58 lines
2.9 KiB
C
58 lines
2.9 KiB
C
/*-*- 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 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#ifndef COSMOPOLITAN_LIBC_SYSV_MACROS_H_
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#define COSMOPOLITAN_LIBC_SYSV_MACROS_H_
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#ifdef __ASSEMBLER__
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#include "libc/macros.inc"
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/* clang-format off */
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/**
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* @fileoverview System Five jump slot generator.
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*
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* We need to pass a magic number to the SYSCALL instruction in %rax.
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* That's only possible to do in C using asm() macro wrappers, like in
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* Chromium's "System Call Support" library. This technique is simpler
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* to implement, gains us object-level ABI compatibility, hookability,
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* and the ability to support significantly more functions, without the
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* risk of slowing down builds too much with complicated headers.
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*/
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.macro .scall name:req num:req kw1 kw2
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.ifnb \kw2
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.align 16
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\name: movabs $\num,%rax
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jmp *systemfive(%rip)
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.else
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\name: push %rbp
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mov %rsp,%rbp
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movabs $\num,%rax
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.hookable
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call *systemfive(%rip)
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pop %rbp
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ret
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.endif
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.endfn \name,\kw1,\kw2
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.previous
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.endm
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/* clang-format on */
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#endif /* __ASSEMBLER__ */
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#endif /* COSMOPOLITAN_LIBC_SYSV_MACROS_H_ */
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