[PATCH v3] linux-user: Adjust child_tidptr on set_tid_address() syscall

[Helge Deller <deller@gmx.de>]

Keep track of the new child tidptr given by a set_tid_address() syscall.

Do not call the host set_tid_address() syscall because we are emulating
the behaviour of writing to child_tidptr in the exit() path.

Signed-off-by: Helge Deller<deller@gmx.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

--
v3:
- Respin of the patch because the v2 version was mungled in-between the
  mail of the v1 version. Now it's possible to get correct patch with b4
- Rephrased commit message
- Added Richard's Reviewed-by
v2:
- was mungled in v1 mail thread

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index f55cdebee5..1166e9f014 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -320,9 +320,6 @@ _syscall3(int,sys_syslog,int,type,char*,bufp,int,len)
 #ifdef __NR_exit_group
 _syscall1(int,exit_group,int,error_code)
 #endif
-#if defined(TARGET_NR_set_tid_address) && defined(__NR_set_tid_address)
-_syscall1(int,set_tid_address,int *,tidptr)
-#endif
 #if defined(__NR_futex)
 _syscall6(int,sys_futex,int *,uaddr,int,op,int,val,
           const struct timespec *,timeout,int *,uaddr2,int,val3)
@@ -12200,9 +12197,14 @@ static abi_long do_syscall1(CPUArchState *cpu_env, int num, abi_long arg1,
     }
 #endif

-#if defined(TARGET_NR_set_tid_address) && defined(__NR_set_tid_address)
+#if defined(TARGET_NR_set_tid_address)
     case TARGET_NR_set_tid_address:
-        return get_errno(set_tid_address((int *)g2h(cpu, arg1)));
+    {
+        TaskState *ts = cpu->opaque;
+        ts->child_tidptr = arg1;
+        /* do not call host set_tid_address() syscall, instead return tid() */
+        return get_errno(sys_gettid());
+    }
 #endif

     case TARGET_NR_tkill: