1 files changed, 116 insertions, 0 deletions
diff --git a/libatomic/config/posix/lock.c b/libatomic/config/posix/lock.c
new file mode 100644
index 00000000000..e57d3330faa
--- /dev/null
+++ b/libatomic/config/posix/lock.c
@@ -0,0 +1,116 @@
+/* Copyright (C) 2012 Free Software Foundation, Inc.
+   Contributed by Richard Henderson <rth@redhat.com>.
+
+   This file is part of the GNU Atomic Library (libatomic).
+
+   Libatomic 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 of the License, or
+   (at your option) any later version.
+
+   Libatomic 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 "libatomic_i.h"
+#include <pthread.h>
+
+
+/* The target page size.  Must be no larger than the runtime page size,
+   lest locking fail with virtual address aliasing (i.e. a page mmaped
+   at two locations).  */
+#ifndef PAGE_SIZE
+#define PAGE_SIZE	4096
+#endif
+
+/* The target cacheline size.  This is an optimization; the padding that
+   should be applied to the locks to keep them from interfering.  */
+#ifndef CACHLINE_SIZE
+#define CACHLINE_SIZE	64
+#endif
+
+/* The granularity at which locks are applied.  Almost certainly the
+   cachline size is the right thing to use here.  */
+#ifndef WATCH_SIZE
+#define WATCH_SIZE	CACHLINE_SIZE
+#endif
+
+struct lock
+{
+  pthread_mutex_t mutex;
+  char pad[sizeof(pthread_mutex_t) < CACHLINE_SIZE
+	   ? CACHLINE_SIZE - sizeof(pthread_mutex_t)
+	   : 0];
+};
+
+#define NLOCKS		(PAGE_SIZE / WATCH_SIZE)
+static struct lock locks[NLOCKS] = {
+  [0 ... NLOCKS-1].mutex = PTHREAD_MUTEX_INITIALIZER
+};
+
+static inline uintptr_t 
+addr_hash (void *ptr)
+{
+  return ((uintptr_t)ptr / WATCH_SIZE) % NLOCKS;
+}
+
+void
+libat_lock_1 (void *ptr)
+{
+  pthread_mutex_lock (&locks[addr_hash (ptr)].mutex);
+}
+
+void
+libat_unlock_1 (void *ptr)
+{
+  pthread_mutex_unlock (&locks[addr_hash (ptr)].mutex);
+}
+
+void
+libat_lock_n (void *ptr, size_t n)
+{
+  uintptr_t h = addr_hash (ptr);
+  size_t i = 0;
+
+  /* Don't lock more than all the locks we have.  */
+  if (n > PAGE_SIZE)
+    n = PAGE_SIZE;
+
+  do
+    {
+      pthread_mutex_lock (&locks[h].mutex);
+      if (++h == NLOCKS)
+	h = 0;
+      i += WATCH_SIZE;
+    }
+  while (i < n);
+}
+
+void
+libat_unlock_n (void *ptr, size_t n)
+{
+  uintptr_t h = addr_hash (ptr);
+  size_t i = 0;
+
+  if (n > PAGE_SIZE)
+    n = PAGE_SIZE;
+
+  do
+    {
+      pthread_mutex_unlock (&locks[h].mutex);
+      if (++h == NLOCKS)
+	h = 0;
+      i += WATCH_SIZE;
+    }
+  while (i < n);
+}