locore.s

早期freebsd实现

#ifdef KGDB
	moveq	#T_TRACE,d0
	movw	sp@(FR_HW),d1		| get SSW
	andw	#PSL_S,d1		| from user mode?
	jeq	fault			| no, regular fault
	movl	d0,sp@-
	jbsr	_kgdb_trap_glue		| returns if no debugger
	addl	#4,sp
#endif
	moveq	#T_TRACE,d0
	jra	fault

/*
 * The sigreturn() syscall comes here.  It requires special handling
 * because we must open a hole in the stack to fill in the (possibly much
 * larger) original stack frame.
 */
sigreturn:
	lea	sp@(-84),sp		| leave enough space for largest frame
	movl	sp@(84),sp@		| move up current 8 byte frame
	movl	sp@(88),sp@(4)
	movl	#84,sp@-		| default: adjust by 84 bytes
	moveml	#0xFFFF,sp@-		| save user registers
	movl	usp,a0			| save the user SP
	movl	a0,sp@(FR_SP)		|   in the savearea
	movl	#SYS_sigreturn,sp@-	| push syscall number
	jbsr	_syscall		| handle it
	addql	#4,sp			| pop syscall#
	movl	sp@(FR_SP),a0		| grab and restore
	movl	a0,usp			|   user SP
	lea	sp@(FR_HW),a1		| pointer to HW frame
	movw	sp@(FR_ADJ),d0		| do we need to adjust the stack?
	jeq	Lsigr1			| no, just continue
	moveq	#92,d1			| total size
	subw	d0,d1			|  - hole size = frame size
	lea	a1@(92),a0		| destination
	addw	d1,a1			| source
	lsrw	#1,d1			| convert to word count
	subqw	#1,d1			| minus 1 for dbf
Lsigrlp:
	movw	a1@-,a0@-		| copy a word
	dbf	d1,Lsigrlp		| continue
	movl	a0,a1			| new HW frame base
Lsigr1:
	movl	a1,sp@(FR_SP)		| new SP value
	moveml	sp@+,#0x7FFF		| restore user registers
	movl	sp@,sp			| and our SP
	jra	rei			| all done

/*
 * Interrupt handlers.
 * All DIO device interrupts are auto-vectored.  Most can be configured
 * to interrupt in the range IPL3 to IPL5.  Here are our assignments:
 *
 *	Level 0:	Spurious: ignored.
 *	Level 1:	HIL
 *	Level 2:
 *	Level 3:	Internal HP-IB, DCM
 *	Level 4:	"Fast" HP-IBs, SCSI
 *	Level 5:	DMA, Ethernet, Built-in RS232 (DCA)
 *	Level 6:	Clock
 *	Level 7:	Non-maskable: parity errors, RESET key
 */
	.globl	_hilint, _intrhand, _hardclock, _nmihand, _dmaintr
	.globl	_dcafastservice

_spurintr:
	addql	#1,_intrcnt+0
	addql	#1,_cnt+V_INTR
	jra	rei

_lev1intr:
	moveml	#0xC0C0,sp@-
	jbsr	_hilint
	moveml	sp@+,#0x0303
	addql	#1,_intrcnt+4
	addql	#1,_cnt+V_INTR
	jra	rei

/*
 * Check for unbuffered serial port (DCA) interrupts first in an attempt
 * to minimize received character lossage.  Then we check for DMA activity
 * to reduce overhead there.
 */
_lev5intr:
	moveml	#0xC0C0,sp@-
	tstl	_dcafastservice		| unbuffered port active?
	jeq	Ltrydma			| no, check DMA
	clrl	sp@-			| yes, check DCA port 0
	jbsr	_dcaintr		|    first to avoid overflow
	addql	#4,sp
	tstl	d0			| did it belong to DCA?
	jeq	Ltrydma			| no, go try DMA
	moveml	sp@+,#0x0303
	addql	#1,_intrcnt+20
	addql	#1,_cnt+V_INTR
	jra	rei
Ltrydma:
	jbsr	_dmaintr		| check DMA channels
	tstl	d0 			| was it ours?
	jeq	Lnotdma			| no, go poll other devices
	moveml	sp@+,#0x0303
	addql	#1,_intrcnt+24
	addql	#1,_cnt+V_INTR
	jra	rei

_lev2intr:
_lev3intr:
_lev4intr:
	moveml	#0xC0C0,sp@-
Lnotdma:
	lea	_intrcnt,a0
	movw	sp@(22),d0		| use vector offset
	andw	#0xfff,d0		|   sans frame type
	addql	#1,a0@(-0x60,d0:w)	|     to increment apropos counter
	movw	sr,sp@-			| push current SR value
	clrw	sp@-			|    padded to longword
	jbsr	_intrhand		| handle interrupt
	addql	#4,sp			| pop SR
	moveml	sp@+,#0x0303
	addql	#1,_cnt+V_INTR
	jra	rei

_lev6intr:
#ifdef STACKCHECK
	.globl	_panicstr,_badkstack
	cmpl	#_kstack+NBPG,sp	| are we still in stack page?
	jcc	Lstackok		| yes, continue normally
	tstl	_curproc		| if !curproc could have switch_exited,
	jeq	Lstackok		|     might be on tmpstk
	tstl	_panicstr		| have we paniced?
	jne	Lstackok		| yes, do not re-panic
	movl	sp@(4),tmpstk-4		| no, copy common
	movl	sp@,tmpstk-8		|  frame info
	movl	sp,tmpstk-16		| no, save original SP
	lea	tmpstk-16,sp		| switch to tmpstk
	moveml	#0xFFFE,sp@-		| push remaining registers
	movl	#1,sp@-			| is an overflow
	jbsr	_badkstack		| badkstack(1, frame)
	addql	#4,sp
	moveml	sp@+,#0x7FFF		| restore most registers
	movl	sp@,sp			| and SP
Lstackok:
#endif
	moveml	#0xC0C0,sp@-		| save scratch registers
	CLKADDR(a0)
	movb	a0@(CLKSR),d0		| read clock status
Lclkagain:
	btst	#0,d0			| clear timer1 int immediately to
	jeq	Lnotim1			|  minimize chance of losing another
	movpw	a0@(CLKMSB1),d1		|  due to statintr processing delay
Lnotim1:
	btst	#2,d0			| timer3 interrupt?
	jeq	Lnotim3			| no, skip statclock
	movpw	a0@(CLKMSB3),d1		| clear timer3 interrupt
	addql	#1,_intrcnt+32		| count clock interrupts
	lea	sp@(16),a1		| a1 = &clockframe
	movl	d0,sp@-			| save status
	movl	a1,sp@-
	jbsr	_statintr		| statintr(&frame)
	addql	#4,sp
	movl	sp@+,d0			| restore pre-statintr status
	CLKADDR(a0)
Lnotim3:
	btst	#0,d0			| timer1 interrupt?
	jeq	Lrecheck		| no, skip hardclock
	addql	#1,_intrcnt+28		| count hardclock interrupts
	lea	sp@(16),a1		| a1 = &clockframe
	movl	a1,sp@-
#ifdef USELEDS
	.globl	_ledaddr, _inledcontrol, _ledcontrol, _hz
	tstl	_ledaddr		| using LEDs?
	jeq	Lnoled0			| no, skip this code
	movl	heartbeat,d0		| get tick count
	addql	#1,d0			|  increment
	movl	_hz,d1
	lsrl	#1,d1			| throb twice a second
	cmpl	d0,d1			| are we there yet?
	jne	Lnoled1			| no, nothing to do
	tstl	_inledcontrol		| already updating LEDs?
	jne	Lnoled2			| yes, skip it
	movl	#LED_PULSE,sp@-
	movl	#LED_DISK+LED_LANRCV+LED_LANXMT,sp@-
	clrl	sp@-
	jbsr	_ledcontrol		| toggle pulse, turn all others off
	lea	sp@(12),sp
Lnoled2:
	movql	#0,d0
Lnoled1:
	movl	d0,heartbeat
Lnoled0:
#endif
	jbsr	_hardclock		| hardclock(&frame)
	addql	#4,sp
	CLKADDR(a0)
Lrecheck:
	addql	#1,_cnt+V_INTR		| chalk up another interrupt
	movb	a0@(CLKSR),d0		| see if anything happened
	jmi	Lclkagain		|  while we were in hardclock/statintr
	moveml	sp@+,#0x0303		| restore scratch registers
	jra	rei			| all done

_lev7intr:
	addql	#1,_intrcnt+36
	clrl	sp@-
	moveml	#0xFFFF,sp@-		| save registers
	movl	usp,a0			| and save
	movl	a0,sp@(FR_SP)		|   the user stack pointer
	jbsr	_nmihand		| call handler
	movl	sp@(FR_SP),a0		| restore
	movl	a0,usp			|   user SP
	moveml	sp@+,#0x7FFF		| and remaining registers
	addql	#8,sp			| pop SP and stack adjust
	jra	rei			| all done

/*
 * Emulation of VAX REI instruction.
 *
 * 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 identifing 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.
 */
	.comm	_ssir,1
	.globl	_astpending
rei:
#ifdef STACKCHECK
	tstl	_panicstr		| have we paniced?
	jne	Ldorte1			| yes, do not make matters worse
#endif
	tstl	_astpending		| AST pending?
	jeq	Lchksir			| no, go check for SIR
Lrei1:
	btst	#5,sp@			| yes, are we returning to user mode?
	jne	Lchksir			| no, go check for SIR
	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	_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
#ifdef STACKCHECK
	jra	Ldorte
#else
	rte				| and do real RTE
#endif
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
#ifdef STACKCHECK
	jra	Ldorte
#else
	rte				| and do real RTE
#endif
Lchksir:
	tstb	_ssir			| SIR pending?
	jeq	Ldorte			| no, all done
	movl	d0,sp@-			| need a scratch register
	movw	sp@(4),d0		| get SR
	andw	#PSL_IPL7,d0		| mask all but IPL
	jne	Lnosir			| came from interrupt, no can do
	movl	sp@+,d0			| restore scratch register
Lgotsir:
	movw	#SPL1,sr		| prevent others from servicing int
	tstb	_ssir			| too late?
	jeq	Ldorte			| yes, oh well...
	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_SSIR,sp@-		| type == software interrupt
	jbsr	_trap			| go handle it
	lea	sp@(12),sp		| pop value args
	movl	sp@(FR_SP),a0		| restore
	movl	a0,usp			|   user SP
	moveml	sp@+,#0x7FFF		| and all remaining registers
	addql	#8,sp			| pop SP and stack adjust
#ifdef STACKCHECK
	jra	Ldorte
#else
	rte
#endif
Lnosir:
	movl	sp@+,d0			| restore scratch register
Ldorte:
#ifdef STACKCHECK
	movw	#SPL6,sr		| avoid trouble
	btst	#5,sp@			| are we returning to user mode?
	jne	Ldorte1			| no, skip it
	movl	a6,tmpstk-20
	movl	d0,tmpstk-76
	moveq	#0,d0
	movb	sp@(6),d0		| get format/vector
	lsrl	#3,d0			| convert to index
	lea	_exframesize,a6		|  into exframesize
	addl	d0,a6			|  to get pointer to correct entry
	movw	a6@,d0			| get size for this frame
	addql	#8,d0			| adjust for unaccounted for bytes
	lea	_kstackatbase,a6	| desired stack base
	subl	d0,a6			|   - frame size == our stack
	cmpl	a6,sp			| are we where we think?
	jeq	Ldorte2			| yes, skip it
	lea	tmpstk,a6		| will be using tmpstk
	movl	sp@(4),a6@-		| copy common
	movl	sp@,a6@-		|   frame info
	clrl	a6@-
	movl	sp,a6@-			| save sp
	subql	#4,a6			| skip over already saved a6
	moveml	#0x7FFC,a6@-		| push remaining regs (d0/a6/a7 done)
	lea	a6@(-4),sp		| switch to tmpstk (skip saved d0)
	clrl	sp@-			| is an underflow
	jbsr	_badkstack		| badkstack(0, frame)
	addql	#4,sp
	moveml	sp@+,#0x7FFF		| restore most registers
	movl	sp@,sp			| and SP
	rte
Ldorte2:
	movl	tmpstk-76,d0
	movl	tmpstk-20,a6
Ldorte1:
#endif
	rte				| real return

/*
 * Kernel access to the current processes kernel stack is via a fixed
 * virtual address.  It is at the same address as in the users VA space.
 * Umap contains the KVA of the first of UPAGES PTEs mapping VA _kstack.
 */
	.data
	.set	_kstack,USRSTACK
	.set	_kstackatbase,USRSTACK+UPAGES*NBPG-4
	.globl	_kstackatbase
_Umap:	.long	0
	.globl	_kstack, _Umap

#define	RELOC(var, ar)	\
	lea	var,ar;	\
	addl	a5,ar

/*
 * Initialization
 *
 * A5 contains physical load point from boot
 * VBR contains zero from ROM.  Exceptions will continue to vector
 * through ROM until MMU is turned on at which time they will vector
 * through our table (vectors.s).
 */
	.comm	_lowram,4

	.text
	.globl	_edata
	.globl	_etext,_end
	.globl	start
start:
	movw	#PSL_HIGHIPL,sr		| no interrupts
	RELOC(tmpstk, a0)
	movl	a0,sp			| give ourselves a temporary stack
	RELOC(_lowram, a0)
	movl	a5,a0@			| store start of physical memory
	movl	#CACHE_OFF,d0
	movc	d0,cacr			| clear and disable on-chip cache(s)

/* determine our CPU/MMU combo - check for all regardless of kernel config */
	movl	#INTIOBASE+MMUBASE,a1
	movl	#0x200,d0		| data freeze bit
	movc	d0,cacr			|   only exists on 68030
	movc	cacr,d0			| read it back
	tstl	d0			| zero?
	jeq	Lnot68030		| yes, we have 68020/68040
	RELOC(_mmutype, a0)		| no, we have 68030
	movl	#-1,a0@			| set to reflect 68030 PMMU
	RELOC(_machineid, a0)
	movl	#0x80,a1@(MMUCMD)	| set magic cookie
	movl	a1@(MMUCMD),d0		| read it back
	btst	#7,d0			| cookie still on?
	jeq	Lnot370			| no, 360 or 375
	movl	#0,a1@(MMUCMD)		| clear magic cookie
	movl	a1@(MMUCMD),d0		| read it back
	btst	#7,d0			| still on?
	jeq	Lisa370			| no, must be a 370
	movl	#5,a0@			| yes, must be a 340
	jra	Lstart1
Lnot370:
	movl	#3,a0@			| type is at least a 360
	movl	#0,a1@(MMUCMD)		| clear magic cookie2
	movl	a1@(MMUCMD),d0		| read it back
	btst	#16,d0			| still on?
	jeq	Lstart1			| no, must be a 360
	movl	#6,a0@			| yes, must be a 345/375
	jra	Lhaspac
Lisa370:
	movl	#4,a0@			| set to 370
Lhaspac:
	RELOC(_ectype, a0)
	movl	#-1,a0@			| also has a physical address cache
	jra	Lstart1
Lnot68030:
	bset	#31,d0			| data cache enable bit
	movc	d0,cacr			|   only exists on 68040
	movc	cacr,d0			| read it back
	tstl	d0			| zero?
	beq	Lis68020		| yes, we have 68020
	moveq	#0,d0			| now turn it back off
	movec	d0,cacr			|   before we access any data
	RELOC(_mmutype, a0)
	movl	#-2,a0@			| with a 68040 MMU
	RELOC(_ectype, a0)
	movl	#0,a0@			| and no cache (for now XXX)
#ifdef HPFPLIB
	RELOC(_processor, a0)
	movl	#3,a0@			| HP-UX style processor id
#endif
	RELOC(_machineid, a0)
	movl	a1@(MMUCMD),d0		| read MMU register
	lsrl	#8,d0			| get apparent ID
	cmpb	#6,d0			| id == 6?
	jeq	Lis33mhz		| yes, we have a 433s
	movl	#7,a0@			| no, we have a 380/425t
	jra	Lstart1
Lis33mhz:
	movl	#8,a0@			| 433s (XXX 425s returns same ID, ugh!)
	jra	Lstart1
Lis68020:
	movl	#1,a1@(MMUCMD)		| a 68020, write HP MMU location
	movl	a1@(MMUCMD),d0		| read it back
	btst	#0,d0			| non-zero?
	jne	Lishpmmu		| yes, we have HP MMU
	RELOC(_mmutype, a0)
	movl	#1,a0@			| no, we have PMMU
	RELOC(_machineid, a0)
	movl	#1,a0@			| and 330 CPU
	jra	Lstart1
Lishpmmu:
	RELOC(_ectype, a0)		| 320 or 350
	movl	#1,a0@			| both have a virtual address cache
	movl	#0x80,a1@(MMUCMD)	| set magic cookie
	movl	a1@(MMUCMD),d0		| read it back
	btst	#7,d0			| cookie still on?
	jeq	Lstart1			| no, just a 320
	RELOC(_machineid, a0)
	movl	#2,a0@			| yes, a 350

Lstart1:
	movl	#0,a1@(MMUCMD)		| clear out MMU again
/* initialize source/destination control registers for movs */
	moveq	#FC_USERD,d0		| user space
	movc	d0,sfc			|   as source
	movc	d0,dfc			|   and destination of transfers
/* initialize memory sizes (for pmap_bootstrap) */
	movl	#MAXADDR,d1		| last page
	moveq	#PGSHIFT,d2
	lsrl	d2,d1			| convert to page (click) number
	RELOC(_maxmem, a0)
	movl	d1,a0@			| save as maxmem
	movl	a5,d0			| lowram value from ROM via boot
	lsrl	d2,d0			| convert to page number
	subl	d0,d1			| compute amount of RAM present
	RELOC(_physmem, a0)
	movl	d1,a0@			| and physmem
/* configure kernel and proc0 VA space so we can get going */
	.globl	_Sysseg, _pmap_bootstrap, _avail_start
	movl	#_end,d5		| end of static kernel text/data
	addl	#NBPG-1,d5
	andl	#PG_FRAME,d5		| round to a page
	movl	d5,a4
	addl	a5,a4			| convert to PA
	pea	a5@			| firstpa
	pea	a4@			| nextpa
	RELOC(_pmap_bootstrap,a0)
	jbsr	a0@			| pmap_bootstrap(firstpa, nextpa)
	addql	#8,sp

/*
 * Prepare to enable MMU.
 * Since the kernel is not mapped logical == physical we must insure