feat(ls64): add LS64_ACCDATA test

FEAT_LS64_ACCDATA introduces the system register ACCDATA_EL1, its value
replacing the first four bytes of the data provided to an ST64BV0
instruction. As this system register would need context switching
between non-secure and secure worlds, there is an SCR_EL3 bit to allow
trapping accesses from lower ELs into EL3.

Introduce a check to verify that accesses to this system register do not
trap into EL3, if the CPUID registers advertise this feature.
Bits[63:32] of ACCDATA_EL1 are described as RES0, so mask those bits
when comparing the read-back values with the written one.

Change-Id: Ia32bcf7187356c701470a1757708b3d554e88629
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
diff --git a/include/common/test_helpers.h b/include/common/test_helpers.h
index d6a7ade..28b1d4e 100644
--- a/include/common/test_helpers.h
+++ b/include/common/test_helpers.h
@@ -355,6 +355,15 @@
 		}								\
 	} while (false)
 
+#define SKIP_TEST_IF_LS64_ACCDATA_NOT_SUPPORTED()			\
+	do {								\
+		if (get_feat_ls64_support() <				\
+		    ID_AA64ISAR1_LS64_ACCDATA_SUPPORTED) {		\
+			tftf_testcase_printf("ARMv8.7-ls64-accdata not supported");	\
+			return TEST_RESULT_SKIPPED;			\
+		}							\
+	} while (false)
+
 /* Helper macro to verify if system suspend API is supported */
 #define is_psci_sys_susp_supported()	\
 		(tftf_get_psci_feature_info(SMC_PSCI_SYSTEM_SUSPEND)		\
diff --git a/include/lib/aarch64/arch.h b/include/lib/aarch64/arch.h
index a1dca21..a641052 100644
--- a/include/lib/aarch64/arch.h
+++ b/include/lib/aarch64/arch.h
@@ -1323,6 +1323,11 @@
  ******************************************************************************/
 #define CNTPOFF_EL2  S3_4_C14_C0_6
 
+/*******************************************************************************
+ * Armv8.7 - LoadStore64Bytes Registers
+ ******************************************************************************/
+#define SYS_ACCDATA_EL1		S3_0_C13_C0_5
+
 /******************************************************************************
  * Armv8.9 - Breakpoint and Watchpoint Selection Register
  ******************************************************************************/
diff --git a/include/lib/aarch64/arch_helpers.h b/include/lib/aarch64/arch_helpers.h
index 455ae27..744bbe6 100644
--- a/include/lib/aarch64/arch_helpers.h
+++ b/include/lib/aarch64/arch_helpers.h
@@ -230,6 +230,8 @@
 DEFINE_SYSOP_PARAM_FUNC(wfit)
 DEFINE_SYSOP_PARAM_FUNC(wfet)
 
+DEFINE_RENAME_SYSREG_RW_FUNCS(sys_accdata_el1, SYS_ACCDATA_EL1)
+
 static inline void enable_irq(void)
 {
 	/*
diff --git a/tftf/tests/extensions/ls64/test_ls64.c b/tftf/tests/extensions/ls64/test_ls64.c
index b7074ab..1f2fad7 100644
--- a/tftf/tests/extensions/ls64/test_ls64.c
+++ b/tftf/tests/extensions/ls64/test_ls64.c
@@ -64,7 +64,6 @@
 
 	return TEST_RESULT_SUCCESS;
 #else
-	/* Skip test if AArch32 */
 	SKIP_TEST_IF_AARCH32();
 #endif /* __aarch64_ */
 #else
@@ -73,3 +72,28 @@
 #endif /* PLAT_fvp */
 
 }
+
+/*
+ * @brief Test LS64_ACCDATA feature support when the extension is enabled.
+ *
+ * Write to the ACCDATA_EL1 system register, and read it back. This is
+ * primarily to see if accesses to this register trap to EL3 (they should not).
+ *
+ * @return test_result_t
+ */
+test_result_t test_ls64_accdata_sysreg(void)
+{
+#ifdef __aarch64__
+	SKIP_TEST_IF_LS64_ACCDATA_NOT_SUPPORTED();
+
+	write_sys_accdata_el1(0x1234567890);
+	if ((read_sys_accdata_el1() & 0xffffffff) != 0x34567890) {
+		NOTICE("SYS_ACCDATA_EL1: 0x%lx\n", read_sys_accdata_el1());
+		return TEST_RESULT_FAIL;
+	}
+
+	return TEST_RESULT_SUCCESS;
+#else
+	SKIP_TEST_IF_AARCH32();
+#endif /* __aarch64_ */
+}
diff --git a/tftf/tests/tests-cpu-extensions.xml b/tftf/tests/tests-cpu-extensions.xml
index 62bb9ea..34ac0b6 100644
--- a/tftf/tests/tests-cpu-extensions.xml
+++ b/tftf/tests/tests-cpu-extensions.xml
@@ -38,6 +38,7 @@
     <testcase name="PMUv3 event counter functional in NS" function="test_pmuv3_event_works_ns" />
     <testcase name="PMUv3 SMC counter preservation" function="test_pmuv3_el3_preserves" />
     <testcase name="LS64 support" function="test_ls64_instructions" />
+    <testcase name="LS64-ACCDATA support" function="test_ls64_accdata_sysreg" />
   </testsuite>
 
   <testsuite name="ARM_ARCH_SVC" description="Arm Architecture Service tests">