[PATCH] arm: mach-imx: Fix speculative instruction prefetch issue

[Ye Li]

Default ARM32 MMU setting in u-boot sets XN bit to entire 4GB space no
matter which DCACHE option is used, and set domain permission to manager.
This causes MMU ignores the access check and XN bit, so speculative
instruction can fetch from entire space.

This patch sets the DDR, ROM, OCRAM without XN bit, and set domain to client
to enable the XN and access check. So speculative instruction fetch can only
happens on these 3 regions to avoid prefetch from peripherals and invalid
regions.

Signed-off-by: Ye Li <ye.li at nxp.com>
Reviewed-by: Peng Fan <peng.fan at nxp.com>
---
 arch/arm/mach-imx/cache.c | 49 ++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 42 insertions(+), 7 deletions(-)

diff --git a/arch/arm/mach-imx/cache.c b/arch/arm/mach-imx/cache.c
index 4e3b49a..8486c2d 100644
--- a/arch/arm/mach-imx/cache.c
+++ b/arch/arm/mach-imx/cache.c
@@ -10,6 +10,10 @@
 #include <asm/pl310.h>
 #include <asm/io.h>
 #include <asm/mach-imx/sys_proto.h>
+#include <asm/global_data.h>
+#include <log.h>
+
+DECLARE_GLOBAL_DATA_PTR;
 
 static void enable_ca7_smp(void)
 {
@@ -40,13 +44,13 @@ static void enable_ca7_smp(void)
 }
 
 #if !CONFIG_IS_ENABLED(SYS_DCACHE_OFF)
+
+#define ARMV7_DOMAIN_CLIENT	1
+#define ARMV7_DOMAIN_MASK	(0x3 << 0)
+#define IMX_ARMV7_DCACHE_OPTION (DCACHE_DEFAULT_OPTION & ~TTB_SECT_XN_MASK)
+
 void enable_caches(void)
 {
-#if defined(CONFIG_SYS_ARM_CACHE_WRITETHROUGH)
-	enum dcache_option option = DCACHE_WRITETHROUGH;
-#else
-	enum dcache_option option = DCACHE_WRITEBACK;
-#endif
 	/* Avoid random hang when download by usb */
 	invalidate_dcache_all();
 
@@ -59,11 +63,42 @@ void enable_caches(void)
 	/* Enable caching on OCRAM and ROM */
 	mmu_set_region_dcache_behaviour(ROMCP_ARB_BASE_ADDR,
 					ROMCP_ARB_END_ADDR,
-					option);
+					IMX_ARMV7_DCACHE_OPTION);
 	mmu_set_region_dcache_behaviour(IRAM_BASE_ADDR,
 					IRAM_SIZE,
-					option);
+					IMX_ARMV7_DCACHE_OPTION);
+}
+
+void dram_bank_mmu_setup(int bank)
+{
+	struct bd_info *bd = gd->bd;
+	int	i;
+
+	/* bd->bi_dram is available only after relocation */
+	if ((gd->flags & GD_FLG_RELOC) == 0)
+		return;
+
+	debug("%s: bank: %d\n", __func__, bank);
+	for (i = bd->bi_dram[bank].start >> MMU_SECTION_SHIFT;
+	     i < (bd->bi_dram[bank].start >> MMU_SECTION_SHIFT) +
+		 (bd->bi_dram[bank].size >> MMU_SECTION_SHIFT);
+	     i++)
+		set_section_dcache(i, IMX_ARMV7_DCACHE_OPTION);
 }
+
+void arm_init_domains(void)
+{
+	u32 reg;
+
+	reg = get_dacr();
+	/*
+	* Set domain to client to do access and XN check
+	*/
+	reg &= ~ARMV7_DOMAIN_MASK;
+	reg |= ARMV7_DOMAIN_CLIENT;
+	set_dacr(reg);
+}
+
 #else
 void enable_caches(void)
 {
-- 
2.7.4