Re: [RFC] mask off is-syscall bit for TRAP_IS_SYSCALL

[Pedro Alves <pedro at codesourcery dot com>]

On Monday 28 September 2009 20:39:05, Doug Evans wrote:
> Hi.
> 
> On one system I use (bi-arch ubuntu-hardy clone),
> i386-disp-step.exp is failing because the wait status
> value linux_nat_wait_1 gets when hitting a system call is 0857f
> which gets passed to the upper layers which then get confused
> by a signal of 0x85 (== 0x80 | SIGTRAP).
> 
> This patch fixes things by masking off the 0x80 bit before
> passing the signal number to up the call chain.
> 
> Ok to check in?

This seems OK-is to me, although I see one extra case that
isn't handled correctly:

stop_wait_callback:

      status = wait_lwp (lp);

...

      if (WSTOPSIG (status) != SIGSTOP)
	{
	  if (WSTOPSIG (status) == SIGTRAP)
	    {
...
            }
          else
            {
	      /* If the lp->status field is still empty, use it to
		 hold this event.  If not, then this event must be
		 returned to the event queue of the LWP.  */
	      if (lp->status)
		{
		  if (debug_linux_nat)
		    {
		      fprintf_unfiltered (gdb_stdlog,
					  "SWC: kill %s, %s\n",
					  target_pid_to_str (lp->ptid),
					  status_to_str ((int) status));
		    }
		  kill_lwp (GET_LWP (lp->ptid), WSTOPSIG (status));      <<<<<<<<
		}

It seems we can reach that <<< marked code with a TRAP_IS_SYSCALL, but,
I doubt that we want to requeue that signal in the kernel (?).

-- 
Pedro Alves