[U-Boot] [PATCH v3] x86: use EFI calling convention for efi_main on x86_64

[Bin Meng]

Hi Ivan,

On Fri, Jun 1, 2018 at 2:46 AM, Ivan Gorinov <ivan.gorinov at intel.com> wrote:
> 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.
> The arguments of efi_main() are also passed as unused arguments to the
> _relocate() function.
>
> Save efi_main() arguments in the startup code on x86_64;
> use EFI calling convention for _relocate() on x86_64;
> remove unused _relocate() arguments;

This should be a separate patch to remove unused _relocate arguments
for all arches (arm/x86/risc-v)

> consistently use EFI calling convention for efi_main() everywhere.
>
> Signed-off-by: Ivan Gorinov <ivan.gorinov at intel.com>
> ---
>  arch/x86/lib/crt0_x86_64_efi.S  | 21 ++++++++++-----------
>  arch/x86/lib/reloc_x86_64_efi.c |  3 +--
>  lib/efi/efi_app.c               |  3 ++-
>  lib/efi/efi_stub.c              |  3 ++-
>  4 files changed, 15 insertions(+), 15 deletions(-)
>
> diff --git a/arch/x86/lib/crt0_x86_64_efi.S b/arch/x86/lib/crt0_x86_64_efi.S
> index 989799f..3abb5e3 100644
> --- a/arch/x86/lib/crt0_x86_64_efi.S
> +++ b/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 at hpl.hp.com>.
> - * Copyright (C) 2005 Intel Co.
> + * Copyright (C) 2005 Intel Corporation
>   * Contributed by Fenghua Yu <fenghua.yu at intel.com>.
>   *
>   * All rights reserved.
> @@ -14,26 +14,25 @@
>         .globl _start
>  _start:
>         subq $8, %rsp
> +
>         pushq %rcx
>         pushq %rdx
>
> -0:
> -       lea image_base(%rip), %rdi
> -       lea _DYNAMIC(%rip), %rsi
> +       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:

nits: keep the .exit label name, as the x86 version uses the same
name, for consistency

>         addq $8, %rsp
>
> -.exit:
>         ret
>
>         /*
> diff --git a/arch/x86/lib/reloc_x86_64_efi.c b/arch/x86/lib/reloc_x86_64_efi.c
> index 34c5b2e..59d6f8d 100644
> --- a/arch/x86/lib/reloc_x86_64_efi.c
> +++ b/arch/x86/lib/reloc_x86_64_efi.c
> @@ -14,8 +14,7 @@
>  #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)
> +efi_status_t EFIAPI _relocate(long ldbase, Elf64_Dyn *dyn)
>  {
>         long relsz = 0, relent = 0;
>         Elf64_Rel *rel = 0;
> diff --git a/lib/efi/efi_app.c b/lib/efi/efi_app.c
> index c828093..3eb8eeb 100644
> --- a/lib/efi/efi_app.c
> +++ b/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;
> diff --git a/lib/efi/efi_stub.c b/lib/efi/efi_stub.c
> index 3138739..399d16b 100644
> --- a/lib/efi/efi_stub.c
> +++ b/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;
> --

Regards,
Bin