emutramp

Index: libffi/ChangeLog
===================================================================
--- libffi.orig/ChangeLog
+++ libffi/ChangeLog
@@ -1,3 +1,11 @@
+2012-10-30  Magnus Granberg  <zorry@gentoo.org>
+	    Pavel Labushev  <pavel.labushev@runbox.ru>
+
+	* configure.ac: New options pax_emutramp
+	* configure, fficonfig.h.in: Regenerated
+	* src/closures.c: New function emutramp_enabled_check() and
+	checks.
+
 2012-10-30  Frederick Cheung  <frederick.cheung@gmail.com>
 
 	* configure.ac: Enable FFI_MAP_EXEC_WRIT for Darwin 12 (mountain
Index: libffi/README
===================================================================
--- libffi.orig/README
+++ libffi/README
@@ -154,6 +154,7 @@ See the ChangeLog files for details.
 	Add Blackfin support.
 	Add TILE-Gx/TILEPro support.
 	Add AArch64 support.
+	Add support for PaX enabled kernels with MPROTECT.
 
 3.0.11 Apr-11-12
         Lots of build fixes.
Index: libffi/configure
===================================================================
--- libffi.orig/configure
+++ libffi/configure
@@ -826,6 +826,7 @@ enable_libtool_lock
 enable_portable_binary
 with_gcc_arch
 enable_maintainer_mode
+enable_pax_emutramp
 enable_debug
 enable_structs
 enable_raw_api
@@ -1473,6 +1474,7 @@ Optional Features:
                           unportable binaries
   --enable-maintainer-mode  enable make rules and dependencies not useful
 			  (and sometimes confusing) to the casual installer
+  --enable-pax_emutramp       enable pax emulated trampolines, for we can't use PROT_EXEC
   --enable-debug          debugging mode
   --disable-structs       omit code for struct support
   --disable-raw-api       make the raw api unavailable
@@ -14457,6 +14459,16 @@ $as_echo "#define SYMBOL_UNDERSCORE 1" >
     fi
 fi
 
+# On PaX enable kernels that have MPROTECT enable we can't use PROT_EXEC.
+# Check whether --enable-pax_emutramp was given.
+if test "${enable_pax_emutramp+set}" = set; then :
+  enableval=$enable_pax_emutramp; if test "$enable_pax_emutramp" = "yes"; then
+
+$as_echo "#define FFI_MMAP_EXEC_EMUTRAMP_PAX 1" >>confdefs.h
+
+  fi
+fi
+
 
 FFI_EXEC_TRAMPOLINE_TABLE=0
 case "$target" in
Index: libffi/configure.ac
===================================================================
--- libffi.orig/configure.ac
+++ libffi/configure.ac
@@ -352,6 +352,13 @@ if test x$TARGET = xX86_WIN64; then
     fi
 fi
 
+# On PaX enable kernels that have MPROTECT enable we can't use PROT_EXEC.
+AC_ARG_ENABLE(pax_emutramp,
+  [  --enable-pax_emutramp       enable pax emulated trampolines, for we can't use PROT_EXEC],
+  if test "$enable_pax_emutramp" = "yes"; then
+    AC_DEFINE(FFI_MMAP_EXEC_EMUTRAMP_PAX, 1,
+      [Define this if you want to enable pax emulated trampolines])
+  fi)
 
 FFI_EXEC_TRAMPOLINE_TABLE=0
 case "$target" in
Index: libffi/src/closures.c
===================================================================
--- libffi.orig/src/closures.c
+++ libffi/src/closures.c
@@ -172,6 +172,27 @@ selinux_enabled_check (void)
 
 #endif /* !FFI_MMAP_EXEC_SELINUX */
 
+/* On PaX enable kernels that have MPROTECT enable we can't use PROT_EXEC. */
+#ifdef FFI_MMAP_EXEC_EMUTRAMP_PAX
+#include <stdlib.h>
+
+static int emutramp_enabled = -1;
+
+static int
+emutramp_enabled_check (void)
+{
+  if (getenv ("FFI_DISABLE_EMUTRAMP") == NULL)
+    return 1;
+  else
+    return 0;
+}
+
+#define is_emutramp_enabled() (emutramp_enabled >= 0 ? emutramp_enabled \
+                               : (emutramp_enabled = emutramp_enabled_check ()))
+#else
+#define is_emutramp_enabled() 0
+#endif /* FFI_MMAP_EXEC_EMUTRAMP_PAX */
+
 #elif defined (__CYGWIN__) || defined(__INTERIX)
 
 #include <sys/mman.h>
@@ -458,6 +479,12 @@ dlmmap (void *start, size_t length, int
   printf ("mapping in %zi\n", length);
 #endif
 
+  if (execfd == -1 && is_emutramp_enabled ())
+    {
+      ptr = mmap (start, length, prot & ~PROT_EXEC, flags, fd, offset);
+      return ptr;
+    }
+
   if (execfd == -1 && !is_selinux_enabled ())
     {
       ptr = mmap (start, length, prot | PROT_EXEC, flags, fd, offset);