x86: add testcases for RODATA and NX protections/attributes

Latest update; I now have 4 NX tests, but 2 fail so they're #if 0'd.
I also cleaned up the NX test code quite a bit, and got rid of the ugly
exception table sorting stuff.

From: Arjan van de Ven <arjan@linux.intel.com>

This patch adds testcases for the CONFIG_DEBUG_RODATA configuration option
as well as the NX CPU feature/mappings. Both testcases can move to tests/
once that patch gets merged into mainline.
(I'm half considering moving the rodata test into mm/init.c but I'll
wait with that until init.c is unified)

As part of this I had to fix a not-quite-right alignment in the vmlinux.lds.h
for the RODATA sections, which lead to 1 page less being marked read only.

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

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 4d1156545194..a72737c05747 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -736,6 +736,8 @@ static int noinline do_test_wp_bit(void)
 }
 
 #ifdef CONFIG_DEBUG_RODATA
+const int rodata_test_data = 0xC3;
+EXPORT_SYMBOL_GPL(rodata_test_data);
 
 void mark_rodata_ro(void)
 {
@@ -765,6 +767,7 @@ void mark_rodata_ro(void)
         set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
         printk("Write protecting the kernel read-only data: %luk\n",
                size >> 10);
+        rodata_test();
 
 #ifdef CONFIG_CPA_DEBUG
         printk("Testing CPA: undo %lx-%lx\n", start, start + size);