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  1. 11 May, 2008 2 commits
    • David S. Miller's avatar
      sparc: Fix debugger syscall restart interactions. · 28e61036
      David S. Miller authored 
      So, forever, we've had this ptrace_signal_deliver implementation
which tries to handle all of the nasties that can occur when the
debugger looks at a process about to take a signal.  It's meant
to address all of these issues inside of the kernel so that the
debugger need not be mindful of such things.

Problem is, this doesn't work.

The idea was that we should do the syscall restart business first, so
that the debugger captures that state.  Otherwise, if the debugger for
example saves the child's state, makes the child execute something
else, then restores the saved state, we won't handle the syscall
restart properly because we lose the "we're in a syscall" state.

The code here worked for most cases, but if the debugger actually
passes the signal through to the child unaltered, it's possible that
we would do a syscall restart when we shouldn't have.

In particular this breaks the case of debugging a process under a gdb
which is being debugged by yet another gdb.  gdb uses sigsuspend
to wait for SIGCHLD of the inferior, but if gdb itself is being
debugged by a top-level gdb we get a ptrace_stop().  The top-level gdb
does a PTRACE_CONT with SIGCHLD to let the inferior gdb see the
signal.  But ptrace_signal_deliver() assumed the debugger would cancel
out the signal and therefore did a syscall restart, because the return
error was ERESTARTNOHAND.

Fix this by simply making ptrace_signal_deliver() a nop, and providing
a way for the debugger to control system call restarting properly:

1) Report a "in syscall" software bit in regs->{tstate,psr}.
   It is set early on in trap entry to a system call and is fully
   visible to the debugger via ptrace() and regsets.

2) Test this bit right before doing a syscall restart.  We have
   to do a final recheck right after get_signal_to_deliver() in
   case the debugger cleared the bit during ptrace_stop().

3) Clear the bit in trap return so we don't accidently try to set
   that bit in the real register.

As a result we also get a ptrace_{is,clear}_syscall() for sparc32 just
like sparc64 has.

M68K has this same exact bug, and is now the only other user of the
ptrace_signal_deliver hook.  It needs to be fixed in the same exact
way as sparc.
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      28e61036
    • David S. Miller's avatar
      sparc: Fix ptrace() detach. · 986bef85
      David S. Miller authored 
      Forever we had a PTRACE_SUNOS_DETACH which was unconditionally
recognized, regardless of the personality of the process.

Unfortunately, this value is what ended up in the GLIBC sys/ptrace.h
header file on sparc as PTRACE_DETACH and PT_DETACH.

So continue to recognize this old value.  Luckily, it doesn't conflict
with anything we actually care about.
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      986bef85
  3. 10 May, 2008 1 commit
  5. 09 May, 2008 1 commit
  7. 08 May, 2008 1 commit
    • David S. Miller's avatar
      sparc: Fix SA_ONSTACK signal handling. · dc5dc7e6
      David S. Miller authored 
      We need to be more liberal about the alignment of the buffer given to
us by sigaltstack().  The user should not need to be mindful of all of
the alignment constraints we have for the stack frame.

This mirrors how we handle this situation in clone() as well.

Also, we align the stack even in non-SA_ONSTACK cases so that signals
due to bad stack alignment can be delivered properly.  This makes such
errors easier to debug and recover from.

Finally, add the sanity check x86 has to make sure we won't overflow
the signal stack.

This fixes glibc testcases nptl/tst-cancel20.c and
nptl/tst-cancelx20.c
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      dc5dc7e6
  9. 07 May, 2008 2 commits
  11. 06 May, 2008 2 commits
  13. 05 May, 2008 3 commits
  15. 04 May, 2008 3 commits
  17. 03 May, 2008 17 commits
  19. 02 May, 2008 8 commits