target: aarch64: access reg SPSR_EL3 only in EL3

The register SPSR_EL3 is accessible and it's content is relevant
only when the target is in EL3.
Plus, the register is 64 bits wide.

Without this patch, an error:
	Error: Opcode 0xd53e4000, DSCR.ERR=1, DSCR.EL=1
is triggered by GDB register window or through GDB command
        x/p $SPSR_EL3
or through OpenOCD command
        reg SPSR_EL3

Detect the EL and return error if the register cannot be accessed.
Handle the register as 64 bits.

Change-Id: I00849d99feeb96589c426fcafda98127dbd19a67
Signed-off-by: Antonio Borneo <[email protected]>
Reviewed-on: https://review.openocd.org/c/openocd/+/8270
Tested-by: jenkins

src/target/armv8.c

@@ -361,9 +361,13 @@ static int armv8_read_reg(struct armv8_common *armv8, int regnum, uint64_t *regv
 		value_64 = value;
 		break;
 	case ARMV8_SPSR_EL3:
-		retval = dpm->instr_read_data_r0(dpm,
-				ARMV8_MRS(SYSTEM_SPSR_EL3, 0), &value);
-		value_64 = value;
+		if (curel < SYSTEM_CUREL_EL3) {
+			LOG_DEBUG("SPSR_EL3 not accessible in EL%u", curel);
+			retval = ERROR_FAIL;
+			break;
+		}
+		retval = dpm->instr_read_data_r0_64(dpm,
+				ARMV8_MRS(SYSTEM_SPSR_EL3, 0), &value_64);
 		break;
 	case ARMV8_PAUTH_CMASK:
 	case ARMV8_PAUTH_DMASK:
@@ -492,9 +496,13 @@ static int armv8_write_reg(struct armv8_common *armv8, int regnum, uint64_t valu
 				ARMV8_MSR_GP(SYSTEM_SPSR_EL2, 0), value);
 		break;
 	case ARMV8_SPSR_EL3:
-		value = value_64;
-		retval = dpm->instr_write_data_r0(dpm,
-				ARMV8_MSR_GP(SYSTEM_SPSR_EL3, 0), value);
+		if (curel < SYSTEM_CUREL_EL3) {
+			LOG_DEBUG("SPSR_EL3 not accessible in EL%u", curel);
+			retval = ERROR_FAIL;
+			break;
+		}
+		retval = dpm->instr_write_data_r0_64(dpm,
+				ARMV8_MSR_GP(SYSTEM_SPSR_EL3, 0), value_64);
 		break;
 	default:
 		retval = ERROR_FAIL;
@@ -1544,7 +1552,7 @@ static const struct {
 														NULL},
 	{ ARMV8_ESR_EL3, "ESR_EL3", 64, ARMV8_64_EL3H, REG_TYPE_UINT64, "banked", "net.sourceforge.openocd.banked",
 														NULL},
-	{ ARMV8_SPSR_EL3, "SPSR_EL3", 32, ARMV8_64_EL3H, REG_TYPE_UINT32, "banked", "net.sourceforge.openocd.banked",
+	{ ARMV8_SPSR_EL3, "SPSR_EL3", 64, ARMV8_64_EL3H, REG_TYPE_UINT64, "banked", "net.sourceforge.openocd.banked",
 														NULL},
 	{ ARMV8_PAUTH_DMASK, "pauth_dmask", 64, ARM_MODE_ANY, REG_TYPE_UINT64, NULL, "org.gnu.gdb.aarch64.pauth", NULL},
 	{ ARMV8_PAUTH_CMASK, "pauth_cmask", 64, ARM_MODE_ANY, REG_TYPE_UINT64, NULL, "org.gnu.gdb.aarch64.pauth", NULL},