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diff --git a/binary/objdump.html b/binary/objdump.html index e61f55a..e97b853 100644 --- a/binary/objdump.html +++ b/binary/objdump.html @@ -158,6 +158,39 @@ <p>For example <code>.plt</code> section:</p> <pre><code class="language-markdown"> objdump -j .plt -d <elf> </code></pre> +<h2 id="example-disassemble-raw-binary"><a class="header" href="#example-disassemble-raw-binary">Example: disassemble raw binary</a></h2> +<p>This can be helpful for example as a cheap analysis tool when toying with JIT +generating code. We could just write thee binary code buffer to a file and +disassemble with <code>objdump</code>.</p> +<p>To re-create that case, we just assemble and link some ELF file and then create +a raw binary of the text section with <code>objcopy</code>.</p> +<pre><code class="language-x86asm"># file: test.s +.section .text, "ax" + +.global _start +_start: + xor %rax, %rax + mov $0x8, %rax +1: + cmp $0, %rax + je 2f + dec %rax + jmp 1b +2: + # x86-64 exit(2) syscall + mov $0, %rdi + mov $60, %rax + syscall +</code></pre> +<pre><code class="language-bash"># Assemble & link. +as -o test.o test.s +ld -o test test.o testc.o +# ELF -> binary (only take .text section). +objcopy -O binary --only-section .text test test-bin + +# Disassemble raw binary. +objdump -D -b binary -m i386:x86-64 test-bin +</code></pre> </main> |