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/* $OpenBSD: tib.c,v 1.2 2017/12/01 23:30:05 guenther Exp $ */
/*
* Copyright (c) 2016 Philip Guenther <guenther@openbsd.org>
*
* Permission to use, copy, modify, and 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 <tib.h>
#ifndef PIC
# include <stdlib.h> /* posix_memalign and free */
#endif
#define ELF_ROUND(x,malign) (((x) + (malign)-1) & ~((malign)-1))
/*
* The functions here are weak so that the ld.so versions are used
* in dynamic links, whether or not libc is static
*/
void *_dl_allocate_tib(size_t _extra) __attribute__((weak));
void _dl_free_tib(void *_tib, size_t _extra) __attribute__((weak));
/*
* Allocate a TIB for passing to __tfork for a new thread. 'extra'
* is the amount of space to allocate on the side of the TIB opposite
* of the TLS data: before the TIB for variant 1 and after the TIB
* for variant 2. If non-zero, tib_thread is set to point to that area.
*/
void *
_dl_allocate_tib(size_t extra)
{
#ifdef PIC
return NULL; /* overriden by ld.so */
#else
void *base;
char *thread;
# if TLS_VARIANT == 1
/* round up the extra size to align the TIB and TLS data after it */
extra = (extra <= _static_tls_align_offset) ? 0 :
ELF_ROUND(extra - _static_tls_align_offset, _static_tls_align);
if (posix_memalign(&base, _static_tls_align, extra +
_static_tls_align_offset + sizeof(struct tib) +
_static_tls_size) != 0)
return NULL;
thread = base;
base = (char *)base + extra;
# elif TLS_VARIANT == 2
/* round up the TIB size to align the extra area after it */
if (posix_memalign(&base, _static_tls_align,
_static_tls_align_offset + _static_tls_size +
ELF_ROUND(sizeof(struct tib), TIB_EXTRA_ALIGN) + extra) != 0)
return NULL;
thread = (char *)base + _static_tls_align_offset + _static_tls_size +
ELF_ROUND(sizeof(struct tib), TIB_EXTRA_ALIGN);
# endif
return _static_tls_init(base, thread);
#endif /* !PIC */
}
void
_dl_free_tib(void *tib, size_t extra)
{
#ifndef PIC
size_t tib_offset;
# if TLS_VARIANT == 1
tib_offset = (extra <= _static_tls_align_offset) ? 0 :
ELF_ROUND(extra - _static_tls_align_offset, _static_tls_align);
# elif TLS_VARIANT == 2
tib_offset = _static_tls_size;
# endif
tib_offset += _static_tls_align_offset;
free((char *)tib - tib_offset);
#endif /* !PIC */
}
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