x86: mark the .rodata section also NX

The .rodata section shouldn't just be read-only,
but also non-executable. This is free since we've broken
up the 2MB page already anyway.

also update test_nx to check for this.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 8 insertions, 1 deletions

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 3a98d6f724ab..9b61c75a2355 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -591,10 +591,17 @@ void mark_rodata_ro(void)
         if (end <= start)
                 return;
 
-        set_memory_ro(start, (end - start) >> PAGE_SHIFT);
 
         printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n",
                (end - start) >> 10);
+        set_memory_ro(start, (end - start) >> PAGE_SHIFT);
+
+        /*
+         * The rodata section (but not the kernel text!) should also be
+         * not-executable.
+         */
+        start = ((unsigned long)__start_rodata + PAGE_SIZE - 1) & PAGE_MASK;
+        set_memory_nx(start, (end - start) >> PAGE_SHIFT);
 
         rodata_test();