mirror of
https://github.com/jart/cosmopolitan.git
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458 lines
18 KiB
ArmAsm
458 lines
18 KiB
ArmAsm
/*-*- mode:unix-assembly; indent-tabs-mode:t; tab-width:8; coding:utf-8 -*-│
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│ vi: set noet ft=asm ts=8 sw=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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│ 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/intrin/strace.internal.h"
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#include "libc/dce.h"
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#include "libc/macros.internal.h"
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#include "libc/thread/pt.internal.h"
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#define SIG_IGN 1
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/* ▄▄▄
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▄▄▄ ▀▓▓▒▄
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▄▓▒▒░ ▀▓▒▒▒▄
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▄▓▓▓▒▀ ▄▄▄▄ ▒▓▒▒░▒▄
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▄▓▓▓▒▓ ▄▄▓██▓▓▓▓▒▒▒▒▓▓▄▄▓▓▒▒▒░░▒
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▓▓▓▓▒▒▒▄▄ ░▒█▓▓▓▓▓▓▓▓▓▒▒▒▒▒▒▒▒▒▒▒▓▒░░▒░
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██▓▓▓▒▒░░▒▒▒▒▓▓▓▓▓▓▒▓▒░▒▒░▀▒▒▒▒░▀░▒▒▒░▒
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▓▓▓▓▓▓▓▒▒▒▒▒▒▓▓▒▓▓▒▒▒░▒▒░░ ░▒▒░ ░▒▒▒▒
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▀▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▒▒░░▒░░ ░▒▒ ░ ▀▒▒
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▀▓▓█▓▓▓▓▓▓▓▓▓▓▒▒░░▒▒░░ ░░░▓░ ▓░░░▒
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▀▀█▓███▓▓▓▓▓▒▒░░░▒░░ ░█▓░█▓░█▓▓▄▒░
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░▓██▓▓▓▓▓▒▒░░░▒░░ ░████▓▒▓█▓▀░▀▄
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░▓██▓▓▓▓▓▒▒▒░░░▒░░ ▒██▓▒▒▒▒▒▒░░░▒
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████▓▓▓▓▓▒▒▒▒▒▒▒▒▒░░▒▓▓▒░░░░▒░░░▒░ ░░░░░
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░▓███▓▓▓▓▓▒▒░░░░░░░▒▒▒▒▒▒▒▒▒▒▒░░░ ░░░░░ ░
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▓███▓▓▓▓▓▒▓▒▒▒▒░░░░░░░░░▒▓▒▒░▀ ░░░ ░░░░░
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▀▒██▓▓▓▓▒▒▒▓▓▓▓▒▒▒▒▒▒▒▓▀▀░ ░░░░░░░░░ ░
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▓▓▓▓▓▓▓▒▓▒▒▒▒▓▓▓▒▀░ ░░░░░▄░░░ ░░░ ░░░░░░
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▓▓▓▒▒▒▒▒▒▒▒▒▒▒▓ █▓▒░░▒░░░░ ░░░░░░░░
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▄▓▓▓▒▒▒▒▒░░░░░░░▒▄▄▄░▒▓▓▒▒░▀░
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░▓█▓▓▒▒▒▒▒▒▒▒▒▒▒▒▒▒▓▓▓▓▓▓▒░░░▒ besiyata
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▓▓█▓▓▒▓▓▓▒▒▒░░░░░░▒▓▓▓▓▒▒▒▒▒░ dishmaya
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▓▓█▓▓▓▓▓▓▒▒▒░░░░░░░▒▓▓▒▀▀▀
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▄▄▄▒▒▓▓█▓▓▓▓▓▀▀▀▀▀ ▓▓▓▓▓▒▒▒▒▒▒▒▒▒▒▒▒▒▀░░▀░░▒▒▒░░░ ░░░░░
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▄▓▓▓▒▀▀ ▓▒▓▓▓▓▓▒▒▒▒▒▒▒▒▓░░░ ▒▒▒░░░░░░░░▒
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█▓▓▒ ▄▄▄ ▀▓▒▓▒▒▒▓▓▓▓▓▓▒▒▒░░░░░░░░░▒▒░░░░░░░
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▀▓▓▓▓▒▄▄▒▒▒▒▒▒▄▄ ▀▀▀▀░░▒▒▒▒░░░░░░
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▀▀▀▓▓▓▓▒▒▒▒▒▓▓▄▄
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╔────────────────────────────────────────────────────────────────────────────│─╗
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│ cosmopolitan § bell system five » system call support ─╬─│┼
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╚────────────────────────────────────────────────────────────────────────────│*/
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.initbss 300,_init_systemfive
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// Performs System Five System Call.
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//
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// Cosmopolitan is designed to delegate all function calls into the
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// Linux, FreeBSD, OpenBSD, and XNU kernels via this function, with
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// few exceptions. This function should generally only be called by
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// generated thunks in the libc/sysv/syscalls/ directory.
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//
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// It's safe to call this function on Windows, where it will always
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// return -1 with errno == ENOSYS. Further note that -1 is the only
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// return value that means error, a common anti-pattern is to check
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// for values less than 0 (which is more problematic on 32-bit).
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//
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// It is important to consider that system calls are one order of a
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// magnitude more expensive than normal function calls. For example
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// getpid() on Linux usually takes 500ns, and cached i/o calls will
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// take 1µs or more. So we don't need to inline them like Chromium.
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//
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// Another thing to consider is that BSDs only loosely follow the
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// System Five ABI for the SYSCALL instruction. For example Linux
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// always follows the six argument limit but the FreeBSD sendfile
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// system call accepts a seventh argument that is passed on stack
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// and OpenBSD modifies functions like mmap so that the sixth arg
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// is passed on the stack. There's also the carry flag convention
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// that XNU, FreeBSD, and OpenBSD inherited from 386BSD aka Jolix
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//
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// @param %rax function ordinal supplied by jump slot
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// @param %rdi,%rsi,%rdx,%rcx,%r8,%r9 and rest on stack
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// @return %rax:%rdx is result, or -1 w/ errno on error
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// @clob %rcx,%r10,%r11
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// @see syscalls.sh
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__systemfive:
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.quad 0
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.endobj __systemfive,globl,hidden
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__pid: .quad 0
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.endobj __pid,globl,hidden
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.previous
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systemfive_cp:
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push %rbp
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mov %rsp,%rbp // so backtraces work
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systemfive_cancellable: // our pthread_cancel() miracle code
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cmpb $0,__tls_enabled(%rip) // inspired by the musl libc design!
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je 1f // we handle linux and bsd together!
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mov %fs:0,%r10 // CosmoTib::tib_self
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mov 0x28(%r10),%r10 // CosmoTib::tib_pthread
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test %r10,%r10 // is it a posix thread?
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jz 1f // it's spawn() probably
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testb $PT_NOCANCEL,0x00(%r10) // PosixThread::flags
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jnz 1f // canceler no cancelling
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#if IsModeDbg()
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testb $PT_INCANCEL,0x00(%r10)
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jz 5f
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#endif
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cmpl $0,0x04(%r10) // PosixThread::cancelled
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jne systemfive_cancel // we will tail call below
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1: mov %rcx,%r10 // move the fourth argument
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clc // no cancellable system calls exist
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syscall // that have 7+ args on the bsd OSes
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systemfive_cancellable_end: // i/o calls park here for long time
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pop %rbp
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jnc 2f
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neg %rax // turns bsd errno to system v errno
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2: cmp $-4095,%rax // but we still check again on eintr
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jae 3f // branch because system call failed
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ret // done if the system call succeeded
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3: neg %eax // now examine the nature of failure
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cmp EINTR(%rip),%eax // did the SIGTHR cancel our IO call
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jne systemfive_errno // werent interrupted by OnSigCancel
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cmpb $0,__tls_enabled(%rip) // make sure it's safe to grab %fs:0
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je systemfive_errno // tls is disabled we can't continue
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mov %fs:0,%rcx // CosmoTib::tib_self
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mov 0x28(%rcx),%rcx // CosmoTib::tib_pthread
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test %rcx,%rcx // is it a posix thread?
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jz systemfive_errno // it's spawn() probably
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testb $PT_NOCANCEL,0x00(%rcx) // PosixThread::flags
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jnz systemfive_errno // cancellation is disabled
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cmpl $0,0x04(%rcx) // PosixThread::cancelled
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je systemfive_errno // we aren't actually cancelled
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jmp 4f // now we are in fact cancelled
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systemfive_cancel: // SIGTHR will jump here too
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pop %rbp
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4: jmp _pthread_cancel_ack // tail call
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.weak _pthread_cancel_ack // must be linked if we're cancelled
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#if IsModeDbg()
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not_a_cancellation_point: // need BEGIN/END_CANCELLATION_POINT
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nop
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.weak report_cancellation_point
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5: ezlea report_cancellation_point,cx
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test %rcx,%rcx
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jz 6f
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call *%rcx
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6: ud2
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nop
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#endif
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.globl systemfive_cancellable_end
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.globl systemfive_cancellable
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.globl systemfive_cancel
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.endfn systemfive_cp
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.Lanchorpoint:
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#if SupportsLinux() || SupportsMetal()
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systemfive_linux:
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and $0xfff,%eax // remove nonlinux bits from ordinal
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cmp $0xfff,%eax // checks if unsupported by platform
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je systemfive_enosys // never taken branches cost nothing
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btr $11,%eax // 0x800 means a call is cancellable
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jc systemfive_cp // it is handled by the holiest code
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mov %rcx,%r10 // syscall instruction clobbers %rcx
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push %rbp // linux never reads args from stack
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mov %rsp,%rbp // having frame will help backtraces
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syscall // this is known as a context switch
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pop %rbp // next we check to see if it failed
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cmp $-4095,%rax // system five nexgen32e abi § a.2.1
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jae systemfive_error // encodes errno as neg return value
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ret
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.endfn systemfive_linux,globl,hidden
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systemfive_error:
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neg %eax
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// 𝑠𝑙𝑖𝑑𝑒
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.endfn systemfive_error,globl,hidden
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#endif
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systemfive_errno:
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xchg %eax,%ecx
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.errno
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mov %ecx,(%rax) // normalize to c library convention
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push $-1 // negative one is only error result
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pop %rax // the push pop is to save code size
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ret
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.endfn systemfive_errno,globl,hidden
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systemfive_enosys:
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mov ENOSYS(%rip),%eax
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jmp systemfive_errno
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.endfn systemfive_enosys,globl,hidden
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#if SupportsNetbsd()
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systemfive_netbsd:
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shr $4*13,%rax
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jmp systemfive_bsdscrub
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.endfn systemfive_netbsd,globl,hidden
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#endif
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#if SupportsOpenbsd()
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systemfive_openbsd:
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shr $4*10,%rax
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jmp systemfive_bsdscrub
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.endfn systemfive_openbsd,globl,hidden
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#endif
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#if SupportsFreebsd()
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systemfive_freebsd:
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shr $4*7,%rax
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movzwl %ax,%eax
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// 𝑠𝑙𝑖𝑑𝑒
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.endfn systemfive_freebsd,globl,hidden
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#endif
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#if SupportsBsd()
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systemfive_bsdscrub:
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and $0xfff,%eax
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// 𝑠𝑙𝑖𝑑𝑒
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.endfn systemfive_bsdscrub,globl,hidden
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systemfive_bsd:
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cmp $0xfff,%ax
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je systemfive_enosys
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btr $11,%eax // checks/reset the 800 cancellable bit
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jc systemfive_cp
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mov %rcx,%r10
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syscall // bsd will need arg on stack sometimes
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jc systemfive_errno // bsd sets carry flag if %rax is errno
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ret
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.endfn systemfive_bsd
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#endif
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#if SupportsXnu()
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systemfive_xnu:
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// 0x?????????2153??? // how syscalls.sh encodes xnu ordinals
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// │└┴┴┐
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// │ ├┬┐
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// 0x0000000002000153 // how xnu wants ordinals to be encoded
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mov %eax,%r11d
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and $0x0f000000,%r11d
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shl $8,%eax
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shr $20,%eax
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or %r11d,%eax
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jmp systemfive_bsd
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.endfn systemfive_xnu,globl,hidden
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#endif
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.previous
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// Initializes System Five system call support.
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//
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// (1) Extracts parameters passed by kernel
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// (2) Detects OS without issuing system calls
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// (3) Unpacks magnums from libc/sysv/consts.sh
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// (4) Replaces stack with one we control
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//
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// @param %r15 is auxv
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// @note OpenBSD devs: let us know if you start using auxv
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.init.start 300,_init_systemfive
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push %rbx
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push %rsi
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// Detect the operating system.
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mov __hostos(%rip),%eax
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#if SupportsWindows() || SupportsXnu() || SupportsFreebsd()
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// set by libc/ape.S for XNU
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// set by libc/crt/crt.S for XNU/FreeBSD
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// set by libc/nt/winmain.greg.c for New Technology
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test %eax,%eax
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jnz _init_systemfive_detected // os is already known
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#endif
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#if SupportsOpenbsd()
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cmpq $0,(%r15) // OpenBSD has no auxv
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jnz 0f
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mov $_HOSTOPENBSD,%al
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jmp _init_systemfive_detected
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0:
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#endif
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#if SupportsNetbsd()
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xor %ecx,%ecx
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0: cmpq $2014,(%r15,%rcx,8) // NetBSD's AT_EXECFN
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jne 1f
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mov $_HOSTNETBSD,%al
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jmp _init_systemfive_detected
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1: cmpq $0,(%r15,%rcx,8)
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lea 2(%ecx),%ecx
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jnz 0b
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2:
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#endif
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mov $_HOSTLINUX,%al
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_init_systemfive_detected:
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mov %eax,__hostos(%rip)
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bsr %eax,%eax
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mov $_init_systemfive_jmptab,%ebx
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movzbl (%rbx,%rax),%eax
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lea (%rbx,%rax),%eax
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jmp *%rax
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_init_systemfive_jmptab:
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.byte _init_systemfive_linux-_init_systemfive_jmptab
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.byte _init_systemfive_metal-_init_systemfive_jmptab
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.byte _init_systemfive_windows-_init_systemfive_jmptab
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.byte _init_systemfive_xnu-_init_systemfive_jmptab
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.byte _init_systemfive_openbsd-_init_systemfive_jmptab
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.byte _init_systemfive_freebsd-_init_systemfive_jmptab
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.byte _init_systemfive_netbsd-_init_systemfive_jmptab
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.endobj _init_systemfive_jmptab
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_init_systemfive_linux:
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#if SupportsLinux()
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pushb systemfive_linux-.Lanchorpoint
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mov $syscon_linux,%esi
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jmp _init_systemfive_os
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#endif
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.endfn _init_systemfive_linux
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_init_systemfive_metal:
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#if SupportsMetal()
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pushb systemfive_enosys-.Lanchorpoint
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mov $syscon_linux,%esi
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jmp _init_systemfive_os
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#endif
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.endfn _init_systemfive_metal
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_init_systemfive_windows:
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#if SupportsWindows()
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pushb systemfive_enosys-.Lanchorpoint
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mov $syscon_windows,%esi
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jmp _init_systemfive_os
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#endif
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.endfn _init_systemfive_windows
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_init_systemfive_xnu:
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#if SupportsXnu()
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pushb systemfive_xnu-.Lanchorpoint
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mov $syscon_xnu,%esi
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jmp _init_systemfive_os
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#endif
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.endfn _init_systemfive_xnu
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_init_systemfive_openbsd:
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#if SupportsOpenbsd()
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pushb systemfive_openbsd-.Lanchorpoint
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mov $syscon_openbsd,%esi
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jmp _init_systemfive_os
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#endif
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.endfn _init_systemfive_openbsd
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_init_systemfive_freebsd:
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#if SupportsFreebsd()
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pushb systemfive_freebsd-.Lanchorpoint
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mov $syscon_freebsd,%esi
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jmp _init_systemfive_os
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#endif
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.endfn _init_systemfive_freebsd
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_init_systemfive_netbsd:
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#if SupportsNetbsd()
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pushb systemfive_netbsd-.Lanchorpoint
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mov $syscon_netbsd,%esi
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||
// 𝑠𝑙𝑖𝑑𝑒
|
||
#endif
|
||
.endfn _init_systemfive_netbsd
|
||
_init_systemfive_os:
|
||
pop %rax
|
||
add $.Lanchorpoint,%eax
|
||
stosq #→ __systemfive
|
||
// 𝑠𝑙𝑖𝑑𝑒
|
||
.endfn _init_systemfive_os
|
||
_init_systemfive_magnums:
|
||
push %rdi
|
||
mov $syscon_start,%edi
|
||
2: cmp $syscon_end,%edi
|
||
jnb 5f
|
||
xor %ebx,%ebx
|
||
xor %ecx,%ecx
|
||
xor %edx,%edx
|
||
3: lodsb // decodes uleb128
|
||
movzbl %al,%edx
|
||
and $127,%dl
|
||
shl %cl,%rdx
|
||
or %rdx,%rbx
|
||
add $7,%cl
|
||
test $128,%al
|
||
jnz 3b
|
||
xchg %rbx,%rax
|
||
stosq
|
||
#if SYSDEBUG
|
||
inc %r8d
|
||
#endif
|
||
jmp 2b
|
||
5: nop
|
||
#if SYSDEBUG
|
||
push %rdi
|
||
push %rsi
|
||
push %r8
|
||
call __describe_os
|
||
mov %rax,%rdx
|
||
pop %r8
|
||
.weak __stracef
|
||
ezlea __stracef,ax
|
||
test %rax,%rax
|
||
jz 5f
|
||
ezlea .Llog,di
|
||
mov %r8d,%esi
|
||
push %rax
|
||
call *%rax
|
||
pop %rax
|
||
5: pop %rsi
|
||
pop %rdi
|
||
#endif /* DEBUGSYS */
|
||
pop %rdi
|
||
pop %rsi
|
||
pop %rbx
|
||
// 𝑠𝑙𝑖𝑑𝑒
|
||
.endfn _init_systemfive_magnums
|
||
#if SupportsSystemv()
|
||
_init_systemfive_pid:
|
||
ezlea __hostos,cx
|
||
mov (%rcx),%al
|
||
mov (%rdi),%eax
|
||
testb $_HOSTWINDOWS|_HOSTMETAL,(%rcx)
|
||
jnz 1f
|
||
mov __NR_getpid(%rip),%eax
|
||
syscall
|
||
1: stosq
|
||
.endfn _init_systemfive_pid
|
||
#endif
|
||
#if SupportsBsd() && !defined(TINY)
|
||
_init_systemfive_sigsys:
|
||
testb IsBsd() // BSDs will trap SIGSYS!
|
||
jz 1f // We want ENOSYS instead
|
||
push %rdi // XNU removed some calls
|
||
push %rsi // in past, so this makes
|
||
xor %eax,%eax // troubleshooting easier
|
||
push %rax // but it's non-essential
|
||
push %rax
|
||
push %rax
|
||
push %rax
|
||
push %rax
|
||
push $SIG_IGN // sigaction_meta size 48
|
||
mov __NR_sigaction(%rip),%eax // mag
|
||
mov SIGSYS(%rip),%edi // sig
|
||
mov %rsp,%rsi // new
|
||
xor %edx,%edx // old
|
||
mov $8,%r10d // for linux
|
||
xor %r8d,%r8d // for netbsd
|
||
syscall
|
||
add $6*8,%rsp
|
||
pop %rsi
|
||
pop %rdi
|
||
1: .endfn _init_systemfive_sigsys
|
||
#endif
|
||
_init_systemfive_done:
|
||
nop
|
||
.init.end 300,_init_systemfive,globl,hidden
|
||
|
||
#if SYSDEBUG
|
||
.rodata.str1.1
|
||
.Llog: .ascii STRACE_PROLOGUE
|
||
.ascii "bell system five system call support"
|
||
.asciz " %'u magnums loaded on %s\n"
|
||
.previous
|
||
#endif /* DEBUGSYS */
|