[英]Writing x86_64 linux kernel module in assembler
I try write simple kernel module (v3.6) in nasm, but insmod say me:我尝试在 nasm 中编写简单的内核模块 (v3.6),但 insmod 告诉我:
$ sudo insmod ./hello.ko
insmod: ERROR: could not insert module ./hello.ko: Invalid module format
$ echo $?
1
I compile my code with:我编译我的代码:
$ nasm -f elf64 -o hello.m hello.asm
$ ld -m elf_x86_64 -r -o hello.ko hello.m
and my module code:和我的模块代码:
section .modinfo
__mod_kernel_version db "kernel_version=3.6.8", 0
__mod_license db "license=GPL", 0
__mod_author db "author=actics", 0
__mod_description db "description=hello world module in nasm", 0
section .data
init_mess db "init_module", 10, 0
cleanup_mess db "cleanup_module", 10, 0
section .text
global init_module
global cleanup_module
extern printk
init_module:
push rbp
mov rbp, rsp
xor rax, rax
mov rdi, init_mess
call printk
xor rax, rax
mov rsp, rbp
pop rbp
ret
cleanup_module:
push rbp
mov rbp, rsp
xor rax, rax
mov rdi, cleanup_mess
call printk
xor rax, rax
mov rsp, rbp
pop rbp
ret
Please help.请帮忙。 In internets i found 1 link with equal code for 2.4, but he doesnt work too My system - archlinux with 3.6.8 kernel
在互联网上我发现 1 个链接与 2.4 的相同代码,但他也不起作用我的系统 - archlinux 与 3.6.8 内核
UPDATE: in nasm forum i find thread with interesting solution.更新:在 nasm 论坛中,我找到了有趣的解决方案。 It's work for me, if my module do return 0 and exit:) But if i try add "extern printk" the insmod say me next:
它对我有用,如果我的模块确实返回 0 并退出 :) 但是如果我尝试添加“extern printk”,insmod 接下来会告诉我:
ERROR: could not insert module hello.ko: Invalid parameters
What i'm doing wrong?我做错了什么? my code:
我的代码:
[bits 64]
global init_module
global cleanup_module
;extern printk
section .modinfo
__mod_description8 db 'description=Simple module',0
align 16,db 0
__mod_author7 db 'author=That´s me',0
__mod_license6 db 'license=GPL',0
align 16,db 0
__module_depends db 'depends=',0
align 32,db 0
__mod_vermagic5 db 'vermagic=3.6.8-1-ARCH SMP preempt mod_unload modversions ',0 ;from a .ko module of my system
section __versions
____versions db 0xdf, 0xbc, 0xbf, 0x8c, 0, 0, 0, 0, "module_layout" ;from a .ko module of my system
align 64,db 0
section .data
init_mess db "init_module", 10, 0
cleanup_mess db "cleanup_module", 10, 0
section .text
init_module:
xor rax, rax
ret
cleanup_module:
xor rax, rax
ret
section .gnu.linkonce.this_module
times 24 db 0
__name: db 'Simple', 0
times (0x168 - 24 - 7) db 0
__init_module: dq init_module
times 0x2ac db 0
__cleanup_module: dq cleanup_module
times 1152 db 0
this code work with: nasm -f elf64 hello.asm -o hello.o此代码适用于:nasm -f elf64 hello.asm -o hello.o
but if i uncomment printk this no working!)但如果我取消注释 printk 这不起作用!)
What I did was write a small C wrapper using the standard module macros and link it with the main module code that's written in asm.我所做的是使用标准模块宏编写一个小型 C 包装器,并将其与用 asm 编写的主模块代码链接起来。 Use the normal kernel build system to build it.
使用正常的内核构建系统来构建它。
module.c:模块.c:
#include <linux/module.h>
MODULE_AUTHOR("A. U. Thor");
MODULE_DESCRIPTION("Description");
MODULE_LICENSE("GPL");
extern int asm_init(void);
int main_init(void)
{
return asm_init();
}
module_init(main_init);
main.asm:主要汇编程序:
[bits 64]
global asm_init
asm_init:
xor rax, rax
ret
Makefile:生成文件:
obj-m += test.o
test-objs := module.o main.o
$(KBUILD_EXTMOD)/main.o: main.asm
nasm -f elf64 -o $@ $^
obj-m += memory_asm.o
memory_asm-objs := module.o main.o
$(KBUILD_EXTMOD)/main.o: $(src)/main.asm
nasm -f elf64 -o $@ $^ && echo "" > $(src)/.main.o.cmd
Build using command: make -C <path_to_kernel_src> M=$PWD
使用命令构建:
make -C <path_to_kernel_src> M=$PWD
change the Makefile to:将 Makefile 更改为:
obj-m += memory_asm.o
memory_asm-objs := module.o main.o
$(KBUILD_EXTMOD)/main.o: $(src)/main.asm
nasm -f elf64 -o $@ $^ && echo "" > $(src)/.main.o.cmd
k you have to use gcc to compile it k and link it with the kernel directory... k 你必须使用 gcc 来编译它 k 并将它链接到内核目录...
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