2008-09-19 Christian Franke <franke@computer.org>

* aclocal.m4 (grub_CHECK_ENABLE_EXECUTE_STACK): New function.
	* configure.ac: Call grub_CHECK_ENABLE_EXECUTE_STACK.
	* include/grub/misc.h [NEED_ENABLE_EXECUTE_STACK]:
	Export __enable_execute_stack() to modules.
	* kern/misc.c [NEED_ENABLE_EXECUTE_STACK] (__enable_execute_stack):
	New function.

ChangeLog

@@ -1,3 +1,12 @@
+2008-09-19  Christian Franke  <franke@computer.org>
+
+	* aclocal.m4 (grub_CHECK_ENABLE_EXECUTE_STACK): New function.
+	* configure.ac: Call grub_CHECK_ENABLE_EXECUTE_STACK.
+	* include/grub/misc.h [NEED_ENABLE_EXECUTE_STACK]:
+	Export __enable_execute_stack() to modules.
+	* kern/misc.c [NEED_ENABLE_EXECUTE_STACK] (__enable_execute_stack):
+	New function.
+
 2008-09-09  Felix Zielcke  <fzielcke@z-51.de>
 
 	* Makefile.in (RMKFILES): Add `i386.rmk' and `x86_64-efi.rmk'.

aclocal.m4

@@ -379,6 +379,33 @@ dnl So use regparm 2 until a better test is found.
 	[Catch gcc bug])
 fi
 ])
+
+dnl Check if the C compiler generates calls to `__enable_execute_stack()'.
+AC_DEFUN(grub_CHECK_ENABLE_EXECUTE_STACK,[
+AC_MSG_CHECKING([whether `$CC' generates calls to `__enable_execute_stack()'])
+AC_LANG_CONFTEST([[
+void f (int (*p) (void));
+void g (int i)
+{
+  int nestedfunc (void) { return i; }
+  f (nestedfunc);
+}
+]])
+if AC_TRY_COMMAND([${CC-cc} ${CFLAGS} -S conftest.c]) && test -s conftest.s; then
+  true
+else
+  AC_MSG_ERROR([${CC-cc} failed to produce assembly code])
+fi
+if grep __enable_execute_stack conftest.s >/dev/null 2>&1; then
+  AC_DEFINE([NEED_ENABLE_EXECUTE_STACK], 1,
+	    [Define to 1 if GCC generates calls to __enable_execute_stack()])
+  AC_MSG_RESULT([yes])
+else
+  AC_MSG_RESULT([no])
+fi
+rm -f conftest*
+])
+
 
 dnl Check if the C compiler supports `-fstack-protector'.
 AC_DEFUN(grub_CHECK_STACK_PROTECTOR,[

config.h.in

@@ -79,6 +79,9 @@
 /* Define to 1 if you enable memory manager debugging. */
 #undef MM_DEBUG
 
+/* Define to 1 if GCC generates calls to __enable_execute_stack() */
+#undef NEED_ENABLE_EXECUTE_STACK
+
 /* Catch gcc bug */
 #undef NESTED_FUNC_ATTR
 

configure

@@ -6775,6 +6775,47 @@ fi
 # Compiler features.
 #
 
+# Need __enable_execute_stack() for nested function trampolines?
+
+{ echo "$as_me:$LINENO: checking whether \`$CC' generates calls to \`__enable_execute_stack()'" >&5
+echo $ECHO_N "checking whether \`$CC' generates calls to \`__enable_execute_stack()'... $ECHO_C" >&6; }
+cat >conftest.$ac_ext <<_ACEOF
+
+void f (int (*p) (void));
+void g (int i)
+{
+  int nestedfunc (void) { return i; }
+  f (nestedfunc);
+}
+
+_ACEOF
+if { ac_try='${CC-cc} ${CFLAGS} -S conftest.c'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } && test -s conftest.s; then
+  true
+else
+  { { echo "$as_me:$LINENO: error: ${CC-cc} failed to produce assembly code" >&5
+echo "$as_me: error: ${CC-cc} failed to produce assembly code" >&2;}
+   { (exit 1); exit 1; }; }
+fi
+if grep __enable_execute_stack conftest.s >/dev/null 2>&1; then
+
+cat >>confdefs.h <<\_ACEOF
+#define NEED_ENABLE_EXECUTE_STACK 1
+_ACEOF
+
+  { echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6; }
+else
+  { echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6; }
+fi
+rm -f conftest*
+
+
 # Smashing stack protector.
 
 # Smashing stack protector.

configure.ac

@@ -305,6 +305,9 @@ fi
 # Compiler features.
 #
 
+# Need __enable_execute_stack() for nested function trampolines?
+grub_CHECK_ENABLE_EXECUTE_STACK
+
 # Smashing stack protector.
 grub_CHECK_STACK_PROTECTOR
 # Need that, because some distributions ship compilers that include

include/grub/misc.h

@@ -82,6 +82,10 @@ grub_ssize_t EXPORT_FUNC(grub_utf8_to_ucs4) (grub_uint32_t *dest,
 grub_uint64_t EXPORT_FUNC(grub_divmod64) (grub_uint64_t n,
 					  grub_uint32_t d, grub_uint32_t *r);
 
+#ifdef NEED_ENABLE_EXECUTE_STACK
+void EXPORT_FUNC(__enable_execute_stack) (void *addr);
+#endif
+
 /* Inline functions.  */
 
 static inline unsigned int

kern/misc.c

@@ -1036,3 +1036,12 @@ grub_abort (void)
 }
 /* GCC emits references to abort().  */
 void abort (void) __attribute__ ((alias ("grub_abort")));
+
+#ifdef NEED_ENABLE_EXECUTE_STACK
+/* Some gcc versions generate a call to this function
+   in trampolines for nested functions.  */
+__enable_execute_stack (void *addr __attribute__ ((unused)))
+{
+}
+#endif
+