feat(rme): run BL2 in root world when FEAT_RME is enabled
This patch enables BL2 to run in root world (EL3) which is
needed as per the security model of RME-enabled systems.
Using the existing BL2_AT_EL3 TF-A build option is not convenient
because that option assumes TF-A BL1 doesn't exist, which is not
the case for RME-enabled systems. For the purposes of RME, we use
a normal BL1 image but we also want to run BL2 in EL3 as normally as
possible, therefore rather than use the special bl2_entrypoint
function in bl2_el3_entrypoint.S, we use a new bl2_entrypoint
function (in bl2_rme_entrypoint.S) which doesn't need reset or
mailbox initialization code seen in the el3_entrypoint_common macro.
The patch also cleans up bl2_el3_entrypoint.S, moving the
bl2_run_next_image function to its own file to avoid duplicating
code.
Signed-off-by: Zelalem Aweke <zelalem.aweke@arm.com>
Change-Id: I99821b4cd550cadcb701f4c0c4dc36da81c7ef55
diff --git a/bl1/aarch64/bl1_entrypoint.S b/bl1/aarch64/bl1_entrypoint.S
index 00f2718..f61c060 100644
--- a/bl1/aarch64/bl1_entrypoint.S
+++ b/bl1/aarch64/bl1_entrypoint.S
@@ -1,13 +1,15 @@
/*
- * Copyright (c) 2013-2019, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2013-2021, Arm Limited and Contributors. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include <arch.h>
+#include <common/bl_common.h>
#include <el3_common_macros.S>
.globl bl1_entrypoint
+ .globl bl1_run_bl2_in_root
/* -----------------------------------------------------
@@ -66,5 +68,41 @@
* Do the transition to next boot image.
* --------------------------------------------------
*/
+#if ENABLE_RME
+ b bl1_run_bl2_in_root
+#else
b el3_exit
+#endif
endfunc bl1_entrypoint
+
+ /* -----------------------------------------------------
+ * void bl1_run_bl2_in_root();
+ * This function runs BL2 in root/EL3 when RME is enabled.
+ * -----------------------------------------------------
+ */
+
+func bl1_run_bl2_in_root
+ /* read bl2_ep_info */
+ adrp x20, bl2_ep_info
+ add x20, x20, :lo12:bl2_ep_info
+ ldr x20, [x20]
+
+ /* ---------------------------------------------
+ * MMU needs to be disabled because BL2 executes
+ * in EL3. It will initialize the address space
+ * according to its own requirements.
+ * ---------------------------------------------
+ */
+ bl disable_mmu_icache_el3
+ tlbi alle3
+
+ ldp x0, x1, [x20, #ENTRY_POINT_INFO_PC_OFFSET]
+ msr elr_el3, x0
+ msr spsr_el3, x1
+
+ ldp x6, x7, [x20, #(ENTRY_POINT_INFO_ARGS_OFFSET + 0x30)]
+ ldp x4, x5, [x20, #(ENTRY_POINT_INFO_ARGS_OFFSET + 0x20)]
+ ldp x2, x3, [x20, #(ENTRY_POINT_INFO_ARGS_OFFSET + 0x10)]
+ ldp x0, x1, [x20, #(ENTRY_POINT_INFO_ARGS_OFFSET + 0x0)]
+ exception_return
+endfunc bl1_run_bl2_in_root