32 bit assembly code doesn't work on 64 bit

vikramaditya · #1 08-Jan-2009, 00:33

Hi,

The code snippet below works for Linux 32 bit but does NOT work for Linux 64 bit :

Code:

        
        movl    %edi, -4(%rbp)
        movq    %rsi, -16(%rbp)
        movl    $.LC0, %edi
        call    puts
        mov $1447909480,%eax
        mov $10,%ecx
        mov $22104,%edx
        inl (%dx)
        movl    $.LC1, %edi
        call    puts
        leave
        ret

If i change the position of print command (print command below) to print just before IN(inl) instruction, the code works.

Code:

movl    $.LC0, %edi
call    puts

The below code works on Linux 64 bit, the print command place is changed. It is moved just above the IN(inl) command.

Code:

        movl    %edi, -4(%rbp)
        movq    %rsi, -16(%rbp)
        mov $1447909480,%eax
        mov $10,%ecx
        mov $22104,%edx
        movl    $.LC0, %edi
        call    puts
        inl (%dx)
        movl    $.LC1, %edi
        call    puts
        leave
        ret

Can any one tell me how can solve this problem ( i dont want to use print command to make the code work) and why is this happening.

For the reference complete assembly file is attached (It works on Linux 32 bit).
Thanks

Howard_L · #2 08-Jan-2009, 16:49

I presume you obtained that code by using something like:

Code:

gcc -S  yourfile.c

Could you post the C code as well?
I do not have a 64 bit system so can't be of much help (even if I did I wouldn't be of much help)
I would run the program within gdb and see what exactly is going on (and not).

As you can tell this forum does not get a lot of traffic.
Did you consider posting the C code which fails on the C forum which does?
Also tell what exactly happens when the program is successful and when it fails.

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32 bit assembly code doesn't work on 64 bit

Re: 32 bit assembly code doent work on 64 bit