[PATCH V16 7/7] gdbstub: Add helper function to unregister GDB register space

[Salil Mehta]

Add common function to help unregister the GDB register space. This shall be
done in context to the CPU unrealization.

Note: These are common functions exported to arch specific code. For example,
for ARM this code is being referred in associated arch specific patch-set:

Link: 
https://lore.kernel.org/qemu-devel/20230926103654.34424-1-salil.mehta@huawei.com/

Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
Tested-by: Vishnu Pajjuri <vishnu@os.amperecomputing.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Tested-by: Xianglai Li <lixianglai@loongson.cn>
Tested-by: Miguel Luis <miguel.luis@oracle.com>
Reviewed-by: Shaoqin Huang <shahuang@redhat.com>
Reviewed-by: Vishnu Pajjuri <vishnu@os.amperecomputing.com>
Tested-by: Zhao Liu <zhao1.liu@intel.com>
Acked-by: Igor Mammedov <imammedo@redhat.com>
---
 gdbstub/gdbstub.c      | 13 +++++++++++++
 hw/core/cpu-common.c   |  5 ++++-
 include/exec/gdbstub.h |  6 ++++++
 3 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/gdbstub/gdbstub.c b/gdbstub/gdbstub.c
index b9ad0a063e..5da17d6530 100644
--- a/gdbstub/gdbstub.c
+++ b/gdbstub/gdbstub.c
@@ -618,6 +618,19 @@ void gdb_register_coprocessor(CPUState *cpu,
     }
 }
 
+void gdb_unregister_coprocessor_all(CPUState *cpu)
+{
+    /*
+     * Safe to nuke everything. GDBRegisterState::xml is static const char so
+     * it won't be freed
+     */
+    g_array_free(cpu->gdb_regs, true);
+
+    cpu->gdb_regs = NULL;
+    cpu->gdb_num_regs = 0;
+    cpu->gdb_num_g_regs = 0;
+}
+
 static void gdb_process_breakpoint_remove_all(GDBProcess *p)
 {
     CPUState *cpu = gdb_get_first_cpu_in_process(p);
diff --git a/hw/core/cpu-common.c b/hw/core/cpu-common.c
index b19e1fdacf..f6d62df34f 100644
--- a/hw/core/cpu-common.c
+++ b/hw/core/cpu-common.c
@@ -281,7 +281,10 @@ static void cpu_common_finalize(Object *obj)
         g_free(cpu->plugin_state);
     }
 #endif
-    g_array_free(cpu->gdb_regs, TRUE);
+    /* If cleanup didn't happen in context to gdb_unregister_coprocessor_all */
+    if (cpu->gdb_regs) {
+        g_array_free(cpu->gdb_regs, TRUE);
+    }
     qemu_lockcnt_destroy(&cpu->in_ioctl_lock);
     qemu_mutex_destroy(&cpu->work_mutex);
     qemu_cond_destroy(cpu->halt_cond);
diff --git a/include/exec/gdbstub.h b/include/exec/gdbstub.h
index 1bd2c4ec2a..d73f424f56 100644
--- a/include/exec/gdbstub.h
+++ b/include/exec/gdbstub.h
@@ -40,6 +40,12 @@ void gdb_register_coprocessor(CPUState *cpu,
                               gdb_get_reg_cb get_reg, gdb_set_reg_cb set_reg,
                               const GDBFeature *feature, int g_pos);
 
+/**
+ * gdb_unregister_coprocessor_all() - unregisters supplemental set of registers
+ * @cpu - the CPU associated with registers
+ */
+void gdb_unregister_coprocessor_all(CPUState *cpu);
+
 /**
  * gdbserver_start: start the gdb server
  * @port_or_device: connection spec for gdb
-- 
2.34.1