How to make x32 objects and executable?

flat assembler
Message board for the users of flat assembler.

Index > Linux > How to make x32 objects and executable?

Author

Thread

Jin X

Joined: 06 Mar 2004
Posts: 133
Location: Russia

Jin X 12 Apr 2017, 08:26

"format ELF executable 3" makes x86 executable
"format ELF64 executable 3" makes x64 executable
But how can I make x32 (x64 with 32-bit pointers) execetables?
https://en.wikipedia.org/wiki/X32_ABI

p.s. What does mean "3" after "executable" is these lines?

12 Apr 2017, 08:26

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8357
Location: Kraków, Poland

Tomasz Grysztar 12 Apr 2017, 09:58

It should be an ELF file with class ELFCLASS32 and machine EM_X86_64. fasm's "format ELF" is always ELFCLASS32/EM_386 and "format ELF64" is always ELFCLASS64/EM_X86_64. But you can experiment with the ELF formatting macros in fasmg, since they allow to set up these properties freely:

Code:

ELF.Settings.Class = ELFCLASS32
ELF.Settings.Machine = EM_X86_64
ELF.Settings.ABI = ELFOSABI_LINUX
include 'format/elfexe.inc'
include 'x64.inc'
use64

Note that the value of "ELFOSABI_LINUX" constant is 3 and this is the value in "format ELF executable 3" clause.

12 Apr 2017, 09:58

Jin X

Joined: 06 Mar 2004
Posts: 133
Location: Russia

Jin X 13 Apr 2017, 08:30

Thanks!
But why don't you make "format ELFx32" support in original fasm?

13 Apr 2017, 08:30

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8357
Location: Kraków, Poland

Tomasz Grysztar 13 Apr 2017, 11:17

With fasmg's macros it is easier to test such things. If we test and make sure that changing these values is enough, I may try to implement it into fasm.

13 Apr 2017, 11:17

Jin X

Joined: 06 Mar 2004
Posts: 133
Location: Russia

Jin X 13 Apr 2017, 12:38

You may compare headers of x64 and x32 programs made by 'as'+'ld' or 'nasm' to be sure or to find other differences... Smile

13 Apr 2017, 12:38

Tomasz Grysztar

Joined: 16 Jun 2003
Posts: 8357
Location: Kraków, Poland

Tomasz Grysztar 13 Apr 2017, 15:53

Jin X wrote:

You may compare headers of x64 and x32 programs made by 'as'+'ld' or 'nasm' to be sure or to find other differences...

I may but I cannot say how soon that may happen. Wink

13 Apr 2017, 15:53

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20430
Location: In your JS exploiting you and your system

revolution 20 Feb 2019, 09:09

See here for a working example.

20 Feb 2019, 09:09

< Last Thread | Next Thread >

Forum Rules:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum