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Diffstat (limited to 'src')
-rw-r--r-- | src/binary/objdump.md | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/src/binary/objdump.md b/src/binary/objdump.md index 636db3f..a76a327 100644 --- a/src/binary/objdump.md +++ b/src/binary/objdump.md @@ -16,3 +16,41 @@ For example `.plt` section: ```markdown objdump -j .plt -d <elf> ``` + +## Example: disassemble raw binary +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 `objdump`. + +To re-create that case, we just assemble and link some ELF file and then create +a raw binary of the text section with `objcopy`. + +```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 +``` +```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 +``` |