From 0ecb606cb6cf65de1d9fc8a919bceb4be476c602 Mon Sep 17 00:00:00 2001
From: Jakub Jelinek <jakub@redhat.com>
Date: Thu, 12 Jul 2007 18:26:36 +0000
Subject: 2.5-18.1

---
 nptl/sysdeps/unix/sysv/linux/rtld-lowlevel.h | 153 +++++++++++++++++++++++++++
 1 file changed, 153 insertions(+)
 create mode 100644 nptl/sysdeps/unix/sysv/linux/rtld-lowlevel.h

(limited to 'nptl/sysdeps/unix/sysv/linux/rtld-lowlevel.h')

diff --git a/nptl/sysdeps/unix/sysv/linux/rtld-lowlevel.h b/nptl/sysdeps/unix/sysv/linux/rtld-lowlevel.h
new file mode 100644
index 0000000000..39db5a3bd4
--- /dev/null
+++ b/nptl/sysdeps/unix/sysv/linux/rtld-lowlevel.h
@@ -0,0 +1,153 @@
+/* Defintions for lowlevel handling in ld.so.
+   Copyright (C) 2006, 2007 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#ifndef _RTLD_LOWLEVEL_H
+#define  _RTLD_LOWLEVEL_H 1
+
+#include <atomic.h>
+#include <lowlevellock.h>
+
+
+/* Special multi-reader lock used in ld.so.  */
+#define __RTLD_MRLOCK_WRITER 1
+#define __RTLD_MRLOCK_RWAIT 2
+#define __RTLD_MRLOCK_WWAIT 4
+#define __RTLD_MRLOCK_RBITS \
+  ~(__RTLD_MRLOCK_WRITER | __RTLD_MRLOCK_RWAIT | __RTLD_MRLOCK_WWAIT)
+#define __RTLD_MRLOCK_INC 8
+#define __RTLD_MRLOCK_TRIES 5
+
+
+typedef int __rtld_mrlock_t;
+
+
+#define __rtld_mrlock_define(CLASS,NAME) \
+  CLASS __rtld_mrlock_t NAME;
+
+
+#define _RTLD_MRLOCK_INITIALIZER 0
+#define __rtld_mrlock_initialize(NAME) \
+  (void) ((NAME) = 0)
+
+
+#define __rtld_mrlock_lock(lock) \
+  do {									      \
+    __label__ out;							      \
+    while (1)								      \
+      {									      \
+	int oldval;							      \
+	for (int tries = 0; tries < __RTLD_MRLOCK_TRIES; ++tries)	      \
+	  {								      \
+	    oldval = lock;						      \
+	    while (__builtin_expect ((oldval				      \
+				      & (__RTLD_MRLOCK_WRITER		      \
+					 | __RTLD_MRLOCK_WWAIT))	      \
+				     == 0, 1))				      \
+	      {								      \
+		int newval = ((oldval & __RTLD_MRLOCK_RBITS)		      \
+			      + __RTLD_MRLOCK_INC);			      \
+		int ret = atomic_compare_and_exchange_val_acq (&(lock),	      \
+							       newval,	      \
+							       oldval);	      \
+		if (__builtin_expect (ret == oldval, 1))		      \
+		  goto out;						      \
+		oldval = ret;						      \
+	      }								      \
+	    atomic_delay ();						      \
+	  }								      \
+	if ((oldval & __RTLD_MRLOCK_RWAIT) == 0)			      \
+	  {								      \
+	    atomic_or (&(lock), __RTLD_MRLOCK_RWAIT);			      \
+	    oldval |= __RTLD_MRLOCK_RWAIT;				      \
+	  }								      \
+	lll_futex_wait (lock, oldval);					      \
+      }									      \
+  out:;									      \
+  } while (0)
+
+
+#define __rtld_mrlock_unlock(lock) \
+  do {									      \
+    int oldval = atomic_exchange_and_add (&(lock), -__RTLD_MRLOCK_INC);	      \
+    if (__builtin_expect ((oldval					      \
+			   & (__RTLD_MRLOCK_RBITS | __RTLD_MRLOCK_WWAIT))     \
+			  == (__RTLD_MRLOCK_INC | __RTLD_MRLOCK_WWAIT), 0))   \
+      /* We have to wake all threads since there might be some queued	      \
+	 readers already.  */						      \
+      lll_futex_wake (&(lock), 0x7fffffff);				      \
+  } while (0)
+
+
+/* There can only ever be one thread trying to get the exclusive lock.  */
+#define __rtld_mrlock_change(lock) \
+  do {									      \
+    __label__ out;							      \
+    while (1)								      \
+      {									      \
+	int oldval;							      \
+	for (int tries = 0; tries < __RTLD_MRLOCK_TRIES; ++tries)	      \
+	  {								      \
+	    oldval = lock;						      \
+	    while (__builtin_expect ((oldval & __RTLD_MRLOCK_RBITS) == 0, 1)) \
+	      {								      \
+		int newval = ((oldval & __RTLD_MRLOCK_RWAIT)		      \
+			      + __RTLD_MRLOCK_WRITER);			      \
+		int ret = atomic_compare_and_exchange_val_acq (&(lock),	      \
+							       newval,	      \
+							       oldval);	      \
+		if (__builtin_expect (ret == oldval, 1))		      \
+		  goto out;						      \
+		oldval = ret;						      \
+	      }								      \
+	    atomic_delay ();						      \
+	  }								      \
+	atomic_or (&(lock), __RTLD_MRLOCK_WWAIT);			      \
+	oldval |= __RTLD_MRLOCK_WWAIT;					      \
+	lll_futex_wait (lock, oldval);					      \
+      }									      \
+  out:;									      \
+  } while (0)
+
+
+#define __rtld_mrlock_done(lock) \
+  do {				 \
+    int oldval = atomic_exchange_and_add (&(lock), -__RTLD_MRLOCK_WRITER);    \
+    if (__builtin_expect ((oldval & __RTLD_MRLOCK_RWAIT) != 0, 0))	      \
+      lll_futex_wake (&(lock), 0x7fffffff);				      \
+  } while (0)
+
+
+/* Function to wait for variable become zero.  Used in ld.so for
+   reference counters.  */
+#define __rtld_waitzero(word) \
+  do {									      \
+    while (1)								      \
+      {									      \
+	int val = word;							      \
+	if (val == 0)							      \
+	  break;							      \
+	lll_futex_wait (&(word), val);					      \
+      }									      \
+  } while (0)
+
+
+#define __rtld_notify(word) \
+  lll_futex_wake (&(word), 1)
+
+#endif
-- 
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