arch/ppc-sam440/exec/supervisor.c

   1 /*
   2     Copyright © 1995-2012, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Supervisor() - Execute some code in a privileged environment.
   6     Lang: english
   7 */
   8
   9 /*****************************************************************************
  10
  11     NAME */
  12 #include <proto/exec.h>
  13 #include <asm/amcc440.h>
  14
  15         AROS_LH1(ULONG, Supervisor,
  16
  17 /*  SYNOPSIS */
  18         AROS_LHA(ULONG_FUNC, userFunction, A5),
  19
  20 /*  LOCATION */
  21         struct ExecBase *, SysBase, 5, Exec)
  22
  23 /*  FUNCTION
  24         Supervisor will allow a short privileged instruction sequence to
  25         be called from user mode. This has very few uses, and it is probably
  26         better to use any system supplied method to do anything.
  27
  28         The function supplied will be called as if it was a system interrupt,
  29         notably this means that you must *NOT* make any system calls or
  30         use any system data structures, and on certain systems you must
  31         use special methods to leave the code.
  32
  33         The code will not be passed any parameters.
  34
  35     INPUTS
  36         userFunc    -   The address of the code you want called in supervisor
  37                         mode.
  38
  39     RESULT
  40         The code will be called.
  41
  42     NOTES
  43         This function has completely different effects on different
  44         processors and architectures.
  45
  46         Currently defined effects are:
  47
  48         Kernel                      Effect
  49         -------------------------------------------------------------------
  50         i386 (under emulation)      None
  51         m68k (native)               Runs the process in supervisor mode.
  52                                     The process must end with an RTE
  53                                     instruction. It should save any
  54                                     registers which is uses.
  55         m68k (under emulation)
  56
  57     EXAMPLE
  58
  59     BUGS
  60         You can very easily make the system unusable with this function.
  61         In fact it is recommended that you do not use it at all.
  62
  63     SEE ALSO
  64         SuperState(), UserState()
  65
  66     INTERNALS
  67         You can do what you want with this function, even ignoring it if
  68         you don't think it makes any sense. But it could be quite useful
  69         to make it run something under different protection levels.
  70
  71         You should trust that the programmer know what they are doing :-)
  72
  73 ******************************************************************************/
  74 {
  75     AROS_LIBFUNC_INIT
  76
  77     register ULONG retval;
  78     register APTR stack;
  79
  80     stack = SuperState();
  81
  82     retval = (*userFunction)();
  83
  84     UserState(stack);
  85
  86     return retval;
  87
  88     AROS_LIBFUNC_EXIT
  89 } /* Supervisor() */