/* $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 * Huang Ying * Copyright (C) 2012 Felipe Contreras */ #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