FVP: Do not map DEVICE2 memory range when TBB is disabled

The DEVICE2 memory range is needed to access the Root of Trust Public
Key registers. This is not needed when Trusted Board Boot is disabled
so it's safer to not map it in this case. This also saves one level-2
page table in each of BL1 and BL2 images.

Also add some comments.

Change-Id: I67456b44f3fd5e145f6510a8499b7fdf720a7273
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>

diff --git a/plat/arm/board/common/board_css_common.c b/plat/arm/board/common/board_css_common.c
index 42f754e25af2aa2008ebd2020994e4869983be56..f6a554f324199d64aa229b546cd6445735cddcf2 100644 (file)
--- a/plat/arm/board/common/board_css_common.c
+++ b/plat/arm/board/common/board_css_common.c
@@ -19,6 +19,7 @@ const mmap_region_t plat_arm_mmap[] = {
        CSS_MAP_DEVICE,
        SOC_CSS_MAP_DEVICE,
 #if TRUSTED_BOARD_BOOT
+       /* Map DRAM to authenticate NS_BL2U image. */
        ARM_MAP_NS_DRAM1,
 #endif
        {0}

diff --git a/plat/arm/board/fvp/fvp_common.c b/plat/arm/board/fvp/fvp_common.c
index eb37f113ad35ada648155ff6127c61a722e8c4c3..2f5d7fcf5f64407ab8d13c50e695aaacfeef2d90 100644 (file)
--- a/plat/arm/board/fvp/fvp_common.c
+++ b/plat/arm/board/fvp/fvp_common.c
@@ -36,6 +36,10 @@ arm_config_t arm_config;
                                        DEVICE1_SIZE,                   \
                                        MT_DEVICE | MT_RW | MT_SECURE)
 
+/*
+ * Need to be mapped with write permissions in order to set a new non-volatile
+ * counter value.
+ */
 #define MAP_DEVICE2    MAP_REGION_FLAT(DEVICE2_BASE,                   \
                                        DEVICE2_SIZE,                   \
                                        MT_DEVICE | MT_RW | MT_SECURE)
@@ -56,8 +60,10 @@ const mmap_region_t plat_arm_mmap[] = {
        V2M_MAP_IOFPGA,
        MAP_DEVICE0,
        MAP_DEVICE1,
-       MAP_DEVICE2,
 #if TRUSTED_BOARD_BOOT
+       /* To access the Root of Trust Public Key registers. */
+       MAP_DEVICE2,
+       /* Map DRAM to authenticate NS_BL2U image. */
        ARM_MAP_NS_DRAM1,
 #endif
        {0}
@@ -70,9 +76,12 @@ const mmap_region_t plat_arm_mmap[] = {
        V2M_MAP_IOFPGA,
        MAP_DEVICE0,
        MAP_DEVICE1,
-       MAP_DEVICE2,
        ARM_MAP_NS_DRAM1,
        ARM_MAP_TSP_SEC_MEM,
+#if TRUSTED_BOARD_BOOT
+       /* To access the Root of Trust Public Key registers. */
+       MAP_DEVICE2,
+#endif
 #if ARM_BL31_IN_DRAM
        ARM_MAP_BL31_SEC_DRAM,
 #endif