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/bl2/aarch64/bl2_rme_entrypoint.S b/bl2/aarch64/bl2_rme_entrypoint.S
new file mode 100644
index 0000000..076e326
--- /dev/null
+++ b/bl2/aarch64/bl2_rme_entrypoint.S
@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2021, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <platform_def.h>
+
+#include <arch.h>
+#include <asm_macros.S>
+#include <common/bl_common.h>
+#include <el3_common_macros.S>
+
+ .globl bl2_entrypoint
+
+
+func bl2_entrypoint
+ /* Save arguments x0-x3 from previous Boot loader */
+ mov x20, x0
+ mov x21, x1
+ mov x22, x2
+ mov x23, x3
+
+ el3_entrypoint_common \
+ _init_sctlr=0 \
+ _warm_boot_mailbox=0 \
+ _secondary_cold_boot=0 \
+ _init_memory=0 \
+ _init_c_runtime=1 \
+ _exception_vectors=bl2_el3_exceptions \
+ _pie_fixup_size=0
+
+ /* ---------------------------------------------
+ * Restore parameters of boot rom
+ * ---------------------------------------------
+ */
+ mov x0, x20
+ mov x1, x21
+ mov x2, x22
+ mov x3, x23
+
+ /* ---------------------------------------------
+ * Perform BL2 setup
+ * ---------------------------------------------
+ */
+ bl bl2_setup
+
+#if ENABLE_PAUTH
+ /* ---------------------------------------------
+ * Program APIAKey_EL1 and enable pointer authentication.
+ * ---------------------------------------------
+ */
+ bl pauth_init_enable_el3
+#endif /* ENABLE_PAUTH */
+
+ /* ---------------------------------------------
+ * Jump to main function.
+ * ---------------------------------------------
+ */
+ bl bl2_main
+
+ /* ---------------------------------------------
+ * Should never reach this point.
+ * ---------------------------------------------
+ */
+ no_ret plat_panic_handler
+endfunc bl2_entrypoint