c_p_a(): do a simple self test at boot

When CONFIG_DEBUG_RODATA is enabled undo the ro mapping and redo it again.
This gives some simple testing for change_page_attr().

Signed-off-by: Andi Kleen <ak@suse.de>
Acked-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 10 insertions, 0 deletions

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 8198840c3dcb..0fd9d7f77786 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -606,6 +606,16 @@ void mark_rodata_ro(void)
          * of who is the culprit.
          */
         global_flush_tlb();
+
+#ifdef CONFIG_CPA_DEBUG
+        printk("Testing CPA: undo %lx-%lx\n", start, end);
+        change_page_attr_addr(start, (end - start) >> PAGE_SHIFT, PAGE_KERNEL);
+        global_flush_tlb();
+
+        printk("Testing CPA: again\n");
+        change_page_attr_addr(start, (end - start) >> PAGE_SHIFT, PAGE_KERNEL_RO);
+        global_flush_tlb();
+#endif
 }
 #endif