CSS: Enable booting of EL3 payloads
This patch adds support for booting EL3 payloads on CSS platforms,
for example Juno. In this scenario, the Trusted Firmware follows
its normal boot flow up to the point where it would normally pass
control to the BL31 image. At this point, it jumps to the EL3
payload entry point address instead.
Before handing over to the EL3 payload, the data SCP writes for AP
at the beginning of the Trusted SRAM is restored, i.e. we zero the
first 128 bytes and restore the SCP Boot configuration. The latter
is saved before transferring the BL30 image to SCP and is restored
just after the transfer (in BL2). The goal is to make it appear that
the EL3 payload is the first piece of software to run on the target.
The BL31 entrypoint info structure is updated to make the primary
CPU jump to the EL3 payload instead of the BL31 image.
The mailbox is populated with the EL3 payload entrypoint address,
which releases the secondary CPUs out of their holding pen (if the
SCP has powered them on). The arm_program_trusted_mailbox() function
has been exported for this purpose.
The TZC-400 configuration in BL2 is simplified: it grants secure
access only to the whole DRAM. Other security initialization is
unchanged.
This alternative boot flow is disabled by default. A new build option
EL3_PAYLOAD_BASE has been introduced to enable it and provide the EL3
payload's entry point address. The build system has been modified
such that BL31 and BL33 are not compiled and/or not put in the FIP in
this case, as those images are not used in this boot flow.
Change-Id: Id2e26fa57988bbc32323a0effd022ab42f5b5077
diff --git a/Makefile b/Makefile
index c3252c2..80e05fa 100644
--- a/Makefile
+++ b/Makefile
@@ -235,6 +235,10 @@
################################################################################
ifneq (${SPD},none)
+ifdef EL3_PAYLOAD_BASE
+ $(warning "SPD and EL3_PAYLOAD_BASE are incompatible build options.")
+ $(warning "The SPD and its BL32 companion will be present but ignored.")
+endif
# We expect to locate an spd.mk under the specified SPD directory
SPD_MAKE := $(shell m="services/spd/${SPD}/${SPD}.mk"; [ -f "$$m" ] && echo "$$m")
@@ -300,7 +304,12 @@
# supplied for the FIP and Certificate generation tools. This flag can be
# overridden by the platform.
ifdef BL2_SOURCES
+ifndef EL3_PAYLOAD_BASE
NEED_BL33 ?= yes
+else
+# The BL33 image is not needed when booting an EL3 payload.
+NEED_BL33 := no
+endif
endif
# Process TBB related flags
@@ -375,6 +384,10 @@
$(eval $(call add_define,ERROR_DEPRECATED))
$(eval $(call add_define,ENABLE_PLAT_COMPAT))
$(eval $(call add_define,SPIN_ON_BL1_EXIT))
+# Define the EL3_PAYLOAD_BASE flag only if it is provided.
+ifdef EL3_PAYLOAD_BASE
+$(eval $(call add_define,EL3_PAYLOAD_BASE))
+endif
################################################################################
@@ -392,9 +405,13 @@
endif
ifdef BL31_SOURCES
+# When booting an EL3 payload, there is no need to compile the BL31 image nor
+# put it in the FIP.
+ifndef EL3_PAYLOAD_BASE
NEED_BL31 := yes
include bl31/bl31.mk
endif
+endif
################################################################################