創(chuàng)建內(nèi)核字符模塊和oops信息了解

簡(jiǎn)單記錄下Linux Oops的定位步驟。首先創(chuàng)建一個(gè)demo，這個(gè)demo是創(chuàng)建一個(gè)字符設(shè)備demo。

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一、創(chuàng)建demo 模塊的代碼

#include?<linux/init.h>
#include?<linux/module.h>
#include?<linux/cdev.h>
#include?<linux/fs.h>
#include?<linux/device.h>
#define?MINOR_BASE?0
#define?COUNT_NUM?3
static?struct??cdev?*cdevp?=?NULL;
static?dev_t?dev;
struct?class?*demo_class?=?NULL;
struct?device?*drv_device;
int?demo_open(struct?inode?*node,?struct?file?*filp)
{
????printk(KERN_INFO?"%s?%d?demo_open?called...\n",__func__,__LINE__);
int?*p?=?NULL;
*p?=?1;??/*?空指針賦值?*/
????return?0;
}
int?demo_release(struct?inode?*node,?struct?file?*filp)
{
????printk(KERN_INFO?"%s?%d?demo_release?called...\n",__func__,__LINE__);
????return?0;
}
ssize_t?demo_read(struct?file?*filep,?char?__user?*user,?size_t?size,?loff_t?*loffp)
{
????printk(KERN_INFO?"%s?%d?demo_read?called...\n",__func__,__LINE__);
????return?0;
}
ssize_t?demo_write(struct?file?*?filep,?const?char?__user?*user,?size_t?size,?loff_t?*?loffp)
{
????printk(KERN_INFO?"%s?%d?demo_write?called...\n",__func__,__LINE__);
????return?size;
}
struct?file_operations?opfp?=?{
????.owner?=?THIS_MODULE,
????.open?=?demo_open,
????.release?=?demo_release,
????.read?=?demo_read,
????.write?=?demo_write,
????};
static?int?__init?demo_init(void)
{
????int?ret;
????//dev_t
????ret?=?alloc_chrdev_region(&dev,MINOR_BASE,COUNT_NUM,"cdev_demo");
????if(?ret<0?){
????pr_err("%s?%d?alloc_chrdev_region?error...\n",__func__,__LINE__);
????goto?err_ret;
????}
????pr_info("MARJO?DEV_T?=?%d\n",MAJOR(dev));
????//cdev
????cdevp?=?cdev_alloc();
????if(?NULL?==?cdevp?){
????pr_err("%s?%d?cdev_alloc?error...\n",__func__,__LINE__);
????goto?err_chrdev_unreg;
????}
????//init?cdev
????cdev_init(cdevp,?&opfp);
????//add?dev
????ret?=?cdev_add(cdevp,?dev,?COUNT_NUM);
????if(?ret<0?){
????pr_err("cdev_add?error...\n");
????goto?err_chrdev_unreg;
????}
//create?class
demo_class?=?class_create(THIS_MODULE,?"demo");
if?(IS_ERR(demo_class))?{
pr_err("%s?%d?demo:?class_create?failed?for?adf_ctl\n",__func__,__LINE__);
goto?err_cdev_del;
}
//create?dev?file
????drv_device?=?device_create(demo_class,?NULL,?dev,?NULL,?"demo");
if?(IS_ERR(drv_device))?{
pr_err("demo:?failed?to?create?device\n");
goto?err_class_destr;
}
????pr_info("device?created?success\n");
????printk("++++++++++++++%s?%s?%d+++++++++++++++\n",__FILE__,__func__,__LINE__);
return?0;
err_class_destr:
class_destroy(demo_class);
err_cdev_del:
cdev_del(cdevp);
????err_chrdev_unreg:
????unregister_chrdev_region(dev,COUNT_NUM);???
????err_ret:
????return?ret;?
}
static?void?__exit?demo_exit(void)
{
device_destroy(demo_class,dev);
????cdev_del(cdevp);
class_destroy(demo_class);
????unregister_chrdev_region(dev,COUNT_NUM);???
printk("+++++++++++++%s?%s?%d+++++++++++++++\n",__FILE__,__func__,__LINE__);
}
module_init(demo_init);
module_exit(demo_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("zxh@2019/1/17");
MODULE_DESCRIPTION("fist?test?demo");

二、編譯demo的makefile //模塊的統(tǒng)一格式

obj-m:=demo.o
KDIR:=/usr/src/linux-headers-3.16.0-30-generic??#kernel源碼路徑
PWD:=$(shell?pwd)
all:??#偽指令，所有目標(biāo)的目標(biāo)，make默認(rèn)會(huì)匹配all
$(MAKE)?-C?$(KDIR)?SUBDIRS=$(PWD)?modules
????
@rm?-rf?*.mod.*???#@?執(zhí)行命令不顯示
@rm?-rf?*.o
@rm?-rf?Module.*
@rm?-rf?modules.*
.PHANY:clean
clean:
rm?-rf?*.ko?*.o

三、insmod demo.ko

通過dmesg查看打印信息

[? 527.256991] MARJO DEV_T = 250

[? 527.265068] device created success

[? 527.265081] ++++++++++++++/home/luster/share/BiTree/module_demo/demo.c demo_init 82+++++++++++++++

四、cat /dev/demo

通過dmesg查看打印信息

[?6319.390421]?demo_open?15?demo_open?called...//?demo_open函數(shù)被調(diào)用
[?6319.391910]?BUG:?unable?to?handle?kernel?NULL?pointer?dereference?at???(null)
[?6319.392210]?IP:?[<f99d5029>]?demo_open+0x29/0x40?[demo]
[?6319.392685]?*pdpt?=?0000000034814001?*pde?=?0000000000000000?
[?6319.392747]?Oops:?0002?[#1]?SMP?
[?6319.392842]?Modules?linked?in:?demo(OE)?xt_nat?xt_REDIRECT?xt_tcpudp?iptable_nat?nf_conntrack_ipv4?nf_defrag_ipv4?nf_nat_ipv4?nf_nat?nf_conntrack?ip_tables?x_tables?esn_cfs(OE)?snd_ens1371?snd_ac97_codec?ac97_bus?gameport?snd_pcm?coretemp?crc32_pclmul?snd_seq_midi?snd_seq_midi_event?snd_rawmidi?aesni_intel?aes_i586?xts?lrw?bnep?rfcomm?snd_seq?bluetooth?gf128mul?6lowpan_iphc?vmw_balloon?ablk_helper?cryptd?vmwgfx?snd_seq_device?serio_raw?snd_timer?joydev?ttm?drm_kms_helper?snd?soundcore?binfmt_misc?vmw_vmci?shpchp?drm?i2c_piix4?parport_pc?ppdev?lp?parport?mac_hid?hid_generic?usbhid?hid?psmouse?mptspi?mptscsih?mptbase?pcnet32?mii?scsi_transport_spi?pata_acpi?floppy
[?6319.393110]?CPU:?0?PID:?3304?Comm:?cat?Tainted:?G???????????OE?3.16.0-30-generic?#40~14.04.1-Ubuntu
[?6319.393120]?Hardware?name:?VMware,?Inc.?VMware?Virtual?Platform/440BX?Desktop?Reference?Platform,?BIOS?6.00?07/02/2015
[?6319.393162]?task:?e04da520?ti:?e4bec000?task.ti:?e4bec000
[?6319.393223]?EIP:?0060:[<f99d5029>]?EFLAGS:?00010246?CPU:?0
[?6319.393246]?EIP?is?at?demo_open+0x29/0x40?[demo]
[?6319.393261]?EAX:?00000000?EBX:?dd92efc0?ECX:?f6f6bb88?EDX:?f6f6a5c4
[?6319.393269]?ESI:?d50dbca4?EDI:?e074f3c0?EBP:?e4beddbc?ESP:?e4beddb0
[?6319.393279]??DS:?007b?ES:?007b?FS:?00d8?GS:?00e0?SS:?0068
[?6319.393298]?CR0:?8005003b?CR2:?00000000?CR3:?3486a000?CR4:?001407f0
[?6319.393365]?Stack:
[?6319.393404]??f99d6024?f99d623c?0000000f?e4beddd8?c11920d7?f99d7000?00000000?e074f3c0
[?6319.393445]??d50dbca4?00000000?e4beddfc?c118c34c?00002000?c1192050?e074f3c8?e054b880
[?6319.393448]??00000000?e3c0a000?e074f3c0?e4bede10?c118c4bc?e4bedecc?00000000?00000000
[?6319.393470]?Call?Trace:?//函數(shù)調(diào)用關(guān)系
[?6319.393767]??[<c11920d7>]?chrdev_open+0x87/0x190
[?6319.393780]??[<c118c34c>]?do_dentry_open+0x1ec/0x2e0
[?6319.393798]??[<c1192050>]???cdev_put+0x20/0x20
[?6319.393803]??[<c118c4bc>]?vfs_open+0x3c/0x50
[?6319.393806]??[<c1198cf1>]?do_last+0x4c1/0xf10
[?6319.393807]??[<c1199c6f>]???link_path_walk+0x5f/0x6d0
[?6319.393829]??[<c12bf16a>]???apparmor_file_alloc_security+0x4a/0x140
[?6319.393831]??[<c119ac70>]?path_openat+0xb0/0x540
[?6319.393833]??[<c119c9d1>]?do_filp_open+0x31/0x80
[?6319.393836]??[<c118d745>]?do_sys_open+0x115/0x260
[?6319.393866]??[<f9adeb1f>]???file_redirect_check+0xaf/0x3a0?[esn_cfs]
[?6319.393871]??[<f9ad0000>]???GetNextDict+0x60/0xb0?[esn_cfs]
[?6319.393881]??[<c118d8b2>]?SyS_open+0x22/0x30
[?6319.393885]??[<f9adef56>]?efs_sys_open+0x66/0x110?[esn_cfs]
[?6319.393910]??[<c169285f>]?sysenter_do_call+0x12/0x12
[?6319.393929]?Code:?<c7>?05?00?00?00?00?01?00?00?00?c9?c3?8d?74?26?00?8d?bc?27?00?00?00
[?6319.394128]?EIP:?[<f99d5029>]?demo_open+0x29/0x40?[demo]?SS:ESP?0068:e4beddb0
[?6319.394152]?CR2:?0000000000000000
[?6319.394381]?---[?end?trace?fc2838f795f2c84d?]---

五、分析oops

1）cat /dev/demo會(huì)調(diào)用模塊的demo_open函數(shù)

[ 6319.390421] demo_open 15 demo_open called...

2）然后就產(chǎn)生了異常

[ 6319.391910] BUG: unable to handle kernel NULL pointer dereference at? ?(null)

通過BUG可以看出是使用空指針引起的異常，這和我們寫的代碼一直。

[ 6319.392210] IP: [<f99d5029>] demo_open+0x29/0x40 [demo]

程序的pc指針指向了demo_open 加0x29/0x40的位置

[ 6319.392747] Oops: 0002 [#1] SMP?

oops的錯(cuò)誤碼，#1表示發(fā)生一次

3）通過objdump命令，查看代碼的反匯編

objdump?-S?demo.ko?//-S顯示源代碼的反匯編，比較清晰
demo.ko:?????file?format?elf32-i386
Disassembly?of?section?.text:
00000000?<demo_open>:
???0:55???????????????????push???%ebp
??31:89?e5????????????????add????%al,(%eax)
??33:83???????????????????leave??
??34:ec???????????????????ret????
??35:0c?e8?fc?ff??????????lea????0x0(%esi,%eiz,1),%esi
??39:ff?ff?c7?44?24?08?0f?lea????0x0(%edi,%eiz,1),%edi
??40:00???????????????????push???%ebp
??41:00?00????????????????mov????%esp,%ebp
??43:c7?44?24?????????????sub????$0xc,%esp
??46:04?36?00?00?00???????call???47?<demo_open+0x17>
??4b:c7?04?24?00?00?00?00?movl???$0x16,0x8(%esp)
??52:e8?
??53:fc?ff?ff?ff?31?c0?c7?movl???$0x29,0x4(%esp)
??5a:05?
??5b:00?00?00?00?01?00?00?movl???$0x0,(%esp)
??62:00?c9?c3?8d?74???????call???63?<demo_open+0x33>
??67:26?00????????????????xor????%eax,%eax
??69:8d???????????????????leave??
??6a:bc???????????????????ret????
??6b:27???????????????????nop
??6c:00?00?00?00??????????lea????0x0(%esi,%eiz,1),%esi
00000070?<demo_release>:
??70:55???????????????????push???%ebp
??71:89?e5????????????????mov????%esp,%ebp
??73:83?ec?0c?????????????sub????$0xc,%esp
??76:e8?fc?ff?ff?ff???????call???77?<demo_open+0x47>
??7b:c7?44?24?08?16?00?00?movl???$0x1c,0x8(%esp)
??82:00?
??83:c7?44?24?04?29?00?00?movl???$0x1f,0x4(%esp)
??8a:00?
??8b:c7?04?24?00?00?00?00?movl???$0x1d,(%esp)
??92:e8?fc?ff?ff?ff???????call???93?<demo_open+0x63>
??97:31?c0????????????????xor????%eax,%eax
??99:c9???????????????????leave??
??9a:c3???????????????????ret????
??9b:90???????????????????nop
??9c:8d?74?26?00??????????lea????0x0(%esi,%eiz,1),%esi
000000a0?<demo_read>:
??a0:55???????????????????push???%ebp
??a1:89?e5????????????????mov????%esp,%ebp
??a3:83???????????????????push???%ebx
??a4:ec?0c?e8?????????????sub????$0xc,%esp
??a7:fc?ff?ff?ff?c7???????call???a8?<demo_open+0x78>
??ac:44?24?08?1c?00?00?00?movl???$0x21,0x8(%esp)
??b3:c7?
??b4:44?24????????????????mov????%ecx,%ebx
??b6:04?1f?00?00?00?c7?04?movl???$0x14,0x4(%esp)
??bd:24?
??be:1d?00?00?00?e8?fc?ff?movl???$0x3a,(%esp)
??c5:ff?ff?31?c0?c9???????call???c6?<demo_open+0x96>
??ca:c3?90?8d?????????????add????$0xc,%esp
??cd:74?26????????????????mov????%ebx,%eax
...
000000d0?<demo_write>:
??d0:55???????????????????pop????%ebp
??d1:89???????????????????ret????
??d2:Address?0x00000000000000d2?is?out?of?bounds.
Disassembly?of?section?.init.text:
00000132?<init_module>:
?132:55???????????????????push???%ebp
?133:31?d2????????????????xor????%edx,%edx
?135:89?e5????????????????mov????%esp,%ebp
?137:b9?03?00?00?00???????mov????$0x3,%ecx
?13c:53???????????????????push???%ebx
?13d:b8?08?00?00?00???????mov????$0x8,%eax
?142:83?ec?14?????????????sub????$0x14,%esp
?145:c7?04?24?58?00?00?00?movl???$0x58,(%esp)
?14c:e8?fc?ff?ff?ff???????call???14d?<init_module+0x1b>
?151:85?c0????????????????test???%eax,%eax
?153:89?c3????????????????mov????%eax,%ebx
?155:79?23????????????????jns????17a?<init_module+0x48>
?157:c7?44?24?08?33?00?00?movl???$0x33,0x8(%esp)
?15e:00?
?15f:c7?44?24?04?0a?00?00?movl???$0xa,0x4(%esp)
?166:00?
?167:c7?04?24?20?00?00?00?movl???$0x20,(%esp)
?16e:e8?fc?ff?ff?ff???????call???16f?<init_module+0x3d>
?173:89?d8????????????????mov????%ebx,%eax
?175:e9?5b?01?00?00???????jmp????2d5?<init_module+0x1a3>
?17a:a1?08?00?00?00???????mov????0x8,%eax
?17f:c7?04?24?62?00?00?00?movl???$0x62,(%esp)
?186:c1?e8?14?????????????shr????$0x14,%eax
?189:89?44?24?04??????????mov????%eax,0x4(%esp)
?18d:e8?fc?ff?ff?ff???????call???18e?<init_module+0x5c>
?192:e8?fc?ff?ff?ff???????call???193?<init_module+0x61>
?197:85?c0????????????????test???%eax,%eax
?199:a3?0c?00?00?00???????mov????%eax,0xc
?19e:75?21????????????????jne????1c1?<init_module+0x8f>
?1a0:c7?44?24?08?3a?00?00?movl???$0x3a,0x8(%esp)
?1a7:00?
?1a8:c7?44?24?04?0a?00?00?movl???$0xa,0x4(%esp)
?1af:00?
?1b0:c7?04?24?76?00?00?00?movl???$0x76,(%esp)
?1b7:e8?fc?ff?ff?ff???????call???1b8?<init_module+0x86>
?1bc:e9?03?01?00?00???????jmp????2c4?<init_module+0x192>
?1c1:ba?00?00?00?00???????mov????$0x0,%edx
?1c6:e8?fc?ff?ff?ff???????call???1c7?<init_module+0x95>
?1cb:8b?15?08?00?00?00????mov????0x8,%edx
?1d1:b9?03?00?00?00???????mov????$0x3,%ecx
?1d6:a1?0c?00?00?00???????mov????0xc,%eax
?1db:e8?fc?ff?ff?ff???????call???1dc?<init_module+0xaa>
?1e0:85?c0????????????????test???%eax,%eax
?1e2:89?c3????????????????mov????%eax,%ebx
?1e4:79?11????????????????jns????1f7?<init_module+0xc5>
?1e6:c7?04?24?93?00?00?00?movl???$0x93,(%esp)
?1ed:e8?fc?ff?ff?ff???????call???1ee?<init_module+0xbc>
?1f2:e9?cd?00?00?00???????jmp????2c4?<init_module+0x192>
?1f7:b9?08?00?00?00???????mov????$0x8,%ecx
?1fc:ba?a8?00?00?00???????mov????$0xa8,%edx
?201:b8?00?00?00?00???????mov????$0x0,%eax
?206:e8?fc?ff?ff?ff???????call???207?<init_module+0xd5>
?20b:3d?00?f0?ff?ff???????cmp????$0xfffff000,%eax
?210:a3?00?00?00?00???????mov????%eax,0x0
?215:76?21????????????????jbe????238?<init_module+0x106>
?217:c7?44?24?08?48?00?00?movl???$0x48,0x8(%esp)
?21e:00?
?21f:c7?44?24?04?0a?00?00?movl???$0xa,0x4(%esp)
?226:00?
?227:c7?04?24?48?00?00?00?movl???$0x48,(%esp)
?22e:e8?fc?ff?ff?ff???????call???22f?<init_module+0xfd>
?233:e9?82?00?00?00???????jmp????2ba?<init_module+0x188>
?238:8b?15?08?00?00?00????mov????0x8,%edx
?23e:c7?44?24?10?a8?00?00?movl???$0xa8,0x10(%esp)
?245:00?
?246:c7?44?24?0c?00?00?00?movl???$0x0,0xc(%esp)
?24d:00?
?24e:c7?44?24?04?00?00?00?movl???$0x0,0x4(%esp)
?255:00?
?256:89?54?24?08??????????mov????%edx,0x8(%esp)
?25a:89?04?24?????????????mov????%eax,(%esp)
?25d:e8?fc?ff?ff?ff???????call???25e?<init_module+0x12c>
?262:3d?00?f0?ff?ff???????cmp????$0xfffff000,%eax
?267:a3?00?00?00?00???????mov????%eax,0x0
?26c:76?18????????????????jbe????286?<init_module+0x154>
?26e:c7?04?24?78?00?00?00?movl???$0x78,(%esp)
?275:e8?fc?ff?ff?ff???????call???276?<init_module+0x144>
?27a:a1?00?00?00?00???????mov????0x0,%eax
?27f:e8?fc?ff?ff?ff???????call???280?<init_module+0x14e>
?284:eb?34????????????????jmp????2ba?<init_module+0x188>
?286:c7?04?24?ad?00?00?00?movl???$0xad,(%esp)
?28d:e8?fc?ff?ff?ff???????call???28e?<init_module+0x15c>
?292:c7?44?24?0c?52?00?00?movl???$0x52,0xc(%esp)
?299:00?
?29a:c7?44?24?08?0a?00?00?movl???$0xa,0x8(%esp)
?2a1:00?
?2a2:c7?44?24?04?9c?00?00?movl???$0x9c,0x4(%esp)
?2a9:00?
?2aa:c7?04?24?cc?00?00?00?movl???$0xcc,(%esp)
?2b1:e8?fc?ff?ff?ff???????call???2b2?<init_module+0x180>
?2b6:31?c0????????????????xor????%eax,%eax
?2b8:eb?1b????????????????jmp????2d5?<init_module+0x1a3>
?2ba:a1?0c?00?00?00???????mov????0xc,%eax
?2bf:e8?fc?ff?ff?ff???????call???2c0?<init_module+0x18e>
?2c4:a1?08?00?00?00???????mov????0x8,%eax
?2c9:ba?03?00?00?00???????mov????$0x3,%edx
?2ce:e8?fc?ff?ff?ff???????call???2cf?<init_module+0x19d>
?2d3:89?d8????????????????mov????%ebx,%eax
?2d5:83?c4?14?????????????add????$0x14,%esp
?2d8:5b???????????????????pop????%ebx
?2d9:5d???????????????????pop????%ebp
?2da:c3???????????????????ret????
Disassembly?of?section?.exit.text:
0000040d?<cleanup_module>:
?40d:55???????????????????push???%ebp
?40e:89?e5????????????????mov????%esp,%ebp
?410:83?ec?10?????????????sub????$0x10,%esp
?413:8b?15?08?00?00?00????mov????0x8,%edx
?419:a1?00?00?00?00???????mov????0x0,%eax
?41e:e8?fc?ff?ff?ff???????call???41f?<cleanup_module+0x12>
?423:a1?0c?00?00?00???????mov????0xc,%eax
?428:e8?fc?ff?ff?ff???????call???429?<cleanup_module+0x1c>
?42d:a1?00?00?00?00???????mov????0x0,%eax
?432:e8?fc?ff?ff?ff???????call???433?<cleanup_module+0x26>
?437:a1?08?00?00?00???????mov????0x8,%eax
?43c:ba?03?00?00?00???????mov????$0x3,%edx
?441:e8?fc?ff?ff?ff???????call???442?<cleanup_module+0x35>
?446:c7?44?24?0c?63?00?00?movl???$0x63,0xc(%esp)
?44d:00?
?44e:c7?44?24?08?00?00?00?movl???$0x0,0x8(%esp)
?455:00?
?456:c7?44?24?04?9c?00?00?movl???$0x9c,0x4(%esp)
?45d:00?
?45e:c7?04?24?f4?00?00?00?movl???$0xf4,(%esp)
?465:e8?fc?ff?ff?ff???????call???466?<cleanup_module+0x59>
?46a:c9???????????????????leave??
?46b:c3???????????????????ret????
?4）分析反匯編
?00000000?<demo_open>:
???0:55???????????????????push???%ebp
??31:89?e5????????????????add????%al,(%eax)
??33:83???????????????????leave??
??34:ec???????????????????ret????
??35:0c?e8?fc?ff??????????lea????0x0(%esi,%eiz,1),%esi
??39:ff?ff?c7?44?24?08?0f?lea????0x0(%edi,%eiz,1),%edi
??40:00???????????????????push???%ebp
??41:00?00????????????????mov????%esp,%ebp
??43:c7?44?24?????????????sub????$0xc,%esp
??46:04?36?00?00?00???????call???47?<demo_open+0x17>
??4b:c7?04?24?00?00?00?00?movl???$0x16,0x8(%esp)
??52:e8?
??53:fc?ff?ff?ff?31?c0?c7?movl???$0x29,0x4(%esp)
??5a:05?
??5b:00?00?00?00?01?00?00?movl???$0x0,(%esp)
??62:00?c9?c3?8d?74???????call???63?<demo_open+0x33>
??67:26?00????????????????xor????%eax,%eax
??69:8d???????????????????leave??
??6a:bc???????????????????ret????
??6b:27???????????????????nop
??6c:00?00?00?00??????????lea????0x0(%esi,%eiz,1),%esi

?因?yàn)殄e(cuò)誤發(fā)生在

demo_open+0x29/0x40

即就是在這一段中間

??46:04?36?00?00?00???????call???47?<demo_open+0x17>
??4b:c7?04?24?00?00?00?00?movl???$0x16,0x8(%esp)
??52:e8?
??53:fc?ff?ff?ff?31?c0?c7?movl???$0x29,0x4(%esp)
??5a:05?
??5b:00?00?00?00?01?00?00?movl???$0x0,(%esp)
??62:00?c9?c3?8d?74???????call???63?<demo_open+0x33>

?5b: 00 00 00 00 01 00 00 movl? ?$0x0,(%esp)：將esp賦值給0x0，即就是空指針賦值。

?

大概流程就是如此，只是了解個(gè)皮毛。

最后，當(dāng)發(fā)生錯(cuò)誤時(shí)，rmmod demo將發(fā)生錯(cuò)誤：Module demo is in use

通過查詢模塊lsmod

module? size? used

demo? 12831? 1

說明模塊被使用，因?yàn)閏at后發(fā)生異常，沒有關(guān)閉demo。

通過查詢資料，大概有兩種方法：1、通過rmmod -f 2、通過編寫另一個(gè)模塊去將模塊的use值改為0，然后再rmmod

第一種：rmmod -f 我的系統(tǒng)不支持

第二種：通過http://www.cppblog.com/csjiaxin/archive/2012/06/06/136382.html?opt=admin方法貌似也不行。

因?yàn)楂@取不到模塊的首地址。

cat?/proc/kallsyms?|?grep?modules
00000000?t?modules_open
00000000?T?set_all_modules_text_rw
00000000?T?set_all_modules_text_ro
00000000?T?print_modules
00000000?r?proc_modules_operations
00000000?r?modules_op
00000000?r?sih_modules_twl5031
00000000?r?sih_modules_twl4030
00000000?d?smp_alt_modules
00000000?d?randomize_modules
00000000?D?kdb_modules
00000000?d?modules
00000000?T?load_default_modules
00000000?t?proc_modules_init
00000000?t?__initcall_proc_modules_init6
00000000?B?modules_disabled
00000000?B?kcore_modules
00000000?b?nr_sih_modules
00000000?b?sih_modules

所以當(dāng)發(fā)生錯(cuò)誤時(shí)，我只能重啟虛擬機(jī)。

文章標(biāo)題：創(chuàng)建內(nèi)核字符模塊和oops信息了解
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