1100f84983
Implement reference counting of scope records. * elf/dl-close.c (_dl_close): Remove all scopes from removed objects from the list in objects which remain. Always allocate new scope record. * elf/dl-open.c (dl_open_worker): When growing array for scopes, don't resize, allocate a new one. * elf/dl-runtime.c: Update reference counters before using a scope array. * elf/dl-sym.c: Likewise. * elf/dl-libc.c: Adjust for l_scope name change. * elf/dl-load.c: Likewise. * elf/dl-object.c: Likewise. * elf/rtld.c: Likewise. * include/link.h: Inlcude <rtld-lowlevel.h>. Define struct r_scoperec. Replace r_scope with pointer to r_scoperec structure. Add l_scoperec_lock. * sysdeps/generic/ldsodefs.h: Include <rtld-lowlevel.h>. * sysdeps/generic/rtld-lowlevel.h: New file. * include/atomic.h: Rename atomic_and to atomic_and_val and atomic_or to atomic_or_val. Define new macros atomic_and and atomic_or which do not return values. * sysdeps/x86_64/bits/atomic.h: Define atomic_and and atomic_or. Various cleanups. * sysdeps/i386/i486/bits/atomic.h: Likewise.
152 lines
4.8 KiB
C
152 lines
4.8 KiB
C
/* Defintions for lowlevel handling in ld.so.
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Copyright (C) 2006 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#ifndef _RTLD_LOWLEVEL_H
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#define _RTLD_LOWLEVEL_H 1
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#include <atomic.h>
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#include <lowlevellock.h>
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/* Special multi-reader lock used in ld.so. */
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#define __RTLD_MRLOCK_WRITER 1
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#define __RTLD_MRLOCK_RWAIT 2
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#define __RTLD_MRLOCK_WWAIT 4
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#define __RTLD_MRLOCK_RBITS \
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~(__RTLD_MRLOCK_WRITER | __RTLD_MRLOCK_RWAIT | __RTLD_MRLOCK_WWAIT)
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#define __RTLD_MRLOCK_INC 8
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#define __RTLD_MRLOCK_TRIES 5
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typedef int __rtld_mrlock_t;
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#define __rtld_mrlock_define(CLASS,NAME) \
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CLASS __rtld_mrlock_t NAME;
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#define _RTLD_MRLOCK_INITIALIZER 0
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#define __rtld_mrlock_initialize(NAME) \
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(void) ((NAME) = 0
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#define __rtld_mrlock_lock(lock) \
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do { \
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__label__ out; \
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while (1) \
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{ \
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int oldval; \
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for (int tries = 0; tries < __RTLD_MRLOCK_TRIES; ++tries) \
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{ \
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oldval = lock; \
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while (__builtin_expect ((oldval \
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& (__RTLD_MRLOCK_WRITER \
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| __RTLD_MRLOCK_WWAIT)) \
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== 0, 1)) \
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{ \
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int newval = ((oldval & __RTLD_MRLOCK_RBITS) \
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+ __RTLD_MRLOCK_INC); \
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int ret = atomic_compare_and_exchange_val_acq (&(lock), \
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newval, \
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oldval); \
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if (__builtin_expect (ret == oldval, 1)) \
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goto out; \
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} \
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atomic_delay (); \
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} \
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if ((oldval & __RTLD_MRLOCK_RWAIT) == 0) \
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{ \
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atomic_or (&(lock), __RTLD_MRLOCK_RWAIT); \
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oldval |= __RTLD_MRLOCK_RWAIT; \
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} \
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lll_futex_wait (lock, oldval); \
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} \
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out:; \
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} while (0)
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#define __rtld_mrlock_unlock(lock) \
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do { \
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int oldval = atomic_exchange_and_add (&(lock), -__RTLD_MRLOCK_INC); \
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if (__builtin_expect ((oldval \
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& (__RTLD_MRLOCK_RBITS | __RTLD_MRLOCK_WWAIT)) \
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== __RTLD_MRLOCK_INC | __RTLD_MRLOCK_WWAIT, 0)) \
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/* We have to wake all threads since there might be some queued \
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readers already. */ \
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lll_futex_wake (&(lock), 0x7fffffff); \
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} while (0)
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/* There can only ever be one thread trying to get the exclusive lock. */
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#define __rtld_mrlock_change(lock) \
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do { \
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__label__ out; \
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while (1) \
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{ \
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int oldval; \
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for (int tries = 0; tries < __RTLD_MRLOCK_TRIES; ++tries) \
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{ \
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oldval = lock; \
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while (__builtin_expect ((oldval & __RTLD_MRLOCK_RBITS) == 0, 1))\
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{ \
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int newval = ((oldval & __RTLD_MRLOCK_RWAIT) \
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+ __RTLD_MRLOCK_WRITER); \
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int ret = atomic_compare_and_exchange_val_acq (&(lock), \
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newval, \
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oldval); \
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if (__builtin_expect (ret == oldval, 1)) \
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goto out; \
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} \
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atomic_delay (); \
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} \
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atomic_or (&(lock), __RTLD_MRLOCK_WWAIT); \
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oldval |= __RTLD_MRLOCK_WWAIT; \
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lll_futex_wait (lock, oldval); \
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} \
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out:; \
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} while (0)
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#define __rtld_mrlock_done(lock) \
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do { \
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int oldval = atomic_exchange_and_add (&(lock), -__RTLD_MRLOCK_WRITER); \
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if (__builtin_expect ((oldval & __RTLD_MRLOCK_RWAIT) != 0, 0)) \
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lll_futex_wake (&(lock), 0x7fffffff); \
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} while (0)
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/* Function to wait for variable become zero. Used in ld.so for
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reference counters. */
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#define __rtld_waitzero(word) \
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do { \
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while (1) \
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{ \
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int val = word; \
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if (val == 0) \
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break; \
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lll_futex_wait (&(word), val); \
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} \
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} while (0)
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#define __rtld_notify(word) \
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lll_futex_wake (&(word), 1)
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#endif
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