WebSVN - shark - Rev 2 - /shark/branches/pj/oslib/xlib/vm86.c

/* Project: OSLib
* Description: The OS Construction Kit
* Date: 1.6.2000
* Idea by: Luca Abeni & Gerardo Lamastra
*
* OSLib is an SO project aimed at developing a common, easy-to-use
* low-level infrastructure for developing OS kernels and Embedded
* Applications; it partially derives from the HARTIK project but it
* currently is independently developed.
*
* OSLib is distributed under GPL License, and some of its code has
* been derived from the Linux kernel source; also some important
* ideas come from studying the DJGPP go32 extender.
*
* We acknowledge the Linux Community, Free Software Foundation,
* D.J. Delorie and all the other developers who believe in the
* freedom of software and ideas.
*
* For legalese, check out the included GPL license.
*/

/* File: Vm86.C
*
* VM86 mode switch routines!
* This is basically an alternative way of invoking the
* BIOS service routines; it is very useful to support
* native VBE compliant Video card, without writing an explicit driver
*/

#include <ll/i386/mem.h>
#include <ll/i386/x-bios.h>
#include <ll/i386/hw-func.h>
#include <ll/i386/hw-instr.h>
#include <ll/i386/cons.h>
#include <ll/i386/error.h>

FILE(VM - 86);

/*
#define __LL_DEBUG__
#define __DUMB_CODE__
#define __CHK_IO__
*/

#define VM86_STACK_SIZE 1024

/* TSS optional section */
static BYTE vm86_stack0[VM86_STACK_SIZE];

static struct {
TSS t;
DWORD io_map[2048];
} vm86_TSS;
static LIN_ADDR vm86_stack;
static LIN_ADDR vm86_iretAddress;

DWORD *GLOBesp;

#ifdef __DUMB_CODE__
static LIN_ADDR vm86_code;
static BYTE prova86[] = {
0x1e, /* push ds */
0xb8, 0x00, 0xb8, /* mov ax,0xb800 */
0x8e, 0xd8, /* mov ds,ax */
0xbf, 0x9e, 0x00, /* mov di,0x009e (158) */
0xb0, 0x2a, /* mov ax,'*' */
0x88, 0x05, /* mov ds:[di],al */
0x1f, /* pop ds */
0xcd, 0x40, /*??? */
#ifdef __CHK_IO__
0xb0, 0x00, /* movb $0x0,%al */
0x66, 0xba, 0x80, 0x00, /* movw $0x80,%dx */
0x66, 0xef, /* outw %ax, (%dx) */
#endif
0xcf, /* iret */
0xf4, /* hlt */
0
};
#endif

#ifdef __LL_DEBUG__
static BYTE vm86_retAddr[] = {
0x1e, /* push ds */
0xb8, 0x00, 0xb8, /* mov ax,0xb800 */
0x8e, 0xd8, /* mov ds,ax */
0xbf, 0x3e, 0x01, /* mov di,0x013c (316) */
0xb0, '%', /* mov ax,'%' */
0x88, 0x05, /* mov ds:[di],al */
0x1f, /* pop ds */
0xcd, 0x48
}; /* int 0x48 */
#else
static BYTE vm86_retAddr[] = { 0xcd, 0x48 }; /* int 48h */
#endif

/* This is the return point from V86 mode, called through int 0x48
* (see vm86-exc.s). We double check that this function is called in
* the V86 TSS. Otherwise, Panic!!!
*/
void vm86_return(DWORD * tos)
{
CONTEXT c = get_TR();
#ifdef __LL_DEBUG__
DWORD cs, eip;
void *esp;
DWORD a;
/* message("Gotta code=%d [0 called from GPF/1 int 0x48]\n",code);*/
#endif
if (c == X_VM86_TSS) {
GLOBesp = tos;
#ifdef __LL_DEBUG__
message("TSS CS=%x IP=%lx\n", vm86_TSS.t.cs, vm86_TSS.t.eip);
message("Switching to %x\n", vm86_TSS.t.back_link);
a = (DWORD) (vm86_iretAddress);
cs = (a & 0xFF000) >> 4;
eip = (a & 0xFFF);
message("Real-Mode Address is CS=%lx IP=%lx\nLinear=%lx\n", cs,
eip, a);
esp = (void *) (tos);
message("Stack frame: %p %lx %lx\n",
esp, vm86_TSS.t.esp0, vm86_TSS.t.esp);
message("%lx ", lmempeekd(esp)); /* bp */
message("%lx ", lmempeekd(esp + 4)); /* eip */
message("%lx ", lmempeekd(esp + 8)); /* 0x0d */
message("%lx\n", lmempeekd(esp + 12)); /* error code */
/* The error code is given by the selector causing shifted and or-ed with
3 bits: [LDT/GDT | IDT | Ext/Int]
If IDT == 1 -> the fault was provoked bu an interrupt (Internal if the
Ext/Int bit is 0, External if the bit is 1)
Else the LDT/GDT bit shows if the selector belongs to the LDT (if 1)
or GDT (if 0)
*/
message("%lx ", lmempeekd(esp + 16)); /* EIP of faulting instr */
message("%lx ", lmempeekd(esp + 20)); /* CS of faulting instr */
message("%lx ", lmempeekd(esp + 24)); /* EFLAGS */
message("%lx\n", lmempeekd(esp + 28)); /* old ESP */
message("%lx ", lmempeekd(esp + 32)); /* old SS */
message("%lx ", lmempeekd(esp + 36)); /* old ES */
message("%lx ", lmempeekd(esp + 40)); /* old DS */
message("%lx\n", lmempeekd(esp + 44)); /* old FS */
#endif
ll_context_load(vm86_TSS.t.back_link);
}
halt();
}

extern void vm86_exc(void);

/* Just a debugging function; it dumps the status of the TSS */
void vm86_dump_TSS(void)
{
BYTE acc, gran;
DWORD base, lim;
message("vm86_TSS.t dump\n");
message("Flag: %lx\n", vm86_TSS.t.eflags);
message("SS: %hx SP:%lx\n", vm86_TSS.t.ss, vm86_TSS.t.esp);
message("Stack0: %hx:%lx\n", vm86_TSS.t.ss0, vm86_TSS.t.esp0);
message("Stack1: %hx:%lx\n", vm86_TSS.t.ss1, vm86_TSS.t.esp1);
message("Stack2: %hx:%lx\n", vm86_TSS.t.ss2, vm86_TSS.t.esp2);
message("CS: %hx IP: %lx", vm86_TSS.t.cs, vm86_TSS.t.eip);
message("DS: %hx\n", vm86_TSS.t.ds);
base = GDT_read(X_VM86_TSS, &lim, &acc, &gran);
message("Base : %lx Lim : %lx Acc : %x Gran %x\n",
base, lim, (unsigned) (acc), (unsigned) (gran));
}

void vm86_init(void)
{
int register i;

/* Init the DOS memory allocator */
// DOS_mem_init();

/* First of all, we need to setup a GDT entries to
* allow vm86 task execution. We just need a free 386 TSS, which
* will be used to store the execution context of the virtual 8086
* task
*/
GDT_place(X_VM86_TSS, (DWORD) (&vm86_TSS),
sizeof(vm86_TSS), FREE_TSS386, GRAN_16);
IDT_place(0x48, vm86_exc);

/* Prepare a real-mode stack, obtaining it from the
* DOS memory allocator!
* 8K should be OK! Stack top is vm86_stack + SIZE!
*/
vm86_stack = DOS_alloc(VM86_STACK_SIZE * 2);
vm86_stack += VM86_STACK_SIZE / 2;

/* Create a location of DOS memory containing the
* opcode sequence which will generate a GPF
* We use the privileged instruction hlt to do it
*/
vm86_iretAddress = DOS_alloc(sizeof(vm86_retAddr));
memcpy(vm86_iretAddress, vm86_retAddr, sizeof(vm86_retAddr));
#ifdef __LL_DEBUG__
message("PM reentry linear address=%p\n", vm86_iretAddress);
#endif
#ifdef __DUMB_CODE__
vm86_code = DOS_alloc(2048);
lmemcpy(vm86_code, prova86, sizeof(prova86));
#endif
/* Zero the PM/Ring[1,2] ss:esp; they're unused! */
vm86_TSS.t.esp1 = 0;
vm86_TSS.t.esp2 = 0;
vm86_TSS.t.ss1 = 0;
vm86_TSS.t.ss2 = 0;
/* Use only the GDT */
vm86_TSS.t.ldt = 0;
/* No paging activated */
vm86_TSS.t.cr3 = 0;
vm86_TSS.t.trap = 0;
/* Yeah, free access to any I/O port; we trust BIOS anyway! */
/* Here is the explanation: we have 65536 I/O ports... each bit
* in the io_map masks/unmasks the exception for the given I/O port
* If the bit is set, an exception is generated; otherwise, if the bit
* is clear, everythings works fine...
* Because of alignment problem, we need to add an extra byte all set
* to 1, according to Intel manuals
*/
vm86_TSS.t.io_base = (DWORD) (&(vm86_TSS.io_map)) -
(DWORD) (&(vm86_TSS));
for (i = 0; i < 2047; i++)
vm86_TSS.io_map[i] = 0;
vm86_TSS.io_map[2047] = 0xFF000000;
}

int vm86_callBIOS(int service, X_REGS16 * in, X_REGS16 * out,
X_SREGS16 * s)
{
DWORD vm86_tmpAddr;
DWORD vm86_flags, vm86_cs, vm86_ip;
LIN_ADDR vm86_stackPtr;
DWORD *IRQTable_entry;

if (service < 0x10 || in == NULL)
return -1;
/* Setup the stack frame */
vm86_tmpAddr = (DWORD) (vm86_stack);
vm86_TSS.t.ss = (vm86_tmpAddr & 0xFF000) >> 4;
vm86_TSS.t.ebp = vm86_TSS.t.esp = (vm86_tmpAddr & 0x0FFF)
+ VM86_STACK_SIZE - 6;
/* Build an iret stack frame which returns to vm86_iretAddress */
vm86_tmpAddr = (DWORD) (vm86_iretAddress);
vm86_cs = (vm86_tmpAddr & 0xFF000) >> 4;
vm86_ip = (vm86_tmpAddr & 0xFFF);
vm86_flags = 0; /* CPU_FLAG_VM | CPU_FLAG_IOPL; */
vm86_stackPtr = vm86_stack + VM86_STACK_SIZE;
lmempokew(vm86_stackPtr - 6, vm86_ip);
lmempokew(vm86_stackPtr - 4, vm86_cs);
lmempokew(vm86_stackPtr - 2, vm86_flags);
#ifdef __LL_DEBUG__
message("Stack: %lx SS: %lx SP: %lx\n",
vm86_tmpAddr + VM86_STACK_SIZE, (DWORD) vm86_TSS.t.ss,
vm86_TSS.t.esp);
#endif
/* Wanted VM86 mode + IOPL = 3! */
vm86_TSS.t.eflags = CPU_FLAG_VM | CPU_FLAG_IOPL;
/* Preload some standard values into the registers */
vm86_TSS.t.ss0 = X_FLATDATA_SEL;
vm86_TSS.t.esp0 = (DWORD) & (vm86_stack0[VM86_STACK_SIZE - 1]);

#ifdef __DUMB_CODE__
vm86_TSS.t.cs = ((DWORD) (vm86_code) & 0xFFFF0) >> 4;
vm86_TSS.t.eip = ((DWORD) (vm86_code) & 0x000F);
#ifdef __LL_DEBUG_
message("(DUMB CODE) CS:%x IP:%x/%x\n",
(DWORD) vm86_TSS.t.cs, vm86_TSS.t.eip, &prova86);
message("(DUMB CODE) Go...\n");
#endif
vm86_TSS.t.back_link = ll_context_save();
ll_context_load(X_VM86_TSS);

#ifdef __LL_DEBUG_
message("(DUMB CODE) I am back...\n");
#endif
#else
/* Copy the parms from the X_*REGS structures in the vm86 TSS */
vm86_TSS.t.eax = (DWORD) in->x.ax;
vm86_TSS.t.ebx = (DWORD) in->x.bx;
vm86_TSS.t.ecx = (DWORD) in->x.cx;
vm86_TSS.t.edx = (DWORD) in->x.dx;
vm86_TSS.t.esi = (DWORD) in->x.si;
vm86_TSS.t.edi = (DWORD) in->x.di;
/* IF Segment registers are required, copy them... */
if (s != NULL) {
vm86_TSS.t.es = (WORD) s->es;
vm86_TSS.t.ds = (WORD) s->ds;
} else {
vm86_TSS.t.ds = vm86_TSS.t.ss;
vm86_TSS.t.es = vm86_TSS.t.ss;
}
vm86_TSS.t.gs = vm86_TSS.t.ss;
vm86_TSS.t.fs = vm86_TSS.t.ss;
/* Execute the BIOS call, fetching the CS:IP of the real interrupt
* handler from 0:0 (DOS irq table!)
*/
IRQTable_entry = (void *) (0L);
vm86_TSS.t.cs = ((IRQTable_entry[service]) & 0xFFFF0000) >> 16;
vm86_TSS.t.eip = ((IRQTable_entry[service]) & 0x0000FFFF);
#ifdef __LL_DEBUG__
message("CS:%hx IP:%lx\n", vm86_TSS.t.cs, vm86_TSS.t.eip);
#endif
/* Let's use the ll standard call... */
vm86_TSS.t.back_link = ll_context_save();
ll_context_load(X_VM86_TSS);
#ifdef __LL_DEBUG__
message("I am back...\n");
message("TSS CS=%hx IP=%lx\n", vm86_TSS.t.cs, vm86_TSS.t.eip);
{
char *xp = (char *) (vm86_iretAddress + 0xe);
message("PM reentry linear address=%p\n", vm86_iretAddress);
message("Executing code: %x ", (unsigned char) (*xp));
xp++;
message("%x\n", (unsigned char) (*xp));
}
#endif
/* Send back in the X_*REGS structure the value obtained with
* the real-mode interrupt call
*/
if (out != NULL) {
/*
out->x.ax = (WORD)vm86_TSS.t.eax;
out->x.bx = (WORD)vm86_TSS.t.ebx;
out->x.cx = (WORD)vm86_TSS.t.ecx;
out->x.dx = (WORD)vm86_TSS.t.edx;
out->x.si = (WORD)vm86_TSS.t.esi;
out->x.di = (WORD)vm86_TSS.t.edi;
out->x.cflag = (WORD)vm86_TSS.t.eflags;
*/
#ifdef __LL_DEBUG__
message("%x\n", (WORD) * (GLOBesp));
message("%x\n", (WORD) * (GLOBesp + 1));
/*EDI*/ message("%x\n", (WORD) * (GLOBesp + 2));
/*ESI*/ message("%x\n", (WORD) * (GLOBesp + 3));
/*EBP*/ message("%x\n", (WORD) * (GLOBesp + 4));
/*ESP*/ message("%x\n", (WORD) * (GLOBesp + 5));
/*EBX*/ message("%x\n", (WORD) * (GLOBesp + 6));
/*EDX*/
#endif
out->x.ax = (WORD) * (GLOBesp + 8);
out->x.bx = (WORD) * (GLOBesp + 5);
out->x.cx = (WORD) * (GLOBesp + 7);
out->x.dx = (WORD) * (GLOBesp + 6);
out->x.si = (WORD) * (GLOBesp + 2);
out->x.di = (WORD) * (GLOBesp + 1);
out->x.cflag = (WORD) * (GLOBesp);
}
if (s != NULL) {
s->es = vm86_TSS.t.es;
s->ds = vm86_TSS.t.ds;
}
#endif
return 1;
}

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