locore.s

早期freebsd实现

/*
 * Copyright (c) 1988 University of Utah.
 * Copyright (c) 1992 OMRON Corporation.
 * 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 $Hdr: locore.s 1.62 92/01/20$
 * from: hp300/hp300/locore.s	8.5 (Berkeley) 11/14/93
 *
 *	@(#)locore.s	8.4 (Berkeley) 12/6/93
 */

/*
 * STACKCHECK enables two types of kernel stack checking:
 *	1. stack "overflow".  On every clock interrupt we ensure that
 *	   the current kernel stack has not grown into the user struct
 *	   page, i.e. size exceeded UPAGES-1 pages.
 *	2. stack "underflow".  Before every rte to user mode we ensure
 *	   that we will be exactly at the base of the stack after the
 *	   exception frame has been popped.
 * Both checks are performed at splclock since they operate on the
 * global temporary stack.
 */
/* #define	STACKCHECK */

#include "assym.s"
#include <luna68k/luna68k/vectors.s>

/*
 * Temporary stack for a variety of purposes.
 * Try and make this the first thing is the data segment so it
 * is page aligned.  Note that if we overflow here, we run into
 * our text segment.
 */
	.data
	.space	NBPG
tmpstk:

	.text
/*
 * This is where we wind up if the kernel jumps to location 0.
 * (i.e. a bogus PC)  This is known to immediately follow the vector
 * table and is hence at 0x400 (see reset vector in vectors.s).
 */
	.globl	_panic
	pea	Ljmp0panic
	jbsr	_panic
	/* NOTREACHED */
Ljmp0panic:
	.asciz	"kernel jump to zero"
	.even

/*
 * Do a dump.
 * Called by auto-restart.
 */
	.globl	_dumpsys
	.globl	_doadump
_doadump:
	jbsr	_dumpsys
	jbsr	_doboot
	/*NOTREACHED*/

/*
 * Trap/interrupt vector routines
 */ 

	.globl	_trap, _nofault, _longjmp
_buserr:
	tstl	_nofault		| device probe?
	jeq	Lberr			| no, handle as usual
	movl	_nofault,sp@-		| yes,
	jbsr	_longjmp		|  longjmp(nofault)
Lberr:
#if defined(LUNA2)
	cmpl	#-2,_mmutype		| 68040?
	jne	_addrerr		| no, skip
	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@(12),d0		| grab SSW
	movl	a1@(20),d1		| and fault VA
	btst	#11,d0			| check for mis-aligned access
	jeq	Lberr2			| no, skip
	addl	#3,d1			| yes, get into next page
	andl	#PG_FRAME,d1		| and truncate
Lberr2:
	movl	d1,sp@-			| push fault VA
	movl	d0,sp@-			| and padded SSW
	btst	#10,d0			| ATC bit set?
	jeq	Lisberr			| no, must be a real bus error
	movc	dfc,d1			| yes, get MMU fault
	movc	d0,dfc			| store faulting function code
	movl	sp@(4),a0		| get faulting address
	.word	0xf568			| ptestr a0@
	movc	d1,dfc
	.long	0x4e7a0805		| movc mmusr,d0
	movw	d0,sp@			| save (ONLY LOW 16 BITS!)
	jra	Lismerr
#endif
_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
#if defined(LUNA2)
	cmpl	#-2,_mmutype		| 68040?
	jne	Lbenot040		| no, skip
	movl	a1@(8),sp@-		| yes, push fault address
	clrl	sp@-			| no SSW for address fault
	jra	Lisaerr			| go deal with it
Lbenot040:
#endif
	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
	movl	d1,a0			| fault address
	ptestr	#1,a0@,#7		| do a table search
	pmove	psr,sp@			| save result
	btst	#7,sp@			| bus error bit set?
	jeq	Lismerr			| no, must be MMU fault
	clrw	sp@			| yes, re-clear pad word
	jra	Lisberr			| and process as normal bus error
Lismerr:
	movl	#T_MMUFLT,sp@-		| show that we are an MMU fault
	jra	Ltrapnstkadj		| and deal with it
Lisaerr:
	movl	#T_ADDRERR,sp@-		| mark address error
	jra	Ltrapnstkadj		| and deal with it
Lisberr:
	movl	#T_BUSERR,sp@-		| mark bus error
Ltrapnstkadj:
	jbsr	_trap			| handle the error
	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	Lstkadj			| yes, go to it
	moveml	sp@+,#0x7FFF		| no, restore most user regs
	addql	#8,sp			| toss SSP and stkadj
	jra	rei			| all done
Lstkadj:
	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
	jra	rei			| all done

/*
 * FP exceptions.
 */
_fpfline:
#if defined(LUNA2)
	cmpw	#0x202c,sp@(6)		| format type 2?
	jne	_illinst		| no, not an FP emulation
#ifdef HPFPLIB
	.globl fpsp_unimp
	jmp	fpsp_unimp		| yes, go handle it
#else
	clrl	sp@-			| stack adjust count
	moveml	#0xFFFF,sp@-		| save registers
	moveq	#T_FPEMULI,d0		| denote as FP emulation trap
	jra	fault			| do it
#endif
#else
	jra	_illinst
#endif

_fpunsupp:
#if defined(LUNA2)
	cmpl	#-2,_mmutype		| 68040?
	jne	_illinst		| no, treat as illinst
#ifdef HPFPLIB
	.globl	fpsp_unsupp
	jmp	fpsp_unsupp		| yes, go handle it
#else
	clrl	sp@-			| stack adjust count
	moveml	#0xFFFF,sp@-		| save registers
	moveq	#T_FPEMULD,d0		| denote as FP emulation trap
	jra	fault			| do it
#endif
#else
	jra	_illinst
#endif

/*
 * 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.
 */
_fpfault:
#ifdef FPCOPROC
	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	_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	Ltrapnstkadj	| call trap and deal with stack cleanup
#else
	jra	_badtrap	| treat as an unexpected trap
#endif

#ifdef HPFPLIB
/*
 * We wind up here from the 040 FP emulation library after
 * the exception has been processed.
 */
	.globl	_fault
_fault:
	subql	#4,sp		| space for rts addr
	movl	d0,sp@-		| scratch register
	movw	sp@(14),d0	| get vector offset
	andl	#0xFFF,d0	| mask out frame type and clear high word
	cmpl	#0x100,d0	| HP-UX style reschedule trap?
	jne	Lfault1		| no, skip
	movl	sp@+,d0		| restore scratch register
	addql	#4,sp		| pop space
	jra	Lrei1		| go do AST
Lfault1:
	cmpl	#0xC0,d0	| FP exception?
	jlt	Lfault2		| no, skip
	movl	sp@+,d0		| yes, backoff
	addql	#4,sp		|  and prepare for normal trap frame
	jra	_fpfault	| go to it
Lfault2:
	addl	#Lvectab,d0	| convert to vector table offset
	exg	d0,a0
	movl	a0@,sp@(4) 	| get exception vector and save for rts
	exg	d0,a0
	movl	sp@+,d0		|   scratch registers
	rts			| return to handler from vectab
#endif

/*
 * Coprocessor and format errors can generate mid-instruction stack
 * frames and cause signal delivery hence we need to check for potential
 * stack adjustment.
 */
_coperr:
	clrl	sp@-		| stack adjust count
	moveml	#0xFFFF,sp@-
	movl	usp,a0		| get and save
	movl	a0,sp@(FR_SP)	|   the user stack pointer
	clrl	sp@-		| no VA arg
	clrl	sp@-		| or code arg
	movl	#T_COPERR,sp@-	| push trap type
	jra	Ltrapnstkadj	| call trap and deal with stack adjustments

_fmterr:
	clrl	sp@-		| stack adjust count
	moveml	#0xFFFF,sp@-
	movl	usp,a0		| get and save
	movl	a0,sp@(FR_SP)	|   the user stack pointer
	clrl	sp@-		| no VA arg
	clrl	sp@-		| or code arg
	movl	#T_FMTERR,sp@-	| push trap type
	jra	Ltrapnstkadj	| call trap and deal with stack adjustments

/*
 * Other exceptions only cause four and six word stack frame and require
 * no post-trap stack adjustment.
 */
_illinst:
	clrl	sp@-
	moveml	#0xFFFF,sp@-
	moveq	#T_ILLINST,d0
	jra	fault

_zerodiv:
	clrl	sp@-
	moveml	#0xFFFF,sp@-
	moveq	#T_ZERODIV,d0
	jra	fault

_chkinst:
	clrl	sp@-
	moveml	#0xFFFF,sp@-
	moveq	#T_CHKINST,d0
	jra	fault

_trapvinst:
	clrl	sp@-
	moveml	#0xFFFF,sp@-
	moveq	#T_TRAPVINST,d0
	jra	fault

_privinst:
	clrl	sp@-
	moveml	#0xFFFF,sp@-
	moveq	#T_PRIVINST,d0
	jra	fault

	.globl	fault
fault:
	movl	usp,a0			| get and save
	movl	a0,sp@(FR_SP)		|   the user stack pointer
	clrl	sp@-			| no VA arg
	clrl	sp@-			| or code arg
	movl	d0,sp@-			| push trap type
	jbsr	_trap			| handle trap
	lea	sp@(12),sp		| pop value args
	movl	sp@(FR_SP),a0		| restore
	movl	a0,usp			|   user SP
	moveml	sp@+,#0x7FFF		| restore most user regs
	addql	#8,sp			| pop SP and stack adjust
	jra	rei			| all done

	.globl	_straytrap
_badtrap:
	moveml	#0xC0C0,sp@-		| save scratch regs
	movw	sp@(22),sp@-		| push exception vector info
	clrw	sp@-
	movl	sp@(22),sp@-		| and PC
	jbsr	_straytrap		| report
	addql	#8,sp			| pop args
	moveml	sp@+,#0x0303		| restore regs
	jra	rei			| all done

	.globl	_syscall
_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	_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	rei			| all done

/*
 * trap1 is sigreturn and trap2 is breakpoint.
 */
_trap1:
	jra	sigreturn		| trap1 is sigreturn

_trap2:
	jra	_trace			| trap2 is breakpoint

/*
 * Trap 12 is the entry point for the cachectl "syscall" (both HPUX & BSD)
 *	cachectl(command, addr, length)
 * command in d0, addr in a1, length in d1
 */
	.globl	_cachectl
_trap12:
	movl	d1,sp@-			| push length
	movl	a1,sp@-			| push addr
	movl	d0,sp@-			| push command
	jbsr	_cachectl		| do it
	lea	sp@(12),sp		| pop args
	jra	rei			| all done

/*
 * Trap 15 is used for:
 *	- KGDB traps
 *	- trace traps for SUN binaries (not fully supported yet)
 * We just pass it on and let trap() sort it all out
 */
_trap15:
	clrl	sp@-
	moveml	#0xFFFF,sp@-
#ifdef KGDB
	moveq	#T_TRAP15,d0
	movw	sp@(FR_HW),d1		| get PSW
	andw	#PSL_S,d1		| from user mode?
	jeq	fault			| yes, just a regular fault
	movl	d0,sp@-
	.globl	_kgdb_trap_glue
	jbsr	_kgdb_trap_glue		| returns if no debugger
	addl	#4,sp
#endif
	moveq	#T_TRAP15,d0
	jra	fault

/*
 * Hit a breakpoint (trap 1 or 2) instruction.
 * Push the code and treat as a normal fault.
 */
_trace:
	clrl	sp@-
	moveml	#0xFFFF,sp@-
#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)