arch/m68k-all/exec/setfunction.c

   1 /*
   2     Copyright © 1995-2011, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Patch a library or device function
   6     Lang: english
   7 */
   8 #include <aros/config.h>
   9 #include <exec/execbase.h>
  10 #include <proto/intuition.h>
  11 #include <aros/libcall.h>
  12 #include <proto/exec.h>
  13 #include <exec/rawfmt.h>
  14
  15 #include "exec_debug.h"
  16 #include "exec_intern.h"
  17
  18 #ifndef DEBUG_SetFunction
  19 #   define DEBUG_SetFunction 0
  20 #endif
  21 #undef DEBUG
  22 #if DEBUG_SetFunction
  23 #   define DEBUG 1
  24 #endif
  25 #include <aros/debug.h>
  26 #undef kprintf
  27
  28 /* See rom/kernel/setfunction.c for documentation */
  29
  30 /* moveb %d0, %a3@+
  31  * rts
  32  */
  33 const ULONG m68k_string = 0x16c04e75;
  34 /* addql #1, %a3@
  35  * rts
  36  */
  37 const ULONG m68k_count  = 0x52934e75;
  38 /* jmp %a6@(-86 * 6)
  39  */
  40 const ULONG m68k_serial = 0x4eeefdfc;
  41
  42 static AROS_UFH5(APTR, myRawDoFmt,
  43         AROS_UFHA(CONST_STRPTR, fmt, A0),
  44         AROS_UFHA(APTR,        args, A1),
  45         AROS_UFHA(VOID_FUNC,  putch, A2),
  46         AROS_UFHA(APTR,      putptr, A3),
  47         AROS_UFHA(struct ExecBase *, SysBase, A6))
  48 {
  49     AROS_USERFUNC_INIT
  50
  51     switch ((IPTR)putch) {
  52     case (IPTR)RAWFMTFUNC_STRING:
  53         putch = (VOID_FUNC)&m68k_string;
  54         break;
  55     case (IPTR)RAWFMTFUNC_COUNT:
  56         putch = (VOID_FUNC)&m68k_count;
  57         break;
  58     case (IPTR)RAWFMTFUNC_SERIAL:
  59         putch = (VOID_FUNC)&m68k_serial;
  60         break;
  61     default:
  62         break;
  63     }
  64
  65     return AROS_UFC5(APTR, ((struct IntExecBase *)SysBase)->PlatformData.realRawDoFmt,
  66         AROS_UFCA(CONST_STRPTR, fmt, A0),
  67         AROS_UFCA(APTR,        args, A1),
  68         AROS_UFCA(VOID_FUNC,  putch, A2),
  69         AROS_UFCA(APTR,      putptr, A3),
  70         AROS_UFCA(struct ExecBase *, SysBase, A6));
  71
  72     AROS_USERFUNC_EXIT
  73 }
  74
  75 AROS_LH3(APTR, SetFunction,
  76     AROS_LHA(struct Library *, library,     A1),
  77     AROS_LHA(LONG,             funcOffset,  A0),
  78     AROS_LHA(APTR,             newFunction, D0),
  79     struct ExecBase *, SysBase, 70, Exec)
  80 {
  81     AROS_LIBFUNC_INIT
  82     APTR ret;
  83     ULONG *vecaddr;
  84
  85     D(bug("SetFunction(%s, -%lx, %lx) = ", (ULONG)library->lib_Node.ln_Name, -funcOffset, (ULONG)newFunction));
  86
  87     /*
  88         Fix dos.library/ramlib attempts to SetFunction() CloseDevice/
  89         CloseLibrary/RemDevice/RemLibrary/OpenDevice/OpenLibrary.
  90
  91         This also effectively limits the max offset to 32k, but this limit was
  92         already in the original, though not really documented.
  93
  94         What happens is this: the prototype for the funcOffset says it is a
  95         long, but the autodoc also says that only a0.w (lower 16 bits) is used.
  96         Dos.library/ramlib only sets the lower 16 bits of a0 to the required
  97         offset, without sign-extending to the upper 16 bits, in fact without
  98         even clearing them. These high 16 bits will therefore contain garbage:
  99
 100         SetFunction(exec.library, 7804fe3e, fc6524) = 30303030 CloseDevice
 101         SetFunction(exec.library, 3030fe62, fc6528) = 30303030 CloseLibrary
 102         SetFunction(exec.library, 3030fe4a, fc651c) = 30303030 RemDevice
 103         SetFunction(exec.library, 3030fe6e, fc6520) = 30303030 RemLibrary
 104         SetFunction(exec.library, 3030fe44, fc6564) = 30303030 OpenDevice
 105         SetFunction(exec.library, 3030fdd8, fc659a) = 30303030 OpenLibrary
 106
 107         In my [ldp] opinion, the autodoc should never have said that only A0.W
 108         is used for the funcOffset, while specifying a "long" in the prototype.
 109         This will stay broken and this fix will stay here until we fix
 110         dos.library/ramlib.
 111     */
 112     if (funcOffset & 0x00008000)
 113     {
 114         funcOffset |= 0xffff0000;
 115     }
 116     else
 117     {
 118         funcOffset &= 0x0000ffff;
 119     }
 120
 121     /* AOS 3.1's locale.library wants to trample over Exec/RawDoFmt.
 122      * Since the replacement does not understand the 'magic' AROS
 123      * RAWFMTFUNC_xxxx vectors, we need to install a wrapper to
 124      * translate those to real functions.
 125      *
 126      * This should not effect AROS usage of SetFunction() of
 127      * RawDoFmt, as it will only end up adding about 16 m68k
 128      * instructions of overhead.
 129      */
 130     if (library == (APTR)SysBase && funcOffset == (-87 * LIB_VECTSIZE)) {
 131         ((struct IntExecBase *)SysBase)->PlatformData.realRawDoFmt = newFunction;
 132         newFunction = myRawDoFmt;
 133     }
 134
 135     /*
 136         Arbitrate for the jumptable. This isn't enough for interrupt callable
 137         functions - but it need not be.
 138     */
 139     Forbid();
 140
 141     /* Mark the library as changed. */
 142     library->lib_Flags|=LIBF_CHANGED;
 143
 144     /* The following section is coded like this (instead of using the macros),
 145        because else gcc will output 64-bit muls instructions, that are not
 146        present on the 68060 (and will crash it). It's faster this way, too. :) */
 147     vecaddr = (APTR)((ULONG)library + funcOffset);
 148
 149     /* Get the old vector pointer */
 150     ret = (APTR)*(ULONG *)(((ULONG)vecaddr)+2);
 151
 152     /* Set new vector and jmp instruction */
 153     *(UWORD *)vecaddr = 0x4ef9;
 154     *(ULONG *)(((ULONG)vecaddr)+2) = (ULONG)newFunction;
 155
 156 #if 1
 157     CacheClearU();
 158 #else
 159     /* Can't use this because there are broken programs that
 160      * copy code and then call SetFunction().
 161      */
 162     CacheClearE(vecaddr,LIB_VECTSIZE,CACRF_ClearI|CACRF_ClearD);
 163 #endif
 164
 165     /* Arbitration is no longer needed */
 166     Permit();
 167
 168     /* Sum the library up again */
 169     SumLibrary(library);
 170
 171     D(bug("%lx\n", ret));
 172
 173     /* All done. */
 174     return ret;
 175     AROS_LIBFUNC_EXIT
 176 } /* SetFunction */
 177