/*	$OpenBSD: gidt.S,v 1.15 1997/09/02 17:05:12 mickey Exp $	*/

/*
 * Copyright (c) 1997 Michael Shalayeff
 * All rights reserved.
 *
 * 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 Michael Shalayeff.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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.
 *
 */

	.file "gidt.S"

#include <machine/asm.h>
#define _LOCORE
#include <machine/trap.h>
#include <debug_md.h>
#undef _LOCORE
#include <assym.h>

#define addr32  .byte 0x67
#define data32  .byte 0x66

#define	SNULL	0x00
#define S32TEXT	0x08
#define	S32DATA	0x10
#define S16TEXT	0x18
#define	S16DATA	0x20

#ifdef GIDT_DEBUG
#define	gidt_debug0		; \
	movl	$0xb8000, %eax	; \
	movl	$0x47314730, (%eax)		; \
	movw	$S16DATA, %ax
#define	gidt_debug1		; \
	movl	%ax, %ds	; \
	movl	%ax, %es	; \
	data32			; \
	movl	$(0xb8000 - LINKADDR), %eax	; \
	data32			; \
	addr32			; \
	movl	$0x4f314f30, (%eax)
#define	gidt_debug2		; \
	data32			; \
	movl	$0xb8004, %eax	; \
	data32			; \
	addr32			; \
	movl	$0x47334732, (%eax)
#define	gidt_debug3		; \
	data32			; \
	movl	$0xb8004, %eax	; \
	data32			; \
	addr32			; \
	movl	$0x4f334f32, (%eax)
#define gidt_debug4		; \
	movl	$0xb8008, %eax	; \
	movl	$0x47344733, (%eax)
#else
#define gidt_debug0 /* gidt_debug0 */
#define gidt_debug1 /* gidt_debug1 */
#define gidt_debug2 /* gidt_debug2 */
#define gidt_debug3 /* gidt_debug3 */
#define gidt_debug4 /* gidt_debug4 */
#endif

#define prot2real						\
	gidt_debug0;						\
								\
	/* ljmp	$S16TEXT, $1f */;				\
	.byte	0xea;		/* Change to 16bit mode */	\
	.long	1f - LINKADDR;					\
	.word	S16TEXT;					\
1:								\
	gidt_debug1;						\
								\
	movl	%cr0, %eax;	/* disable pmmm */		\
	data32;							\
	andl 	$~CR0_PE, %eax;					\
	movl	%eax, %cr0;					\
								\
	/* ljmp	(LINKADDR >> 4), $1f */;			\
	.byte	0xea;		/* load real mode cs:ip */	\
	.word	1f;						\
	.word	(LINKADDR >> 4);				\
1:								\
	xorl	%eax, %eax;	/* setup: %ds, %es, %ss */	\
	movl	%ax, %ds;					\
	movl	%ax, %es;					\
	movl	%ax, %ss;					\
								\
	gidt_debug2;						\
								\
	addr32;							\
	data32;							\
	lidt	Idtr_real;	/* load idtr for real mode */

#define real2prot						\
	gidt_debug3;						\
								\
	addr32;							\
	data32;							\
	lgdt	Gdtr;		/* load the gdtr */		\
								\
	movl	%cr0, %eax;	/* enable pmmm */		\
	data32;							\
	orl	$CR0_PE, %eax;					\
	movl	%eax, %cr0;					\
								\
	data32;							\
	ljmp	$S32TEXT, $1f;   /* reload %cs flush pipeline */\
1:								\
	/* reload 32bit %ds, %ss, %es */			\
	movl	$S32DATA, %eax;					\
	movl	%ax, %ds;					\
	movl	%ax, %ss;					\
	movl	%ax, %es;					\
								\
	gidt_debug4;						\
								\
	/* load idtr for debugger and DOS/BIOS iface */		\
	lidt	Idtr;


	.globl	_C_LABEL(BIOS_regs)

	.text
	.globl	pmm_init
	.globl	__rtt

__rtt:
#ifdef GIDT_DEBUG
	movl	$0xb8000, %ebx
	movl	$0x4f514f51, (%ebx)
#endif
	movw	$0x1234, %ax
	movw	%ax, 0x472	# warm boot

	/* Try to use the KBD to reboot system */
	movb	$0xfe, %al
	outb	%al, $0x64

	movl	$0x5000, %ecx
1:	inb	$0x84, %al
	loop	1b

	movb	$0xfe, %al
	outb	%al, $0x64

#ifdef GIDT_DEBUG
	movl	$0xb8000, %ebx
	movl	$0x07310731, (%ebx)
#endif

	/* Try to cause a tripple fault... */
	lidt    Idtr_reset
	xorl	%eax, %eax
	divl	%eax, %eax

	/* Again... */
	int $0x8

	/* Again... */
	movl	$0, %esp	# segment violation
	ret

pmm_init:
	/* reload new gdt */
	lgdt	Gdtr
	ljmp	$8, $1f
1:	
	movw	$S32DATA, %ax
	movl	%ax, %ds
	movl	%ax, %ss
	movl	%ax, %es
	movl	%ax, %fs
	movl	%ax, %gs

	/* load idtr for interrupts */
	lidt	Idtr
	ret

#define IPROC(n)	X/**/n
#define IEMU(n)		IPROC(emu/**/n)
	.align 3
idt:
#define idte(e)	\
	.word IPROC(e), S32TEXT, (0x80|SDT_SYS386TGT) << 8, (LINKADDR >> 16)
		/* internal (0-31) */
	idte(de); idte(db); idte(nmi); idte(bp); idte(of); idte(br)
	idte(ud); idte(nm); idte(df);  idte(fo); idte(ts); idte(np)
	idte(ss); idte(gp); idte(pf);  idte(xx); idte(mf); idte(ac)
	idte(mc)
	idte(xx); idte(xx); idte(xx);  idte(xx); idte(xx); idte(xx)
	idte(xx); idte(xx); idte(xx);  idte(xx); idte(xx); idte(xx)
	idte(xx) 
		/*	Maskable interrupts (32-255) */
		/* BIOS entry points (32-63) */
		/* DOS entry points (64-80) */
#define idtb(b)	idte(emu/**/b)
	idtb(0);  idtb(1);  idtb(2);  idtb(3);  idtb(4);  idtb(5)
	idtb(6);  idtb(7);  idtb(8);  idtb(9);  idtb(10); idtb(11)
	idtb(12); idtb(13); idtb(14); idtb(15); idtb(16); idtb(17)
	idtb(18); idtb(19); idtb(20); idtb(21); idtb(22); idtb(23)
	idtb(24); idtb(25); idtb(26); idtb(27); idtb(28); idtb(29)
	idtb(30); idtb(31); idtb(32); idtb(33); idtb(34); idtb(35)
	idtb(36); idtb(37); idtb(38); idtb(39); idtb(40); idtb(41)
	idtb(42); idtb(43); idtb(44); idtb(45); idtb(46); idtb(47)
#undef idte
Idtr:	.word	. - idt - 1
	.long	idt
	.word	0

Idtr_real:	.word	1023
		.long	0
		.word	0

Idtr_reset:	.long	0, 0

gdt:
		/* 0x00 : null */
	.space	8
		/* 0x08 : flat code */
	.word	0xFFFF			# lolimit
	.word	0			# lobase
	.byte	0			# midbase
	.byte	SDT_MEMERAC | 0 | 0x80	# RXAC, dpl = 0, present
	.byte	0xf | 0 | 0x40 | 0x80	# hilimit, xx, 32bit, 4k granularity
	.byte	0			# hibase
		/* 0x10 : flat data */
	.word	0xFFFF			# lolimit
	.word	0			# lobase
	.byte	0			# midbase
	.byte	SDT_MEMRWA | 0 | 0x80	# RWA, dpl = 0, present
	.byte	0xf | 0 | 0x40 | 0x80	# hilimit, xx, 32bit, 4k granularity
	.byte	0			# hibase
		/* 0x18 : 16 bit code */
	.word	0xFFFF			# lolimit
	.word	(LINKADDR & 0xffff)	# lobase
	.byte	(LINKADDR >> 16) & 0xff	# midbase
	.byte	SDT_MEMERA | 0 | 0x80	# RXAC, dpl = 0, present
	.byte	0xf | 0 | 0 | 0		# hilimit, xx, 16bit, byte granularity
	.byte	(LINKADDR >> 20) & 0xff	# hibase
		/* 0x20 : 16 bit data */
	.word	0xFFFF			# lolimit
	.word	(LINKADDR & 0xffff)	# lobase
	.byte	(LINKADDR >> 16) & 0xff	# midbase
	.byte	SDT_MEMRWA | 0 | 0x80	# RXAC, dpl = 0, present
	.byte	0xf | 0 | 0 | 0		# hilimit, xx, 16bit, byte granularity
	.byte	(LINKADDR >> 20) & 0xff	# hibase

Gdtr:	.word	. - gdt - 1
	.long	gdt
	.word	0

#define IENTRY(name,type) \
IPROC(name): \
	pushl	$type ; \
	jmp	1f
#define IENTRY_ERR(name,err,type) \
IPROC(name): \
	pushl	$err ; \
	pushl	$type ; \
	jmp	1f

IPROC(xx):
	pushl	$1
	pushl	$T_RESERVED
	jmp	1f

IENTRY_ERR(de,0,T_DIVIDE)	/* #DE divide by zero */
IENTRY_ERR(db,0,T_TRCTRAP)	/* #DB debug */
IENTRY_ERR(nmi,0,T_NMI)		/* NMI */
IENTRY_ERR(bp,0,T_BPTFLT)	/* #BP breakpoint */
IENTRY_ERR(of,0,T_OFLOW)	/* #OF overflow */
IENTRY_ERR(br,0,T_BOUND)	/* #BR BOUND range exceeded */
IENTRY_ERR(ud,0,T_PRIVINFLT)	/* #UD invalid opcode */
IENTRY_ERR(nm,0,T_DNA)		/* #NM device not available */
IENTRY(df,T_DOUBLEFLT)		/* #DF double fault */
IENTRY_ERR(fo,0,T_FPOPFLT)	/* #FO coprocessor segment overrun */
IENTRY(ts,T_TSSFLT)		/* #TS innvalid TSS */
IENTRY(np,T_SEGNPFLT)		/* #NP segmant not present */
IENTRY(ss,T_STKFLT)		/* #SS stack fault */
IENTRY(gp,T_PROTFLT)		/* #GP general protection */
IENTRY(pf,T_PAGEFLT)		/* #PF page fault */
IENTRY_ERR(mf,0,T_ARITHTRAP)	/* #MF floating point error */
IENTRY(ac,T_ALIGNFLT)		/* #AC alignment check */
IENTRY(mc,T_MACHK)		/* #MC machine check */

	.globl	alltraps
1:	/* save on jumps */
	jmp	alltraps

#define	IEMUENT(n)	IEMU(n): pushl $n; jmp 1f

IEMUENT(0);  IEMUENT(1);  IEMUENT(2);  IEMUENT(3)
IEMUENT(4);  IEMUENT(5);  IEMUENT(6);  IEMUENT(7)
IEMUENT(8);  IEMUENT(9);  IEMUENT(10); IEMUENT(11)
IEMUENT(12); IEMUENT(13); IEMUENT(14); IEMUENT(15)
IEMUENT(16); IEMUENT(17); IEMUENT(18); IEMUENT(19)
IEMUENT(20); IEMUENT(21); IEMUENT(22); IEMUENT(23)
IEMUENT(24); IEMUENT(25); IEMUENT(26); IEMUENT(27)
IEMUENT(28); IEMUENT(29); IEMUENT(30); IEMUENT(31)
1:	jmp	EMUh	/* redirect for short jumps */
IEMUENT(32); IEMUENT(33); IEMUENT(34); IEMUENT(35)
IEMUENT(36); IEMUENT(37); IEMUENT(38); IEMUENT(39)
IEMUENT(40); IEMUENT(41); IEMUENT(42); IEMUENT(43)
IEMUENT(44); IEMUENT(45); IEMUENT(46); IEMUENT(47)
1:	jmp	EMUh

/*
 * entry point for BIOS real-mode interface
 * all the magic for real-prot mode switching is here
 *
 * Call:	%eax, %ecx, %edx, %ebx, %ebp, %esi, %edi, %es, %ds
 * Return:	%eax, %edx, %ecx, %eflags (as returned from BIOS)
 *
 */
EMUh:
	/* save %eax */
	movl	%eax, 3f
	popl	%eax

	pushal
	pushl	%ds
	pushl	%es
	pushl	%fs
	pushl	%gs

	/* save BIOS int vector */
	movb	%al, intno

	prot2real

	pushl	%ds

	addr32
	movl	_C_LABEL(BIOS_regs)+(biosr_es), %eax
	movl	%ax, %es
	addr32
	movl	_C_LABEL(BIOS_regs)+(biosr_ds), %eax
	movl	%ax, %ds

	data32
	# movl	Leax, %eax
	.byte	0xb8
3:	.long	0x90909090	/* restore %eax */

	sti
	int	$0
intno	= . - 1
	cli

	popl	%ds

	addr32
	data32
	movl	%ebx, _C_LABEL(BIOS_regs)+(biosr_bx)
	movl	%es, %bx
	addr32
	movl	%bx, _C_LABEL(BIOS_regs)+(biosr_es)
	movb	%ah, %bh	/* save flags to return to caller */
	lahf
	xchgb	%ah, %bh

	addr32
	data32
	movl	%eax, 2f	/* save %eax */

	real2prot

	# movl	Leax, %eax
	.byte	0xb8
2:	.long	0x90909090	/* eax */

	/* pass BIOS return values back to caller */
	movl	%eax, 0xb*4(%esp)
	movl	%ecx, 0xa*4(%esp)
	movl	%edx, 0x9*4(%esp)
	movb	%bh , 0xe*4(%esp)

	/* save registers into save area */
	movl	%eax, _C_LABEL(BIOS_regs)+biosr_ax
	movl	%ecx, _C_LABEL(BIOS_regs)+biosr_cx
	movl	%edx, _C_LABEL(BIOS_regs)+biosr_dx
	movl	%ebp, _C_LABEL(BIOS_regs)+biosr_bp
	movl	%esi, _C_LABEL(BIOS_regs)+biosr_si
	movl	%edi, _C_LABEL(BIOS_regs)+biosr_di

	popl	%gs
	popl	%fs
	popl	%es
	popl	%ds
	popal
	iret