rtos/hwthread: add hardware-thread pseudo rtos

This patch adds "hwthread", a pseudo rtos that represents cpu cores
in an SMP system as threads to gdb. This allows to debug SMP
system kernels in a more sensible manner and removes the current
atrocities of switching gdb manually between CPU cores to update
the context.

Change-Id: Ib781c6c34097689d21d9e02011e4d74a4a742379
Signed-off-by: Matthias Welwarsky <matthias.welwarsky@sysgo.com>
Reviewed-on: http://openocd.zylin.com/3999
Tested-by: jenkins
Reviewed-by: Tim Newsome <tim@sifive.com>
Reviewed-by: Matthias Welwarsky <matthias@welwarsky.de>
Reviewed-by: Graham Sanderson <graham.sanderson@gmail.com>

4 files changed, 417 insertions, 51 deletions

diff --git a/doc/openocd.texi b/doc/openocd.texi
index 2e04182..bbb9075 100644
--- a/doc/openocd.texi
+++ b/doc/openocd.texi
@@ -10199,55 +10199,6 @@ and GDB would require stopping the target to get the prompt back.
 Do not use this mode under an IDE like Eclipse as it caches values of
 previously shown varibles.
 
-@anchor{usingopenocdsmpwithgdb}
-@section Using OpenOCD SMP with GDB
-@cindex SMP
-For SMP support following GDB serial protocol packet have been defined :
-@itemize @bullet
-@item j - smp status request
-@item J - smp set request
-@end itemize
-
-OpenOCD implements :
-@itemize @bullet
-@item @option{jc} packet for reading core id displayed by
-GDB connection. Reply is @option{XXXXXXXX} (8 hex digits giving core id) or
- @option{E01} for target not smp.
-@item @option{JcXXXXXXXX} (8 hex digits) packet for setting core id displayed at next GDB continue
-(core id -1 is reserved for returning to normal resume mode). Reply @option{E01}
-for target not smp or @option{OK} on success.
-@end itemize
-
-Handling of this packet within GDB can be done :
-@itemize @bullet
-@item by the creation of an internal variable (i.e @option{_core}) by mean
-of function allocate_computed_value allowing following GDB command.
-@example
-set $_core 1
-#Jc01 packet is sent
-print $_core
-#jc packet is sent and result is affected in $
-@end example
-
-@item by the usage of GDB maintenance command as described in following example (2 cpus in SMP with
-core id 0 and 1 @pxref{definecputargetsworkinginsmp,,Define CPU targets working in SMP}).
-
-@example
-# toggle0 : force display of coreid 0
-define toggle0
-maint packet Jc0
-continue
-main packet Jc-1
-end
-# toggle1 : force display of coreid 1
-define toggle1
-maint packet Jc1
-continue
-main packet Jc-1
-end
-@end example
-@end itemize
-
 @section RTOS Support
 @cindex RTOS Support
 @anchor{gdbrtossupport}
@@ -10278,12 +10229,11 @@ Currently supported rtos's include:
 @item @option{mqx}
 @item @option{uCOS-III}
 @item @option{nuttx}
+@item @option{hwthread} (This is not an actual RTOS. @xref{usingopenocdsmpwithgdb,,Using OpenOCD SMP with GDB}.)
 @end itemize
 
-@quotation Note
 Before an RTOS can be detected, it must export certain symbols; otherwise, it cannot
 be used by OpenOCD. Below is a list of the required symbols for each supported RTOS.
-@end quotation
 
 @table @code
 @item eCos symbols
@@ -10330,6 +10280,72 @@ contrib/rtos-helpers/FreeRTOS-openocd.c
 contrib/rtos-helpers/uCOS-III-openocd.c
 @end table
 
+@anchor{usingopenocdsmpwithgdb}
+@section Using OpenOCD SMP with GDB
+@cindex SMP
+@cindex RTOS
+@cindex hwthread
+OpenOCD includes a pseudo RTOS called @emph{hwthread} that presents CPU cores
+("hardware threads") in an SMP system as threads to GDB. With this extension,
+GDB can be used to inspect the state of an SMP system in a natural way.
+After halting the system, using the GDB command @command{info threads} will
+list the context of each active CPU core in the system. GDB's @command{thread}
+command can be used to switch the view to a different CPU core.
+The @command{step} and @command{stepi} commands can be used to step a specific core
+while other cores are free-running or remain halted, depending on the
+scheduler-locking mode configured in GDB.
+
+@section Legacy SMP core switching support
+@quotation Note
+This method is deprecated in favor of the @emph{hwthread} pseudo RTOS.
+@end quotation
+
+For SMP support following GDB serial protocol packet have been defined :
+@itemize @bullet
+@item j - smp status request
+@item J - smp set request
+@end itemize
+
+OpenOCD implements :
+@itemize @bullet
+@item @option{jc} packet for reading core id displayed by
+GDB connection. Reply is @option{XXXXXXXX} (8 hex digits giving core id) or
+ @option{E01} for target not smp.
+@item @option{JcXXXXXXXX} (8 hex digits) packet for setting core id displayed at next GDB continue
+(core id -1 is reserved for returning to normal resume mode). Reply @option{E01}
+for target not smp or @option{OK} on success.
+@end itemize
+
+Handling of this packet within GDB can be done :
+@itemize @bullet
+@item by the creation of an internal variable (i.e @option{_core}) by mean
+of function allocate_computed_value allowing following GDB command.
+@example
+set $_core 1
+#Jc01 packet is sent
+print $_core
+#jc packet is sent and result is affected in $
+@end example
+
+@item by the usage of GDB maintenance command as described in following example (2 cpus in SMP with
+core id 0 and 1 @pxref{definecputargetsworkinginsmp,,Define CPU targets working in SMP}).
+
+@example
+# toggle0 : force display of coreid 0
+define toggle0
+maint packet Jc0
+continue
+main packet Jc-1
+end
+# toggle1 : force display of coreid 1
+define toggle1
+maint packet Jc1
+continue
+main packet Jc-1
+end
+@end example
+@end itemize
+
 @node Tcl Scripting API
 @chapter Tcl Scripting API
 @cindex Tcl Scripting API
diff --git a/src/rtos/Makefile.am b/src/rtos/Makefile.am
index bbf66a6..38adb6e 100644
--- a/src/rtos/Makefile.am
+++ b/src/rtos/Makefile.am
@@ -17,6 +17,7 @@ noinst_LTLIBRARIES += %D%/librtos.la
 	%D%/mqx.c \
 	%D%/uCOS-III.c \
 	%D%/nuttx.c \
+	%D%/hwthread.c \
 	%D%/rtos.h \
 	%D%/rtos_standard_stackings.h \
 	%D%/rtos_ecos_stackings.h \
diff --git a/src/rtos/hwthread.c b/src/rtos/hwthread.c
new file mode 100644
index 0000000..2d9e42f
--- /dev/null
+++ b/src/rtos/hwthread.c
@@ -0,0 +1,347 @@
+/***************************************************************************
+ *                                                                         *
+ *   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 "target/register.h"
+#include "rtos.h"
+#include "helper/log.h"
+#include "helper/types.h"
+#include "server/gdb_server.h"
+
+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_list(struct rtos *rtos, int64_t thread_id,
+					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);
+
+#define HW_THREAD_NAME_STR_SIZE (32)
+
+extern int rtos_thread_packet(struct connection *connection, const char *packet, int packet_size);
+
+static inline threadid_t threadid_from_target(const struct target *target)
+{
+	return target->coreid + 1;
+}
+
+const struct rtos_type hwthread_rtos = {
+	.name = "hwthread",
+	.detect_rtos = hwthread_detect_rtos,
+	.create = hwthread_create,
+	.update_threads = hwthread_update_threads,
+	.get_thread_reg_list = hwthread_get_thread_reg_list,
+	.get_symbol_list_to_lookup = hwthread_get_symbol_list_to_lookup,
+	.smp_init = hwthread_smp_init,
+};
+
+struct hwthread_params {
+	int dummy_param;
+};
+
+static int hwthread_fill_thread(struct rtos *rtos, struct target *curr, int thread_num)
+{
+	char tmp_str[HW_THREAD_NAME_STR_SIZE];
+	threadid_t tid = threadid_from_target(curr);
+
+	memset(tmp_str, 0, HW_THREAD_NAME_STR_SIZE);
+
+	/* thread-id is the core-id of this core inside the SMP group plus 1 */
+	rtos->thread_details[thread_num].threadid = tid;
+	/* create the thread name */
+	rtos->thread_details[thread_num].exists = true;
+	rtos->thread_details[thread_num].thread_name_str = strdup(target_name(curr));
+	snprintf(tmp_str, HW_THREAD_NAME_STR_SIZE-1, "state: %s", debug_reason_name(curr));
+	rtos->thread_details[thread_num].extra_info_str = strdup(tmp_str);
+
+	return ERROR_OK;
+}
+
+static int hwthread_update_threads(struct rtos *rtos)
+{
+	int threads_found = 0;
+	int thread_list_size = 0;
+	struct target_list *head;
+	struct target *target;
+	int64_t current_thread = 0;
+	enum target_debug_reason current_reason = DBG_REASON_UNDEFINED;
+
+	if (rtos == NULL)
+		return -1;
+
+	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) {
+			struct target *curr = head->target;
+
+			if (!target_was_examined(curr))
+				continue;
+
+			++thread_list_size;
+		}
+	} else
+		thread_list_size = 1;
+
+	/* create space for new thread details */
+	rtos->thread_details = malloc(sizeof(struct thread_detail) * thread_list_size);
+
+	if (target->smp) {
+		/* loop over all threads */
+		for (head = target->head; head != NULL; head = head->next) {
+			struct target *curr = head->target;
+
+			if (!target_was_examined(curr))
+				continue;
+
+			threadid_t tid = threadid_from_target(curr);
+
+			hwthread_fill_thread(rtos, curr, threads_found);
+
+			/* find an interesting thread to set as current */
+			switch (current_reason) {
+			case DBG_REASON_UNDEFINED:
+				current_reason = curr->debug_reason;
+				current_thread = tid;
+				break;
+			case DBG_REASON_SINGLESTEP:
+				/* single-step can only be overridden by itself */
+				if (curr->debug_reason == DBG_REASON_SINGLESTEP) {
+					if (tid == rtos->current_threadid)
+						current_thread = tid;
+				}
+				break;
+			case DBG_REASON_BREAKPOINT:
+				/* single-step overrides breakpoint */
+				if (curr->debug_reason == DBG_REASON_SINGLESTEP) {
+					current_reason = curr->debug_reason;
+					current_thread = tid;
+				} else
+				/* multiple breakpoints, prefer gdbs' threadid */
+				if (curr->debug_reason == DBG_REASON_BREAKPOINT) {
+					if (tid == rtos->current_threadid)
+						current_thread = tid;
+				}
+				break;
+			case DBG_REASON_WATCHPOINT:
+				/* breakpoint and single-step override watchpoint */
+				if (curr->debug_reason == DBG_REASON_SINGLESTEP ||
+						curr->debug_reason == DBG_REASON_BREAKPOINT) {
+					current_reason = curr->debug_reason;
+					current_thread = tid;
+				}
+				break;
+			case DBG_REASON_DBGRQ:
+				/* all other reasons override debug-request */
+				if (curr->debug_reason == DBG_REASON_SINGLESTEP ||
+						curr->debug_reason == DBG_REASON_WATCHPOINT ||
+						curr->debug_reason == DBG_REASON_BREAKPOINT) {
+					current_reason = curr->debug_reason;
+					current_thread = tid;
+				} else
+				if (curr->debug_reason == DBG_REASON_DBGRQ) {
+					if (tid == rtos->current_threadid)
+						current_thread = tid;
+				}
+
+				break;
+
+			default:
+				break;
+			}
+
+			threads_found++;
+		}
+	} else {
+		hwthread_fill_thread(rtos, target, threads_found);
+		current_thread = threadid_from_target(target);
+		threads_found++;
+	}
+
+	rtos->thread_count = threads_found;
+
+	/* we found an interesting thread, set it as current */
+	if (current_thread != 0)
+		rtos->current_thread = current_thread;
+	else if (rtos->current_threadid != 0)
+		rtos->current_thread = rtos->current_threadid;
+	else
+		rtos->current_thread = threadid_from_target(target);
+
+	LOG_DEBUG("%s current_thread=%i", __func__, (int)rtos->current_thread);
+	return 0;
+}
+
+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)
+{
+	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->smp) {
+		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;
+
+	}
+
+	if (!target_was_examined(curr))
+		return ERROR_FAIL;
+
+	retval = target_get_gdb_reg_list(curr, &reg_list, num_regs,
+			REG_CLASS_GENERAL);
+	if (retval != ERROR_OK)
+		return retval;
+
+	*rtos_reg_list = calloc(*num_regs, sizeof(struct rtos_reg));
+	if (*rtos_reg_list == NULL) {
+		free(reg_list);
+		return ERROR_FAIL;
+	}
+
+	for (int i = 0; i < *num_regs; 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);
+	}
+
+	free(reg_list);
+
+	return ERROR_OK;
+
+}
+
+static int hwthread_get_symbol_list_to_lookup(symbol_table_elem_t *symbol_list[])
+{
+	/* return an empty list, we don't have any symbols to look up */
+	*symbol_list = calloc(1, sizeof(symbol_table_elem_t));
+	(*symbol_list)[0].symbol_name = NULL;
+	return 0;
+}
+
+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;
+	}
+
+	*p_target = curr;
+
+	return ERROR_OK;
+}
+
+static bool hwthread_detect_rtos(struct target *target)
+{
+	/* always return 0, avoid auto-detection */
+	return false;
+}
+
+static int hwthread_thread_packet(struct connection *connection, const char *packet, int packet_size)
+{
+	struct target *target = get_target_from_connection(connection);
+
+	struct target *curr = NULL;
+	int64_t current_threadid;
+
+	if (packet[0] == 'H' && packet[1] == 'g') {
+		sscanf(packet, "Hg%16" SCNx64, &current_threadid);
+
+		if (current_threadid > 0) {
+			if (hwthread_target_for_threadid(connection, current_threadid, &curr) != ERROR_OK) {
+				LOG_ERROR("hwthread: cannot find thread id %"PRId64, current_threadid);
+				gdb_put_packet(connection, "E01", 3);
+				return ERROR_FAIL;
+			}
+			target->rtos->current_thread = current_threadid;
+		} else
+		if (current_threadid == 0 || current_threadid == -1)
+			target->rtos->current_thread = threadid_from_target(target);
+
+		target->rtos->current_threadid = current_threadid;
+
+		gdb_put_packet(connection, "OK", 2);
+		return ERROR_OK;
+	}
+
+	return rtos_thread_packet(connection, packet, packet_size);
+}
+
+static int hwthread_create(struct target *target)
+{
+	LOG_INFO("Hardware thread awareness created");
+
+	target->rtos->rtos_specific_params = NULL;
+	target->rtos->current_thread = 0;
+	target->rtos->thread_details = NULL;
+	target->rtos->gdb_target_for_threadid = hwthread_target_for_threadid;
+	target->rtos->gdb_thread_packet = hwthread_thread_packet;
+	return 0;
+}
diff --git a/src/rtos/rtos.c b/src/rtos/rtos.c
index cd2e271..da0a503 100644
--- a/src/rtos/rtos.c
+++ b/src/rtos/rtos.c
@@ -37,6 +37,7 @@ extern struct rtos_type embKernel_rtos;
 extern struct rtos_type mqx_rtos;
 extern struct rtos_type uCOS_III_rtos;
 extern struct rtos_type nuttx_rtos;
+extern struct rtos_type hwthread_rtos;
 
 static struct rtos_type *rtos_types[] = {
 	&ThreadX_rtos,
@@ -49,6 +50,7 @@ static struct rtos_type *rtos_types[] = {
 	&mqx_rtos,
 	&uCOS_III_rtos,
 	&nuttx_rtos,
+	&hwthread_rtos,
 	NULL
 };