Lab46 Wiki

PNC the 3

Alright, so PNC3!! So guys the goal is to create a primereg in assembly. It should be possible with our current knowledge in assembly. If you would like, and just primereg isn't enough for you by all means go further and do things such as:

primeregb
primeregs
primeregbs
primerega
primeregba
primeregboa

good luck guys! Have fun!

compiling

nasm -f elf64 -o pnc3.o pnc3.asm 
ld -o pnc3 pnc3.o

gdb commands

show registers
info registers (shows info on register)
- this can be shortened as an example to: i r eax
set disassembly-flavor intel (sets assembly flavor up to intel)
break _start: (start of program, go step by step from here)
layout asm
ni - next instruction
si - step instruction

example of displaying registers:

break _start \\Breakpoint 1, 0x0000000000400080 in _start ()
(gdb) display/x $rax
1: /x $rax = 0x0
(gdb) display/x $rbx
2: /x $rbx = 0x0
(gdb) display/x $rcx
3: /x $rcx = 0x0
(gdb) display/x $rip
4: /x $rip = 0x400080
(gdb)
si

Helpful sources:

Register usage: Take note of registers r12-r15