v86.c

gumstiz u-boot loader in linux

/*
 * Copyright 1999 Egbert Eich
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, provided that
 * the above copyright notice appear in all copies and that both that
 * copyright notice and this permission notice appear in supporting
 * documentation, and that the name of the authors not be used in
 * advertising or publicity pertaining to distribution of the software without
 * specific, written prior permission.  The authors makes no representations
 * about the suitability of this software for any purpose.  It is provided
 * "as is" without express or implied warranty.
 *
 * THE AUTHORS DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
 * EVENT SHALL THE AUTHORS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

#include "debug.h"
#include <sys/vm86.h>
#include <unistd.h>
#include <errno.h>
#include <asm/unistd.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <setjmp.h>
#include "v86bios.h"
#include "AsmMacros.h"

struct vm86_struct vm86s;

static int vm86_GP_fault(void);
static int vm86_do_int(int num);
static void dump_code(void);
static void dump_registers(void);
static void stack_trace(void);
static int vm86_rep(struct vm86_struct *ptr);

#define CPU_REG(x) (vm86s.regs.##x)
#define CPU_REG_LW(reg)      (*((CARD16 *)&CPU_REG(reg)))
#define CPU_REG_HW(reg)      (*((CARD16 *)&CPU_REG(reg) + 1))
#define CPU_REG_LB(reg)      (*(CARD8 *)&CPU_REG(e##reg))
#define SEG_ADR(type, seg, reg)  type((CPU_REG_LW(seg) << 4) \
				      + CPU_REG_LW(e##reg))
#define DF (1 << 10)

struct pio P;


void
setup_io(void)
{
    if (!Config.PrintPort && !Config.IoStatistics) {
    P.inb = (CARD8(*)(CARD16))inb;
    P.inw = (CARD16(*)(CARD16))inw;
    P.inl = (CARD32(*)(CARD16))inl;
    P.outb = (void(*)(CARD16,CARD8))outb;
    P.outw = (void(*)(CARD16,CARD16))outw;
    P.outl = (void(*)(CARD16,CARD32))outl;
    } else {
    P.inb = p_inb;
    P.inw = p_inw;
    P.inl = p_inl;
    P.outb = p_outb;
    P.outw = p_outw;
    P.outl = p_outl;
    }
}


static void
setup_vm86(unsigned long bios_start, i86biosRegsPtr regs)
{
    CARD32 eip;
    CARD16 cs;

    vm86s.flags = VM86_SCREEN_BITMAP;
    vm86s.flags = 0;
    vm86s.screen_bitmap = 0;
    vm86s.cpu_type = CPU_586;
    memset(&vm86s.int_revectored, 0xff,sizeof(vm86s.int_revectored)) ;
    memset(&vm86s.int21_revectored, 0xff,sizeof(vm86s.int21_revectored)) ;

    eip = bios_start & 0xFFFF;
    cs = (bios_start & 0xFF0000) >> 4;

    CPU_REG(eax) = regs->ax;
    CPU_REG(ebx) = regs->bx;
    CPU_REG(ecx) = regs->cx;
    CPU_REG(edx) = regs->dx;
    CPU_REG(esi) = 0;
    CPU_REG(edi) = regs->di;
    CPU_REG(ebp) = 0;
    CPU_REG(eip) = eip;
    CPU_REG(cs) = cs;
    CPU_REG(esp) = 0x100;
    CPU_REG(ss) = 0x30;               /* This is the standard pc bios stack */
    CPU_REG(es) = regs->es;
    CPU_REG(ds) = 0x40;               /* standard pc ds */
    CPU_REG(fs) = 0;
    CPU_REG(gs) = 0;
    CPU_REG(eflags) |= (VIF_MASK | VIP_MASK);
}

void
collect_bios_regs(i86biosRegsPtr regs)
{
    regs->ax = CPU_REG(eax);
    regs->bx = CPU_REG(ebx);
    regs->cx = CPU_REG(ecx);
    regs->dx = CPU_REG(edx);
    regs->es = CPU_REG(es);
    regs->ds = CPU_REG(ds);
    regs->di = CPU_REG(edi);
    regs->si = CPU_REG(esi);
}

static int
do_vm86(void)
{
    int retval;

#ifdef V86BIOS_DEBUG
    dump_registers();
#endif
/*    retval = SYS_vm86old(&vm86s); */
/*    retval = syscall(SYS_vm86old,&vm86s); */

    retval = vm86_rep(&vm86s);

    switch (VM86_TYPE(retval)) {
    case VM86_UNKNOWN:
	if (!vm86_GP_fault()) return 0;
	break;
    case VM86_STI:
	fprintf(stderr,"vm86_sti :-((\n");
	stack_trace();
	dump_code();
	return 0;
    case VM86_INTx:
	if (!vm86_do_int(VM86_ARG(retval))) {
	    fprintf(stderr,"\nUnknown vm86_int: %X\n\n",VM86_ARG(retval));
	    dump_registers();
	    return 0;
	}
	/* I'm not sure yet what to do if we can handle ints */
	break;
    case VM86_SIGNAL:
	fprintf(stderr,"received signal\n");
	return 0;
    default:
	fprintf(stderr,"unknown type(0x%x)=0x%x\n",
		VM86_ARG(retval),VM86_TYPE(retval));
	dump_registers();
	dump_code();
	stack_trace();
	return 0;
    }

    return 1;
}

static jmp_buf x86_esc;
static void
vmexit(int unused)
{
    longjmp(x86_esc,1);
}

void
do_x86(unsigned long bios_start, i86biosRegsPtr regs)
{
    static void (*org_handler)(int);

    setup_vm86(bios_start, regs);
    if (setjmp(x86_esc) == 0) {
	org_handler = signal(2,vmexit);
	while(do_vm86()) {};
	signal(2,org_handler);
	collect_bios_regs(regs);
    } else {
	signal(2,org_handler);
	printf("interrupted at 0x%x\n",((CARD16)CPU_REG(cs)) << 4
	   | (CARD16)CPU_REG(eip));
    }
}

/* get the linear address */
#define LIN_PREF_SI  ((pref_seg << 4) + CPU_REG_LW(esi))

#define LWECX       (prefix66 ^ prefix67 ? CPU_REG(ecx) : CPU_REG_LW(ecx))

static int
vm86_GP_fault(void)
{
    unsigned char *csp, *lina;
    CARD32 org_eip;
    int pref_seg;
    int done,is_rep,prefix66,prefix67;


    csp = lina = SEG_ADR((unsigned char *), cs, ip);
#ifdef V86BIOS_DEBUG
    printf("exception: \n");
    dump_code();
#endif

    is_rep = 0;
    prefix66 = prefix67 = 0;
    pref_seg = -1;

    /* eat up prefixes */
    done = 0;
    do {
	switch (*(csp++)) {
	case 0x66:      /* operand prefix */  prefix66=1; break;
	case 0x67:      /* address prefix */  prefix67=1; break;
	case 0x2e:      /* CS */              pref_seg=CPU_REG(cs); break;
	case 0x3e:      /* DS */              pref_seg=CPU_REG(ds); break;
	case 0x26:      /* ES */              pref_seg=CPU_REG(es); break;
	case 0x36:      /* SS */              pref_seg=CPU_REG(ss); break;
	case 0x65:      /* GS */              pref_seg=CPU_REG(gs); break;
	case 0x64:      /* FS */              pref_seg=CPU_REG(fs); break;
	case 0xf2:      /* repnz */
	case 0xf3:      /* rep */             is_rep=1; break;
	default: done=1;
	}
    } while (!done);
    csp--;   /* oops one too many */
    org_eip = CPU_REG(eip);
    CPU_REG_LW(eip) += (csp - lina);

    switch (*csp) {

    case 0x6c:                    /* insb */
	/* NOTE: ES can't be overwritten; prefixes 66,67 should use esi,edi,ecx
	 * but is anyone using extended regs in real mode? */
	/* WARNING: no test for DI wrapping! */
	CPU_REG_LW(edi) += port_rep_inb(CPU_REG_LW(edx),
					SEG_ADR((CARD8 *),es,di),
					CPU_REG_LW(eflags)&DF,
					(is_rep? LWECX:1));
	if (is_rep) LWECX = 0;
	CPU_REG_LW(eip)++;
	break;

    case 0x6d:                  /* (rep) insw / insd */
	/* NOTE: ES can't be overwritten */
	/* WARNING: no test for _DI wrapping! */
	if (prefix66) {
	    CPU_REG_LW(edi) += port_rep_inl(CPU_REG_LW(edx),
					    SEG_ADR((CARD32 *),es,di),
					    CPU_REG_LW(eflags)&DF,
					    (is_rep? LWECX:1));
	}
	else {
	    CPU_REG_LW(edi) += port_rep_inw(CPU_REG_LW(edx),
					    SEG_ADR((CARD16 *),es,di),
					    CPU_REG_LW(eflags)&DF,
					    (is_rep? LWECX:1));
	}
	if (is_rep) LWECX = 0;
	CPU_REG_LW(eip)++;
	break;

    case 0x6e:                  /* (rep) outsb */
	if (pref_seg < 0) pref_seg = CPU_REG_LW(ds);
	/* WARNING: no test for _SI wrapping! */
	CPU_REG_LW(esi) += port_rep_outb(CPU_REG_LW(edx),(CARD8*)LIN_PREF_SI,
					 CPU_REG_LW(eflags)&DF,
					 (is_rep? LWECX:1));
	if (is_rep) LWECX = 0;
	CPU_REG_LW(eip)++;
	break;

    case 0x6f:                  /* (rep) outsw / outsd */
	if (pref_seg < 0) pref_seg = CPU_REG_LW(ds);
	/* WARNING: no test for _SI wrapping! */
	if (prefix66) {
	    CPU_REG_LW(esi) += port_rep_outl(CPU_REG_LW(edx),
					     (CARD32 *)LIN_PREF_SI,
					     CPU_REG_LW(eflags)&DF,
					     (is_rep? LWECX:1));
	}
	else {
	    CPU_REG_LW(esi) += port_rep_outw(CPU_REG_LW(edx),
					     (CARD16 *)LIN_PREF_SI,
					     CPU_REG_LW(eflags)&DF,
					     (is_rep? LWECX:1));
	}
	if (is_rep) LWECX = 0;
	CPU_REG_LW(eip)++;
	break;

    case 0xe5:                  /* inw xx, inl xx */
	if (prefix66) CPU_REG(eax) = P.inl((int) csp[1]);
	else CPU_REG_LW(eax) = P.inw((int) csp[1]);
	CPU_REG_LW(eip) += 2;
	break;
    case 0xe4:                  /* inb xx */
	CPU_REG_LW(eax) &= ~(CARD32)0xff;
	CPU_REG_LB(ax) |= P.inb((int) csp[1]);
	CPU_REG_LW(eip) += 2;
	break;
    case 0xed:                  /* inw dx, inl dx */
	if (prefix66) CPU_REG(eax) = P.inl(CPU_REG_LW(edx));
	else CPU_REG_LW(eax) = P.inw(CPU_REG_LW(edx));
	CPU_REG_LW(eip) += 1;
	break;
    case 0xec:                  /* inb dx */
	CPU_REG_LW(eax) &= ~(CARD32)0xff;
	CPU_REG_LB(ax) |= P.inb(CPU_REG_LW(edx));
	CPU_REG_LW(eip) += 1;
	break;

    case 0xe7:                  /* outw xx */
	if (prefix66) P.outl((int)csp[1], CPU_REG(eax));
	else P.outw((int)csp[1], CPU_REG_LW(eax));
	CPU_REG_LW(eip) += 2;
	break;
    case 0xe6:                  /* outb xx */
	P.outb((int) csp[1], CPU_REG_LB(ax));
	CPU_REG_LW(eip) += 2;
	break;
    case 0xef:                  /* outw dx */
	if (prefix66) P.outl(CPU_REG_LW(edx), CPU_REG(eax));
	else P.outw(CPU_REG_LW(edx), CPU_REG_LW(eax));
	CPU_REG_LW(eip) += 1;
	break;
    case 0xee:                  /* outb dx */
	P.outb(CPU_REG_LW(edx), CPU_REG_LB(ax));
	CPU_REG_LW(eip) += 1;
	break;

    case 0xf4:
#ifdef V86BIOS_DEBUG
	printf("hlt at %p\n", lina);
#endif
	return 0;

    case 0x0f:
	fprintf(stderr,"CPU 0x0f Trap at eip=0x%lx\n",CPU_REG(eip));
	goto op0ferr;
	break;

    case 0xf0:                  /* lock */
    default:
	fprintf(stderr,"unknown reason for exception\n");
	dump_registers();
	stack_trace();
    op0ferr:
	dump_code();
	fprintf(stderr,"cannot continue\n");
	return 0;
    }                           /* end of switch() */
    return 1;
}

static int
vm86_do_int(int num)
{
    int val;
    struct regs86 regs;

    i_printf("int 0x%x received: ax:0x%lx",num,CPU_REG(eax));
    if (Config.PrintIp)
	i_printf(" at: 0x%x\n",getIP());
    else
	i_printf("\n");

    /* try to run bios interrupt */

    /* if not installed fall back */
#define COPY(x) regs.##x = CPU_REG(x)
#define COPY_R(x) CPU_REG(x) = regs.##x

    COPY(eax);
    COPY(ebx);
    COPY(ecx);
    COPY(edx);
    COPY(esi);
    COPY(edi);
    COPY(ebp);
    COPY(eip);
    COPY(esp);
    COPY(cs);
    COPY(ss);
    COPY(ds);
    COPY(es);
    COPY(fs);
    COPY(gs);
    COPY(eflags);

    if (!(val = int_handler(num,&regs)))
	if (!(val = run_bios_int(num,&regs)))
	    return val;

    COPY_R(eax);
    COPY_R(ebx);
    COPY_R(ecx);
    COPY_R(edx);
    COPY_R(esi);
    COPY_R(edi);
    COPY_R(ebp);
    COPY_R(eip);
    COPY_R(esp);
    COPY_R(cs);
    COPY_R(ss);
    COPY_R(ds);
    COPY_R(es);
    COPY_R(fs);
    COPY_R(gs);
    COPY_R(eflags);

    return val;
#undef COPY
#undef COPY_R
}

static void
dump_code(void)
{
    int i;
    unsigned char *lina = SEG_ADR((unsigned char *), cs, ip);

    fprintf(stderr,"code at 0x%8.8x: ",(CARD32)lina);
    for (i=0; i<0x10; i++)
	fprintf(stderr,"%2.2x ",*(lina + i));
    fprintf(stderr,"\n                    ");
    for (; i<0x20; i++)
	fprintf(stderr,"%2.2x ",*(lina + i));
    fprintf(stderr,"\n");
}

#define PRINT(x) fprintf(stderr,#x":%4.4x ",CPU_REG_LW(x))
#define PRINT_FLAGS(x) fprintf(stderr,#x":%8.8x ",CPU_REG_LW(x))
static void
dump_registers(void)
{
    PRINT(eip);
    PRINT(eax);
    PRINT(ebx);
    PRINT(ecx);
    PRINT(edx);
    PRINT(esi);
    PRINT(edi);
    PRINT(ebp);
    fprintf(stderr,"\n");
    PRINT(esp);
    PRINT(cs);
    PRINT(ss);
    PRINT(es);
    PRINT(ds);
    PRINT(fs);
    PRINT(gs);
    PRINT_FLAGS(eflags);
    fprintf(stderr,"\n");
}

static void
stack_trace(void)
{
    int i;
    unsigned char *stack = SEG_ADR((unsigned char *), ss, sp);

    fprintf(stderr,"stack at 0x%8.8lx:\n",(unsigned long)stack);
    for (i=0; i < 0x10; i++)
	fprintf(stderr,"%2.2x ",*(stack + i));
    fprintf(stderr,"\n");

}

static int
vm86_rep(struct vm86_struct *ptr)
{

    int __res;

    __asm__ __volatile__("int $0x80\n"
			 :"=a" (__res):"a" ((int)113),
			 "b" ((struct vm86_struct *)ptr));

	    if ((__res) < 0) {
		errno = -__res;
		__res=-1;
	    }
	    else errno = 0;
	    return __res;
}

#define pushw(base, ptr, val) \
__asm__ __volatile__( \
	"decw %w0\n\t" \
	"movb %h2,(%1,%0)\n\t" \
	"decw %w0\n\t" \
	"movb %b2,(%1,%0)" \
	: "=r" (ptr) \
	: "r" (base), "q" (val), "0" (ptr))

int
run_bios_int(int num, struct regs86 *regs)
{
    CARD16 *ssp;
    CARD32 sp;
    CARD32 eflags;

#ifdef V86BIOS_DEBUG
    static int firsttime = 1;
#endif
    /* check if bios vector is initialized */
    if (((CARD16*)0)[(num<<1)+1] == 0x0000) { /* SYS_BIOS_SEG ?*/
#ifdef V86BIOS_DEBUG
	i_printf("card BIOS not loaded\n");
#endif
	return 0;
    }

#ifdef V86BIOS_DEBUG
    if (firsttime) {
	dprint(0,0x3D0);
	firsttime = 0;
    }
#endif

    i_printf("calling card BIOS at: ");
    ssp = (CARD16*)(CPU_REG(ss)<<4);
    sp = (CARD32) CPU_REG_LW(esp);

    eflags = regs->eflags;
    eflags = ((eflags & VIF_MASK) != 0)
	? (eflags | IF_MASK) : (eflags & ~(CARD32) IF_MASK);
    pushw(ssp, sp, eflags);
    pushw(ssp, sp, regs->cs);
    pushw(ssp, sp, (CARD16)regs->eip);
    regs->esp -= 6;
    regs->cs = ((CARD16 *) 0)[(num << 1) + 1];
    regs->eip = (regs->eip & 0xFFFF0000) | ((CARD16 *) 0)[num << 1];
    i_printf("0x%x:%lx\n",regs->cs,regs->eip);
#ifdef V86BIOS_DEBUG
    dump_code();
#endif
    regs->eflags = regs->eflags
		       & ~(VIF_MASK | TF_MASK | IF_MASK | NT_MASK);
    return 1;
}

CARD32
getIntVect(int num)
{
    return ((CARD32*)0)[num];
}

CARD32
getIP(void)
{
    return (CPU_REG(cs) << 4) + CPU_REG(eip);
}