elf64_Dyn *dyn, efi_handle_t image,
+		       struct efi_system_table *systab)
+{
+	long relsz = 0, relent = 0;
+	Elf64_Rel *rel = 0;
+	unsigned long *addr;
+	int i;
+
+	for (i = 0; dyn[i].d_tag != DT_NULL; ++i) {
+		switch (dyn[i].d_tag) {
+		case DT_RELA:
+			rel = (Elf64_Rel *)
+				((unsigned long)dyn[i].d_un.d_ptr + ldbase);
+			break;
+		case DT_RELASZ:
+			relsz = dyn[i].d_un.d_val;
+			break;
+		case DT_RELAENT:
+			relent = dyn[i].d_un.d_val;
+			break;
+		default:
+			break;
+		}
+	}
+
+	if (!rel && relent == 0)
+		return EFI_SUCCESS;
+
+	if (!rel || relent == 0)
+		return EFI_LOAD_ERROR;
+
+	while (relsz > 0) {
+		/* apply the relocs */
+		switch (ELF64_R_TYPE(rel->r_info)) {
+		case R_X86_64_NONE:
+			break;
+		case R_X86_64_RELATIVE:
+			addr = (unsigned long *)(ldbase + rel->r_offset);
+			*addr += ldbase;
+			break;
+		default:
+			break;
+		}
+		rel = (Elf64_Rel *)((char *)rel + relent);
+		relsz -= relent;
+	}
+
+	return EFI_SUCCESS;
+}