fpu_entry.c

freebsd v4.4内核源码

/*
 *  fpu_entry.c
 *
 * The entry function for wm-FPU-emu
 *
 *
 * Copyright (C) 1992,1993,1994
 *                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,
 *                       Australia.  E-mail   [e-mail]
 * All rights reserved.
 *
 * This copyright notice covers the redistribution and use of the
 * FPU emulator developed by W. Metzenthen. It covers only its use
 * in the 386BSD, FreeBSD and NetBSD operating systems. Any other
 * use is not permitted under this copyright.
 *
 * 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 include information specifying
 *    that source code for the emulator is freely available and include
 *    either:
 *      a) an offer to provide the source code for a nominal distribution
 *         fee, or
 *      b) list at least two alternative methods whereby the source
 *         can be obtained, e.g. a publically accessible bulletin board
 *         and an anonymous ftp site from which the software can be
 *         downloaded.
 * 3. All advertising materials specifically mentioning features or use of
 *    this emulator must acknowledge that it was developed by W. Metzenthen.
 * 4. The name of W. Metzenthen may not be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED ``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
 * W. METZENTHEN 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.
 *
 *
 * The purpose of this copyright, based upon the Berkeley copyright, is to
 * ensure that the covered software remains freely available to everyone.
 *
 * The software (with necessary differences) is also available, but under
 * the terms of the GNU copyleft, for the Linux operating system and for
 * the djgpp ms-dos extender.
 *
 * W. Metzenthen   June 1994.
 *
 * $FreeBSD: src/sys/gnu/i386/fpemul/fpu_entry.c,v 1.9.2.1 1999/09/05 08:09:39 peter Exp $
 *
 */

/*---------------------------------------------------------------------------+
 | Note:                                                                     |
 |    The file contains code which accesses user memory.                     |
 |    Emulator static data may change when user memory is accessed, due to   |
 |    other processes using the emulator while swapping is in progress.      |
 +---------------------------------------------------------------------------*/

/*---------------------------------------------------------------------------+
 | math_emulate() is the sole entry point for wm-FPU-emu                     |
 +---------------------------------------------------------------------------*/


#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/kernel.h>

#ifdef LKM
#include <sys/lkm.h>
#endif

#include <machine/cpu.h>
#include <machine/pcb.h>

#include <gnu/i386/fpemul/fpu_emu.h>
#include <gnu/i386/fpemul/fpu_system.h>
#include <gnu/i386/fpemul/exception.h>
#include <gnu/i386/fpemul/control_w.h>
#include <gnu/i386/fpemul/status_w.h>


#define __BAD__ Un_impl		/* Not implemented */

#define FPU_LOOKAHEAD   1       /* For performance boost */

#if FPU_LOOKAHEAD != 0          /* I think thet we have to limit the */
#define LOOKAHEAD_LIMIT	7	/* Max number of lookahead instructions*/
#endif                          /* Or else a prog consisting of a million */
                                /* fnops will spend all its time in kernel*/

#ifndef NO_UNDOC_CODE		/* Un-documented FPU op-codes supported by
				 * default. */

/* WARNING: These codes are not documented by Intel in their 80486 manual
   and may not work on FPU clones or later Intel FPUs. */

/* Changes to support the un-doc codes provided by Linus Torvalds. */

#define _d9_d8_ fstp_i		/* unofficial code (19) */
#define _dc_d0_ fcom_st		/* unofficial code (14) */
#define _dc_d8_ fcompst		/* unofficial code (1c) */
#define _dd_c8_ fxch_i		/* unofficial code (0d) */
#define _de_d0_ fcompst		/* unofficial code (16) */
#define _df_c0_ ffreep		/* unofficial code (07) ffree + pop */
#define _df_c8_ fxch_i		/* unofficial code (0f) */
#define _df_d0_ fstp_i		/* unofficial code (17) */
#define _df_d8_ fstp_i		/* unofficial code (1f) */

static FUNC st_instr_table[64] = {
	fadd__, fld_i_, __BAD__, __BAD__, fadd_i, ffree_, faddp_, _df_c0_,
	fmul__, fxch_i, __BAD__, __BAD__, fmul_i, _dd_c8_, fmulp_, _df_c8_,
	fcom_st, fp_nop, __BAD__, __BAD__, _dc_d0_, fst_i_, _de_d0_, _df_d0_,
	fcompst, _d9_d8_, __BAD__, __BAD__, _dc_d8_, fstp_i, fcompp, _df_d8_,
	fsub__, fp_etc, __BAD__, finit_, fsubri, fucom_, fsubrp, fstsw_,
	fsubr_, fconst, fucompp, __BAD__, fsub_i, fucomp, fsubp_, __BAD__,
	fdiv__, trig_a, __BAD__, __BAD__, fdivri, __BAD__, fdivrp, __BAD__,
	fdivr_, trig_b, __BAD__, __BAD__, fdiv_i, __BAD__, fdivp_, __BAD__,
};
#else				/* Support only documented FPU op-codes */

static FUNC st_instr_table[64] = {
	fadd__, fld_i_, __BAD__, __BAD__, fadd_i, ffree_, faddp_, __BAD__,
	fmul__, fxch_i, __BAD__, __BAD__, fmul_i, __BAD__, fmulp_, __BAD__,
	fcom_st, fp_nop, __BAD__, __BAD__, __BAD__, fst_i_, __BAD__, __BAD__,
	fcompst, __BAD__, __BAD__, __BAD__, __BAD__, fstp_i, fcompp, __BAD__,
	fsub__, fp_etc, __BAD__, finit_, fsubri, fucom_, fsubrp, fstsw_,
	fsubr_, fconst, fucompp, __BAD__, fsub_i, fucomp, fsubp_, __BAD__,
	fdiv__, trig_a, __BAD__, __BAD__, fdivri, __BAD__, fdivrp, __BAD__,
	fdivr_, trig_b, __BAD__, __BAD__, fdiv_i, __BAD__, fdivp_, __BAD__,
};
#endif				/* NO_UNDOC_CODE */


#define _NONE_ 0		/* Take no special action */
#define _REG0_ 1		/* Need to check for not empty st(0) */
#define _REGI_ 2		/* Need to check for not empty st(0) and
				 * st(rm) */
#define _REGi_ 0		/* Uses st(rm) */
#define _PUSH_ 3		/* Need to check for space to push onto stack */
#define _null_ 4		/* Function illegal or not implemented */
#define _REGIi 5		/* Uses st(0) and st(rm), result to st(rm) */
#define _REGIp 6		/* Uses st(0) and st(rm), result to st(rm)
				 * then pop */
#define _REGIc 0		/* Compare st(0) and st(rm) */
#define _REGIn 0		/* Uses st(0) and st(rm), but handle checks
				 * later */

#ifndef NO_UNDOC_CODE

/* Un-documented FPU op-codes supported by default. (see above) */

static unsigned char type_table[64] = {
	_REGI_, _NONE_, _null_, _null_, _REGIi, _REGi_, _REGIp, _REGi_,
	_REGI_, _REGIn, _null_, _null_, _REGIi, _REGI_, _REGIp, _REGI_,
	_REGIc, _NONE_, _null_, _null_, _REGIc, _REG0_, _REGIc, _REG0_,
	_REGIc, _REG0_, _null_, _null_, _REGIc, _REG0_, _REGIc, _REG0_,
	_REGI_, _NONE_, _null_, _NONE_, _REGIi, _REGIc, _REGIp, _NONE_,
	_REGI_, _NONE_, _REGIc, _null_, _REGIi, _REGIc, _REGIp, _null_,
	_REGI_, _NONE_, _null_, _null_, _REGIi, _null_, _REGIp, _null_,
	_REGI_, _NONE_, _null_, _null_, _REGIi, _null_, _REGIp, _null_
};
#else				/* Support only documented FPU op-codes */

static unsigned char type_table[64] = {
	_REGI_, _NONE_, _null_, _null_, _REGIi, _REGi_, _REGIp, _null_,
	_REGI_, _REGIn, _null_, _null_, _REGIi, _null_, _REGIp, _null_,
	_REGIc, _NONE_, _null_, _null_, _null_, _REG0_, _null_, _null_,
	_REGIc, _null_, _null_, _null_, _null_, _REG0_, _REGIc, _null_,
	_REGI_, _NONE_, _null_, _NONE_, _REGIi, _REGIc, _REGIp, _NONE_,
	_REGI_, _NONE_, _REGIc, _null_, _REGIi, _REGIc, _REGIp, _null_,
	_REGI_, _NONE_, _null_, _null_, _REGIi, _null_, _REGIp, _null_,
	_REGI_, _NONE_, _null_, _null_, _REGIi, _null_, _REGIp, _null_
};
#endif				/* NO_UNDOC_CODE */

/* Be careful when using any of these global variables...
   they might change if swapping is triggered */
unsigned char FPU_rm;
char    FPU_st0_tag;
FPU_REG *FPU_st0_ptr;

#ifdef PARANOID
char    emulating = 0;
#endif				/* PARANOID */

#define bswapw(x) __asm__("xchgb %%al,%%ah":"=a" (x):"0" ((short)x))
#define math_abort(signo) \
    FPU_EIP = FPU_ORIG_EIP;REENTRANT_CHECK(OFF);return(signo);

static int
math_emulate(struct trapframe * tframe)
{

	unsigned char FPU_modrm;
	unsigned short code;
#ifdef LOOKAHEAD_LIMIT
	int lookahead_limit = LOOKAHEAD_LIMIT;
#endif
#ifdef PARANOID
	if (emulating) {
		printf("ERROR: wm-FPU-emu is not RE-ENTRANT!\n");
	}
	REENTRANT_CHECK(ON);
#endif				/* PARANOID */

	if ((((struct pcb *) curproc->p_addr)->pcb_flags & FP_SOFTFP) == 0) {
		finit();
		control_word = __INITIAL_NPXCW__;
		((struct pcb *) curproc->p_addr)->pcb_flags |= FP_SOFTFP;
	}
	FPU_info = tframe;
	FPU_ORIG_EIP = FPU_EIP;	/* --pink-- */

	if (FPU_CS != 0x001f) {
		printf("math_emulate: %x : %x\n", FPU_CS, FPU_EIP);
		panic("FPU emulation in kernel");
	}
#ifdef notyet
	/* We cannot handle emulation in v86-mode */
	if (FPU_EFLAGS & 0x00020000) {
		FPU_ORIG_EIP = FPU_EIP;
		math_abort(FPU_info, SIGILL);
	}
#endif

	FPU_lookahead = FPU_LOOKAHEAD;
	if (curproc->p_flag & P_TRACED)
		FPU_lookahead = 0;

do_another_FPU_instruction:

	REENTRANT_CHECK(OFF);
	code = fuword((u_int *) FPU_EIP);
	REENTRANT_CHECK(ON);
	if ((code & 0xff) == 0x9b) {	/* fwait */
		if (status_word & SW_Summary)
			goto do_the_FPU_interrupt;
		else {
			FPU_EIP++;
			goto FPU_instruction_done;
		}
	}
	if (status_word & SW_Summary) {
		/* Ignore the error for now if the current instruction is a
		 * no-wait control instruction */
		/* The 80486 manual contradicts itself on this topic, so I use
		 * the following list of such instructions until I can check
		 * on a real 80486: fninit, fnstenv, fnsave, fnstsw, fnstenv,
		 * fnclex. */
		if (!((((code & 0xf803) == 0xe003) ||	/* fnclex, fninit,
							 * fnstsw */
			    (((code & 0x3003) == 0x3001) &&	/* fnsave, fnstcw,
								 * fnstenv, fnstsw */
				((code & 0xc000) != 0xc000))))) {
			/* This is a guess about what a real FPU might do to
			 * this bit: */