locore.s

著名的AT&T UNIX v6 源码

	.set	HIGH,31		# mask for total disable
	.set	MCKVEC,4	# offset into Scbbase of machine check vector

# Trap vectors and C interface for Vax

#
#
#
# System control block
#

	.set	INTSTK,1	# handle this interrupt on the interrupt stack
	.set	HALT,3		# halt if this interrupt occurs
	.align	9
	.globl	Scbbase
Scbbase:
	.long	Xrandom + HALT	# unused
	.long	Xmachcheck + HALT	# machine check interrupt
	.long	Xkspnotval + HALT	# kernal stack not valid
	.long	Xpowfail + HALT	# power fail
	.long	Xprivinflt	# privileged instruction 
	.long	Xxfcflt		# xfc instruction 
	.long	Xresopflt	# reserved operand 
	.long	Xresadflt	# reserved addressing 
	.long	Xprotflt	# protection 
	.long	Xsegflt		# segmentation 
	.long	Xtracep		# trace pending
	.long	Xbptflt		# bpt instruction
	.long	Xcompatflt	# compatibility mode fault
	.long	Xarithtrap	# arithmetic trap
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xsyscall	# chmk
	.long	Xchme+HALT		# chme
	.long	Xchms+HALT		# chms
	.long	Xchmu+HALT		# chmu
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# software level 1
	.long	Xrandom + HALT	# software level 2 (asts)
	.long	Xresched	# reschedule nudge
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
ubabase:
	.long	Xclockint + INTSTK	# clock
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xconsrint + INTSTK	# console receiver 
	.long	Xconsxint + INTSTK	# console transmitter

#	I/O vectors

# IPL 14
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xua0int + INTSTK	# UBA 0 br4
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused

# IPL 15
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xua0int + INTSTK	# UBA 0 br5
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xmba0int + INTSTK	# mass bus adapter 0
	.long	Xmba1int + INTSTK	# mass bus adapter 1
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused

# IPL 16
	.long	Xrandom + HALT		# unused
	.long	Xrandom + HALT		# unused
	.long	Xrandom + HALT		# unused
	.long	Xua0int + INTSTK	# UBA 0 br6
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused

# IPL 17
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused
	.long	Xrandom + HALT	# unused


#  0x200
# Produce a core image dump on mag tape
	.globl	doadump
doadump:
	movl	sp,dumpstack	# save stack pointer
	movab	dumpstack,sp	# reinit stack
	mfpr	$PCBB,-(sp)	# save u-area pointer
	mfpr	$MAPEN,-(sp)	# save value
	mfpr	$IPL,-(sp)	# ...
	mtpr	$0,$MAPEN		# turn off memory mapping
	mtpr	$HIGH,$IPL		# disable interrupts
	pushr	$0x3fff			# save regs 0 - 13
	calls	$0,_dump	# produce dump
	halt

	.data
	.align	2
	.globl	dumpstack
	.space	58*4		# seperate stack for tape dumps
dumpstack: 
	.space	4
	.text


# I/O interrupt vector routines
#

# Catch random or unexpected interrupts

	.align	2
Xrandom:
Xmachcheck:
Xkspnotval:
Xpowfail:
Xchme:
Xchms:
Xchmu:
	halt

# Massbus 0 adapter interrupts

	.align	2
Xmba0int:
	pushr	$0x3f		# save r0 - r5
	movab	MBA0_CSR,r0	# point at mba regs
	movl	MBA_AS(r0),r1		# get attn summary bits
	cvtwl	r1,-(sp)		# push attn summary as arg
	pushl	MBA_SR(r0)	# pass sr as argument
	mnegl	$1,MBA_SR(r0)	# clear attention bit
	calls	$2,_hpintr	# call rp06 interrupt dispatcher
	brw 	int_ret		# merge with common interrupt code


# Massbus 1 adapter interrupts

	.align	2
Xmba1int:
	pushr	$0x3f
	movab	MBA1_CSR,r0
	pushl	MBA_AS(r0)
	mnegl	$1,MBA_AS(r0)
	pushl	MBA_SR(r0)		# pass cr as argument_
	mnegl	$1,MBA_SR(r0)	# clear attention bit
	calls	$2,_htintr	# call te16 interrupt dispatcher
	brw 	int_ret		# return from interrupt


# Unibus adapter interrupts

	.align	2
Xua0int:	#  UBA 0 interrupts
	pushr	$0x3f  #  save regs 0-5
	pushab	UBA0  # save UBA base addr
	brb	Xuacom  #  jump to common code
Xua1int :	#  UBA 1 interrupts
Xuacom :	#  common code for UBA interrupts
	popr	$1		# UBA base addr
	mfpr	$IPL,r2		# get br level
	movl	UBR_OFF-20*4(r0)[r2],r3	# get unibus device vector
	bleq	ubasrv  # branch if zero vector or UBA service required
#  normal UBA interrupt point - device on a UBA has generated an
#    interrupt - r3 holds interrupt vector
ubanorm :
	movl	_UNIvec(r3),r1  #  get interrupt service routine address
#			and controller code from UNIBUS vector area
	extzv	$27,$4,r1,-(sp)  #  controller code is in 4 most
#				significant bits-1 of ISR addr
	bicl2	$0x78000000,r1  #  clear code
	calls	$1,(r1)  #  call ISR
	brw	int_ret  #  go to common interrupt return
#  here for zero or negative UBA interrupt vector.
#  negative vector -> UBA requires service
ubasrv :
	beql	ubapass
#
#  UBA service required
#  The following 'printf' calls should probably be replaced
#    with calls to an error logger and/or some corrective action.
	bitl	$CFGFLT,UCN_OFF(r0)  #  any SBI faults ?
	beql	UBAflt
	pushr	$0xf  #  save regs 0-3
	pushab	SBImsg
	calls	$1,_printf
	popr	$0xf
	halt
#
#  no SBI fault bits set in UBA config reg - must be
#    some error bits set in UBA status reg
UBAflt :
	movl	UST_OFF(r0),r2  #  UBA status reg
	pushr	$0xf  #  save regs 0-3
	pushr	r2
	pushab	UBAmsg
	calls	$2,_printf
	popr	$0xf
	movl	r2,UST_OFF(r0)  #  clear error bits
	bicl2	$0x80000000,r1  #  clear neg bit in vector
	bneq	ubanorm  #  branch if normal UBA interrupt to process
	brb 	int_ret		# restore regs and return
#
#  zero interrupt vector - print message & continue
ubapass :
	pushr	$0xf
	pushab	ZERmsg
	calls	$1,_printf
	popr	$0xf
	brb	int_ret


# Console receiver interrupt

	.align	2
Xconsrint:
	pushr	$0x3f		# save registers 0 - 5
	calls	$0,_consrint
	brb 	int_ret		# merge


# Console transmit interrupt
	.align	2
Xconsxint:
	pushr	$0x3f		# save registers 0 - 5
	calls	$0,_consxint
	brb 	int_ret


# Clock interrupt
	.align	2
Xclockint:
	pushr	$0x3f		# save regs 0 - 5
	pushl	4+6*4(sp)	# push psl
	pushl	4+6*4(sp)	# push pc
	calls	$2,_clock
	brb 	int_ret


#
# Common code for interrupts
# At this point, the interrupt stack looks like:
#
#		 ___________
#		|    r0     | :isp
#		|-----------|
#		|    ...    |
#		|-----------|
#		|    r5     |
#		|-----------|
#		|    pc     |
#		|-----------|
#		|    psl    |
#		|___________|


int_ret:
	bbssi	$0,idleflag,int_r0		# set idle escape flag (no wait instr)
int_r0:
	popr	$0x3f		# restore regs 0 - 5
	bitl	$PSL_CURMOD,4(sp)	# interrupt from user mode?
	beql	int_r1		# no, from kernal, just rei
	tstb	_runrun		# should we reschedule?
	beql	int_r1		# no, just rei
#
# If here, interrupt from user mode, and time to reschedule.
#	to do this, we set a software level 3 interrupt to
#	change to kernal mode, switch stacks,
#	and format kernal stack for a `qswitch' trap to force
#	a reschedule.
#
	mtpr	$0x18,$IPL	# make sure int won't happen now
	mtpr	$3,$SIRR	# request level 3 software interrupt
int_r1:
	rei 			# return to interrupted process

#
# Trap and fault vector routines
#

#	Reschedule trap (Software level 3 interrupt)
	.align	2
Xresched:
	movpsl	-(sp)	# get ps
	bicl2	$PSL_IPL,(sp)	# lower ipl
	pushab	resc1		# push pc
	rei			# lower ipl, jump to resc1

resc1:
	pushl	$0			# dummy code
	pushl	$RESCHED	# type
	brb 	alltraps	# merge


#	privileged instruction fault
	.align	2
Xprivinflt:
	pushl	$0		# push dummy code
	pushl	$PRIVINFLT	# push type
	brb 	alltraps	# merge



#	xfc instruction fault
	.align	2
Xxfcflt:
	pushl	$0		# push dummy code value
	pushl	$XFCFLT		# push type value
	brb 	alltraps	# merge


#	reserved operand fault
	.align	2
Xresopflt:
	pushl	$0		# push dummy code value
	pushl	$RESOPFLT	# push type value
	brb 	alltraps	# merge


#	reserved addressing mode fault
	.align	2
Xresadflt:
	pushl	$0		# push dummy code value
	pushl	$RESADFLT	# push type value
	brb 	alltraps	# merge with common code


#	bpt instruction fault
	.align	2
Xbptflt:
	pushl	$0		# push dummy code value
	pushl	$BPTFLT		# push type value
	brb 	alltraps	# merge with common code

#	Compatibility mode fault
	.align	2
Xcompatflt:
	pushl	$COMPATFLT	# push type value
	brb 	alltraps	#merge with common code


#	Trace trap

	.align	2
Xtracep:
	pushl	$0		# push dummy code value
	pushl	$TRCTRAP	# push type value
	brb 	alltraps	# go do it

#	Arithmitic trap
	.align	2
Xarithtrap:
	pushl	$ARITHTRAP	# push type value
	brb 	alltraps	# merge with common code


#	Protection  fault

	.align	2
Xprotflt:
	blbs	(sp),Xsegflt		# check for pt length violation
	addl2	$4,sp		# pop fault param word 
	pushl	$PROTFLT
	brb 	alltraps

#	Segmentation fault

	.align	2
Xsegflt:
	addl2	$4,sp
	pushl	$SEGFLT
	brb 	alltraps




#
# CHMK trap (syscall trap)
#	on entry, kernal stack:
#
#		 ___________ 
#		|    code   | :ksp
#		|-----------|
#		|    pc     |
#		|-----------|
#		|    psl    |
#		|___________|
#
#
#
#	stack (parameters) at calls to _trap:
#
#		 ___________ 
#		|    ap     | :ksp
#		|-----------|
#		|    r0     |
#		|-----------|
#		|    ...    |
#		|-----------|
#		|    r13    |
#		|-----------|
#		|    usp    |
#		|-----------|
#		|    type   |
#		|-----------|
#		|    code   |
#		|-----------|
#		|    pc     |
#		|-----------|
#		|    psl    |
#		|___________|
#

	.align	2
Xsyscall:
	pushl	$SYSCALL	# push type value
alltraps:
	movq	8(sp),_u+PCB_PC	# save pc
	bitl	$PSL_CURMOD,12(sp)	# from user mode?
	beql	sysc1		# no
# Prepare arguments to _trap, note that type has already been pushed
	mfpr	$USP,-(sp)	# get usp
	pushr	$0x3fff		# registers 0 - 13
	pushl	ap		# ptr to syscall parameters
#
# Call _trap with wrong number of arguments
#   so args not popped by ret
#
	calls	$1,_trap
# Restore
	popr	$0x3fff		# restore regs 0 - 13
	mtpr	(sp)+,$USP	# restore usp
	addl2	$8,sp		# pop type, code
#
	bitl	$PSL_CURMOD,4(sp)		# are we returning to user mode?
	beql	sysc2		# no
# Return
	rei

sysc1:
	movab	emsg1,eptr	# set message pointer
	brb 	err_print	# print message and halt

sysc2:
	movab	emsg2,eptr	# pointer to error message
	brb 	err_print	# print msg and halt

#
# err_print
#	print message on console and die
#	message pointed to by eptr, terminated by zero byte.
#

err_print:
	mtpr	$HIGH,$IPL	# disable all interrupts
	mtpr	$0,$TXCS	# disable interrupts on console transmitter
eloop1:
	mfpr	$TXCS,ewk1	# get transmitter status
	bbc 	$TXCS_BRDY,ewk1,eloop1	# loop if not ready to transmit
	tstb	*eptr		# end of message?
	beql	eout		# yes, out of loop
	movzbl	*eptr,ewk1	# get byte of message
	incl	eptr		# bump pointer
	mtpr	ewk1,$TXDB	# give byte to transmitter
	brb 	eloop1		# loop

eout:
	halt

	.data
eptr:	.long	0
ewk1:	.long	0
	.text



#
# Initialization

#
#	IPL == 1F
#	MAPEN == off
#	SCBB, PCBB not set
#	SBR, SLR not set
#	ISP, KSP not set
#
	.globl	start
start:
	.word	0x0000
	mtpr	$HIGH,$IPL		# no interrupts yet
	mtpr	$Scbbase,$SCBB	# set SCBB
	mtpr	$_Sysmap,$SBR	# set SBR
	mtpr	$Syssize,$SLR	# set SLR
	mtpr	$_Sysmap,$P0BR	# set temp P0BR
	mtpr	$Syssize,$P0LR	# set temp P0LR
	movl	$_intstack+2048,sp	# set ISP
# initialize i/o adatpers
	movl	$1,PHYSMBA0+4	# init & interrupt enable
	movl	$4,PHYSMBA0+4	# init & interrupt enable
	movl	$1,PHYSMBA1+4	# init  interrupt enable
	movl	$4,PHYSMBA1+4	# init  interrupt enable
	movl	$1,PHYSUBA+4	# init  interrupt enable
	movl	$0x78,PHYSUBA+4	# init  interrupt enable

	movl	Scbbase+MCKVEC,r5	# save machine check entry
	movab	startint+INTSTK,Scbbase+MCKVEC	# set new vector address
#
# will now see how much memory there really is
#	in 64kb chunks, save number of bytes in r7
#
	mtpr	$HIGH-1,$IPL	# allow machine check interrupts
	clrl	r7
startlp:
	tstl	(r7)		# this chunk really there?
	acbl	$8096*1024-1,$64*1024,r7,startlp	# loop till machine check
	brb 	startint	# full load of memory, avoid .align
	.align	2
startint:
	mtpr	$0,$SBIFS		# clear sbi fault status
	movl	r5,Scbbase+MCKVEC	# restore machine check vector
	movl	$_intstack+2048,sp	# reset interrupt stack pointer

#	clear memory starting with unitialized data (kernal)
	movab	_edata,r6
	movab	_end+8096,r5	# clear uninitialized data and some slop
strtclr:
	clrq	(r6)
	acbl	r5,$8,r6,strtclr

#
#	initialize system page table
#
	movab	_etext+511,r1	# end of kernal text segment
	bbcc	$31,r1,strt1	# turn off high order bit
strt1:
	ashl	$-9,r1,r1	# last page of kernal text
	clrl	r2		# point at first kernal text page
strtlp1:
	bisl3	$PG_V|PG_KR,r2,_Sysmap[r2]	# initialize page table entry