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cosmopolitan/libc/thread/pthread_create.c
Justine Tunney e961385e55
Put more thought into i/o polyfills 
wait4() is now solid enough to run `make -j100` on Windows. You can now
use MSG_DONTWAIT on Windows. There was a handle leak in accept() that's
been fixed. Our WIN32 overlapped i/o code has been simplified. Priority
class now inherits into subprocesses, so the verynice command will work
and the signal mask will now be inherited by execve() and posix_spawn()
2023-11-07 18:32:35 -08:00

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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2022 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/calls/calls.h"
#include "libc/calls/struct/sigset.h"
#include "libc/calls/struct/sigset.internal.h"
#include "libc/calls/syscall-sysv.internal.h"
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/fmt/itoa.h"
#include "libc/intrin/asan.internal.h"
#include "libc/intrin/bits.h"
#include "libc/intrin/bsr.h"
#include "libc/intrin/describeflags.internal.h"
#include "libc/intrin/dll.h"
#include "libc/intrin/strace.internal.h"
#include "libc/intrin/weaken.h"
#include "libc/log/internal.h"
#include "libc/macros.internal.h"
#include "libc/mem/alloca.h"
#include "libc/mem/mem.h"
#include "libc/nexgen32e/crc32.h"
#include "libc/nt/enum/memflags.h"
#include "libc/nt/enum/pageflags.h"
#include "libc/nt/memory.h"
#include "libc/nt/runtime.h"
#include "libc/nt/synchronization.h"
#include "libc/runtime/runtime.h"
#include "libc/runtime/stack.h"
#include "libc/runtime/syslib.internal.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/auxv.h"
#include "libc/sysv/consts/clone.h"
#include "libc/sysv/consts/map.h"
#include "libc/sysv/consts/prot.h"
#include "libc/sysv/consts/sig.h"
#include "libc/sysv/consts/ss.h"
#include "libc/thread/posixthread.internal.h"
#include "libc/thread/thread.h"
#include "libc/thread/tls.h"
__static_yoink("nsync_mu_lock");
__static_yoink("nsync_mu_unlock");
__static_yoink("nsync_mu_trylock");
__static_yoink("nsync_mu_rlock");
__static_yoink("nsync_mu_runlock");
__static_yoink("_pthread_atfork");
#define MAP_ANON_OPENBSD 0x1000
#define MAP_STACK_OPENBSD 0x4000
void _pthread_free(struct PosixThread *pt, bool isfork) {
unassert(dll_is_alone(&pt->list) && &pt->list != _pthread_list);
if (pt->pt_flags & PT_STATIC) return;
if (pt->pt_flags & PT_OWNSTACK) {
unassert(!munmap(pt->pt_attr.__stackaddr, pt->pt_attr.__stacksize));
}
if (!isfork) {
if (IsWindows()) {
if (pt->tib->tib_syshand) {
unassert(CloseHandle(pt->tib->tib_syshand));
}
} else if (IsXnuSilicon()) {
if (pt->tib->tib_syshand) {
__syslib->__pthread_join(pt->tib->tib_syshand, 0);
}
}
}
free(pt->pt_tls);
free(pt);
}
void _pthread_decimate(void) {
struct Dll *e;
struct PosixThread *pt;
enum PosixThreadStatus status;
StartOver:
_pthread_lock();
for (e = dll_last(_pthread_list); e; e = dll_prev(_pthread_list, e)) {
pt = POSIXTHREAD_CONTAINER(e);
status = atomic_load_explicit(&pt->pt_status, memory_order_acquire);
if (status != kPosixThreadZombie) break;
if (!atomic_load_explicit(&pt->tib->tib_tid, memory_order_acquire)) {
dll_remove(&_pthread_list, e);
_pthread_unlock();
_pthread_unref(pt);
goto StartOver;
}
}
_pthread_unlock();
}
static int PosixThread(void *arg, int tid) {
void *rc;
struct PosixThread *pt = arg;
if (pt->pt_attr.__inheritsched == PTHREAD_EXPLICIT_SCHED) {
unassert(_weaken(_pthread_reschedule));
_weaken(_pthread_reschedule)(pt); // yoinked by attribute builder
}
// set long jump handler so pthread_exit can bring control back here
if (!setjmp(pt->pt_exiter)) {
if (IsWindows()) {
atomic_store_explicit(&__get_tls()->tib_sigmask, pt->pt_attr.__sigmask,
memory_order_release);
} else {
sys_sigprocmask(SIG_SETMASK, &pt->pt_attr.__sigmask, 0);
}
rc = pt->pt_start(pt->pt_arg);
// ensure pthread_cleanup_pop(), and pthread_exit() popped cleanup
unassert(!pt->pt_cleanup);
// calling pthread_exit() will either jump back here, or call exit
pthread_exit(rc);
}
// avoid signal handler being triggered after we trash our own stack
__sig_block();
// return to clone polyfill which clears tid, wakes futex, and exits
return 0;
}
static int FixupCustomStackOnOpenbsd(pthread_attr_t *attr) {
// OpenBSD: Only permits RSP to occupy memory that's been explicitly
// defined as stack memory. We need to squeeze the provided interval
// in order to successfully call mmap(), which will return EINVAL if
// these calculations should overflow.
size_t n;
uintptr_t x, y;
int e, rc, pagesz;
pagesz = getauxval(AT_PAGESZ);
n = attr->__stacksize;
x = (uintptr_t)attr->__stackaddr;
y = ROUNDUP(x, pagesz);
n -= y - x;
n = ROUNDDOWN(n, pagesz);
e = errno;
if (__sys_mmap((void *)y, n, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_FIXED | MAP_ANON_OPENBSD | MAP_STACK_OPENBSD,
-1, 0, 0) == (void *)y) {
attr->__stackaddr = (void *)y;
attr->__stacksize = n;
return 0;
} else {
rc = errno;
errno = e;
if (rc == EOVERFLOW) {
rc = EINVAL;
}
return rc;
}
}
static errno_t pthread_create_impl(pthread_t *thread,
const pthread_attr_t *attr,
void *(*start_routine)(void *), void *arg,
sigset_t oldsigs) {
int rc, e = errno;
struct PosixThread *pt;
// create posix thread object
if (!(pt = calloc(1, sizeof(struct PosixThread)))) {
errno = e;
return EAGAIN;
}
pt->pt_start = start_routine;
pt->pt_arg = arg;
// create thread local storage memory
if (!(pt->pt_tls = _mktls(&pt->tib))) {
free(pt);
errno = e;
return EAGAIN;
}
// setup attributes
if (attr) {
pt->pt_attr = *attr;
attr = 0;
} else {
pthread_attr_init(&pt->pt_attr);
}
// setup stack
if (pt->pt_attr.__stackaddr) {
// caller supplied their own stack
// assume they know what they're doing as much as possible
if (IsOpenbsd()) {
if ((rc = FixupCustomStackOnOpenbsd(&pt->pt_attr))) {
_pthread_free(pt, false);
return rc;
}
}
} else {
// cosmo is managing the stack
// 1. in mono repo optimize for tiniest stack possible
// 2. in public world optimize to *work* regardless of memory
int granularity = FRAMESIZE;
int pagesize = getauxval(AT_PAGESZ);
pt->pt_attr.__guardsize = ROUNDUP(pt->pt_attr.__guardsize, pagesize);
pt->pt_attr.__stacksize = ROUNDUP(pt->pt_attr.__stacksize, granularity);
if (pt->pt_attr.__guardsize + pagesize > pt->pt_attr.__stacksize) {
_pthread_free(pt, false);
return EINVAL;
}
if (pt->pt_attr.__guardsize == pagesize) {
pt->pt_attr.__stackaddr =
mmap(0, pt->pt_attr.__stacksize, PROT_READ | PROT_WRITE,
MAP_STACK | MAP_ANONYMOUS, -1, 0);
} else {
pt->pt_attr.__stackaddr =
mmap(0, pt->pt_attr.__stacksize, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (pt->pt_attr.__stackaddr != MAP_FAILED) {
if (IsOpenbsd() &&
__sys_mmap(
pt->pt_attr.__stackaddr, pt->pt_attr.__stacksize,
PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_FIXED | MAP_ANON_OPENBSD | MAP_STACK_OPENBSD,
-1, 0, 0) != pt->pt_attr.__stackaddr) {
notpossible;
}
if (pt->pt_attr.__guardsize) {
if (!IsWindows()) {
if (mprotect(pt->pt_attr.__stackaddr, pt->pt_attr.__guardsize,
PROT_NONE)) {
notpossible;
}
} else {
uint32_t oldattr;
if (!VirtualProtect(pt->pt_attr.__stackaddr,
pt->pt_attr.__guardsize,
kNtPageReadwrite | kNtPageGuard, &oldattr)) {
notpossible;
}
}
}
}
}
if (!pt->pt_attr.__stackaddr || pt->pt_attr.__stackaddr == MAP_FAILED) {
rc = errno;
_pthread_free(pt, false);
errno = e;
if (rc == EINVAL || rc == EOVERFLOW) {
return EINVAL;
} else {
return EAGAIN;
}
}
pt->pt_flags |= PT_OWNSTACK;
if (IsAsan() && !IsWindows() && pt->pt_attr.__guardsize) {
__asan_poison(pt->pt_attr.__stackaddr, pt->pt_attr.__guardsize,
kAsanStackOverflow);
}
}
// set initial status
pt->tib->tib_pthread = (pthread_t)pt;
atomic_store_explicit(&pt->tib->tib_sigmask, -1, memory_order_relaxed);
if (!pt->pt_attr.__havesigmask) {
pt->pt_attr.__havesigmask = true;
pt->pt_attr.__sigmask = oldsigs;
}
switch (pt->pt_attr.__detachstate) {
case PTHREAD_CREATE_JOINABLE:
atomic_store_explicit(&pt->pt_status, kPosixThreadJoinable,
memory_order_relaxed);
break;
case PTHREAD_CREATE_DETACHED:
atomic_store_explicit(&pt->pt_status, kPosixThreadDetached,
memory_order_relaxed);
break;
default:
_pthread_free(pt, false);
return EINVAL;
}
// add thread to global list
// we add it to the beginning since zombies go at the end
dll_init(&pt->list);
_pthread_lock();
dll_make_first(&_pthread_list, &pt->list);
_pthread_unlock();
// launch PosixThread(pt) in new thread
if ((rc = clone(PosixThread, pt->pt_attr.__stackaddr,
pt->pt_attr.__stacksize - (IsOpenbsd() ? 16 : 0),
CLONE_VM | CLONE_THREAD | CLONE_FS | CLONE_FILES |
CLONE_SIGHAND | CLONE_SYSVSEM | CLONE_SETTLS |
CLONE_PARENT_SETTID | CLONE_CHILD_SETTID |
CLONE_CHILD_CLEARTID,
pt, &pt->ptid, __adj_tls(pt->tib), &pt->tib->tib_tid))) {
_pthread_lock();
dll_remove(&_pthread_list, &pt->list);
_pthread_unlock();
_pthread_free(pt, false);
return rc;
}
*thread = (pthread_t)pt;
return 0;
}
static const char *DescribeHandle(char buf[12], errno_t err, pthread_t *th) {
if (err) return "n/a";
if (!th) return "NULL";
FormatInt32(buf, _pthread_tid((struct PosixThread *)*th));
return buf;
}
/**
* Creates thread, e.g.
*
* void *worker(void *arg) {
* fputs(arg, stdout);
* return "there\n";
* }
*
* int main() {
* void *result;
* pthread_t id;
* pthread_create(&id, 0, worker, "hi ");
* pthread_join(id, &result);
* fputs(result, stdout);
* }
*
* Here's the OSI model of threads in Cosmopolitan:
*
* ┌──────────────────┐
* │ pthread_create() │ - Standard
* └─────────┬────────┘ Abstraction
* ┌─────────┴────────┐
* │ clone() │ - Polyfill
* └─────────┬────────┘
* ┌────────┬──┴┬─┬─┬─────────┐ - Kernel
* ┌─────┴─────┐ │ │ │┌┴──────┐ │ Interfaces
* │ sys_clone │ │ │ ││ tfork │ ┌┴─────────────┐
* └───────────┘ │ │ │└───────┘ │ CreateThread │
* ┌───────────────┴──┐│┌┴────────┐ └──────────────┘
* │ bsdthread_create │││ thr_new │
* └──────────────────┘│└─────────┘
* ┌───────┴──────┐
* │ _lwp_create │
* └──────────────┘
*
* @param thread if non-null is used to output the thread id
* upon successful completion
* @param attr points to launch configuration, or may be null
* to use sensible defaults; it must be initialized using
* pthread_attr_init()
* @param start_routine is your thread's callback function
* @param arg is an arbitrary value passed to `start_routine`
* @return 0 on success, or errno on error
* @raise EAGAIN if resources to create thread weren't available
* @raise EINVAL if `attr` was supplied and had unnaceptable data
* @raise EPERM if scheduling policy was requested and user account
* isn't authorized to use it
* @returnserrno
*/
errno_t pthread_create(pthread_t *thread, const pthread_attr_t *attr,
void *(*start_routine)(void *), void *arg) {
errno_t err;
_pthread_decimate();
BLOCK_SIGNALS;
err = pthread_create_impl(thread, attr, start_routine, arg, _SigMask);
ALLOW_SIGNALS;
STRACE("pthread_create([%s], %p, %t, %p) → %s",
DescribeHandle(alloca(12), err, thread), attr, start_routine, arg,
DescribeErrno(err));
return err;
}
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