/* $NetBSD: efi_stub.S,v 1.1.1.1 2014/04/01 16:16:07 jakllsch Exp $ */
/*
* Function calling ABI conversion from Linux to EFI for x86_64
*
* Copyright (C) 2007 Intel Corp
* Bibo Mao <bibo.mao@intel.com>
* Huang Ying <ying.huang@intel.com>
* Copyright (C) 2012 Felipe Contreras <felipe.contreras@gmail.com>
*/
#if !defined(HAVE_USE_MS_ABI)
/*
* EFI calling conventions are documented at:
* http://msdn.microsoft.com/en-us/library/ms235286%28v=vs.80%29.aspx
* ELF calling conventions are documented at:
* http://www.x86-64.org/documentation/abi.pdf
*
* Basically here are the conversion rules:
* a) our function pointer is in %rdi
* b) rsi through r8 (elf) aka rcx through r9 (ms) require stack space
* on the MS side even though it's not getting used at all.
* c) 8(%rsp) is always aligned to 16 in ELF, so %rsp is shifted 8 bytes extra
* d) arguments are as follows: (elf -> ms)
* 1) rdi -> rcx (32 saved)
* 2) rsi -> rdx (32 saved)
* 3) rdx -> r8 (32 saved)
* 4) rcx -> r9 (32 saved)
* 5) r8 -> 32(%rsp) (32 saved)
* 6) r9 -> 40(%rsp) (48 saved)
* 7) 8(%rsp) -> 48(%rsp) (48 saved)
* 8) 16(%rsp) -> 56(%rsp) (64 saved)
* 9) 24(%rsp) -> 64(%rsp) (64 saved)
* 10) 32(%rsp) -> 72(%rsp) (80 saved)
* e) because the first argument we recieve in a thunker is actually the
* function to be called, arguments are offset as such:
* 0) rdi -> caller
* 1) rsi -> rcx (32 saved)
* 2) rdx -> rdx (32 saved)
* 3) rcx -> r8 (32 saved)
* 4) r8 -> r9 (32 saved)
* 5) r9 -> 32(%rsp) (32 saved)
* 6) 8(%rsp) -> 40(%rsp) (48 saved)
* 7) 16(%rsp) -> 48(%rsp) (48 saved)
* 8) 24(%rsp) -> 56(%rsp) (64 saved)
* 9) 32(%rsp) -> 64(%rsp) (64 saved)
* 10) 40(%rsp) -> 72(%rsp) (80 saved)
* f) arguments need to be moved in opposite order to avoid clobbering
*/
#define ENTRY(name) \
.globl name; \
name:
ENTRY(efi_call0)
subq $40, %rsp
call *%rdi
addq $40, %rsp
ret
ENTRY(efi_call1)
subq $40, %rsp
mov %rsi, %rcx
call *%rdi
addq $40, %rsp
ret
ENTRY(efi_call2)
subq $40, %rsp
/* mov %rdx, %rdx */
mov %rsi, %rcx
call *%rdi
addq $40, %rsp
ret
ENTRY(efi_call3)
subq $40, %rsp
mov %rcx, %r8
/* mov %rdx, %rdx */
mov %rsi, %rcx
call *%rdi
addq $40, %rsp
ret
ENTRY(efi_call4)
subq $40, %rsp
mov %r8, %r9
mov %rcx, %r8
/* mov %rdx, %rdx */
mov %rsi, %rcx
call *%rdi
addq $40, %rsp
ret
ENTRY(efi_call5)
subq $40, %rsp
mov %r9, 32(%rsp)
mov %r8, %r9
mov %rcx, %r8
/* mov %rdx, %rdx */
mov %rsi, %rcx
call *%rdi
addq $40, %rsp
ret
ENTRY(efi_call6)
subq $56, %rsp
mov 56+8(%rsp), %rax
mov %rax, 40(%rsp)
mov %r9, 32(%rsp)
mov %r8, %r9
mov %rcx, %r8
/* mov %rdx, %rdx */
mov %rsi, %rcx
call *%rdi
addq $56, %rsp
ret
ENTRY(efi_call7)
subq $56, %rsp
mov 56+16(%rsp), %rax
mov %rax, 48(%rsp)
mov 56+8(%rsp), %rax
mov %rax, 40(%rsp)
mov %r9, 32(%rsp)
mov %r8, %r9
mov %rcx, %r8
/* mov %rdx, %rdx */
mov %rsi, %rcx
call *%rdi
addq $56, %rsp
ret
ENTRY(efi_call8)
subq $72, %rsp
mov 72+24(%rsp), %rax
mov %rax, 56(%rsp)
mov 72+16(%rsp), %rax
mov %rax, 48(%rsp)
mov 72+8(%rsp), %rax
mov %rax, 40(%rsp)
mov %r9, 32(%rsp)
mov %r8, %r9
mov %rcx, %r8
/* mov %rdx, %rdx */
mov %rsi, %rcx
call *%rdi
addq $72, %rsp
ret
ENTRY(efi_call9)
subq $72, %rsp
mov 72+32(%rsp), %rax
mov %rax, 64(%rsp)
mov 72+24(%rsp), %rax
mov %rax, 56(%rsp)
mov 72+16(%rsp), %rax
mov %rax, 48(%rsp)
mov 72+8(%rsp), %rax
mov %rax, 40(%rsp)
mov %r9, 32(%rsp)
mov %r8, %r9
mov %rcx, %r8
/* mov %rdx, %rdx */
mov %rsi, %rcx
call *%rdi
addq $72, %rsp
ret
ENTRY(efi_call10)
subq $88, %rsp
mov 88+40(%rsp), %rax
mov %rax, 72(%rsp)
mov 88+32(%rsp), %rax
mov %rax, 64(%rsp)
mov 88+24(%rsp), %rax
mov %rax, 56(%rsp)
mov 88+16(%rsp), %rax
mov %rax, 48(%rsp)
mov 88+8(%rsp), %rax
mov %rax, 40(%rsp)
mov %r9, 32(%rsp)
mov %r8, %r9
mov %rcx, %r8
/* mov %rdx, %rdx */
mov %rsi, %rcx
call *%rdi
addq $88, %rsp
ret
#endif