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| | #define _GNU_SOURCE
#include "pthread_impl.h"
#include "stdio_impl.h"
#include "libc.h"
#include <sys/mman.h>
#include <string.h>
#include <threads.h>
void *__mmap(void *, size_t, int, int, int, off_t);
int __munmap(void *, size_t);
int __mprotect(void *, size_t, int);
void __thread_enable(void);
_Noreturn void __pthread_exit(void *);
void *__copy_tls(unsigned char *);
extern volatile size_t __pthread_tsd_size;
static void dummy_0()
{
}
weak_alias(dummy_0, __acquire_ptc);
weak_alias(dummy_0, __release_ptc);
static int start(void *p)
{
pthread_t self = p;
if (self->startlock[0]) {
__wait(self->startlock, 0, 1, 1);
if (self->startlock[0]) {
self->detached = 2;
pthread_exit(0);
}
__restore_sigs(self->sigmask);
}
if (self->unblock_cancel)
__syscall(SYS_rt_sigprocmask, SIG_UNBLOCK,
SIGPT_SET, 0, _NSIG/8);
pthread_exit(self->start(self->start_arg));
return 0;
}
#define ROUND(x) (((x)+PAGE_SIZE-1)&-PAGE_SIZE)
int pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attrp, void *(*entry)(void *), void *restrict arg)
{
int ret;
size_t size, guard = 0;
struct pthread *self, *new;
unsigned char *map = 0, *stack = 0, *tsd = 0, *stack_limit;
unsigned flags = CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND
| CLONE_THREAD | CLONE_SYSVSEM | CLONE_SETTLS
| CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID | CLONE_DETACHED;
int do_sched = 0;
pthread_attr_t attr = {0};
if (!libc.can_do_threads) return ENOSYS;
self = __pthread_self();
if (!libc.threaded) __thread_enable();
if (attrp) attr = *attrp;
__acquire_ptc();
if (attr._a_stackaddr) {
size_t need = libc.tls_size + __pthread_tsd_size;
size = attr._a_stacksize + DEFAULT_STACK_SIZE;
stack = (void *)(attr._a_stackaddr & -16);
stack_limit = (void *)(attr._a_stackaddr - size);
/* Use application-provided stack for TLS only when
* it does not take more than ~12% or 2k of the
* application's stack space. */
if (need < size/8 && need < 2048) {
tsd = stack - __pthread_tsd_size;
stack = tsd - libc.tls_size;
memset(stack, 0, need);
} else {
size = ROUND(need);
guard = 0;
}
} else {
guard = ROUND(DEFAULT_GUARD_SIZE + attr._a_guardsize);
size = guard + ROUND(DEFAULT_STACK_SIZE + attr._a_stacksize
+ libc.tls_size + __pthread_tsd_size);
}
if (!tsd) {
if (guard) {
map = __mmap(0, size, PROT_NONE, MAP_PRIVATE|MAP_ANON, -1, 0);
if (map == MAP_FAILED) goto fail_nomem;
if (__mprotect(map+guard, size-guard, PROT_READ|PROT_WRITE)) {
__munmap(map, size);
goto fail_nomem;
}
} else {
map = __mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);
if (map == MAP_FAILED) goto fail_nomem;
}
tsd = map + size - __pthread_tsd_size;
if (!stack) {
stack = tsd - libc.tls_size;
stack_limit = map + guard;
}
}
new = __copy_tls(tsd - libc.tls_size);
new->map_base = map;
new->map_size = size;
new->stack = stack;
new->stack_size = stack - stack_limit;
new->start = entry;
new->start_arg = arg;
new->self = new;
new->tsd = (void *)tsd;
new->locale = &libc.global_locale;
if (attr._a_detach) {
new->detached = 1;
flags -= CLONE_CHILD_CLEARTID;
}
if (attr._a_sched) {
do_sched = new->startlock[0] = 1;
__block_app_sigs(new->sigmask);
}
new->unblock_cancel = self->cancel;
new->canary = self->canary;
a_inc(&libc.threads_minus_1);
ret = __clone(start, stack, flags, new, &new->tid, TP_ADJ(new), &new->tid);
__release_ptc();
if (do_sched) {
__restore_sigs(new->sigmask);
}
if (ret < 0) {
a_dec(&libc.threads_minus_1);
if (map) __munmap(map, size);
return EAGAIN;
}
if (do_sched) {
ret = __syscall(SYS_sched_setscheduler, new->tid,
attr._a_policy, &attr._a_prio);
a_store(new->startlock, ret<0 ? 2 : 0);
__wake(new->startlock, 1, 1);
if (ret < 0) return -ret;
}
*res = new;
return 0;
fail_nomem:
__release_ptc();
return EAGAIN;
}
|