arch/.unmaintained/arm-all/exec/preparecontext.c

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4 */
   5
   6 #include <exec/types.h>
   7 #include <aros/libcall.h>
   8 #include <exec/execbase.h>
   9 #include <exec/tasks.h>
  10 #include <exec/memory.h>
  11 #include <exec/ptrace.h>
  12 #include "etask.h"
  13 #include "exec_util.h"
  14
  15 #define DEBUG 1
  16 #include <aros/debug.h>
  17
  18 #error "PrepareContext() has been changed. Additional tagList param, etc."
  19 #error "This one here needs to be rewritten!"
  20
  21 /*****************************************************************************
  22
  23     NAME */
  24
  25         AROS_LH3(BOOL, PrepareContext,
  26
  27 /*  SYNOPSIS */
  28         AROS_LHA(struct Task *, task, A0),
  29         AROS_LHA(APTR, entryPoint,   A1),
  30         AROS_LHA(APTR, fallBack,     A2),
  31
  32 /*  LOCATION */
  33         struct ExecBase *, SysBase, 6, Exec)
  34
  35 /*  FUNCTION
  36         Allocates the space required to hold a new set of registers on the
  37         Stack given by stackPointer and clears the area except for pc which
  38         is set to the address given by entryPoint.
  39
  40     INPUTS
  41         task         - Pointer to the new task
  42         entryPoint   - Address of the function to call when the new context
  43                        becomes active.
  44         fallBack     - Address to be called when the entryPoint function ended
  45                        with an rts.
  46
  47     RESULT
  48         The new Stackpointer with the underlying context.
  49
  50     NOTES
  51         This function is for internal use by exec only.
  52
  53         This function is processor dependant.
  54
  55     EXAMPLE
  56
  57     BUGS
  58
  59     SEE ALSO
  60         SwitchTasks()
  61
  62     INTERNALS
  63
  64     HISTORY
  65
  66 ******************************************************************************/
  67 {
  68         AROS_LIBFUNC_INIT
  69
  70         struct pt_regs *regs;
  71
  72         ULONG *sp = (ULONG *)task->tc_SPReg;
  73         ULONG * armregs;
  74         ULONG i = 0;
  75
  76         if (!(task->tc_Flags & TF_ETASK)) {
  77                 return FALSE;
  78         }
  79
  80         GetIntETask (task)->iet_Context = AllocTaskMem (task
  81             , SIZEOF_ALL_REGISTERS
  82             , MEMF_PUBLIC|MEMF_CLEAR
  83         );
  84
  85         if (!(regs  = (struct pt_regs *)GetIntETask(task)->iet_Context)) {
  86                 return FALSE;
  87         }
  88
  89         /*
  90          * Fill the registers r0-r3 with the arguments on the stack -
  91          * if there are any...
  92          */
  93         armregs = &regs->r0;
  94 #if 0
  95         D(bug("sp=%x, task->tc_SPUpper=%x, name=%s\n",
  96               sp,
  97               task->tc_SPUpper,
  98               task->tc_Node.ln_Name));
  99 #endif
 100         if (sp < (ULONG *)task->tc_SPUpper) {
 101                 while (sp < (ULONG *)task->tc_SPUpper && i < 4) {
 102 //                      D(bug("before: armregs=%x, sp=%x\n",armregs,sp));
 103                         *armregs = *sp;
 104                         armregs++;
 105                         sp++;
 106                         i++;
 107 //                      D(bug("after: armregs=%x, sp=%x\n",armregs,sp));
 108                 }
 109                 sp--;
 110         }
 111
 112         /*
 113          * Initialize initial registers. Only sp and lr_svc
 114          * are important. lr_svc represents the entry point of
 115          * the process plus 4. The 4 will be subtracted automatically
 116          * when the process is started. It must be done that way
 117          * due to how the ARM processor works when handling *interrupts*!
 118          * Also set the processor for User Mode.
 119          */
 120         regs->sp      = sp;
 121         regs->lr_svc  = (ULONG)entryPoint+4;
 122         regs->cpsr    = (ULONG)0x10;
 123
 124         /*
 125          * Now I am not sure whether this is going to work.
 126          * In the *startup* code I will need to make sure
 127          * that the fallback can be executed!
 128          * Note that no '4' needs to be added in this case!
 129          */
 130         regs->lr      = (ULONG)fallBack;
 131
 132         return TRUE;
 133         AROS_LIBFUNC_EXIT
 134 }