rtos: add support for uC/OS-III

This patch introduces RTOS support for uC/OS-III. Currently, only
FPU-less ARM Cortex-M targets are supported. Due to the configurability
of the RTOS, an OpenOCD-specific file must be linked along with the
project to determine the correct offsets within the OS_TCB structure.

In addition to the above, a crash was fixed in rtos_get_gdb_reg_list
such that RTOS support could be used between resets without restarting
OpenOCD and support for the Hg packet was cleaned up.

Change-Id: Ide004a689e6b886185df665c00fb644629eb31d1
Signed-off-by: Steven Stallion <stallion@squareup.com>
Reviewed-on: http://openocd.zylin.com/3556
Tested-by: jenkins
Reviewed-by: Paul Fertser <fercerpav@gmail.com>

7 files changed, 653 insertions, 10 deletions

diff --git a/contrib/rtos-helpers/uCOS-III-openocd.c b/contrib/rtos-helpers/uCOS-III-openocd.c
new file mode 100644
index 0000000..9037334
--- /dev/null
+++ b/contrib/rtos-helpers/uCOS-III-openocd.c
@@ -0,0 +1,32 @@
+/*
+ * uC/OS-III does not provide a fixed layout for OS_TCB, which makes it
+ * impossible to determine the appropriate offsets within the structure
+ * unaided. A priori knowledge of offsets based on os_dbg.c is tied to a
+ * specific release and thusly, brittle. The constants defined below
+ * provide the neccessary information OpenOCD needs to provide support
+ * in the most robust manner possible.
+ *
+ * This file should be linked along with the project to enable RTOS
+ * support for uC/OS-III.
+ */
+
+#include <os.h>
+
+#if OS_CFG_DBG_EN == 0
+#error "OS_CFG_DBG_EN is required to enable RTOS support for OpenOCD"
+#endif
+
+#define OFFSET_OF(type, member) ((CPU_SIZE_T)&(((type *)0)->member))
+
+#ifdef __GNUC__
+#define USED __attribute__((used))
+#else
+#define USED
+#endif
+
+const CPU_SIZE_T USED openocd_OS_TCB_StkPtr_offset = OFFSET_OF(OS_TCB, StkPtr);
+const CPU_SIZE_T USED openocd_OS_TCB_NamePtr_offset = OFFSET_OF(OS_TCB, NamePtr);
+const CPU_SIZE_T USED openocd_OS_TCB_TaskState_offset = OFFSET_OF(OS_TCB, TaskState);
+const CPU_SIZE_T USED openocd_OS_TCB_Prio_offset = OFFSET_OF(OS_TCB, Prio);
+const CPU_SIZE_T USED openocd_OS_TCB_DbgPrevPtr_offset = OFFSET_OF(OS_TCB, DbgPrevPtr);
+const CPU_SIZE_T USED openocd_OS_TCB_DbgNextPtr_offset = OFFSET_OF(OS_TCB, DbgNextPtr);
diff --git a/doc/openocd.texi b/doc/openocd.texi
index 497a20b..372683a 100644
--- a/doc/openocd.texi
+++ b/doc/openocd.texi
@@ -4123,7 +4123,8 @@ The value should normally correspond to a static mapping for the
 @anchor{rtostype}
 @item @code{-rtos} @var{rtos_type} -- enable rtos support for target,
 @var{rtos_type} can be one of @option{auto}|@option{eCos}|@option{ThreadX}|
-@option{FreeRTOS}|@option{linux}|@option{ChibiOS}|@option{embKernel}|@option{mqx}
+@option{FreeRTOS}|@option{linux}|@option{ChibiOS}|@option{embKernel}|@option{mqx}|
+@option{uCOS-III}
 @xref{gdbrtossupport,,RTOS Support}.
 
 @item @code{-defer-examine} -- skip target examination at initial JTAG chain
@@ -8833,6 +8834,7 @@ Currently supported rtos's include:
 @item @option{ChibiOS}
 @item @option{embKernel}
 @item @option{mqx}
+@item @option{uCOS-III}
 @end itemize
 
 @quotation Note
@@ -8866,10 +8868,12 @@ Rtos::sCurrentTask, Rtos::sListReady, Rtos::sListSleep,
 Rtos::sListSuspended, Rtos::sMaxPriorities, Rtos::sCurrentTaskCount.
 @item mqx symbols
 _mqx_kernel_data, MQX_init_struct.
+@item uC/OS-III symbols
+OSRunning, OSTCBCurPtr, OSTaskDbgListPtr, OSTaskQty
 @end table
 
 For most RTOS supported the above symbols will be exported by default. However for
-some, eg. FreeRTOS, extra steps must be taken.
+some, eg. FreeRTOS and uC/OS-III, extra steps must be taken.
 
 These RTOSes may require additional OpenOCD-specific file to be linked
 along with the project:
@@ -8877,6 +8881,8 @@ along with the project:
 @table @code
 @item FreeRTOS
 contrib/rtos-helpers/FreeRTOS-openocd.c
+@item uC/OS-III
+contrib/rtos-helpers/uCOS-III-openocd.c
 @end table
 
 @node Tcl Scripting API
diff --git a/src/rtos/Makefile.am b/src/rtos/Makefile.am
index fdca394..a9122b2 100644
--- a/src/rtos/Makefile.am
+++ b/src/rtos/Makefile.am
@@ -20,8 +20,8 @@ include $(top_srcdir)/common.mk
 
 METASOURCES = AUTO
 noinst_LTLIBRARIES = librtos.la
-noinst_HEADERS = rtos.h rtos_standard_stackings.h rtos_ecos_stackings.h linux_header.h rtos_chibios_stackings.h rtos_embkernel_stackings.h rtos_mqx_stackings.h
-librtos_la_SOURCES = rtos.c rtos_standard_stackings.c rtos_ecos_stackings.c  rtos_chibios_stackings.c rtos_embkernel_stackings.c rtos_mqx_stackings.c FreeRTOS.c ThreadX.c eCos.c linux.c ChibiOS.c embKernel.c mqx.c
+noinst_HEADERS = rtos.h rtos_standard_stackings.h rtos_ecos_stackings.h linux_header.h rtos_chibios_stackings.h rtos_embkernel_stackings.h rtos_mqx_stackings.h rtos_ucos_iii_stackings.h
+librtos_la_SOURCES = rtos.c rtos_standard_stackings.c rtos_ecos_stackings.c  rtos_chibios_stackings.c rtos_embkernel_stackings.c rtos_mqx_stackings.c rtos_ucos_iii_stackings.c FreeRTOS.c ThreadX.c eCos.c linux.c ChibiOS.c embKernel.c mqx.c uCOS-III.c
 
 librtos_la_CFLAGS =
 if IS_MINGW
diff --git a/src/rtos/rtos.c b/src/rtos/rtos.c
index aa8efbe..785fc61 100644
--- a/src/rtos/rtos.c
+++ b/src/rtos/rtos.c
@@ -34,6 +34,7 @@ extern struct rtos_type Linux_os;
 extern struct rtos_type ChibiOS_rtos;
 extern struct rtos_type embKernel_rtos;
 extern struct rtos_type mqx_rtos;
+extern struct rtos_type uCOS_III_rtos;
 
 static struct rtos_type *rtos_types[] = {
 	&ThreadX_rtos,
@@ -43,6 +44,7 @@ static struct rtos_type *rtos_types[] = {
 	&ChibiOS_rtos,
 	&embKernel_rtos,
 	&mqx_rtos,
+	&uCOS_III_rtos,
 	NULL
 };
 
@@ -400,9 +402,14 @@ int rtos_thread_packet(struct connection *connection, char const *packet, int pa
 	} else if (packet[0] == 'H') {	/* Set current thread ( 'c' for step and continue, 'g' for
 					 * all other operations ) */
 		if ((packet[1] == 'g') && (target->rtos != NULL)) {
-			sscanf(packet, "Hg%16" SCNx64, &target->rtos->current_threadid);
-			LOG_DEBUG("RTOS: GDB requested to set current thread to 0x%" PRIx64 "\r\n",
-										target->rtos->current_threadid);
+			threadid_t threadid;
+			sscanf(packet, "Hg%16" SCNx64, &threadid);
+			LOG_DEBUG("RTOS: GDB requested to set current thread to 0x%" PRIx64, threadid);
+			/* threadid of 0 indicates target should choose */
+			if (threadid == 0)
+				target->rtos->current_threadid = target->rtos->current_thread;
+			else
+				target->rtos->current_threadid = threadid;
 		}
 		gdb_put_packet(connection, "OK", 2);
 		return ERROR_OK;
@@ -426,9 +433,13 @@ int rtos_get_gdb_reg_list(struct connection *connection)
 										current_threadid,
 										target->rtos->current_thread);
 
-		target->rtos->type->get_thread_reg_list(target->rtos,
-			current_threadid,
-			&hex_reg_list);
+		int retval = target->rtos->type->get_thread_reg_list(target->rtos,
+				current_threadid,
+				&hex_reg_list);
+		if (retval != ERROR_OK) {
+			LOG_ERROR("RTOS: failed to get register list");
+			return retval;
+		}
 
 		if (hex_reg_list != NULL) {
 			gdb_put_packet(connection, hex_reg_list, strlen(hex_reg_list));
@@ -546,5 +557,7 @@ void rtos_free_threadlist(struct rtos *rtos)
 		free(rtos->thread_details);
 		rtos->thread_details = NULL;
 		rtos->thread_count = 0;
+		rtos->current_threadid = -1;
+		rtos->current_thread = 0;
 	}
 }
diff --git a/src/rtos/rtos_ucos_iii_stackings.c b/src/rtos/rtos_ucos_iii_stackings.c
new file mode 100644
index 0000000..f2f5564
--- /dev/null
+++ b/src/rtos/rtos_ucos_iii_stackings.c
@@ -0,0 +1,53 @@
+/***************************************************************************
+ *   Copyright (C) 2016 by Square, Inc.                                    *
+ *   Steven Stallion <stallion@squareup.com>                               *
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ *   This program is distributed in the hope that it will be useful,       *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU General Public License for more details.                          *
+ *                                                                         *
+ *   You should have received a copy of the GNU General Public License     *
+ *   along with this program.  If not, see <http://www.gnu.org/licenses/>. *
+ ***************************************************************************/
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "rtos.h"
+#include "rtos_standard_stackings.h"
+#include "target/armv7m.h"
+
+static const struct stack_register_offset rtos_uCOS_III_Cortex_M_stack_offsets[ARMV7M_NUM_CORE_REGS] = {
+	{ 0x20, 32 },		/* r0   */
+	{ 0x24, 32 },		/* r1   */
+	{ 0x28, 32 },		/* r2   */
+	{ 0x2c, 32 },		/* r3   */
+	{ 0x00, 32 },		/* r4   */
+	{ 0x04, 32 },		/* r5   */
+	{ 0x08, 32 },		/* r6   */
+	{ 0x0c, 32 },		/* r7   */
+	{ 0x10, 32 },		/* r8   */
+	{ 0x14, 32 },		/* r9   */
+	{ 0x18, 32 },		/* r10  */
+	{ 0x1c, 32 },		/* r11  */
+	{ 0x30, 32 },		/* r12  */
+	{ -2,   32 },		/* sp   */
+	{ 0x34, 32 },		/* lr   */
+	{ 0x38, 32 },		/* pc   */
+	{ 0x3c, 32 },		/* xPSR */
+};
+
+const struct rtos_register_stacking rtos_uCOS_III_Cortex_M_stacking = {
+	0x40,					/* stack_registers_size */
+	-1,					/* stack_growth_direction */
+	ARMV7M_NUM_CORE_REGS,			/* num_output_registers */
+	rtos_generic_stack_align8,		/* stack_alignment */
+	rtos_uCOS_III_Cortex_M_stack_offsets	/* register_offsets */
+};
diff --git a/src/rtos/rtos_ucos_iii_stackings.h b/src/rtos/rtos_ucos_iii_stackings.h
new file mode 100644
index 0000000..c462cd7
--- /dev/null
+++ b/src/rtos/rtos_ucos_iii_stackings.h
@@ -0,0 +1,30 @@
+/***************************************************************************
+ *   Copyright (C) 2016 by Square, Inc.                                    *
+ *   Steven Stallion <stallion@squareup.com>                               *
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ *   This program is distributed in the hope that it will be useful,       *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU General Public License for more details.                          *
+ *                                                                         *
+ *   You should have received a copy of the GNU General Public License     *
+ *   along with this program.  If not, see <http://www.gnu.org/licenses/>. *
+ ***************************************************************************/
+
+#ifndef OPENOCD_RTOS_RTOS_UCOS_III_STACKINGS_H
+#define OPENOCD_RTOS_RTOS_UCOS_III_STACKINGS_H
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "rtos.h"
+
+extern const struct rtos_register_stacking rtos_uCOS_III_Cortex_M_stacking;
+
+#endif /* OPENOCD_RTOS_RTOS_UCOS_III_STACKINGS_H */
diff --git a/src/rtos/uCOS-III.c b/src/rtos/uCOS-III.c
new file mode 100644
index 0000000..75cfe52
--- /dev/null
+++ b/src/rtos/uCOS-III.c
@@ -0,0 +1,509 @@
+/***************************************************************************
+ *   Copyright (C) 2016 by Square, Inc.                                    *
+ *   Steven Stallion <stallion@squareup.com>                               *
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ *   This program is distributed in the hope that it will be useful,       *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU General Public License for more details.                          *
+ *                                                                         *
+ *   You should have received a copy of the GNU General Public License     *
+ *   along with this program.  If not, see <http://www.gnu.org/licenses/>. *
+ ***************************************************************************/
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <helper/time_support.h>
+#include <jtag/jtag.h>
+#include "target/target.h"
+#include "target/target_type.h"
+#include "rtos.h"
+#include "helper/log.h"
+#include "helper/types.h"
+#include "rtos/rtos_ucos_iii_stackings.h"
+
+#ifndef UCOS_III_MAX_STRLEN
+#define UCOS_III_MAX_STRLEN 64
+#endif
+
+#ifndef UCOS_III_MAX_THREADS
+#define UCOS_III_MAX_THREADS 256
+#endif
+
+struct uCOS_III_params {
+	const char *target_name;
+	const unsigned char pointer_width;
+	symbol_address_t thread_stack_offset;
+	symbol_address_t thread_name_offset;
+	symbol_address_t thread_state_offset;
+	symbol_address_t thread_priority_offset;
+	symbol_address_t thread_prev_offset;
+	symbol_address_t thread_next_offset;
+	bool thread_offsets_updated;
+	size_t threadid_start;
+	const struct rtos_register_stacking *stacking_info;
+	size_t num_threads;
+	symbol_address_t threads[];
+};
+
+static const struct uCOS_III_params uCOS_III_params_list[] = {
+	{
+		"cortex_m",				/* target_name */
+		sizeof(uint32_t),			/* pointer_width */
+		0,					/* thread_stack_offset */
+		0,					/* thread_name_offset */
+		0,					/* thread_state_offset */
+		0,					/* thread_priority_offset */
+		0,					/* thread_prev_offset */
+		0,					/* thread_next_offset */
+		false,					/* thread_offsets_updated */
+		1,					/* threadid_start */
+		&rtos_uCOS_III_Cortex_M_stacking,	/* stacking_info */
+		0,					/* num_threads */
+	},
+};
+
+static const char * const uCOS_III_symbol_list[] = {
+	"OSRunning",
+	"OSTCBCurPtr",
+	"OSTaskDbgListPtr",
+	"OSTaskQty",
+
+	/* also see: contrib/rtos-helpers/uCOS-III-openocd.c */
+	"openocd_OS_TCB_StkPtr_offset",
+	"openocd_OS_TCB_NamePtr_offset",
+	"openocd_OS_TCB_TaskState_offset",
+	"openocd_OS_TCB_Prio_offset",
+	"openocd_OS_TCB_DbgPrevPtr_offset",
+	"openocd_OS_TCB_DbgNextPtr_offset",
+	NULL
+};
+
+enum uCOS_III_symbol_values {
+	uCOS_III_VAL_OSRunning,
+	uCOS_III_VAL_OSTCBCurPtr,
+	uCOS_III_VAL_OSTaskDbgListPtr,
+	uCOS_III_VAL_OSTaskQty,
+
+	/* also see: contrib/rtos-helpers/uCOS-III-openocd.c */
+	uCOS_III_VAL_OS_TCB_StkPtr_offset,
+	uCOS_III_VAL_OS_TCB_NamePtr_offset,
+	uCOS_III_VAL_OS_TCB_TaskState_offset,
+	uCOS_III_VAL_OS_TCB_Prio_offset,
+	uCOS_III_VAL_OS_TCB_DbgPrevPtr_offset,
+	uCOS_III_VAL_OS_TCB_DbgNextPtr_offset,
+};
+
+static const char * const uCOS_III_thread_state_list[] = {
+	"Ready",
+	"Delay",
+	"Pend",
+	"Pend Timeout",
+	"Suspended",
+	"Delay Suspended",
+	"Pend Suspended",
+	"Pend Timeout Suspended",
+};
+
+static int uCOS_III_find_or_create_thread(struct rtos *rtos, symbol_address_t thread_address,
+		threadid_t *threadid)
+{
+	struct uCOS_III_params *params = rtos->rtos_specific_params;
+	size_t thread_index;
+
+	for (thread_index = 0; thread_index < params->num_threads; thread_index++)
+		if (params->threads[thread_index] == thread_address)
+			goto found;
+
+	if (params->num_threads == UCOS_III_MAX_THREADS) {
+		LOG_WARNING("uCOS-III: too many threads; increase UCOS_III_MAX_THREADS");
+		return ERROR_FAIL;
+	}
+
+	params->threads[thread_index] = thread_address;
+	params->num_threads++;
+found:
+	*threadid = thread_index + params->threadid_start;
+	return ERROR_OK;
+}
+
+static int uCOS_III_find_thread_address(struct rtos *rtos, threadid_t threadid,
+		symbol_address_t *thread_address)
+{
+	struct uCOS_III_params *params = rtos->rtos_specific_params;
+	size_t thread_index;
+
+	thread_index = threadid - params->threadid_start;
+	if (thread_index >= params->num_threads) {
+		LOG_ERROR("uCOS-III: failed to find thread address");
+		return ERROR_FAIL;
+	}
+
+	*thread_address = params->threads[thread_index];
+	return ERROR_OK;
+}
+
+static int uCOS_III_find_last_thread_address(struct rtos *rtos, symbol_address_t *thread_address)
+{
+	struct uCOS_III_params *params = rtos->rtos_specific_params;
+	int retval;
+
+	/* read the thread list head */
+	symbol_address_t thread_list_address = 0;
+
+	retval = target_read_memory(rtos->target,
+				    rtos->symbols[uCOS_III_VAL_OSTaskDbgListPtr].address,
+				    params->pointer_width,
+				    1,
+				    (void *)&thread_list_address);
+	if (retval != ERROR_OK) {
+		LOG_ERROR("uCOS-III: failed to read thread list address");
+		return retval;
+	}
+
+	/* advance to end of thread list */
+	do {
+		*thread_address = thread_list_address;
+
+		retval = target_read_memory(rtos->target,
+					    thread_list_address + params->thread_next_offset,
+					    params->pointer_width,
+					    1,
+					    (void *)&thread_list_address);
+		if (retval != ERROR_OK) {
+			LOG_ERROR("uCOS-III: failed to read next thread address");
+			return retval;
+		}
+	} while (thread_list_address != 0);
+
+	return ERROR_OK;
+}
+
+static int uCOS_III_update_thread_offsets(struct rtos *rtos)
+{
+	struct uCOS_III_params *params = rtos->rtos_specific_params;
+
+	if (params->thread_offsets_updated)
+		return ERROR_OK;
+
+	const struct thread_offset_map {
+		enum uCOS_III_symbol_values symbol_value;
+		symbol_address_t *thread_offset;
+	} thread_offset_maps[] = {
+		{
+			uCOS_III_VAL_OS_TCB_StkPtr_offset,
+			&params->thread_stack_offset,
+		},
+		{
+			uCOS_III_VAL_OS_TCB_NamePtr_offset,
+			&params->thread_name_offset,
+		},
+		{
+			uCOS_III_VAL_OS_TCB_TaskState_offset,
+			&params->thread_state_offset,
+		},
+		{
+			uCOS_III_VAL_OS_TCB_Prio_offset,
+			&params->thread_priority_offset,
+		},
+		{
+			uCOS_III_VAL_OS_TCB_DbgPrevPtr_offset,
+			&params->thread_prev_offset,
+		},
+		{
+			uCOS_III_VAL_OS_TCB_DbgNextPtr_offset,
+			&params->thread_next_offset,
+		},
+	};
+
+	for (size_t i = 0; i < ARRAY_SIZE(thread_offset_maps); i++) {
+		const struct thread_offset_map *thread_offset_map = &thread_offset_maps[i];
+
+		int retval = target_read_memory(rtos->target,
+						rtos->symbols[thread_offset_map->symbol_value].address,
+						params->pointer_width,
+						1,
+						(void *)thread_offset_map->thread_offset);
+		if (retval != ERROR_OK) {
+			LOG_ERROR("uCOS-III: failed to read thread offset");
+			return retval;
+		}
+	}
+
+	params->thread_offsets_updated = true;
+	return ERROR_OK;
+}
+
+static int uCOS_III_detect_rtos(struct target *target)
+{
+	return target->rtos->symbols != NULL &&
+	    target->rtos->symbols[uCOS_III_VAL_OSRunning].address != 0;
+}
+
+static int uCOS_III_reset_handler(struct target *target, enum target_reset_mode reset_mode, void *priv)
+{
+	struct uCOS_III_params *params = target->rtos->rtos_specific_params;
+
+	params->thread_offsets_updated = false;
+	params->num_threads = 0;
+
+	return ERROR_OK;
+}
+
+static int uCOS_III_create(struct target *target)
+{
+	struct uCOS_III_params *params;
+
+	for (size_t i = 0; i < ARRAY_SIZE(uCOS_III_params_list); i++)
+		if (strcmp(uCOS_III_params_list[i].target_name, target->type->name) == 0) {
+			params = malloc(sizeof(*params) +
+			    UCOS_III_MAX_THREADS * sizeof(*params->threads));
+			if (params == NULL) {
+				LOG_ERROR("uCOS-III: out of memory");
+				return ERROR_FAIL;
+			}
+
+			memcpy(params, &uCOS_III_params_list[i], sizeof(uCOS_III_params_list[i]));
+			target->rtos->rtos_specific_params = (void *)params;
+
+			target_register_reset_callback(uCOS_III_reset_handler, NULL);
+
+			return ERROR_OK;
+		}
+
+	LOG_ERROR("uCOS-III: target not supported: %s", target->type->name);
+	return ERROR_FAIL;
+}
+
+static int uCOS_III_update_threads(struct rtos *rtos)
+{
+	struct uCOS_III_params *params = rtos->rtos_specific_params;
+	int retval;
+
+	/* free previous thread details */
+	rtos_free_threadlist(rtos);
+
+	/* verify RTOS is running */
+	uint8_t rtos_running;
+
+	retval = target_read_u8(rtos->target,
+				rtos->symbols[uCOS_III_VAL_OSRunning].address,
+				&rtos_running);
+	if (retval != ERROR_OK) {
+		LOG_ERROR("uCOS-III: failed to read RTOS running");
+		return retval;
+	}
+
+	if (!rtos_running) {
+		rtos->thread_details = calloc(1, sizeof(struct thread_detail));
+		if (rtos->thread_details == NULL) {
+			LOG_ERROR("uCOS-III: out of memory");
+			return ERROR_FAIL;
+		}
+
+		rtos->thread_count = 1;
+		rtos->thread_details->threadid = 0;
+		rtos->thread_details->exists = true;
+		rtos->current_thread = 0;
+
+		return ERROR_OK;
+	}
+
+	/* update thread offsets */
+	retval = uCOS_III_update_thread_offsets(rtos);
+	if (retval != ERROR_OK) {
+		LOG_ERROR("uCOS-III: failed to update thread offsets");
+		return retval;
+	}
+
+	/* read current thread address */
+	symbol_address_t current_thread_address = 0;
+
+	retval = target_read_memory(rtos->target,
+				    rtos->symbols[uCOS_III_VAL_OSTCBCurPtr].address,
+				    params->pointer_width,
+				    1,
+				    (void *)&current_thread_address);
+	if (retval != ERROR_OK) {
+		LOG_ERROR("uCOS-III: failed to read current thread address");
+		return retval;
+	}
+
+	/* read number of tasks */
+	retval = target_read_u16(rtos->target,
+				 rtos->symbols[uCOS_III_VAL_OSTaskQty].address,
+				 (void *)&rtos->thread_count);
+	if (retval != ERROR_OK) {
+		LOG_ERROR("uCOS-III: failed to read thread count");
+		return retval;
+	}
+
+	rtos->thread_details = calloc(rtos->thread_count, sizeof(struct thread_detail));
+	if (rtos->thread_details == NULL) {
+		LOG_ERROR("uCOS-III: out of memory");
+		return ERROR_FAIL;
+	}
+
+	/*
+	 * uC/OS-III adds tasks in LIFO order; advance to the end of the
+	 * list and work backwards to preserve the intended order.
+	 */
+	symbol_address_t thread_address = 0;
+
+	retval = uCOS_III_find_last_thread_address(rtos, &thread_address);
+	if (retval != ERROR_OK) {
+		LOG_ERROR("uCOS-III: failed to find last thread address");
+		return retval;
+	}
+
+	for (int i = 0; i < rtos->thread_count; i++) {
+		struct thread_detail *thread_detail = &rtos->thread_details[i];
+		char thread_str_buffer[UCOS_III_MAX_STRLEN + 1];
+
+		/* find or create new threadid */
+		retval = uCOS_III_find_or_create_thread(rtos,
+							thread_address,
+							&thread_detail->threadid);
+		if (retval != ERROR_OK) {
+			LOG_ERROR("uCOS-III: failed to find or create thread");
+			return retval;
+		}
+
+		if (thread_address == current_thread_address)
+			rtos->current_thread = thread_detail->threadid;
+
+		thread_detail->exists = true;
+
+		/* read thread name */
+		symbol_address_t thread_name_address = 0;
+
+		retval = target_read_memory(rtos->target,
+					    thread_address + params->thread_name_offset,
+					    params->pointer_width,
+					    1,
+					    (void *)&thread_name_address);
+		if (retval != ERROR_OK) {
+			LOG_ERROR("uCOS-III: failed to name address");
+			return retval;
+		}
+
+		retval = target_read_buffer(rtos->target,
+					    thread_name_address,
+					    sizeof(thread_str_buffer),
+					    (void *)thread_str_buffer);
+		if (retval != ERROR_OK) {
+			LOG_ERROR("uCOS-III: failed to read thread name");
+			return retval;
+		}
+
+		thread_str_buffer[sizeof(thread_str_buffer) - 1] = '\0';
+		thread_detail->thread_name_str = strdup(thread_str_buffer);
+
+		/* read thread extra info */
+		uint8_t thread_state;
+		uint8_t thread_priority;
+
+		retval = target_read_u8(rtos->target,
+					thread_address + params->thread_state_offset,
+					&thread_state);
+		if (retval != ERROR_OK) {
+			LOG_ERROR("uCOS-III: failed to read thread state");
+			return retval;
+		}
+
+		retval = target_read_u8(rtos->target,
+					thread_address + params->thread_priority_offset,
+					&thread_priority);
+		if (retval != ERROR_OK) {
+			LOG_ERROR("uCOS-III: failed to read thread priority");
+			return retval;
+		}
+
+		const char *thread_state_str;
+
+		if (thread_state < ARRAY_SIZE(uCOS_III_thread_state_list))
+			thread_state_str = uCOS_III_thread_state_list[thread_state];
+		else
+			thread_state_str = "Unknown";
+
+		snprintf(thread_str_buffer, sizeof(thread_str_buffer), "State: %s, Priority: %d",
+			 thread_state_str, thread_priority);
+		thread_detail->extra_info_str = strdup(thread_str_buffer);
+
+		/* read previous thread address */
+		retval = target_read_memory(rtos->target,
+					    thread_address + params->thread_prev_offset,
+					    params->pointer_width,
+					    1,
+					    (void *)&thread_address);
+		if (retval != ERROR_OK) {
+			LOG_ERROR("uCOS-III: failed to read previous thread address");
+			return retval;
+		}
+	}
+
+	return ERROR_OK;
+}
+
+static int uCOS_III_get_thread_reg_list(struct rtos *rtos, threadid_t threadid, char **hex_reg_list)
+{
+	struct uCOS_III_params *params = rtos->rtos_specific_params;
+	int retval;
+
+	/* find thread address for threadid */
+	symbol_address_t thread_address = 0;
+
+	retval = uCOS_III_find_thread_address(rtos, threadid, &thread_address);
+	if (retval != ERROR_OK) {
+		LOG_ERROR("uCOS-III: failed to find thread address");
+		return retval;
+	}
+
+	/* read thread stack address */
+	symbol_address_t stack_address = 0;
+
+	retval = target_read_memory(rtos->target,
+				    thread_address + params->thread_stack_offset,
+				    params->pointer_width,
+				    1,
+				    (void *)&stack_address);
+	if (retval != ERROR_OK) {
+		LOG_ERROR("uCOS-III: failed to read stack address");
+		return retval;
+	}
+
+	return rtos_generic_stack_read(rtos->target,
+				       params->stacking_info,
+				       stack_address,
+				       hex_reg_list);
+}
+
+static int uCOS_III_get_symbol_list_to_lookup(symbol_table_elem_t *symbol_list[])
+{
+	*symbol_list = calloc(ARRAY_SIZE(uCOS_III_symbol_list), sizeof(symbol_table_elem_t));
+	if (*symbol_list == NULL) {
+		LOG_ERROR("uCOS-III: out of memory");
+		return ERROR_FAIL;
+	}
+
+	for (size_t i = 0; i < ARRAY_SIZE(uCOS_III_symbol_list); i++)
+		(*symbol_list)[i].symbol_name = uCOS_III_symbol_list[i];
+
+	return ERROR_OK;
+}
+
+const struct rtos_type uCOS_III_rtos = {
+	.name = "uCOS-III",
+	.detect_rtos = uCOS_III_detect_rtos,
+	.create = uCOS_III_create,
+	.update_threads = uCOS_III_update_threads,
+	.get_thread_reg_list = uCOS_III_get_thread_reg_list,
+	.get_symbol_list_to_lookup = uCOS_III_get_symbol_list_to_lookup,
+};