locore.s

早期freebsd实现

/*-
 * Copyright (c) 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * William Jolitz.
 *
 * 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: @(#)locore.s	7.3 (Berkeley) 5/13/91
 *	from NetBSD: Id: locore.s,v 1.12 1993/05/27 16:44:13 cgd Exp
 *
 *      @(#)locore.s	8.3 (Berkeley) 9/23/93
 */


/*
 * locore.s:	4BSD machine support for the Intel 386
 *		Preliminary version
 *		Written by William F. Jolitz, 386BSD Project
 */

#include "assym.s"
#include "machine/psl.h"
#include "machine/pte.h"

#include "errno.h"

#include "machine/trap.h"

#include "machine/specialreg.h"

#ifdef cgd_notdef
#include "machine/cputypes.h"
#endif

#define	KDSEL		0x10

/*
 * Note: This version greatly munged to avoid various assembler errors
 * that may be fixed in newer versions of gas. Perhaps newer versions
 * will have more pleasant appearance.
 */

	.set	IDXSHIFT,10
	.set	SYSTEM,0xFE000000	# virtual address of system start
	/*note: gas copys sign bit (e.g. arithmetic >>), can't do SYSTEM>>22! */
	.set	SYSPDROFF,0x3F8		# Page dir index of System Base

#define	NOP	inb $0x84, %al ; inb $0x84, %al 
#define	ALIGN32	.align 2	/* 2^2  = 4 */

/*
 * PTmap is recursive pagemap at top of virtual address space.
 * Within PTmap, the page directory can be found (third indirection).
 */
	.set	PDRPDROFF,0x3F7		# Page dir index of Page dir
	.globl	_PTmap, _PTD, _PTDpde, _Sysmap
	.set	_PTmap,0xFDC00000
	.set	_PTD,0xFDFF7000
	.set	_Sysmap,0xFDFF8000
	.set	_PTDpde,0xFDFF7000+4*PDRPDROFF

/*
 * APTmap, APTD is the alternate recursive pagemap.
 * It's used when modifying another process's page tables.
 */
	.set	APDRPDROFF,0x3FE		# Page dir index of Page dir
	.globl	_APTmap, _APTD, _APTDpde
	.set	_APTmap,0xFF800000
	.set	_APTD,0xFFBFE000
	.set	_APTDpde,0xFDFF7000+4*APDRPDROFF

/*
 * Access to each processes kernel stack is via a region of
 * per-process address space (at the beginning), immediatly above
 * the user process stack.
 */
	.set	_kstack, USRSTACK
	.globl	_kstack
	.set	PPDROFF,0x3F6
	.set	PPTEOFF,0x400-UPAGES	# 0x3FE

#define	ENTRY(name) \
	.globl _/**/name; _/**/name:
#define	ALTENTRY(name) \
	.globl _/**/name; _/**/name:

/*
 * Initialization
 */
	.data
	.globl	_cpu,_cold,_boothowto,_bootdev,_cyloffset,_atdevbase,_atdevphys
_cpu:	.long	0		# are we 386, 386sx, or 486
_cold:	.long	1		# cold till we are not
_atdevbase:	.long	0	# location of start of iomem in virtual
_atdevphys:	.long	0	# location of device mapping ptes (phys)

	.globl	_IdlePTD, _KPTphys
_IdlePTD:	.long	0
_KPTphys:	.long	0

	.space 512
tmpstk:
	.text
	.globl	start
start:	movw	$0x1234,%ax
	movw	%ax,0x472	# warm boot
	jmp	1f
	.space	0x500		# skip over warm boot shit

	/*
	 * pass parameters on stack (howto, bootdev, unit, cyloffset)
	 * note: 0(%esp) is return address of boot
	 * ( if we want to hold onto /boot, it's physical %esp up to _end)
	 */

 1:	movl	4(%esp),%eax
	movl	%eax,_boothowto-SYSTEM
	movl	8(%esp),%eax
	movl	%eax,_bootdev-SYSTEM
	movl	12(%esp),%eax
	movl	%eax, _cyloffset-SYSTEM

#ifdef cgd_notdef
	/* find out our CPU type. */
        pushfl
        popl    %eax
        movl    %eax, %ecx
        xorl    $0x40000, %eax
        pushl   %eax
        popfl
        pushfl
        popl    %eax
        xorl    %ecx, %eax
        shrl    $18, %eax
        andl    $1, %eax
        push    %ecx
        popfl
      
        cmpl    $0, %eax
        jne     1f
        movl    $CPU_386, _cpu-SYSTEM
	jmp	2f
1:      movl    $CPU_486, _cpu-SYSTEM
2:
#endif

#ifdef garbage
	/* count up memory */

	xorl	%eax,%eax		# start with base memory at 0x0
	#movl	$ 0xA0000/NBPG,%ecx	# look every 4K up to 640K
	movl	$ 0xA0,%ecx		# look every 4K up to 640K
1:	movl	0(%eax),%ebx		# save location to check
	movl	$0xa55a5aa5,0(%eax)	# write test pattern
	/* flush stupid cache here! (with bcopy (0,0,512*1024) ) */
	cmpl	$0xa55a5aa5,0(%eax)	# does not check yet for rollover
	jne	2f
	movl	%ebx,0(%eax)		# restore memory
	addl	$ NBPG,%eax
	loop	1b
2:	shrl	$12,%eax
	movl	%eax,_Maxmem-SYSTEM

	movl	$0x100000,%eax		# next, talley remaining memory
	#movl	$((0xFFF000-0x100000)/NBPG),%ecx
	movl	$(0xFFF-0x100),%ecx
1:	movl	0(%eax),%ebx		# save location to check
	movl	$0xa55a5aa5,0(%eax)	# write test pattern
	cmpl	$0xa55a5aa5,0(%eax)	# does not check yet for rollover
	jne	2f
	movl	%ebx,0(%eax)		# restore memory
	addl	$ NBPG,%eax
	loop	1b
2:	shrl	$12,%eax
	movl	%eax,_Maxmem-SYSTEM
#endif

/* find end of kernel image */
	movl	$_end-SYSTEM,%ecx
	addl	$ NBPG-1,%ecx
	andl	$~(NBPG-1),%ecx
	movl	%ecx,%esi

/* clear bss and memory for bootstrap pagetables. */
	movl	$_edata-SYSTEM,%edi
	subl	%edi,%ecx
	addl	$(UPAGES+5)*NBPG,%ecx
/*
 * Virtual address space of kernel:
 *
 *	text | data | bss | page dir | proc0 kernel stack | usr stk map | Sysmap
 *			     0               1       2       3             4
 */
	xorl	%eax,%eax	# pattern
	cld
	rep
	stosb

	movl	%esi,_IdlePTD-SYSTEM /*physical address of Idle Address space */
	movl	$ tmpstk-SYSTEM,%esp	# bootstrap stack end location

#define	fillkpt		\
1:	movl	%eax,0(%ebx)	; \
	addl	$ NBPG,%eax	; /* increment physical address */ \
	addl	$4,%ebx		; /* next pte */ \
	loop	1b		;

/*
 * Map Kernel
 * N.B. don't bother with making kernel text RO, as 386
 * ignores R/W AND U/S bits on kernel access (only v works) !
 *
 * First step - build page tables
 */
	movl	%esi,%ecx		# this much memory,
	shrl	$ PGSHIFT,%ecx		# for this many pte s
	addl	$ UPAGES+4,%ecx		# including our early context
	movl	$ PG_V,%eax		#  having these bits set,
	lea	(4*NBPG)(%esi),%ebx	#   physical address of KPT in proc 0,
	movl	%ebx,_KPTphys-SYSTEM	#    in the kernel page table,
	fillkpt

/* map I/O memory map */

	movl	$0x100-0xa0,%ecx	# for this many pte s,
	movl	$(0xa0000|PG_V|PG_UW),%eax # having these bits set,(perhaps URW?) XXX 06 Aug 92
	movl	%ebx,_atdevphys-SYSTEM	#   remember phys addr of ptes
	fillkpt

 /* map proc 0's kernel stack into user page table page */

	movl	$ UPAGES,%ecx		# for this many pte s,
	lea	(1*NBPG)(%esi),%eax	# physical address in proc 0
	lea	(SYSTEM)(%eax),%edx
	movl	%edx,_proc0paddr-SYSTEM  # remember VA for 0th process init
	orl	$ PG_V|PG_URKW,%eax	#  having these bits set,
	lea	(3*NBPG)(%esi),%ebx	# physical address of stack pt in proc 0
	addl	$(PPTEOFF*4),%ebx
	fillkpt

/*
 * Construct a page table directory
 * (of page directory elements - pde's)
 */
	/* install a pde for temporary double map of bottom of VA */
	lea	(4*NBPG)(%esi),%eax	# physical address of kernel page table
	orl     $ PG_V|PG_UW,%eax	# pde entry is valid XXX 06 Aug 92
	movl	%eax,(%esi)		# which is where temp maps!

	/* kernel pde's */
	movl	$ 3,%ecx		# for this many pde s,
	lea	(SYSPDROFF*4)(%esi), %ebx	# offset of pde for kernel
	fillkpt

	/* install a pde recursively mapping page directory as a page table! */
	movl	%esi,%eax		# phys address of ptd in proc 0
	orl	$ PG_V|PG_UW,%eax	# pde entry is valid XXX 06 Aug 92
	movl	%eax, PDRPDROFF*4(%esi)	# which is where PTmap maps!

	/* install a pde to map kernel stack for proc 0 */
	lea	(3*NBPG)(%esi),%eax	# physical address of pt in proc 0
	orl	$ PG_V,%eax		# pde entry is valid
	movl	%eax,PPDROFF*4(%esi)	# which is where kernel stack maps!

	/* load base of page directory, and enable mapping */
	movl	%esi,%eax		# phys address of ptd in proc 0
 	orl	$ I386_CR3PAT,%eax
	movl	%eax,%cr3		# load ptd addr into mmu
	movl	%cr0,%eax		# get control word
	orl	$0x80000001,%eax	# and let s page!
	movl	%eax,%cr0		# NOW!

	pushl	$begin				# jump to high mem!
	ret

begin: /* now running relocated at SYSTEM where the system is linked to run */

	.globl _Crtat
	movl	_Crtat,%eax
	subl	$0xfe0a0000,%eax
	movl	_atdevphys,%edx	# get pte PA
	subl	_KPTphys,%edx	# remove base of ptes, now have phys offset
	shll	$ PGSHIFT-2,%edx  # corresponding to virt offset
	addl	$ SYSTEM,%edx	# add virtual base
	movl	%edx, _atdevbase
	addl	%eax,%edx
	movl	%edx,_Crtat

	/* set up bootstrap stack */
	movl	$ _kstack+UPAGES*NBPG-4*12,%esp	# bootstrap stack end location
	xorl	%eax,%eax		# mark end of frames
	movl	%eax,%ebp
	movl	_proc0paddr, %eax
	movl	%esi, PCB_CR3(%eax)

	lea	7*NBPG(%esi),%esi	# skip past stack.
	pushl	%esi
	
	call	_init386		# wire 386 chip for unix operation
	
	movl	$0,_PTD
	call 	_main
	popl	%esi

	.globl	__ucodesel,__udatasel
	movzwl	__ucodesel,%eax
	movzwl	__udatasel,%ecx
	# build outer stack frame
	pushl	%ecx		# user ss
	pushl	$ USRSTACK	# user esp
	pushl	%eax		# user cs
	pushl	$0		# user ip
	movw	%cx,%ds
	movw	%cx,%es
	movw	%ax,%fs		# double map cs to fs
	movw	%cx,%gs		# and ds to gs
	lret	# goto user!

	pushl	$lretmsg1	/* "should never get here!" */
	call	_panic
lretmsg1:
	.asciz	"lret: toinit\n"


	.set	exec,59
	.set	exit,1
	.globl	_icode
	.globl	_szicode

#define	LCALL(x,y)	.byte 0x9a ; .long y; .word x
/*
 * Icode is copied out to process 1 to exec /etc/init.
 * If the exec fails, process 1 exits.
 */
_icode:
	# pushl	$argv-_icode	# gas fucks up again
	movl	$argv,%eax
	subl	$_icode,%eax
	pushl	%eax

	# pushl	$init-_icode
	movl	$init,%eax
	subl	$_icode,%eax
	pushl	%eax
	pushl	%eax	# dummy out rta

	movl	%esp,%ebp
	movl	$exec,%eax
	LCALL(0x7,0x0)
	pushl	%eax
	movl	$exit,%eax
	pushl	%eax	# dummy out rta
	LCALL(0x7,0x0)

init:
	.asciz	"/sbin/init"
	.align	2
argv:
	.long	init+6-_icode		# argv[0] = "init" ("/sbin/init" + 6)
	.long	eicode-_icode		# argv[1] follows icode after copyout
	.long	0
eicode:

_szicode:
	.long	_szicode-_icode

	.globl	_sigcode,_szsigcode
_sigcode:
	movl	12(%esp),%eax	# unsure if call will dec stack 1st
	call	%eax
	xorl	%eax,%eax	# smaller movl $103,%eax
	movb	$103,%al	# sigreturn()
	LCALL(0x7,0)		# enter kernel with args on stack
	hlt			# never gets here

_szsigcode:
	.long	_szsigcode-_sigcode

	/*
	 * Support routines for GCC
	 */
	.globl ___udivsi3
	ALIGN32
___udivsi3:
	movl 4(%esp),%eax
	xorl %edx,%edx
	divl 8(%esp)
	ret

	.globl ___divsi3
	ALIGN32
___divsi3:
	movl 4(%esp),%eax
	#xorl %edx,%edx		/* not needed - cltd sign extends into %edx */
	cltd
	idivl 8(%esp)
	ret

	/*
	 * I/O bus instructions via C
	 */
	.globl	_inb
	ALIGN32
_inb:	movl	4(%esp),%edx
	subl	%eax,%eax	# clr eax
	NOP
	inb	%dx,%al
	ret


	.globl	_inw
	ALIGN32
_inw:	movl	4(%esp),%edx
	subl	%eax,%eax	# clr eax
	NOP
	inw	%dx,%ax
	ret


	.globl	_rtcin
	ALIGN32
_rtcin:	movl	4(%esp),%eax
	outb	%al,$0x70
	subl	%eax,%eax	# clr eax
	inb	$0x71,%al	# Compaq SystemPro 
	ret

	.globl	_outb
	ALIGN32
_outb:	movl	4(%esp),%edx
	NOP
	movl	8(%esp),%eax
	outb	%al,%dx
	NOP
	ret

	.globl	_outw
	ALIGN32
_outw:	movl	4(%esp),%edx
	NOP
	movl	8(%esp),%eax
	outw	%ax,%dx
	NOP
	ret

	/*
	 * void bzero(void *base, u_int cnt)
	 */

	.globl _bzero
	ALIGN32
_bzero:
	pushl	%edi
	movl	8(%esp),%edi
	movl	12(%esp),%ecx
	xorl	%eax,%eax
	shrl	$2,%ecx	
	cld
	rep
	stosl
	movl	12(%esp),%ecx
	andl	$3,%ecx
	rep
	stosb
	popl	%edi
	ret

	/*
	 * fillw (pat,base,cnt)
	 */

	.globl _fillw
	ALIGN32
_fillw:
	pushl	%edi
	movl	8(%esp),%eax
	movl	12(%esp),%edi
	movw	%ax, %cx
	rorl	$16, %eax
	movw	%cx, %ax
	cld
	movl	16(%esp),%ecx
	shrl	%ecx
	rep
	stosl
	movl	16(%esp),%ecx
	andl	$1, %ecx
	rep
	stosw
	popl	%edi
	ret

	.globl _bcopyb
	ALIGN32
_bcopyb:
	pushl	%esi
	pushl	%edi
	movl	12(%esp),%esi
	movl	16(%esp),%edi
	movl	20(%esp),%ecx
	cld
	rep
	movsb
	popl	%edi
	popl	%esi
	xorl	%eax,%eax
	ret

	/*
	 * (ov)bcopy (src,dst,cnt)
	 *  [e-mail]     (Wolfgang Solfrank, TooLs GmbH) [phone]
	 */

	.globl	_bcopy,_ovbcopy
	ALIGN32
_ovbcopy:
_bcopy:
	pushl	%esi
	pushl	%edi
	movl	12(%esp),%esi
	movl	16(%esp),%edi
	movl	20(%esp),%ecx
	cmpl	%esi,%edi	/* potentially overlapping? */
	jnb	1f
	cld			/* nope, copy forwards. */
	shrl	$2,%ecx		/* copy by words */
	rep
	movsl
	movl	20(%esp),%ecx
	andl	$3,%ecx		/* any bytes left? */
	rep
	movsb
	popl	%edi
	popl	%esi
	xorl	%eax,%eax
	ret
	ALIGN32
1:
	addl	%ecx,%edi	/* copy backwards. */
	addl	%ecx,%esi
	std