gdbstub: Allow specifying a reason in stop packets

The upcoming syscall catchpoint support needs to send stop packets with
an associated reason to GDB. Add an extra parameter to gdb_handlesig()
for that, and rename it to gdb_handlesig_reason(). Provide a
compatibility wrapper with an old name.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-Id: <20240202152506.279476-3-iii@linux.ibm.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240207163812.3231697-12-alex.bennee@linaro.org>

gdbstub/user.c

@@ -121,7 +121,7 @@ void gdb_qemu_exit(int code)
     exit(code);
 }
 
-int gdb_handlesig(CPUState *cpu, int sig)
+int gdb_handlesig_reason(CPUState *cpu, int sig, const char *reason)
 {
     char buf[256];
     int n;
@@ -141,6 +141,9 @@ int gdb_handlesig(CPUState *cpu, int sig)
                             "T%02xthread:", gdb_target_signal_to_gdb(sig));
             gdb_append_thread_id(cpu, gdbserver_state.str_buf);
             g_string_append_c(gdbserver_state.str_buf, ';');
+            if (reason) {
+                g_string_append(gdbserver_state.str_buf, reason);
+            }
             gdb_put_strbuf();
             gdbserver_state.allow_stop_reply = false;
         }

include/gdbstub/user.h

@@ -10,9 +10,10 @@
 #define GDBSTUB_USER_H
 
 /**
- * gdb_handlesig() - yield control to gdb
+ * gdb_handlesig_reason() - yield control to gdb
  * @cpu: CPU
  * @sig: if non-zero, the signal number which caused us to stop
+ * @reason: stop reason for stop reply packet or NULL
  *
  * This function yields control to gdb, when a user-mode-only target
  * needs to stop execution. If @sig is non-zero, then we will send a
@@ -24,7 +25,18 @@
  * or 0 if no signal should be delivered, ie the signal that caused
  * us to stop should be ignored.
  */
-int gdb_handlesig(CPUState *, int);
+int gdb_handlesig_reason(CPUState *, int, const char *);
+
+/**
+ * gdb_handlesig() - yield control to gdb
+ * @cpu CPU
+ * @sig: if non-zero, the signal number which caused us to stop
+ * @see gdb_handlesig_reason()
+ */
+static inline int gdb_handlesig(CPUState *cpu, int sig)
+{
+    return gdb_handlesig_reason(cpu, sig, NULL);
+}
 
 /**
  * gdb_signalled() - inform remote gdb of sig exit