[PATCH] Fix pte_exec/mkexec and use it in change_page_attr()

Fix the pte_exec/mkexec page table accessor functions to really
use the NX bit. Previously they only checked the USER bit, but
weren't actually used for anything.

Then use them in change_page_attr() to manipulate the NX bit
properly.

Signed-off-by: Andi Kleen <ak@suse.de>

1 files changed, 5 insertions, 3 deletions

diff --git a/arch/x86_64/mm/pageattr.c b/arch/x86_64/mm/pageattr.c
index 2685b1f3671c..01591b649f4e 100644
--- a/arch/x86_64/mm/pageattr.c
+++ b/arch/x86_64/mm/pageattr.c
@@ -190,10 +190,12 @@ int change_page_attr_addr(unsigned long address, int numpages, pgprot_t prot)
                  * lowmem */
                 if (__pa(address) < KERNEL_TEXT_SIZE) {
                         unsigned long addr2;
-                        pgprot_t prot2 = prot;
+                        pgprot_t prot2;
                         addr2 = __START_KERNEL_map + __pa(address);
-                        pgprot_val(prot2) &= ~_PAGE_NX;
-                        err = __change_page_attr(addr2, pfn, prot2, PAGE_KERNEL_EXEC);
+                        /* Make sure the kernel mappings stay executable */
+                        prot2 = pte_pgprot(pte_mkexec(pfn_pte(0, prot)));
+                        err = __change_page_attr(addr2, pfn, prot2,
+                                                 PAGE_KERNEL_EXEC);
                 } 
         }       
         up_write(&init_mm.mmap_sem);