path: root/sys/arch/sun3/sun3/locore.s

/*	$OpenBSD: locore.s,v 1.21 2000/11/09 01:27:38 miod Exp $	*/
/*	$NetBSD: locore.s,v 1.40 1996/11/06 20:19:54 cgd Exp $	*/

/*
 * Copyright (c) 1994, 1995 Gordon W. Ross
 * Copyright (c) 1993 Adam Glass
 * Copyright (c) 1988 University of Utah.
 * Copyright (c) 1980, 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the Systems Programming Group of the University of Utah Computer
 * Science Department.
 *
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 *
 *	from: Utah $Hdr: locore.s 1.66 92/12/22$
 *	@(#)locore.s	8.6 (Berkeley) 5/27/94
 */

#include "assym.h"
#include <machine/asm.h>
#include <machine/trap.h>

| Remember this is a fun project!

| This is for kvm_mkdb, and should be the address of the beginning
| of the kernel text segment (not necessarily the same as kernbase).
	.text
GLOBAL(kernel_text)

| This is the entry point, as well as the end of the temporary stack
| used during process switch (one 8K page ending at start)
ASGLOBAL(tmpstk)
ASGLOBAL(start)

| First we need to set it up so we can access the sun MMU, and be otherwise
| undisturbed.  Until otherwise noted, all code must be position independent
| as the boot loader put us low in memory, but we are linked high.
	movw	#PSL_HIGHIPL, sr	| no interrupts
	moveq	#FC_CONTROL, d0		| make movs access "control"
	movc	d0, sfc			| space where the sun3 designers
	movc	d0, dfc			| put all the "useful" stuff

| Set context zero and stay there until pmap_bootstrap.
	moveq	#0, d0
	movsb	d0, CONTEXT_REG

| In order to "move" the kernel to high memory, we are going to copy the
| first 4 Mb of pmegs such that we will be mapped at the linked address.
| This is all done by copying in the segment map (top-level MMU table).
| We will unscramble which PMEGs we actually need later.

	movl	#(SEGMAP_BASE+0), a0		| src
	movl	#(SEGMAP_BASE+KERNBASE), a1	| dst
	movl	#(0x400000/NBSG), d0		| count

L_per_pmeg:
	movsb	a0@, d1			| copy segmap entry
	movsb	d1, a1@
	addl	#NBSG, a0		| increment pointers
	addl	#NBSG, a1
	subql	#1, d0			| decrement count
	bgt	L_per_pmeg

| Kernel is now double mapped at zero and KERNBASE.
| Force a long jump to the relocated code (high VA).
	movl	#IC_CLEAR, d0		| Flush the I-cache
	movc	d0, cacr
	jmp L_high_code:l		| long jump

L_high_code:
| We are now running in the correctly relocated kernel, so
| we are no longer restricted to position-independent code.

| Do bootstrap stuff needed before main() gets called.
| Our boot loader leaves a copy of the kernel's exec header
| just before the start of the kernel text segment, so the
| kernel can sanity-check the DDB symbols at [end...esym].
| Pass the struct exec at tmpstk-32 to sun3_bootstrap().
| Also, make sure the initial frame pointer is zero so that
| the backtrace algorithm used by KGDB terminates nicely.
	lea	_ASM_LABEL(tmpstk)-32, sp
	movl	#0, a6
	jsr	_C_LABEL(sun3_bootstrap)

| Now that sun3_bootstrap() is done using the PROM functions,
| we can safely set the sfc/dfc to something != FC_CONTROL
	moveq	#FC_USERD, d0		| make movs access "user data"
	movc	d0, sfc			| space for copyin/copyout
	movc	d0, dfc

| Setup process zero user/kernel stacks.
	movl	_C_LABEL(proc0paddr),a1	| get proc0 pcb addr
	lea	a1@(USPACE-4),sp	| set SSP to last word
	movl	#USRSTACK-4,a2
	movl	a2,usp			| init user SP

| Note curpcb was already set in sun3_bootstrap().
| Will do fpu initialization during autoconfig (see fpu.c)
| The interrupt vector table and stack are now ready.
| Interrupts will be enabled later, AFTER autoconfiguration
| is finished, to avoid spurious interrupts.

/*
 * Final preparation for calling main.
 *
 * Create a fake exception frame that returns to user mode,
 * and save its address in p->p_md.md_regs for cpu_fork().
 * The new frames for process 1 and 2 will be adjusted by
 * cpu_set_kpc() to arrange for a call to a kernel function
 * before the new process does its rte out to user mode.
 */
  	clrw	sp@-			| vector offset/frame type
	clrl	sp@-			| PC - filled in by "execve"
  	movw	#PSL_USER,sp@-		| in user mode
	clrl	sp@-			| stack adjust count and padding
	lea	sp@(-64),sp		| construct space for D0-D7/A0-A7
	movl	sp,a1			| a1=trapframe
	lea	_C_LABEL(proc0),a0	| proc0 in a0
	movl	a1,a0@(P_MDREGS)	| save frame for proc0
	movl	a2,a1@(FR_SP)		| a2 == usp (from above)
	pea	a1@			| push &trapframe
	jbsr	_C_LABEL(main)		| main(&trapframe)
	addql	#4,sp			| help DDB backtrace
	trap	#15			| should not get here

| This is used by cpu_fork() to return to user mode.
| It is called with SP pointing to a struct trapframe.
GLOBAL(proc_do_uret)
	movl	sp@(FR_SP),a0		| grab and load
	movl	a0,usp			|   user SP
	moveml	sp@+,#0x7FFF		| load most registers (all but SSP)
	addql	#8,sp			| pop SSP and stack adjust count
  	rte

/*
 * proc_trampoline:
 * This is used by cpu_set_kpc() to "push" a function call onto the
 * kernel stack of some process, very much like a signal delivery.
 * When we get here, the stack has:
 *
 * SP+8:	switchframe from before cpu_set_kpc
 * SP+4:	void *proc;
 * SP:  	u_long func;
 *
 * On entry, the switchframe pushed by cpu_set_kpc has already been
 * popped off the stack, so all this needs to do is pop the function
 * pointer into a register, call it, then pop the arg, and finally
 * return using the switchframe that remains on the stack.
 */
GLOBAL(proc_trampoline)
	movl	sp@+,a0			| function pointer
	jbsr	a0@			| (*func)(procp)
	addql	#4,sp			| toss the arg
	rts				| as cpu_switch would do

| That is all the assembly startup code we need on the sun3!
| The rest of this is like the hp300/locore.s where possible.

/*
 * Trap/interrupt vector routines
 */
#include <m68k/m68k/trap_subr.s>

GLOBAL(buserr)
	tstl	_C_LABEL(nofault)	| device probe?
	jeq	_C_LABEL(addrerr)	| no, handle as usual
	movl	_C_LABEL(nofault),sp@-	| yes,
	jbsr	_C_LABEL(longjmp)	|  longjmp(nofault)
GLOBAL(addrerr)
	clrl	sp@-			| stack adjust count
	moveml	#0xFFFF,sp@-		| save user registers
	movl	usp,a0			| save the user SP
	movl	a0,sp@(FR_SP)		|   in the savearea
	lea	sp@(FR_HW),a1		| grab base of HW berr frame
	moveq	#0,d0
	movw	a1@(10),d0		| grab SSW for fault processing
	btst	#12,d0			| RB set?
	jeq	LbeX0			| no, test RC
	bset	#14,d0			| yes, must set FB
	movw	d0,a1@(10)		| for hardware too
LbeX0:
	btst	#13,d0			| RC set?
	jeq	LbeX1			| no, skip
	bset	#15,d0			| yes, must set FC
	movw	d0,a1@(10)		| for hardware too
LbeX1:
	btst	#8,d0			| data fault?
	jeq	Lbe0			| no, check for hard cases
	movl	a1@(16),d1		| fault address is as given in frame
	jra	Lbe10			| thats it
Lbe0:
	btst	#4,a1@(6)		| long (type B) stack frame?
	jne	Lbe4			| yes, go handle
	movl	a1@(2),d1		| no, can use save PC
	btst	#14,d0			| FB set?
	jeq	Lbe3			| no, try FC
	addql	#4,d1			| yes, adjust address
	jra	Lbe10			| done
Lbe3:
	btst	#15,d0			| FC set?
	jeq	Lbe10			| no, done
	addql	#2,d1			| yes, adjust address
	jra	Lbe10			| done
Lbe4:
	movl	a1@(36),d1		| long format, use stage B address
	btst	#15,d0			| FC set?
	jeq	Lbe10			| no, all done
	subql	#2,d1			| yes, adjust address
Lbe10:
	movl	d1,sp@-			| push fault VA
	movl	d0,sp@-			| and padded SSW
	movw	a1@(6),d0		| get frame format/vector offset
	andw	#0x0FFF,d0		| clear out frame format
	cmpw	#12,d0			| address error vector?
	jeq	Lisaerr			| yes, go to it

/*
 * the sun3 specific code
 *
 * our mission: figure out whether what we are looking at is
 *              bus error in the UNIX sense, or
 *	        a memory error i.e a page fault
 *
 * [this code replaces similarly mmu specific code in the hp300 code]
 */
sun3_mmu_specific:
	clrl d0				| make sure top bits are cleard too
	movl d1, sp@-			| save d1
	movc sfc, d1			| save sfc to d1
	moveq #FC_CONTROL, d0		| sfc = FC_CONTROL
	movc d0, sfc
	movsb BUSERR_REG, d0		| get value of bus error register
	movc d1, sfc			| restore sfc
	movl sp@+, d1			| restore d1
	andb #BUSERR_MMU, d0 		| is this an MMU fault?
	jeq Lisberr			| non-MMU bus error
/* End of sun3 specific code. */

Lismerr:
	movl	#T_MMUFLT,sp@-		| show that we are an MMU fault
	jra	_ASM_LABEL(faultstkadj)	| and deal with it
Lisaerr:
	movl	#T_ADDRERR,sp@-		| mark address error
	jra	_ASM_LABEL(faultstkadj)	| and deal with it
Lisberr:
	movl	#T_BUSERR,sp@-		| mark bus error
	jra	_ASM_LABEL(faultstkadj)	| and deal with it

/*
 * FP exceptions.
 */
GLOBAL(fpfline)
	clrl	sp@-			| stack adjust count
	moveml	#0xFFFF,sp@-		| save registers
	moveq	#T_FPEMULI,d0		| denote as FP emulation trap
	jra	_ASM_LABEL(fault)	| do it

GLOBAL(fpunsupp)
	clrl	sp@-			| stack adjust count
	moveml	#0xFFFF,sp@-		| save registers
	moveq	#T_FPEMULD,d0		| denote as FP emulation trap
	jra	_ASM_LABEL(fault)	| do it

/*
 * Handles all other FP coprocessor exceptions.
 * Note that since some FP exceptions generate mid-instruction frames
 * and may cause signal delivery, we need to test for stack adjustment
 * after the trap call.
 */
GLOBAL(fpfault)
	clrl	sp@-		| stack adjust count
	moveml	#0xFFFF,sp@-	| save user registers
	movl	usp,a0		| and save
	movl	a0,sp@(FR_SP)	|   the user stack pointer
	clrl	sp@-		| no VA arg
	movl	_C_LABEL(curpcb),a0	| current pcb
	lea	a0@(PCB_FPCTX),a0 | address of FP savearea
	fsave	a0@		| save state
	tstb	a0@		| null state frame?
	jeq	Lfptnull	| yes, safe
	clrw	d0		| no, need to tweak BIU
	movb	a0@(1),d0	| get frame size
	bset	#3,a0@(0,d0:w)	| set exc_pend bit of BIU
Lfptnull:
	fmovem	fpsr,sp@-	| push fpsr as code argument
	frestore a0@		| restore state
	movl	#T_FPERR,sp@-	| push type arg
	jra	_ASM_LABEL(faultstkadj)	| call trap and deal with stack cleanup

	.globl	_straytrap
/*
 * Other exceptions only cause four and six word stack frame and require
 * no post-trap stack adjustment.
 */
GLOBAL(badtrap)
	clrl	sp@-			| stack adjust count
	moveml	#0xFFFF,sp@-		| save std frame regs
	jbsr	_C_LABEL(straytrap)	| report
	moveml	sp@+,#0xFFFF		| restore regs
	addql	#4, sp			| stack adjust count
	jra	_ASM_LABEL(rei)		| all done

/*
 * Trap 0 is for system calls
 */
	.globl	_syscall
GLOBAL(trap0)
	clrl	sp@-			| stack adjust count
	moveml	#0xFFFF,sp@-		| save user registers
	movl	usp,a0			| save the user SP
	movl	a0,sp@(FR_SP)		|   in the savearea
	movl	d0,sp@-			| push syscall number
	jbsr	_C_LABEL(syscall)	| handle it
	addql	#4,sp			| pop syscall arg
	movl	sp@(FR_SP),a0		| grab and restore
	movl	a0,usp			|   user SP
	moveml	sp@+,#0x7FFF		| restore most registers
	addql	#8,sp			| pop SP and stack adjust
	jra	_ASM_LABEL(rei)		| all done

/* Use common m68k sigreturn */
#include <m68k/m68k/sigreturn.s>
	
/*
 * Trace (single-step) trap.  Kernel-mode is special.
 * User mode traps are simply passed on to trap().
 */
GLOBAL(trace)
	clrl	sp@-			| stack adjust count
	moveml	#0xFFFF,sp@-
	moveq	#T_TRACE,d0
	btst	#5,sp@(FR_HW)		| was system mode?
	jne	_ASM_LABEL(kbrkpt)	| yes, kernel breakpoint
	jra	_ASM_LABEL(fault)	| no, user-mode fault

/*
 * Trap 15 is used for:
 *	- GDB breakpoints (in user programs)
 *	- KGDB breakpoints (in the kernel)
 *	- trace traps for SUN binaries (not fully supported yet)
 * User mode traps are simply passed to trap()
 */
GLOBAL(trap15)
	clrl	sp@-			| stack adjust count
	moveml	#0xFFFF,sp@-
	moveq	#T_TRAP15,d0
	btst	#5,sp@(FR_HW)		| was system mode?
	jne	_ASM_LABEL(kbrkpt)	| yes, kernel breakpoint
	jra	_ASM_LABEL(fault)	| no, user-mode fault

ASLOCAL(kbrkpt)
	| Kernel-mode breakpoint or trace trap. (d0=trap_type)
	| Save the system sp rather than the user sp.
	movw	#PSL_HIGHIPL,sr		| lock out interrupts
	lea	sp@(FR_SIZE),a6		| Save stack pointer
	movl	a6,sp@(FR_SP)		|  from before trap

	| If we are not on tmpstk switch to it.
	| (so debugger can change the stack pointer)
	movl	a6,d1
	cmpl	#_ASM_LABEL(tmpstk),d1
	jls	Lbrkpt2 		| already on tmpstk
	| Copy frame to the temporary stack
	movl	sp,a0			| a0=src
	lea	_ASM_LABEL(tmpstk)-96,a1	| a1=dst
	movl	a1,sp			| sp=new frame
	moveq	#FR_SIZE,d1
Lbrkpt1:
	movl	a0@+,a1@+
	subql	#4,d1
	bgt	Lbrkpt1

Lbrkpt2:
	| Call the trap handler for the kernel debugger.
	| Do not call trap() to handle it, so that we can
	| set breakpoints in trap() if we want.  We know
	| the trap type is either T_TRACE or T_BREAKPOINT.
	| If we have both DDB and KGDB, let KGDB see it first,
	| because KGDB will just return 0 if not connected.
	| Save args in d2, a2
	movl	d0,d2			| trap type
	movl	sp,a2			| frame ptr
#ifdef	KGDB
	| Let KGDB handle it (if connected)
	movl	a2,sp@-			| push frame ptr
	movl	d2,sp@-			| push trap type
	jbsr	_C_LABEL(kgdb_trap)	| handle the trap
	addql	#8,sp			| pop args
	cmpl	#0,d0			| did kgdb handle it
	jne	Lbrkpt3			| yes, done
#endif
#ifdef	DDB
	| Let DDB handle it.
	movl	a2,sp@-			| push frame ptr
	movl	d2,sp@-			| push trap type
	jbsr	_C_LABEL(kdb_trap)	| handle the trap
	addql	#8,sp			| pop args
	cmpl	#0,d0			| did ddb handle it
	jne	Lbrkpt3			| yes, done
#endif
	| Drop into the PROM temporarily...
	movl	a2,sp@-			| push frame ptr
	movl	d2,sp@-			| push trap type
	jbsr	_C_LABEL(nodb_trap)	| handle the trap
	addql	#8,sp			| pop args
Lbrkpt3:
	| The stack pointer may have been modified, or
	| data below it modified (by kgdb push call),
	| so push the hardware frame at the current sp
	| before restoring registers and returning.
	movl	sp@(FR_SP),a0		| modified sp
	lea	sp@(FR_SIZE),a1		| end of our frame
	movl	a1@-,a0@-		| copy 2 longs with
	movl	a1@-,a0@-		| ... predecrement
	movl	a0,sp@(FR_SP)		| sp = h/w frame
	moveml	sp@+,#0x7FFF		| restore all but sp
	movl	sp@,sp			| ... and sp
	rte				| all done

/*
 * Trap 12 is the entry point for the cachectl "syscall"
 *	cachectl(command, addr, length)
 * command in d0, addr in a1, length in d1
 */
GLOBAL(trap12)
	movl	d1,sp@-			| push length
	movl	a1,sp@-			| push addr
	movl	d0,sp@-			| push command
	jbsr	_C_LABEL(cachectl)	| do it
	lea	sp@(12),sp		| pop args
	jra	_ASM_LABEL(rei)		| all done

/*
 * Trap 1 is sigreturn
 */
ENTRY_NOPROFILE(trap1)
	jra	_ASM_LABEL(sigreturn)

/*
 * Trap 2 - trace trap
 *
 * XXX SunOS uses this for a cache flush!  What do we do here?
 * XXX
 * XXX  movl    #IC_CLEAR,d0
 * XXX  movc    d0,cacr
 * XXX  rte
 */
ENTRY_NOPROFILE(trap2)
	jra     _C_LABEL(trace)

/*
 * Interrupt handlers.  Most are auto-vectored,
 * and hard-wired the same way on all sun3 models.
 * Format in the stack is:
 *   d0,d1,a0,a1, sr, pc, vo
 */

#define INTERRUPT_SAVEREG \
	moveml	#0xC0C0,sp@-

#define INTERRUPT_RESTORE \
	moveml	sp@+,#0x0303

/*
 * This is the common auto-vector interrupt handler,
 * for which the CPU provides the vector=0x18+level.
 * These are installed in the interrupt vector table.
 */
	.align	2
GLOBAL(_isr_autovec)
	INTERRUPT_SAVEREG
	movw	sp@(22),sp@-		| push exception vector info
	clrw	sp@-
	jbsr	_C_LABEL(isr_autovec)	| C dispatcher
	addql	#4,sp
	INTERRUPT_RESTORE
	jra	_ASM_LABEL(rei)

/* clock: see clock.c */
	.align	2
GLOBAL(_isr_clock)
	INTERRUPT_SAVEREG 	| save a0, a1, d0, d1
	movl	_clock_va, a0
	movl	_interrupt_reg, a1
	tstb a0@(INTERSIL_INTR_OFFSET)
	andb #~IREG_CLOCK_ENAB_5, a1@
	orb #IREG_CLOCK_ENAB_5, a1@
	tstb a0@(INTERSIL_INTR_OFFSET)
| used to have "timebomb" check here...
	lea	sp@(16),a1		| a1 = &clockframe
	movl	a1,sp@-
	jbsr	_C_LABEL(clock_intr)
	addql	#4,sp
	INTERRUPT_RESTORE
	jra	_ASM_LABEL(rei)

| Handler for all vectored interrupts (i.e. VME interrupts)
	.align	2
GLOBAL(_isr_vectored)
	INTERRUPT_SAVEREG
	movw	sp@(22),sp@-		| push exception vector info
	clrw	sp@-
	jbsr	_C_LABEL(isr_vectored)	| C dispatcher
	addql	#4,sp			|
	INTERRUPT_RESTORE
	jra	_ASM_LABEL(rei)		| all done

#undef	INTERRUPT_SAVEREG
#undef	INTERRUPT_RESTORE

/* interrupt counters (needed by vmstat) */
GLOBAL(intrnames)
	.asciz	"spur"	| 0
	.asciz	"lev1"	| 1
	.asciz	"lev2"	| 2
	.asciz	"lev3"	| 3
	.asciz	"lev4"	| 4
	.asciz	"clock"	| 5
	.asciz	"lev6"	| 6
	.asciz	"nmi"	| 7
GLOBAL(eintrnames)

	.data
	.even
GLOBAL(intrcnt)
	.long	0,0,0,0,0,0,0,0,0,0
GLOBAL(eintrcnt)
	.text

/*
 * Emulation of VAX REI instruction.
 *
 * This code is (mostly) un-altered from the hp300 code,
 * except that sun machines do not need a simulated SIR
 * because they have a real software interrupt register.
 *
 * This code deals with checking for and servicing ASTs
 * (profiling, scheduling) and software interrupts (network, softclock).
 * We check for ASTs first, just like the VAX.  To avoid excess overhead
 * the T_ASTFLT handling code will also check for software interrupts so we
 * do not have to do it here.  After identifying that we need an AST we
 * drop the IPL to allow device interrupts.
 *
 * This code is complicated by the fact that sendsig may have been called
 * necessitating a stack cleanup.
 */

ASGLOBAL(rei)
#ifdef	DIAGNOSTIC
	tstl	_C_LABEL(panicstr)	| have we paniced?
	jne	Ldorte			| yes, do not make matters worse
#endif
	tstl	_C_LABEL(astpending)	| AST pending?
	jeq	Ldorte			| no, done
Lrei1:
	btst	#5,sp@			| yes, are we returning to user mode?
	jne	Ldorte			| no, done
	movw	#PSL_LOWIPL,sr		| lower SPL
	clrl	sp@-			| stack adjust
	moveml	#0xFFFF,sp@-		| save all registers
	movl	usp,a1			| including
	movl	a1,sp@(FR_SP)		|    the users SP
	clrl	sp@-			| VA == none
	clrl	sp@-			| code == none
	movl	#T_ASTFLT,sp@-		| type == async system trap
	jbsr	_C_LABEL(trap)		| go handle it
	lea	sp@(12),sp		| pop value args
	movl	sp@(FR_SP),a0		| restore user SP
	movl	a0,usp			|   from save area
	movw	sp@(FR_ADJ),d0		| need to adjust stack?
	jne	Laststkadj		| yes, go to it
	moveml	sp@+,#0x7FFF		| no, restore most user regs
	addql	#8,sp			| toss SP and stack adjust
	rte				| and do real RTE
Laststkadj:
	lea	sp@(FR_HW),a1		| pointer to HW frame
	addql	#8,a1			| source pointer
	movl	a1,a0			| source
	addw	d0,a0			|  + hole size = dest pointer
	movl	a1@-,a0@-		| copy
	movl	a1@-,a0@-		|  8 bytes
	movl	a0,sp@(FR_SP)		| new SSP
	moveml	sp@+,#0x7FFF		| restore user registers
	movl	sp@,sp			| and our SP
Ldorte:
	rte				| real return

/*
 * Initialization is at the beginning of this file, because the
 * kernel entry point needs to be at zero for compatibility with
 * the Sun boot loader.  This works on Sun machines because the
 * interrupt vector table for reset is NOT at address zero.
 * (The MMU has a "boot" bit that forces access to the PROM)
 */

/*
 * Use common m68k sigcode.
 */
#include <m68k/m68k/sigcode.s>

	.text

/*
 * Primitives
 */

/*
 * Use common m68k support routines.
 */
#include <m68k/m68k/support.s>

BSS(want_resched,4)

/*
 * Use common m68k process manipulation routines.
 */
#include <m68k/m68k/proc_subr.s>

| Message for Lbadsw panic
Lsw0:
	.asciz	"cpu_switch"
	.even

	.data
GLOBAL(masterpaddr)		| XXX compatibility (debuggers)
GLOBAL(curpcb)
	.long	0
ASBSS(nullpcb,SIZEOF_PCB)
	.text

/*
 * At exit of a process, do a cpu_switch for the last time.
 * Switch to a safe stack and PCB, and deallocate the process's resources.
 * The ipl is high enough to prevent the memory from being reallocated.
 */
ENTRY(switch_exit)
	movl	sp@(4),a0		| struct proc *p
					| save state into garbage pcb
	movl	#_ASM_LABEL(nullpcb),_C_LABEL(curpcb)
	lea	_ASM_LABEL(tmpstk),sp	| goto a tmp stack
	movl	a0,sp@-			| pass proc ptr down

        /* Schedule the vmspace and stack to be freed. */
	movl    a0,sp@-                 | exit2(p)
	jbsr    _C_LABEL(exit2)
	lea     sp@(4),sp               | pop args

	jra	_C_LABEL(cpu_switch)

/*
 * When no processes are on the runq, cpu_switch() branches to idle
 * to wait for something to come ready.
 */
	.data
GLOBAL(Idle_count)
	.long   0
	.text

Lidle:
	stop	#PSL_LOWIPL
GLOBAL(_Idle)
	movw	#PSL_HIGHIPL,sr
	addql   #1, _C_LABEL(Idle_count)
	tstl	_C_LABEL(whichqs)
	jeq	Lidle
	movw	#PSL_LOWIPL,sr
	jra	Lsw1

Lbadsw:
	movl	#Lsw0,sp@-
	jbsr	_C_LABEL(panic)
	/*NOTREACHED*/

/*
 * cpu_switch()
 * Hacked for sun3
 * XXX - Arg 1 is a proc pointer (curproc) but this doesn't use it.
 * XXX - Sould we use p->p_addr instead of curpcb? -gwr
 */
ENTRY(cpu_switch)
	movl	_C_LABEL(curpcb),a1	| current pcb
	movw	sr,a1@(PCB_PS)		| save sr before changing ipl
#ifdef notyet
	movl	_C_LABEL(curproc),sp@-	| remember last proc running
#endif
	clrl	_C_LABEL(curproc)

Lsw1:
	/*
	 * Find the highest-priority queue that isn't empty,
	 * then take the first proc from that queue.
	 */
	clrl	d0
	lea	_C_LABEL(whichqs),a0
	movl	a0@,d1
Lswchk:
	btst	d0,d1
	jne	Lswfnd
	addqb	#1,d0
	cmpb	#32,d0
	jne	Lswchk
	jra	_C_LABEL(_Idle)
Lswfnd:
	movw	#PSL_HIGHIPL,sr		| lock out interrupts
	movl	a0@,d1			| and check again...
	bclr	d0,d1
	jeq	Lsw1			| proc moved, rescan
	movl	d1,a0@			| update whichqs
	moveq	#1,d1			| double check for higher priority
	lsll	d0,d1			| process (which may have snuck in
	subql	#1,d1			| while we were finding this one)
	andl	a0@,d1
	jeq	Lswok			| no one got in, continue
	movl	a0@,d1
	bset	d0,d1			| otherwise put this one back
	movl	d1,a0@
	jra	Lsw1			| and rescan
Lswok:
	movl	d0,d1
	lslb	#3,d1			| convert queue number to index
	addl	#_qs,d1			| locate queue (q)
	movl	d1,a1
	cmpl	a1@(P_FORW),a1		| anyone on queue?
	jeq	Lbadsw			| no, panic
	movl	a1@(P_FORW),a0		| p = q->p_forw
	movl	a0@(P_FORW),a1@(P_FORW)	| q->p_forw = p->p_forw
	movl	a0@(P_FORW),a1		| q = p->p_forw
	movl	a0@(P_BACK),a1@(P_BACK)	| q->p_back = p->p_back
	cmpl	a0@(P_FORW),d1		| anyone left on queue?
	jeq	Lsw2			| no, skip
	movl	_C_LABEL(whichqs),d1
	bset	d0,d1			| yes, reset bit
	movl	d1,_C_LABEL(whichqs)
Lsw2:
	movl	a0,_C_LABEL(curproc)
	clrl	_C_LABEL(want_resched)
#ifdef notyet
	movl	sp@+,a1			| XXX - Make this work!
	cmpl	a0,a1			| switching to same proc?
	jeq	Lswdone			| yes, skip save and restore
#endif
	/*
	 * Save state of previous process in its pcb.
	 */
	movl	_C_LABEL(curpcb),a1
	moveml	#0xFCFC,a1@(PCB_REGS)	| save non-scratch registers
	movl	usp,a2			| grab USP (a2 has been saved)
	movl	a2,a1@(PCB_USP)		| and save it

	tstl	_C_LABEL(fputype)	| Do we have an fpu?
	jeq	Lswnofpsave		| No?  Then don't try save.
	lea	a1@(PCB_FPCTX),a2	| pointer to FP save area
	fsave	a2@			| save FP state
	tstb	a2@			| null state frame?
	jeq	Lswnofpsave		| yes, all done
	fmovem	fp0-fp7,a2@(FPF_REGS)		| save FP general regs
	fmovem	fpcr/fpsr/fpi,a2@(FPF_FPCR)	| save FP control regs
Lswnofpsave:

	/*
	 * Now that we have saved all the registers that must be
	 * preserved, we are free to use those registers until
	 * we load the registers for the switched-to process.
	 * In this section, keep:  a0=curproc, a1=curpcb
	 */

#ifdef DIAGNOSTIC
	tstl	a0@(P_WCHAN)
	jne	Lbadsw
	cmpb	#SRUN,a0@(P_STAT)
	jne	Lbadsw
#endif
	clrl	a0@(P_BACK)		| clear back link
	movl	a0@(P_ADDR),a1		| get p_addr
	movl	a1,_C_LABEL(curpcb)

	/*
	 * Load the new VM context (new MMU root pointer)
	 */
	movl	a0@(P_VMSPACE),a2	| vm = p->p_vmspace
#ifdef DIAGNOSTIC
	tstl	a2			| vm == VM_MAP_NULL?
	jeq	Lbadsw			| panic
#endif

	/*
	 * Call pmap_activate() to set the MMU context register
	 */
	movl	a2@(VM_PMAP),a2		| pmap = &vm.vm_map.pmap
	pea	a2@			| push pmap
	jbsr	_C_LABEL(pmap_activate)	| pmap_activate(pmap)
	addql	#4,sp
	movl	_C_LABEL(curpcb),a1	| restore p_addr
| Note: pmap_activate will clear the cache if needed.

	/*
	 * Reload the registers for the new process.
	 * After this point we can only use d0,d1,a0,a1
	 */
	moveml	a1@(PCB_REGS),#0xFCFC	| reload registers
	movl	a1@(PCB_USP),a0
	movl	a0,usp			| and USP

	tstl	_C_LABEL(fputype)	| If we don't have an fpu,
	jeq	Lres_skip		|  don't try to restore it.
	lea	a1@(PCB_FPCTX),a0	| pointer to FP save area
	tstb	a0@			| null state frame?
	jeq	Lresfprest		| yes, easy
	fmovem	a0@(FPF_FPCR),fpcr/fpsr/fpi	| restore FP control regs
	fmovem	a0@(FPF_REGS),fp0-fp7		| restore FP general regs
Lresfprest:
	frestore a0@			| restore state
Lres_skip:
	movw	a1@(PCB_PS),d0		| no, restore PS
#ifdef DIAGNOSTIC
	btst	#13,d0			| supervisor mode?
	jeq	Lbadsw			| no? panic!
#endif
	movw	d0,sr			| OK, restore PS
	moveq	#1,d0			| return 1 (for alternate returns)
	rts

/*
 * savectx(pcb)
 * Update pcb, saving current processor state.
 */
ENTRY(savectx)
	movl	sp@(4),a1
	movw	sr,a1@(PCB_PS)
	movl	usp,a0			| grab USP
	movl	a0,a1@(PCB_USP)		| and save it
	moveml	#0xFCFC,a1@(PCB_REGS)	| save non-scratch registers

	tstl	_C_LABEL(fputype)	| Do we have FPU?
	jeq	Lsavedone		| No?  Then don't save state.
	lea	a1@(PCB_FPCTX),a0	| pointer to FP save area
	fsave	a0@			| save FP state
	tstb	a0@			| null state frame?
	jeq	Lsavedone		| yes, all done
	fmovem	fp0-fp7,a0@(FPF_REGS)		| save FP general regs
	fmovem	fpcr/fpsr/fpi,a0@(FPF_FPCR)	| save FP control regs
Lsavedone:
	moveq	#0,d0			| return 0
	rts

/* suline() */
/* TBIA, TBIS, TBIAS, TBIAU */

/*
 * Invalidate instruction cache
 */
ENTRY(ICIA)
	movl	#IC_CLEAR,d0
	movc	d0,cacr			| invalidate i-cache
	rts

/* DCIA, DCIS */

/*
 * Invalidate data cache.
 */
ENTRY(DCIU)
	rts

/* ICPL, ICPP, DCPL, DCPP, DCPA, DCFL, DCFP */
/* PCIA, ecacheon, ecacheoff */

/*
 * Get callers current SP value.
 * Note that simply taking the address of a local variable in a C function
 * doesn't work because callee saved registers may be outside the stack frame
 * defined by A6 (e.g. GCC generated code).
 *
 * [I don't think the ENTRY() macro will do the right thing with this -- glass]
 */
GLOBAL(getsp)
	movl	sp,d0			| get current SP
	addql	#4,d0			| compensate for return address
	rts

ENTRY(getsfc)
	movc	sfc,d0
	rts

ENTRY(getdfc)
	movc	dfc,d0
	rts

ENTRY(getvbr)
	movc vbr, d0
	rts

ENTRY(setvbr)
	movl sp@(4), d0
	movc d0, vbr
	rts

/* loadustp, ptest_addr */

/*
 * Set processor priority level calls.  Most are implemented with
 * inline asm expansions.  However, we need one instantiation here
 * in case some non-optimized code makes external references.
 * Most places will use the inlined function param.h supplies.
 */

ENTRY(_getsr)
	clrl	d0
	movw	sr, d0
	rts

ENTRY(_spl)
	clrl	d0
	movw	sr,d0
	movl	sp@(4),d1
	movw	d1,sr
	rts
	
ENTRY(_splraise)
	clrl	d0
	movw	sr,d0
	movl	d0,d1
	andl	#PSL_HIGHIPL,d1		| old &= PSL_HIGHIPL
	cmpl	sp@(4),d1		| (old - new)
	bge	Lsplr
	movl	sp@(4),d1
	movw	d1,sr
Lsplr:
	rts

/*
 * Save and restore 68881 state.
 */
ENTRY(m68881_save)
	movl	sp@(4),a0		| save area pointer
	fsave	a0@			| save state
	tstb	a0@			| null state frame?
	jeq	Lm68881sdone		| yes, all done
	fmovem fp0-fp7,a0@(FPF_REGS)		| save FP general regs
	fmovem fpcr/fpsr/fpi,a0@(FPF_FPCR)	| save FP control regs
Lm68881sdone:
	rts

ENTRY(m68881_restore)
	movl	sp@(4),a0		| save area pointer
	tstb	a0@			| null state frame?
	jeq	Lm68881rdone		| yes, easy
	fmovem	a0@(FPF_FPCR),fpcr/fpsr/fpi	| restore FP control regs
	fmovem	a0@(FPF_REGS),fp0-fp7		| restore FP general regs
Lm68881rdone:
	frestore a0@			| restore state
	rts

/*
 * _delay(unsigned N)
 * Delay for at least (N/256) microseconds.
 * This routine depends on the variable:  delay_divisor
 * which should be set based on the CPU clock rate.
 * XXX: Currently this is set in sun3_startup.c based on the
 * XXX: CPU model but this should be determined at run time...
 */
GLOBAL(_delay)
	| d0 = arg = (usecs << 8)
	movl	sp@(4),d0
	| d1 = delay_divisor;
	movl	_C_LABEL(delay_divisor),d1
L_delay:
	subl	d1,d0
	jgt	L_delay
	rts


| Define some addresses, mostly so DDB can print useful info.
| Not using C_LABEL() here because these symbols are never
| referenced by any C code, and if the leading underscore
| ever goes away, these lines turn into syntax errors...
	.set	_kernbase,KERNBASE
	.set	_dvma_base,DVMA_SPACE_START
	.set	_prom_start,MONSTART
	.set	_prom_base,PROM_BASE

|The end!