1 files changed, 90 insertions, 0 deletions
diff --git a/newlib/libc/sys/or1k/mlock.c b/newlib/libc/sys/or1k/mlock.c
new file mode 100644
index 000000000..660c3f087
--- /dev/null
+++ b/newlib/libc/sys/or1k/mlock.c
@@ -0,0 +1,90 @@
+/* malloc-lock.c. Lock malloc.
+ *
+ * Copyright (C) 2014, Authors
+ *
+ * Contributor Stefan Wallentowitz <stefan.wallentowitz@tum.de>
+ *
+ * The authors hereby grant permission to use, copy, modify, distribute,
+ * and license this software and its documentation for any purpose, provided
+ * that existing copyright notices are retained in all copies and that this
+ * notice is included verbatim in any distributions. No written agreement,
+ * license, or royalty fee is required for any of the authorized uses.
+ * Modifications to this software may be copyrighted by their authors
+ * and need not follow the licensing terms described here, provided that
+ * the new terms are clearly indicated on the first page of each file where
+ * they apply.
+ */
+
+#include <reent.h>
+#include <or1k-support.h>
+
+/* Lock calls from different cores, but allows recursive calls from the same
+ * core. The lock is not only atomic to other cores calling malloc, but also
+ * disables all external interrupts. This is necessary as it could otherwise
+ * lead to a deadlock to interrupt while in malloc and then call it from an
+ * exception. But as we want the exceptions to be flexible to use all library
+ * calls and especially memory management this is necessary.
+ */
+
+// The lock. It is zero when unlocked and contains a unique value for each core.
+// This value is not the core id (to avoid id zero), but the pointer value of
+// the core specific struct _reent.
+volatile uint32_t _or1k_malloc_lock;
+
+// Count how often the current holder has entered the lock
+volatile uint32_t _or1k_malloc_lock_cnt;
+// The exception enable restore of the current mutex holder
+volatile uint32_t _or1k_malloc_lock_restore;
+
+/**
+ * Recursive lock of the malloc
+ */
+void __malloc_lock(struct _reent *ptr) {
+	uint32_t restore;
+	uint32_t id;
+
+	// Each core is identified by its struct _reent pointer
+	id = (uint32_t) ptr;
+
+	// Disable timer and interrupt exception, save TEE and IEE flag
+	// temporarily to restore them later on unlock
+	restore = or1k_critical_begin();
+
+	// We cannot be disturbed by an interrupt or timer exception from here
+
+	// Check if we currently don't hold the lock
+	if (_or1k_malloc_lock != id) {
+		do {
+			// Repeatedly check the lock until it is set to zero
+			while (_or1k_malloc_lock != 0) {}
+			// .. and then try to set it atomically. As this may
+			// fail, we need to repeat this
+		} while (or1k_sync_cas(&_or1k_malloc_lock, 0, id) != 0);
+	}
+
+	// Store the TEE and IEE flags for later restore
+	_or1k_malloc_lock_restore = restore;
+
+	// Increment counter. The lock may be accessed recursively
+	_or1k_malloc_lock_cnt++;
+
+	return;
+}
+
+void __malloc_unlock(struct _reent *ptr) {
+	// Decrement counter. The lock may be unlocked recursively
+	_or1k_malloc_lock_cnt--;
+
+	// If this was the last recursive unlock call
+	if(_or1k_malloc_lock_cnt == 0){
+		// We need to temporarily store the value to avoid a race
+		// condition between unlocking and reading restore
+		uint32_t restore = _or1k_malloc_lock_restore;
+		// unset lock
+		_or1k_malloc_lock = 0;
+		// Restore flags
+		or1k_critical_end(_or1k_malloc_lock_restore);
+	}
+
+	return;
+}