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HardenedBSD/sys/gnu/i386/fpemul/fpu_entry.c
Jordan K. Hubbard 1c28e35f68 Commit a whole cluster of last minute critical (and one cosmetic) fixes 
from David Greenman, Bruce Evans and Julian Elischer.

They are:

[vnode pager - David/Bruce]:
  The following patch fixes a problem where some data could be lost in a
delayed-write buffer if the cached buffer was larger than a page. This fix was
provided by Bruce Evans and modified slightly by me.

[st.c - Julian]:
  My fix for "bad request, must be between 0 and 0"

RTFS if you're interested).

[gnu/fpemul - David/Bruce]:
  These changes fix single stepping of emulated FPU instructions.
Previously, the instruction after an emulated instruction was
executed without causing a SIGTRAP ...

The also fix the initial control word being different for the
GPL emulator (it is still wrong for the old emulator) and remove
an unnecessary panic when emulation is not configured (I hope at
least init, sh and reboot will run without floating point.  I
remember only df and mkfs being broken by the lack of FP in 0.0).

[Various fixes described below - Bruce/David]:
sys/i386/boot/boot2.S:
        Yet another attempt to propagate the correct fix for 16 vs
        32-bit mode bugs.  [verified]

sys/i386/i386/db_interface.c:
        Protect against reentering Debugger().

sys/kern/kern_time.c:
        Don't allow 'time.tv_usec == 0' except at clock interrupts.

sys/pcfs/pcfs_fat.c:
        Make it compile without -O.

sys/scsi/sd.c:
        Fix as posted to some freebsd mailing list.
        (changes the order of the assignment of "sectors" because it earlier
          value is needed first -DG)

sys/vm/vm_glue.c:
        Fix stale comments and verbose code.

sys/vm/vm_mmap.c
        Fix off by 1 errors and verbose code.

[From Nate - cosmetic but non-intrusive and useful enough to go in]
sys/i386/isa/isa.c:
Appended you'll find a patch to the NMI error log routine in isa/isa.c.
The below patch just adds some additional information when an NMI occurs
which can help debug the hardware problem.
1994-06-22 05:52:25 +00:00

484 lines
16 KiB
C
Raw Blame History

/*
* 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 billm@vaxc.cc.monash.edu.au
* 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.
*
* $Id: fpu_entry.c,v 1.3 1994/06/10 07:44:22 rich 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 "param.h"
#include "systm.h"
#include "proc.h"
#include "machine/cpu.h"
#include "machine/pcb.h"
#include "fpu_emu.h"
#include "fpu_system.h"
#include "exception.h"
#include "control_w.h"
#include "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);
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 & STRC)
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: */
/* status_word &= ~SW_Summary; ****/
/* We need to simulate the action of the kernel to FPU
* interrupts here. Currently, the "real FPU" part of
* the kernel (0.99.10) clears the exception flags,
* sets the registers to empty, and passes information
* back to the interrupted process via the cs selector
* and operand selector, so we do the same. */
do_the_FPU_interrupt:
cs_selector &= 0xffff0000;
cs_selector |= (status_word & ~SW_Top) | ((top & 7) << SW_Top_Shift);
operand_selector = tag_word();
status_word = 0;
top = 0;
{
int r;
for (r = 0; r < 8; r++) {
regs[r].tag = TW_Empty;
}
}
REENTRANT_CHECK(OFF);
math_abort(SIGFPE);
}
}
FPU_entry_eip = FPU_ORIG_EIP = FPU_EIP;
if ((code & 0xff) == 0x66) { /* size prefix */
FPU_EIP++;
REENTRANT_CHECK(OFF);
code = fuword((u_int *) FPU_EIP);
REENTRANT_CHECK(ON);
}
FPU_EIP += 2;
FPU_modrm = code >> 8;
FPU_rm = FPU_modrm & 7;
if (FPU_modrm < 0300) {
/* All of these instructions use the mod/rm byte to get a data
* address */
get_address(FPU_modrm);
if (!(code & 1)) {
unsigned short status1 = status_word;
FPU_st0_ptr = &st(0);
FPU_st0_tag = FPU_st0_ptr->tag;
/* Stack underflow has priority */
if (NOT_EMPTY_0) {
switch ((code >> 1) & 3) {
case 0:
reg_load_single();
break;
case 1:
reg_load_int32();
break;
case 2:
reg_load_double();
break;
case 3:
reg_load_int16();
break;
}
/* No more access to user memory, it is safe
* to use static data now */
FPU_st0_ptr = &st(0);
FPU_st0_tag = FPU_st0_ptr->tag;
/* NaN operands have the next priority. */
/* We have to delay looking at st(0) until
* after loading the data, because that data
* might contain an SNaN */
if ((FPU_st0_tag == TW_NaN) ||
(FPU_loaded_data.tag == TW_NaN)) {
/* Restore the status word; we might
* have loaded a denormal. */
status_word = status1;
if ((FPU_modrm & 0x30) == 0x10) {
/* fcom or fcomp */
EXCEPTION(EX_Invalid);
setcc(SW_C3 | SW_C2 | SW_C0);
if (FPU_modrm & 0x08)
pop(); /* fcomp, so we pop. */
} else
real_2op_NaN(FPU_st0_ptr, &FPU_loaded_data, FPU_st0_ptr);
goto reg_mem_instr_done;
}
switch ((FPU_modrm >> 3) & 7) {
case 0: /* fadd */
reg_add(FPU_st0_ptr, &FPU_loaded_data, FPU_st0_ptr, control_word);
break;
case 1: /* fmul */
reg_mul(FPU_st0_ptr, &FPU_loaded_data, FPU_st0_ptr, control_word);
break;
case 2: /* fcom */
compare_st_data();
break;
case 3: /* fcomp */
compare_st_data();
pop();
break;
case 4: /* fsub */
reg_sub(FPU_st0_ptr, &FPU_loaded_data, FPU_st0_ptr, control_word);
break;
case 5: /* fsubr */
reg_sub(&FPU_loaded_data, FPU_st0_ptr, FPU_st0_ptr, control_word);
break;
case 6: /* fdiv */
reg_div(FPU_st0_ptr, &FPU_loaded_data, FPU_st0_ptr, control_word);
break;
case 7: /* fdivr */
if (FPU_st0_tag == TW_Zero)
status_word = status1; /* Undo any denorm tag,
* zero-divide has
* priority. */
reg_div(&FPU_loaded_data, FPU_st0_ptr, FPU_st0_ptr, control_word);
break;
}
} else {
if ((FPU_modrm & 0x30) == 0x10) {
/* The instruction is fcom or fcomp */
EXCEPTION(EX_StackUnder);
setcc(SW_C3 | SW_C2 | SW_C0);
if (FPU_modrm & 0x08)
pop(); /* fcomp, Empty or not,
* we pop. */
} else
stack_underflow();
}
} else {
load_store_instr(((FPU_modrm & 0x38) | (code & 6)) >> 1);
}
reg_mem_instr_done:
data_operand_offset = (unsigned long) FPU_data_address;
} else {
/* None of these instructions access user memory */
unsigned char instr_index = (FPU_modrm & 0x38) | (code & 7);
FPU_st0_ptr = &st(0);
FPU_st0_tag = FPU_st0_ptr->tag;
switch (type_table[(int) instr_index]) {
case _NONE_: /* also _REGIc: _REGIn */
break;
case _REG0_:
if (!NOT_EMPTY_0) {
stack_underflow();
goto FPU_instruction_done;
}
break;
case _REGIi:
if (!NOT_EMPTY_0 || !NOT_EMPTY(FPU_rm)) {
stack_underflow_i(FPU_rm);
goto FPU_instruction_done;
}
break;
case _REGIp:
if (!NOT_EMPTY_0 || !NOT_EMPTY(FPU_rm)) {
stack_underflow_i(FPU_rm);
pop();
goto FPU_instruction_done;
}
break;
case _REGI_:
if (!NOT_EMPTY_0 || !NOT_EMPTY(FPU_rm)) {
stack_underflow();
goto FPU_instruction_done;
}
break;
case _PUSH_: /* Only used by the fld st(i) instruction */
break;
case _null_:
Un_impl();
goto FPU_instruction_done;
default:
EXCEPTION(EX_INTERNAL | 0x111);
goto FPU_instruction_done;
}
(*st_instr_table[(int) instr_index]) ();
}
FPU_instruction_done:
ip_offset = FPU_entry_eip;
bswapw(code);
*(1 + (unsigned short *) &cs_selector) = code & 0x7ff;
#ifdef DEBUG
REENTRANT_CHECK(OFF);
emu_printall();
REENTRANT_CHECK(ON);
#endif /* DEBUG */
#ifdef LOOKAHEAD_LIMIT
if (--lookahead_limit)
#endif
if (FPU_lookahead) {
unsigned char next;
/* (This test should generate no machine code) */
while (1) {
REENTRANT_CHECK(OFF);
next = fubyte((u_char *) FPU_EIP);
REENTRANT_CHECK(ON);
if (((next & 0xf8) == 0xd8) || (next == 0x9b)) { /* fwait */
goto do_another_FPU_instruction;
} else
if (next == 0x66) { /* size prefix */
REENTRANT_CHECK(OFF);
next = fubyte((u_char *) (FPU_EIP + 1));
REENTRANT_CHECK(ON);
if ((next & 0xf8) == 0xd8) {
FPU_EIP++;
goto do_another_FPU_instruction;
}
}
break;
}
}
REENTRANT_CHECK(OFF);
return (0); /* --pink-- */
}
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