Add support for BL3-2 in BL3-1

This patch adds the following support to the BL3-1 stage:

1. BL3-1 allows runtime services to specify and determine the security
   state of the next image after BL3-1. This has been done by adding
   the `bl31_set_next_image_type()` & `bl31_get_next_image_type()`
   apis. The default security state is non-secure. The platform api
   `bl31_get_next_image_info()` has been modified to let the platform
   decide which is the next image in the desired security state.

2. BL3-1 exports the `bl31_prepare_next_image_entry()` function to
   program entry into the target security state. It uses the apis
   introduced in 1. to do so.

3. BL3-1 reads the information populated by BL2 about the BL3-2 image
   into its internal data structures.

4. BL3-1 introduces a weakly defined reference `bl32_init()` to allow
   initialisation of a BL3-2 image. A runtime service like the Secure
   payload dispatcher will define this function if present.

Change-Id: Icc46dcdb9e475ce6575dd3f9a5dc7a48a83d21d1

1 files changed, 82 insertions, 10 deletions

diff --git a/bl31/bl31_main.c b/bl31/bl31_main.c
index 9d2dc299..ea44871c 100644
--- a/bl31/bl31_main.c
+++ b/bl31/bl31_main.c
@@ -41,6 +41,12 @@
 #include <context_mgmt.h>
 
 /*******************************************************************************
+ * Variable to indicate whether next image to execute after BL31 is BL33
+ * (non-secure & default) or BL32 (secure).
+ ******************************************************************************/
+static uint32_t next_image_type = NON_SECURE;
+
+/*******************************************************************************
  * Simple function to initialise all BL31 helper libraries.
  ******************************************************************************/
 void bl31_lib_init()
@@ -50,16 +56,17 @@ void bl31_lib_init()
 
 /*******************************************************************************
  * BL31 is responsible for setting up the runtime services for the primary cpu
- * before passing control to the bootloader (UEFI) or Linux. This function calls
- * runtime_svc_init() which initializes all registered runtime services. The run
- * time services would setup enough context for the core to swtich to the next
- * exception level. When this function returns, the core will switch to the
- * programmed exception level via. an ERET.
+ * before passing control to the bootloader or an Operating System. This
+ * function calls runtime_svc_init() which initializes all registered runtime
+ * services. The run time services would setup enough context for the core to
+ * swtich to the next exception level. When this function returns, the core will
+ * switch to the programmed exception level via. an ERET.
  ******************************************************************************/
 void bl31_main(void)
 {
-	el_change_info *next_image_info;
-	uint32_t scr;
+#if DEBUG
+	unsigned long mpidr = read_mpidr();
+#endif
 
 	/* Perform remaining generic architectural setup from EL3 */
 	bl31_arch_setup();
@@ -80,15 +87,80 @@ void bl31_main(void)
 	dcsw_op_all(DCCSW);
 
 	/*
+	 * Use the more complex exception vectors now that context
+	 * management is setup. SP_EL3 should point to a 'cpu_context'
+	 * structure which has an exception stack allocated.  The PSCI
+	 * service should have set the context.
+	 */
+	assert(cm_get_context(mpidr, NON_SECURE));
+	cm_set_next_eret_context(NON_SECURE);
+	write_vbar_el3((uint64_t) runtime_exceptions);
+
+	/*
+	 * All the cold boot actions on the primary cpu are done. We
+	 * now need to decide which is the next image (BL32 or BL33)
+	 * and how to execute it. If the SPD runtime service is
+	 * present, it would want to pass control to BL32 first in
+	 * S-EL1. It will export the bl32_init() routine where it takes
+	 * responsibility of entering S-EL1 and returning control back
+	 * to bl31_main. Once this is done we can prepare entry into
+	 * BL33 as normal.
+	 */
+
+	/* Tell BL32 about it memory extents as well */
+	if (bl32_init)
+		bl32_init(bl31_plat_get_bl32_mem_layout());
+
+	/*
+	 * We are ready to enter the next EL. Prepare entry into the image
+	 * corresponding to the desired security state after the next ERET.
+	 */
+	bl31_prepare_next_image_entry();
+}
+
+/*******************************************************************************
+ * Accessor functions to help runtime services decide which image should be
+ * executed after BL31. This is BL33 or the non-secure bootloader image by
+ * default but the Secure payload dispatcher could override this by requesting
+ * an entry into BL32 (Secure payload) first. If it does so then it should use
+ * the same API to program an entry into BL33 once BL32 initialisation is
+ * complete.
+ ******************************************************************************/
+void bl31_set_next_image_type(uint32_t security_state)
+{
+	assert(security_state == NON_SECURE || security_state == SECURE);
+	next_image_type = security_state;
+}
+
+uint32_t bl31_get_next_image_type(void)
+{
+	return next_image_type;
+}
+
+/*******************************************************************************
+ * This function programs EL3 registers and performs other setup to enable entry
+ * into the next image after BL31 at the next ERET.
+ ******************************************************************************/
+void bl31_prepare_next_image_entry()
+{
+	el_change_info *next_image_info;
+	uint32_t scr, image_type;
+
+	/* Determine which image to execute next */
+	image_type = bl31_get_next_image_type();
+
+	/*
 	 * Setup minimal architectural state of the next highest EL to
 	 * allow execution in it immediately upon entering it.
 	 */
-	bl31_arch_next_el_setup();
+	bl31_next_el_arch_setup(image_type);
 
 	/* Program EL3 registers to enable entry into the next EL */
-	next_image_info = bl31_get_next_image_info();
+	next_image_info = bl31_get_next_image_info(image_type);
+	assert(next_image_info);
+
 	scr = read_scr();
-	if (next_image_info->security_state == NON_SECURE)
+	if (image_type == NON_SECURE)
 		scr |= SCR_NS_BIT;
 
 	/*