x86-64: align RODATA kernel section to 2MB with CONFIG_DEBUG_RODATA

[pandora-kernel.git] / arch / x86 / mm / pageattr.c

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index dd38bfb..b494fc4 100644 (file)
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -279,6 +279,20 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
                   __pa((unsigned long)__end_rodata) >> PAGE_SHIFT))
                pgprot_val(forbidden) |= _PAGE_RW;
 
+#if defined(CONFIG_X86_64) && defined(CONFIG_DEBUG_RODATA)
+       /*
+        * Kernel text mappings for the large page aligned .rodata section
+        * will be read-only. For the kernel identity mappings covering
+        * the holes caused by this alignment can be anything.
+        *
+        * This will preserve the large page mappings for kernel text/data
+        * at no extra cost.
+        */
+       if (within(address, (unsigned long)_text,
+                  (unsigned long)__end_rodata_hpage_align))
+               pgprot_val(forbidden) |= _PAGE_RW;
+#endif
+
        prot = __pgprot(pgprot_val(prot) & ~pgprot_val(forbidden));
 
        return prot;