x86: Add support for U-Boot as an EFI application

Add the required x86 glue code. This includes the initial start-up,
relocation and jumping to efi_main(). We also need to avoid fiddling with
interrupts.

Signed-off-by: Ben Stoltz <stoltz@google.com>
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

2 files changed, 124 insertions, 0 deletions

diff --git a/arch/x86/lib/efi/crt0-efi-ia32.S b/arch/x86/lib/efi/crt0-efi-ia32.S
new file mode 100644
index 0000000..30e5eb0
--- /dev/null
+++ b/arch/x86/lib/efi/crt0-efi-ia32.S
@@ -0,0 +1,52 @@
+/*
+ * crt0-efi-ia32.S - x86 EFI startup code.
+ *
+ * Copyright (C) 1999 Hewlett-Packard Co.
+ * Contributed by David Mosberger <davidm@hpl.hp.com>.
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier:	BSD-3-Clause
+ */
+
+	.text
+	.align 4
+
+	.globl _start
+_start:
+	pushl %ebp
+	movl %esp,%ebp
+
+	pushl 12(%ebp)			# copy "image" argument
+	pushl  8(%ebp)			# copy "systab" argument
+
+	call 0f
+0:	popl %eax
+	movl %eax,%ebx
+
+	addl $image_base-0b,%eax	# %eax = ldbase
+	addl $_DYNAMIC-0b,%ebx		# %ebx = _DYNAMIC
+
+	pushl %ebx			# pass _DYNAMIC as second argument
+	pushl %eax			# pass ldbase as first argument
+	call _relocate
+	popl %ebx
+	popl %ebx
+	testl %eax,%eax
+	jne .exit
+	call efi_main		# call app with "image" and "systab" argument
+
+.exit:	leave
+	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
+	.long	dummy					/* Page RVA */
+	.long	10					/* Block Size (2*4+2) */
+	.word	(IMAGE_REL_ABSOLUTE << 12) +  0		/* reloc for dummy */
diff --git a/arch/x86/lib/efi/reloc_ia32.c b/arch/x86/lib/efi/reloc_ia32.c
new file mode 100644
index 0000000..4d68255
--- /dev/null
+++ b/arch/x86/lib/efi/reloc_ia32.c
@@ -0,0 +1,72 @@
+/*
+ * reloc_ia32.c - position independent x86 ELF shared object relocator
+ * Copyright (C) 1999 Hewlett-Packard Co.
+ * Contributed by David Mosberger <davidm@hpl.hp.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, Elf32_Dyn *dyn, efi_handle_t image,
+		       struct efi_system_table *systab)
+{
+	long relsz = 0, relent = 0;
+	Elf32_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_REL:
+			rel = (Elf32_Rel *)((unsigned long)dyn[i].d_un.d_ptr +
+								ldbase);
+			break;
+
+		case DT_RELSZ:
+			relsz = dyn[i].d_un.d_val;
+			break;
+
+		case DT_RELENT:
+			relent = dyn[i].d_un.d_val;
+			break;
+
+		case DT_RELA:
+			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 (ELF32_R_TYPE(rel->r_info)) {
+		case R_386_NONE:
+			break;
+
+		case R_386_RELATIVE:
+			addr = (unsigned long *)(ldbase + rel->r_offset);
+			*addr += ldbase;
+			break;
+
+		default:
+			break;
+		}
+		rel = (Elf32_Rel *)((char *)rel + relent);
+		relsz -= relent;
+	}
+
+	return EFI_SUCCESS;
+}