HackMD
Add System Call to Arm64 Linux kernel with M2 Chip
Environment
- MBP with M2 chip (2023)
- MacOS 13.3 (22E252)
- Vmware with Ubuntu 64bit 22.04.3 arm-64 architecture
Prepare
Download the Linux Kernel Archives (https://www.kernel.org) or using
wget -P ~/ https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.15.137.tar.xz
Get into root mode
sudo su // or sudo -i
Decompress files to /usr/src
tar -xvf linux-5.15.137.tar.xz -C /usr/src
Update apt
sudo apt update && sudo apt upgrade -y
Install package which can help us to build kernel
sudo apt install build-essential libncurses-dev libssl-dev libelf-dev bison flex -y
Install vim
sudo apt install vim -y
Clear package
sudo apt clean && sudo apt autoremove -y
Add system calls hello
Create directory
cd /usr/src/linux-5.15.137
mkdir hello
cd hello
Create hello.c
vim hello.c
Content of hello.c
#include <linux/kernel.h>
#include <linux/syscalls.h>
SYSCALL_DEFINE0(hello){
printk("Hello world!\n");
return 0;
}
Create Makefile under the same dir
vim Makefile
Content of Makefile
obj-y := hello.o
Back to previous dir and open makefile
# 回上個目錄
cd ..
# 打開此目錄下的 Makefile
vim Makefile
Find core-y and append the hello/ into it
core-y := kernel/ certs/ mm/ fs/ ipc/ security/ crypto/ hello/
Add system call to table and note the system call number
–––––- For ARM64 –––––-
/usr/src/linux-5.15.137/include/uapi/asm-generic/unistd.h
// add your syscall
#define __NR_hello 441
__SYSCALL(__NR_hello, sys_hello)
...
// modify the total number 441 -> 442
#define __NR_syscalls 442
/arch/arm64/include/asm/unistd.h
#define __NR_compat_syscalls number+1
––––––––––––––––––
Add asmlinkage long sys_hello(void); to syscalls.h
# 把目錄轉回去
cd /usr/src/linux-5.15.137
vim include/linux/syscalls.h
#加入一行(這行直接加在檔案的最下面就好)
註: 在vim編輯檔案的時候 可以按shift+G就會跳到最後一行
asmlinkage long sys_hello(void);
Compile Kernel
make localmodconfig
make localmodconfig
#這邊會跳出一大堆問你要不要裝的套件,全部按enter跳過就好
Check processor number
nproc
用幾核心去編譯
make -j12
如果要重新make，請先使用
make clean
make -j12
Install Kernel
sudo make modules_install -j12
sudo make install -j12
Update boot loader and rboot
sudo update-grub
reboot
Check kernel version
uname -r
Issues
If kernel version doesn't update
vim /etc/default/grub
GRUB_TIMEOUT_STYLE: hidden -> menu
GRUB_TIMEOUT: 0 -> -1
update-grub
reboot
Make Failed –> Modify .config
can't read modules.order: No such file or directory
make:*** [Makefile:1544 __modinstpre] Error2
sudo vim .config
CONFIG_SYSTEM_TRUSTED_KEYS = ""
CONFIG_SYSTEM_REVOCATION_KEYS = ""
Make modules failed –> Install dwarves
.tmp_vmlinux.btf: pahole(pahole) is not available
Failed to generate BTF for vmlinux
Try to disable CONFIG_DEBUG_INFO_BTF
make:***[Makefile:1227:vmlinux] Error1
sudo apt-get install dwarves
