1 files changed, 79 insertions, 0 deletions
diff --git a/libgcc/enable-execute-stack-mprotect.c b/libgcc/enable-execute-stack-mprotect.c
new file mode 100644
index 0000000000..b038657907
--- /dev/null
+++ b/libgcc/enable-execute-stack-mprotect.c
@@ -0,0 +1,79 @@
+/* Implement __enable_execute_stack using mprotect(2).
+   Copyright (C) 2011-2017 Free Software Foundation, Inc.
+
+   This file is part of GCC.
+
+   GCC 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, or (at your option) any later
+   version.
+
+   GCC 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 <sys/mman.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+#define STACK_PROT_RWX (PROT_READ | PROT_WRITE | PROT_EXEC)
+
+static int need_enable_exec_stack;
+
+static void check_enabling (void) __attribute__ ((unused));
+extern void __enable_execute_stack (void *);
+
+#if defined __sun__ && defined __svr4__
+static void __attribute__ ((constructor))
+check_enabling (void)
+{
+  int prot = (int) sysconf (_SC_STACK_PROT);
+
+  if (prot != STACK_PROT_RWX)
+    need_enable_exec_stack = 1;
+}
+#else
+/* There is no way to query the execute permission of the stack, so
+   we always issue the mprotect() call.  */
+
+static int need_enable_exec_stack = 1;
+#endif
+
+/* Attempt to turn on access permissions for the stack.  Unfortunately it
+   is not possible to make this namespace-clean.*/
+
+void
+__enable_execute_stack (void *addr)
+{
+  if (!need_enable_exec_stack)
+    return;
+  else
+    {
+      static long size, mask;
+
+      if (size == 0) {
+	size = getpagesize ();
+	mask = ~(size - 1);
+      }
+
+      char *page = (char *) (((long) addr) & mask);
+      char *end  = (char *)
+	((((long) (addr + __LIBGCC_TRAMPOLINE_SIZE__)) & mask) + size);
+
+      if (mprotect (page, end - page, STACK_PROT_RWX) < 0)
+	/* Note that no errors should be emitted by this code; it is
+	   considered dangerous for library calls to send messages to
+	   stdout/stderr.  */
+	abort ();
+    }
+}