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. 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;

consistently use EFI calling convention for efi_main() everywhere.

Signed-off-by Ivan Gorinov <[email protected]>

---
 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(-)

arch/x86/lib/crt0_x86_64_efi.S +4 -7

index 989799f..096f347 100644
@@ -3,7 +3,7 @@
  * crt0-efi-x86_64.S - x86_64 EFI startup code.
  * Copyright (C) 1999 Hewlett-Packard Co.
  * Contributed by David Mosberger <[email protected]>.
- * Copyright (C) 2005 Intel Co.
+ * Copyright (C) 2005 Intel Corporation
  * Contributed by Fenghua Yu <[email protected]>.
  *
  * 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

arch/x86/lib/crt0_x86_64_efi.S +1 -1

        call efi_main
+.exit:
        addq $8, %rsp
 
-.exit:
        ret
 
        /*

arch/x86/lib/reloc_x86_64_efi.c +1 -2

index 34c5b2e..59d6f8d 100644
@@ -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;

lib/efi/efi_app.c +2 -1

index c828093..3eb8eeb 100644
@@ -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 +0 -0

index 3138739..399d16b 100644

Hi Ivan,

Quoted 12 lines · Ivan Gorinov

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.

Quoted 8 lines

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;

Thanks for working on this. But as I mentioned previously, the removal of _relocate() arguments should be in a separate patch. This patch should only deal with the calling convention changes.

So we should have 4 patches:
[1/4]: efi: calling convention changes for x86_64
[2/4]: x86: remove unused _relocate() arguments
[3/4]: arm: remove unused _relocate() arguments
[4/4]: riscv: remove unused _relocate() arguments

Quoted 10 lines

consistently use EFI calling convention for efi_main() everywhere.

Signed-off-by Ivan Gorinov <[email protected]>

---
 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(-)

EFI image handle and system table are not used in _relocate().

Signed-off-by Ivan Gorinov <[email protected]>

---
 arch/arm/lib/crt0_aarch64_efi.S  | 2 --
 arch/arm/lib/crt0_arm_efi.S      | 2 --
 arch/arm/lib/reloc_aarch64_efi.c | 3 +--
 arch/arm/lib/reloc_arm_efi.c     | 3 +--
 4 files changed, 2 insertions(+), 8 deletions(-)

arch/arm/lib/crt0_aarch64_efi.S +0 -2

index 5b6c384..0db4360 100644
@@ -122,8 +122,6 @@ _start:
        mov             x29, sp
 
        stp             x0, x1, [sp, #16]
-       mov             x2, x0
-       mov             x3, x1
        adr             x0, ImageBase
        adrp            x1, _DYNAMIC
        add             x1, x1, #:lo12:_DYNAMIC

arch/arm/lib/crt0_arm_efi.S +0 -2

index 0f296f3..23db49f 100644
@@ -119,8 +119,6 @@ section_table:
 _start:
        stmfd           sp!, {r0-r2, lr}
 
-       mov             r2, r0
-       mov             r3, r1
        adr             r1, .L_DYNAMIC
        ldr             r0, [r1]
        add             r1, r0, r1

arch/arm/lib/reloc_aarch64_efi.c +0 -0

index 38c13d3..c648fe4 100644

arch/arm/lib/reloc_aarch64_efi.c +0 -0

 {
        long relsz = 0, relent = 0;
        Elf64_Rela *rel = 0;

arch/arm/lib/reloc_arm_efi.c +0 -0

index 6232e3f..336a98a 100644

EFI image handle and system table are not used in _relocate().

Signed-off-by Ivan Gorinov <[email protected]>

---
 arch/riscv/lib/reloc_riscv_efi.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

arch/riscv/lib/reloc_riscv_efi.c +0 -0

index 8b4b2b1..51b7520 100644

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;
consistently use EFI calling convention for efi_main() everywhere.

v4:
Keeping .exit label in x86_64 startup code;
Also removed the unused _relocate() arguments for arm, x86, riscv.

v3:
Updated patch description.

v2:
Added EFIABI to _relocate() declaration.

Ivan Gorinov (4):
x86: use EFI calling convention for efi_main on x86_64
arm: Remove unused _relocate arguments
x86: Remove unused _relocate arguments
riscv: Remove unused _relocate arguments

 arch/arm/lib/crt0_aarch64_efi.S  |  2 --
 arch/arm/lib/crt0_arm_efi.S      |  2 --
 arch/arm/lib/reloc_aarch64_efi.c |  3 +--
 arch/arm/lib/reloc_arm_efi.c     |  3 +--
 arch/riscv/lib/reloc_riscv_efi.c |  3 +--
 arch/x86/lib/crt0_x86_64_efi.S   | 21 ++++++++++-----------
 arch/x86/lib/reloc_ia32_efi.c    |  3 +--
 arch/x86/lib/reloc_x86_64_efi.c  |  3 +--
 lib/efi/efi_app.c                |  3 ++-
 lib/efi/efi_stub.c               |  3 ++-
 10 files changed, 19 insertions(+), 27 deletions(-)