Re: ESP corruption bug - what CPUs are affected?

From: Richard B. Johnson
Date: Wed Sep 22 2004 - 15:29:50 EST

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In reply to: Stas Sergeev: "Re: ESP corruption bug - what CPUs are affected?"
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On Thu, 23 Sep 2004, Stas Sergeev wrote:

> Hi,
>
> Richard B. Johnson wrote:
> > What problem is this supposed to fix?
> Richard, it will really help if you read the
> whole thread. I was answering this to Denis
> Vlasenko already - he agreed. Do I have to
> repeat the explanations?
>
> > ESP is __not__ corrupted
> Right, but is not properly restored either,
> while it have to be.
>
> > when returning to protected-mode or a different privilege level.
> It gets "corrupted" (not properly restored)
> exactly when returning to *protected mode*
> from another priv level. Please refer to the
> Intel docs I pointed to in that thread earlier.
>
> > You don't 'return' to protected mode from a virtual-8086 mode,
> Noone was speaking about v86. I don't see why
> you pick that up.
>
> > The so-called bug is that when in real mode or in virtual-8086
> > mode, the high word of ESP is not changed.
> In short: Wrong.
> The complete explanations are easily locateable
> in that thread. And it have nothing to do with
> the real mode either.
>
> > It is not a bug
> > because the high word doesn't even exist when in VM-86 mode!!
> Noone was speaking about v86, sorry. I am bypassing
> that part.
>
> > It is possible to use the 32-bit prefix, when in 16-bit mode,
> That's not about the prefixes either, sorry.
> We were talking about the 32bit PM code.
>
> > Please, somebody from Intel tell these guys to leave the thing
> > alone.
> Thanks many, they already left that alone once:)
> Maybe enough of leaving the bugs alone?
> I have lots of the DOS progs here that do not
> work under dosemu without that patch, and work
> perfectly with it. It should be enough. If
> you need an examples - well, OpenCubicPlayer
> for one. It will start, but crash as soon as
> the music is attempted to play. The patch fixes
> it. Other progs you'll have problems downloading
> anyway, but let me know if you need these.
>
> > I, for one, don't want a bunch of "fixes" that do nothing
> > except consume valuable RAM, making it near impossible to
> > use later versions of Linux in embedded systems.
> Well, my patch is purely in asm. How many
> valueable bytes does it take from you?
> As for performance - 8 asm insns on a generic
> path. Not too much either, as for me.
>

Well DOSEMU uses VM-86 mode. That's how it works. It
creates a virtual 8086 machine, complete with the
required "DOS compatible" virtual BIOS environment.

I use it all the time because I write, amongst other things,
the complete BIOS and startup code for many Intel based
machines.

I run compilers, assemblers, linkers, and editors in that
environment and it works.

Sombody mentions a completely unrelated so-called Intel
bug and next thing you know, there are patches to work-
around the bug???

The bug doesn't exist period. Here is a session in
VM-86 mode., using DOSEMU. It does one hell of a lot
more work than your games.

Script started on Wed Sep 22 16:00:02 2004
# godos
CPU speed set to 2793/1 MHz
Running on CPU=586, FPU=1, rdtsc=1
Linux DOS emulator 0.98.5.0 $Date: 99/01/15 $
Last configured at Wed Mar 24 12:44:16 EST 1999 on linux
This is work in progress.
Please test against a recent version before reporting bugs and problems.
Bugs, Patches & New Code to linux-msdos@xxxxxxxxxxxxxxxx

Starting MS-DOS...

[1;1H[37m[44m
[2;1H
[3;1H
[4;1H
[5;1H 1. Start the TCP/IP Network (NE* B
radley's code) [6;1H 2. Start the TCP/IP Network (3COM Board PCTCP) [7;1H 3. Start the TCP/IP Network (3COM Board ANALOGIC) [8;1H 4. Load NDIS driver only (3COM Board) [9;1H [1m[37m[47m5. Do not load any network[m[37m[44m [10;1H 6. Do not execute any AUTOEXEC.BAT commands [11;1H 7. Start RCCS Host Software [12;1H MS-DOS 6.22 Startup Menu [13;1H Enter a choice: 5ÍÍÍÍÍÍ [14;1H [15;1H [16;1H [17;1H [18;1H [19;1H [20;1H [21;1H [22;1H [23;1H [24;1H [25;1HF5=Bypass startup files F8=Confirm each line of CONFIG.SYS and AUTOEXEC.BAT [N][13;19H[13;27HTime remaining: 04[13;19H[13;20H [25;1H [15;1H
MS-DOS Version 6.22

C:\>cd pbios

C:\PBIOS>make clean

Microsoft (R) Program Maintenance Utility Version 4.07
Copyright (C) Microsoft Corp 1984-1988. All rights reserved.

[37m[40m[3;24r[3;1H[3;24r[24;1H

[3;24r[5;1H[1;25r[23;1H[37m[44m [24;1H if exist *.obj del *.obj [25;1H[37m[40m[1;24r[1;1H[1;24r[24;1H

[1;24r[1;1H[1;25r[22;1H[37m[44m if exist *.bin del *.bin [23;1H if exist *.rom del *.rom [24;1H if exist *.hex del *.hex [25;1H[37m[40m[1;24r[1;1H[1;24r[24;1H

[1;24r[1;1H[1;25r[18;1H[37m[44m if exist *.lis del *.lis [19;1H if exist *.com del *.com [20;1H if exist *.exe del *.exe [21;1H if exist *.oe0 del *.oe0 [22;1H if exist *.oe1 del *.oe1 [23;1H cd tools [24;1H if exist *.obj del *.obj [25;1H[37m[40m[3;24r[3;1H[3;24r[24;1H

[3;24r[5;1H[1;25r[1;1H[37m[44mC:\PBIOS> make clean[18;1H if exist *.bin del *.bin [19;1H if exist *.rom del *.rom [20;1H if exist *.hex del *.hex [21;1H if exist *.com del *.com [22;1H if exist *.exe del *.exe [23;1H cd .. [24;1H [25;1HC:\PBIOS>[25;11Hmake[25;16Hpbios[37m[40m[2;20r[2;1HMMMMMMMMMMMMMMMM[1;25r[1;1H[37m[44m if exist *.obj del *.obj
if exist *.bin del *.bin [3;1H if exist *.rom del *.rom [4;1H if exist *.hex del *.hex [5;1H if exist *.com del *.com [6;1H if exist *.exe del *.exe [7;1H cd .. [8;1H [9;1HC:\PBIOS> make pbios [10;1H [11;1HMicrosoft (R) Program Maintenance Utility Version 4.07 [12;1HCopyright (C) Microsoft Corp 1984-1988. All rights reserved. [13;1H [14;1H [15;1HMAKE : warning U4000: 'TOOLS\IHEX.EXE' : target does not exist [16;1H CD TOOLS [17;1H MAKE TOOLS [21;3H [22;3H
MAKE : warning U4000: 'odeven.exe' : target does not exist[24;3Hcl -W3 odeven.c

[37m[40m[10;16r[10;1HMMMM[1;25r[1;14H[37m[44mcom[7Ccom[2;14Hexe[7Cexe[3;3Hcd .. [4;3H
C:\PBIOS> make pbios [6;3H
Microsoft (R) Program Maintenance Utility Version 4.07
Copyright (C) Microsoft Corp 1984-1988. All rights reserved.

[11;1HMAKE : warning U4000: 'TOOLS\IHEX.EXE' : target does not exist [12;1H CD TOOLS [13;1H MAKE TOOLS [17;3H [19;2HAKE : warning U4000: 'odeven.exe' : target does not exist
cl -W3 odeven.c
Microsoft (R) C Optimizing Compiler Version 6.00A
Copyright (c) Microsoft Corp 1984-1990. All rights reserved.

odeven.c
[37m[40m[2;24r[2;1H[2;24r[24;1H

[2;24r[3;1H[1;25r[1;3H[37m[44m [16;1H [17;1HMicrosoft (R) Segmented-Executable Linker Version 5.13 [18;1HCopyright (C) Microsoft Corp 1984-1991. All rights reserved. [19;1H [20;1HObject Modules [.OBJ]: odeven.obj /farcall [21;1HRun File [odeven.exe]: "odeven.exe" /noi [22;1HList File [NUL.MAP]: NUL [23;1HLibraries [.LIB]: [24;1HDefinitions File [NUL.DEF]: ; [25;1H[37m[40m[3;24r[3;1H[3;24r[24;1H

[3;24r[5;1H[1;25r[2;1H[37m[44m [18;1H [19;1HMAKE : warning U4000: 'fixup.exe' : target does not exist [20;1H cl -W3 fixup.c [21;1HMicrosoft (R) C Optimizing Compiler Version 6.00A [22;1HCopyright (c) Microsoft Corp 1984-1990. All rights reserved. [23;1H [24;1Hfixup.c [25;1H[1;1HDefinitions File [NUL.DEF]: ;[3;24Hfixup.exe' : target does not exist [4;10Hfixup.c

fixup.c [13;24Hfixup.obj /farcall [14;11Hfixup.exe]: "fixup.exe" /noi [19;24Hgetall.exe' : target does not exist[20;10Hgetall.c

getall.c
[3;24Hgetall.exe' : target does not exist[4;10Hgetall.c

getall.c[13;24Hgetall.obj /farcall[14;11Hgetall.exe]: "getall.exe" /noi[19;24Hpci.obj' : target does not exist [20;7HAL -c -W3 -o pci.obj pci.c

pci.c
[37m[40m[2;22r[2;1H[2;22r[22;1H

[2;22r[3;1H[1;25r[1;1H[37m[44m [17;1H [18;1Hpci.c [19;1H [20;1HMAKE : warning U4000: 'pcireg.obj' : target does not exist [21;1H tasm pcireg; [22;1HTurbo Assembler Version 2.0 Copyright (c) 1988, 1990 Borland International [24;1HAssembling file: pcireg.ASM
[37m[40m[3;23r[3;1HMMMMMMMMMMMMMMMMMM[1;25r[1;1H[37m[44mMAKE : warning U4000: 'pci.obj' : target does not exist
cl -AL -c -W3 -o pci.obj pci.c
Microsoft (R) C Optimizing Compiler Version 6.00A [4;1HCopyright (c) Microsoft Corp 1984-1990. All rights reserved. [5;1H [6;1Hpci.c [7;1H [8;1HMAKE : warning U4000: 'pcireg.obj' : target does not exist [9;1H tasm pcireg; [10;1HTurbo Assembler Version 2.0 Copyright (c) 1988, 1990 Borland International [11;1H [12;1HAssembling file: pcireg.ASM [13;1HError messages: None [14;1HWarning messages: None [15;1HPasses: 1 [16;1HRemaining memory: 324k [17;1H [18;1H [19;1HMAKE : warning U4000: 'pci.exe' : target does not exist [20;1H link pci pcireg; [24;1H
[37m[40m[1;24r[1;1H[1;24r[24;1H

[1;24r[1;1H[1;25r[18;1H[37m[44m [19;1HMAKE : warning U4000: 'ihex.exe' : target does not exist [20;1H cl -W3 ihex.c [21;1HMicrosoft (R) C Optimizing Compiler Version 6.00A [22;1HCopyright (c) Microsoft Corp 1984-1990. All rights reserved. [23;1H [24;1Hihex.c [25;1H[37m[40m[14;18r[14;1HMM[1;25r[1;1H[37m[44m [2;3H
MAKE : warning U4000: 'pci.exe' : target does not exist [4;3Hlink pci pcireg;

Microsoft (R) Segmented-Executable Linker Version 5.13
Copyright (C) Microsoft Corp 1984-1991. All rights reserved.
[12C

MAKE : warning U4000: 'ihex.exe' : target does not exist[11;3Hcl -W3 ihex.c[12;2Hicrosoft (R) C Optimizing Compiler Version 6.00A
Copyright (c) Microsoft Corp 1984-1990. All rights reserved.
[15;1Hihex.c [19;1H
Object Modules [.OBJ]: ihex.obj /farcall
Run File [ihex.exe]: "ihex.exe" /noi
List File [NUL.MAP]: NUL
Libraries [.LIB]:
Definitions File [NUL.DEF]: ;
[37m[40m[5;11r[5;1HMMMM[1;25r[3;24H[37m[44mihex.exe' : target does not exist[4;3Hcl -W3 ihex.c
Microsoft (R) C Optimizing Compiler Version 6.00A [6;1HCopyright (c) Microsoft Corp 1984-1990. All rights reserved. [7;1H [8;1Hihex.c [12;1H
Object Modules [.OBJ]: ihex.obj /farcall
Run File [ihex.exe]: "ihex.exe" /noi
List File [NUL.MAP]: NUL
Libraries [.LIB]:
Definitions File [NUL.DEF]: ;
CD ..

MAKE : warning U4000: 'ABIOS.OBJ' : target does not exist
TASM /ml /p /w2 /m2 PBIOS, ABIOS.OBJ, PBIOS.LIS;
Turbo Assembler Version 2.0 Copyright (c) 1988, 1990 Borland International

Assembling file: PBIOS.ASM to ABIOS.OBJ
[37m[40m[2;21r[2;1H[2;21r[21;1H

[2;21r[3;1H[1;25r[11;1H[37m[44mTurbo Assembler Version 2.0 Copyright (c) 1988, 1990 Borland International [12;1H [13;1HAssembling file: PBIOS.ASM to ABIOS.OBJ [14;1HError messages: None [15;1HWarning messages: None [16;1HPasses: 2 [17;1HRemaining memory: 258k [18;1H [19;1H [20;1HMAKE : warning U4000: 'BBIOS.OBJ' : target does not exist [21;1H TASM /ml /p /w2 /m2 /DCOM=1 PBIOS, BBIOS.OBJ; [24;35HB
[37m[40m[1;24r[1;1H[1;24r[24;1H

[1;24r[1;1H[1;25r[17;1H[37m[44mError messages: None [18;1HWarning messages: None [19;1HPasses: 2 [20;1HRemaining memory: 262k [21;1H [22;1H [23;1HMAKE : warning U4000: 'ABIOS.BIN' : target does not exist [24;1H LINK/T ABIOS.OBJ, ABIOS.BIN; [25;1H[37m[40m[6;15r[6;1HMMMMMMM[1;25r[1;1H[37m[44mAssembling file: PBIOS.ASM to ABIOS.OBJ
Error messages: None
Warning messages: None
Passes:[12C2
Remaining memory: 258k
[7;1H [8;1HMAKE : warning U4000: 'BBIOS.OBJ' : target does not exist [9;1H TASM /ml /p /w2 /m2 /DCOM=1 PBIOS, BBIOS.OBJ; [10;1HTurbo Assembler Version 2.0 Copyright (c) 1988, 1990 Borland International [11;1H [12;1HAssembling file: PBIOS.ASM to BBIOS.OBJ [16;1HRemaining memory: 262k

MAKE : warning U4000: 'ABIOS.BIN' : target does not exist
LINK/T ABIOS.OBJ, ABIOS.BIN;

Microsoft (R) Segmented-Executable Linker Version 5.13
Copyright (C) Microsoft Corp 1984-1991. All rights reserved.[24;3H
[37m[40m[2;5r[2;1HM[1;25r[1;1H[37m[44m
Assembling file: PBIOS.ASM to BBIOS.OBJ [6;1HRemaining memory: 262k

MAKE : warning U4000: 'ABIOS.BIN' : target does not exist
LINK/T ABIOS.OBJ, ABIOS.BIN;

Microsoft (R) Segmented-Executable Linker Version 5.13
Copyright (C) Microsoft Corp 1984-1991. All rights reserved.

[12C
MAKE : warning U4000: 'PBIOS.COM' : target does not exist[17;3HLINK/T BBIOS.OBJ, PBIOS.COM;[19;2Hicrosoft (R) Segmented-Executable Linker Version 5.13
Copyright (C) Microsoft Corp 1984-1991. All rights reserved.

MAKE : warning U4000: 'PBIOS.ROM' : target does not exist [24;3HTOOLS\FIXUP ABIOS.BIN PBIOS.ROM
[37m[40m[2;24r[2;1H[2;24r[24;1H

[2;24r[3;1H[1;25r[18;1H[37m[44m [19;1HMAKE : warning U4000: 'PBIOS.HEX' : target does not exist [20;1H TOOLS\IHEX PBIOS.ROM PBIOS.HEX 0 20 Y [21;1HIHEX V2.00 Analogic Software Tools [22;1H [23;1HReading from file PBIOS.ROM, writing to file PBIOS.HEX ... [24;1HStarting address (hex) 0000, block length (hex) 20 [25;1H[37m[40m[1;25r[1;1H[1;25r[25;1H
[1;25r[1;1H[1;25r[25;1H[37m[44mC:\PBIOS> [25;11Hback
[37m[40m[m[0m[m
[K
(B(B

#
#
#
#
# exit
Script done on Wed Sep 22 16:00:39 2004

Even Linux 32-bit `script` works when I am in VM-86 mode.

Cheers,
Dick Johnson
Penguin : Linux version 2.4.26 on an i686 machine (5570.56 BogoMips).
Note 96.31% of all statistics are fiction.

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Next message: Dave Aubin: "Is there a user space pci rescan method?"
Previous message: Nivedita Singhvi: "Re: The ultimate TOE design"
In reply to: Stas Sergeev: "Re: ESP corruption bug - what CPUs are affected?"
Next in thread: Petr Vandrovec: "Re: ESP corruption bug - what CPUs are affected?"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]