CODEWITHSUNDEEP
assemblyatt
Temp
Temp

Reputation: 43

How to view machine code?

I've written a program in assembly (at&t syntax) and I want to see how the machine code looks. This is how I get executable code: 

as -g -o p1.o p1.s --32 -gstabs
ld -o p1 p1.o -m elf_i386

Upvotes: 3

Views: 3290

Answers (1)

David Hoelzer
David Hoelzer

Reputation: 16331

Assuming that you are on a Linux or BSD platform (based on the fact that you're using as), you might want to try objdump.

objdump -d <binary file> will disassemble the object file, showing you machine code hex bytes on the left and the disassembled matching assembly mnemonics on the right. Here's an example:

$ objdump -d factorial

factorial:     file format elf64-x86-64

Disassembly of section .init:

00000000004003f0 :
  4003f0:   48 83 ec 08             sub    $0x8,%rsp
  4003f4:   e8 73 00 00 00          callq  40046c
  ..
Disassembly of section .plt:

0000000000400408 :
  400408:   ff 35 e2 0b 20 00       pushq  0x200be2(%rip)        # 600ff0
  40040e:   ff 25 e4 0b 20 00       jmpq   *0x200be4(%rip)        # 600ff8
  400414:   0f 1f 40 00             nopl   0x0(%rax)

objdump is a part of the binutils package on Linux platforms.

Upvotes: 6

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