Merge pull request #415 from jcastillo-arm/jc/plat_err_handler

Add optional platform error handler API

bl1/bl1_main.c

@@ -174,12 +174,8 @@ void bl1_main(void)
 			 &bl2_ep);
 
 	if (err) {
-		/*
-		 * TODO: print failure to load BL2 but also add a tzwdog timer
-		 * which will reset the system eventually.
-		 */
 		ERROR("Failed to load BL2 firmware.\n");
-		panic();
+		plat_error_handler(err);
 	}
 
 	/*

bl2/bl2_main.c

@@ -219,7 +219,7 @@ void bl2_main(void)
 	e = load_bl30();
 	if (e) {
 		ERROR("Failed to load BL3-0 (%i)\n", e);
-		panic();
+		plat_error_handler(e);
 	}
 
 	/* Perform platform setup in BL2 after loading BL3-0 */
@@ -235,14 +235,14 @@ void bl2_main(void)
 	e = load_bl31(bl2_to_bl31_params, bl31_ep_info);
 	if (e) {
 		ERROR("Failed to load BL3-1 (%i)\n", e);
-		panic();
+		plat_error_handler(e);
 	}
 
 	e = load_bl32(bl2_to_bl31_params);
 	if (e) {
 		if (e == -EAUTH) {
 			ERROR("Failed to authenticate BL3-2\n");
-			panic();
+			plat_error_handler(e);
 		} else {
 			WARN("Failed to load BL3-2 (%i)\n", e);
 		}
@@ -251,7 +251,7 @@ void bl2_main(void)
 	e = load_bl33(bl2_to_bl31_params);
 	if (e) {
 		ERROR("Failed to load BL3-3 (%i)\n", e);
-		panic();
+		plat_error_handler(e);
 	}
 
 	/* Flush the params to be passed to memory */

docs/porting-guide.md

@@ -650,6 +650,27 @@ it has restrictions for stack usage and it can use the registers x0 - x17 as
 scratch registers. It should preserve the value in x18 register as it is used
 by the caller to store the return address.
 
+### Function : plat_error_handler()
+
+    Argument : int
+    Return   : void
+
+This API is called when the generic code encounters an error situation from
+which it cannot continue. It allows the platform to perform error reporting or
+recovery actions (for example, reset the system). This function must not return.
+
+The parameter indicates the type of error using standard codes from `errno.h`.
+Possible errors reported by the generic code are:
+
+*   `-EAUTH`: a certificate or image could not be authenticated (when Trusted
+    Board Boot is enabled)
+*   `-ENOENT`: the requested image or certificate could not be found or an IO
+    error was detected
+*   `-ENOMEM`: resources exhausted. Trusted Firmware does not use dynamic
+    memory, so this error is usually an indication of an incorrect array size
+
+The default implementation simply spins.
+
 
 3.  Modifications specific to a Boot Loader stage
 -------------------------------------------------

include/plat/common/platform.h

@@ -81,6 +81,7 @@ unsigned long plat_get_my_stack(void);
 void plat_report_exception(unsigned long);
 int plat_crash_console_init(void);
 int plat_crash_console_putc(int c);
+void plat_error_handler(int err) __dead2;
 
 /*******************************************************************************
  * Mandatory BL1 functions

plat/common/aarch64/platform_helpers.S

@@ -38,6 +38,7 @@
 	.weak	plat_reset_handler
 	.weak	plat_disable_acp
 	.weak	bl1_plat_prepare_exit
+	.weak	plat_error_handler
 
 #if !ENABLE_PLAT_COMPAT
 	.globl	platform_get_core_pos
@@ -121,3 +122,12 @@ endfunc plat_disable_acp
 func bl1_plat_prepare_exit
 	ret
 endfunc bl1_plat_prepare_exit
+
+	/* -----------------------------------------------------
+	 * void plat_error_handler(int err) __dead2;
+	 * Endless loop by default.
+	 * -----------------------------------------------------
+	 */
+func plat_error_handler
+	b	plat_error_handler
+endfunc plat_error_handler