通过内核编译法向Linux内核添加系统调用

1.    cd /usr/src  
2.    wget https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.5.7.tar.xz  

1.    tar -xvf linux-5.5.7.tar.xz  

1.    sudo vim linux-5.5.7/arch/x86/entry/syscalls/syscall_64.tbl  

1.    335     common      mysyscall        __x64_sys_mysyscall

1.    sudo vim linux-5.5.7/include/linux/syscalls.h

1.    asmlinkage long sys_mysyscall(int number);

1.    sudo vim linux-5.5.7/kernel/sys.c

1.    SYSCALL_DEFINE1(mysyscall, int, number) {  
2.        int result = number * number * number;  
3.        printk("The result is %d\n", result);  
4.        return 0;  
5.    }  

1.    cd linux-5.5.7/                            //进入内核文件夹
2.    sudo cp /usr/src/linux-headers-5.3.0-40-generic/.config /usr/src/linux-5.5.7 //复制内核配置
3.    make mrproper                                //删除以前编译产生的垃圾文件  
4.    make clean    
5.    make menuconfig                              //选择Save保存再Exit
6.    make -j4                                     //编译内核  
7.    make modules_install                         //安装模块  
8.    make install                                 //安装内核  

1.    #include <stdio.h>  
2.    #include <sys/ptrace.h>  
3.    #include <sys/types.h>  
4.    #include <sys/wait.h>  
5.    #include <sys/user.h>  
6.    #include <sys/reg.h>  
7.    #include <sys/syscall.h>  
8.    #include <unistd.h>  
9.    #include <linux/kernel.h>  
10.      
11.    int main () {  
12.        syscall(335,4);  
13.        return 0;  
14.    }