From: Ilya Leoshkevich <iii@linux.ibm.com>

The upcoming follow-fork-mode child support requires knowing when
fork() is about to happen in order to initialize its state. Add a hook
for that.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-Id: <20240219141628.246823-5-iii@linux.ibm.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240305121005.3528075-6-alex.bennee@linaro.org>

diff --git a/include/gdbstub/user.h b/include/gdbstub/user.h
index 68b6534130c..e33f8d9a9a6 100644
--- a/include/gdbstub/user.h
+++ b/include/gdbstub/user.h
@@ -45,6 +45,11 @@ static inline int gdb_handlesig(CPUState *cpu, int sig)
  */
 void gdb_signalled(CPUArchState *as, int sig);
 
+/**
+ * gdbserver_fork_start() - inform gdb of the upcoming fork()
+ */
+void gdbserver_fork_start(void);
+
 /**
  * gdbserver_fork() - disable gdb stub for child processes.
  * @cs: CPU
diff --git a/bsd-user/main.c b/bsd-user/main.c
index e39eef3040f..517c6b3ec2f 100644
--- a/bsd-user/main.c
+++ b/bsd-user/main.c
@@ -113,6 +113,7 @@ void fork_start(void)
     start_exclusive();
     cpu_list_lock();
     mmap_fork_start();
+    gdbserver_fork_start();
 }
 
 void fork_end(int child)
diff --git a/gdbstub/user.c b/gdbstub/user.c
index 3ce20b7bbfc..536fb43b03e 100644
--- a/gdbstub/user.c
+++ b/gdbstub/user.c
@@ -356,6 +356,10 @@ int gdbserver_start(const char *port_or_path)
     return -1;
 }
 
+void gdbserver_fork_start(void)
+{
+}
+
 static void disable_gdbstub(CPUState *thread_cpu)
 {
     CPUState *cpu;
diff --git a/linux-user/main.c b/linux-user/main.c
index 699da773714..755c566d6d2 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -145,6 +145,7 @@ void fork_start(void)
     mmap_fork_start();
     cpu_list_lock();
     qemu_plugin_user_prefork_lock();
+    gdbserver_fork_start();
 }
 
 void fork_end(int child)
-- 
2.39.2