mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-02-01 03:53:33 +00:00
4a6fd3d910
- fix rare thread exit race condition on openbsd - pthread_getattr_np() now supplies detached status - child threads may now pthread_join() the main thread - introduce sigandset(), sigorset(), and sigisemptyset() - introduce pthread_cleanup_push() and pthread_cleanup_pop()
312 lines
11 KiB
C
312 lines
11 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/sched-sysv.internal.h"
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#include "libc/calls/struct/sigaltstack.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/errno.h"
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#include "libc/intrin/asan.internal.h"
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#include "libc/intrin/atomic.h"
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#include "libc/intrin/bits.h"
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#include "libc/intrin/kprintf.h"
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#include "libc/intrin/weaken.h"
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#include "libc/log/internal.h"
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#include "libc/macros.internal.h"
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#include "libc/mem/mem.h"
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#include "libc/nexgen32e/gc.internal.h"
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#include "libc/runtime/clone.internal.h"
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#include "libc/runtime/runtime.h"
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#include "libc/runtime/stack.h"
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#include "libc/sysv/consts/clone.h"
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#include "libc/sysv/consts/map.h"
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#include "libc/sysv/consts/prot.h"
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#include "libc/sysv/consts/ss.h"
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#include "libc/sysv/errfuns.h"
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#include "libc/thread/posixthread.internal.h"
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#include "libc/thread/spawn.h"
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#include "libc/thread/thread.h"
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#include "libc/thread/tls.h"
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#include "libc/thread/wait0.internal.h"
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STATIC_YOINK("nsync_mu_lock");
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STATIC_YOINK("nsync_mu_unlock");
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#define MAP_ANON_OPENBSD 0x1000
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#define MAP_STACK_OPENBSD 0x4000
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void _pthread_wait(struct PosixThread *pt) {
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_wait0(&pt->tib->tib_tid);
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}
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void _pthread_free(struct PosixThread *pt) {
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if (pt->flags & PT_MAINTHREAD) return;
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free(pt->tls);
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if ((pt->flags & PT_OWNSTACK) && //
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pt->attr.__stackaddr && //
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pt->attr.__stackaddr != MAP_FAILED) {
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if (munmap(pt->attr.__stackaddr, pt->attr.__stacksize)) {
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notpossible;
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}
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}
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if (pt->altstack) {
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free(pt->altstack);
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}
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free(pt);
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}
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static int PosixThread(void *arg, int tid) {
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struct PosixThread *pt = arg;
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enum PosixThreadStatus status;
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struct sigaltstack ss;
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if (pt->altstack) {
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ss.ss_flags = 0;
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ss.ss_size = SIGSTKSZ;
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ss.ss_sp = pt->altstack;
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if (sigaltstack(&ss, 0)) {
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notpossible;
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}
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}
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if (pt->attr.__inheritsched == PTHREAD_EXPLICIT_SCHED) {
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_pthread_reschedule(pt);
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}
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// set long jump handler so pthread_exit can bring control back here
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if (!setjmp(pt->exiter)) {
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__get_tls()->tib_pthread = (pthread_t)pt;
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pt->rc = pt->start_routine(pt->arg);
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// ensure pthread_cleanup_pop(), and pthread_exit() popped cleanup
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_npassert(!pt->cleanup);
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}
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// run garbage collector, call key destructors, and set change state
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_pthread_cleanup(pt);
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// return to clone polyfill which clears tid, wakes futex, and exits
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return 0;
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}
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static int FixupCustomStackOnOpenbsd(pthread_attr_t *attr) {
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// OpenBSD: Only permits RSP to occupy memory that's been explicitly
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// defined as stack memory. We need to squeeze the provided interval
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// in order to successfully call mmap(), which will return EINVAL if
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// these calculations should overflow.
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size_t n;
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int e, rc;
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uintptr_t x, y;
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n = attr->__stacksize;
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x = (uintptr_t)attr->__stackaddr;
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y = ROUNDUP(x, PAGESIZE);
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n -= y - x;
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n = ROUNDDOWN(n, PAGESIZE);
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e = errno;
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if (__sys_mmap((void *)y, n, PROT_READ | PROT_WRITE,
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MAP_PRIVATE | MAP_FIXED | MAP_ANON_OPENBSD | MAP_STACK_OPENBSD,
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-1, 0, 0) == (void *)y) {
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attr->__stackaddr = (void *)y;
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attr->__stacksize = n;
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return 0;
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} else {
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rc = errno;
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errno = e;
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if (rc == EOVERFLOW) {
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rc = EINVAL;
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}
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return rc;
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}
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}
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/**
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* Creates thread, e.g.
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*
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* void *worker(void *arg) {
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* fputs(arg, stdout);
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* return "there\n";
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* }
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*
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* int main() {
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* void *result;
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* pthread_t id;
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* pthread_create(&id, 0, worker, "hi ");
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* pthread_join(id, &result);
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* fputs(result, stdout);
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* }
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*
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* Here's the OSI model of threads in Cosmopolitan:
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*
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* ┌──────────────────┐
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* │ pthread_create() │ - Standard
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* └─────────┬────────┘ Abstraction
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* ┌─────────┴────────┐
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* │ clone() │ - Polyfill
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* └─────────┬────────┘
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* ┌────────┬──┴┬─┬─┬─────────┐ - Kernel
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* ┌─────┴─────┐ │ │ │┌┴──────┐ │ Interfaces
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* │ sys_clone │ │ │ ││ tfork │ ┌┴─────────────┐
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* └───────────┘ │ │ │└───────┘ │ CreateThread │
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* ┌───────────────┴──┐│┌┴────────┐ └──────────────┘
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* │ bsdthread_create │││ thr_new │
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* └──────────────────┘│└─────────┘
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* ┌───────┴──────┐
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* │ _lwp_create │
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* └──────────────┘
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*
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* @param thread if non-null is used to output the thread id
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* upon successful completion
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* @param attr points to launch configuration, or may be null
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* to use sensible defaults; it must be initialized using
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* pthread_attr_init()
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* @param start_routine is your thread's callback function
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* @param arg is an arbitrary value passed to `start_routine`
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* @return 0 on success, or errno on error
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* @raise EAGAIN if resources to create thread weren't available
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* @raise EINVAL if `attr` was supplied and had unnaceptable data
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* @raise EPERM if scheduling policy was requested and user account
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* isn't authorized to use it
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* @returnserrno
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* @threadsafe
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*/
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errno_t pthread_create(pthread_t *thread, const pthread_attr_t *attr,
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void *(*start_routine)(void *), void *arg) {
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int rc, e = errno;
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struct PosixThread *pt;
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__require_tls();
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_pthread_zombies_decimate();
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// create posix thread object
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if (!(pt = calloc(1, sizeof(struct PosixThread)))) {
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errno = e;
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return EAGAIN;
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}
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pt->start_routine = start_routine;
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pt->arg = arg;
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// create thread local storage memory
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if (!(pt->tls = _mktls(&pt->tib))) {
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free(pt);
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errno = e;
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return EAGAIN;
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}
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// setup attributes
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if (attr) {
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pt->attr = *attr;
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attr = 0;
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} else {
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pthread_attr_init(&pt->attr);
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}
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// setup stack
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if (pt->attr.__stackaddr) {
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// caller supplied their own stack
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// assume they know what they're doing as much as possible
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if (IsOpenbsd()) {
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if ((rc = FixupCustomStackOnOpenbsd(&pt->attr))) {
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_pthread_free(pt);
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return rc;
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}
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}
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} else {
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// cosmo is managing the stack
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// 1. in mono repo optimize for tiniest stack possible
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// 2. in public world optimize to *work* regardless of memory
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pt->flags = PT_OWNSTACK;
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pt->attr.__stacksize = MAX(pt->attr.__stacksize, GetStackSize());
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pt->attr.__stacksize = _roundup2pow(pt->attr.__stacksize);
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pt->attr.__guardsize = ROUNDUP(pt->attr.__guardsize, PAGESIZE);
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if (pt->attr.__guardsize + PAGESIZE >= pt->attr.__stacksize) {
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_pthread_free(pt);
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return EINVAL;
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}
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if (pt->attr.__guardsize == PAGESIZE) {
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// user is wisely using smaller stacks with default guard size
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pt->attr.__stackaddr =
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mmap(0, pt->attr.__stacksize, PROT_READ | PROT_WRITE,
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MAP_STACK | MAP_ANONYMOUS, -1, 0);
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} else {
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// user is tuning things, performance may suffer
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pt->attr.__stackaddr =
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mmap(0, pt->attr.__stacksize, PROT_READ | PROT_WRITE,
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MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
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if (pt->attr.__stackaddr != MAP_FAILED) {
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if (IsOpenbsd() &&
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__sys_mmap(
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pt->attr.__stackaddr, pt->attr.__stacksize,
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PROT_READ | PROT_WRITE,
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MAP_PRIVATE | MAP_FIXED | MAP_ANON_OPENBSD | MAP_STACK_OPENBSD,
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-1, 0, 0) != pt->attr.__stackaddr) {
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notpossible;
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}
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if (pt->attr.__guardsize && !IsWindows() &&
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mprotect(pt->attr.__stackaddr, pt->attr.__guardsize, PROT_NONE)) {
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notpossible;
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}
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}
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}
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if (pt->attr.__stackaddr == MAP_FAILED) {
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rc = errno;
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_pthread_free(pt);
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errno = e;
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if (rc == EINVAL || rc == EOVERFLOW) {
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return EINVAL;
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} else {
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return EAGAIN;
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}
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}
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if (IsAsan() && pt->attr.__guardsize) {
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__asan_poison(pt->attr.__stackaddr, pt->attr.__guardsize,
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kAsanStackOverflow);
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}
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}
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// setup signal handler stack
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if (_wantcrashreports && !IsWindows()) {
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pt->altstack = malloc(SIGSTKSZ);
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}
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// set initial status
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switch (pt->attr.__detachstate) {
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case PTHREAD_CREATE_JOINABLE:
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pt->status = kPosixThreadJoinable;
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break;
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case PTHREAD_CREATE_DETACHED:
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pt->status = kPosixThreadDetached;
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_pthread_zombies_add(pt);
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break;
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default:
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_pthread_free(pt);
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return EINVAL;
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}
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// launch PosixThread(pt) in new thread
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if (clone(PosixThread, pt->attr.__stackaddr,
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pt->attr.__stacksize - (IsOpenbsd() ? 16 : 0),
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CLONE_VM | CLONE_THREAD | CLONE_FS | CLONE_FILES | CLONE_SIGHAND |
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CLONE_SETTLS | CLONE_PARENT_SETTID | CLONE_CHILD_SETTID |
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CLONE_CHILD_CLEARTID,
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pt, &pt->tid, pt->tib, &pt->tib->tib_tid) == -1) {
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rc = errno;
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_pthread_free(pt);
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errno = e;
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return rc;
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}
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if (thread) {
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*thread = (pthread_t)pt;
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}
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return 0;
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}
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