x86: use EFI calling convention for efi_main on x86_64

UEFI specifies the calling convention used in Microsoft compilers;
first arguments of a function are passed in (%rcx, %rdx, %r8, %r9).

All other compilers use System V ABI by default, passing first integer
arguments of a function in (%rdi, %rsi, %rdx, %rcx, %r8, %r9).

These ABI also specify different sets of registers that must be preserved
across function calls (callee-saved).

GCC allows using the Microsoft calling convention by adding the ms_abi
attribute to a function declaration.

Current EFI implementation in U-Boot specifies EFIAPI for efi_main()
in the test apps but uses default calling convention in lib/efi.

Save efi_main() arguments in the startup code on x86_64;
use EFI calling convention for _relocate() on x86_64;
consistently use EFI calling convention for efi_main() everywhere.

Signed-off-by: Ivan Gorinov <ivan.gorinov@intel.com>
Reviewed-by: Alexander Graf <agraf@suse.de>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>

arch/x86/lib/crt0_x86_64_efi.S

@@ -3,7 +3,7 @@
  * 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.
+ * Copyright (C) 2005 Intel Corporation
  * Contributed by Fenghua Yu <fenghua.yu@intel.com>.
  *
  * All rights reserved.
@@ -14,26 +14,28 @@
 	.globl _start
 _start:
 	subq $8, %rsp
+
 	pushq %rcx
 	pushq %rdx
 
-0:
-	lea image_base(%rip), %rdi
-	lea _DYNAMIC(%rip), %rsi
+	mov %rcx, %r8
+	mov %rdx, %r9
+
+	lea image_base(%rip), %rcx
+	lea _DYNAMIC(%rip), %rdx
 
-	popq %rcx
-	popq %rdx
-	pushq %rcx
-	pushq %rdx
 	call _relocate
 
-	popq %rdi
-	popq %rsi
+	popq %rdx
+	popq %rcx
+
+	testq %rax, %rax
+	jnz .exit
 
 	call efi_main
+.exit:
 	addq $8, %rsp
 
-.exit:
 	ret
 
 	/*

lib/efi/efi_app.c

@@ -96,7 +96,8 @@ static void free_memory(struct efi_priv *priv)
  * U-Boot. If it returns, EFI will continue. Another way to get back to EFI
  * is via reset_cpu().
  */
-efi_status_t efi_main(efi_handle_t image, struct efi_system_table *sys_table)
+efi_status_t EFIAPI efi_main(efi_handle_t image,
+			     struct efi_system_table *sys_table)
 {
 	struct efi_priv local_priv, *priv = &local_priv;
 	efi_status_t ret;

lib/efi/efi_stub.c

@@ -268,7 +268,8 @@ static void add_entry_addr(struct efi_priv *priv, enum efi_entry_t type,
  * This function is called by our EFI start-up code. It handles running
  * U-Boot. If it returns, EFI will continue.
  */
-efi_status_t efi_main(efi_handle_t image, struct efi_system_table *sys_table)
+efi_status_t EFIAPI efi_main(efi_handle_t image,
+			     struct efi_system_table *sys_table)
 {
 	struct efi_priv local_priv, *priv = &local_priv;
 	struct efi_boot_services *boot = sys_table->boottime;