mirror of
https://git.FreeBSD.org/src.git
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886b0df400
Submitted by: DI. Christian Gusenbauer <cg@fimp01.fim.uni-linz.ac.at>
596 lines
14 KiB
C
596 lines
14 KiB
C
/*
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* protmod.c Protected Mode Utilities
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*
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* (C) 1994 by Christian Gusenbauer (cg@fimp01.fim.uni-linz.ac.at)
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* All Rights Reserved.
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*
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* Permission to use, copy, modify and distribute this software and its
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* documentation is hereby granted, provided that both the copyright
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* notice and this permission notice appear in all copies of the
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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*
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* I ALLOW YOU USE OF THIS SOFTWARE IN ITS "AS IS" CONDITION. I DISCLAIM
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* ANY LIABILITY OF ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE
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* USE OF THIS SOFTWARE.
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*
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <dos.h>
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#include <memory.h>
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#include <process.h>
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#include "boot.h"
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#include "bootinfo.h"
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#include "protmod.h"
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#define data32 _emit 0x66
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#define addr32 _emit 0x67
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#define SEG(a) ((unsigned int)(((long)(a))>>16l))
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#define OFF(a) ((unsigned int)((long)(a)))
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#define ptr2lin(a) ((unsigned long)(SEG(a)*0x10l+(long)OFF(a)))
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typedef struct {
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unsigned short limit; /* Segment limit */
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unsigned long addr:24; /* address */
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unsigned long rights:8; /* access rights */
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unsigned short reserved; /* reserved on 80286 */
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} DTENTRY;
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struct dtr {
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unsigned short limit;
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unsigned long base;
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};
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struct {
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unsigned long cr3;
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unsigned long GdtrAddress;
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unsigned long IdtrAddress;
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unsigned short LDTR;
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unsigned short TR;
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unsigned long EIP;
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unsigned short CS;
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} VCPI;
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static DTENTRY gdt[] =
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{
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{ 0, 0, 0, 0 }, /* Dummy */
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{ 0, 0, 0, 0 }, /* GDT itself */
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{ 0, 0, 0, 0 }, /* FROM */
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{ 0, 0, 0, 0 }, /* TO */
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{ 0, 0, 0, 0 }, /* BIOS CS */
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{ 0, 0, 0, 0 } /* SS */
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};
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static DTENTRY gdt2[] =
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{
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{ 0, 0, 0, 0 }, /* Dummy */
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{ 0, 0, 0, 0 }, /* GDT itself */
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{ 0, 0, 0, 0 }, /* IDT */
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{ 0, 0, 0, 0 }, /* DS */
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{ 0, 0, 0, 0 }, /* ES */
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{ 0, 0, 0, 0 }, /* SS */
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{ 0, 0, 0, 0 }, /* CS */
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{ 0, 0, 0, 0 }, /* BIOS CS, uninitialized */
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{ 0, 0, 0, 0 } /* VCPI: TSS */
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};
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static DTENTRY FreeBSDGdt[] = {
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{ 0x0000, 0, 0x00, 0x0000 }, /* 0: empty */
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{ 0xffff, 0, 0x9f, 0x00cf }, /* 1: kernel code */
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{ 0xffff, 0, 0x93, 0x00cf }, /* 2: kernel data */
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{ 0xffff, 0, 0x9e, 0x0040 }, /* 3: boot code */
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{ 0xffff, 0, 0x92, 0x0040 }, /* 4: boot data */
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{ 0xffff, 0, 0x9e, 0x0000 }, /* 5: 16bit boot code */
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};
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static DTENTRY Ldt[] = {
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{ 0x0000, 0, 0x00, 0x0000 }, /* 0: empty */
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};
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static DTENTRY idt2[256] = { 0 };
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static unsigned char Tss[256];
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static struct dtr FreeBSDGdtr = { sizeof FreeBSDGdt - 1, 0 };
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static struct dtr Gdtr = { sizeof gdt2 - 1, 0 };
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static struct dtr Idtr = { sizeof idt2 - 1, 0 };
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struct bootinfo bootinfo;
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int VCPIboot;
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int pm_copy(char far *from, unsigned long to, unsigned long count)
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{
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unsigned char status;
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unsigned short cnt = (unsigned short) count;
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if (count == 0l) return -1; /* count has to be > 0!! */
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gdt[2].limit = cnt-1; /* so much bytes to receive */
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gdt[2].addr = _FP_SEG(from)*0x10l+_FP_OFF(from);
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gdt[2].rights = 0x92; /* Data Segment: r/w */
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gdt[3].limit = cnt-1; /* so much bytes to read */
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gdt[3].addr = to; /* from HiMem */
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gdt[3].rights = 0x92; /* Data Segment: r/w */
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cnt >>= 1;
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_asm {
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pusha
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mov ah,87h ; move words
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mov cx,cnt ; that many
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mov bx,seg gdt ; es:si points to the GDT
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mov es,bx
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mov si,offset gdt
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int 15h ; now move the memory block
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mov status,ah ; status is the return value:
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; 0 .. no error,
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; 1 .. parity error,
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; 2 .. exception interrupt
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; 3 .. gate A20 failed
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popa
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}
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return (int) status;
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}
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static int pm_enter(void)
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{
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unsigned char status;
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unsigned int segment;
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/* setup GDT entry 1: GDT */
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gdt2[1].limit = sizeof(gdt2)-1;
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gdt2[1].addr = ptr2lin(gdt2);
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gdt2[1].rights = 0x92; /* Data Segment: r/w */
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/* setup GDT entry 2: IDT */
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gdt2[2].limit = sizeof(idt2)-1;
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gdt2[2].addr = ptr2lin(idt2);
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gdt2[2].rights = 0x92; /* Data Segment: r/w */
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/* setup GDT entry 3: DS */
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_asm mov segment,ds
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gdt2[3].limit = 0xffff; /* max. offset */
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gdt2[3].addr = segment*0x10l; /* segment starts at */
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gdt2[3].rights = 0x92; /* Data Segment: r/w */
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/* setup GDT entry 4: ES */
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_asm mov segment,es
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gdt2[4].limit = 0xffff; /* max. offset */
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gdt2[4].addr = segment*0x10l; /* segment starts at */
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gdt2[4].rights = 0x92; /* Data Segment: r/w */
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/* setup GDT entry 5: SS */
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_asm mov segment,ss
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gdt2[5].limit = 0; /* max. offset = 64 K!! */
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gdt2[5].addr = segment*0x10l; /* segment starts at */
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gdt2[5].rights = 0x96; /* Stack Segment: r/w, expansion direction=down */
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/* setup GDT entry 7: uninitialized! */
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/* setup GDT entry 6: CS */
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_asm mov segment,cs
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gdt2[6].limit = 0xffff; /* max. offset */
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gdt2[6].addr = segment*0x10l; /* segment starts at */
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gdt2[6].rights = 0x9a; /* Code Segment: execute only */
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_asm {
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pusha
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mov ah,89h ; enter protected mode
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mov bx,seg gdt2 ; es:si points to the GDT
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mov es,bx
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mov si,offset gdt2
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mov bx,2820h ; setup Interrupt Levels
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int 15h ; now move the memory block
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mov status,ah ; status is the return value and 0 if no error occurred
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popa
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}
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if (status) return (int) status;/* no protected mode; return status */
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_asm {
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mov ax,30h
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mov word ptr ss:[bp+4],ax ; patch code selector
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}
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return 0;
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}
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static void setupVCPI(void)
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{
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unsigned int segment;
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/* setup GDT entry 1: VCPI 1 (code) */
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gdt2[1].limit = 0; /* max. offset */
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gdt2[1].addr = 0; /* segment starts at */
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gdt2[1].rights = 0; /* Data Segment: r/w */
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/* setup GDT entry 2: VCPI 2 */
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gdt2[2].limit = 0; /* max. offset */
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gdt2[2].addr = 0; /* segment starts at */
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gdt2[2].rights = 0; /* Data Segment: r/w */
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/* setup GDT entry 3: VCPI 3 */
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gdt2[3].limit = 0; /* max. offset */
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gdt2[3].addr = 0; /* segment starts at */
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gdt2[3].rights = 0; /* Data Segment: r/w */
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/* setup GDT entry 4: code segment (use16) */
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_asm mov segment,cs
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gdt2[4].limit = 0xffff; /* max. offset */
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gdt2[4].addr = segment*0x10l; /* segment starts at */
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gdt2[4].rights = 0x9a; /* Code Segment */
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/* setup GDT entry 5: data segment (use16) */
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_asm mov segment,ds
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gdt2[5].limit = 0xffff; /* max. offset */
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gdt2[5].addr = segment*0x10l; /* segment starts at */
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gdt2[5].rights = 0x92; /* Data Segment: r/w */
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/* setup GDT entry 6: stack segment */
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_asm mov segment,ss
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gdt2[6].limit = 0; /* max. offset */
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gdt2[6].addr = segment*0x10l; /* segment starts at */
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gdt2[6].rights = 0x96; /* Stack Segment: r/w */
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/* setup GDT entry 7: LDT selector */
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gdt2[7].limit = 7; /* max. offset */
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gdt2[7].addr = ptr2lin(Ldt); /* segment starts at */
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gdt2[7].rights = 0x82; /* Data Segment: r/w */
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/* setup GDT entry 8: 286-TSS */
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gdt2[8].limit = 43; /* max. offset */
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gdt2[8].addr = ptr2lin(Tss); /* segment starts at */
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gdt2[8].rights = 0x81; /* TSS */
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}
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long get_high_memory(long size)
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{
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int kb = ((int) (size/1024l)+3)&0xfffc; /* we need this much KB */
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int lo, hi, vcpiVer, vcpiStatus;
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int (far *xms_entry)();
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FILE *fp;
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/*
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* Let's check for VCPI services.
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*/
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fp = fopen("EMMXXXX0", "rb");
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if (fp) {
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fclose(fp);
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_asm {
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pusha
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mov ax,0de00h
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int 67h
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mov vcpiVer,bx
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mov vcpiStatus,ax
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popa
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}
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if (!(vcpiStatus&0xff00)) {
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VCPIboot = 1;
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printf("VCPI services Version %d.%d detected!\n", vcpiVer>>8, vcpiVer&0xff);
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}
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}
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/*
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* I don't know why, but 386max seems to use the first 64 KB of that
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* XMS area?! So I allocate more ram than I need!
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*/
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kb += 128;
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_asm {
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pusha
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mov ax,4300h
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int 2fh ; let's look if we have XMS
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cmp al,80h
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je wehaveit ; ok, we have it
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popa
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}
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return 0x110000l; /* default load address */
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no: _asm popa
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return 0l;
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_asm {
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wehaveit: mov ax,4310h
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int 2fh ; get xms entry point
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mov word ptr [xms_entry],bx
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mov word ptr [xms_entry+2],es
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mov ah,8h
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call [xms_entry]
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cmp ax,kb
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jb no
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mov dx,kb
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mov ah,9h
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call [xms_entry] ; get memory
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cmp ax,0
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je no ; sorry, no memory
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mov ah,0ch
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call [xms_entry] ; lock memory block (dx = handle)
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cmp ax,0
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je no
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mov lo,bx
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mov hi,dx
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popa
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}
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return (long)hi*0x10000l+(long)lo + 128l*1024l;
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}
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void startprog(long hmaddress, long hmsize, long startaddr, long loadflags,
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long bootdev)
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{
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long GDTaddr=ptr2lin(FreeBSDGdt);
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long *stack=_MK_FP(0x9f00, 0); /* prepare stack for starting the kernel */
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unsigned int pmseg, pmoff;
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unsigned int segment, pcxoff, psioff, pdioff;
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long h, BOOTaddr, ourret;
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unsigned char *page;
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int status;
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/*
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* The MSVC 1.5 inline assembler is not able to work with
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* 386 opcodes (ie. extended registers like eax). So we have
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* to use a workaround (god save Micro$oft and their customers ;)
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*/
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_asm {
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mov segment,cs
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mov ax, offset our_return
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mov pmoff,ax
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}
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BOOTaddr = segment*0x10l;
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ourret = BOOTaddr + (long) pmoff;
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_asm {
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push ds
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mov ax,cs
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mov ds,ax
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mov bx,offset lab ; patch the far jump after
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mov byte ptr ds:[patch],bl ; switching gdt for FreeBSD
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mov byte ptr ds:[patch+1],bh
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mov bx,offset pcx
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mov pcxoff,bx
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mov bx,offset psi
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mov psioff,bx
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mov bx,offset pdi
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mov pdioff,bx
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mov segment,ds
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pop ds
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}
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*((long *)_MK_FP(segment, pcxoff+1)) = hmsize;
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*((long *)_MK_FP(segment, psioff+1)) = hmaddress;
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*((long *)_MK_FP(segment, pdioff+1)) = startaddr;
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h = ptr2lin(&VCPI);
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_asm {
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push ds
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mov ax,cs
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mov ds,ax
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mov bx,word ptr ss:[h]
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mov cx,word ptr ss:[h+2]
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mov byte ptr ds:[patch2+1],bl
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mov byte ptr ds:[patch2+2],bh
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mov byte ptr ds:[patch2+3],cl
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mov byte ptr ds:[patch2+4],ch
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pop ds
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}
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/*
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* Setup the stack for executing the kernel. These parameters are
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* put on the stack in reversed order (addresses are INCREMENTED)!
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*/
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*stack++ = startaddr; /* that's the startaddress */
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*stack++ = 8l; /* new CS */
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*stack++ = ourret; /* ourreturn */
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*stack++ = loadflags; /* howto */
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*stack++ = bootdev; /* bootdev */
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*stack++ = 0l; /* Parameter 4 */
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*stack++ = 0l; /* Parameter 5 */
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*stack++ = 0l; /* Parameter 6 */
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*stack++ = ptr2lin(&bootinfo); /* bootinfo */
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/*
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* Initialize FreeBSD GDT and GDTR
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*/
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FreeBSDGdtr.base = GDTaddr;
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FreeBSDGdt[3].addr = BOOTaddr;
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/*
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* Now, we have to start the kernel at the given startaddress. To do this, we must
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* switch to protected mode using INT15 with AH=0x89. This call uses its own layout
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* of the GDT, so we switch to our own GDT after we return from the INT15 call. But
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* before we do this, we must copy the 64 K which overwrites the HIMEM at 0x100000.
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*/
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if (!VCPIboot) {
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if (!(status=pm_enter())) {
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_asm {
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cli
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mov ax,18h
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mov ds,ax
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}
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goto nowgo;
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}
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fprintf(stderr, "Can't switch to protected mode!\n");
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fprintf(stderr, "Giving up :-(!\n");
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exit(0);
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}
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/*
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* OK. Let's use VCPI services.
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*/
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Gdtr.base = ptr2lin(gdt2);
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Idtr.base = ptr2lin(idt2);
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setupVCPI();
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page = malloc(8192); /* allocate 8 KB */
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if (!page) {
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fprintf(stderr, "not enough memory!\n");
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exit(0);
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}
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memset(page, 0, 8192);
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h = (ptr2lin(page)+4095l) & 0xfffff000l;
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pmseg = (unsigned short) (h>>4l);
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/*
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* We *do* have VCPI services, so let's get the protected mode
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* interface and page table 0 from the server.
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*/
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_asm {
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push ds
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push si
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push di
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mov ax,seg gdt2
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mov ds,ax
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mov ax,offset gdt2
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add ax,8
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mov si,ax
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mov ax,pmseg
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mov es,ax
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xor di,di
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mov ax,0xde01
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int 0x67
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pop di
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pop si
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pop ds
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}
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/*
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* setup values for the mode change call
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*/
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*((unsigned long *) MK_FP(pmseg,0x1000)) = h+3l;
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VCPI.cr3 = h+0x1000l; /* page dir is the next page */
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VCPI.GdtrAddress = ptr2lin(&Gdtr);
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VCPI.IdtrAddress = ptr2lin(&Idtr);
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VCPI.LDTR = 7*8;
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VCPI.TR = 8*8;
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_asm {
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mov ax,offset nowgoVCPI
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mov pmoff,ax
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}
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VCPI.EIP = (long) pmoff;
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VCPI.CS = 4*8;
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_asm {
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cli
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data32
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patch2: mov si,0
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_emit 0
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_emit 0
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mov ax,0de0ch
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int 67h
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nowgoVCPI: ; we are now executing in protected mode
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; first, we turn paging off!
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data32
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_emit 0fh ; this is "mov eax,CR0"
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_emit 20h ;
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_emit 0c0h ;
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data32
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and ax,0ffffh
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_emit 0ffh
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_emit 7fh
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data32
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_emit 0fh ; this is "mov CR0,eax"
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_emit 22h ; and turns paging off
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_emit 0c0h ;
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data32
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xor ax,ax
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data32
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_emit 0fh ; this is "mov CR3,eax"
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_emit 22h ; and clears the page cache
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_emit 0d8h ;
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|
|
|
mov ax,28h
|
|
mov ds,ax ; load new DS
|
|
mov es,ax
|
|
mov ax,6*8
|
|
mov ss,ax
|
|
}
|
|
|
|
/*******************************************************************************
|
|
* now this is all executed in protected mode!!!
|
|
*/
|
|
|
|
/* setup new gdt for the FreeBSD kernel */
|
|
_asm {
|
|
nowgo: cli
|
|
lgdt FreeBSDGdtr
|
|
|
|
data32
|
|
_emit 0eah ; far jump to "lab" (switch cs)
|
|
patch: _emit 0 ; these two bytes are patched with the
|
|
_emit 0 ; correct offset of "lab"
|
|
_emit 0
|
|
_emit 0
|
|
_emit 18h
|
|
_emit 0
|
|
|
|
; Setup SS, DS and ES registers with correct values, initialize the
|
|
; stackpointer to the correct value and execute kernel
|
|
|
|
lab: mov bx,10h
|
|
_emit 0
|
|
_emit 0
|
|
mov ds,bx
|
|
mov es,bx
|
|
mov ss,bx
|
|
|
|
; move kernel to its correct address
|
|
|
|
pcx: _emit 0b9h ; Micro$oft knows, why "mov cx,0" does not
|
|
_emit 0 ; work here
|
|
_emit 0
|
|
_emit 0
|
|
_emit 0
|
|
psi: _emit 0beh ; mov si,0
|
|
_emit 0
|
|
_emit 0
|
|
_emit 0
|
|
_emit 0
|
|
pdi: _emit 0bfh ; mov di,0
|
|
_emit 0
|
|
_emit 0
|
|
_emit 0x10
|
|
_emit 0
|
|
|
|
rep movsb
|
|
|
|
; MSVC is unable to assemble this instruction: mov esp,09f000h
|
|
|
|
mov sp,0f000h
|
|
_emit 9h
|
|
_emit 0
|
|
retf ; execute kernel
|
|
our_return: jmp our_return
|
|
}
|
|
/* not reached */
|
|
}
|