| $NetBSD: SRT0.S,v 1.2 2008/05/04 00:18:16 martin Exp $
| Copyright (c) 1998 The NetBSD Foundation, Inc.
| All rights reserved.
|
| This code is derived from software contributed to The NetBSD Foundation
| by Gordon W. Ross.
|
| Redistribution and use in source and binary forms, with or without
| modification, are permitted provided that the following conditions
| are met:
| 1. Redistributions of source code must retain the above copyright
| notice, this list of conditions and the following disclaimer.
| 2. Redistributions in binary form must reproduce the above copyright
| notice, this list of conditions and the following disclaimer in the
| documentation and/or other materials provided with the distribution.
|
| THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
| ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
| TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
| PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
| BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
| CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
| SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
| INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
| CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
| ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
| POSSIBILITY OF SUCH DAMAGE.
| Flush the CPU cache using MC68020 values just to be safe.
| This will cause the MC68030 to run with the data cache
| disabled, but that is OK for boot programs.
.set IC_CLEAR,0x9
.set PSL_HIGHIPL,0x2700
.text
ASENTRY_NOPROFILE(start)
| Disable interrupts (just in case...)
movw #PSL_HIGHIPL,%sr
| Check to see if the code is located correctly.
| Get current location via PC-relative load, then...
lea %pc@(start:w),%a0 | current location (0x4000)
| ...force a long (not PC-relative) load to a1 and compare.
lea start:l,%a1 | desired location (LINKADDR)
cmpl %a0,%a1
beqs restart
| Relocate the code and data to where they belong.
movl #_edata,%d0 | Desired end of program
subl %a1,%d0 | Calculate length, round up.
lsrl #2,%d0
Lcp:
movl %a0@+,%a1@+
dbra %d0,Lcp
| If we are on a sun2, we don't want to clear the I-cache
| because we don't have one. We are on a sun2 if the PROM
| has pointed the vector base register to zero. This is
| similar to the test that SRT1.c's _start does.
movc %vbr, %d0
tstl %d0
beqs Ljmpreloc
| Clear the I-cache in case the copied code was cached.
movl #IC_CLEAR,%d0
movc %d0,%cacr
Ljmpreloc:
| Force a long jump to the relocated code (not pc-relative)
lea restart:l,%a0
jmp %a0@
| Define the location of our stack (just before relocated text).
| Leave room the exit jmpbuf at the end of our stack.
.set estack,start-60
restart:
| Now in the relocated code, using the monitor stack.
| Save this context so we can return with it.
pea estack
jsr _C_LABEL(setjmp)
addqw #4,%sp
tstl %d0
bne Ldone | here via longjmp
| Switch to our own stack.
lea estack,%a0
movl %a0,%sp
subl %a6,%a6
| Clear out BSS...
lea _edata,%a0
lea _end,%a1
Lclrbss:
clrl %a0@+
cmpl %a1,%a0
ble Lclrbss
| Call the run-time startup C code, which will:
| initialize, call main, call exit.
jsr _C_LABEL(_start)
| Switch back to the monitor stack, then either
| "chain" to the next program or return.
ENTRY(exit)
pea estack
jsr _C_LABEL(longjmp) | to next line
Ldone:
movl _C_LABEL(chain_to_func),%a0
movl %a0,%d0
beq Lret
jmp %a0@
Lret:
rts
| function to clear the I-cache
ENTRY(ICIA)
tstl _C_LABEL(_is2)
bne Lret
movl #IC_CLEAR,%d0
movc %d0,%cacr
rts
| function to get the vector base register
ENTRY(getvbr)
movc %vbr,%a0
rts
| Kernel version of setjmp/longjmp (label_t is 16 words)
