1 files changed, 53 insertions, 0 deletions
diff --git a/libgo/runtime/go-trampoline.c b/libgo/runtime/go-trampoline.c
new file mode 100644
index 000000000..43003e81c
--- /dev/null
+++ b/libgo/runtime/go-trampoline.c
@@ -0,0 +1,53 @@
+/* go-trampoline.c -- allocate a trampoline for a nested function.
+
+   Copyright 2009 The Go Authors. All rights reserved.
+   Use of this source code is governed by a BSD-style
+   license that can be found in the LICENSE file.  */
+
+#include "config.h"
+
+#include <stddef.h>
+#include <stdint.h>
+#include <unistd.h>
+
+#ifdef HAVE_SYS_MMAN_H
+#include <sys/mman.h>
+#endif
+
+#include "go-alloc.h"
+#include "go-assert.h"
+
+/* In order to build a trampoline we need space which is both writable
+   and executable.  We currently just allocate a whole page.  This
+   needs to be more system dependent.  */
+
+void *
+__go_allocate_trampoline (size_t size, void *closure)
+{
+  unsigned int page_size;
+  void *ret;
+  size_t off;
+
+  page_size = getpagesize ();
+  __go_assert (page_size >= size);
+  ret = __go_alloc (2 * page_size - 1);
+  ret = (void *) (((uintptr_t) ret + page_size - 1)
+		  & ~ ((uintptr_t) page_size - 1));
+
+  /* Because the garbage collector only looks at correct address
+     offsets, we need to ensure that it will see the closure
+     address.  */
+  off = ((size + sizeof (void *) - 1) / sizeof (void *)) * sizeof (void *);
+  __go_assert (size + off + sizeof (void *) <= page_size);
+  __builtin_memcpy (ret + off, &closure, sizeof (void *));
+
+#ifdef HAVE_SYS_MMAN_H
+  {
+    int i;
+    i = mprotect (ret, size, PROT_READ | PROT_WRITE | PROT_EXEC);
+    __go_assert (i == 0);
+  }
+#endif
+
+  return ret;
+}