1. 08 Mar, 2006 1 commit
    • Paul Mackerras's avatar
      powerpc: Fix various syscall/signal/swapcontext bugs · 1bd79336
      Paul Mackerras authored
      A careful reading of the recent changes to the system call entry/exit
      paths revealed several problems, plus some things that could be
      simplified and improved:
      
      * 32-bit wasn't testing the _TIF_NOERROR bit in the syscall fast exit
        path, so it was only doing anything with it once it saw some other
        bit being set.  In other words, the noerror behaviour would apply to
        the next system call where we had to reschedule or deliver a signal,
        which is not necessarily the current system call.
      
      * 32-bit wasn't doing the call to ptrace_notify in the syscall exit
        path when the _TIF_SINGLESTEP bit was set.
      
      * _TIF_RESTOREALL was in both _TIF_USER_WORK_MASK and
        _TIF_PERSYSCALL_MASK, which is odd since _TIF_RESTOREALL is only set
        by system calls.  I took it out of _TIF_USER_WORK_MASK.
      
      * On 64-bit, _TIF_RESTOREALL wasn't causing the non-volatile registers
        to be restored (unless perhaps a signal was delivered or the syscall
        was traced or single-stepped).  Thus the non-volatile registers
        weren't restored on exit from a signal handler.  We probably got
        away with it mostly because signal handlers written in C wouldn't
        alter the non-volatile registers.
      
      * On 32-bit I simplified the code and made it more like 64-bit by
        making the syscall exit path jump to ret_from_except to handle
        preemption and signal delivery.
      
      * 32-bit was calling do_signal unnecessarily when _TIF_RESTOREALL was
        set - but I think because of that 32-bit was actually restoring the
        non-volatile registers on exit from a signal handler.
      
      * I changed the order of enabling interrupts and saving the
        non-volatile registers before calling do_syscall_trace_leave; now we
        enable interrupts first.
      Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
      1bd79336
  2. 03 Mar, 2006 8 commits
  3. 02 Mar, 2006 9 commits
  4. 01 Mar, 2006 22 commits