Segfault on ioperm

Segfault on ioperm

[joy merwin monteiro]

Hi,

I had been here before, I can't figure out why the code isnt working.

global _start

port equ 378h
stat equ port+1
ctrl equ port+2

section .text
_start:
    
    mov eax,101
    mov ebx,port
    mov ecx,3
    mov edx,port
    int 80h
    mov dx,port
    mov al,0xff
    out 378h,al  <----- segfault here
    mov eax,1
    int 0x80

Any help/ pointers?

Thanks,

Joy.M.Monteiro
-- 
people always turn away,
from the eyes of a stranger...
Afraid to know
what lies behind the stare.......
    --QueensRyche

Re: Segfault on ioperm

[Richard Cooper]

> Hi,
>
> I had been here before, I can't figure out why the code isnt working.

>     mov eax,101
>     mov ebx,port
>     mov ecx,3
>     mov edx,port
>     int 80h

You really should check the return value here.  I imagine the call is failing.  In particular, you need to have root access, and I believe that edx should actually be 1.

If you're just hoping to control a device you've connected to your parallel port, you might try designing it so that it can work just from the output byte bits, on pins 2 through 9, if that's possible with what you are doing.  You'll have to connect pin 11 to 23 and 12 to 24 so that the busy and out of paper signals go away, otherwise the lp driver will block your process on writes thinking the printer is busy or out of paper.  Then whatever byte you write to the lp driver will stay on those pins until you write another.

Re: Segfault on ioperm

[Jan Wagemakers]

joy merwin monteiro <joy.merwin@gmail.com> schreef:

>     mov dx,port
>     mov al,0xff
>     out 378h,al  <----- segfault here

I think that this should be :

	out dx, al
	
>     mov eax,1
>     int 0x80
> Any help/ pointers?

I hope this helps you. Good luck!


-- 
Met vriendelijke groetjes         - Jan Wagemakers -

... RFS: picprog: Microchip PIC serial programmer software (GPL)
    Deb-package is available at <http://www.janw.easynet.be/picprog.html>
    

Re: Segfault on ioperm

[joy merwin monteiro]

Hi,

I tried the same program on a different distro (SW 10).
possibly ld on woody is broken (being so old and all..)
it works fine on SW .....

Any comments/suggestions?

Thanks for the help,

Joy.M.Monteiro

On Thu, 20 Jan 2005 16:26:00 +0100, Jan Wagemakers <janw@easynet.be> wrote:
> joy merwin monteiro <joy.merwin@gmail.com> schreef:
> 
> >     mov dx,port
> >     mov al,0xff
> >     out 378h,al  <----- segfault here
> 
> I think that this should be :
> 
>         out dx, al
> 
> >     mov eax,1
> >     int 0x80
> > Any help/ pointers?
> 
> I hope this helps you. Good luck!
> 
> --
> Met vriendelijke groetjes         - Jan Wagemakers -
> 
> ... RFS: picprog: Microchip PIC serial programmer software (GPL)
>     Deb-package is available at <http://www.janw.easynet.be/picprog.html>
> 
> -
> To unsubscribe from this list: send the line "unsubscribe linux-assembly" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 


-- 
people always turn away,
from the eyes of a stranger...
Afraid to know
what lies behind the stare.......
    --QueensRyche

Re: Segfault on ioperm

[Frank Kotler]

joy merwin monteiro wrote:
> 
> Hi,
> 
> I had been here before, I can't figure out why the code isnt working.

Seems like everybody's got a different idea what's wrong...
I might as well throw in my wild guess, too :)

> global _start
> 
> port equ 378h
> stat equ port+1
> ctrl equ port+2
> 
> section .text
> _start:
> 
>     mov eax,101
>     mov ebx,port
>     mov ecx,3

This is the number of ports you're enabling, right?

>     mov edx,port

And this should be the "turn-on" value... I imagine you want
"3" here, too, for "in" and "out" permissions...

>     int 80h

Check the returned value here, as Richard says, if signed,
bail out.

>     mov dx,port
>     mov al,0xff
>     out 378h,al  <----- segfault here

"out dx, al", as Jan suggests...

>     mov eax,1
>     int 0x80
> 
> Any help/ pointers?

Odd that it should work on a different distro... If you
suspect ld, grab newer binutils... Different permissions
setup would be more likely, I would think... But check that
return value - it should tell the tale. (assume you know
that -ERRNO is in eax, not -1 and ERRNO in errno, as man 2
says...)

Best,
Frank

Re: Segfault on ioperm

[joy merwin monteiro]

On Thu, 20 Jan 2005 13:40:18 -0500, Frank Kotler <fbkotler@comcast.net> wrote:
> joy merwin monteiro wrote:
> >
> > Hi,
> >
> > I had been here before, I can't figure out why the code isnt working.
> 
> Seems like everybody's got a different idea what's wrong...
> I might as well throw in my wild guess, too :)
> 
> > global _start
> >
> > port equ 378h
> > stat equ port+1
> > ctrl equ port+2
> >
> > section .text
> > _start:
> >
> >     mov eax,101
> >     mov ebx,port
> >     mov ecx,3
> 
> This is the number of ports you're enabling, right?
> 
> >     mov edx,port
> 
> And this should be the "turn-on" value... I imagine you want
> "3" here, too, for "in" and "out" permissions...

No idea, Just used the code available on http://www.janw.easynet.be/eng.html
as a reference. it works fine, so......
> 
> >     int 80h
> 
> Check the returned value here, as Richard says, if signed,
> bail out.
> 
> >     mov dx,port
> >     mov al,0xff
> >     out 378h,al  <----- segfault here
> 
> "out dx, al", as Jan suggests...

However, Jan's  musice speaker on the site above uses
"out 43h,al"

Corrected that :-(
> 
> >     mov eax,1
> >     int 0x80
> >
> > Any help/ pointers?
> 
> Odd that it should work on a different distro... If you
> suspect ld, grab newer binutils... Different permissions
> setup would be more likely, I would think... But check that
> return value - it should tell the tale. (assume you know
> that -ERRNO is in eax, not -1 and ERRNO in errno, as man 2
> says...)

Thanks for the pointers.....

Joy.M.Monteiro
> 
> Best,
> Frank
> 


-- 
people always turn away,
from the eyes of a stranger...
Afraid to know
what lies behind the stare.......
    --QueensRyche

Re: Segfault on ioperm

[Frank Kotler]

joy merwin monteiro wrote:

> > >     mov eax,101
> > >     mov ebx,port
> > >     mov ecx,3
> >
> > This is the number of ports you're enabling, right?
> >
> > >     mov edx,port
> >
> > And this should be the "turn-on" value... I imagine you want
> > "3" here, too, for "in" and "out" permissions...
> 
> No idea, Just used the code available on http://www.janw.easynet.be/eng.html
> as a reference. it works fine, so......

Yup. I learn a lot from that page, too. Not "obsolete" at
all, IMO, and your English is fine, too! Thanks, Jan!

In this case, "man 2 ioperm" differs - says "turn on value"
in edx (well... it doesn't say edx...)

> > >     out 378h,al  <----- segfault here
> >
> > "out dx, al", as Jan suggests...
> 
> However, Jan's  musice speaker on the site above uses
> "out 43h,al"

Unless I'm mistaken, you can use an "immediate" value for
in/out - but only for the first 255 ports. If the value
exceeds a byte (as 378h does), you have to use dx.

In case it would be of interest to you, or anybody, I'll
include my simple "beep the speaker" example. I make no
claim that this is "right" (certainly not "elegant"), but it
"seems to work". The "delay" routine, for example,
special-cases a duration of 1 (since I want 0 for an
end-of-data marker, "no delay" is 1). This "special case"
should be handled in the "main" part of the code, leaving
the "delay" subroutine more "generic" - just haven't gotten
around to changing it. I'm sure there are other things, too
- any feedback welcome. Since the port numbers are small,
this *does* use immediates on in/out...

Good luck,
Frank


; Plays a tune, of sorts - sound, anyway.
; It is said that I'm not artistic.
;
; nasm -f elf [-g] play.asm
; ld [-s] -o play play.o
;
; to be able to run without being root:
; as root, "chown root:root play" "chmod +s play"

section .text
global _start
_start:
    nop      ; parking place for gdb

    mov eax, 101   ; sys_ioperm
    mov ebx, 42h   ; starting port
    mov ecx, 20h   ; how many ports
    mov edx, 3     ; read/write
    int 80h

    test eax, eax
    jns okay_ioperm
    neg eax
    call showeax
    mov ebx, eax
    jmp exit

okay_ioperm:

                                ; set up PIT
    mov al, 10111110b
           ;.......|------ binary 16-bit counter
           ;....|||------- square wave generator
           ;..||---------- r/w bits 0-7, then 8-15
           ;||------------ select counter 2
    out 43h, al

    mov esi, melody

playit_sam:                 ; if she can take it, so can I.
    in al, 61h              ; enable speaker
    or al, 00000011b
          ;.......|------- enable speaker on timer 2 gate
          ;......|-------- enable speaker data
    out 61h, al

    lodsd                       ; get a note
    or eax, eax                 ; check for zero
    jz egress                   ; coda

    out 42h, al                 ; play it
    mov al, ah
    out 42h ,al

    lodsd                       ; for this long
    call delay

    in al, 61h                  ; Turn Speaker OFF
    and al, 11111100b
    out 61h, al

    lodsd                       ; for this long
    call delay

    jmp short playit_sam        ; play more

egress:
    in al, 61h
    and al, 0FCh                ; Turn Speaker OFF. Please.
    out 61h, al

    mov eax, 101   ; sys_ioperm
    mov ebx, 42h
    mov ecx, 20h
    mov edx, 0     ; give back ports
    int 80h

    test eax, eax
    jns okay_exit
    neg eax
    call showeax
    mov ebx, eax
    jmp exit

okay_exit:

    xor ebx, ebx
exit:
    mov eax, 1     ; sys_exit
    int 80h
;------------------

;------------------
delay:
    push ebx
    push ecx

    cmp eax, byte 1
    jz .no_delay

    xor ebx, ebx
.check_ns
    cmp eax, 1000000000   ; limit for nanosleep 999999999
ns...
    jb .okay_ns
    sub eax, 1000000000
    inc ebx
    jmp short .check_ns
.okay_ns

    push eax     ; set up a time_spec structure on the stack
    push ebx

.take_a_nap
    mov eax, 162    ; sys_nanosleep
    mov ebx, esp    ; same structure for "request"
    mov ecx, esp    ; and "remaining" - does this work?
    int 80h
    cmp eax, -4     ; -EINTR
    jz .take_a_nap

    add esp, byte 8     ; remove time_spec "structure"

.no_delay:
    pop ecx
    pop ebx
    ret
;------------------

;-----------------------------------
; showeax - prints a decimal representation of eax to stdout
; expects - number to print in eax
; returns - nothing
;------------------------------------
showeax:
    pushad

    xor edi, edi     ; counter
    mov esi, 10      ; divide by ten

    push esi         ; double as LF :)
    inc edi
.top
    xor edx, edx     ; zero edx for the divide
    div esi          ; quotient in eax, remainder in edx
    add dl, '0'      ; convert number to ascii char
    push edx         ; save it
    inc edi          ; bump counter
    or eax, eax      ; is quotient zero?
    jnz .top         ; if not, do more

.print
    mov eax, 4       ; sys_write
    mov ebx, 1       ; stdout
    mov ecx, esp     ; character's on the stack
    mov edx, 1       ; just one
    int 80h          ; do it
    pop edx          ; get rid of the character we've
printed
    dec edi          ; decrement counter
    jnz .print       ; 'til done

    popad
    ret
;-----------------------

section .data

; Some equates, for your compositional assistance
; It is said that I'm not artistic.

    A0 equ 21728
    B0 equ 19328
    C0 equ 18244
    D0 equ 16144
    E0 equ 14080
    F0 equ 13668
    G0 equ 12176
    A1 equ 10864
    B1 equ 9664
    C1 equ 9122
    D1 equ 8072
    E1 equ 7040
    F1 equ 6834
    G1 equ 6088
    A2 equ 5432
    B2 equ 4832
    C2 equ 4561
    D2 equ 4063
    E2 equ 3520
    F2 equ 3417
    G2 equ 3044
    A3 equ 2712
    B3 equ 2416
    C3 equ 2280
    D3 equ 2032
    E3 equ 1810
    F3 equ 1708
    G3 equ 1522
    A4 equ 1356
    B4 equ 1208
    C4 equ 1140
    D4 equ 1016
    E4 equ 905
    F4 equ 854
    G4 equ 762
    A5 equ 678
    B5 equ 604
    C5 equ 558

; Some "durations" for sys_nanosleep
    Z equ 1
    S equ 60000000
    Q equ 120000000
    P equ 240000000
    R equ 480000000
    L equ 1920000000

; The opus itself.
;
; It is said that I'm not artistic.
;
; Format is "note", "duration", "pause", "note", ... , 0
; Write your own!

melody:

       dd G2, P, Z, E2, Q, Z, G2, Q, Q, G1, Q, Q
       dd G1, Q, Q, C2, Q, Q, B2, Q, Z, C2, Q, Z
       dd D2, Q, Q, G2, Q, Q, A3, Q, Z, G2, Q, Z
       dd A3, Q, Q, A2, Q, Q, A2, Q, Q, G2, Q, Q
       dd E2, Q, Z, G2, Q, Z, F2, Q, Z
       dd E2, Q, Z, D2, Q, Q, F2, Q, Z, G2, Q, Z
       dd A3, Q, Z, G2, Q, Z, F2, Q, Z, E2, Q, Z
       dd F2, Q, Z, E2, Q, Z, D2, Q, Z, B2, Q, Z
       dd C2, Q, Z, D2, Q, Z, E2, Q, Z, C2, Q, Z
       dd D2, Q, Q, G3, Q, Z, F3, Q, Z, E3, Q, Z
       dd D3, Q, Z, C3, Q, Z, B3, Q, Z, A3, Q, Z
       dd B3, Q, Z, C3, Q, Z, D3, Q, Z, B3, Q, Q
       dd G0, Q, Q, G0, R, Z, 0

Re: Segfault on ioperm

[Jan Wagemakers]

joy merwin monteiro <joy.merwin@gmail.com> schreef:

>>>     mov dx,port
>>>     mov al,0xff
>>>     out 378h,al  <----- segfault here
>> "out dx, al", as Jan suggests...
> However, Jan's  musice speaker on the site above uses
> "out 43h,al"

This is how OUT works :

 | OUT - Output Data to Port
 |
 |        Usage:  OUT     port,accum
 |        Modifies flags: None
 |              
 |        Transfers byte in AL,word in AX or dword in EAX to the specified
 |        hardware port address.  If the port number is in the range of 0-255
 |        it can be specified as an immediate.  If greater than 255 then the
 |        port number must be specified in DX.  Since the PC only decodes 10
 |        bits of the port address, values over 1023 can only be decoded by
 |        third party vendor equipment and also map to the port range 0-1023.

So, if port > 255 then use dx ;-)


-- 
Met vriendelijke groetjes         - Jan Wagemakers -

 - Debian GNU/Linux 3.1 - Up : 25 days 

Re: Segfault on ioperm

[Jan Wagemakers]

Frank Kotler <fbkotler@comcast.net> schreef:

> Yup. I learn a lot from that page, too. Not "obsolete" at
> all, IMO, and your English is fine, too! Thanks, Jan!

:-)

> ; Plays a tune, of sorts - sound, anyway.
> ; It is said that I'm not artistic.

Nice example...


-- 
Met vriendelijke groetjes         - Jan Wagemakers -

 - Debian GNU/Linux 3.1 - Up : 25 days 

Re: Segfault on ioperm

[joy merwin monteiro]

I got it.....
Thanks a lot for all the help.

regards,
Joy.M.Monteiro


On Sun, 23 Jan 2005 09:17:22 +0100, Jan Wagemakers <janw@easynet.be> wrote:
> joy merwin monteiro <joy.merwin@gmail.com> schreef:
> 
> >>>     mov dx,port
> >>>     mov al,0xff
> >>>     out 378h,al  <----- segfault here
> >> "out dx, al", as Jan suggests...
> > However, Jan's  musice speaker on the site above uses
> > "out 43h,al"
> 
> This is how OUT works :
> 
>  | OUT - Output Data to Port
>  |
>  |        Usage:  OUT     port,accum
>  |        Modifies flags: None
>  |
>  |        Transfers byte in AL,word in AX or dword in EAX to the specified
>  |        hardware port address.  If the port number is in the range of 0-255
>  |        it can be specified as an immediate.  If greater than 255 then the
>  |        port number must be specified in DX.  Since the PC only decodes 10
>  |        bits of the port address, values over 1023 can only be decoded by
>  |        third party vendor equipment and also map to the port range 0-1023.
> 
> So, if port > 255 then use dx ;-)
> 
> --
> Met vriendelijke groetjes         - Jan Wagemakers -
> 
>  - Debian GNU/Linux 3.1 - Up : 25 days
> -
> To unsubscribe from this list: send the line "unsubscribe linux-assembly" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 


-- 
people always turn away,
from the eyes of a stranger...
Afraid to know
what lies behind the stare.......
    --QueensRyche