gdb_server: add per target option "-gdb-port"

The argument passed to global config command "gdb_port" is usually,
but not always, a TCP port number. In case of multiple targets, this
numeric value is used as the first port of a set of consecutive TCP
ports assigned one per target.
If the argument is not a numeric value (e.g. "pipe", "disabled", ...)
then incrementing it for the next target has no sense.

Add the option "-gdb-port number" to the commands "target create" and
"$target_name configure" to override, for the specific target, the
general global configuration.

This permits to use a per target "-gdb-port disabled", when no gdb
port is required for that specific target.

It also makes possible to choose a custom TCP port number for each
target, overriding the usual sequence of consecutive port numbers.

Change-Id: I3b9a1910b28ab4bc757e839d0e5d08ffc29f7ab4
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/4530
Tested-by: jenkins
Reviewed-by: Christopher Head <chead@zaber.com>
Reviewed-by: Matthias Welwarsky <matthias@welwarsky.de>

doc/openocd.texi

@@ -2114,6 +2114,7 @@ In such cases, just specify the relevant port number as "disabled".
 If you disable all access through TCP/IP, you will need to
 use the command line @option{-pipe} option.
 
+@anchor{gdb_port}
 @deffn {Command} gdb_port [number]
 @cindex GDB server
 Normally gdb listens to a TCP/IP port, but GDB can also
@@ -2139,11 +2140,15 @@ The GDB port for the first target will be the base port, the
 second target will listen on gdb_port + 1, and so on.
 When not specified during the configuration stage,
 the port @var{number} defaults to 3333.
+When @var{number} is not a numeric value, incrementing it to compute
+the next port number does not work. In this case, specify the proper
+@var{number} for each target by using the option @code{-gdb-port} of the
+commands @command{target create} or @command{$target_name configure}.
+@xref{gdbportoverride,,option -gdb-port}.
 
 Note: when using "gdb_port pipe", increasing the default remote timeout in
 gdb (with 'set remotetimeout') is recommended. An insufficient timeout may
 cause initialization to fail with "Unknown remote qXfer reply: OK".
-
 @end deffn
 
 @deffn {Command} tcl_port [number]
@@ -4458,6 +4463,13 @@ to the target. Currently, only the @code{aarch64} target makes use of this optio
 where it is a mandatory configuration for the target run control.
 @xref{armcrosstrigger,,ARM Cross-Trigger Interface},
 for instruction on how to declare and control a CTI instance.
+
+@anchor{gdbportoverride}
+@item @code{-gdb-port} @var{number} -- see command @command{gdb_port} for the
+possible values of the parameter @var{number}, which are not only numeric values.
+Use this option to override, for this target only, the global parameter set with
+command @command{gdb_port}.
+@xref{gdb_port,,command gdb_port}.
 @end itemize
 @end deffn
 

src/server/gdb_server.c

@@ -3373,6 +3373,8 @@ static int gdb_target_start(struct target *target, const char *port)
 	if (NULL == gdb_service)
 		return -ENOMEM;
 
+	LOG_DEBUG("starting gdb server for %s on %s", target_name(target), port);
+
 	gdb_service->target = target;
 	gdb_service->core[0] = -1;
 	gdb_service->core[1] = -1;
@@ -3398,16 +3400,30 @@ static int gdb_target_start(struct target *target, const char *port)
 
 static int gdb_target_add_one(struct target *target)
 {
+	/*  one gdb instance per smp list */
+	if ((target->smp) && (target->gdb_service))
+		return ERROR_OK;
+
+	if (target->gdb_port_override) {
+		if (strcmp(target->gdb_port_override, "disabled") == 0) {
+			LOG_INFO("gdb port disabled");
+			return ERROR_OK;
+		}
+		return gdb_target_start(target, target->gdb_port_override);
+	}
+
 	if (strcmp(gdb_port, "disabled") == 0) {
 		LOG_INFO("gdb port disabled");
 		return ERROR_OK;
 	}
 
-	/*  one gdb instance per smp list */
-	if ((target->smp) && (target->gdb_service))
-		return ERROR_OK;
 	int retval = gdb_target_start(target, gdb_port_next);
 	if (retval == ERROR_OK) {
+		/* save the port number so can be queried with
+		 * $target_name cget -gdb-port
+		 */
+		target->gdb_port_override = strdup(gdb_port_next);
+
 		long portnumber;
 		/* If we can parse the port number
 		 * then we increment the port number for the next target.
@@ -3432,11 +3448,6 @@ static int gdb_target_add_one(struct target *target)
 
 int gdb_target_add_all(struct target *target)
 {
-	if (strcmp(gdb_port, "disabled") == 0) {
-		LOG_INFO("gdb server disabled");
-		return ERROR_OK;
-	}
-
 	if (NULL == target) {
 		LOG_WARNING("gdb services need one or more targets defined");
 		return ERROR_OK;

src/target/target.c

@@ -1927,6 +1927,7 @@ static void target_destroy(struct target *target)
 		target->smp = 0;
 	}
 
+	free(target->gdb_port_override);
 	free(target->type);
 	free(target->trace_info);
 	free(target->fileio_info);
@@ -4537,6 +4538,7 @@ enum target_cfg_param {
 	TCFG_DBGBASE,
 	TCFG_RTOS,
 	TCFG_DEFER_EXAMINE,
+	TCFG_GDB_PORT,
 };
 
 static Jim_Nvp nvp_config_opts[] = {
@@ -4552,6 +4554,7 @@ static Jim_Nvp nvp_config_opts[] = {
 	{ .name = "-dbgbase",          .value = TCFG_DBGBASE },
 	{ .name = "-rtos",             .value = TCFG_RTOS },
 	{ .name = "-defer-examine",    .value = TCFG_DEFER_EXAMINE },
+	{ .name = "-gdb-port",         .value = TCFG_GDB_PORT },
 	{ .name = NULL, .value = -1 }
 };
 
@@ -4839,6 +4842,20 @@ no_params:
 			/* loop for more */
 			break;
 
+		case TCFG_GDB_PORT:
+			if (goi->isconfigure) {
+				const char *s;
+				e = Jim_GetOpt_String(goi, &s, NULL);
+				if (e != JIM_OK)
+					return e;
+				target->gdb_port_override = strdup(s);
+			} else {
+				if (goi->argc != 0)
+					goto no_params;
+			}
+			Jim_SetResultString(goi->interp, target->gdb_port_override ? : "undefined", -1);
+			/* loop for more */
+			break;
 		}
 	} /* while (goi->argc) */
 
@@ -5613,6 +5630,8 @@ static int target_create(Jim_GetOptInfo *goi)
 	target->rtos = NULL;
 	target->rtos_auto_detect = false;
 
+	target->gdb_port_override = NULL;
+
 	/* Do the rest as "configure" options */
 	goi->isconfigure = 1;
 	e = target_configure(goi, target);
@@ -5635,6 +5654,7 @@ static int target_create(Jim_GetOptInfo *goi)
 	}
 
 	if (e != JIM_OK) {
+		free(target->gdb_port_override);
 		free(target->type);
 		free(target);
 		return e;
@@ -5652,6 +5672,7 @@ static int target_create(Jim_GetOptInfo *goi)
 		e = (*(target->type->target_create))(target, goi->interp);
 		if (e != ERROR_OK) {
 			LOG_DEBUG("target_create failed");
+			free(target->gdb_port_override);
 			free(target->type);
 			free(target->cmd_name);
 			free(target);

src/target/target.h

@@ -206,6 +206,8 @@ struct target {
 	/* file-I/O information for host to do syscall */
 	struct gdb_fileio_info *fileio_info;
 
+	char *gdb_port_override;			/* target-specific override for gdb_port */
+
 	/* The semihosting information, extracted from the target. */
 	struct semihosting *semihosting;
 };