{linux,bsd}-user: Pass pid to fork_end()

The upcoming follow-fork-mode child support requires knowing the child
pid. Pass it down.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-Id: <20240219141628.246823-6-iii@linux.ibm.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240305121005.3528075-7-alex.bennee@linaro.org>

bsd-user/freebsd/os-proc.h

@@ -208,7 +208,7 @@ static inline abi_long do_freebsd_fork(void *cpu_env)
      */
     set_second_rval(cpu_env, child_flag);
 
-    fork_end(child_flag);
+    fork_end(ret);
 
     return ret;
 }
@@ -252,7 +252,7 @@ static inline abi_long do_freebsd_rfork(void *cpu_env, abi_long flags)
      * value: 0 for parent process, 1 for child process.
      */
     set_second_rval(cpu_env, child_flag);
-    fork_end(child_flag);
+    fork_end(ret);
 
     return ret;
 
@@ -285,7 +285,7 @@ static inline abi_long do_freebsd_pdfork(void *cpu_env, abi_ulong target_fdp,
      * value: 0 for parent process, 1 for child process.
      */
     set_second_rval(cpu_env, child_flag);
-    fork_end(child_flag);
+    fork_end(ret);
 
     return ret;
 }

bsd-user/main.c

@@ -116,8 +116,10 @@ void fork_start(void)
     gdbserver_fork_start();
 }
 
-void fork_end(int child)
+void fork_end(pid_t pid)
 {
+    bool child = pid == 0;
+
     if (child) {
         CPUState *cpu, *next_cpu;
         /*

bsd-user/qemu.h

@@ -192,7 +192,7 @@ void cpu_loop(CPUArchState *env);
 char *target_strerror(int err);
 int get_osversion(void);
 void fork_start(void);
-void fork_end(int child);
+void fork_end(pid_t pid);
 
 #include "qemu/log.h"
 

linux-user/main.c

@@ -148,8 +148,10 @@ void fork_start(void)
     gdbserver_fork_start();
 }
 
-void fork_end(int child)
+void fork_end(pid_t pid)
 {
+    bool child = pid == 0;
+
     qemu_plugin_user_postfork(child);
     mmap_fork_end(child);
     if (child) {

linux-user/syscall.c

@@ -6669,7 +6669,7 @@ static int do_fork(CPUArchState *env, unsigned int flags, abi_ulong newsp,
         if (ret == 0) {
             /* Child Process.  */
             cpu_clone_regs_child(env, newsp, flags);
-            fork_end(1);
+            fork_end(ret);
             /* There is a race condition here.  The parent process could
                theoretically read the TID in the child process before the child
                tid is set.  This would require using either ptrace
@@ -6700,8 +6700,8 @@ static int do_fork(CPUArchState *env, unsigned int flags, abi_ulong newsp,
                 }
 #endif
                 put_user_u32(pid_fd, parent_tidptr);
-                }
-            fork_end(0);
+            }
+            fork_end(ret);
         }
         g_assert(!cpu_in_exclusive_context(cpu));
     }

linux-user/user-internals.h

@@ -71,7 +71,7 @@ const char *target_strerror(int err);
 int get_osversion(void);
 void init_qemu_uname_release(void);
 void fork_start(void);
-void fork_end(int child);
+void fork_end(pid_t pid);
 
 /**
  * probe_guest_base: