locore.s

早期freebsd实现

_esigcode:

/*
 * Primitives
 */ 

#ifdef __STDC__
#define EXPORT(name)		.globl _ ## name; _ ## name:
#else
#define EXPORT(name)		.globl _/**/name; _/**/name:
#endif
#ifdef GPROF
#if __GNUC__ >= 2
#define		ENTRY(name)		EXPORT(name) link a6,\#0; jbsr mcount; unlk a6
#else
#define		ENTRY(name)		EXPORT(name) link a6,#0; jbsr mcount; unlk a6
#endif
#define ALTENTRY(name, rname) ENTRY(name); jra rname+12
#else
#define		ENTRY(name)		EXPORT(name)
#define ALTENTRY(name, rname)		ENTRY(name)
#endif

/*
 * For gcc2
 */
ENTRY(__main)
	rts

/*
 * copypage(fromaddr, toaddr)
 *
 * Optimized version of bcopy for a single page-aligned NBPG byte copy.
 */
ENTRY(copypage)
	movl	sp@(4),a0		| source address
	movl	sp@(8),a1		| destination address
	movl	#NBPG/32,d0		| number of 32 byte chunks
#if defined(LUNA2)
	cmpl	#-2,_mmutype		| 68040?
	jne	Lmlloop			| no, use movl
Lm16loop:
	.long	0xf6209000		| move16 a0@+,a1@+
	.long	0xf6209000		| move16 a0@+,a1@+
	subql	#1,d0
	jne	Lm16loop
	rts
#endif
Lmlloop:
	movl	a0@+,a1@+
	movl	a0@+,a1@+
	movl	a0@+,a1@+
	movl	a0@+,a1@+
	movl	a0@+,a1@+
	movl	a0@+,a1@+
	movl	a0@+,a1@+
	movl	a0@+,a1@+
	subql	#1,d0
	jne	Lmlloop
	rts

/*
 * copyinstr(fromaddr, toaddr, maxlength, &lencopied)
 *
 * Copy a null terminated string from the user address space into
 * the kernel address space.
 *
 * NOTE: maxlength must be < 64K (due to use of DBcc)
 */
ENTRY(copyinstr)
	movl	_curpcb,a0		| current pcb
	movl	#Lcisflt1,a0@(PCB_ONFAULT) | set up to catch faults
	movl	sp@(4),a0		| a0 = fromaddr
	movl	sp@(8),a1		| a1 = toaddr
	moveq	#0,d0
	movw	sp@(14),d0		| d0 = maxlength
	jlt	Lcisflt1		| negative count, error
	jeq	Lcisdone		| zero count, all done
	subql	#1,d0			| set up for dbeq
Lcisloop:
	movsb	a0@+,d1			| grab a byte
	nop
	movb	d1,a1@+			| copy it
	dbeq	d0,Lcisloop		| if !null and more, continue
	jne	Lcisflt2		| ran out of room, error
	moveq	#0,d0			| got a null, all done
Lcisdone:
	tstl	sp@(16)			| return length desired?
	jeq	Lcisret			| no, just return
	subl	sp@(4),a0		| determine how much was copied
	movl	sp@(16),a1		| return location
	movl	a0,a1@			| stash it
Lcisret:
	movl	_curpcb,a0		| current pcb
	clrl	a0@(PCB_ONFAULT) 	| clear fault addr
	rts
Lcisflt1:
	moveq	#EFAULT,d0		| copy fault
	jra	Lcisdone
Lcisflt2:
	moveq	#ENAMETOOLONG,d0	| ran out of space
	jra	Lcisdone	

/*
 * copyoutstr(fromaddr, toaddr, maxlength, &lencopied)
 *
 * Copy a null terminated string from the kernel
 * address space to the user address space.
 * NOTE: maxlength must be < 64K
 */
ENTRY(copyoutstr)
	movl	_curpcb,a0		| current pcb
	movl	#Lcosflt1,a0@(PCB_ONFAULT) | set up to catch faults
	movl	sp@(4),a0		| a0 = fromaddr
	movl	sp@(8),a1		| a1 = toaddr
	moveq	#0,d0
	movw	sp@(14),d0		| d0 = maxlength
	jlt	Lcosflt1		| negative count, error
	jeq	Lcosdone		| zero count, all done
	subql	#1,d0			| set up for dbeq
Lcosloop:
	movb	a0@+,d1			| grab a byte
	movsb	d1,a1@+			| copy it
	nop
	dbeq	d0,Lcosloop		| if !null and more, continue
	jne	Lcosflt2		| ran out of room, error
	moveq	#0,d0			| got a null, all done
Lcosdone:
	tstl	sp@(16)			| return length desired?
	jeq	Lcosret			| no, just return
	subl	sp@(4),a0		| determine how much was copied
	movl	sp@(16),a1		| return location
	movl	a0,a1@			| stash it
Lcosret:
	movl	_curpcb,a0		| current pcb
	clrl	a0@(PCB_ONFAULT) 	| clear fault addr
	rts
Lcosflt1:
	moveq	#EFAULT,d0		| copy fault
	jra	Lcosdone
Lcosflt2:
	moveq	#ENAMETOOLONG,d0	| ran out of space
	jra	Lcosdone	

/*
 * copystr(fromaddr, toaddr, maxlength, &lencopied)
 *
 * Copy a null terminated string from one point to another in
 * the kernel address space.
 *
 * NOTE: maxlength must be < 64K (due to use of DBcc)
 */
ENTRY(copystr)
	movl	sp@(4),a0		| a0 = fromaddr
	movl	sp@(8),a1		| a1 = toaddr
	moveq	#0,d0
	movw	sp@(14),d0		| d0 = maxlength
	jlt	Lcsflt1			| negative count, error
	jeq	Lcsdone			| zero count, all done
	subql	#1,d0			| set up for dbeq
Lcsloop:
	movb	a0@+,a1@+		| copy a byte
	dbeq	d0,Lcsloop		| if !null and more, continue
	jne	Lcsflt2			| ran out of room, error
	moveq	#0,d0			| got a null, all done
Lcsdone:
	tstl	sp@(16)			| return length desired?
	jeq	Lcsret			| no, just return
	subl	sp@(4),a0		| determine how much was copied
	movl	sp@(16),a1		| return location
	movl	a0,a1@			| stash it
Lcsret:
	rts
Lcsflt1:
	moveq	#EFAULT,d0		| copy fault
	jra	Lcsdone
Lcsflt2:
	moveq	#ENAMETOOLONG,d0	| ran out of space
	jra	Lcsdone	

/* 
 * Copyin(from_user, to_kernel, len)
 * Copyout(from_kernel, to_user, len)
 *
 * Copy specified amount of data between kernel and user space.
 *
 * XXX both use the DBcc instruction which has 16-bit limitation so only
 * 64k units can be copied, where "unit" is either a byte or a longword
 * depending on alignment.  To be safe, assume it can copy at most
 * 64k bytes.  Don't make MAXBSIZE or MAXPHYS larger than 64k without
 * fixing this code!
 */
ENTRY(copyin)
	movl	sp@(12),d0		| get size
#ifdef MAPPEDCOPY
	.globl	_mappedcopysize,_mappedcopyin
	cmpl	_mappedcopysize,d0	| size >= mappedcopysize
	jcc	_mappedcopyin		| yes, go do it the new way
#endif
	movl	d2,sp@-			| scratch register
	movl	_curpcb,a0		| current pcb
	movl	#Lciflt,a0@(PCB_ONFAULT) | set up to catch faults
	tstl	d0			| check count
	jlt	Lciflt			| negative, error
	jeq	Lcidone			| zero, done
	movl	sp@(8),a0		| src address
	movl	sp@(12),a1		| dest address
	movl	a0,d2
	btst	#0,d2			| src address odd?
	jeq	Lcieven			| no, go check dest
	movsb	a0@+,d1			| yes, get a byte
	nop
	movb	d1,a1@+			| put a byte
	subql	#1,d0			| adjust count
	jeq	Lcidone			| exit if done
Lcieven:
	movl	a1,d2
	btst	#0,d2			| dest address odd?
	jne	Lcibloop		| yes, must copy by bytes
	movl	d0,d2			| no, get count
	lsrl	#2,d2			| convert to longwords
	jeq	Lcibloop		| no longwords, copy bytes
Lcilloop:
	movsl	a0@+,d1			| get a long
	nop
	movl	d1,a1@+			| put a long
	subql	#1,d2
	jne	Lcilloop		| til done
	andl	#3,d0			| what remains
	jeq	Lcidone			| all done
Lcibloop:
	movsb	a0@+,d1			| get a byte
	nop
	movb	d1,a1@+			| put a byte
	subql	#1,d0
	jne	Lcibloop		| til done
Lcidone:
	movl	_curpcb,a0		| current pcb
	clrl	a0@(PCB_ONFAULT) 	| clear fault catcher
	movl	sp@+,d2			| restore scratch reg
	rts
Lciflt:
	moveq	#EFAULT,d0		| got a fault
	jra	Lcidone

ENTRY(copyout)
	movl	sp@(12),d0		| get size
#ifdef MAPPEDCOPY
	.globl	_mappedcopysize,_mappedcopyout
	cmpl	_mappedcopysize,d0	| size >= mappedcopysize
	jcc	_mappedcopyout		| yes, go do it the new way
#endif
	movl	d2,sp@-			| scratch register
	movl	_curpcb,a0		| current pcb
	movl	#Lcoflt,a0@(PCB_ONFAULT) | catch faults
	tstl	d0			| check count
	jlt	Lcoflt			| negative, error
	jeq	Lcodone			| zero, done
	movl	sp@(8),a0		| src address
	movl	sp@(12),a1		| dest address
	movl	a0,d2
	btst	#0,d2			| src address odd?
	jeq	Lcoeven			| no, go check dest
	movb	a0@+,d1			| yes, get a byte
	movsb	d1,a1@+			| put a byte
	nop
	subql	#1,d0			| adjust count
	jeq	Lcodone			| exit if done
Lcoeven:
	movl	a1,d2
	btst	#0,d2			| dest address odd?
	jne	Lcobloop		| yes, must copy by bytes
	movl	d0,d2			| no, get count
	lsrl	#2,d2			| convert to longwords
	jeq	Lcobloop		| no longwords, copy bytes
Lcolloop:
	movl	a0@+,d1			| get a long
	movsl	d1,a1@+			| put a long
	nop
	subql	#1,d2
	jne	Lcolloop		| til done
	andl	#3,d0			| what remains
	jeq	Lcodone			| all done
Lcobloop:
	movb	a0@+,d1			| get a byte
	movsb	d1,a1@+			| put a byte
	nop
	subql	#1,d0
	jne	Lcobloop		| til done
Lcodone:
	movl	_curpcb,a0		| current pcb
	clrl	a0@(PCB_ONFAULT) 	| clear fault catcher
	movl	sp@+,d2			| restore scratch reg
	rts
Lcoflt:
	moveq	#EFAULT,d0		| got a fault
	jra	Lcodone

/*
 * non-local gotos
 */
ENTRY(setjmp)
	movl	sp@(4),a0	| savearea pointer
	moveml	#0xFCFC,a0@	| save d2-d7/a2-a7
	movl	sp@,a0@(48)	| and return address
	moveq	#0,d0		| return 0
	rts

ENTRY(longjmp)
	movl	sp@(4),a0
	moveml	a0@+,#0xFCFC
	movl	a0@,sp@
	moveq	#1,d0
	rts

/*
 * The following primitives manipulate the run queues.  _whichqs tells which
 * of the 32 queues _qs have processes in them.  Setrunqueue puts processes
 * into queues, Remrq removes them from queues.  The running process is on
 * no queue, other processes are on a queue related to p->p_priority, divided
 * by 4 actually to shrink the 0-127 range of priorities into the 32 available
 * queues.
 */

	.globl	_whichqs,_qs,_cnt,_panic
	.globl	_curproc,_want_resched

/*
 * Setrunqueue(p)
 *
 * Call should be made at spl6(), and p->p_stat should be SRUN
 */
ENTRY(setrunqueue)
	movl	sp@(4),a0
	tstl	a0@(P_BACK)
	jeq	Lset1
	movl	#Lset2,sp@-
	jbsr	_panic
Lset1:
	clrl	d0
	movb	a0@(P_PRIORITY),d0
	lsrb	#2,d0
	movl	_whichqs,d1
	bset	d0,d1
	movl	d1,_whichqs
	lslb	#3,d0
	addl	#_qs,d0
	movl	d0,a0@(P_FORW)
	movl	d0,a1
	movl	a1@(P_BACK),a0@(P_BACK)
	movl	a0,a1@(P_BACK)
	movl	a0@(P_BACK),a1
	movl	a0,a1@(P_FORW)
	rts

Lset2:
	.asciz	"setrunqueue"
	.even

/*
 * Remrq(p)
 *
 * Call should be made at spl6().
 */
ENTRY(remrq)
	movl	sp@(4),a0
	clrl	d0
	movb	a0@(P_PRIORITY),d0
	lsrb	#2,d0
	movl	_whichqs,d1
	bclr	d0,d1
	jne	Lrem1
	movl	#Lrem3,sp@-
	jbsr	_panic
Lrem1:
	movl	d1,_whichqs
	movl	a0@(P_FORW),a1
	movl	a0@(P_BACK),a1@(P_BACK)
	movl	a0@(P_BACK),a1
	movl	a0@(P_FORW),a1@(P_FORW)
	movl	#_qs,a1
	movl	d0,d1
	lslb	#3,d1
	addl	d1,a1
	cmpl	a1@(P_FORW),a1
	jeq	Lrem2
	movl	_whichqs,d1
	bset	d0,d1
	movl	d1,_whichqs
Lrem2:
	clrl	a0@(P_BACK)
	rts

Lrem3:
	.asciz	"remrq"
Lsw0:
	.asciz	"switch"
	.even

	.globl	_curpcb
	.globl	_masterpaddr	| XXX compatibility (debuggers)
	.data
_masterpaddr:			| XXX compatibility (debuggers)
_curpcb:
	.long	0
mdpflag:
	.byte	0		| copy of proc md_flags low byte
	.align	2
	.comm	nullpcb,SIZEOF_PCB
	.text

/*
 * At exit of a process, do a switch for the last time.
 * The mapping of the pcb at p->p_addr has already been deleted,
 * and the memory for the pcb+stack has been freed.
 * The ipl is high enough to prevent the memory from being reallocated.
 */
ENTRY(switch_exit)
	movl	#nullpcb,_curpcb	| save state into garbage pcb
	lea	tmpstk,sp		| goto a tmp stack
	jra	_cpu_switch

/*
 * When no processes are on the runq, Swtch branches to Idle
 * to wait for something to come ready.
 */
	.globl	idle
idle:
	stop	#PSL_LOWIPL
Idle:
	movw	#PSL_HIGHIPL,sr
	tstl	_whichqs
	jeq	idle
	movw	#PSL_LOWIPL,sr
	jra	Lsw1

Lbadsw:
	movl	#Lsw0,sp@-
	jbsr	_panic
	/*NOTREACHED*/

/*
 * cpu_switch()
 *
 * NOTE: On the mc68851 (318/319/330) we attempt to avoid flushing the
 * entire ATC.  The effort involved in selective flushing may not be
 * worth it, maybe we should just flush the whole thing?
 *
 * NOTE 2: With the new VM layout we now no longer know if an inactive
 * user's PTEs have been changed (formerly denoted by the SPTECHG p_flag
 * bit).  For now, we just always flush the full ATC.
 */
ENTRY(cpu_switch)
	movl	_curpcb,a0		| current pcb
	movw	sr,a0@(PCB_PS)		| save sr before changing ipl
#ifdef notyet
	movl	_curproc,sp@-		| remember last proc running
#endif
	clrl	_curproc
	addql	#1,_cnt+V_SWTCH

Lsw1:
	/*
	 * Find the highest-priority queue that isn't empty,
	 * then take the first proc from that queue.
	 */
	clrl	d0
	lea	_whichqs,a0
	movl	a0@,d1
Lswchk:
	btst	d0,d1
	jne	Lswfnd
	addqb	#1,d0
	cmpb	#32,d0
	jne	Lswchk
	jra	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