[OpenOCD-devel] [PATCH]: 9b7c17f gdb_server, rtos: Numerous hwthread improvements

[<ge...@op...>]

This is an automated email from Gerrit.

Tim Newsome (ti...@si...) just uploaded a new patch set to Gerrit, which you can find at http://openocd.zylin.com/5101

-- gerrit

commit 9b7c17f28de1412f8ba6ceedbe689b4ab21395a6
Author: Tim Newsome <ti...@si...>
Date:   Mon Apr 8 16:42:48 2019 -0700

    gdb_server, rtos: Numerous hwthread improvements
    
    1. Change hwthread_update_threads() to preserve current_threadid.
    Arguably hwthread_update_threads() should always be a nop after the
    initial call, since the number of threads is static, configured in the
    startup script.
    2. Add get_thread_reg() to rtos. It's used in rtos_get_gdb_reg() to read
    the value of a single register, instead of reading all register values
    by calling get_thread_reg_list().
    3. Add set_reg() to rtos. gdb_server uses this to change a single
    register value for a specific thread.
    4. Add target_get_gdb_reg_list_noread() so it's possible for gdb to get
    a list of registers without attempting to read their contents.
    
    The clang static checker doesn't find any new problems with this change.
    
    Signed-off-by: Tim Newsome <ti...@si...>
    Change-Id: I7d040790268cd942ae3b66ec2781b0124f1bde8d

diff --git a/src/rtos/hwthread.c b/src/rtos/hwthread.c
index 2d9e42f..4d05d19 100644
--- a/src/rtos/hwthread.c
+++ b/src/rtos/hwthread.c
@@ -31,10 +31,13 @@
 static bool hwthread_detect_rtos(struct target *target);
 static int hwthread_create(struct target *target);
 static int hwthread_update_threads(struct rtos *rtos);
+static int hwthread_get_thread_reg(struct rtos *rtos, int64_t thread_id,
+		uint32_t reg_num, struct rtos_reg *rtos_reg);
 static int hwthread_get_thread_reg_list(struct rtos *rtos, int64_t thread_id,
-					struct rtos_reg **reg_list, int *num_regs);
+		struct rtos_reg **reg_list, int *num_regs);
 static int hwthread_get_symbol_list_to_lookup(symbol_table_elem_t *symbol_list[]);
 static int hwthread_smp_init(struct target *target);
+int hwthread_set_reg(struct rtos *rtos, uint32_t reg_num, uint8_t *reg_value);
 
 #define HW_THREAD_NAME_STR_SIZE (32)
 
@@ -51,8 +54,10 @@ const struct rtos_type hwthread_rtos = {
 	.create = hwthread_create,
 	.update_threads = hwthread_update_threads,
 	.get_thread_reg_list = hwthread_get_thread_reg_list,
+	.get_thread_reg = hwthread_get_thread_reg,
 	.get_symbol_list_to_lookup = hwthread_get_symbol_list_to_lookup,
 	.smp_init = hwthread_smp_init,
+	.set_reg = hwthread_set_reg,
 };
 
 struct hwthread_params {
@@ -87,13 +92,10 @@ static int hwthread_update_threads(struct rtos *rtos)
 	enum target_debug_reason current_reason = DBG_REASON_UNDEFINED;
 
 	if (rtos == NULL)
-		return -1;
+		return ERROR_FAIL;
 
 	target = rtos->target;
 
-	/* wipe out previous thread details if any */
-	rtos_free_threadlist(rtos);
-
 	/* determine the number of "threads" */
 	if (target->smp) {
 		for (head = target->head; head != NULL; head = head->next) {
@@ -104,9 +106,16 @@ static int hwthread_update_threads(struct rtos *rtos)
 
 			++thread_list_size;
 		}
+
+		assert(thread_list_size);
 	} else
 		thread_list_size = 1;
 
+	/* Wipe out previous thread details if any, but preserve threadid. */
+	int64_t current_threadid = rtos->current_threadid;
+	rtos_free_threadlist(rtos);
+	rtos->current_threadid = current_threadid;
+
 	/* create space for new thread details */
 	rtos->thread_details = malloc(sizeof(struct thread_detail) * thread_list_size);
 
@@ -201,64 +210,114 @@ static int hwthread_smp_init(struct target *target)
 	return hwthread_update_threads(target->rtos);
 }
 
-static int hwthread_get_thread_reg_list(struct rtos *rtos, int64_t thread_id,
-					struct rtos_reg **rtos_reg_list, int *num_regs)
+static struct target *find_thread(struct target *target, int64_t thread_id)
 {
-	struct target_list *head;
-	struct target *target;
-	struct target *curr;
-	struct reg **reg_list;
-	int retval;
-
-	if (rtos == NULL)
-		return ERROR_FAIL;
-
-	target = rtos->target;
-
 	/* Find the thread with that thread_id */
+	if (target == NULL)
+		return NULL;
 	if (target->smp) {
-		curr = NULL;
-		for (head = target->head; head != NULL; head = head->next) {
-			curr = head->target;
-
-			if (thread_id == threadid_from_target(curr))
-				break;
+		for (struct target_list *head = target->head; head != NULL; head = head->next) {
+			if (thread_id == threadid_from_target(head->target))
+				return head->target;
 		}
+	} else if (thread_id == threadid_from_target(target)) {
+		return target;
+	}
+	return NULL;
+}
 
-		if (head == NULL)
-			return ERROR_FAIL;
-	} else {
-		curr = target;
-		if (thread_id != threadid_from_target(curr))
-			return ERROR_FAIL;
+static int hwthread_get_thread_reg_list(struct rtos *rtos, int64_t thread_id,
+		struct rtos_reg **rtos_reg_list, int *rtos_reg_list_size)
+{
+	if (rtos == NULL)
+		return ERROR_FAIL;
 
-	}
+	struct target *target = rtos->target;
+
+	struct target *curr = find_thread(target, thread_id);
+	if (curr == NULL)
+		return ERROR_FAIL;
 
 	if (!target_was_examined(curr))
 		return ERROR_FAIL;
 
-	retval = target_get_gdb_reg_list(curr, &reg_list, num_regs,
+	struct reg **reg_list;
+	int retval = target_get_gdb_reg_list(curr, &reg_list, rtos_reg_list_size,
 			REG_CLASS_GENERAL);
 	if (retval != ERROR_OK)
 		return retval;
 
-	*rtos_reg_list = calloc(*num_regs, sizeof(struct rtos_reg));
+	*rtos_reg_list = calloc(*rtos_reg_list_size, sizeof(struct rtos_reg));
 	if (*rtos_reg_list == NULL) {
 		free(reg_list);
 		return ERROR_FAIL;
 	}
 
-	for (int i = 0; i < *num_regs; i++) {
+	for (int i = 0; i < *rtos_reg_list_size; i++) {
 		(*rtos_reg_list)[i].number = (*reg_list)[i].number;
 		(*rtos_reg_list)[i].size = (*reg_list)[i].size;
 		memcpy((*rtos_reg_list)[i].value, (*reg_list)[i].value,
-		       ((*reg_list)[i].size + 7) / 8);
+				((*reg_list)[i].size + 7) / 8);
 	}
-
 	free(reg_list);
 
 	return ERROR_OK;
+}
+
+static int hwthread_get_thread_reg(struct rtos *rtos, int64_t thread_id,
+		uint32_t reg_num, struct rtos_reg *rtos_reg)
+{
+	if (rtos == NULL)
+		return ERROR_FAIL;
 
+	struct target *target = rtos->target;
+
+	struct target *curr = find_thread(target, thread_id);
+	if (curr == NULL) {
+		LOG_ERROR("Couldn't find RTOS thread for id %" PRId64 ".", thread_id);
+		return ERROR_FAIL;
+	}
+
+	if (!target_was_examined(curr)) {
+		LOG_ERROR("Target %d hasn't been examined yet.", curr->coreid);
+		return ERROR_FAIL;
+	}
+
+	struct reg *reg = register_get_by_number(curr->reg_cache, reg_num, true);
+	if (!reg) {
+		LOG_ERROR("Couldn't find register %d in thread %" PRId64 ".", reg_num,
+				thread_id);
+		return ERROR_FAIL;
+	}
+
+	if (reg->type->get(reg) != ERROR_OK)
+		return ERROR_FAIL;
+
+	rtos_reg->number = reg->number;
+	rtos_reg->size = reg->size;
+	unsigned bytes = (reg->size + 7) / 8;
+	assert(bytes <= sizeof(rtos_reg->value));
+	memcpy(rtos_reg->value, reg->value, bytes);
+
+	return ERROR_OK;
+}
+
+int hwthread_set_reg(struct rtos *rtos, uint32_t reg_num, uint8_t *reg_value)
+{
+	if (rtos == NULL)
+		return ERROR_FAIL;
+
+	struct target *target = rtos->target;
+
+	struct target *curr = find_thread(target, rtos->current_thread);
+	if (curr == NULL)
+		return ERROR_FAIL;
+
+	struct reg *reg = register_get_by_number(curr->reg_cache, reg_num, true);
+	if (!reg)
+		return ERROR_FAIL;
+
+	return reg->type->set(reg, reg_value);
 }
 
 static int hwthread_get_symbol_list_to_lookup(symbol_table_elem_t *symbol_list[])
@@ -272,26 +331,10 @@ static int hwthread_get_symbol_list_to_lookup(symbol_table_elem_t *symbol_list[]
 static int hwthread_target_for_threadid(struct connection *connection, int64_t thread_id, struct target **p_target)
 {
 	struct target *target = get_target_from_connection(connection);
-	struct target_list *head;
-	struct target *curr;
 
-	if (target->smp) {
-		/* Find the thread with that thread_id */
-		curr = NULL;
-		for (head = target->head; head != NULL; head = head->next) {
-			curr = head->target;
-
-			if (thread_id == threadid_from_target(curr))
-				break;
-		}
-
-		if (head == NULL)
-			return ERROR_FAIL;
-	} else {
-		curr = target;
-		if (thread_id != threadid_from_target(curr))
-			return ERROR_FAIL;
-	}
+	struct target *curr = find_thread(target, thread_id);
+	if (curr == NULL)
+		return ERROR_FAIL;
 
 	*p_target = curr;
 
@@ -312,6 +355,7 @@ static int hwthread_thread_packet(struct connection *connection, const char *pac
 	int64_t current_threadid;
 
 	if (packet[0] == 'H' && packet[1] == 'g') {
+		/* Never reached, because this case is handled by rtos_thread_packet(). */
 		sscanf(packet, "Hg%16" SCNx64, &current_threadid);
 
 		if (current_threadid > 0) {
diff --git a/src/rtos/rtos.c b/src/rtos/rtos.c
index da0a503..4dcc54f 100644
--- a/src/rtos/rtos.c
+++ b/src/rtos/rtos.c
@@ -462,6 +462,7 @@ static int rtos_put_gdb_reg_list(struct connection *connection,
 	return ERROR_OK;
 }
 
+/** Look through all registers to find this register. */
 int rtos_get_gdb_reg(struct connection *connection, int reg_num)
 {
 	struct target *target = get_target_from_connection(connection);
@@ -473,19 +474,31 @@ int rtos_get_gdb_reg(struct connection *connection, int reg_num)
 		struct rtos_reg *reg_list;
 		int num_regs;
 
-		LOG_DEBUG("RTOS: getting register %d for thread 0x%" PRIx64
-				  ", target->rtos->current_thread=0x%" PRIx64 "\r\n",
+		LOG_DEBUG("getting register %d for thread 0x%" PRIx64
+				  ", target->rtos->current_thread=0x%" PRIx64,
 										reg_num,
 										current_threadid,
 										target->rtos->current_thread);
 
-		int retval = target->rtos->type->get_thread_reg_list(target->rtos,
-				current_threadid,
-				&reg_list,
-				&num_regs);
-		if (retval != ERROR_OK) {
-			LOG_ERROR("RTOS: failed to get register list");
-			return retval;
+		int retval;
+		if (target->rtos->type->get_thread_reg) {
+			reg_list = calloc(1, sizeof(*reg_list));
+			num_regs = 1;
+			retval = target->rtos->type->get_thread_reg(target->rtos,
+					current_threadid, reg_num, &reg_list[0]);
+			if (retval != ERROR_OK) {
+				LOG_ERROR("RTOS: failed to get register %d", reg_num);
+				return retval;
+			}
+		} else {
+			retval = target->rtos->type->get_thread_reg_list(target->rtos,
+					current_threadid,
+					&reg_list,
+					&num_regs);
+			if (retval != ERROR_OK) {
+				LOG_ERROR("RTOS: failed to get register list");
+				return retval;
+			}
 		}
 
 		for (int i = 0; i < num_regs; ++i) {
@@ -501,6 +514,7 @@ int rtos_get_gdb_reg(struct connection *connection, int reg_num)
 	return ERROR_FAIL;
 }
 
+/** Return a list of general registers. */
 int rtos_get_gdb_reg_list(struct connection *connection)
 {
 	struct target *target = get_target_from_connection(connection);
@@ -534,6 +548,20 @@ int rtos_get_gdb_reg_list(struct connection *connection)
 	return ERROR_FAIL;
 }
 
+int rtos_set_reg(struct connection *connection, int reg_num,
+		uint8_t *reg_value)
+{
+	struct target *target = get_target_from_connection(connection);
+	int64_t current_threadid = target->rtos->current_threadid;
+	if ((target->rtos != NULL) &&
+			(target->rtos->type->set_reg != NULL) &&
+			(current_threadid != -1) &&
+			(current_threadid != 0)) {
+		return target->rtos->type->set_reg(target->rtos, reg_num, reg_value);
+	}
+	return ERROR_FAIL;
+}
+
 int rtos_generic_stack_read(struct target *target,
 	const struct rtos_register_stacking *stacking,
 	int64_t stack_ptr,
diff --git a/src/rtos/rtos.h b/src/rtos/rtos.h
index b346047..517b321 100644
--- a/src/rtos/rtos.h
+++ b/src/rtos/rtos.h
@@ -20,6 +20,7 @@
 #define OPENOCD_RTOS_RTOS_H
 
 #include "server/server.h"
+#include "target/target.h"
 #include <jim-nvp.h>
 
 typedef int64_t threadid_t;
@@ -49,7 +50,9 @@ struct rtos {
 	symbol_table_elem_t *symbols;
 	struct target *target;
 	/*  add a context variable instead of global variable */
+	/* The thread currently selected by gdb. */
 	int64_t current_threadid;
+	/* The currently selected thread according to the target. */
 	threadid_t current_thread;
 	struct thread_detail *thread_details;
 	int thread_count;
@@ -70,11 +73,15 @@ struct rtos_type {
 	int (*create)(struct target *target);
 	int (*smp_init)(struct target *target);
 	int (*update_threads)(struct rtos *rtos);
+	/** Return a list of general registers, with their values filled out. */
 	int (*get_thread_reg_list)(struct rtos *rtos, int64_t thread_id,
 			struct rtos_reg **reg_list, int *num_regs);
+	int (*get_thread_reg)(struct rtos *rtos, int64_t thread_id,
+			uint32_t reg_num, struct rtos_reg *reg);
 	int (*get_symbol_list_to_lookup)(symbol_table_elem_t *symbol_list[]);
 	int (*clean)(struct target *target);
 	char * (*ps_command)(struct target *target);
+	int (*set_reg)(struct rtos *rtos, uint32_t reg_num, uint8_t *reg_value);
 };
 
 struct stack_register_offset {
@@ -104,6 +111,8 @@ struct rtos_register_stacking {
 #define GDB_THREAD_PACKET_NOT_CONSUMED (-40)
 
 int rtos_create(Jim_GetOptInfo *goi, struct target *target);
+int rtos_set_reg(struct connection *connection, int reg_num,
+		uint8_t *reg_value);
 int rtos_generic_stack_read(struct target *target,
 		const struct rtos_register_stacking *stacking,
 		int64_t stack_ptr,
diff --git a/src/server/gdb_server.c b/src/server/gdb_server.c
index 95e6c04..dc912c9 100644
--- a/src/server/gdb_server.c
+++ b/src/server/gdb_server.c
@@ -724,7 +724,7 @@ static int gdb_output(struct command_context *context, const char *line)
 static void gdb_signal_reply(struct target *target, struct connection *connection)
 {
 	struct gdb_connection *gdb_connection = connection->priv;
-	char sig_reply[45];
+	char sig_reply[65];
 	char stop_reason[20];
 	char current_thread[25];
 	int sig_reply_len;
@@ -735,17 +735,25 @@ static void gdb_signal_reply(struct target *target, struct connection *connectio
 	if (target->debug_reason == DBG_REASON_EXIT) {
 		sig_reply_len = snprintf(sig_reply, sizeof(sig_reply), "W00");
 	} else {
+		struct target *ct;
+		if (target->rtos != NULL) {
+			target->rtos->current_threadid = target->rtos->current_thread;
+			target->rtos->gdb_target_for_threadid(connection, target->rtos->current_threadid, &ct);
+		} else {
+			ct = target;
+		}
+
 		if (gdb_connection->ctrl_c) {
 			signal_var = 0x2;
 		} else
-			signal_var = gdb_last_signal(target);
+			signal_var = gdb_last_signal(ct);
 
 		stop_reason[0] = '\0';
-		if (target->debug_reason == DBG_REASON_WATCHPOINT) {
+		if (ct->debug_reason == DBG_REASON_WATCHPOINT) {
 			enum watchpoint_rw hit_wp_type;
 			target_addr_t hit_wp_address;
 
-			if (watchpoint_hit(target, &hit_wp_type, &hit_wp_address) == ERROR_OK) {
+			if (watchpoint_hit(ct, &hit_wp_type, &hit_wp_address) == ERROR_OK) {
 
 				switch (hit_wp_type) {
 					case WPT_WRITE:
@@ -767,15 +775,9 @@ static void gdb_signal_reply(struct target *target, struct connection *connectio
 		}
 
 		current_thread[0] = '\0';
-		if (target->rtos != NULL) {
-			struct target *ct;
-			snprintf(current_thread, sizeof(current_thread), "thread:%016" PRIx64 ";",
+		if (target->rtos != NULL)
+			snprintf(current_thread, sizeof(current_thread), "thread:%" PRIx64 ";",
 					target->rtos->current_thread);
-			target->rtos->current_threadid = target->rtos->current_thread;
-			target->rtos->gdb_target_for_threadid(connection, target->rtos->current_threadid, &ct);
-			if (!gdb_connection->ctrl_c)
-				signal_var = gdb_last_signal(ct);
-		}
 
 		sig_reply_len = snprintf(sig_reply, sizeof(sig_reply), "T%2.2x%s%s",
 				signal_var, stop_reason, current_thread);
@@ -1306,7 +1308,7 @@ static int gdb_get_register_packet(struct connection *connection,
 	if ((target->rtos != NULL) && (ERROR_OK == rtos_get_gdb_reg(connection, reg_num)))
 		return ERROR_OK;
 
-	retval = target_get_gdb_reg_list(target, &reg_list, &reg_list_size,
+	retval = target_get_gdb_reg_list_noread(target, &reg_list, &reg_list_size,
 			REG_CLASS_ALL);
 	if (retval != ERROR_OK)
 		return gdb_error(connection, retval);
@@ -1342,37 +1344,49 @@ static int gdb_set_register_packet(struct connection *connection,
 {
 	struct target *target = get_target_from_connection(connection);
 	char *separator;
-	uint8_t *bin_buf;
 	int reg_num = strtoul(packet + 1, &separator, 16);
 	struct reg **reg_list;
 	int reg_list_size;
 	int retval;
 
+#ifdef _DEBUG_GDB_IO_
 	LOG_DEBUG("-");
+#endif
 
-	retval = target_get_gdb_reg_list(target, &reg_list, &reg_list_size,
+	if (*separator != '=') {
+		LOG_ERROR("GDB 'set register packet', but no '=' following the register number");
+		return ERROR_SERVER_REMOTE_CLOSED;
+	}
+	size_t chars = strlen(separator + 1);
+	uint8_t *bin_buf = malloc(chars / 2);
+	gdb_target_to_reg(target, separator + 1, chars, bin_buf);
+
+	if ((target->rtos != NULL) &&
+			(ERROR_OK == rtos_set_reg(connection, reg_num, bin_buf))) {
+		free(bin_buf);
+		gdb_put_packet(connection, "OK", 2);
+		return ERROR_OK;
+	}
+
+	retval = target_get_gdb_reg_list_noread(target, &reg_list, &reg_list_size,
 			REG_CLASS_ALL);
-	if (retval != ERROR_OK)
+	if (retval != ERROR_OK) {
+		free(bin_buf);
 		return gdb_error(connection, retval);
+	}
 
 	if (reg_list_size <= reg_num) {
 		LOG_ERROR("gdb requested a non-existing register");
+		free(bin_buf);
+		free(reg_list);
 		return ERROR_SERVER_REMOTE_CLOSED;
 	}
 
-	if (*separator != '=') {
-		LOG_ERROR("GDB 'set register packet', but no '=' following the register number");
-		return ERROR_SERVER_REMOTE_CLOSED;
-	}
-
-	/* convert from GDB-string (target-endian) to hex-string (big-endian) */
-	bin_buf = malloc(DIV_ROUND_UP(reg_list[reg_num]->size, 8));
-	int chars = (DIV_ROUND_UP(reg_list[reg_num]->size, 8) * 2);
-
-	if ((unsigned int)chars != strlen(separator + 1)) {
-		LOG_ERROR("gdb sent %zu bits for a %d-bit register (%s)",
-				strlen(separator + 1) * 4, chars * 4, reg_list[reg_num]->name);
+	if (chars != (DIV_ROUND_UP(reg_list[reg_num]->size, 8) * 2)) {
+		LOG_ERROR("gdb sent %d bits for a %d-bit register (%s)",
+				(int) chars * 4, reg_list[reg_num]->size, reg_list[reg_num]->name);
 		free(bin_buf);
+		free(reg_list);
 		return ERROR_SERVER_REMOTE_CLOSED;
 	}
 
@@ -1642,7 +1656,7 @@ static int gdb_breakpoint_watchpoint_packet(struct connection *connection,
 	char *separator;
 	int retval;
 
-	LOG_DEBUG("-");
+	LOG_DEBUG("[%d]", target->coreid);
 
 	type = strtoul(packet + 1, &separator, 16);
 
@@ -2208,7 +2222,7 @@ static int gdb_generate_target_description(struct target *target, char **tdesc_o
 
 	arch_defined_types = calloc(1, sizeof(char *));
 
-	retval = target_get_gdb_reg_list(target, &reg_list,
+	retval = target_get_gdb_reg_list_noread(target, &reg_list,
 			&reg_list_size, REG_CLASS_ALL);
 
 	if (retval != ERROR_OK) {
@@ -2396,10 +2410,11 @@ static int gdb_target_description_supported(struct target *target, int *supporte
 
 	char const *architecture = target_get_gdb_arch(target);
 
-	retval = target_get_gdb_reg_list(target, &reg_list,
+	retval = target_get_gdb_reg_list_noread(target, &reg_list,
 			&reg_list_size, REG_CLASS_ALL);
 	if (retval != ERROR_OK) {
 		LOG_ERROR("get register list failed");
+		reg_list = NULL;
 		goto error;
 	}
 
@@ -2791,13 +2806,11 @@ static bool gdb_handle_vcont_packet(struct connection *connection, const char *p
 
 				if (parse[0] == 'c') {
 					parse += 1;
-					packet_size -= 1;
 
 					/* check if thread-id follows */
 					if (parse[0] == ':') {
 						int64_t tid;
 						parse += 1;
-						packet_size -= 1;
 
 						tid = strtoll(parse, &endp, 16);
 						if (tid == thread_id) {
@@ -2887,10 +2900,9 @@ static int gdb_v_packet(struct connection *connection,
 		char const *packet, int packet_size)
 {
 	struct gdb_connection *gdb_connection = connection->priv;
-	struct target *target;
 	int result;
 
-	target = get_target_from_connection(connection);
+	struct target *target = get_target_from_connection(connection);
 
 	if (strncmp(packet, "vCont", 5) == 0) {
 		bool handled;
diff --git a/src/target/register.c b/src/target/register.c
index 5352d2f..4ddda6e 100644
--- a/src/target/register.c
+++ b/src/target/register.c
@@ -36,6 +36,29 @@
  * may be separate registers associated with debug or trace modules.
  */
 
+struct reg *register_get_by_number(struct reg_cache *first,
+		uint32_t reg_num, bool search_all)
+{
+	unsigned i;
+	struct reg_cache *cache = first;
+
+	while (cache) {
+		for (i = 0; i < cache->num_regs; i++) {
+			if (cache->reg_list[i].exist == false)
+				continue;
+			if (cache->reg_list[i].number == reg_num)
+				return &(cache->reg_list[i]);
+		}
+
+		if (search_all)
+			cache = cache->next;
+		else
+			break;
+	}
+
+	return NULL;
+}
+
 struct reg *register_get_by_name(struct reg_cache *first,
 		const char *name, bool search_all)
 {
diff --git a/src/target/register.h b/src/target/register.h
index 32c1f39..7c53d6e 100644
--- a/src/target/register.h
+++ b/src/target/register.h
@@ -159,6 +159,8 @@ struct reg_arch_type {
 	int (*set)(struct reg *reg, uint8_t *buf);
 };
 
+struct reg *register_get_by_number(struct reg_cache *first,
+		uint32_t reg_num, bool search_all);
 struct reg *register_get_by_name(struct reg_cache *first,
 		const char *name, bool search_all);
 struct reg_cache **register_get_last_cache_p(struct reg_cache **first);
diff --git a/src/target/target.c b/src/target/target.c
index 380a9fc..0af8dd2 100644
--- a/src/target/target.c
+++ b/src/target/target.c
@@ -1224,6 +1224,17 @@ int target_get_gdb_reg_list(struct target *target,
 	return target->type->get_gdb_reg_list(target, reg_list, reg_list_size, reg_class);
 }
 
+int target_get_gdb_reg_list_noread(struct target *target,
+		struct reg **reg_list[], int *reg_list_size,
+		enum target_register_class reg_class)
+{
+	if (target->type->get_gdb_reg_list_noread &&
+			target->type->get_gdb_reg_list_noread(target, reg_list,
+				reg_list_size, reg_class) == ERROR_OK)
+		return ERROR_OK;
+	return target_get_gdb_reg_list(target, reg_list, reg_list_size, reg_class);
+}
+
 bool target_supports_gdb_connection(struct target *target)
 {
 	/*
@@ -1593,8 +1604,9 @@ int target_call_event_callbacks(struct target *target, enum target_event event)
 		target_call_event_callbacks(target, TARGET_EVENT_GDB_HALT);
 	}
 
-	LOG_DEBUG("target event %i (%s)", event,
-			Jim_Nvp_value2name_simple(nvp_target_event, event)->name);
+	LOG_DEBUG("target event %i (%s) for core %d", event,
+			Jim_Nvp_value2name_simple(nvp_target_event, event)->name,
+			target->coreid);
 
 	target_handle_event(target, event);
 
diff --git a/src/target/target.h b/src/target/target.h
index 65494af..8dde03d 100644
--- a/src/target/target.h
+++ b/src/target/target.h
@@ -502,6 +502,16 @@ int target_get_gdb_reg_list(struct target *target,
 		enum target_register_class reg_class);
 
 /**
+ * Obtain the registers for GDB, but don't read register values from the
+ * target.
+ *
+ * This routine is a wrapper for target->type->get_gdb_reg_list_noread.
+ */
+int target_get_gdb_reg_list_noread(struct target *target,
+		struct reg **reg_list[], int *reg_list_size,
+		enum target_register_class reg_class);
+
+/**
  * Check if @a target allows GDB connections.
  *
  * Some target do not implement the necessary code required by GDB.
diff --git a/src/target/target_type.h b/src/target/target_type.h
index 95745c9..4bdea72 100644
--- a/src/target/target_type.h
+++ b/src/target/target_type.h
@@ -111,6 +111,13 @@ struct target_type {
 	int (*get_gdb_reg_list)(struct target *target, struct reg **reg_list[],
 			int *reg_list_size, enum target_register_class reg_class);
 
+	/**
+	 * Same as get_gdb_reg_list, but doesn't read the register values.
+	 * */
+	int (*get_gdb_reg_list_noread)(struct target *target,
+			struct reg **reg_list[], int *reg_list_size,
+			enum target_register_class reg_class);
+
 	/* target memory access
 	* size: 1 = byte (8bit), 2 = half-word (16bit), 4 = word (32bit)
 	* count: number of items of <size>

--