Introduce SPIN_ON_BL1_EXIT build flag
This patch introduces a new build flag, SPIN_ON_BL1_EXIT, which
puts an infinite loop in BL1. It is intended to help debugging
the post-BL2 phase of the Trusted Firmware by stopping execution
in BL1 just before handing over to BL31. At this point, the
developer may take control of the target using a debugger.
This feature is disabled by default and can be enabled by
rebuilding BL1 with SPIN_ON_BL1_EXIT=1.
User Guide updated accordingly.
Change-Id: I6b6779d5949c9e5571dd371255520ef1ac39685c
diff --git a/Makefile b/Makefile
index 7a4be44..c3252c2 100644
--- a/Makefile
+++ b/Makefile
@@ -89,6 +89,9 @@
PROGRAMMABLE_RESET_ADDRESS := 0
# Build flag to treat usage of deprecated platform and framework APIs as error.
ERROR_DEPRECATED := 0
+# Flag to introduce an infinite loop in BL1 just before it exits into the next
+# image. This is meant to help debugging the post-BL2 phase.
+SPIN_ON_BL1_EXIT := 0
################################################################################
@@ -348,6 +351,7 @@
$(eval $(call assert_boolean,PSCI_EXTENDED_STATE_ID))
$(eval $(call assert_boolean,ERROR_DEPRECATED))
$(eval $(call assert_boolean,ENABLE_PLAT_COMPAT))
+$(eval $(call assert_boolean,SPIN_ON_BL1_EXIT))
################################################################################
@@ -370,6 +374,7 @@
$(eval $(call add_define,PSCI_EXTENDED_STATE_ID))
$(eval $(call add_define,ERROR_DEPRECATED))
$(eval $(call add_define,ENABLE_PLAT_COMPAT))
+$(eval $(call add_define,SPIN_ON_BL1_EXIT))
################################################################################
diff --git a/bl1/aarch64/bl1_exceptions.S b/bl1/aarch64/bl1_exceptions.S
index 0bd0485..ee66ef0 100644
--- a/bl1/aarch64/bl1_exceptions.S
+++ b/bl1/aarch64/bl1_exceptions.S
@@ -207,6 +207,12 @@
bl disable_mmu_icache_el3
tlbi alle3
+#if SPIN_ON_BL1_EXIT
+ bl print_debug_loop_message
+debug_loop:
+ b debug_loop
+#endif
+
bl bl1_plat_prepare_exit
ldp x6, x7, [x20, #(ENTRY_POINT_INFO_ARGS_OFFSET + 0x30)]
diff --git a/bl1/bl1_main.c b/bl1/bl1_main.c
index f62f31d..73f023a 100644
--- a/bl1/bl1_main.c
+++ b/bl1/bl1_main.c
@@ -208,3 +208,11 @@
NOTICE("BL1: Booting BL3-1\n");
print_entry_point_info(bl31_ep_info);
}
+
+#if SPIN_ON_BL1_EXIT
+void print_debug_loop_message(void)
+{
+ NOTICE("BL1: Debug loop, spinning forever\n");
+ NOTICE("BL1: Please connect the debugger to continue\n");
+}
+#endif
diff --git a/docs/user-guide.md b/docs/user-guide.md
index a7a0c11..3db7a86 100644
--- a/docs/user-guide.md
+++ b/docs/user-guide.md
@@ -372,6 +372,12 @@
Firmware as error. It can take the value 1 (flag the use of deprecated
APIs as error) or 0. The default is 0.
+* `SPIN_ON_BL1_EXIT`: This option introduces an infinite loop in BL1. It can
+ take either 0 (no loop) or 1 (add a loop). 0 is the default. This loop stops
+ execution in BL1 just before handing over to BL31. At this point, all
+ firmware images have been loaded in memory and the MMU as well as the caches
+ are turned off. Refer to the "Debugging options" section for more details.
+
#### ARM development platform specific build options
* `ARM_TSP_RAM_LOCATION`: location of the TSP binary. Options:
@@ -500,6 +506,25 @@
BL33=<path-to>/<bl33_image> \
make PLAT=<platform> DEBUG=1 V=1 all fip
+It is also possible to introduce an infinite loop to help in debugging the
+post-BL2 phase of the Trusted Firmware. This can be done by rebuilding BL1 with
+the `SPIN_ON_BL1_EXIT=1` build flag. Refer to the "Summary of build options"
+section. In this case, the developer may take control of the target using a
+debugger when indicated by the console output. When using DS-5, the following
+commands can be used:
+
+ # Stop target execution
+ interrupt
+
+ #
+ # Prepare your debugging environment, e.g. set breakpoints
+ #
+
+ # Jump over the debug loop
+ set var $AARCH64::$Core::$PC = $AARCH64::$Core::$PC + 4
+
+ # Resume execution
+ continue
### Building the Test Secure Payload