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  1. 11 May, 2008 1 commit
    • 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
  2. 19 Jan, 2006 1 commit
  3. 16 Apr, 2005 1 commit
    • Linus Torvalds's avatar
      Linux-2.6.12-rc2 · 1da177e4
      Linus Torvalds authored
      Initial git repository build. I'm not bothering with the full history,
      even though we have it. We can create a separate "historical" git
      archive of that later if we want to, and in the meantime it's about
      3.2GB when imported into git - space that would just make the early
      git days unnecessarily complicated, when we don't have a lot of good
      infrastructure for it.
      
      Let it rip!
      1da177e4