I think the previous patch was wrong, since we just emulate writing to child_tidptr. Below is updated RFC patch.
--- [PATCH] linux-user: Adjust child_tidptr on set_tid_address() Keep track of the new child tidptr given by a set_tid_address() syscall. Signed-off-by: Helge Deller <del...@gmx.de> diff --git a/linux-user/syscall.c b/linux-user/syscall.c index f65045efe6..9114c611a0 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(void *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: