1| $NetBSD: SRT0.S,v 1.4 2009/10/21 23:12:09 snj Exp $ 2 3| Copyright (c) 1995 Gordon W. Ross 4| All rights reserved. 5| 6| Redistribution and use in source and binary forms, with or without 7| modification, are permitted provided that the following conditions 8| are met: 9| 1. Redistributions of source code must retain the above copyright 10| notice, this list of conditions and the following disclaimer. 11| 2. Redistributions in binary form must reproduce the above copyright 12| notice, this list of conditions and the following disclaimer in the 13| documentation and/or other materials provided with the distribution. 14| 15| THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16| IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17| OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18| IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19| INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20| NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21| DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22| THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23| (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24| THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 26| this is a pre-startup wrapper for bugcrt which relocates the 27| code to the correct place before exec()ing. 28 29| SRT0.S - Stand-alone Run-Time startup code, part 0 30 31#include <m68k/asm.h> 32 33 .file "SRT0.S" 34 .text 35GLOBAL(_estack) 36 37xstart: 38| first, relocate code to correct place without touching critical regs 39| (args are in: d0, d1, d4, a0, a1, a2, a3, a4, a5, a6) 40| [a3 and a4 only when netbooting] 41 movl %a3, %d3 | SAVE a3 in d3 42 movl %a4, %d5 | SAVE a4 in d5 43 lea %pc@(xstart:w), %a3 | a3 = current addr (could be anywhere) 44 lea xstart:l, %a4 | a4 = desired location (LINKADDR) 45 cmpl %a3, %a4 | already there? 46 beqs restart | short-circuit out 47 48 | Relocate the code and data 49 movl #_C_LABEL(edata),%d2 | Desired end of program 50 subl %a4,%d2 | Calculate length, round up. 51 lsrl #2,%d2 52Lcp: 53 movl %a3@+, %a4@+ 54 dbra %d2, Lcp 55 56| Force a long jump to the relocated code (not pc-relative) 57 lea restart:l, %a3 58 jmp %a3@ 59 60restart: 61| now in the relocated code 62 63| Set up stack (just before relocated text) 64 lea _C_LABEL(_estack):l, %a3 65 movl %a3, %sp 66 67| now that we have relocated, call the bugcrt (note we skip over the special 68| bug header which has a PC and SP in it) 69 movl %d3, %a3 | RESTORE a3 70 movl %d5, %a4 | RESTORE a4 71 jmp _start 72 73| The end. 74