X-Git-Url: https://review.openocd.org/gitweb?a=blobdiff_plain;f=src%2Ftarget%2Farmv8_dpm.c;h=081eed21ba21166ef5babadd78b9537f9a36dde8;hb=8795090edcf7b83e65f07941b0186c63a358c31a;hp=4bb20755f3b631756fcd54d715f0d70a6fb3f20c;hpb=ef263a45a272366836da10b7c42c916d43527f86;p=openocd.git

diff --git a/src/target/armv8_dpm.c b/src/target/armv8_dpm.c
index 4bb20755f3..081eed21ba 100644
--- a/src/target/armv8_dpm.c
+++ b/src/target/armv8_dpm.c
@@ -28,6 +28,8 @@
 
 #include "helper/time_support.h"
 
+/* T32 ITR format */
+#define T32_FMTITR(instr) (((instr & 0x0000FFFF) << 16) | ((instr & 0xFFFF0000) >> 16))
 
 /**
  * @file
@@ -42,11 +44,27 @@
  * to minimize needless differences in debug behavior between cores.
  */
 
+/**
+ * Get core state from EDSCR, without necessity to retrieve CPSR
+ */
+enum arm_state armv8_dpm_get_core_state(struct arm_dpm *dpm)
+{
+	int el = (dpm->dscr >> 8) & 0x3;
+	int rw = (dpm->dscr >> 10) & 0xF;
+
+	dpm->last_el = el;
+
+	/* In Debug state, each bit gives the current Execution state of each EL */
+	if ((rw >> el) & 0b1)
+		return ARM_STATE_AARCH64;
+
+	return ARM_STATE_ARM;
+}
+
 /*----------------------------------------------------------------------*/
 
 static int dpmv8_write_dcc(struct armv8_common *armv8, uint32_t data)
 {
-	LOG_DEBUG("write DCC 0x%08" PRIx32, data);
 	return mem_ap_write_u32(armv8->debug_ap,
 				armv8->debug_base + CPUV8_DBG_DTRRX, data);
 }
@@ -54,11 +72,10 @@ static int dpmv8_write_dcc(struct armv8_common *armv8, uint32_t data)
 static int dpmv8_write_dcc_64(struct armv8_common *armv8, uint64_t data)
 {
 	int ret;
-	LOG_DEBUG("write DCC Low word 0x%08" PRIx32, (unsigned)data);
-	LOG_DEBUG("write DCC High word 0x%08" PRIx32, (unsigned)(data >> 32));
 	ret = mem_ap_write_u32(armv8->debug_ap,
 			       armv8->debug_base + CPUV8_DBG_DTRRX, data);
-	ret += mem_ap_write_u32(armv8->debug_ap,
+	if (ret == ERROR_OK)
+		ret = mem_ap_write_u32(armv8->debug_ap,
 				armv8->debug_base + CPUV8_DBG_DTRTX, data >> 32);
 	return ret;
 }
@@ -91,7 +108,6 @@ static int dpmv8_read_dcc(struct armv8_common *armv8, uint32_t *data,
 					    data);
 	if (retval != ERROR_OK)
 		return retval;
-	LOG_DEBUG("read DCC 0x%08" PRIx32, *data);
 
 	if (dscr_p)
 		*dscr_p = dscr;
@@ -118,7 +134,7 @@ static int dpmv8_read_dcc_64(struct armv8_common *armv8, uint64_t *data,
 		if (retval != ERROR_OK)
 			return retval;
 		if (timeval_ms() > then + 1000) {
-			LOG_ERROR("Timeout waiting for read dcc");
+			LOG_ERROR("Timeout waiting for DTR_TX_FULL, dscr = 0x%08" PRIx32, dscr);
 			return ERROR_FAIL;
 		}
 	}
@@ -136,7 +152,6 @@ static int dpmv8_read_dcc_64(struct armv8_common *armv8, uint64_t *data,
 		return retval;
 
 	*data = *(uint32_t *)data | (uint64_t)higher << 32;
-	LOG_DEBUG("read DCC 0x%16.16" PRIx64, *data);
 
 	if (dscr_p)
 		*dscr_p = dscr;
@@ -150,7 +165,7 @@ static int dpmv8_dpm_prepare(struct arm_dpm *dpm)
 	uint32_t dscr;
 	int retval;
 
-	/* set up invariant:  INSTR_COMP is set after ever DPM operation */
+	/* set up invariant:  ITE is set after ever DPM operation */
 	long long then = timeval_ms();
 	for (;; ) {
 		retval = mem_ap_read_atomic_u32(armv8->debug_ap,
@@ -166,6 +181,9 @@ static int dpmv8_dpm_prepare(struct arm_dpm *dpm)
 		}
 	}
 
+	/* update the stored copy of dscr */
+	dpm->dscr = dscr;
+
 	/* this "should never happen" ... */
 	if (dscr & DSCR_DTR_RX_FULL) {
 		LOG_ERROR("DSCR_DTR_RX_FULL, dscr 0x%08" PRIx32, dscr);
@@ -174,12 +192,6 @@ static int dpmv8_dpm_prepare(struct arm_dpm *dpm)
 			armv8->debug_base + CPUV8_DBG_DTRRX, &dscr);
 		if (retval != ERROR_OK)
 			return retval;
-
-		/* Clear sticky error */
-		retval = mem_ap_write_u32(armv8->debug_ap,
-			armv8->debug_base + CPUV8_DBG_DRCR, DRCR_CSE);
-		if (retval != ERROR_OK)
-			return retval;
 	}
 
 	return retval;
@@ -195,11 +207,9 @@ static int dpmv8_exec_opcode(struct arm_dpm *dpm,
 	uint32_t opcode, uint32_t *p_dscr)
 {
 	struct armv8_common *armv8 = dpm->arm->arch_info;
-	uint32_t dscr = DSCR_ITE;
+	uint32_t dscr = dpm->dscr;
 	int retval;
 
-	LOG_DEBUG("exec opcode 0x%08" PRIx32, opcode);
-
 	if (p_dscr)
 		dscr = *p_dscr;
 
@@ -218,6 +228,9 @@ static int dpmv8_exec_opcode(struct arm_dpm *dpm,
 		}
 	}
 
+	if (armv8_dpm_get_core_state(dpm) != ARM_STATE_AARCH64)
+		opcode = T32_FMTITR(opcode);
+
 	retval = mem_ap_write_u32(armv8->debug_ap,
 			armv8->debug_base + CPUV8_DBG_ITR, opcode);
 	if (retval != ERROR_OK)
@@ -237,6 +250,18 @@ static int dpmv8_exec_opcode(struct arm_dpm *dpm,
 		}
 	} while ((dscr & DSCR_ITE) == 0);	/* Wait for InstrCompl bit to be set */
 
+	/* update dscr and el after each command execution */
+	dpm->dscr = dscr;
+	if (dpm->last_el != ((dscr >> 8) & 3))
+		LOG_DEBUG("EL %i -> %i", dpm->last_el, (dscr >> 8) & 3);
+	dpm->last_el = (dscr >> 8) & 3;
+
+	if (dscr & DSCR_ERR) {
+		LOG_ERROR("Opcode 0x%08"PRIx32", DSCR.ERR=1, DSCR.EL=%i", opcode, dpm->last_el);
+		armv8_dpm_handle_exception(dpm, true);
+		retval = ERROR_FAIL;
+	}
+
 	if (p_dscr)
 		*p_dscr = dscr;
 
@@ -297,96 +322,107 @@ static int dpmv8_instr_write_data_r0_64(struct arm_dpm *dpm,
 	uint32_t opcode, uint64_t data)
 {
 	struct armv8_common *armv8 = dpm->arm->arch_info;
-	uint32_t dscr = DSCR_ITE;
 	int retval;
 
-	retval = dpmv8_write_dcc_64(armv8, data);
-	if (retval != ERROR_OK)
-		return retval;
+	if (dpm->arm->core_state != ARM_STATE_AARCH64)
+		return dpmv8_instr_write_data_r0(dpm, opcode, data);
 
-	retval = dpmv8_exec_opcode(dpm, ARMV8_MRS(SYSTEM_DBG_DBGDTR_EL0, 0), &dscr);
-	if (retval != ERROR_OK)
-		return retval;
+	/* transfer data from DCC to R0 */
+	retval = dpmv8_write_dcc_64(armv8, data);
+	if (retval == ERROR_OK)
+		retval = dpmv8_exec_opcode(dpm, ARMV8_MRS(SYSTEM_DBG_DBGDTR_EL0, 0), &dpm->dscr);
 
 	/* then the opcode, taking data from R0 */
-	return dpmv8_exec_opcode(dpm, opcode, &dscr);
+	if (retval == ERROR_OK)
+		retval = dpmv8_exec_opcode(dpm, opcode, &dpm->dscr);
+
+	return retval;
 }
 
 static int dpmv8_instr_cpsr_sync(struct arm_dpm *dpm)
 {
+	int retval;
 	struct armv8_common *armv8 = dpm->arm->arch_info;
+
 	/* "Prefetch flush" after modifying execution status in CPSR */
-	return dpmv8_exec_opcode(dpm, armv8_opcode(armv8, ARMV8_OPC_DSB_SY), NULL);
+	retval = dpmv8_exec_opcode(dpm, armv8_opcode(armv8, ARMV8_OPC_DSB_SY), &dpm->dscr);
+	if (retval == ERROR_OK)
+		dpmv8_exec_opcode(dpm, armv8_opcode(armv8, ARMV8_OPC_ISB_SY), &dpm->dscr);
+	return retval;
 }
 
 static int dpmv8_instr_read_data_dcc(struct arm_dpm *dpm,
 	uint32_t opcode, uint32_t *data)
 {
 	struct armv8_common *armv8 = dpm->arm->arch_info;
-	uint32_t dscr = DSCR_ITE;
 	int retval;
 
 	/* the opcode, writing data to DCC */
-	retval = dpmv8_exec_opcode(dpm, opcode, &dscr);
+	retval = dpmv8_exec_opcode(dpm, opcode, &dpm->dscr);
 	if (retval != ERROR_OK)
 		return retval;
 
-	return dpmv8_read_dcc(armv8, data, &dscr);
+	return dpmv8_read_dcc(armv8, data, &dpm->dscr);
 }
 
 static int dpmv8_instr_read_data_dcc_64(struct arm_dpm *dpm,
 	uint32_t opcode, uint64_t *data)
 {
 	struct armv8_common *armv8 = dpm->arm->arch_info;
-	uint32_t dscr = DSCR_ITE;
 	int retval;
 
 	/* the opcode, writing data to DCC */
-	retval = dpmv8_exec_opcode(dpm, opcode, &dscr);
+	retval = dpmv8_exec_opcode(dpm, opcode, &dpm->dscr);
 	if (retval != ERROR_OK)
 		return retval;
 
-	return dpmv8_read_dcc_64(armv8, data, &dscr);
+	return dpmv8_read_dcc_64(armv8, data, &dpm->dscr);
 }
 
 static int dpmv8_instr_read_data_r0(struct arm_dpm *dpm,
 	uint32_t opcode, uint32_t *data)
 {
 	struct armv8_common *armv8 = dpm->arm->arch_info;
-	uint32_t dscr = DSCR_ITE;
 	int retval;
 
 	/* the opcode, writing data to R0 */
-	retval = dpmv8_exec_opcode(dpm, opcode, &dscr);
+	retval = dpmv8_exec_opcode(dpm, opcode, &dpm->dscr);
 	if (retval != ERROR_OK)
 		return retval;
 
 	/* write R0 to DCC */
-	retval = dpmv8_exec_opcode(dpm, armv8_opcode(armv8, WRITE_REG_DTRTX), &dscr);
+	retval = dpmv8_exec_opcode(dpm, armv8_opcode(armv8, WRITE_REG_DTRTX), &dpm->dscr);
 	if (retval != ERROR_OK)
 		return retval;
 
-	return dpmv8_read_dcc(armv8, data, &dscr);
+	return dpmv8_read_dcc(armv8, data, &dpm->dscr);
 }
 
 static int dpmv8_instr_read_data_r0_64(struct arm_dpm *dpm,
 	uint32_t opcode, uint64_t *data)
 {
 	struct armv8_common *armv8 = dpm->arm->arch_info;
-	uint32_t dscr = DSCR_ITE;
 	int retval;
 
+	if (dpm->arm->core_state != ARM_STATE_AARCH64) {
+		uint32_t tmp;
+		retval = dpmv8_instr_read_data_r0(dpm, opcode, &tmp);
+		if (retval == ERROR_OK)
+			*data = tmp;
+		return retval;
+	}
+
 	/* the opcode, writing data to R0 */
-	retval = dpmv8_exec_opcode(dpm, opcode, &dscr);
+	retval = dpmv8_exec_opcode(dpm, opcode, &dpm->dscr);
 	if (retval != ERROR_OK)
 		return retval;
 
 	/* write R0 to DCC */
-	retval = dpmv8_exec_opcode(dpm, ARMV8_MSR_GP(SYSTEM_DBG_DBGDTR_EL0, 0), &dscr);
+	retval = dpmv8_exec_opcode(dpm, ARMV8_MSR_GP(SYSTEM_DBG_DBGDTR_EL0, 0), &dpm->dscr);
 	if (retval != ERROR_OK)
 		return retval;
 
-	return dpmv8_read_dcc_64(armv8, data, &dscr);
+	return dpmv8_read_dcc_64(armv8, data, &dpm->dscr);
 }
 
 #if 0
@@ -471,7 +507,7 @@ static int dpmv8_mrc(struct target *target, int cpnum,
 
 	/* read coprocessor register into R0; return via DCC */
 	retval = dpm->instr_read_data_r0(dpm,
-			T32_FMTITR(ARMV4_5_MRC(cpnum, op1, 0, CRn, CRm, op2)),
+			ARMV4_5_MRC(cpnum, op1, 0, CRn, CRm, op2),
 			value);
 
 	/* (void) */ dpm->finish(dpm);
@@ -496,63 +532,7 @@ static int dpmv8_mcr(struct target *target, int cpnum,
 
 	/* read DCC into r0; then write coprocessor register from R0 */
 	retval = dpm->instr_write_data_r0(dpm,
-			T32_FMTITR(ARMV4_5_MCR(cpnum, op1, 0, CRn, CRm, op2)),
-			value);
-
-	/* (void) */ dpm->finish(dpm);
-	return retval;
-}
-
-static int dpmv8_mrs(struct target *target, uint32_t op0,
-	uint32_t op1, uint32_t op2, uint32_t CRn, uint32_t CRm,
-	uint32_t *value)
-{
-	struct arm *arm = target_to_arm(target);
-	struct arm_dpm *dpm = arm->dpm;
-	int retval;
-	uint32_t op_code;
-
-	retval = dpm->prepare(dpm);
-	if (retval != ERROR_OK)
-		return retval;
-	op_code = ((op0 & 0x3) << 19 | (op1 & 0x7) << 16 | (CRn & 0xF) << 12 |\
-				(CRm & 0xF) << 8 | (op2 & 0x7) << 5);
-	op_code >>= 5;
-	LOG_DEBUG("MRS p%d, %d, r0, c%d, c%d, %d", (int)op0,
-		(int) op1, (int) CRn,
-		(int) CRm, (int) op2);
-	/* read coprocessor register into R0; return via DCC */
-	retval = dpm->instr_read_data_r0(dpm,
-			ARMV8_MRS(op_code, 0),
-			value);
-
-	/* (void) */ dpm->finish(dpm);
-	return retval;
-}
-
-static int dpmv8_msr(struct target *target, uint32_t op0,
-	uint32_t op1, uint32_t op2, uint32_t CRn, uint32_t CRm,
-	uint32_t value)
-{
-	struct arm *arm = target_to_arm(target);
-	struct arm_dpm *dpm = arm->dpm;
-	int retval;
-	uint32_t op_code;
-
-	retval = dpm->prepare(dpm);
-	if (retval != ERROR_OK)
-		return retval;
-
-	op_code = ((op0 & 0x3) << 19 | (op1 & 0x7) << 16 | (CRn & 0xF) << 12 |\
-				(CRm & 0xF) << 8 | (op2 & 0x7) << 5);
-	op_code >>= 5;
-	LOG_DEBUG("MSR p%d, %d, r0, c%d, c%d, %d", (int)op0,
-		(int) op1, (int) CRn,
-		(int) CRm, (int) op2);
-
-	/* read DCC into r0; then write coprocessor register from R0 */
-	retval = dpm->instr_write_data_r0(dpm,
-			ARMV8_MSR_GP(op_code, 0),
+			ARMV4_5_MCR(cpnum, op1, 0, CRn, CRm, op2),
 			value);
 
 	/* (void) */ dpm->finish(dpm);
@@ -565,261 +545,182 @@ static int dpmv8_msr(struct target *target, uint32_t op0,
  * Register access utilities
  */
 
-/* Toggles between recorded core mode (USR, SVC, etc) and a temporary one.
- * Routines *must* restore the original mode before returning!!
- */
-int dpmv8_modeswitch(struct arm_dpm *dpm, enum arm_mode mode)
+int armv8_dpm_modeswitch(struct arm_dpm *dpm, enum arm_mode mode)
 {
 	struct armv8_common *armv8 = (struct armv8_common *)dpm->arm->arch_info;
-	int retval;
+	int retval = ERROR_OK;
+	unsigned int target_el;
+	enum arm_state core_state;
 	uint32_t cpsr;
 
 	/* restore previous mode */
-	if (mode == ARM_MODE_ANY)
+	if (mode == ARM_MODE_ANY) {
 		cpsr = buf_get_u32(dpm->arm->cpsr->value, 0, 32);
 
-	/* else force to the specified mode */
-	else
-		cpsr = mode >> 4;
+		LOG_DEBUG("restoring mode, cpsr = 0x%08"PRIx32, cpsr);
 
-	switch ((cpsr & 0xC) >> 2) {
-			case SYSTEM_CUREL_EL1:
-				retval = dpm->instr_execute(dpm, ARMV8_DCPS1(11));
-				if (retval != ERROR_OK)
-					return retval;
-				break;
-			case SYSTEM_CUREL_EL2:
-				retval = dpm->instr_execute(dpm, ARMV8_DCPS2(11));
-				if (retval != ERROR_OK)
-					return retval;
-				break;
-			break;
-			case SYSTEM_CUREL_EL3:
-				retval = dpm->instr_execute(dpm, ARMV8_DCPS3(11));
-				if (retval != ERROR_OK)
-					return retval;
-				break;
-			break;
-			default:
-				LOG_DEBUG("unknow mode 0x%x", (unsigned) ((cpsr & 0xC) >> 2));
-				break;
+	} else {
+		LOG_DEBUG("setting mode 0x%"PRIx32, mode);
+		cpsr = mode;
 	}
 
-
-	retval = dpm->instr_write_data_r0(dpm, armv8_opcode(armv8, WRITE_REG_DSPSR), cpsr);
-	if (retval != ERROR_OK)
-		return retval;
-
-	if (dpm->instr_cpsr_sync)
-		retval = dpm->instr_cpsr_sync(dpm);
-
-	return retval;
-}
-
-static int dpmv8_read_reg32(struct arm_dpm *dpm, struct reg *r, unsigned regnum)
-{
-	uint32_t value;
-	int retval = ERROR_FAIL;
-	bool valid = true;
-
-	switch (regnum) {
-	case 0 ... 14:
-		/* return via DCC:  "MCR p14, 0, Rnum, c0, c5, 0" */
-		retval = dpm->instr_read_data_dcc(dpm,
-			T32_FMTITR(ARMV4_5_MCR(14, 0, regnum, 0, 5, 0)),
-			&value);
+	switch (cpsr & 0x1f) {
+	/* aarch32 modes */
+	case ARM_MODE_USR:
+		target_el = 0;
 		break;
-		case ARMV8_R31:
-			retval = dpm->instr_read_data_dcc(dpm,
-				T32_FMTITR(ARMV4_5_MCR(14, 0, 13, 0, 5, 0)),
-				&value);
-				break;
-		case ARMV8_PC:
-			retval = dpm->instr_read_data_r0(dpm,
-				T32_FMTITR(ARMV8_MRC_DLR(0)),
-				&value);
-			break;
-		case ARMV8_xPSR:
-			retval = dpm->instr_read_data_r0(dpm,
-				T32_FMTITR(ARMV8_MRC_DSPSR(0)),
-				&value);
-			break;
-		default:
-			LOG_DEBUG("READ: %s ignored", r->name);
-			retval = ERROR_OK;
-			value = 0xFFFFFFFF;
-			valid = false;
-			break;
+	case ARM_MODE_SVC:
+	case ARM_MODE_ABT:
+	case ARM_MODE_IRQ:
+	case ARM_MODE_FIQ:
+	case ARM_MODE_SYS:
+		target_el = 1;
+		break;
+	/*
+	 * TODO: handle ARM_MODE_HYP
+	 * case ARM_MODE_HYP:
+	 *      target_el = 2;
+	 *      break;
+	 */
+	case ARM_MODE_MON:
+		target_el = 3;
+		break;
+	/* aarch64 modes */
+	default:
+		target_el = (cpsr >> 2) & 3;
 	}
 
-	if (retval == ERROR_OK) {
-		r->valid = valid;
-		r->dirty = false;
-		buf_set_u64(r->value, 0, 32, value);
-		LOG_DEBUG("READ: %s, %8.8x", r->name, (unsigned) value);
+	if (target_el > SYSTEM_CUREL_EL3) {
+		LOG_ERROR("%s: Invalid target exception level %i", __func__, target_el);
+		return ERROR_FAIL;
 	}
-	return retval;
-}
 
-static int dpmv8_write_reg32(struct arm_dpm *dpm, struct reg *r, unsigned regnum)
-{
-	int retval;
-	uint64_t value = buf_get_u64(r->value, 0, 32);
+	LOG_DEBUG("target_el = %i, last_el = %i", target_el, dpm->last_el);
+	if (target_el > dpm->last_el) {
+		retval = dpm->instr_execute(dpm,
+				armv8_opcode(armv8, ARMV8_OPC_DCPS) | target_el);
 
-	switch (regnum) {
-		case 0 ... 14:
-			/* load register from DCC:  "MRC p14, 0, Rnum, c0, c5, 0" */
-			retval = dpm->instr_write_data_dcc(dpm,
-					T32_FMTITR(ARMV4_5_MRC(14, 0, regnum, 0, 5, 0)), value);
-			break;
-		case ARMV8_PC:/* PC
-			 * read r0 from DCC; then "MOV pc, r0" */
-			retval = dpm->instr_write_data_r0(dpm,
-					T32_FMTITR(ARMV8_MCR_DLR(0)), value);
-			break;
-		case ARMV8_xPSR: /* CPSR */
-			/* read r0 from DCC, then "MCR r0, DSPSR" */
-			retval = dpm->instr_write_data_r0(dpm,
-					T32_FMTITR(ARMV8_MCR_DSPSR(0)), value);
-			break;
-		default:
-			retval = ERROR_OK;
-			LOG_DEBUG("WRITE: %s ignored", r->name);
-			break;
-	}
+		/* DCPS clobbers registers just like an exception taken */
+		armv8_dpm_handle_exception(dpm, false);
+	} else {
+		core_state = armv8_dpm_get_core_state(dpm);
+		if (core_state != ARM_STATE_AARCH64) {
+			/* cannot do DRPS/ERET when already in EL0 */
+			if (dpm->last_el != 0) {
+				/* load SPSR with the desired mode and execute DRPS */
+				LOG_DEBUG("SPSR = 0x%08"PRIx32, cpsr);
+				retval = dpm->instr_write_data_r0(dpm,
+						ARMV8_MSR_GP_xPSR_T1(1, 0, 15), cpsr);
+				if (retval == ERROR_OK)
+					retval = dpm->instr_execute(dpm, armv8_opcode(armv8, ARMV8_OPC_DRPS));
+			}
+		} else {
+			/*
+			 * need to execute multiple DRPS instructions until target_el
+			 * is reached
+			 */
+			while (retval == ERROR_OK && dpm->last_el != target_el) {
+				unsigned int cur_el = dpm->last_el;
+				retval = dpm->instr_execute(dpm, armv8_opcode(armv8, ARMV8_OPC_DRPS));
+				if (cur_el == dpm->last_el) {
+					LOG_INFO("Cannot reach EL %i, SPSR corrupted?", target_el);
+					break;
+				}
+			}
+		}
 
-	if (retval == ERROR_OK) {
-		r->dirty = false;
-		LOG_DEBUG("WRITE: %s, %8.8x", r->name, (unsigned) value);
+		/* On executing DRPS, DSPSR and DLR become UNKNOWN, mark them as dirty */
+		dpm->arm->cpsr->dirty = true;
+		dpm->arm->pc->dirty = true;
+
+		/*
+		 * re-evaluate the core state, we might be in Aarch32 state now
+		 * we rely on dpm->dscr being up-to-date
+		 */
+		core_state = armv8_dpm_get_core_state(dpm);
+		armv8_select_opcodes(armv8, core_state == ARM_STATE_AARCH64);
+		armv8_select_reg_access(armv8, core_state == ARM_STATE_AARCH64);
 	}
 
 	return retval;
 }
 
-/* just read the register -- rely on the core mode being right */
+/*
+ * Common register read, relies on armv8_select_reg_access() having been called.
+ */
 static int dpmv8_read_reg(struct arm_dpm *dpm, struct reg *r, unsigned regnum)
 {
-	uint32_t value;
-	uint64_t value_64;
+	struct armv8_common *armv8 = dpm->arm->arch_info;
 	int retval = ERROR_FAIL;
 
-	switch (regnum) {
-		case 0 ... 30:
-			retval = dpm->instr_read_data_dcc_64(dpm,
-				ARMV8_MSR_GP(SYSTEM_DBG_DBGDTR_EL0, regnum),
-				&value_64);
-			break;
-		case ARMV8_R31:
-			retval = dpm->instr_read_data_r0_64(dpm,
-				ARMV8_MOVFSP_64(0),
-				&value_64);
-			break;
-		case ARMV8_PC:
-			retval = dpm->instr_read_data_r0_64(dpm,
-				ARMV8_MRS_DLR(0),
-				&value_64);
-			break;
-		case ARMV8_xPSR:
-			retval = dpm->instr_read_data_r0(dpm,
-				ARMV8_MRS_DSPSR(0),
-				&value);
-			break;
-		default:
-			LOG_DEBUG("READ: %s fail", r->name);
-			break;
-	}
-
-	if (retval == ERROR_OK) {
-		r->valid = true;
-		r->dirty = false;
-		if (r->size == 64) {
-			buf_set_u64(r->value, 0, 64, value_64);
-			LOG_DEBUG("READ: %s, %16.8llx", r->name, (unsigned long long) value_64);
-		} else {
-			buf_set_u32(r->value, 0, 32, value);
-			LOG_DEBUG("READ: %s, %8.8x", r->name, (unsigned) value);
+	if (r->size <= 64) {
+		uint64_t value_64;
+		retval = armv8->read_reg_u64(armv8, regnum, &value_64);
+
+		if (retval == ERROR_OK) {
+			r->valid = true;
+			r->dirty = false;
+			buf_set_u64(r->value, 0, r->size, value_64);
+			if (r->size == 64)
+				LOG_DEBUG("READ: %s, %16.8llx", r->name, (unsigned long long) value_64);
+			else
+				LOG_DEBUG("READ: %s, %8.8x", r->name, (unsigned int) value_64);
 		}
-	}
-	return retval;
-}
+	} else if (r->size <= 128) {
+		uint64_t lvalue = 0, hvalue = 0;
+		retval = armv8->read_reg_u128(armv8, regnum, &lvalue, &hvalue);
 
-/* just write the register -- rely on the core mode being right */
-static int dpmv8_write_reg(struct arm_dpm *dpm, struct reg *r, unsigned regnum)
-{
-	int retval = ERROR_FAIL;
-	uint32_t value = 0xFFFFFFFF;
-	uint64_t value_64 = 0xFFFFFFFFFFFFFFFF;
-
-	switch (regnum) {
-		case 0 ... 30:
-			value_64 = buf_get_u64(r->value, 0, 64);
-			retval = dpm->instr_write_data_dcc_64(dpm,
-				ARMV8_MRS(SYSTEM_DBG_DBGDTR_EL0, regnum),
-				value_64);
-			break;
-		case ARMV8_R31:
-			value_64 = buf_get_u64(r->value, 0, 64);
-			retval = dpm->instr_write_data_r0_64(dpm,
-				ARMV8_MOVTSP_64(0),
-				value_64);
-			break;
-		case ARMV8_PC:
-			value_64 = buf_get_u64(r->value, 0, 64);
-			retval = dpm->instr_write_data_r0_64(dpm,
-				ARMV8_MSR_DLR(0),
-				value_64);
-			break;
-		case ARMV8_xPSR:
-			value = buf_get_u32(r->value, 0, 32);
-			retval = dpm->instr_write_data_r0(dpm,
-				ARMV8_MSR_DSPSR(0),
-				value);
-			break;
-		default:
-			LOG_DEBUG("write: %s fail", r->name);
-			break;
-	}
+		if (retval == ERROR_OK) {
+			r->valid = true;
+			r->dirty = false;
 
+			buf_set_u64(r->value, 0, 64, lvalue);
+			buf_set_u64(r->value + 8, 0, r->size - 64, hvalue);
 
-	if (retval == ERROR_OK) {
-		r->dirty = false;
-		if (r->size == 64)
-			LOG_DEBUG("WRITE: %s, %16.8llx", r->name, (unsigned long long) value_64);
-		else
-			LOG_DEBUG("WRITE: %s, %8.8x", r->name, (unsigned) value);
+			LOG_DEBUG("READ: %s, lvalue=%16.8llx", r->name, (unsigned long long) lvalue);
+			LOG_DEBUG("READ: %s, hvalue=%16.8llx", r->name, (unsigned long long) hvalue);
+		}
 	}
-
 	return retval;
 }
 
-static inline enum arm_state dpm_get_core_state(uint32_t dscr)
+/*
+ * Common register write, relies on armv8_select_reg_access() having been called.
+ */
+static int dpmv8_write_reg(struct arm_dpm *dpm, struct reg *r, unsigned regnum)
 {
-	int el = (dscr >> 8) & 0x3;
-	int rw = (dscr >> 10) & 0xF;
+	struct armv8_common *armv8 = dpm->arm->arch_info;
+	int retval = ERROR_FAIL;
 
-	LOG_DEBUG("EL:%i, RW:0x%x", el, rw);
+	if (r->size <= 64) {
+		uint64_t value_64;
 
-	/* DSCR.RW = 0b1111 - all EL are using AArch64 state */
-	if (rw == 0xF)
-		return ARM_STATE_AARCH64;
+		value_64 = buf_get_u64(r->value, 0, r->size);
+		retval = armv8->write_reg_u64(armv8, regnum, value_64);
 
-	/* DSCR.RW = 0b1110 - all EL > 0 are using AArch64 state */
-	if (rw == 0xE && el > 0)
-		return ARM_STATE_AARCH64;
+		if (retval == ERROR_OK) {
+			r->dirty = false;
+			if (r->size == 64)
+				LOG_DEBUG("WRITE: %s, %16.8llx", r->name, (unsigned long long)value_64);
+			else
+				LOG_DEBUG("WRITE: %s, %8.8x", r->name, (unsigned int)value_64);
+		}
+	} else if (r->size <= 128) {
+		uint64_t lvalue, hvalue;
 
-	/* DSCR.RW = 0b110x - all EL > 1 are using Aarch64 state */
-	if ((rw & 0xE) == 0xC && el > 1)
-		return ARM_STATE_AARCH64;
+		lvalue = buf_get_u64(r->value, 0, 64);
+		hvalue = buf_get_u64(r->value + 8, 0, r->size - 64);
+		retval = armv8->write_reg_u128(armv8, regnum, lvalue, hvalue);
 
-	/* DSCR.RW = 0b10xx - all EL > 2 are using Aarch64 state */
-	if ((rw & 0xC) == 0x8 && el > 2)
-		return ARM_STATE_AARCH64;
+		if (retval == ERROR_OK) {
+			r->dirty = false;
 
-	/* DSCR.RW = 0b0xxx - all EL are using AArch32 state */
-	if ((rw & 0x8) == 0)
-		return ARM_STATE_ARM;
+			LOG_DEBUG("WRITE: %s, lvalue=%16.8llx", r->name, (unsigned long long) lvalue);
+			LOG_DEBUG("WRITE: %s, hvalue=%16.8llx", r->name, (unsigned long long) hvalue);
+		}
+	}
 
-	return ARM_STATE_ARM;
+	return retval;
 }
 
 /**
@@ -833,60 +734,75 @@ int armv8_dpm_read_current_registers(struct arm_dpm *dpm)
 {
 	struct arm *arm = dpm->arm;
 	struct armv8_common *armv8 = (struct armv8_common *)arm->arch_info;
-	enum arm_state core_state;
+	struct reg_cache *cache;
+	struct reg *r;
 	uint32_t cpsr;
-
 	int retval;
-	struct reg *r;
 
 	retval = dpm->prepare(dpm);
 	if (retval != ERROR_OK)
 		return retval;
 
-	core_state = dpm_get_core_state(dpm->dscr);
-
-	armv8_select_opcodes(armv8, core_state);
+	cache = arm->core_cache;
 
 	/* read R0 first (it's used for scratch), then CPSR */
-	r = arm->core_cache->reg_list + 0;
+	r = cache->reg_list + ARMV8_R0;
 	if (!r->valid) {
-		retval = core_state == ARM_STATE_AARCH64 ?
-					dpmv8_read_reg(dpm, r, 0) : dpmv8_read_reg32(dpm, r, 0);
+		retval = dpmv8_read_reg(dpm, r, ARMV8_R0);
 		if (retval != ERROR_OK)
 			goto fail;
 	}
 	r->dirty = true;
 
+	/* read R1, too, it will be clobbered during memory access */
+	r = cache->reg_list + ARMV8_R1;
+	if (!r->valid) {
+		retval = dpmv8_read_reg(dpm, r, ARMV8_R1);
+		if (retval != ERROR_OK)
+			goto fail;
+	}
+
 	/* read cpsr to r0 and get it back */
-	retval = dpm->instr_read_data_r0(dpm, armv8_opcode(armv8, READ_REG_DSPSR), &cpsr);
+	retval = dpm->instr_read_data_r0(dpm,
+			armv8_opcode(armv8, READ_REG_DSPSR), &cpsr);
 	if (retval != ERROR_OK)
 		goto fail;
 
-	/* update core mode and state, plus shadow mapping for R8..R14 */
+	/* update core mode and state */
 	armv8_set_cpsr(arm, cpsr);
 
-	/* REVISIT we can probably avoid reading R1..R14, saving time... */
-	for (unsigned i = 1; i < arm->core_cache->num_regs ; i++) {
+	for (unsigned int i = ARMV8_PC; i < cache->num_regs ; i++) {
+		struct arm_reg *arm_reg;
+
 		r = armv8_reg_current(arm, i);
 		if (r->valid)
 			continue;
 
-		retval = core_state == ARM_STATE_AARCH64 ?
-					dpmv8_read_reg(dpm, r, i) : dpmv8_read_reg32(dpm, r, i);
+		/* Skip reading FP-SIMD registers */
+		if (r->number >= ARMV8_V0 && r->number <= ARMV8_FPCR)
+			continue;
+
+		/*
+		 * Only read registers that are available from the
+		 * current EL (or core mode).
+		 */
+		arm_reg = r->arch_info;
+		if (arm_reg->mode != ARM_MODE_ANY &&
+				dpm->last_el != armv8_curel_from_core_mode(arm_reg->mode))
+			continue;
+
+		/* Special case: ARM_MODE_SYS has no SPSR at EL1 */
+		if (r->number == ARMV8_SPSR_EL1 && arm->core_mode == ARM_MODE_SYS)
+			continue;
 
+		retval = dpmv8_read_reg(dpm, r, i);
 		if (retval != ERROR_OK)
 			goto fail;
-	}
-
-	/* NOTE: SPSR ignored (if it's even relevant). */
 
-	/* REVISIT the debugger can trigger various exceptions.  See the
-	 * ARMv7A architecture spec, section C5.7, for more info about
-	 * what defenses are needed; v6 debug has the most issues.
-	 */
+	}
 
 fail:
-	/* (void) */ dpm->finish(dpm);
+	dpm->finish(dpm);
 	return retval;
 }
 
@@ -951,7 +867,6 @@ int armv8_dpm_write_dirty_registers(struct arm_dpm *dpm, bool bpwp)
 	struct arm *arm = dpm->arm;
 	struct reg_cache *cache = arm->core_cache;
 	int retval;
-	bool is_aarch64 = arm->core_state == ARM_STATE_AARCH64;
 
 	retval = dpm->prepare(dpm);
 	if (retval != ERROR_OK)
@@ -991,59 +906,48 @@ int armv8_dpm_write_dirty_registers(struct arm_dpm *dpm, bool bpwp)
 	 * be queued, and need (efficient/batched) flushing later.
 	 */
 
-	/* Scan the registers until we find one that's both dirty and
-	 * eligible for flushing.  Flush that and everything else that
-	 * shares the same core mode setting.  Typically this won't
-	 * actually find anything to do...
-	 */
+	/* Restore original core mode and state */
+	retval = armv8_dpm_modeswitch(dpm, ARM_MODE_ANY);
+	if (retval != ERROR_OK)
+		goto done;
 
 	/* check everything except our scratch register R0 */
 	for (unsigned i = 1; i < cache->num_regs; i++) {
 		struct arm_reg *r;
-		unsigned regnum;
 
-		/* also skip PC, CPSR, and non-dirty */
-		if (i == (arm->core_cache->num_regs - 2))
+		/* skip PC and CPSR */
+		if (i == ARMV8_PC || i == ARMV8_xPSR)
 			continue;
-		if (arm->cpsr == cache->reg_list + i)
+		/* skip invalid */
+		if (!cache->reg_list[i].valid)
 			continue;
+		/* skip non-dirty */
 		if (!cache->reg_list[i].dirty)
 			continue;
 
+		/* skip all registers not on the current EL */
 		r = cache->reg_list[i].arch_info;
-		regnum = r->num;
+		if (r->mode != ARM_MODE_ANY &&
+				dpm->last_el != armv8_curel_from_core_mode(r->mode))
+			continue;
 
-		retval = is_aarch64 ? dpmv8_write_reg(dpm, &cache->reg_list[i], regnum)
-				: dpmv8_write_reg32(dpm, &cache->reg_list[i], regnum);
+		retval = dpmv8_write_reg(dpm, &cache->reg_list[i], i);
 		if (retval != ERROR_OK)
-			goto done;
+			break;
 	}
 
-
-	/* Restore original CPSR ... assuming either that we changed it,
-	 * or it's dirty.  Must write PC to ensure the return address is
-	 * defined, and must not write it before CPSR.
-	 */
-	retval = dpmv8_modeswitch(dpm, ARM_MODE_ANY);
-	if (retval != ERROR_OK)
-		goto done;
-	arm->cpsr->dirty = false;
-
-	retval = is_aarch64 ? dpmv8_write_reg(dpm, arm->pc, (arm->core_cache->num_regs - 2))
-			: dpmv8_write_reg32(dpm, arm->pc, (arm->core_cache->num_regs - 2));
-	if (retval != ERROR_OK)
-		goto done;
-	arm->pc->dirty = false;
-
+	/* flush CPSR and PC */
+	if (retval == ERROR_OK)
+		retval = dpmv8_write_reg(dpm, &cache->reg_list[ARMV8_xPSR], ARMV8_xPSR);
+	if (retval == ERROR_OK)
+		retval = dpmv8_write_reg(dpm, &cache->reg_list[ARMV8_PC], ARMV8_PC);
 	/* flush R0 -- it's *very* dirty by now */
-	retval = is_aarch64 ? dpmv8_write_reg(dpm, &cache->reg_list[0], 0)
-			: dpmv8_write_reg32(dpm, &cache->reg_list[0], 0);
-	if (retval != ERROR_OK)
-		goto done;
-	cache->reg_list[0].dirty = false;
-
-	/* (void) */ dpm->finish(dpm);
+	if (retval == ERROR_OK)
+		retval = dpmv8_write_reg(dpm, &cache->reg_list[0], 0);
+	if (retval == ERROR_OK)
+		dpm->instr_cpsr_sync(dpm);
 done:
+	dpm->finish(dpm);
 	return retval;
 }
 
@@ -1061,19 +965,18 @@ static int armv8_dpm_read_core_reg(struct target *target, struct reg *r,
 	int retval;
 	int max = arm->core_cache->num_regs;
 
-	if (regnum < 0 || regnum > max)
+	if (regnum < 0 || regnum >= max)
 		return ERROR_COMMAND_SYNTAX_ERROR;
 
-	/* REVISIT what happens if we try to read SPSR in a core mode
+	/*
+	 * REVISIT what happens if we try to read SPSR in a core mode
 	 * which has no such register?
 	 */
-
 	retval = dpm->prepare(dpm);
 	if (retval != ERROR_OK)
 		return retval;
 
-	retval = arm->core_state == ARM_STATE_AARCH64 ?
-			dpmv8_read_reg(dpm, r, regnum) : dpmv8_read_reg32(dpm, r, regnum);
+	retval = dpmv8_read_reg(dpm, r, regnum);
 	if (retval != ERROR_OK)
 		goto fail;
 
@@ -1101,12 +1004,11 @@ static int armv8_dpm_write_core_reg(struct target *target, struct reg *r,
 	if (retval != ERROR_OK)
 		return retval;
 
-	retval = arm->core_state == ARM_STATE_AARCH64 ?
-			dpmv8_write_reg(dpm, r, regnum) : dpmv8_write_reg32(dpm, r, regnum);
+	retval = dpmv8_write_reg(dpm, r, regnum);
 
 	/* always clean up, regardless of error */
+	dpm->finish(dpm);
 
-	/* (void) */ dpm->finish(dpm);
 	return retval;
 }
 
@@ -1152,9 +1054,9 @@ static int armv8_dpm_full_context(struct target *target)
 				 * in FIQ mode we need to patch mode.
 				 */
 				if (mode != ARM_MODE_ANY)
-					retval = dpmv8_modeswitch(dpm, mode);
+					retval = armv8_dpm_modeswitch(dpm, mode);
 				else
-					retval = dpmv8_modeswitch(dpm, ARM_MODE_USR);
+					retval = armv8_dpm_modeswitch(dpm, ARM_MODE_USR);
 
 				if (retval != ERROR_OK)
 					goto done;
@@ -1172,7 +1074,7 @@ static int armv8_dpm_full_context(struct target *target)
 
 	} while (did_read);
 
-	retval = dpmv8_modeswitch(dpm, ARM_MODE_ANY);
+	retval = armv8_dpm_modeswitch(dpm, ARM_MODE_ANY);
 	/* (void) */ dpm->finish(dpm);
 done:
 	return retval;
@@ -1385,12 +1287,72 @@ void armv8_dpm_report_wfar(struct arm_dpm *dpm, uint64_t addr)
 			/* ?? */
 			break;
 		default:
-			LOG_DEBUG("Unknow core_state");
+			LOG_DEBUG("Unknown core_state");
 			break;
 	}
 	dpm->wp_pc = addr;
 }
 
+/*
+ * Handle exceptions taken in debug state. This happens mostly for memory
+ * accesses that violated a MMU policy. Taking an exception while in debug
+ * state clobbers certain state registers on the target exception level.
+ * Just mark those registers dirty so that they get restored on resume.
+ * This works both for Aarch32 and Aarch64 states.
+ *
+ * This function must not perform any actions that trigger another exception
+ * or a recursion will happen.
+ */
+void armv8_dpm_handle_exception(struct arm_dpm *dpm, bool do_restore)
+{
+	struct armv8_common *armv8 = dpm->arm->arch_info;
+	struct reg_cache *cache = dpm->arm->core_cache;
+	enum arm_state core_state;
+	uint64_t dlr;
+	uint32_t dspsr;
+	unsigned int el;
+
+	static const int clobbered_regs_by_el[3][5] = {
+		{ ARMV8_PC, ARMV8_xPSR, ARMV8_ELR_EL1, ARMV8_ESR_EL1, ARMV8_SPSR_EL1 },
+		{ ARMV8_PC, ARMV8_xPSR, ARMV8_ELR_EL2, ARMV8_ESR_EL2, ARMV8_SPSR_EL2 },
+		{ ARMV8_PC, ARMV8_xPSR, ARMV8_ELR_EL3, ARMV8_ESR_EL3, ARMV8_SPSR_EL3 },
+	};
+
+	el = (dpm->dscr >> 8) & 3;
+
+	/* safety check, must not happen since EL0 cannot be a target for an exception */
+	if (el < SYSTEM_CUREL_EL1 || el > SYSTEM_CUREL_EL3) {
+		LOG_ERROR("%s: EL %i is invalid, DSCR corrupted?", __func__, el);
+		return;
+	}
+
+	/* Clear sticky error */
+	mem_ap_write_u32(armv8->debug_ap,
+		armv8->debug_base + CPUV8_DBG_DRCR, DRCR_CSE);
+
+	armv8->read_reg_u64(armv8, ARMV8_xPSR, &dlr);
+	dspsr = dlr;
+	armv8->read_reg_u64(armv8, ARMV8_PC, &dlr);
+
+	LOG_DEBUG("Exception taken to EL %i, DLR=0x%016"PRIx64" DSPSR=0x%08"PRIx32,
+			el, dlr, dspsr);
+
+	/* mark all clobbered registers as dirty */
+	for (int i = 0; i < 5; i++)
+		cache->reg_list[clobbered_regs_by_el[el-1][i]].dirty = true;
+
+	/*
+	 * re-evaluate the core state, we might be in Aarch64 state now
+	 * we rely on dpm->dscr being up-to-date
+	 */
+	core_state = armv8_dpm_get_core_state(dpm);
+	armv8_select_opcodes(armv8, core_state == ARM_STATE_AARCH64);
+	armv8_select_reg_access(armv8, core_state == ARM_STATE_AARCH64);
+
+	if (do_restore)
+		armv8_dpm_modeswitch(dpm, ARM_MODE_ANY);
+}
+
 /*----------------------------------------------------------------------*/
 
 /*
@@ -1402,6 +1364,7 @@ void armv8_dpm_report_dscr(struct arm_dpm *dpm, uint32_t dscr)
 	struct target *target = dpm->arm->target;
 
 	dpm->dscr = dscr;
+	dpm->last_el = (dscr >> 8) & 3;
 
 	/* Examine debug reason */
 	switch (DSCR_ENTRY(dscr)) {
@@ -1418,13 +1381,15 @@ void armv8_dpm_report_dscr(struct arm_dpm *dpm, uint32_t dscr)
 		case DSCRV8_ENTRY_BKPT:	/* SW BKPT (?) */
 		case DSCRV8_ENTRY_RESET_CATCH:	/* Reset catch */
 		case DSCRV8_ENTRY_OS_UNLOCK:  /*OS unlock catch*/
-		case DSCRV8_ENTRY_EXCEPTION_CATCH:  /*exception catch*/
 		case DSCRV8_ENTRY_SW_ACCESS_DBG: /*SW access dbg register*/
 			target->debug_reason = DBG_REASON_BREAKPOINT;
 			break;
 		case DSCRV8_ENTRY_WATCHPOINT:	/* asynch watchpoint */
 			target->debug_reason = DBG_REASON_WATCHPOINT;
 			break;
+		case DSCRV8_ENTRY_EXCEPTION_CATCH:  /*exception catch*/
+			target->debug_reason = DBG_REASON_EXC_CATCH;
+			break;
 		default:
 			target->debug_reason = DBG_REASON_UNDEFINED;
 			break;
@@ -1465,8 +1430,6 @@ int armv8_dpm_setup(struct arm_dpm *dpm)
 	/* coprocessor access setup */
 	arm->mrc = dpmv8_mrc;
 	arm->mcr = dpmv8_mcr;
-	arm->mrs = dpmv8_mrs;
-	arm->msr = dpmv8_msr;
 
 	dpm->prepare = dpmv8_dpm_prepare;
 	dpm->finish = dpmv8_dpm_finish;