需求：在ubuntu机器上面直接调试内核模块，编译出ko文件，直接插入内核。

1、Makefile实现

vi Makefile

obj-m := test.o
CURRENT_PATH := $(shell pwd)
LINUX_KERNEL := $(shell uname -r)
LINUX_KERNEL_PATH := /usr/src/linux-headers-$(LINUX_KERNEL)

all:
    make -C $(LINUX_KERNEL_PATH) M=$(CURRENT_PATH) modules
clean:
    make -C $(LINUX_KERNEL_PATH) M=$(CURRENT_PATH) clean

2、test.c

#include <linux/init.h>
#include <linux/module.h>
#include <linux/gfp.h>

MODULE_LICENSE("GPL");
static int __init __get_free_pages_init(void);
static void __exit __get_free_pages_exit(void);

unsigned long addr = 0;

int __init __get_free_pages_init(void)
{
    addr = __get_free_pages( GFP_KERNEL, 3); //分配８个物理页

    if (!addr)
    {
        return -ENOMEM;
    }
    else
        printk("__get_free_pages Successfully!,\naddr = 0x%lx\n",addr);
}

void __exit __get_free_pages_exit(void)
{
    if (addr)
    {
        free_pages(addr,3);
        printk("free_pages OK!\n");
    }
    printk("exit!\n");
}

module_init(__get_free_pages_init);
module_exit(__get_free_pages_exit);

3、调试

3.1 插入模块

insmod test.ko
demsg -c
[ 2103.082112] free_pages OK!
[ 2103.082114] exit!
[ 2540.899198] __get_free_pages Successfully!,
               addr = 0xffff9a4599d90000
[ 2540.899201] do_init_module: 'test'->init suspiciously returned 57, it should follow 0/-E convention
               do_init_module: loading module anyway...
[ 2540.899204] CPU: 2 PID: 11891 Comm: insmod Tainted: G           OE    4.15.0-30deepin-generic #31
[ 2540.899205] Hardware name: IPASON /H310MHP, BIOS 5.12 07/18/2019
[ 2540.899206] Call Trace:
[ 2540.899211]  dump_stack+0x63/0x8b
[ 2540.899213]  do_init_module+0x8d/0x219
[ 2540.899215]  load_module+0x19bb/0x1dd0
[ 2540.899217]  ? ima_post_read_file+0x83/0xa0
[ 2540.899219]  SYSC_finit_module+0xe5/0x120
[ 2540.899220]  ? SYSC_finit_module+0xe5/0x120
[ 2540.899222]  SyS_finit_module+0xe/0x10
[ 2540.899224]  do_syscall_64+0x73/0x130
[ 2540.899226]  entry_SYSCALL_64_after_hwframe+0x3d/0xa2
[ 2540.899231] RIP: 0033:0x7f52c7e0a229
[ 2540.899232] RSP: 002b:00007ffc4fb34f98 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
[ 2540.899233] RAX: ffffffffffffffda RBX: 0000563012d2a1f0 RCX: 00007f52c7e0a229
[ 2540.899234] RDX: 0000000000000000 RSI: 0000563010b84638 RDI: 0000000000000003
[ 2540.899235] RBP: 0000563010b84638 R08: 0000000000000000 R09: 00007f52c80c1ea0
[ 2540.899236] R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000000
[ 2540.899237] R13: 0000563012d29130 R14: 0000000000000000 R15: 0000000000000000

3.2 卸载模块

[ 2686.817997] free_pages OK!
[ 2686.817999] exit!