linux系統呼叫使用者態到核心態流程
阿新 • • 發佈:2018-12-26
Linux系統呼叫流程分析
一直很好奇系統呼叫的詳細過程,只簡單的瞭解系統呼叫是使用者與核心互動的藉口,看了幾天的內容,不知道從何下手開始寫,今天略有頭緒,做以簡單總結。
1, 什麼是系統呼叫。
系統呼叫:系統呼叫是作業系統為使用者提供的一系列API;系統呼叫將使用者的請求發給核心,核心執行完以後,將結果返回給使用者;
2, 一個系統呼叫的流程。
如上圖,是系統呼叫write()函式的呼叫過程,不難看出,在使用者開始呼叫系統呼叫時,觸發了軟中斷Int0X80。到這肯定有人疑問,為什麼中斷號是0X80,因為程式碼中把系統呼叫跟0X80繫結在一起。
中斷向量:一個記憶體單元,存放中斷處理程式入口地址和程式執行時所需處理機狀態字。
這裡不再深入講解向量表的生成,只需要知道每個中斷都有對應的中斷號並對應處理程式。
linux的中斷向量表:
a.0X80中斷號:
/* * 我們需要下面這些內嵌語句- 從核心空間建立程序(forking)將導致沒有寫時復 * 制(COPY ON WRITE)!!!直到一個執行execve 呼叫。這對堆疊可能帶來問題。處 * 理的方法是在fork()呼叫之後不讓main()使用任何堆疊。因此就不能有函式調 * 用- 這意味著fork 也要使用內嵌的程式碼,否則我們在從fork()退出時就要使用堆疊了。 * * 實際上只有pause 和fork 需要使用內嵌方式,以保證從main()中不會弄亂堆疊, * 但是我們同時還定義了其它一些函式。 */ /* _syscall0 是unistd.h 中的內嵌巨集程式碼。以嵌入彙編的形式呼叫Linux 的系統呼叫中斷0x80。 Linux 的系統呼叫中斷0x80,該中斷是所有系統呼叫的入口。 syscall0 名稱中最後的0 表示無引數,1 表示1 個引數。 */ static _inline _syscall0(int,fork) static _inline _syscall0(int,pause) // int pause()系統呼叫:暫停程序的執行,直到收到一個訊號。 static _inline _syscall1(int,setup,void *,BIOS) // int setup(void * BIOS)系統呼叫,僅用於linux 初始化(僅在這個程式中被呼叫)。 static _inline _syscall0(int,sync) // int sync()系統呼叫:更新檔案系統。 #include <linux/tty.h> // tty 標頭檔案,定義了有關tty_io,序列通訊方面的 // 引數、常數。 #include <linux/sched.h> // 排程程式標頭檔案,定義了任務結構task_struct、第1 個 // 初始任務的資料。還有一些以巨集的形式定義的有關描述符 // 引數設定和獲取的嵌入式彙編函式程式。 #include <linux/head.h> // head 標頭檔案,定義了段描述符的簡單結構, // 和幾個選擇符常量。 #include <asm/system.h> // 系統標頭檔案。以巨集的形式定義了許多有關設定或修改 // 描述符/中斷門等的嵌入式彙編子程式。 #include <asm/io.h> // io 標頭檔案。以巨集的嵌入彙編程式形式定義對io 端 // 口操作的函式。 #include <stddef.h> // 標準定義標頭檔案。定義了NULL, offsetof(TYPE, MEMBER)。 #include <stdarg.h> // 標準引數標頭檔案。以巨集的形式定義變數引數列表。主要說 // 明瞭-個型別(va_list)和三個巨集(va_start, va_arg 和 // va_end),vsprintf、vprintf、vfprintf。 #include <fcntl.h> // 檔案控制標頭檔案。用於檔案及其描述符的操作控制常數 // 符號的定義。 #include <sys/types.h>// 型別標頭檔案。定義了基本的系統資料型別。 #include <linux/fs.h>// 檔案系統標頭檔案。定義檔案表結構 //(file,buffer_head,m_inode 等)。 static char printbuf[1024]; extern int vsprintf(); // 送格式化輸出到一字串中(在kernel/vsprintf.c)。 extern void init(void); // 函式原形,初始化(在後面)。 extern void blk_dev_init(void); // 塊裝置初始化子程式(kernel/blk_drv/ll_rw_blk.c) extern void chr_dev_init(void); // 字元裝置初始化(kernel/chr_drv/tty_io.c) extern void hd_init(void); // 硬碟初始化程式(kernel/blk_drv/hd.c) extern void floppy_init(void); // 軟碟機初始化程式(kernel/blk_drv/floppy.c) extern void mem_init(long start, long end); // 記憶體管理初始化(mm/memory.c) extern long rd_init(long mem_start, int length); //虛擬盤初始化(kernel/blk_drv/ramdisk.c) extern long kernel_mktime(struct tm * tm); // 建立核心時間(秒)。 extern long startup_time; // 核心啟動時間(開機時間)(秒)。 /* * 以下這些資料是由setup.s 程式在引導時間設定的。 */ #define EXT_MEM_K (*(unsigned short *)0x90002) // 1M 以後的擴充套件記憶體大小(KB)。 #define DRIVE_INFO (*(struct drive_info *)0x90080) // 硬碟引數表基址。 #define ORIG_ROOT_DEV (*(unsigned short *)0x901FC) // 根檔案系統所在裝置號。 /* * 是啊,是啊,下面這段程式很差勁,但我不知道如何正確地實現,而且好象 * 它還能執行。如果有關於實時時鐘更多的資料,那我很感興趣。這些都是試 * 探出來的,以及看了一些bios 程式,呵! */ // 這段巨集讀取CMOS 實時時鐘資訊。 // 0x70 是寫埠號,0x80|addr 是要讀取的CMOS 記憶體地址。 // 0x71 是讀埠號。 /* #define CMOS_READ(addr) ({ \ outb_p(0x80|addr,0x70); \ inb_p(0x71); \ })*/ _inline unsigned char CMOS_READ(unsigned char addr) { outb_p(addr,0x70); return inb_p(0x71); }
下面是_system_call的彙編程式碼(asm.S):
_system_call:
cmp eax,nr_system_calls-1 ;// 呼叫號如果超出範圍的話就在eax 中置-1 並退出。
ja bad_sys_call
push ds ;// 儲存原段暫存器值。
push es
push fs
push edx ;// ebx,ecx,edx 中放著系統呼叫相應的C 語言函式的呼叫引數。
push ecx ;// push %ebx,%ecx,%edx as parameters
push ebx ;// to the system call
mov edx,10h ;// set up ds,es to kernel space
mov ds,dx ;// ds,es 指向核心資料段(全域性描述符表中資料段描述符)。
mov es,dx
mov edx,17h ;// fs points to local data space
mov fs,dx ;// fs 指向區域性資料段(區域性描述符表中資料段描述符)。
;// 下面這句運算元的含義是:呼叫地址 = _sys_call_table + %eax * 4。參見列表後的說明。
;// 對應的C 程式中的sys_call_table 在include/linux/sys.h 中,其中定義了一個包括72 個
;// 系統呼叫C 處理函式的地址陣列表。
call [_sys_call_table+eax*4]
push eax ;// 把系統呼叫號入棧。
mov eax,_current ;// 取當前任務(程序)資料結構地址??eax。
;// 下面97-100 行檢視當前任務的執行狀態。如果不在就緒狀態(state 不等於0)就去執行排程程式。
;// 如果該任務在就緒狀態但counter[??]值等於0,則也去執行排程程式。
cmp dword ptr [state+eax],0 ;// state
jne reschedule
cmp dword ptr [counter+eax],0 ;// counter
je reschedule
b.現場保護與恢復
因為使用者態和核心態不共用一個堆疊,所以使用者態呼叫系統呼叫時,得先儲存使用者態的資訊到暫存器,然後切入到核心態,將暫存器中的資訊拷貝到核心棧開始執行,執行結束後,還原之前使用者態的狀態讓使用者態繼續往下執行。
使用者態程式通過ebx,ecx,edx等暫存器,傳遞函式引數給系統呼叫,ebx,ecx,edx等暫存器通過SAVE_ALL巨集壓到核心棧。
系統呼叫結束之後,RESTORE_ALL巨集把SAVE_ALL巨集壓入的暫存器反向彈出,以用於恢復現場。
c.呼叫系統呼叫表
syscall_handler_t *sys_call_table[] = {
[ __NR_restart_syscall ] = (syscall_handler_t *) sys_restart_syscall,
[ __NR_exit ] = (syscall_handler_t *) sys_exit,
[ __NR_fork ] = (syscall_handler_t *) sys_fork,
[ __NR_read ] = (syscall_handler_t *) sys_read,
[ __NR_write ] = (syscall_handler_t *) sys_write,
/* These three are declared differently in asm/unistd.h */
[ __NR_open ] = (syscall_handler_t *) sys_open,
[ __NR_close ] = (syscall_handler_t *) sys_close,
[ __NR_creat ] = (syscall_handler_t *) sys_creat,
[ __NR_link ] = (syscall_handler_t *) sys_link,
[ __NR_unlink ] = (syscall_handler_t *) sys_unlink,
[ __NR_execve ] = (syscall_handler_t *) sys_execve,
/* declared differently in kern_util.h */
[ __NR_chdir ] = (syscall_handler_t *) sys_chdir,
[ __NR_time ] = um_time,
[ __NR_mknod ] = (syscall_handler_t *) sys_mknod,
[ __NR_chmod ] = (syscall_handler_t *) sys_chmod,
[ __NR_lchown ] = (syscall_handler_t *) sys_lchown16,
[ __NR_lseek ] = (syscall_handler_t *) sys_lseek,
[ __NR_getpid ] = (syscall_handler_t *) sys_getpid,
[ __NR_mount ] = um_mount,
[ __NR_setuid ] = (syscall_handler_t *) sys_setuid16,
[ __NR_getuid ] = (syscall_handler_t *) sys_getuid16,
[ __NR_ptrace ] = (syscall_handler_t *) sys_ptrace,
[ __NR_alarm ] = (syscall_handler_t *) sys_alarm,
[ __NR_pause ] = (syscall_handler_t *) sys_pause,
[ __NR_utime ] = (syscall_handler_t *) sys_utime,
[ __NR_access ] = (syscall_handler_t *) sys_access,
[ __NR_sync ] = (syscall_handler_t *) sys_sync,
[ __NR_kill ] = (syscall_handler_t *) sys_kill,
[ __NR_rename ] = (syscall_handler_t *) sys_rename,
[ __NR_mkdir ] = (syscall_handler_t *) sys_mkdir,
[ __NR_rmdir ] = (syscall_handler_t *) sys_rmdir,
/* Declared differently in asm/unistd.h */
[ __NR_dup ] = (syscall_handler_t *) sys_dup,
[ __NR_pipe ] = (syscall_handler_t *) sys_pipe,
[ __NR_times ] = (syscall_handler_t *) sys_times,
[ __NR_brk ] = (syscall_handler_t *) sys_brk,
[ __NR_setgid ] = (syscall_handler_t *) sys_setgid16,
[ __NR_getgid ] = (syscall_handler_t *) sys_getgid16,
[ __NR_geteuid ] = (syscall_handler_t *) sys_geteuid16,
[ __NR_getegid ] = (syscall_handler_t *) sys_getegid16,
[ __NR_acct ] = (syscall_handler_t *) sys_acct,
[ __NR_umount2 ] = (syscall_handler_t *) sys_umount,
[ __NR_ioctl ] = (syscall_handler_t *) sys_ioctl,
[ __NR_fcntl ] = (syscall_handler_t *) sys_fcntl,
[ __NR_setpgid ] = (syscall_handler_t *) sys_setpgid,
[ __NR_umask ] = (syscall_handler_t *) sys_umask,
[ __NR_chroot ] = (syscall_handler_t *) sys_chroot,
[ __NR_ustat ] = (syscall_handler_t *) sys_ustat,
[ __NR_dup2 ] = (syscall_handler_t *) sys_dup2,
[ __NR_getppid ] = (syscall_handler_t *) sys_getppid,
[ __NR_getpgrp ] = (syscall_handler_t *) sys_getpgrp,
[ __NR_setsid ] = (syscall_handler_t *) sys_setsid,
[ __NR_setreuid ] = (syscall_handler_t *) sys_setreuid16,
[ __NR_setregid ] = (syscall_handler_t *) sys_setregid16,
[ __NR_sethostname ] = (syscall_handler_t *) sys_sethostname,
[ __NR_setrlimit ] = (syscall_handler_t *) sys_setrlimit,
[ __NR_getrlimit ] = (syscall_handler_t *) sys_old_getrlimit,
[ __NR_getrusage ] = (syscall_handler_t *) sys_getrusage,
[ __NR_gettimeofday ] = (syscall_handler_t *) sys_gettimeofday,
[ __NR_settimeofday ] = (syscall_handler_t *) sys_settimeofday,
[ __NR_getgroups ] = (syscall_handler_t *) sys_getgroups16,
[ __NR_setgroups ] = (syscall_handler_t *) sys_setgroups16,
[ __NR_symlink ] = (syscall_handler_t *) sys_symlink,
[ __NR_readlink ] = (syscall_handler_t *) sys_readlink,
[ __NR_uselib ] = (syscall_handler_t *) sys_uselib,
[ __NR_swapon ] = (syscall_handler_t *) sys_swapon,
[ __NR_reboot ] = (syscall_handler_t *) sys_reboot,
[ __NR_munmap ] = (syscall_handler_t *) sys_munmap,
[ __NR_truncate ] = (syscall_handler_t *) sys_truncate,
[ __NR_ftruncate ] = (syscall_handler_t *) sys_ftruncate,
[ __NR_fchmod ] = (syscall_handler_t *) sys_fchmod,
[ __NR_fchown ] = (syscall_handler_t *) sys_fchown16,
[ __NR_getpriority ] = (syscall_handler_t *) sys_getpriority,
[ __NR_setpriority ] = (syscall_handler_t *) sys_setpriority,
[ __NR_statfs ] = (syscall_handler_t *) sys_statfs,
[ __NR_fstatfs ] = (syscall_handler_t *) sys_fstatfs,
[ __NR_ioperm ] = (syscall_handler_t *) sys_ni_syscall,
[ __NR_syslog ] = (syscall_handler_t *) sys_syslog,
[ __NR_setitimer ] = (syscall_handler_t *) sys_setitimer,
[ __NR_getitimer ] = (syscall_handler_t *) sys_getitimer,
[ __NR_stat ] = (syscall_handler_t *) sys_newstat,
[ __NR_lstat ] = (syscall_handler_t *) sys_newlstat,
[ __NR_fstat ] = (syscall_handler_t *) sys_newfstat,
[ __NR_vhangup ] = (syscall_handler_t *) sys_vhangup,
[ __NR_wait4 ] = (syscall_handler_t *) sys_wait4,
[ __NR_swapoff ] = (syscall_handler_t *) sys_swapoff,
[ __NR_sysinfo ] = (syscall_handler_t *) sys_sysinfo,
[ __NR_fsync ] = (syscall_handler_t *) sys_fsync,
[ __NR_clone ] = (syscall_handler_t *) sys_clone,
[ __NR_setdomainname ] = (syscall_handler_t *) sys_setdomainname,
[ __NR_uname ] = (syscall_handler_t *) sys_newuname,
[ __NR_adjtimex ] = (syscall_handler_t *) sys_adjtimex,
[ __NR_mprotect ] = (syscall_handler_t *) sys_mprotect,
[ __NR_create_module ] = (syscall_handler_t *) sys_ni_syscall,
[ __NR_init_module ] = (syscall_handler_t *) sys_init_module,
[ __NR_delete_module ] = (syscall_handler_t *) sys_delete_module,
[ __NR_get_kernel_syms ] = (syscall_handler_t *) sys_ni_syscall,
[ __NR_quotactl ] = (syscall_handler_t *) sys_quotactl,
[ __NR_getpgid ] = (syscall_handler_t *) sys_getpgid,
[ __NR_fchdir ] = (syscall_handler_t *) sys_fchdir,
[ __NR_sysfs ] = (syscall_handler_t *) sys_sysfs,
[ __NR_personality ] = (syscall_handler_t *) sys_personality,
[ __NR_afs_syscall ] = (syscall_handler_t *) sys_ni_syscall,
[ __NR_setfsuid ] = (syscall_handler_t *) sys_setfsuid16,
[ __NR_setfsgid ] = (syscall_handler_t *) sys_setfsgid16,
[ __NR_getdents ] = (syscall_handler_t *) sys_getdents,
[ __NR_flock ] = (syscall_handler_t *) sys_flock,
[ __NR_msync ] = (syscall_handler_t *) sys_msync,
[ __NR_readv ] = (syscall_handler_t *) sys_readv,
[ __NR_writev ] = (syscall_handler_t *) sys_writev,
[ __NR_getsid ] = (syscall_handler_t *) sys_getsid,
[ __NR_fdatasync ] = (syscall_handler_t *) sys_fdatasync,
[ __NR__sysctl ] = (syscall_handler_t *) sys_sysctl,
[ __NR_mlock ] = (syscall_handler_t *) sys_mlock,
[ __NR_munlock ] = (syscall_handler_t *) sys_munlock,
[ __NR_mlockall ] = (syscall_handler_t *) sys_mlockall,
[ __NR_munlockall ] = (syscall_handler_t *) sys_munlockall,
[ __NR_sched_setparam ] = (syscall_handler_t *) sys_sched_setparam,
[ __NR_sched_getparam ] = (syscall_handler_t *) sys_sched_getparam,
[ __NR_sched_setscheduler ] = (syscall_handler_t *) sys_sched_setscheduler,
[ __NR_sched_getscheduler ] = (syscall_handler_t *) sys_sched_getscheduler,
[ __NR_sched_yield ] = (syscall_handler_t *) yield,
[ __NR_sched_get_priority_max ] = (syscall_handler_t *) sys_sched_get_priority_max,
[ __NR_sched_get_priority_min ] = (syscall_handler_t *) sys_sched_get_priority_min,
[ __NR_sched_rr_get_interval ] = (syscall_handler_t *) sys_sched_rr_get_interval,
[ __NR_nanosleep ] = (syscall_handler_t *) sys_nanosleep,
[ __NR_mremap ] = (syscall_handler_t *) sys_mremap,
[ __NR_setresuid ] = (syscall_handler_t *) sys_setresuid16,
[ __NR_getresuid ] = (syscall_handler_t *) sys_getresuid16,
[ __NR_query_module ] = (syscall_handler_t *) sys_ni_syscall,
[ __NR_poll ] = (syscall_handler_t *) sys_poll,
[ __NR_nfsservctl ] = (syscall_handler_t *) NFSSERVCTL,
[ __NR_setresgid ] = (syscall_handler_t *) sys_setresgid16,
[ __NR_getresgid ] = (syscall_handler_t *) sys_getresgid16,
[ __NR_prctl ] = (syscall_handler_t *) sys_prctl,
[ __NR_rt_sigreturn ] = (syscall_handler_t *) sys_rt_sigreturn,
[ __NR_rt_sigaction ] = (syscall_handler_t *) sys_rt_sigaction,
[ __NR_rt_sigprocmask ] = (syscall_handler_t *) sys_rt_sigprocmask,
[ __NR_rt_sigpending ] = (syscall_handler_t *) sys_rt_sigpending,
[ __NR_rt_sigtimedwait ] = (syscall_handler_t *) sys_rt_sigtimedwait,
[ __NR_rt_sigqueueinfo ] = (syscall_handler_t *) sys_rt_sigqueueinfo,
[ __NR_rt_sigsuspend ] = (syscall_handler_t *) sys_rt_sigsuspend,
[ __NR_pread64 ] = (syscall_handler_t *) sys_pread64,
[ __NR_pwrite64 ] = (syscall_handler_t *) sys_pwrite64,
[ __NR_chown ] = (syscall_handler_t *) sys_chown16,
[ __NR_getcwd ] = (syscall_handler_t *) sys_getcwd,
[ __NR_capget ] = (syscall_handler_t *) sys_capget,
[ __NR_capset ] = (syscall_handler_t *) sys_capset,
[ __NR_sigaltstack ] = (syscall_handler_t *) sys_sigaltstack,
[ __NR_sendfile ] = (syscall_handler_t *) sys_sendfile,
[ __NR_getpmsg ] = (syscall_handler_t *) sys_ni_syscall,
[ __NR_putpmsg ] = (syscall_handler_t *) sys_ni_syscall,
[ __NR_vfork ] = (syscall_handler_t *) sys_vfork,
[ __NR_getdents64 ] = (syscall_handler_t *) sys_getdents64,
[ __NR_gettid ] = (syscall_handler_t *) sys_gettid,
[ __NR_readahead ] = (syscall_handler_t *) sys_readahead,
[ __NR_setxattr ] = (syscall_handler_t *) sys_setxattr,
[ __NR_lsetxattr ] = (syscall_handler_t *) sys_lsetxattr,
[ __NR_fsetxattr ] = (syscall_handler_t *) sys_fsetxattr,
[ __NR_getxattr ] = (syscall_handler_t *) sys_getxattr,
[ __NR_lgetxattr ] = (syscall_handler_t *) sys_lgetxattr,
[ __NR_fgetxattr ] = (syscall_handler_t *) sys_fgetxattr,
[ __NR_listxattr ] = (syscall_handler_t *) sys_listxattr,
[ __NR_llistxattr ] = (syscall_handler_t *) sys_llistxattr,
[ __NR_flistxattr ] = (syscall_handler_t *) sys_flistxattr,
[ __NR_removexattr ] = (syscall_handler_t *) sys_removexattr,
[ __NR_lremovexattr ] = (syscall_handler_t *) sys_lremovexattr,
[ __NR_fremovexattr ] = (syscall_handler_t *) sys_fremovexattr,
[ __NR_tkill ] = (syscall_handler_t *) sys_tkill,
[ __NR_futex ] = (syscall_handler_t *) sys_futex,
[ __NR_sched_setaffinity ] = (syscall_handler_t *) sys_sched_setaffinity,
[ __NR_sched_getaffinity ] = (syscall_handler_t *) sys_sched_getaffinity,
[ __NR_io_setup ] = (syscall_handler_t *) sys_io_setup,
[ __NR_io_destroy ] = (syscall_handler_t *) sys_io_destroy,
[ __NR_io_getevents ] = (syscall_handler_t *) sys_io_getevents,
[ __NR_io_submit ] = (syscall_handler_t *) sys_io_submit,
[ __NR_io_cancel ] = (syscall_handler_t *) sys_io_cancel,
[ __NR_exit_group ] = (syscall_handler_t *) sys_exit_group,
[ __NR_lookup_dcookie ] = (syscall_handler_t *) sys_lookup_dcookie,
[ __NR_epoll_create ] = (syscall_handler_t *) sys_epoll_create,
[ __NR_epoll_ctl ] = (syscall_handler_t *) sys_epoll_ctl,
[ __NR_epoll_wait ] = (syscall_handler_t *) sys_epoll_wait,
[ __NR_set_tid_address ] = (syscall_handler_t *) sys_set_tid_address,
[ __NR_timer_create ] = (syscall_handler_t *) sys_timer_create,
[ __NR_timer_settime ] = (syscall_handler_t *) sys_timer_settime,
[ __NR_timer_gettime ] = (syscall_handler_t *) sys_timer_gettime,
[ __NR_timer_getoverrun ] = (syscall_handler_t *) sys_timer_getoverrun,
[ __NR_timer_delete ] = (syscall_handler_t *) sys_timer_delete,
[ __NR_clock_settime ] = (syscall_handler_t *) sys_clock_settime,
[ __NR_clock_gettime ] = (syscall_handler_t *) sys_clock_gettime,
[ __NR_clock_getres ] = (syscall_handler_t *) sys_clock_getres,
[ __NR_clock_nanosleep ] = (syscall_handler_t *) sys_clock_nanosleep,
[ __NR_statfs64 ] = (syscall_handler_t *) sys_statfs64,
[ __NR_fstatfs64 ] = (syscall_handler_t *) sys_fstatfs64,
[ __NR_tgkill ] = (syscall_handler_t *) sys_tgkill,
[ __NR_utimes ] = (syscall_handler_t *) sys_utimes,
[ __NR_fadvise64_64 ] = (syscall_handler_t *) sys_fadvise64_64,
[ __NR_vserver ] = (syscall_handler_t *) sys_vserver,
[ __NR_mbind ] = (syscall_handler_t *) sys_mbind,
[ __NR_get_mempolicy ] = (syscall_handler_t *) sys_get_mempolicy,
[ __NR_set_mempolicy ] = (syscall_handler_t *) sys_set_mempolicy,
[ __NR_mq_open ] = (syscall_handler_t *) sys_mq_open,
[ __NR_mq_unlink ] = (syscall_handler_t *) sys_mq_unlink,
[ __NR_mq_timedsend ] = (syscall_handler_t *) sys_mq_timedsend,
[ __NR_mq_timedreceive ] = (syscall_handler_t *) sys_mq_timedreceive,
[ __NR_mq_notify ] = (syscall_handler_t *) sys_mq_notify,
[ __NR_mq_getsetattr ] = (syscall_handler_t *) sys_mq_getsetattr,
[ __NR_sys_kexec_load ] = (syscall_handler_t *) sys_ni_syscall,
[ __NR_waitid ] = (syscall_handler_t *) sys_waitid,
[ 285 ] = (syscall_handler_t *) sys_ni_syscall,
[ __NR_add_key ] = (syscall_handler_t *) sys_add_key,
[ __NR_request_key ] = (syscall_handler_t *) sys_request_key,
[ __NR_keyctl ] = (syscall_handler_t *) sys_keyctl,
ARCH_SYSCALLS
[ LAST_SYSCALL + 1 ... NR_syscalls ] =
(syscall_handler_t *) sys_ni_syscall
};
從這裡會跳轉到具體的系統呼叫。
每個系統呼叫對應一個呼叫號(unistd.h)
#ifndef _ALPHA_UNISTD_H
#define _ALPHA_UNISTD_H
#define __NR_osf_syscall 0 /* not implemented */
#define __NR_exit 1
#define __NR_fork 2
#define __NR_read 3
#define __NR_write 4
#define __NR_osf_old_open 5 /* not implemented */
#define __NR_close 6
#define __NR_osf_wait4 7
#define __NR_osf_old_creat 8 /* not implemented */
#define __NR_link 9
#define __NR_unlink 10
#define __NR_osf_execve 11 /* not implemented */
#define __NR_chdir 12
#define __NR_fchdir 13
#define __NR_mknod 14
#define __NR_chmod 15
#define __NR_chown 16
#define __NR_brk 17
#define __NR_osf_getfsstat 18 /* not implemented */
#define __NR_lseek 19
#define __NR_getxpid 20
#define __NR_osf_mount 21
#define __NR_umount 22
#define __NR_setuid 23
#define __NR_getxuid 24
#define __NR_exec_with_loader 25 /* not implemented */
#define __NR_ptrace 26
#define __NR_osf_nrecvmsg 27 /* not implemented */
#define __NR_osf_nsendmsg 28 /* not implemented */
#define __NR_osf_nrecvfrom 29 /* not implemented */
#define __NR_osf_naccept 30 /* not implemented */
#define __NR_osf_ngetpeername 31 /* not implemented */
#define __NR_osf_ngetsockname 32 /* not implemented */
#define __NR_access 33
#define __NR_osf_chflags 34 /* not implemented */
#define __NR_osf_fchflags 35 /* not implemented */
#define __NR_sync 36
#define __NR_kill 37
#define __NR_osf_old_stat 38 /* not implemented */
#define __NR_setpgid 39
#define __NR_osf_old_lstat 40 /* not implemented */
#define __NR_dup 41
#define __NR_pipe 42
#define __NR_osf_set_program_attributes 43
#define __NR_osf_profil 44 /* not implemented */
#define __NR_open 45
#define __NR_osf_old_sigaction 46 /* not implemented */
#define __NR_getxgid 47
#define __NR_osf_sigprocmask 48
#define __NR_osf_getlogin 49 /* not implemented */
#define __NR_osf_setlogin 50 /* not implemented */
#define __NR_acct 51
#define __NR_sigpending 52
#define __NR_ioctl 54
#define __NR_osf_reboot 55 /* not implemented */
#define __NR_osf_revoke 56 /* not implemented */
#define __NR_symlink 57
#define __NR_readlink 58
#define __NR_execve 59
#define __NR_umask 60
#define __NR_chroot 61
#define __NR_osf_old_fstat 62 /* not implemented */
#define __NR_getpgrp 63
#define __NR_getpagesize 64
#define __NR_osf_mremap 65 /* not implemented */
#define __NR_vfork 66
#define __NR_stat 67
#define __NR_lstat 68
#define __NR_osf_sbrk 69 /* not implemented */
#define __NR_osf_sstk 70 /* not implemented */
#define __NR_mmap 71 /* OSF/1 mmap is superset of Linux */
#define __NR_osf_old_vadvise 72 /* not implemented */
#define __NR_munmap 73
#define __NR_mprotect 74
#define __NR_madvise 75
#define __NR_vhangup 76
#define __NR_osf_kmodcall 77 /* not implemented */
#define __NR_osf_mincore 78 /* not implemented */
#define __NR_getgroups 79
#define __NR_setgroups 80
#define __NR_osf_old_getpgrp 81 /* not implemented */
#define __NR_setpgrp 82 /* BSD alias for setpgid */
#define __NR_osf_setitimer 83
#define __NR_osf_old_wait 84 /* not implemented */
#define __NR_osf_table 85 /* not implemented */
#define __NR_osf_getitimer 86
#define __NR_gethostname 87
#define __NR_sethostname 88
#define __NR_getdtablesize 89
#define __NR_dup2 90
#define __NR_fstat 91
#define __NR_fcntl 92
#define __NR_osf_select 93
#define __NR_poll 94
#define __NR_fsync 95
#define __NR_setpriority 96
#define __NR_socket 97
#define __NR_connect 98
#define __NR_accept 99
#define __NR_getpriority 100
..........