gcc/libgcc/emutls.c
2024-01-03 12:19:35 +01:00

225 lines
5.8 KiB
C

/* TLS emulation.
Copyright (C) 2006-2024 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 "tconfig.h"
#include "tsystem.h"
#include "coretypes.h"
#include "tm.h"
#include "libgcc_tm.h"
#include "gthr.h"
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[];
};
/* EMUTLS_ATTR is provided to allow targets to build the emulated tls
routines as weak definitions, for example.
If there is no definition, fall back to the default. */
#ifndef EMUTLS_ATTR
# define EMUTLS_ATTR
#endif
/* __emutls_get_address and __emutls_register_common are registered as
builtins, but the compiler struct __emutls_object doesn't have
a union in there and is only created when actually needed for
the calls to the builtins, so the builtins are created with void *
arguments rather than struct __emutls_object *. Avoid
-Wbuiltin-declaration-mismatch warnings. */
#pragma GCC diagnostic ignored "-Wbuiltin-declaration-mismatch"
EMUTLS_ATTR
void *__emutls_get_address (struct __emutls_object *);
EMUTLS_ATTR
void __emutls_register_common (struct __emutls_object *, word, word, void *);
#ifdef __GTHREADS
#ifdef __GTHREAD_MUTEX_INIT
static __gthread_mutex_t emutls_mutex = __GTHREAD_MUTEX_INIT;
#else
static __gthread_mutex_t emutls_mutex;
#endif
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)
{
#ifndef __GTHREAD_MUTEX_INIT
__GTHREAD_MUTEX_INIT_FUNCTION (&emutls_mutex);
#endif
if (__gthread_key_create (&emutls_key, emutls_destroy) != 0)
abort ();
}
#endif
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;
}
/* Despite applying the attribute to the declaration, in this case the mis-
match between the builtin's declaration [void * (*)(void *)] and the
implementation here, causes the decl. attributes to be discarded. */
EMUTLS_ATTR void *
__emutls_get_address (struct __emutls_object *obj)
{
if (! __gthread_active_p ())
{
if (__builtin_expect (obj->loc.ptr == NULL, 0))
obj->loc.ptr = emutls_alloc (obj);
return obj->loc.ptr;
}
#ifndef __GTHREADS
abort ();
#else
pointer offset = __atomic_load_n (&obj->loc.offset, __ATOMIC_ACQUIRE);
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;
__atomic_store_n (&obj->loc.offset, offset, __ATOMIC_RELEASE);
}
__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;
#endif
}
EMUTLS_ATTR 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;
}