lrmi.c

超强的嵌入式GUI系统

	cx = CONTEXT_REGS.REG(ecx) & 0xffff;

	while (cx--)
		em_outs(size, seg);

	CONTEXT_REGS.REG(ecx) &= 0xffff0000;
}

static void
em_inbl(unsigned char literal)
{
	asm volatile ("inb %w1, %b0"
	 : "=a" (CONTEXT_REGS.REG(eax))
	 : "d" (literal), "0" (CONTEXT_REGS.REG(eax)));
}

static void
em_inb(void)
{
	asm volatile ("inb %w1, %b0"
	 : "=a" (CONTEXT_REGS.REG(eax))
	 : "d" (CONTEXT_REGS.REG(edx)), "0" (CONTEXT_REGS.REG(eax)));
}

static void
em_inw(void)
{
	asm volatile ("inw %w1, %w0"
	 : "=a" (CONTEXT_REGS.REG(eax))
	 : "d" (CONTEXT_REGS.REG(edx)), "0" (CONTEXT_REGS.REG(eax)));
}

static void
em_inl(void)
{
	asm volatile ("inl %w1, %0"
	 : "=a" (CONTEXT_REGS.REG(eax))
	 : "d" (CONTEXT_REGS.REG(edx)));
}

static void
em_outbl(unsigned char literal)
{
	asm volatile ("outb %b0, %w1"
	 : : "a" (CONTEXT_REGS.REG(eax)),
	 "d" (literal));
}

static void
em_outb(void)
{
	asm volatile ("outb %b0, %w1"
	 : : "a" (CONTEXT_REGS.REG(eax)),
	 "d" (CONTEXT_REGS.REG(edx)));
}

static void
em_outw(void)
{
	asm volatile ("outw %w0, %w1"
	 : : "a" (CONTEXT_REGS.REG(eax)),
	 "d" (CONTEXT_REGS.REG(edx)));
}

static void
em_outl(void)
{
	asm volatile ("outl %0, %w1"
	 : : "a" (CONTEXT_REGS.REG(eax)),
	 "d" (CONTEXT_REGS.REG(edx)));
}

static int
emulate(void)
{
	unsigned char *insn;
	struct {
		unsigned char seg;
		unsigned int size : 1;
		unsigned int rep : 1;
	} prefix = { DSEG, 0, 0 };
	int i = 0;

	insn = (unsigned char *)((unsigned int)CONTEXT_REGS.REG(cs) << 4);
	insn += CONTEXT_REGS.REG(eip);

	while (1) {
		if (insn[i] == 0x66) {
			prefix.size = 1 - prefix.size;
			i++;
		} else if (insn[i] == 0xf3) {
			prefix.rep = 1;
			i++;
		} else if (insn[i] == CSEG || insn[i] == SSEG
		 || insn[i] == DSEG || insn[i] == ESEG
		 || insn[i] == FSEG || insn[i] == GSEG) {
			prefix.seg = insn[i];
			i++;
		} else if (insn[i] == 0xf0 || insn[i] == 0xf2
		 || insn[i] == 0x67) {
			/* these prefixes are just ignored */
			i++;
		} else if (insn[i] == 0x6c) {
			if (prefix.rep)
				em_rep_ins(1);
			else
				em_ins(1);
			i++;
			break;
		} else if (insn[i] == 0x6d) {
			if (prefix.rep) {
				if (prefix.size)
					em_rep_ins(4);
				else
					em_rep_ins(2);
			} else {
				if (prefix.size)
					em_ins(4);
				else
					em_ins(2);
			}
			i++;
			break;
		} else if (insn[i] == 0x6e) {
			if (prefix.rep)
				em_rep_outs(1, prefix.seg);
			else
				em_outs(1, prefix.seg);
			i++;
			break;
		} else if (insn[i] == 0x6f) {
			if (prefix.rep) {
				if (prefix.size)
					em_rep_outs(4, prefix.seg);
				else
					em_rep_outs(2, prefix.seg);
			} else {
				if (prefix.size)
					em_outs(4, prefix.seg);
				else
					em_outs(2, prefix.seg);
			}
			i++;
			break;
		} else if (insn[i] == 0xe4) {
			em_inbl(insn[i + 1]);
			i += 2;
			break;
		} else if (insn[i] == 0xec) {
			em_inb();
			i++;
			break;
		} else if (insn[i] == 0xed) {
			if (prefix.size)
				em_inl();
			else
				em_inw();
			i++;
			break;
		} else if (insn[i] == 0xe6) {
			em_outbl(insn[i + 1]);
			i += 2;
			break;
		} else if (insn[i] == 0xee) {
			em_outb();
			i++;
			break;
		} else if (insn[i] == 0xef) {
			if (prefix.size)
				em_outl();
			else
				em_outw();

			i++;
			break;
		} else
			return 0;
	}

	CONTEXT_REGS.REG(eip) += i;
	return 1;
}


#if defined(__linux__)
/*
 I don't know how to make sure I get the right vm86() from libc.
 The one I want is syscall # 113 (vm86old() in libc 5, vm86() in glibc)
 which should be declared as "int vm86(struct vm86_struct *);" in
 <sys/vm86.h>.

 This just does syscall 113 with inline asm, which should work
 for both libc's (I hope).
*/
#if !defined(USE_LIBC_VM86)
static int
lrmi_vm86(struct vm86_struct *vm)
{
	int r;
#ifdef __PIC__
	asm volatile (
	 "pushl %%ebx\n\t"
	 "movl %2, %%ebx\n\t"
	 "int $0x80\n\t"
	 "popl %%ebx"
	 : "=a" (r)
	 : "0" (113), "r" (vm));
#else
	asm volatile (
	 "int $0x80"
	 : "=a" (r)
	 : "0" (113), "b" (vm));
#endif
	return r;
}
#else
#define lrmi_vm86 vm86
#endif
#endif /* __linux__ */


static void
debug_info(int vret)
{
#ifdef LRMI_DEBUG
	int i;
	unsigned char *p;

	fputs("vm86() failed\n", stderr);
	fprintf(stderr, "return = 0x%x\n", vret);
	fprintf(stderr, "eax = 0x%08x\n", CONTEXT_REGS.REG(eax));
	fprintf(stderr, "ebx = 0x%08x\n", CONTEXT_REGS.REG(ebx));
	fprintf(stderr, "ecx = 0x%08x\n", CONTEXT_REGS.REG(ecx));
	fprintf(stderr, "edx = 0x%08x\n", CONTEXT_REGS.REG(edx));
	fprintf(stderr, "esi = 0x%08x\n", CONTEXT_REGS.REG(esi));
	fprintf(stderr, "edi = 0x%08x\n", CONTEXT_REGS.REG(edi));
	fprintf(stderr, "ebp = 0x%08x\n", CONTEXT_REGS.REG(ebp));
	fprintf(stderr, "eip = 0x%08x\n", CONTEXT_REGS.REG(eip));
	fprintf(stderr, "cs  = 0x%04x\n", CONTEXT_REGS.REG(cs));
	fprintf(stderr, "esp = 0x%08x\n", CONTEXT_REGS.REG(esp));
	fprintf(stderr, "ss  = 0x%04x\n", CONTEXT_REGS.REG(ss));
	fprintf(stderr, "ds  = 0x%04x\n", CONTEXT_REGS.REG(ds));
	fprintf(stderr, "es  = 0x%04x\n", CONTEXT_REGS.REG(es));
	fprintf(stderr, "fs  = 0x%04x\n", CONTEXT_REGS.REG(fs));
	fprintf(stderr, "gs  = 0x%04x\n", CONTEXT_REGS.REG(gs));
	fprintf(stderr, "eflags  = 0x%08x\n", CONTEXT_REGS.REG(eflags));

	fputs("cs:ip = [ ", stderr);

	p = (unsigned char *)((CONTEXT_REGS.REG(cs) << 4) + (CONTEXT_REGS.REG(eip) & 0xffff));

	for (i = 0; i < 16; ++i)
		fprintf(stderr, "%02x ", (unsigned int)p[i]);

	fputs("]\n", stderr);
#endif
}


#if defined(__linux__)
static int
run_vm86(void)
{
	unsigned int vret;
	sigset_t all_sigs, old_sigs;
	unsigned long old_gs, old_fs;

	while (1) {
		// FIXME: may apply this to BSD equivalents?
		sigfillset(&all_sigs);
		sigprocmask(SIG_SETMASK, &all_sigs, &old_sigs);
		asm volatile ("mov %%gs, %0" : "=rm" (old_gs));
		asm volatile ("mov %%fs, %0" : "=rm" (old_fs));
		vret = lrmi_vm86(&context.vm);
		asm volatile ("mov %0, %%gs" :: "rm" (old_gs));
		asm volatile ("mov %0, %%fs" :: "rm" (old_fs));
		sigprocmask(SIG_SETMASK, &old_sigs, NULL);

		if (VM86_TYPE(vret) == VM86_INTx) {
			unsigned int v = VM86_ARG(vret);

			if (v == RETURN_TO_32_INT)
				return 1;

			pushw(CONTEXT_REGS.REG(eflags));
			pushw(CONTEXT_REGS.REG(cs));
			pushw(CONTEXT_REGS.REG(eip));

			CONTEXT_REGS.REG(cs) = get_int_seg(v);
			CONTEXT_REGS.REG(eip) = get_int_off(v);
			CONTEXT_REGS.REG(eflags) &= ~(VIF_MASK | TF_MASK);

			continue;
		}

		if (VM86_TYPE(vret) != VM86_UNKNOWN)
			break;

		if (!emulate())
			break;
	}

	debug_info(vret);

	return 0;
}
#elif defined(__NetBSD__) || defined(__FreeBSD__) || defined(__OpenBSD__)
#if defined(__NetBSD__) || defined(__OpenBSD__)
static void
vm86_callback(int sig, int code, struct sigcontext *sc)
{
	/* Sync our context with what the kernel develivered to us. */
	memcpy(&CONTEXT_REGS, sc, sizeof(*sc));

	switch (VM86_TYPE(code)) {
		case VM86_INTx:
		{
			unsigned int v = VM86_ARG(code);

			if (v == RETURN_TO_32_INT) {
				context.success = 1;
				longjmp(context.env, 1);
			}

			pushw(CONTEXT_REGS.REG(eflags));
			pushw(CONTEXT_REGS.REG(cs));
			pushw(CONTEXT_REGS.REG(eip));

			CONTEXT_REGS.REG(cs) = get_int_seg(v);
			CONTEXT_REGS.REG(eip) = get_int_off(v);
			CONTEXT_REGS.REG(eflags) &= ~(VIF_MASK | TF_MASK);

			break;
		}

		case VM86_UNKNOWN:
			if (emulate() == 0) {
				context.success = 0;
				context.vret = code;
				longjmp(context.env, 1);
			}
			break;

		default:
			context.success = 0;
			context.vret = code;
			longjmp(context.env, 1);
			return;
	}

	/* ...and sync our context back to the kernel. */
	memcpy(sc, &CONTEXT_REGS, sizeof(*sc));
}
#elif defined(__FreeBSD__)
static void
vm86_callback(int sig, int code, struct sigcontext *sc)
{
	unsigned char *addr;

	/* Sync our context with what the kernel develivered to us. */
	memcpy(&CONTEXT_REGS, sc, sizeof(*sc));

	if (code) {
		/* XXX probably need to call original signal handler here */
		context.success = 0;
		context.vret = code;
		longjmp(context.env, 1);
	}

	addr = (unsigned char *)((CONTEXT_REGS.REG(cs) << 4) +
		CONTEXT_REGS.REG(eip));

	if (addr[0] == 0xcd) { /* int opcode */
		if (addr[1] == RETURN_TO_32_INT) {
			context.success = 1;
			longjmp(context.env, 1);
		}

		pushw(CONTEXT_REGS.REG(eflags));
		pushw(CONTEXT_REGS.REG(cs));
		pushw(CONTEXT_REGS.REG(eip));

		CONTEXT_REGS.REG(cs) = get_int_seg(addr[1]);
		CONTEXT_REGS.REG(eip) = get_int_off(addr[1]);
		CONTEXT_REGS.REG(eflags) &= ~(VIF_MASK | TF_MASK);
	} else {
		if (emulate() == 0) {
			context.success = 0;
			longjmp(context.env, 1);
		}
	}

	/* ...and sync our context back to the kernel. */
	memcpy(sc, &CONTEXT_REGS, sizeof(*sc));
}
#endif /* __FreeBSD__ */

static int
run_vm86(void)
{
	if (context.old_sighandler) {
#ifdef LRMI_DEBUG
		fprintf(stderr, "run_vm86: callback already installed\n");
#endif
		return (0);
	}

#if defined(__NetBSD__) || defined(__OpenBSD__)
	context.old_sighandler = signal(SIGURG, (void (*)(int))vm86_callback);
#elif defined(__FreeBSD__)
	context.old_sighandler = signal(SIGBUS, (void (*)(int))vm86_callback);
#endif

	if (context.old_sighandler == (void *)-1) {
		context.old_sighandler = NULL;
#ifdef LRMI_DEBUG
		fprintf(stderr, "run_vm86: cannot install callback\n");
#endif
		return (0);
	}

	if (setjmp(context.env)) {
#if defined(__NetBSD__) || defined(__OpenBSD__)
		(void) signal(SIGURG, context.old_sighandler);
#elif defined(__FreeBSD__)
		(void) signal(SIGBUS, context.old_sighandler);
#endif
		context.old_sighandler = NULL;

		if (context.success)
			return (1);
		debug_info(context.vret);
		return (0);
	}

#if defined(__NetBSD__) || defined(__OpenBSD__)
	if (i386_vm86(&context.vm) == -1)
		return (0);
#elif defined(__FreeBSD__)
	if (i386_vm86(VM86_INIT, &context.vm.init))
		return 0;

	CONTEXT_REGS.REG(eflags) |= PSL_VM | PSL_VIF;
	sigreturn(&context.vm.uc);
#endif /* __FreeBSD__ */

	/* NOTREACHED */
	return (0);
}
#endif	/* __NetBSD__ || __FreeBSD__ || __OpenBSD__ */

int
LRMI_call(struct LRMI_regs *r)
{
	unsigned int vret;

	memset(&CONTEXT_REGS, 0, sizeof(CONTEXT_REGS));

	set_regs(r);

	CONTEXT_REGS.REG(cs) = r->cs;
	CONTEXT_REGS.REG(eip) = r->ip;

	if (r->ss == 0 && r->sp == 0) {
		CONTEXT_REGS.REG(ss) = context.stack_seg;
		CONTEXT_REGS.REG(esp) = context.stack_off;
	} else {
		CONTEXT_REGS.REG(ss) = r->ss;
		CONTEXT_REGS.REG(esp) = r->sp;
	}

	pushw(context.ret_seg);
	pushw(context.ret_off);

	vret = run_vm86();

	get_regs(r);

	return vret;
}


int
LRMI_int(int i, struct LRMI_regs *r)
{
	unsigned int vret;
	unsigned int seg, off;

	seg = get_int_seg(i);
	off = get_int_off(i);

	/*
	 If the interrupt is in regular memory, it's probably
	 still pointing at a dos TSR (which is now gone).
	*/
	if (seg < 0xa000 || (seg << 4) + off >= 0x100000) {
#ifdef LRMI_DEBUG
		fprintf(stderr, "Int 0x%x is not in rom (%04x:%04x)\n", i, seg, off);
#endif
		return 0;
	}

	memset(&CONTEXT_REGS, 0, sizeof(CONTEXT_REGS));

	set_regs(r);

	CONTEXT_REGS.REG(cs) = seg;
	CONTEXT_REGS.REG(eip) = off;

	if (r->ss == 0 && r->sp == 0) {
		CONTEXT_REGS.REG(ss) = context.stack_seg;
		CONTEXT_REGS.REG(esp) = context.stack_off;
	} else {
		CONTEXT_REGS.REG(ss) = r->ss;
		CONTEXT_REGS.REG(esp) = r->sp;
	}

	pushw(DEFAULT_VM86_FLAGS);
	pushw(context.ret_seg);
	pushw(context.ret_off);

	vret = run_vm86();

	get_regs(r);

	return vret;
}

#else /* (__linux__ || __NetBSD__ || __FreeBSD__ || __OpenBSD__) && __i386__ */
#warning "LRMI is not supported on your system!"
#endif