arch/m68k-amiga/boot/m68k_exception.c

   1 /*
   2     copyright © 1995-2010, the aros development team. all rights reserved.
   3     $id$
   4
   5     desc: m68k-amiga bootstrap to exec.
   6     lang: english
   7  */
   8
   9 #include <aros/kernel.h>
  10 #include <exec/resident.h>
  11 #include <exec/execbase.h>
  12 #include <exec/memory.h>
  13
  14 #include "exec_intern.h"
  15
  16 #include "m68k_exception.h"
  17
  18 /* Here's how it's all laid out on the Amiga
  19  *    M68K Exception
  20  *      0       Reset: Initial SP
  21  *      1       Reset: Initial PC (NOTE: Really is SysBase!)
  22  *      2       Bus Error
  23  *      3       Address Error
  24  *      4       Illegal Instruction
  25  *      5       Divide by Zero
  26  *      6       CHK Instruction
  27  *      7       TRAPV Instruction
  28  *      8       Privileged Instruction
  29  *      9       Trace
  30  *      10      Line 1010 Emulator
  31  *      11      Line 1111 Emulator
  32  *      12      -
  33  *      13      -
  34  *      14      Format Error
  35  *      15      Uninitilaized Interrupt Vector
  36  *      16      -
  37  *      ..
  38  *      23      -
  39  *      24      Spurious Interrupt
  40  *      25      Level 1 Interrupt
  41  *                      Paula 0: Serial TX
  42  *                      Paula 1: Disk DMA done
  43  *                      Paula 2: Software Int
  44  *      26      Level 2 Interrupt
  45  *                      Paula 3: CIA
  46  *      27      Level 3 Interrupt
  47  *                      Paula 4: Copper
  48  *                      Paula 5: Vert Blank
  49  *                      Paula 6: Blitter
  50  *      28      Level 4 Interrupt
  51  *                      Paula 7: Audio 0
  52  *                      Paula 8: Audio 1
  53  *                      Paula 9: Audio 2
  54  *                      Paula 10: Audio 3
  55  *      29      Level 5 Interrupt
  56  *                      Paula 11: Serial RX
  57  *                      Paula 12: Disk Sync
  58  *      30      Level 6 Interrupt
  59  *                      Paula 13: External
  60  *                      Paula 14: Copper (special)
  61  *      31      Level 7 Interrupt
  62  *                      Paula 15: NMI
  63  *      32      TRAP #0
  64  *      ..
  65  *      47      TRAP #15
  66  *      48      -
  67  *      ..
  68  *      63      -
  69  *      64      User 1
  70  *      ..
  71  *      255     User 191
  72  */
  73
  74 /* The stack frame here:
  75  *     Return PC          +(0 + 2 + 4)
  76  *     Return SP          +(0 + 2)
  77  *     Exception struct * +(0)
  78  * SP ->
  79  *
  80  * When we call M68KExceptionAction:
  81  *     D0-D1/A0-A1/A6           (5 * 4) <= NO TOUCHING!
  82  *     SysBase                  (4)     A6
  83  *     SP                       (4)     D1
  84  *     Exception struct *       (4)     D0
  85  *
  86  * When we come back:
  87  *     Drop SysBase, SP, and Exception args
  88  *     Restore D0-D1/A0-A1/A6
  89  *     Drop the Exception # word
  90  *     RTE
  91  */
  92 extern void M68KExceptionHelper(void);
  93 asm (
  94         "       .text\n"
  95         "       .globl M68KExceptionHelper\n"
  96         "M68KExceptionHelper:\n"
  97         "       movem.l %d0-%d1/%a0-%a1/%a6,%sp@-\n"    // What we destory
  98         "       move.l  %sp@(5*4),%d0\n"        // Exception *
  99         "       clr.l   %d1\n"
 100         "       move.w  %sp@(5*4+4),%d1\n"      // SR
 101         "       move.l  4, %a6\n"               // Global SysBase
 102         "       move.l  %a6, %sp@-\n"           // Push SysBase
 103         "       move.l  %d1, %sp@-\n"           // Push SR
 104         "       move.l  %d0, %sp@-\n"           // Push Exception *
 105         "       jsr     M68KExceptionAction\n"
 106         "       lea     %sp@(12),%sp\n"         // Drop all stack args
 107         "       movem.l %sp@+,%d0-%d1/%a0-%a1/%a6\n"    // Restore
 108         "       addq.l  #4, %sp\n"              // Remove Exception *
 109         "       rte\n"                          // And return
 110 );
 111
 112 #undef kprintf
 113
 114 void M68KExceptionAction(struct M68KException *Exception, UWORD SRReg, struct ExecBase *SysBase)
 115 {
 116         if (Exception->Handler == NULL) {
 117                 kprintf("-- Exception %d\n", Exception->Id);
 118                 Alert(AN_BogusExcpt);
 119                 for (;;);
 120         }
 121
 122         Exception->Handler(Exception->Id, SRReg, SysBase);
 123 }
 124
 125 /* We assume that the caller has already set up
 126  * the exceptions to a 'reasonable' default. These
 127  * are only the overrides for AROS.
 128  */
 129 void M68KExceptionInit(const struct M68KException *Table, struct ExecBase *SysBase)
 130 {
 131         IPTR *exception = (IPTR *)0;    /* Exception base is at 0 */
 132         UWORD *jmptab;
 133         int i;
 134         int size;
 135
 136         for (size = 0; Table[size].Id > 0; size++);
 137
 138         /* A little explanation. jmptab will be
 139          * constructed as follows:
 140          *    move.l &Table[i], %sp@+
 141          *      0x2f3c (&Table[i] >> 16) (&Table[i] & 0xffff)
 142          *    jmp %pc@(((size - 1) - i) * (5 * sizeof(UWORD)) + 2)
 143          *      0x4efa (((size - 1) - i) * (5 * sizeof(UWORD)) + 2)
 144          *    ...
 145          *    ...
 146          *    jmp M68KExceptionHelper
 147          *      0x4ef9 (M68KExceptionHelper >> 16) (M68KExceptionHelper & 0xffff)
 148          *
 149          * NOTICE: jmptab will never be freed! */
 150         jmptab = AllocMem(size * (5 * sizeof(UWORD)) + 3 * sizeof(UWORD), 0);
 151
 152         for (i = 0; i < size; i++, jmptab += 5) {
 153                 jmptab[0] = 0x2f3c;     // movel #...,%sp@-
 154                 jmptab[1] = ((IPTR)(&Table[i]) >> 16) & 0xffff;
 155                 jmptab[2] = ((IPTR)(&Table[i]) >>  0) & 0xffff;
 156                 jmptab[3] = 0x4efa;     // jmp %pc@...
 157                 jmptab[4] = ((size - 1) - i) * (5 * sizeof(UWORD)) + 2;
 158                 exception[Table[i].Id] = (IPTR)(&jmptab[0]);
 159         }
 160         jmptab[0] = 0x4ef9;             // jmp ....
 161         jmptab[1] = ((IPTR)(M68KExceptionHelper) >> 16) & 0xffff;
 162         jmptab[2] = ((IPTR)(M68KExceptionHelper) >>  0) & 0xffff;
 163
 164         /* We're all set up now! */
 165 }