gdb_server: avoid gdb server for virtual targets

Virtual targets, like mem_ap, do not or cannot implement the required
functionality to accept a GDB connection. In the case of mem_ap, the
method get_gdb_reg_list() is missing and a following connection from
gdb causes OpenOCD to segfault.
OpenOCD opens a GDB port for each target; it's always possible to
connect, by mistake, GDB to one virtual target.

Add a method to check if the target supports GDB connections (for the
moment just checking if get_gdb_reg_list is implemented).
Skip opening a gdb server for every targets that don't support GDB
connections.

Change-Id: Ia439a43efe1a9adbb1771cd9d252db8ffa32eb9d
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/4676
Tested-by: jenkins
Reviewed-by: Matthias Welwarsky <matthias@welwarsky.de>

diff --git a/src/server/gdb_server.c b/src/server/gdb_server.c
index 2375e951184150cec339d02ee0fadd4293f38f97..a45127360a3d387df55e8f8e687535ef4993df7c 100644 (file)
--- a/src/server/gdb_server.c
+++ b/src/server/gdb_server.c
@@ -3404,6 +3404,12 @@ static int gdb_target_add_one(struct target *target)
        if ((target->smp) && (target->gdb_service))
                return ERROR_OK;
 
+       /* skip targets that cannot handle a gdb connections (e.g. mem_ap) */
+       if (!target_supports_gdb_connection(target)) {
+               LOG_DEBUG("skip gdb server for target %s", target_name(target));
+               return ERROR_OK;
+       }
+
        if (target->gdb_port_override) {
                if (strcmp(target->gdb_port_override, "disabled") == 0) {
                        LOG_INFO("gdb port disabled");

diff --git a/src/target/target.c b/src/target/target.c
index 060fbdca5af8e7eaf6713c7a8d3df338c2538b07..478c39d1bba3a6f2051a9f46fbf4db1003f4775c 100644 (file)
--- a/src/target/target.c
+++ b/src/target/target.c
@@ -1205,6 +1205,16 @@ int target_get_gdb_reg_list(struct target *target,
 {
        return target->type->get_gdb_reg_list(target, reg_list, reg_list_size, reg_class);
 }
+
+bool target_supports_gdb_connection(struct target *target)
+{
+       /*
+        * based on current code, we can simply exclude all the targets that
+        * don't provide get_gdb_reg_list; this could change with new targets.
+        */
+       return !!target->type->get_gdb_reg_list;
+}
+
 int target_step(struct target *target,
                int current, target_addr_t address, int handle_breakpoints)
 {

diff --git a/src/target/target.h b/src/target/target.h
index c3137a08c5dd5083dbb6ed5b60a081063d0ac263..fe7e1a7db8e18993f0832ebce8460e013cd9a2e2 100644 (file)
--- a/src/target/target.h
+++ b/src/target/target.h
@@ -481,6 +481,13 @@ int target_get_gdb_reg_list(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.
+ */
+bool target_supports_gdb_connection(struct target *target);
+
 /**
  * Step the target.
  *