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dd53f31147
If you build a static ELF executable in `ld -q` mode (which leaves rela sections inside the binary) then you can run it through the elf2pe.com program afterwards, which will turn it into a PE executable. We have a new trick for defining WIN32 DLL imports in C without any assembly code. This also achieves the optimally tiny and perfect PE binary structure. We need this because it isn't possible to have a GNU ld linker script generate a PE file where the virtual pointer and the file pointer can drift apart. This post-linker can do that. One cool benefit is we can now use a smaller 512-byte alignment in the file, and an even bigger 64kb alignment for the segment virtual addresses, and the executable ends up being smaller. Another program introduced by this change is pecheck.com which can do extensive linting of PE static executables to help explain why Windows won't load it.
58 lines
2.7 KiB
ArmAsm
58 lines
2.7 KiB
ArmAsm
/*-*- mode:unix-assembly; indent-tabs-mode:t; tab-width:8; coding:utf-8 -*-│
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│vi: set et ft=asm ts=8 tw=8 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2023 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/macros.internal.h"
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// Invokes system call.
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//
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// This function has eight parameters. The first seven are for
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// arguments passed along to the system call. The eight is for
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// the magic number that indicates which system call is called
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//
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// The return value follows the Linux kernel convention, where
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// errors are returned as `-errno`. BSD systems are normalized
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// to follow this convention automatically.
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//
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// It's important to use a function call wrapper when invoking
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// syscall, because BSD kernels will unpredictably clobber any
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// volatile registers (unlike Linux). There's no overhead with
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// the extra call since a system call takes like a microsecond
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//
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// @return negative errno above -4096ul on error
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SystemCall:
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#ifdef __aarch64__
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mov x8,x7
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mov x16,x7
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mov x9,0
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adds x9,x9,0
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svc 0
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bcs 1f
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ret
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1: neg x0,x0
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ret
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#else
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mov %rcx,%r10
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mov 16(%rsp),%eax
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clc
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syscall
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jnc 1f
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neg %rax
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1: ret
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#endif
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.endfn SystemCall,globl
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