原文地址：http://blog.csdn.net/geekcome/article/details/6398414

系統(tǒng)調(diào)用是一個(gè)軟中斷莽使，中斷號(hào)是0x80惫皱，它是上層應(yīng)用程序與Linux系統(tǒng)內(nèi)核進(jìn)行交互通信的唯一接口臀栈。

這個(gè)中斷的設(shè)置在kernel/sched.c中441行函數(shù)中

[cpp]view plaincopy

void?sched_init(void)??

{??

int?i;??

struct?desc_struct?*?p;??

if?(sizeof(struct?sigaction)?!=?16)??

panic("Struct?sigaction?MUST?be?16?bytes");??

????set_tss_desc(gdt+FIRST_TSS_ENTRY,&(init_task.task.tss));??

????set_ldt_desc(gdt+FIRST_LDT_ENTRY,&(init_task.task.ldt));??

????p?=?gdt+2+FIRST_TSS_ENTRY;??

for(i=1;i

????????task[i]?=?NULL;??

????????p->a=p->b=0;??

????????p++;??

????????p->a=p->b=0;??

????????p++;??

????}??

/*?Clear?NT,?so?that?we?won't?have?troubles?with?that?later?on?*/??

__asm__("pushfl?;?andl?$0xffffbfff,(%esp)?;?popfl");??

????ltr(0);??

????lldt(0);??

outb_p(0x36,0x43);/*?binary,?mode?3,?LSB/MSB,?ch?0?*/??

outb_p(LATCH?&?0xff?,?0x40);/*?LSB?*/??

outb(LATCH?>>?8?,?0x40);/*?MSB?*/??

????set_intr_gate(0x20,&timer_interrupt);??

????outb(inb_p(0x21)&~0x01,0x21);??

????set_system_gate(0x80,&system_call);??

}??

最后一句就將0x80中斷與system_call（系統(tǒng)調(diào)用）聯(lián)系起來隅居。

通過int 0x80祖灰，就可使用內(nèi)核資源尿招。不過诀豁，通常應(yīng)用程序都是使用具有標(biāo)準(zhǔn)接口定義的C函數(shù)庫間接的使用內(nèi)核的系統(tǒng)調(diào)用窄刘，即應(yīng)用程序調(diào)用C函數(shù)庫中的函數(shù)，C函數(shù)庫中再通過int 0x80進(jìn)行系統(tǒng)調(diào)用舷胜。

所以娩践，系統(tǒng)調(diào)用過程是這樣的：

應(yīng)用程序調(diào)用libc中的函數(shù)－>libc中的函數(shù)引用系統(tǒng)調(diào)用宏－>系統(tǒng)調(diào)用宏中使用int 0x80完成系統(tǒng)調(diào)用并返回

下面是sys_call_table的定義文件

位于./include/sys.h

[cpp]view plaincopy

extern?int?sys_setup?();????//?系統(tǒng)啟動(dòng)初始化設(shè)置函數(shù)。?(kernel/blk_drv/hd.c,71)??

extern?int?sys_exit?();?????//?程序退出烹骨。?(kernel/exit.c,?137)??

extern?int?sys_fork?();?????//?創(chuàng)建進(jìn)程翻伺。?(kernel/system_call.s,?208)??

extern?int?sys_read?();?????//?讀文件。?(fs/read_write.c,?55)??

extern?int?sys_write?();????//?寫文件沮焕。?(fs/read_write.c,?83)??

extern?int?sys_open?();?????//?打開文件吨岭。?(fs/open.c,?138)??

extern?int?sys_close?();????//?關(guān)閉文件。?(fs/open.c,?192)??

extern?int?sys_waitpid?();??//?等待進(jìn)程終止峦树。?(kernel/exit.c,?142)??

extern?int?sys_creat?();????//?創(chuàng)建文件辣辫。?(fs/open.c,?187)??

extern?int?sys_link?();?????//?創(chuàng)建一個(gè)文件的硬連接旦事。?(fs/namei.c,?721)??

extern?int?sys_unlink?();???//?刪除一個(gè)文件名(或刪除文件)。?(fs/namei.c,?663)??

extern?int?sys_execve?();???//?執(zhí)行程序急灭。?(kernel/system_call.s,?200)??

extern?int?sys_chdir?();????//?更改當(dāng)前目錄姐浮。?(fs/open.c,?75)??

extern?int?sys_time?();?????//?取當(dāng)前時(shí)間。?(kernel/sys.c,?102)??

extern?int?sys_mknod?();????//?建立塊/字符特殊文件葬馋。?(fs/namei.c,?412)??

extern?int?sys_chmod?();????//?修改文件屬性卖鲤。?(fs/open.c,?105)??

extern?int?sys_chown?();????//?修改文件宿主和所屬組。?(fs/open.c,?121)??

extern?int?sys_break?();????//?(-kernel/sys.c,?21)??

extern?int?sys_stat?();?????//?使用路徑名取文件的狀態(tài)信息畴嘶。?(fs/stat.c,?36)??

extern?int?sys_lseek?();????//?重新定位讀/寫文件偏移扫尖。?(fs/read_write.c,?25)??

extern?int?sys_getpid?();???//?取進(jìn)程id。?(kernel/sched.c,?348)??

extern?int?sys_mount?();????//?安裝文件系統(tǒng)掠廓。?(fs/super.c,?200)??

extern?int?sys_umount?();???//?卸載文件系統(tǒng)。?(fs/super.c,?167)??

extern?int?sys_setuid?();???//?設(shè)置進(jìn)程用戶id甩恼。?(kernel/sys.c,?143)??

extern?int?sys_getuid?();???//?取進(jìn)程用戶id蟀瞧。?(kernel/sched.c,?358)??

extern?int?sys_stime?();????//?設(shè)置系統(tǒng)時(shí)間日期。?(-kernel/sys.c,?148)??

extern?int?sys_ptrace?();???//?程序調(diào)試条摸。?(-kernel/sys.c,?26)??

extern?int?sys_alarm?();????//?設(shè)置報(bào)警悦污。?(kernel/sched.c,?338)??

extern?int?sys_fstat?();????//?使用文件句柄取文件的狀態(tài)信息。(fs/stat.c,?47)??

extern?int?sys_pause?();????//?暫停進(jìn)程運(yùn)行钉蒲。?(kernel/sched.c,?144)??

extern?int?sys_utime?();????//?改變文件的訪問和修改時(shí)間切端。?(fs/open.c,?24)??

extern?int?sys_stty?();?????//?修改終端行設(shè)置。?(-kernel/sys.c,?31)??

extern?int?sys_gtty?();?????//?取終端行設(shè)置信息顷啼。?(-kernel/sys.c,?36)??

extern?int?sys_access?();???//?檢查用戶對(duì)一個(gè)文件的訪問權(quán)限踏枣。(fs/open.c,?47)??

extern?int?sys_nice?();?????//?設(shè)置進(jìn)程執(zhí)行優(yōu)先權(quán)。?(kernel/sched.c,?378)??

extern?int?sys_ftime?();????//?取日期和時(shí)間钙蒙。?(-kernel/sys.c,16)??

extern?int?sys_sync?();?????//?同步高速緩沖與設(shè)備中數(shù)據(jù)茵瀑。?(fs/buffer.c,?44)??

extern?int?sys_kill?();?????//?終止一個(gè)進(jìn)程。?(kernel/exit.c,?60)??

extern?int?sys_rename?();???//?更改文件名躬厌。?(-kernel/sys.c,?41)??

extern?int?sys_mkdir?();????//?創(chuàng)建目錄马昨。?(fs/namei.c,?463)??

extern?int?sys_rmdir?();????//?刪除目錄。?(fs/namei.c,?587)??

extern?int?sys_dup?();??????//?復(fù)制文件句柄扛施。?(fs/fcntl.c,?42)??

extern?int?sys_pipe?();?????//?創(chuàng)建管道鸿捧。?(fs/pipe.c,?71)??

extern?int?sys_times?();????//?取運(yùn)行時(shí)間。?(kernel/sys.c,?156)??

extern?int?sys_prof?();?????//?程序執(zhí)行時(shí)間區(qū)域疙渣。?(-kernel/sys.c,?46)??

extern?int?sys_brk?();??????//?修改數(shù)據(jù)段長(zhǎng)度匙奴。?(kernel/sys.c,?168)??

extern?int?sys_setgid?();???//?設(shè)置進(jìn)程組id。?(kernel/sys.c,?72)??

extern?int?sys_getgid?();???//?取進(jìn)程組id昌阿。?(kernel/sched.c,?368)??

extern?int?sys_signal?();???//?信號(hào)處理饥脑。?(kernel/signal.c,?48)??

extern?int?sys_geteuid?();??//?取進(jìn)程有效用戶id恳邀。?(kenrl/sched.c,?363)??

extern?int?sys_getegid?();??//?取進(jìn)程有效組id。?(kenrl/sched.c,?373)??

extern?int?sys_acct?();?????//?進(jìn)程記帳灶轰。?(-kernel/sys.c,?77)??

extern?int?sys_phys?();?????//?(-kernel/sys.c,?82)??

extern?int?sys_lock?();?????//?(-kernel/sys.c,?87)??

extern?int?sys_ioctl?();????//?設(shè)備控制谣沸。?(fs/ioctl.c,?30)??

extern?int?sys_fcntl?();????//?文件句柄操作。?(fs/fcntl.c,?47)??

extern?int?sys_mpx?();??????//?(-kernel/sys.c,?92)??

extern?int?sys_setpgid?();??//?設(shè)置進(jìn)程組id笋颤。?(kernel/sys.c,?181)??

extern?int?sys_ulimit?();???//?(-kernel/sys.c,?97)??

extern?int?sys_uname?();????//?顯示系統(tǒng)信息乳附。?(kernel/sys.c,?216)??

extern?int?sys_umask?();????//?取默認(rèn)文件創(chuàng)建屬性碼。?(kernel/sys.c,?230)??

extern?int?sys_chroot?();???//?改變根系統(tǒng)伴澄。?(fs/open.c,?90)??

extern?int?sys_ustat?();????//?取文件系統(tǒng)信息赋除。?(fs/open.c,?19)??

extern?int?sys_dup2?();?????//?復(fù)制文件句柄。?(fs/fcntl.c,?36)??

extern?int?sys_getppid?();??//?取父進(jìn)程id非凌。?(kernel/sched.c,?353)??

extern?int?sys_getpgrp?();??//?取進(jìn)程組id举农，等于getpgid(0)。(kernel/sys.c,?201)??

extern?int?sys_setsid?();???//?在新會(huì)話中運(yùn)行程序敞嗡。?(kernel/sys.c,?206)??

extern?int?sys_sigaction?();????//?改變信號(hào)處理過程颁糟。?(kernel/signal.c,?63)??

extern?int?sys_sgetmask?();?//?取信號(hào)屏蔽碼。?(kernel/signal.c,?15)??

extern?int?sys_ssetmask?();?//?設(shè)置信號(hào)屏蔽碼喉悴。?(kernel/signal.c,?20)??

extern?int?sys_setreuid?();?//?設(shè)置真實(shí)與/或有效用戶id棱貌。?(kernel/sys.c,118)??

extern?int?sys_setregid?();?//?設(shè)置真實(shí)與/或有效組id。?(kernel/sys.c,?51)??

//?系統(tǒng)調(diào)用函數(shù)指針表箕肃。用于系統(tǒng)調(diào)用中斷處理程序(int?0x80)婚脱，作為跳轉(zhuǎn)表。??

fn_ptr?sys_call_table[]?=?{?sys_setup,?sys_exit,?sys_fork,?sys_read,??

??sys_write,?sys_open,?sys_close,?sys_waitpid,?sys_creat,?sys_link,??

??sys_unlink,?sys_execve,?sys_chdir,?sys_time,?sys_mknod,?sys_chmod,??

??sys_chown,?sys_break,?sys_stat,?sys_lseek,?sys_getpid,?sys_mount,??

??sys_umount,?sys_setuid,?sys_getuid,?sys_stime,?sys_ptrace,?sys_alarm,??

??sys_fstat,?sys_pause,?sys_utime,?sys_stty,?sys_gtty,?sys_access,??

??sys_nice,?sys_ftime,?sys_sync,?sys_kill,?sys_rename,?sys_mkdir,??

??sys_rmdir,?sys_dup,?sys_pipe,?sys_times,?sys_prof,?sys_brk,?sys_setgid,??

??sys_getgid,?sys_signal,?sys_geteuid,?sys_getegid,?sys_acct,?sys_phys,??

??sys_lock,?sys_ioctl,?sys_fcntl,?sys_mpx,?sys_setpgid,?sys_ulimit,??

??sys_uname,?sys_umask,?sys_chroot,?sys_ustat,?sys_dup2,?sys_getppid,??

??sys_getpgrp,?sys_setsid,?sys_sigaction,?sys_sgetmask,?sys_ssetmask,??

??sys_setreuid,?sys_setregid??

};??

其中sys_call_table的類型是fn_ptr類型勺像，其中sys_call_table[0]元素為sys_setup,它的類型是fn_ptr類型障贸，它實(shí)際上是函數(shù)sys_setup的

入口地址。

它的定義如下：

typedef int (*fn_ptr) (); // 定義函數(shù)指針類型吟宦。

下面的實(shí)例代碼有助于理解函數(shù)指針：

[cpp]view plaincopy

#include??

typedef?int?(*MyFunc)();??

MyFunc?Func1;??

int?Func2()??

{??

????printf("This?is?a?sample?output!/n");??

????return?0;??

}??

int?main()??

{??

????Func1=Func2;??

????//Func2();??

????//(*Func1)();??

????printf("%x/n",(*Func1));??

????printf("%x/n",Func2);??

????return?0;??

}??

system_call系統(tǒng)調(diào)用入口函數(shù)

[cpp]view plaincopy

####?int?0x80?--linux?系統(tǒng)調(diào)用入口點(diǎn)(調(diào)用中斷int?0x80惹想，eax?中是調(diào)用號(hào))。??

.align?2??

_system_call:??

cmpl?$nr_system_calls-1,%eax?#?調(diào)用號(hào)如果超出范圍的話就在eax?中置-1?并退出督函。??

ja?bad_sys_call??

push?%ds?#?保存原段寄存器值嘀粱。??

push?%es??

push?%fs??

pushl?%edx?#?ebx,ecx,edx?中放著系統(tǒng)調(diào)用相應(yīng)的C?語言函數(shù)的調(diào)用參數(shù)。??

pushl?%ecx?#?push?%ebx,%ecx,%edx?as?parameters??

pushl?%ebx?#?to?the?system?call??

movl?$0x10,%edx?#?set?up?ds,es?to?kernel?space??

mov?%dx,%ds?#?ds,es?指向內(nèi)核數(shù)據(jù)段(全局描述符表中數(shù)據(jù)段描述符)辰狡。??

mov?%dx,%es??

movl?$0x17,%edx?#?fs?points?to?local?data?space??

mov?%dx,%fs?#?fs?指向局部數(shù)據(jù)段(局部描述符表中數(shù)據(jù)段描述符)锋叨。??

#?下面這句操作數(shù)的含義是：調(diào)用地址?=?_sys_call_table?+?%eax?*?4。參見列表后的說明宛篇。??

#?對(duì)應(yīng)的C?程序中的sys_call_table?在include/linux/sys.h?中娃磺，其中定義了一個(gè)包括72?個(gè)??

#?系統(tǒng)調(diào)用C?處理函數(shù)的地址數(shù)組表。??

call?_sys_call_table(,%eax,4)??

pushl?%eax?#?把系統(tǒng)調(diào)用號(hào)入棧叫倍。??

movl?_current,%eax?#?取當(dāng)前任務(wù)（進(jìn)程）數(shù)據(jù)結(jié)構(gòu)地址??eax偷卧。??

#?下面97-100?行查看當(dāng)前任務(wù)的運(yùn)行狀態(tài)豺瘤。如果不在就緒狀態(tài)(state?不等于0)就去執(zhí)行調(diào)度程序。??

#?如果該任務(wù)在就緒狀態(tài)但counter[??]值等于0听诸，則也去執(zhí)行調(diào)度程序坐求。??

cmpl?$0,state(%eax)?#?state??

jne?reschedule??

cmpl?$0,counter(%eax)?#?counter??

je?reschedule??

#?以下這段代碼執(zhí)行從系統(tǒng)調(diào)用C?函數(shù)返回后，對(duì)信號(hào)量進(jìn)行識(shí)別處理晌梨。??

ret_from_sys_call:??

#?首先判別當(dāng)前任務(wù)是否是初始任務(wù)task0桥嗤，如果是則不必對(duì)其進(jìn)行信號(hào)量方面的處理，直接返回仔蝌。??

#?103?行上的_task?對(duì)應(yīng)C?程序中的task[]數(shù)組泛领，直接引用task?相當(dāng)于引用task[0]。??

movl?_current,%eax?#?task[0]?cannot?have?signals??

cmpl?_task,%eax??

je?3f?#?向前(forward)跳轉(zhuǎn)到標(biāo)號(hào)3敛惊。??

#?通過對(duì)原調(diào)用程序代碼選擇符的檢查來判斷調(diào)用程序是否是超級(jí)用戶渊鞋。如果是超級(jí)用戶就直接??

#?退出中斷，否則需進(jìn)行信號(hào)量的處理瞧挤。這里比較選擇符是否為普通用戶代碼段的選擇符0x000f??

#?(RPL=3篓像，局部表，第1?個(gè)段(代碼段))皿伺，如果不是則跳轉(zhuǎn)退出中斷程序。??

cmpw?$0x0f,CS(%esp)?#?was?old?code?segment?supervisor????

jne?3f??

#?如果原堆棧段選擇符不為0x17（也即原堆棧不在用戶數(shù)據(jù)段中）盒粮，則也退出鸵鸥。??

cmpw?$0x17,OLDSS(%esp)?#?was?stack?segment?=?0x17????

jne?3f??

#?下面這段代碼（109-120）的用途是首先取當(dāng)前任務(wù)結(jié)構(gòu)中的信號(hào)位圖(32?位，每位代表1?種信號(hào))丹皱，??

#?然后用任務(wù)結(jié)構(gòu)中的信號(hào)阻塞（屏蔽）碼妒穴，阻塞不允許的信號(hào)位，取得數(shù)值最小的信號(hào)值摊崭，再把??

#?原信號(hào)位圖中該信號(hào)對(duì)應(yīng)的位復(fù)位（置0）讼油，最后將該信號(hào)值作為參數(shù)之一調(diào)用do_signal()。??

#?do_signal()在（kernel/signal.c,82）中呢簸，其參數(shù)包括13?個(gè)入棧的信息矮台。??

movl?signal(%eax),%ebx?#?取信號(hào)位圖??ebx，每1?位代表1?種信號(hào)根时，共32?個(gè)信號(hào)瘦赫。??

movl?blocked(%eax),%ecx?#?取阻塞（屏蔽）信號(hào)位圖??ecx。??

notl?%ecx?#?每位取反蛤迎。??

andl?%ebx,%ecx?#?獲得許可的信號(hào)位圖确虱。??

bsfl?%ecx,%ecx?#?從低位（位0）開始掃描位圖，看是否有1?的位替裆，??

#?若有校辩，則ecx?保留該位的偏移值（即第幾位0-31）窘问。??

je?3f?#?如果沒有信號(hào)則向前跳轉(zhuǎn)退出。??

btrl?%ecx,%ebx?#?復(fù)位該信號(hào)（ebx?含有原signal?位圖）宜咒。??

movl?%ebx,signal(%eax)?#?重新保存signal?位圖信息??current->signal惠赫。??

incl?%ecx?#?將信號(hào)調(diào)整為從1?開始的數(shù)(1-32)。??

pushl?%ecx?#?信號(hào)值入棧作為調(diào)用do_signal?的參數(shù)之一荧呐。??

call?_do_signal?#?調(diào)用C?函數(shù)信號(hào)處理程序(kernel/signal.c,82)??

popl?%eax?#?彈出信號(hào)值汉形。??

3:?popl?%eax??

popl?%ebx??

popl?%ecx??

popl?%edx??

pop?%fs??

pop?%es??

pop?%ds??

iret??

./include/unistd.h文件中系統(tǒng)調(diào)用符號(hào)和調(diào)用號(hào)的對(duì)應(yīng)定義

[cpp]view plaincopy

//?以下是內(nèi)核實(shí)現(xiàn)的系統(tǒng)調(diào)用符號(hào)常數(shù)，用于作為系統(tǒng)調(diào)用函數(shù)表中的索引值倍阐。(?include/linux/sys.h?)??

#define?__NR_setup?0????????/*?used?only?by?init,?to?get?system?going?*/??

/*?__NR_setup?僅用于初始化概疆，以啟動(dòng)系統(tǒng)?*/??

#define?__NR_exit?1??

#define?__NR_fork?2??

#define?__NR_read?3??

#define?__NR_write?4??

#define?__NR_open?5??

#define?__NR_close?6??

#define?__NR_waitpid?7??

#define?__NR_creat?8??

#define?__NR_link?9??

#define?__NR_unlink?10??

#define?__NR_execve?11??

#define?__NR_chdir?12??

#define?__NR_time?13??

#define?__NR_mknod?14??

#define?__NR_chmod?15??

#define?__NR_chown?16??

#define?__NR_break?17??

#define?__NR_stat?18??

#define?__NR_lseek?19??

#define?__NR_getpid?20??

#define?__NR_mount?21??

#define?__NR_umount?22??

#define?__NR_setuid?23??

#define?__NR_getuid?24??

#define?__NR_stime?25??

#define?__NR_ptrace?26??

#define?__NR_alarm?27??

#define?__NR_fstat?28??

#define?__NR_pause?29??

#define?__NR_utime?30??

#define?__NR_stty?31??

#define?__NR_gtty?32??

#define?__NR_access?33??

#define?__NR_nice?34??

#define?__NR_ftime?35??

#define?__NR_sync?36??

#define?__NR_kill?37??

#define?__NR_rename?38??

#define?__NR_mkdir?39??

#define?__NR_rmdir?40??

#define?__NR_dup?41??

#define?__NR_pipe?42??

#define?__NR_times?43??

#define?__NR_prof?44??

#define?__NR_brk?45??

#define?__NR_setgid?46??

#define?__NR_getgid?47??

#define?__NR_signal?48??

#define?__NR_geteuid?49??

#define?__NR_getegid?50??

#define?__NR_acct?51??

#define?__NR_phys?52??

#define?__NR_lock?53??

#define?__NR_ioctl?54??

#define?__NR_fcntl?55??

#define?__NR_mpx?56??

#define?__NR_setpgid?57??

#define?__NR_ulimit?58??

#define?__NR_uname?59??

#define?__NR_umask?60??

#define?__NR_chroot?61??

#define?__NR_ustat?62??

#define?__NR_dup2?63??

#define?__NR_getppid?64??

#define?__NR_getpgrp?65??

#define?__NR_setsid?66??

#define?__NR_sigaction?67??

#define?__NR_sgetmask?68??

#define?__NR_ssetmask?69??

#define?__NR_setreuid?70??

#define?__NR_setregid?71??

這是一系列宏，它們的定義在unistd.h中峰搪，基本形式為＃define _NR_name value岔冀，name為系統(tǒng)函數(shù)名字，value是一個(gè)整數(shù)值概耻，是name所對(duì)應(yīng)的系統(tǒng)函數(shù)指針在sys_call_table中的偏移量使套。

系統(tǒng)調(diào)用宏也在本文件內(nèi)定義，采用內(nèi)聯(lián)匯編鞠柄，如下：

[cpp]view plaincopy

//?以下定義系統(tǒng)調(diào)用嵌入式匯編宏函數(shù)侦高。??

//?不帶參數(shù)的系統(tǒng)調(diào)用宏函數(shù)。type?name(void)厌杜。??

//?%0?-?eax(__res)奉呛，%1?-?eax(__NR_##name)。其中name?是系統(tǒng)調(diào)用的名稱夯尽，與?__NR_?組合形成上面??

//?的系統(tǒng)調(diào)用符號(hào)常數(shù)瞧壮，從而用來對(duì)系統(tǒng)調(diào)用表中函數(shù)指針尋址。??

//?返回：如果返回值大于等于0匙握，則返回該值咆槽，否則置出錯(cuò)號(hào)errno，并返回-1圈纺。??

#define?_syscall0(type,name)?/??

type?name(void)?/??

{?/??

long?__res;?/??

__asm__?volatile?(?"int?$0x80"?/????//?調(diào)用系統(tǒng)中斷0x80秦忿。??

:"=a"?(__res)?/?????//?返回值??eax(__res)。??

:""?(__NR_##name));?/???????????//?輸入為系統(tǒng)中斷調(diào)用號(hào)__NR_name蛾娶。??

??????if?(__res?>=?0)?/??????//?如果返回值>=0小渊，則直接返回該值。??

??????return?(type)?__res;?errno?=?-__res;?/????//?否則置出錯(cuò)號(hào)茫叭，并返回-1酬屉。??

??????return?-1;}??

//?有1?個(gè)參數(shù)的系統(tǒng)調(diào)用宏函數(shù)。type?name(atype?a)??

//?%0?-?eax(__res)，%1?-?eax(__NR_name)呐萨，%2?-?ebx(a)杀饵。??

#define?_syscall1(type,name,atype,a)?/??

type?name(atype?a)?/??

{?/??

long?__res;?/??

__asm__?volatile?(?"int?$0x80"?/??

:?"=a"?(__res)?/??

:?""?(__NR_##name),?"b"?((long)(a)));?/??

if?(__res?>=?0)?/??

return?(type)?__res;?/??

errno?=?-__res;?/??

return?-1;?/??

}??

//?有2?個(gè)參數(shù)的系統(tǒng)調(diào)用宏函數(shù)。type?name(atype?a,?btype?b)??

//?%0?-?eax(__res)谬擦，%1?-?eax(__NR_name)切距，%2?-?ebx(a)，%3?-?ecx(b)惨远。??

#define?_syscall2(type,name,atype,a,btype,b)?/??

type?name(atype?a,btype?b)?/??

{?/??

long?__res;?/??

__asm__?volatile?(?"int?$0x80"?/??

:?"=a"?(__res)?/??

:?""?(__NR_##name),?"b"?((long)(a)),?"c"?((long)(b)));?/??

if?(__res?>=?0)?/??

return?(type)?__res;?/??

errno?=?-__res;?/??

return?-1;?/??

}??

//?有3?個(gè)參數(shù)的系統(tǒng)調(diào)用宏函數(shù)谜悟。type?name(atype?a,?btype?b,?ctype?c)??

//?%0?-?eax(__res)，%1?-?eax(__NR_name)北秽，%2?-?ebx(a)葡幸，%3?-?ecx(b)，%4?-?edx(c)贺氓。??

#define?_syscall3(type,name,atype,a,btype,b,ctype,c)?/??

type?name(atype?a,btype?b,ctype?c)?/??

{?/??

long?__res;?/??

__asm__?volatile?(?"int?$0x80"?/??

:?"=a"?(__res)?/??

:?""?(__NR_##name),?"b"?((long)(a)),?"c"?((long)(b)),?"d"?((long)(c)));?/??

if?(__res>=0)?/??

return?(type)?__res;?/??

errno=-__res;?/??

return?-1;?/??

} ?