[PATCH 2/2] arm: apply more __ro_after_init

On Wednesday, August 10, 2016 10:43:39 AM CEST Russell King - ARM Linux wrote:

On Fri, Jun 03, 2016 at 11:40:24AM -0700, Kees Cook wrote:

quoted

@@ -1309,16 +1309,11 @@ void __init arm_mm_memblock_reserve(void)
  * Any other function or debugging method which may touch any device _will_
  * crash the kernel.
  */
+static char vectors[PAGE_SIZE * 2] __ro_after_init __aligned(PAGE_SIZE);
 static void __init devicemaps_init(const struct machine_desc *mdesc)
 {
      struct map_desc map;
      unsigned long addr;
-     void *vectors;
-
-     /*
-      * Allocate the vector page early.
-      */
-     vectors = early_alloc(PAGE_SIZE * 2);

This one is not appropriate.  We _do_ write to these pages after init
for FIQ handler updates.  See set_fiq_handler().

Is that the only thing that modifies the page? If we think this is a
valuable change, we could make it depend on the absence of FIQ
support, as very few platforms (rpc, omap1, s3c24xx and possibly
imx) seem to even use it.

	Arnd