arm: Set TTB XN bit in case DCACHE_OFF for LPAE mode

While we setup the mmu initially we mark set_section_dcache with
DCACHE_OFF flag. In case of non-LPAE mode the DCACHE_OFF macro
is rightly defined with TTB_SECT_XN_MASK set so as to mark all the
4GB XN. In case of LPAE mode  XN(Execute-never) bit is not set with
DCACHE_OFF. Hence XN bit is not set by default for DCACHE_OFF which
keeps all the regions execute okay and this leads to random speculative
fetches in random memory regions which was eventually caught by kernel
omap-l3-noc driver.

Fix this to mark the regions as XN by default.

Signed-off-by: Keerthy <j-keerthy@ti.com>
Reviewed-by: Alexander Graf <agraf@suse.de>
Reviewed-by: Tom Rini <trini@konsulko.com>

arch/arm/include/asm/system.h

@@ -331,7 +331,7 @@ static inline void set_dacr(unsigned int val)
 
 /* options available for data cache on each page */
 enum dcache_option {
-	DCACHE_OFF = TTB_SECT | TTB_SECT_MAIR(0),
+	DCACHE_OFF = TTB_SECT | TTB_SECT_MAIR(0) | TTB_SECT_XN_MASK,
 	DCACHE_WRITETHROUGH = TTB_SECT | TTB_SECT_MAIR(1),
 	DCACHE_WRITEBACK = TTB_SECT | TTB_SECT_MAIR(2),
 	DCACHE_WRITEALLOC = TTB_SECT | TTB_SECT_MAIR(3),

arch/arm/lib/cache-cp15.c

@@ -71,8 +71,13 @@ void mmu_set_region_dcache_behaviour(phys_addr_t start, size_t size,
 
 	end = ALIGN(start + size, MMU_SECTION_SIZE) >> MMU_SECTION_SHIFT;
 	start = start >> MMU_SECTION_SHIFT;
+#ifdef CONFIG_ARMV7_LPAE
+	debug("%s: start=%pa, size=%zu, option=%llx\n", __func__, &start, size,
+	      option);
+#else
 	debug("%s: start=%pa, size=%zu, option=0x%x\n", __func__, &start, size,
 	      option);
+#endif
 	for (upto = start; upto < end; upto++)
 		set_section_dcache(upto, option);