Linux操作系统内核模块与用户程序对比-红联Linux系统门户

　　内核模块是如何开始和结束的

　　用户程序通常从函数main()开始，执行一系列的指令并且当指令执行完成后结束程序。内核模块有一点不同。内核模块要么从函数init_module 或是你用宏module_init指定的函数调用开始。这就是内核模块的入口函数。它告诉内核模块提供那些功能扩展并且让内核准备好在需要时调用它。当它完成这些后，该函数就执行结束了。模块在被内核调用前也什么都不做。

　　所有的模块或是调用cleanup_module或是你用宏 module_exit指定的函数。这是模块的退出函数。它撤消入口函数所做的一切。例如注销入口函数所注册的功能。

　　所有的模块都必须有入口函数和退出函数。既然我们有不只一种方法去定义这两个函数，我将努力使用“入口函数”和“退出函数”来描述它们。但是当我只用init_module 和cleanup_module时，我希望你明白我指的是什么。

　　模块可调用的函数

　　程序员并不总是自己写所有用到的函数。一个常见的基本的例子就是 printf()你使用这些C标准库，libc提供的库函数。这些函数(像printf()) 实际上在连接之前并不进入你的程序。在连接时这些函数调用才会指向你调用的库，从而使你的代码最终可以执行。

　　内核模块有所不同。在hello world模块中你也许已经注意到了我们使用的函数 printk() 却没有包含标准I/O库。这是因为模块是在insmod加载时才连接的目标文件。那些要用到的函数的符号链接是内核自己提供的。也就是说，你可以在内核模块中使用的函数只能来自内核本身。如果你对内核提供了哪些函数符号链接感兴趣，看一看文件/proc/kallsyms。

　　需要注意的一点是库函数和系统调用的区别。库函数是高层的，完全运行在用户空间，为程序员提供调用真正的在幕后完成实际事务的系统调用的更方便的接口。系统调用在内核态运行并且由内核自己提供。标准C库函数printf()可以被看做是一个通用的输出语句，但它实际做的是将数据转化为符合格式的字符串并且调用系统调用 write()输出这些字符串。

　　是否想看一看printf()究竟使用了哪些系统调用? 这很容易，编译下面的代码。

锟斤拷锟斤拷:
#include
int main(void)
{ printf("hello"); return 0; }

　
　　使用命令gcc -Wall -o hello hello.c编译。用命令 strace hello行该可执行文件。是否很惊讶？每一行都和一个系统调用相对应。 strace[3] 是一个非常有用的程序，它可以告诉你程序使用了哪些系统调用和这些系统调用的参数，返回值。这是一个极有价值的查看程序在干什么的工具。在输出的末尾，你应该看到这样类似的一行 write(1, "hello", 5hello)。这就是我们要找的。藏在面具printf() 的真实面目。既然绝大多数人使用库函数来对文件I/O进行操作(像 fopen, fputs, fclose)。你可以查看man说明的第二部分使用命令man 2 write. 。man说明的第二部分专门介绍系统调用(像kill()和read())。 man说明的第三部分则专门介绍你可能更熟悉的库函数， (像cosh()和random())。

　　你甚至可以编写代码去覆盖系统调用，正如我们不久要做的。骇客常这样做来为系统安装后门或木马。但你可以用它来完成一些更有益的事，像让内核在每次某人删除文件时输出 “ Tee hee, that tickles!” 的信息。

0.0.0.* 于 2007-07-06 00:31:18发表:

bonus meilleur casino en ligne http://www.freewebs.com/casino-729/casino-2.html free casino game free casino games http://www.freewebs.com/casino-60/casino-7.html roulette table free roulette game http://www.freewebs.com/casino-60/roulette-1.html http://www.freewebs.com/casino-60/slots-4.html free slots online slots las vegas casino http://www.freewebs.com/casino-60/casino-1.html free online casino

72.131.32.* 于 2007-07-06 00:23:37发表:

craps table http://www.freewebs.com/casino-49/craps-2.html free online craps http://www.freewebs.com/casino-49/keno-4.html keno casino keno casino play keno online free online keno http://www.freewebs.com/casino-49/keno-6.html free casino game http://www.freewebs.com/casino-78/casino-6.html las vegas casino http://www.freewebs.com/casino-41/card-stud-2.html seven card stud 7 card stud

202.181.246.* 于 2007-07-06 00:19:56发表:

free online slots slots online http://www.freewebs.com/casino-49/slots-6.html instant payday loan http://www.bernhardnordh.nu/_disk6/0000189f.htm instant payday loan free baccarat baccarat online http://www.freewebs.com/casino-49/baccarat-5.html http://www.freewebs.com/casino-41/roulette-3.html roulette tip casino roulette free casino slots http://www.freewebs.com/casino-49/slots-5.html online slots

72.232.63.* 于 2007-07-05 18:15:51发表:

72.232.63.* 于 2007-07-05 18:15:20发表:

72.232.63.* 于 2007-07-05 18:14:18发表:

72.232.63.* 于 2007-07-05 18:13:51发表:

72.232.63.* 于 2007-07-05 18:13:40发表:

12.217.221.* 于 2007-07-05 17:45:04发表:

http://www.freewebs.com/casino-703/casino-3.html meilleur casino en ligne casino gratuit http://www.freewebs.com/casino-60/blackjack-4.html blackjack online play free blackjack http://www.freewebs.com/casino-60/craps-1.html casino craps how to play craps blackjack game online blackjack http://www.freewebs.com/casino-60/blackjack-7.html casinos casino de paris http://www.freewebs.com/casino-703/casino-2.html

69.68.207.* 于 2007-07-05 17:37:52发表:

roulette table online roulette http://www.freewebs.com/casino-60/roulette-5.html http://www.freewebs.com/casino-466/casino-2.html jouez au casino top promotions en ligne keno online play keno online http://www.freewebs.com/casino-60/keno-1.html play craps online free play craps http://www.freewebs.com/casino-49/craps-7.html http://www.freewebs.com/casino-274/casino-1.html casino france casino france

74.135.247.* 于 2007-07-05 17:37:42发表:

play craps online free http://www.freewebs.com/casino-60/craps-7.html casino craps roulette tip online roulette poker http://www.freewebs.com/casino-60/roulette-3.html top casino en ligne bonus de casino en ligne http://www.freewebs.com/casino-919/casino-3.html jouez au casino http://www.freewebs.com/casino-758/casino-2.html jouez au casino free keno games http://www.freewebs.com/casino-60/keno-6.html play keno online

0.0.0.* 于 2007-07-05 17:19:11发表:

http://www.freewebs.com/casino-49/keno-1.html keno online free keno free online casino free casino http://www.freewebs.com/casino-49/casino-2.html http://www.freewebs.com/casino-78/casino-5.html casino gambling casino gambling no faxing payday loan no faxing payday loan http://destinychristianministries.org/_disc7/000004c3.htm http://www.phimuepsilon.com/forum/_disc2/000039f1.htm cash advance payday loan cash advance payday loan

0.0.0.* 于 2007-07-05 17:15:53发表:

casino fran?is online casino http://www.freewebs.com/casino-781/casino-2.html bonus de casino en ligne gambling http://www.freewebs.com/casino-821/casino-1.html 7 card stud 7 card stud http://www.freewebs.com/casino-60/card-stud-4.html baccarat online play baccarat http://www.freewebs.com/casino-60/baccarat-5.html blogspot.com fax loan no payday site blogspot.com fax loan no payday site http://www.ayocreations.com/Forum/0000335c.htm

81.252.205.* 于 2007-07-05 17:05:31发表:

bonus gratuits http://www.freewebs.com/casino-863/casino-3.html jouez au casino keno casino keno casino http://www.freewebs.com/casino-60/keno-3.html military payday loan http://www.bernhardnordh.nu/_disk6/000018a0.htm military payday loan http://www.freewebs.com/casino-60/card-stud-6.html seven card stud 7 card stud http://www.freewebs.com/casino-60/blackjack-6.html free blackjack game online blackjack game

0.0.0.* 于 2007-07-05 16:59:38发表:

payday loan 1000 payday loan 1000 http://cahn.mnsu.edu/fall2001laugh/_disc3/000003ad.htm military payday loan http://www.bernhardnordh.nu/_disk6/000018a0.htm military payday loan quik payday loan quik payday loan http://www.ipaquebec.ca/_disc/00000b44.htm casino baccarat free baccarat http://www.freewebs.com/casino-49/baccarat-6.html http://www.freewebs.com/casino-41/slots-5.html free online slots progressive slots

67.183.66.* 于 2007-07-05 16:58:59发表:

cash until payday loan cash until payday loan http://www.technologyamerica.net/_discuss1/0000138e.htm payday loan store payday loan store http://www.trinityvikings.org/messageboards/_michellegasser/00000046.htm http://destinychristianministries.org/_disc7/000004c5.htm ez payday loan ez payday loan http://www.smsannafrank.it/_disc1/00000033.htm no fax payday loan no fax payday loan http://www.bigtalldirect.com/pages/_disc2/00004935.htm payday loan canada payday loan canada

69.118.247.* 于 2007-07-05 16:50:17发表:

seven card stud 7 card stud http://www.freewebs.com/casino-41/card-stud-6.html online baccarat baccarat game http://www.freewebs.com/casino-41/baccarat-3.html http://www.sftyeeclub.com/fishTalk/_fishTalesDisc/0000003e.htm sonic payday loan sonic payday loan http://www.freewebs.com/casino-49/card-stud-7.html seven card stud 7 card stud http://www.freewebs.com/casino-31/card-stud-5.html seven card stud 7 card stud

212.115.229.* 于 2007-07-05 16:46:13发表:

bonus http://www.freewebs.com/casino-729/casino-1.html top promotions en ligne

67.190.129.* 于 2007-07-05 15:49:18发表:

online casino roulette roulette table http://www.freewebs.com/casino-60/roulette-2.html http://www.freewebs.com/casino-279/casino-1.html top promotions en ligne bonus gratuits http://www.freewebs.com/casino-60/roulette-6.html roulette online play roulette meilleur casino en ligne meilleur casino en ligne http://www.freewebs.com/casino-170/casino-1.html play baccarat baccarat online http://www.freewebs.com/casino-60/baccarat-2.html

81.252.205.* 于 2007-07-05 15:45:28发表:

7 card stud http://www.freewebs.com/casino-41/card-stud-4.html seven card stud sonic payday loan sonic payday loan http://www.msd.k12.or.us/schools/mhs/AlumDiscuss/000012ec.htm payday advance loan payday advance loan http://www.sftyeeclub.com/fishTalk/_fishTalesDisc/0000003f.htm cash advance paydayloans cash advance paydayloans http://www.bigtalldirect.com/pages/_disc2/00004937.htm internet roulette roulette gambling http://www.freewebs.com/casino-49/roulette-6.html

218.129.204.* 于 2007-07-05 15:40:43发表:

no fax payday loan http://www.pelicanpointe.net/_disc1/00001c88.htm no fax payday loan free casino games free casino games http://www.freewebs.com/casino-41/casino-1.html free baccarat free baccarat http://www.freewebs.com/casino-53/baccarat-6.html free roulette online roulette poker http://www.freewebs.com/casino-49/roulette-2.html casino gambling free casino game http://www.freewebs.com/casino-78/casino-7.html

217.9.231.* 于 2007-07-05 15:34:42发表:

free slots machine game free slots machine game http://www.freewebs.com/casino-49/slots-1.html roulette online internet roulette http://www.freewebs.com/casino-53/roulette-1.html savings account payday loan savings account payday loan http://www.trinityvikings.org/messageboards/_michellegasser/00000048.htm payday loan personal http://www.ryangoodson.com/disc1/00000d6d.htm payday loan personal play baccarat http://www.freewebs.com/casino-41/baccarat-2.html online baccarat

71.207.48.* 于 2007-07-05 15:31:00发表:

cash til payday loan cash til payday loan http://www.sdmentalhealth.org/Discussion/_disc4/0000320b.htm play roulette http://www.freewebs.com/casino-41/roulette-2.html roulette gambling quick payday loan quick payday loan http://www.msd.k12.or.us/schools/mhs/AlumDiscuss/000012ea.htm faxless payday loan http://www.pelicanpointe.net/_disc1/00001c86.htm faxless payday loan free keno games video keno http://www.freewebs.com/casino-49/keno-5.html

71.238.71.* 于 2007-07-05 12:02:12发表:

http://www.freewebs.com/casino-89/casino-3.html online casino casino on net http://www.cloeonline.com/_disc3/000000f1.htm bad debt loan payday bad debt loan payday roulette online http://www.freewebs.com/casino-31/roulette-4.html online roulette baccarat game casino baccarat http://www.freewebs.com/casino-89/baccarat-4.html fast cash payday loan fast cash payday loan http://www.impt.us/_disc1/0000014a.htm

0.0.0.* 于 2007-07-05 11:35:38发表:

java blackjack jack black http://www.freewebs.com/casino-49/blackjack-5.html free online craps free online craps http://www.freewebs.com/casino-49/craps-4.html http://www.freewebs.com/casino-41/blackjack-4.html casino blackjack play blackjack online free free casino free casino game http://www.freewebs.com/casino-41/casino-4.html play keno online play keno online http://www.freewebs.com/casino-49/keno-3.html

74.135.247.* 于 2007-07-05 11:09:26发表:

http://cahn.mnsu.edu/fall2001laugh/_disc3/000003ab.htm easy payday loan easy payday loan http://www.section-three.com/discgroup/_disc/00000f61.htm payday cash advance payday cash advance free craps http://www.freewebs.com/casino-49/craps-1.html how to play craps casino games http://www.freewebs.com/casino-97/casino-6.html las vegas casino keno online video keno http://www.freewebs.com/casino-49/keno-7.html

0.0.0.* 于 2007-07-05 11:02:57发表:

craps table casino craps http://www.freewebs.com/casino-60/craps-4.html cash advance paydayloans cash advance paydayloans http://poolfence.com/discussion/_disc1/00003ffb.htm gambling online casino http://www.freewebs.com/casino-274/casino-2.html http://www.freewebs.com/casino-919/casino-2.html jouez au casino en ligne casinos http://www.freewebs.com/casino-351/casino-2.html meilleures promotions en ligne meilleures promotions en ligne

210.94.108.* 于 2007-07-05 10:33:40发表:

http://www.socialnetworkforseniors.com/Poetry/00000050.htm payday loan payday loan http://www.freewebs.com/casino-49/blackjack-2.html online blackjack java blackjack 7 card stud seven card stud http://www.freewebs.com/casino-41/card-stud-7.html online casino craps http://www.freewebs.com/casino-31/craps-1.html craps online 7 card stud http://www.freewebs.com/casino-41/card-stud-1.html seven card stud

74.192.233.* 于 2007-07-05 10:31:36发表:

payday loan personal payday loan personal http://www.smsannafrank.it/_disc1/00000032.htm free online baccarat baccarat game http://www.freewebs.com/casino-41/baccarat-4.html http://www.freewebs.com/casino-49/card-stud-4.html seven card stud 7 card stud payday loan 1000 payday loan 1000 http://www.amaranthys.com/_disc1/00002a14.htm baccarat online free online baccarat http://www.freewebs.com/casino-49/baccarat-4.html

217.9.231.* 于 2007-07-05 10:29:55发表:

bad debt loan payday http://www.kafd.dk/_disc3/0000116c.htm bad debt loan payday sonic payday loan sonic payday loan http://www.ryangoodson.com/disc1/00000d6c.htm fast payday loan http://www.ruthiesarc.org/_disc2/00004d55.htm fast payday loan play blackjack blackjack online http://www.freewebs.com/casino-49/blackjack-7.html vegas casino casino games http://www.freewebs.com/casino-41/casino-7.html

24.154.148.* 于 2007-07-05 10:09:08发表:

casino fran?is gambling http://www.freewebs.com/casino-279/casino-3.html gambling gambling http://www.freewebs.com/casino-781/casino-3.html http://www.bernhardnordh.nu/_disk6/000018a1.htm cash til payday loan cash til payday loan craps table http://www.freewebs.com/casino-60/craps-2.html rules of craps blackjack odds blackjack odds http://www.freewebs.com/casino-60/blackjack-2.html

58.1.124.* 于 2007-07-05 09:39:23发表:

bad credit payday loan http://www.sticknrudder.net/myweb5/TW/00000794.htm bad credit payday loan http://www.freewebs.com/casino-44/craps-1.html craps game craps rules online casino slots free slots machine game http://www.freewebs.com/casino-45/slots-4.html http://nc-code.com/_disc2/000007bd.htm payday cash advance payday cash advance payday loan http://www.hcctustin.com/Prayer/DiscussionBoard/000000e5.htm payday loan

0.0.0.* 于 2007-07-05 09:36:54发表:

http://www.haime.com.ar/_disc1/00000dcd.htm fast cash payday loan fast cash payday loan http://www.freewebs.com/casino-49/blackjack-6.html blackjack gambling play blackjack online blogspot.com loan payday site http://detroit.originalchurchofgod.net/_prayer_req/000004cd.htm blogspot.com loan payday site payday cash loan payday cash loan http://www.troyh.com/Troysblog/00000058.htm play craps http://www.freewebs.com/casino-49/craps-6.html online craps

70.185.217.* 于 2007-07-05 09:30:01发表:

payday cash loan payday cash loan http://www.webpagedesignco.com/_greenhills/0000495d.htm http://www.freewebs.com/casino-41/roulette-4.html online roulette game roulette game blackjack gambling http://www.freewebs.com/casino-41/blackjack-2.html blackjack gambling http://www.freewebs.com/casino-41/slots-2.html free slots free slots machine instant faxless payday loan http://www.scagliotti.net/_disc1/000019ed.htm instant faxless payday loan

68.226.180.* 于 2007-07-05 09:29:45发表:

http://www.freewebs.com/casino-60/slots-2.html play slots play slots http://www.freewebs.com/casino-880/casino-1.html bonus de casino en ligne bonus de casino en ligne top promotions en ligne http://www.freewebs.com/casino-821/casino-2.html top promotions en ligne jouez au casino meilleur casino en ligne http://www.freewebs.com/casino-466/casino-3.html http://www.freewebs.com/casino-49/casino-5.html online casino gambling free casino games

74.52.206.* 于 2007-07-05 09:29:41发表:

casino roulette http://www.freewebs.com/casino-41/roulette-5.html casino roulette http://www.freewebs.com/casino-41/craps-5.html play craps play craps fast cash payday loan http://www.socialnetworkforseniors.com/Poetry/00000051.htm fast cash payday loan online craps free online craps http://www.freewebs.com/casino-76/craps-2.html fax payday loan http://www.mescoelectricalsupply.com/_disc3/00002996.htm fax payday loan

72.232.63.* 于 2007-07-04 20:07:08发表:

72.232.63.* 于 2007-07-04 20:06:39发表:

72.232.63.* 于 2007-07-04 20:05:32发表:

72.232.63.* 于 2007-07-04 20:05:03发表:

Linux操作系统内核模块与用户程序对比

共有 2222 条评论

频道文章

最新教程

随机推荐