1. 24 Jul, 2008 2 commits
    • Roland McGrath's avatar
      x86_64 syscall audit fast-path · 86a1c34a
      Roland McGrath authored
      
      
      This adds a fast path for 64-bit syscall entry and exit when
      TIF_SYSCALL_AUDIT is set, but no other kind of syscall tracing.
      This path does not need to save and restore all registers as
      the general case of tracing does.  Avoiding the iret return path
      when syscall audit is enabled helps performance a lot.
      Signed-off-by: default avatarRoland McGrath <roland@redhat.com>
      86a1c34a
    • Roland McGrath's avatar
      x86_64: remove bogus optimization in sysret_signal · 15e8f348
      Roland McGrath authored
      
      
      This short-circuit path in sysret_signal looks wrong to me.
      AFAICT, in practice the branch is never taken--and if it were,
      it would go wrong.  To wit, try loading a module whose init
      function does set_thread_flag(TIF_IRET), and see insmod crash
      (presumably with a wrong user stack pointer).
      
      This is because the FIXUP_TOP_OF_STACK work hasn't been done yet
      when we jump around the call to ptregscall_common and get to
      int_with_check--where it expects the user RSP,SS,CS and EFLAGS to
      have been stored by FIXUP_TOP_OF_STACK.
      
      I don't think it's normally possible to get to sysret_signal with no
      _TIF_DO_NOTIFY_MASK bits set anyway, so these two instructions are
      already superfluous.  If it ever did happen, it is harmless to call
      do_notify_resume with nothing for it to do.
      Signed-off-by: default avatarRoland McGrath <roland@redhat.com>
      15e8f348
  2. 23 Jul, 2008 38 commits