Remove 80386 support from the ELF run time linker.
This commit is contained in:
John Baldwin
parent
2d68e3fb92
commit
165204a75f
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=137785
@ -1,144 +0,0 @@
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/*-
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* Copyright 1999, 2000 John D. Polstra.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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/*
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* Thread locking implementation for the dynamic linker.
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*
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* On 80486 and later CPUs we use the "simple, non-scalable
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* reader-preference lock" from:
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*
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* J. M. Mellor-Crummey and M. L. Scott. "Scalable Reader-Writer
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* Synchronization for Shared-Memory Multiprocessors." 3rd ACM Symp. on
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* Principles and Practice of Parallel Programming, April 1991.
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*
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* In this algorithm the lock is a single word. Its low-order bit is
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* set when a writer holds the lock. The remaining high-order bits
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* contain a count of readers desiring the lock. The algorithm requires
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* atomic "compare_and_store" and "add" operations.
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*
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* The "compare_and_store" operation requires the "cmpxchg" instruction
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* on the x86. Unfortunately, the 80386 CPU does not support that
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* instruction -- only the 80486 and later models support it. So on the
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* 80386 we must use simple test-and-set exclusive locks instead. We
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* determine which kind of lock to use by trying to execute a "cmpxchg"
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* instruction and catching the SIGILL which results on the 80386.
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*/
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#include <setjmp.h>
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#include <signal.h>
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static inline int
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cmpxchgl(int old, int new, volatile int *m)
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{
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int result;
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__asm __volatile ("lock; cmpxchgl %2, %0"
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: "+m"(*m), "=a"(result)
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: "r"(new), "1"(old)
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: "cc");
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return result;
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}
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static inline int
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xchgl(int v, volatile int *m)
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{
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int result;
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__asm __volatile ("xchgl %0, %1"
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: "=r"(result), "+m"(*m)
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: "0"(v));
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return result;
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}
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/*
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* Crude exclusive locks for the 80386, which does not support the
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* cmpxchg instruction.
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*/
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static void
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lock80386_acquire(void *lock)
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{
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Lock *l = (Lock *)lock;
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sigset_t tmp_oldsigmask;
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for ( ; ; ) {
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sigprocmask(SIG_BLOCK, &fullsigmask, &tmp_oldsigmask);
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if (xchgl(1, &l->lock) == 0)
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break;
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sigprocmask(SIG_SETMASK, &tmp_oldsigmask, NULL);
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while (l->lock != 0)
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; /* Spin */
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}
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oldsigmask = tmp_oldsigmask;
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}
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static void
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lock80386_release(void *lock)
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{
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Lock *l = (Lock *)lock;
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l->lock = 0;
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sigprocmask(SIG_SETMASK, &oldsigmask, NULL);
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}
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/*
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* Code to determine at runtime whether the CPU supports the cmpxchg
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* instruction. This instruction allows us to use locks that are more
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* efficient, but it didn't exist on the 80386.
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*/
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static jmp_buf sigill_env;
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static void
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sigill(int sig)
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{
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longjmp(sigill_env, 1);
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}
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static int
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cpu_supports_cmpxchg(void)
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{
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struct sigaction act, oact;
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int result;
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volatile int lock;
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memset(&act, 0, sizeof act);
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act.sa_handler = sigill;
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sigemptyset(&act.sa_mask);
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act.sa_flags = 0;
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sigaction(SIGILL, &act, &oact);
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if (setjmp(sigill_env) == 0) {
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lock = 0;
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cmpxchgl(0, 1, &lock);
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result = 1;
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} else
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result = 0;
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sigaction(SIGILL, &oact, NULL);
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return result;
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}
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@ -137,16 +137,6 @@ def_lock_release(void *lock)
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}
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}
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#if __i386__
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/*
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* Import a crude exclusive lock implementation for i386 processors.
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* This file will be removed once i386 support is deprecated in favor
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* of i486+.
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*/
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#include "i386/lockdflt.c"
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#endif
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static int
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def_thread_set_flag(int mask)
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{
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@ -250,15 +240,6 @@ lockdflt_init()
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rtld_locks[i].handle = NULL;
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}
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#if __i386__
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if (!cpu_supports_cmpxchg()) {
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/* It's a cruddy old 80386. */
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deflockinfo.rlock_acquire = lock80386_acquire;
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deflockinfo.wlock_acquire = lock80386_acquire;
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deflockinfo.lock_release = lock80386_release;
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}
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#endif
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memcpy(&lockinfo, &deflockinfo, sizeof(lockinfo));
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_rtld_thread_init(NULL);
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/*
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