source: mainline/uspace/lib/c/generic/tls.c@ 48bd6f4

/*
 * Copyright (c) 2006 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup libc
 * @{
 */
/** @file
 *
 * Support for thread-local storage, as described in:
 *      Drepper U.: ELF Handling For Thread-Local Storage, 2005
 *
 * Only static model is supported.
 */ 

#include <tls.h>
#include <malloc.h>
#include <str.h>
#include <align.h>
#include <unistd.h>

/** Create TLS (Thread Local Storage) data structures.
 *
 * The code requires, that sections .tdata and .tbss are adjacent. It may be
 * changed in the future.
 *
 * @return Pointer to TCB.
 */
tcb_t *tls_make(void)
{
        void *data;
        tcb_t *tcb;
        size_t tls_size = &_tbss_end - &_tdata_start;
        
        tcb = tls_alloc_arch(&data, tls_size);
        if (!tcb)
                return NULL;
        
        /*
         * Copy thread local data from the initialization image.
         */
        memcpy(data, &_tdata_start, &_tdata_end - &_tdata_start);
        /*
         * Zero out the thread local uninitialized data.
         */
        memset(data + (&_tbss_start - &_tdata_start), 0,
            &_tbss_end - &_tbss_start);

        return tcb;
}

void tls_free(tcb_t *tcb)
{
        size_t tls_size = &_tbss_end - &_tdata_start;
        tls_free_arch(tcb, tls_size);
}

#ifdef CONFIG_TLS_VARIANT_1
/** Allocate TLS variant 1 data structures.
 *
 * @param data          Start of TLS section. This is an output argument.
 * @param size          Size of tdata + tbss section.
 * @return              Pointer to tcb_t structure.
 */
tcb_t *tls_alloc_variant_1(void **data, size_t size)
{
        tcb_t *result;

        result = malloc(sizeof(tcb_t) + size);
        if (!result)
                return NULL;
        *data = ((void *)result) + sizeof(tcb_t);

        return result;
}

/** Free TLS variant I data structures.
 *
 * @param tcb           Pointer to TCB structure.
 * @param size          This argument is ignored.
 */
void tls_free_variant_1(tcb_t *tcb, size_t size)
{
        free(tcb);
}
#endif

#ifdef CONFIG_TLS_VARIANT_2
/** Allocate TLS variant II data structures.
 *
 * @param data          Pointer to pointer to thread local data. This is
 *                      actually an output argument.
 * @param size          Size of thread local data.
 * @return              Pointer to TCB structure.
 */
tcb_t * tls_alloc_variant_2(void **data, size_t size)
{
        tcb_t *tcb;
        
        size = ALIGN_UP(size, &_tls_alignment);
        *data = memalign((uintptr_t) &_tls_alignment, sizeof(tcb_t) + size);
        if (!*data)
                return NULL;
        tcb = (tcb_t *) (*data + size);
        tcb->self = tcb;

        return tcb;
}

/** Free TLS variant II data structures.
 *
 * @param tcb           Pointer to TCB structure.
 * @param size          Size of thread local data.
 */
void tls_free_variant_2(tcb_t *tcb, size_t size)
{
        size = ALIGN_UP(size, &_tls_alignment);
        void *start = ((void *) tcb) - size;
        free(start);
}
#endif

/** @}
 */