RAS: Add fault injection support

The ARMv8.4 RAS extensions introduce architectural support for software
to inject faults into the system in order to test fault-handling
software. This patch introduces the build option FAULT_HANDLING_SUPPORT
to allow for lower ELs to use registers in the Standard Error Record to
inject fault. The build option RAS_EXTENSIONS must also be enabled along
with fault injection.

This feature is intended for testing purposes only, and is advisable to
keep disabled for production images.

Change-Id: I6f7a4454b15aec098f9505a10eb188c2f928f7ea
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>

Makefile

@@ -395,6 +395,13 @@ ifeq ($(RAS_EXTENSION),1)
     endif
 endif
 
+# When FAULT_INJECTION_SUPPORT is used, require that RAS_EXTENSION is enabled
+ifeq ($(FAULT_INJECTION_SUPPORT),1)
+    ifneq ($(RAS_EXTENSION),1)
+        $(error For FAULT_INJECTION_SUPPORT, RAS_EXTENSION must also be 1)
+    endif
+endif
+
 ################################################################################
 # Process platform overrideable behaviour
 ################################################################################
@@ -522,6 +529,7 @@ $(eval $(call assert_boolean,ENABLE_SPE_FOR_LOWER_ELS))
 $(eval $(call assert_boolean,ENABLE_SPM))
 $(eval $(call assert_boolean,ENABLE_SVE_FOR_NS))
 $(eval $(call assert_boolean,ERROR_DEPRECATED))
+$(eval $(call assert_boolean,FAULT_INJECTION_SUPPORT))
 $(eval $(call assert_boolean,GENERATE_COT))
 $(eval $(call assert_boolean,GICV2_G0_FOR_EL3))
 $(eval $(call assert_boolean,HANDLE_EA_EL3_FIRST))
@@ -571,6 +579,7 @@ $(eval $(call add_define,ENABLE_SPE_FOR_LOWER_ELS))
 $(eval $(call add_define,ENABLE_SPM))
 $(eval $(call add_define,ENABLE_SVE_FOR_NS))
 $(eval $(call add_define,ERROR_DEPRECATED))
+$(eval $(call add_define,FAULT_INJECTION_SUPPORT))
 $(eval $(call add_define,GICV2_G0_FOR_EL3))
 $(eval $(call add_define,HANDLE_EA_EL3_FIRST))
 $(eval $(call add_define,HW_ASSISTED_COHERENCY))

docs/user-guide.rst

@@ -390,6 +390,14 @@ Common build options
    handled at EL3, and a panic will result. This is supported only for AArch64
    builds.
 
+-  ``FAULT_INJECTION_SUPPORT``: ARMv8.4 externsions introduced support for fault
+   injection from lower ELs, and this build option enables lower ELs to use
+   Error Records accessed via System Registers to inject faults. This is
+   applicable only to AArch64 builds.
+
+   This feature is intended for testing purposes only, and is advisable to keep
+   disabled for production images.
+
 -  ``FIP_NAME``: This is an optional build option which specifies the FIP
    filename for the ``fip`` target. Default is ``fip.bin``.
 

include/lib/aarch64/arch.h

@@ -215,6 +215,7 @@
 
 /* SCR definitions */
 #define SCR_RES1_BITS		((U(1) << 4) | (U(1) << 5))
+#define SCR_FIEN_BIT		(U(1) << 21)
 #define SCR_TWE_BIT		(U(1) << 13)
 #define SCR_TWI_BIT		(U(1) << 12)
 #define SCR_ST_BIT		(U(1) << 11)

lib/el3_runtime/aarch64/context_mgmt.c

@@ -114,6 +114,11 @@ static void cm_init_context_common(cpu_context_t *ctx, const entry_point_info_t
 	scr_el3 &= ~SCR_EA_BIT;
 #endif
 
+#if FAULT_INJECTION_SUPPORT
+	/* Enable fault injection from lower ELs */
+	scr_el3 |= SCR_FIEN_BIT;
+#endif
+
 #ifdef IMAGE_BL31
 	/*
 	 * SCR_EL3.IRQ, SCR_EL3.FIQ: Enable the physical FIQ and IRQ rounting as

make_helpers/defaults.mk

@@ -76,6 +76,9 @@ EL3_EXCEPTION_HANDLING		:= 0
 # Build flag to treat usage of deprecated platform and framework APIs as error.
 ERROR_DEPRECATED		:= 0
 
+# Fault injection support
+FAULT_INJECTION_SUPPORT		:= 0
+
 # Byte alignment that each component in FIP is aligned to
 FIP_ALIGN			:= 0