Created attachment 8015 [details]
proposed patch

Two issues wrt. syscall.epoll_pwait and related testcase:


1) in the syscalls.stp tapset, $events and $sigmask pointers from syscall.epoll_pwait have wrong values on s390 31-on-64. Following update fixes the issue for me and seems to test fine "everywhere".

=======
--- a/tapset/linux/syscalls.stp
+++ b/tapset/linux/syscalls.stp
@@ -857,14 +857,14 @@ probe syscall.epoll_pwait = kernel.function("compat_sys_epoll_pwait").call ?,
 {
        name = "epoll_pwait"
        epfd = __int32($epfd)
-       events_uaddr = $events
+       events_uaddr = @__pointer($events)
        maxevents = __int32($maxevents)
        timeout = __int32($timeout)
-       sigmask_uaddr = $sigmask
+       sigmask_uaddr = @__pointer($sigmask)
        sigsetsize = $sigsetsize
        argstr = sprintf("%d, %p, %d, %d, %p, %d",
-                        __int32($epfd), $events, __int32($maxevents),
-                        __int32($timeout), $sigmask, $sigsetsize)
+                        __int32($epfd), events_uaddr, __int32($maxevents),
+                        __int32($timeout), sigmask_uaddr, $sigsetsize)
 }
=======



2) Second problem is that on el5 x86_64, epoll_pwait() is not available, but SYS_epoll_pwait is defined. This is unlike other el5 arches, where SYS_epoll_pwait is not defined. This causes link time error and skipping the test on the platform in question. Using following wrapper works the issue around for me and seems to test fine "everywhere":

=======
#ifdef SYS_epoll_pwait                                                          
int __epoll_pwait(int epfd, struct epoll_event *events,                         
                  int maxevents, int timeout,                                   
                  const sigset_t *set)                                          
{                                                                               
    return syscall(__NR_epoll_pwait, epfd, events, maxevents, timeout,          
                   set, _NSIG / 8);                                             
}                                                                               
#endif
=======

Related testcases are then being updated like this:

=======
#ifdef SYS_epoll_pwait                                                          
  __epoll_pwait(fd, events, 17, 0, NULL);                                       
  //staptest// [[[[epoll_pwait (NNNN, XXXX, 17, 0, 0x0, NNNN) = 0!!!!ni_syscall () = -38 (ENOSYS)]]]]
                                                                                
  __epoll_pwait(fd, events, 17, 0, &sigs);                                      
  //staptest// [[[[epoll_pwait (NNNN, XXXX, 17, 0, XXXX, NNNN) = 0!!!!ni_syscall () = -38 (ENOSYS)]]]]

... stuff deleted ...

#endif
=======