[Qemu-devel] [PATCH v2 01/15] gdbstub: introduce GDB processes

[Luc Michel <luc.michel@greensocs.com>]

Add a structure GDBProcess that represent processes from the GDB
semantic point of view.

CPUs can be split into different processes, by grouping them under a QOM
container named after the GDB_CPU_GROUP_NAME macro (`gdb-group[*]').
Each occurrence of such a container implies the existence of the
corresponding process in the GDB stub. The gdb_cpu_group_container_get()
function can be used to create a new container.

When no such container are found, all the CPUs are put in a unique GDB
process (create_unique_process()). This is also the case when compiled
in user mode, where multi-processes do not make much sense for now.

Signed-off-by: Luc Michel <luc.michel@greensocs.com>
---
 include/exec/gdbstub.h |  8 +++++
 gdbstub.c              | 67 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 75 insertions(+)

diff --git a/include/exec/gdbstub.h b/include/exec/gdbstub.h
index 08363969c1..a3e4159bf4 100644
--- a/include/exec/gdbstub.h
+++ b/include/exec/gdbstub.h
@@ -1,8 +1,10 @@
 #ifndef GDBSTUB_H
 #define GDBSTUB_H
 
+#include "qom/object.h"
+
 #define DEFAULT_GDBSTUB_PORT "1234"
 
 /* GDB breakpoint/watchpoint types */
 #define GDB_BREAKPOINT_SW        0
 #define GDB_BREAKPOINT_HW        1
@@ -129,6 +131,12 @@ void gdbserver_cleanup(void);
 extern bool gdb_has_xml;
 
 /* in gdbstub-xml.c, generated by scripts/feature_to_c.sh */
 extern const char *const xml_builtin[][2];
 
+#define GDB_CPU_GROUP_NAME  "gdb-group"
+
+static inline Object *gdb_cpu_group_container_get(Object *parent)
+{
+    return container_get(parent, "/" GDB_CPU_GROUP_NAME "[*]");
+}
 #endif
diff --git a/gdbstub.c b/gdbstub.c
index d6ab95006c..5c86218f49 100644
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -295,10 +295,17 @@ typedef struct GDBRegisterState {
     gdb_reg_cb set_reg;
     const char *xml;
     struct GDBRegisterState *next;
 } GDBRegisterState;
 
+typedef struct GDBProcess {
+    uint32_t pid;
+    bool attached;
+
+    char target_xml[1024];
+} GDBProcess;
+
 enum RSState {
     RS_INACTIVE,
     RS_IDLE,
     RS_GETLINE,
     RS_GETLINE_ESC,
@@ -323,10 +330,13 @@ typedef struct GDBState {
     int running_state;
 #else
     CharBackend chr;
     Chardev *mon_chr;
 #endif
+    bool multiprocess;
+    GDBProcess *processes;
+    int process_num;
     char syscall_buf[256];
     gdb_syscall_complete_cb current_syscall_cb;
 } GDBState;
 
 /* By default use no IRQs and no timers while single stepping so as to
@@ -1750,10 +1760,24 @@ void gdb_exit(CPUArchState *env, int code)
 #ifndef CONFIG_USER_ONLY
   qemu_chr_fe_deinit(&s->chr, true);
 #endif
 }
 
+/*
+ * Create a unique process containing all the CPUs.
+ */
+static void create_unique_process(GDBState *s)
+{
+    GDBProcess *process;
+
+    s->processes = g_malloc0(sizeof(GDBProcess));
+    s->process_num = 1;
+    process = &s->processes[0];
+
+    process->pid = 1;
+}
+
 #ifdef CONFIG_USER_ONLY
 int
 gdb_handlesig(CPUState *cpu, int sig)
 {
     GDBState *s;
@@ -1847,10 +1871,11 @@ static bool gdb_accept(void)
     }
 
     s = g_malloc0(sizeof(GDBState));
     s->c_cpu = first_cpu;
     s->g_cpu = first_cpu;
+    create_unique_process(s);
     s->fd = fd;
     gdb_has_xml = false;
 
     gdbserver_state = s;
     return true;
@@ -2003,10 +2028,48 @@ static const TypeInfo char_gdb_type_info = {
     .name = TYPE_CHARDEV_GDB,
     .parent = TYPE_CHARDEV,
     .class_init = char_gdb_class_init,
 };
 
+static void create_processes(GDBState *s)
+{
+    Object *container;
+    int i = 0;
+    char process_str[16];
+
+    container = object_resolve_path(GDB_CPU_GROUP_NAME "[0]", NULL);
+
+    while (container) {
+        s->processes = g_renew(GDBProcess, s->processes, i + 1);
+
+        GDBProcess *process = &s->processes[i];
+
+        /* GDB process IDs -1 and 0 are reserved */
+        process->pid = i + 1;
+        process->attached = false;
+        process->target_xml[0] = '\0';
+
+        i++;
+        snprintf(process_str, sizeof(process_str), GDB_CPU_GROUP_NAME "[%d]", i);
+        container = object_resolve_path(process_str, NULL);
+    }
+
+    if (!s->processes) {
+        /* No CPU group specified by the machine */
+        create_unique_process(s);
+    } else {
+        s->process_num = i;
+    }
+}
+
+static void cleanup_processes(GDBState *s)
+{
+    g_free(s->processes);
+    s->process_num = 0;
+    s->processes = NULL;
+}
+
 int gdbserver_start(const char *device)
 {
     trace_gdbstub_op_start(device);
 
     GDBState *s;
@@ -2055,15 +2118,19 @@ int gdbserver_start(const char *device)
                                    NULL, &error_abort);
         monitor_init(mon_chr, 0);
     } else {
         qemu_chr_fe_deinit(&s->chr, true);
         mon_chr = s->mon_chr;
+        cleanup_processes(s);
         memset(s, 0, sizeof(GDBState));
         s->mon_chr = mon_chr;
     }
     s->c_cpu = first_cpu;
     s->g_cpu = first_cpu;
+
+    create_processes(s);
+
     if (chr) {
         qemu_chr_fe_init(&s->chr, chr, &error_abort);
         qemu_chr_fe_set_handlers(&s->chr, gdb_chr_can_receive, gdb_chr_receive,
                                  gdb_chr_event, NULL, NULL, NULL, true);
     }
-- 
2.19.0