mirror of
https://github.com/jart/cosmopolitan.git
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fbc053e018
- Introduce __assert_disable global - Improve strsignal() thread safety - Make system call tracing thread safe - Fix SO_RCVTIMEO / SO_SNDTIMEO on Windows - Refactor DescribeFoo() functions into one place - Fix fork() on Windows when TLS and MAP_STACK exist - Round upwards in setsockopt(SO_RCVTIMEO) on Windows - Disable futexes on OpenBSD which seem extremely broken - Implement a better kludge for monotonic time on Windows
60 lines
3.1 KiB
C
60 lines
3.1 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 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/assert.h"
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#include "libc/calls/calls.h"
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#include "libc/calls/syscall-sysv.internal.h"
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#include "libc/dce.h"
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#include "libc/nexgen32e/gettls.h"
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#include "libc/nexgen32e/threaded.h"
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/**
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* Returns current thread id.
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*
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* On Linux, and Linux only, this is guaranteed to be equal to getpid()
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* if this is the main thread. On NetBSD, gettid() for the main thread
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* is always 1.
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*
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* This function issues a system call. That stops being the case as soon
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* as __install_tls() is called. That'll happen automatically, when you
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* call clone() and provide the TLS parameter. We assume that when a TLS
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* block exists, then
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*
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* *(int *)(__get_tls() + 0x38)
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*
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* will contain the thread id. Therefore when issuing clone() calls, the
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* `CLONE_CHILD_SETTID` and `CLONE_CHILD_CLEARTID` flags should use that
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* index as its `ctid` memory.
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*
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* gettid (single threaded) l: 126𝑐 41𝑛𝑠
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* gettid (tls enabled) l: 2𝑐 1𝑛𝑠
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*
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* The TLS convention is important for reentrant lock performance.
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*
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* @return thread id greater than zero or -1 w/ errno
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* @asyncsignalsafe
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* @threadsafe
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*/
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privileged int gettid(void) {
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int tid;
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if (__tls_enabled) {
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tid = *(int *)(__get_tls_inline() + 0x38);
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if (tid > 0) return tid;
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}
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return sys_gettid();
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}
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