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#include "stddef.h"
#include "sys/cdefs.h"
#include <__thread.h>
#include <libc.h>
#include <sched.h>
#include <stdint.h>
#include <stdio.h>
#include <sys/mman.h>
#include <syscall.h>
#include <threads.h>
struct thread_start {
struct __thread_self *self;
thrd_start_t func;
void *arg;
};
static long __thread_start(void *arg)
{
struct thread_start *ts = (struct thread_start *)arg;
syscall(set_tid_address, &ts->self->tid);
int r = ts->func(ts->arg);
thrd_exit(r);
__builtin_unreachable();
}
int thrd_create(thrd_t *thr, thrd_start_t func, void *arg)
{
struct thread_start *ts;
if ((void *)thr == NULL || func == NULL)
return thrd_error;
/* Ensure callers never observe an uninitialized thread handle on failure. */
*thr = NULL;
void *map;
size_t size = THREAD_GUARD_SIZE + THREAD_STACK_SIZE + __libc.tls.size + sizeof(struct __thread_self);
map = mmap(NULL, size, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (__predict_false(map == MAP_FAILED))
return thrd_nomem;
if (__predict_false(mprotect((unsigned char *)map + THREAD_GUARD_SIZE, size - THREAD_GUARD_SIZE,
PROT_READ | PROT_WRITE) < 0)) {
munmap(map, size);
return thrd_error;
}
unsigned char *base = (unsigned char *)map;
/* Place TCB at the very end of the mapping. */
struct __thread_self *tcb = (struct __thread_self *)(base + size - sizeof(struct __thread_self));
/* Place TLS immediately below the TCB, aligned down. */
unsigned char *tls_end = (unsigned char *)tcb;
size_t tls_align = __libc.tls.align;
if (tls_align == 0 || (tls_align & (tls_align - 1)) != 0)
tls_align = sizeof(void *);
if (tls_align < sizeof(void *))
tls_align = sizeof(void *);
unsigned char *tls_start =
(unsigned char *)(((uintptr_t)(tls_end - __libc.tls.size)) & ~((uintptr_t)tls_align - 1));
__libc_tls_copy(tls_start);
/* Build initial stack just below TLS. */
unsigned char *stack_top = tls_start;
ts = (struct thread_start *)(stack_top - sizeof(struct thread_start));
stack_top -= sizeof(struct thread_start);
ts->self = tcb;
ts->func = func;
ts->arg = arg;
stack_top = (unsigned char *)((uintptr_t)stack_top & ~15UL);
tcb->self = tcb;
tcb->map_base = map;
tcb->map_size = size;
tcb->errno_v = 0;
tcb->dtv = 0;
tcb->state = THREAD_STATE_JOINABLE;
unsigned long flags = CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND | CLONE_THREAD | CLONE_SYSVSEM |
CLONE_SETTLS | CLONE_PARENT_SETTID | CLONE_CHILD_SETTID | CLONE_CHILD_CLEARTID;
#if defined(__x86_64__)
long tid = __clone(__thread_start, ts, flags, stack_top, &tcb->tid, tcb, &tcb->tid);
#endif
if (__predict_false(tid < 0)) {
munmap(map, size);
return thrd_error;
}
#if !defined(__x86_64__)
if (tid == 0) {
__thread_start(ts);
__builtin_unreachable();
}
#endif
tcb->tid = tid;
*thr = tcb;
return thrd_success;
}
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