gdbstub: add support for vAttach packets

Add support for the vAttach packets. In multiprocess mode, GDB sends
them to attach to additional processes.

Signed-off-by: Luc Michel <luc.michel@greensocs.com>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20181207090135.7651-13-luc.michel@greensocs.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 35 insertions, 0 deletions

diff --git a/gdbstub.c b/gdbstub.c
index 9b6b4d20a0..d80af955ce 100644
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -1348,6 +1348,41 @@ static int gdb_handle_packet(GDBState *s, const char *line_buf)
                 goto unknown_command;
             }
             break;
+        } else if (strncmp(p, "Attach;", 7) == 0) {
+            unsigned long pid;
+
+            p += 7;
+
+            if (qemu_strtoul(p, &p, 16, &pid)) {
+                put_packet(s, "E22");
+                break;
+            }
+
+            process = gdb_get_process(s, pid);
+
+            if (process == NULL) {
+                put_packet(s, "E22");
+                break;
+            }
+
+            cpu = get_first_cpu_in_process(s, process);
+
+            if (cpu == NULL) {
+                /* Refuse to attach an empty process */
+                put_packet(s, "E22");
+                break;
+            }
+
+            process->attached = true;
+
+            s->g_cpu = cpu;
+            s->c_cpu = cpu;
+
+            snprintf(buf, sizeof(buf), "T%02xthread:%s;", GDB_SIGNAL_TRAP,
+                     gdb_fmt_thread_id(s, cpu, thread_id, sizeof(thread_id)));
+
+            put_packet(s, buf);
+            break;
         } else {
             goto unknown_command;
         }