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https://github.com/jart/cosmopolitan.git
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155b378a39
The organization of the source files is now much more rational. Old experiments that didn't work out are now deleted. Naming of things like files is now more intuitive.
59 lines
2.9 KiB
C
59 lines
2.9 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2022 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/assert.h"
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#include "libc/calls/calls.h"
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#include "libc/calls/strace.internal.h"
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#include "libc/thread/tls.h"
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#include "libc/runtime/runtime.h"
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extern int __threadcalls_end[];
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extern int __threadcalls_start[];
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#pragma weak __threadcalls_start
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#pragma weak __threadcalls_end
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privileged void __enable_threads(void) {
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if (__threaded) return;
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STRACE("__enable_threads()");
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__morph_begin();
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/*
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* _NOPL("__threadcalls", func)
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*
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* The big ugly macro above is used by Cosmopolitan Libc to unser
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* locking primitive (e.g. flockfile, funlockfile) have zero impact on
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* performance and binary size when threads aren't actually in play.
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*
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* we have this
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*
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* 0f 1f 05 b1 19 00 00 nopl func(%rip)
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*
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* we're going to turn it into this
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*
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* 67 67 e8 b1 19 00 00 addr32 addr32 call func
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*
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* This is cheap and fast because the big ugly macro stored in the
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* binary the offsets of all the instructions we need to change.
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*/
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for (int *p = __threadcalls_start; p < __threadcalls_end; ++p) {
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_base[*p + 0] = 0x67;
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_base[*p + 1] = 0x67;
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_base[*p + 2] = 0xe8;
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}
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__morph_end();
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__threaded = gettid();
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}
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