stage0/Linux Bootstrap/exec_enable.s

56 lines
1.6 KiB
ArmAsm

## Copyright (C) 2016 Jeremiah Orians
## This file is part of stage0.
##
## stage0 is free software: you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published by
## the Free Software Foundation, either version 3 of the License, or
## (at your option) any later version.
##
## stage0 is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
## GNU General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with stage0. If not, see <http://www.gnu.org/licenses/>.
.text # section declaration
# we must export the entry point to the ELF linker or loader.
# They convientionally recognize _start as their entry point.
# Use ld -e main to override the default if you wish
.global _start
_start:
# first check that we got the correct number of inputs
pop %rax # Get the number of arguments
pop %rdi # Get the program name
pop %rdi # Get the actual argument
# Check if we have the correct number of inputs
cmp $2, %rax
# Jump to Bail if the number is not correct
jne Bail
# Load our preferred mode
mov $0755, %rsi
# Load the syscall number for chmod
mov $90, %rax
# Call the kernel
syscall
Done:
# program completed Successfully
mov $0, %rdi # All is well
mov $60, %rax # put the exit syscall number in eax
syscall # Call it a good day
Bail:
# Second terminate with an error
mov $1, %rdi # there was an error
mov $60, %rax # put the exit syscall number in eax
syscall # bail out