rom/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 #include <exec/alerts.h>
  10
  11 #include "exec_util.h"
  12
  13 /*****************************************************************************
  14
  15     NAME */
  16 #include <proto/exec.h>
  17
  18         AROS_LH1(IPTR, Supervisor,
  19
  20 /*  SYNOPSIS */
  21         AROS_LHA(void *, userFunction, A5),
  22
  23 /*  LOCATION */
  24         struct ExecBase *, SysBase, 5, Exec)
  25
  26 /*  FUNCTION
  27         Supervisor will allow a short privileged instruction sequence to
  28         be called from user mode. This has very few uses, and it is probably
  29         better to use any system supplied method to do anything.
  30
  31         The function supplied will be called as if it was a system interrupt,
  32         notably this means that you must *NOT* make any system calls or
  33         use any system data structures, and on certain systems you must
  34         use special methods to leave the code.
  35
  36         The code will not be passed any parameters. However it has access to all
  37         CPU registers.
  38
  39     INPUTS
  40         userFunction -  The address of the code you want called in supervisor
  41                         mode.
  42
  43     RESULT
  44         The code will be called.
  45
  46     NOTES
  47         On some architectures this function is impossible or infeasible to implement.
  48         In this case it throws a recoverable alert.
  49
  50         Currently this function works only on x86 and PowerPC native kickstarts.
  51
  52     EXAMPLE
  53
  54     BUGS
  55         You can very easily make the system unusable with this function.
  56         In fact it is recommended that you do not use it at all.
  57
  58     SEE ALSO
  59         SuperState(), UserState()
  60
  61     INTERNALS
  62         You can do what you want with this function, even ignoring it if
  63         you don't think it makes any sense. But it could be quite useful
  64         to make it run something under different protection levels.
  65
  66         You should trust that the programmer know what they are doing :-)
  67
  68 ******************************************************************************/
  69 {
  70     AROS_LIBFUNC_INIT
  71
  72     /*
  73      * This fallback implementation throws a recovertable alert and
  74      * returns dummy value. Since we should actually call a real interrupt,
  75      * there's no generic way to simulate this.
  76      * See architecture-specific code for working implementations.
  77      */
  78     Exec_ExtAlert(ACPU_PrivErr & ~AT_DeadEnd, __builtin_return_address(0), CALLER_FRAME, 0, NULL, SysBase);
  79     return 0;
  80
  81     AROS_LIBFUNC_EXIT
  82 } /* Supervisor() */