kolibrios/programs/develop/libraries/newlib/crt/emutls.c

/* TLS emulation.
   Copyright (C) 2006, 2008, 2009 Free Software Foundation, Inc.
   Contributed by Jakub Jelinek <jakub@redhat.com>.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.

You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
<http://www.gnu.org/licenses/>.  */


#include <stdlib.h>
#include <malloc.h>
#include <errno.h>
#include <gthr.h>

void *tls_alloc(void);
void __mutex_lock(volatile int *val);


static inline void yield(void)
{
    __asm__ __volatile__(
    "int $0x40"
    ::"a"(68), "b"(1));
};

int __gthread_once (__gthread_once_t *once, void (*func) (void))
{
    if (once == NULL || func == NULL)
        return EINVAL;

    if (! once->done)
    {
        if(++once->started == 0)
        {
            (*func) ();
            once->done = 1;
        }
        else
        {
      /* Another thread is currently executing the code, so wait for it
         to finish; yield the CPU in the meantime.  If performance
         does become an issue, the solution is to use an Event that
         we wait on here (and set above), but that implies a place to
         create the event before this routine is called.  */
            while (! once->done)
                yield();
        }
    }
    return 0;
}


#define __GTHREAD_ONCE_INIT {0, -1}

typedef unsigned int word __attribute__((mode(word)));
typedef unsigned int pointer __attribute__((mode(pointer)));

struct __emutls_object
{
  word size;
  word align;
  union {
    pointer offset;
    void *ptr;
  } loc;
  void *templ;
};

struct __emutls_array
{
  pointer size;
  void **data[];
};

void *__emutls_get_address (struct __emutls_object *);
void __emutls_register_common (struct __emutls_object *, word, word, void *);

static __gthread_mutex_t emutls_mutex;
static __gthread_key_t   emutls_key;
static pointer           emutls_size;

static void emutls_destroy (void *ptr)
{
    struct __emutls_array *arr = ptr;
    pointer size = arr->size;
    pointer i;

    for (i = 0; i < size; ++i)
    {
        if (arr->data[i])
            free (arr->data[i][-1]);
    }
    free (ptr);
};

static void emutls_init (void)
{
    if (__gthread_key_create (&emutls_key, emutls_destroy) != 0)
        abort ();
}

static void *emutls_alloc (struct __emutls_object *obj)
{
    void *ptr;
    void *ret;

  /* We could use here posix_memalign if available and adjust
     emutls_destroy accordingly.  */
    if (obj->align <= sizeof (void *))
    {
        ptr = malloc (obj->size + sizeof (void *));
        if (ptr == NULL)
            abort ();
        ((void **) ptr)[0] = ptr;
        ret = ptr + sizeof (void *);
    }
    else
    {
        ptr = malloc (obj->size + sizeof (void *) + obj->align - 1);
        if (ptr == NULL)
            abort ();
        ret = (void *) (((pointer) (ptr + sizeof (void *) + obj->align - 1))
              & ~(pointer)(obj->align - 1));
        ((void **) ret)[-1] = ptr;
    }

    if (obj->templ)
        memcpy (ret, obj->templ, obj->size);
    else
        memset (ret, 0, obj->size);

    return ret;
}

void * __emutls_get_address (struct __emutls_object *obj)
{
    pointer offset = obj->loc.offset;

    if (__builtin_expect (offset == 0, 0))
    {
        static __gthread_once_t once = __GTHREAD_ONCE_INIT;
        __gthread_once (&once, emutls_init);
        __gthread_mutex_lock (&emutls_mutex);
        offset = obj->loc.offset;
        if (offset == 0)
        {
            offset = ++emutls_size;
            obj->loc.offset = offset;
        }
        __gthread_mutex_unlock (&emutls_mutex);
    }

    struct __emutls_array *arr = __gthread_getspecific (emutls_key);
    if (__builtin_expect (arr == NULL, 0))
    {
        pointer size = offset + 32;
        arr = calloc (size + 1, sizeof (void *));
        if (arr == NULL)
            abort ();
        arr->size = size;
        __gthread_setspecific (emutls_key, (void *) arr);
    }
    else if (__builtin_expect (offset > arr->size, 0))
    {
        pointer orig_size = arr->size;
        pointer size = orig_size * 2;
        if (offset > size)
            size = offset + 32;
        arr = realloc (arr, (size + 1) * sizeof (void *));
        if (arr == NULL)
            abort ();
        arr->size = size;
        memset (arr->data + orig_size, 0,
               (size - orig_size) * sizeof (void *));
        __gthread_setspecific (emutls_key, (void *) arr);
    }

    void *ret = arr->data[offset - 1];
    if (__builtin_expect (ret == NULL, 0))
    {
        ret = emutls_alloc (obj);
        arr->data[offset - 1] = ret;
    }
  return ret;
}


void __emutls_register_common (struct __emutls_object *obj,
              word size, word align, void *templ)
{
    if (obj->size < size)
    {
        obj->size = size;
        obj->templ = NULL;
    }
    if (obj->align < align)
        obj->align = align;
    if (templ && size == obj->size)
        obj->templ = templ;
}