Linux系统调用汇编 int 80h

2021-10-08 15:24:37

1.系统调用

在计算机中，系统调用（英语：system call），又称为系统呼叫，指运行在使用者空间的程序向操作系统内核请求需要更高权限运行的服务。系统调用提供了用户程序与操作系统之间的接口。大多数系统交互式操作需求在内核态执行。如设备IO操作或者进程间通信。

Linux的系统调用通过int 80h实现，用系统调用号来区分入口函数。操作系统实现系统调用的基本过程是：
应用程序调用库函数（API）；
API将系统调用号存入EAX，然后通过中断调用使系统进入内核态；
内核中的中断处理函数根据系统调用号，调用对应的内核函数（系统调用）；
系统调用完成相应功能，将返回值存入EAX，返回到中断处理函数；
中断处理函数返回到API中；
API将EAX返回给应用程序。

寄存器eax存放调用号，剩下的几个寄存器存放参数。

以sys_write为例说明：

函数原型：
sys_write(unsigned int fd, const char * buf, size_t count)

[section .data]
strHello db “Hello, world!”,0Ah
STRLEN equ $ - strHello
[section .text]
global _start
_start:
mov edx,STRLEN;对应参数count
mov ecx,strHello;对应参数buf
mov ebx,1;对应参数fd，fd = 1，在linux中对应于stdout，指的是显示屏
mov eax,4;系统调用号为4，sys_write
int 0x80
mov ebx,0;参数为0，exit(0)
mov eax,1;系统调用号为1，sys_exit
int 0x80

%eax	Name	Source	%ebx	%ecx	%edx	%esx	%edi
1	sys_exit	kernel/exit.c	int	-	-	-	-
2	sys_fork	arch/i386/kernel/process.c	struct pt_regs	-	-	-	-
3	sys_read	fs/read_write.c	unsigned int	char *	size_t	-	-
4	sys_write	fs/read_write.c	unsigned int	const char *	size_t	-	-
5	sys_open	fs/open.c	const char *	int	int	-	-
6	sys_close	fs/open.c	unsigned int	-	-	-	-
7	sys_waitpid	kernel/exit.c	pid_t	unsigned int *	int	-	-
8	sys_creat	fs/open.c	const char *	int	-	-	-
9	sys_link	fs/namei.c	const char *	const char *	-	-	-
10	sys_unlink	fs/namei.c	const char *	-	-	-	-
11	sys_execve	arch/i386/kernel/process.c	struct pt_regs	-	-	-	-
12	sys_chdir	fs/open.c	const char *	-	-	-	-
13	sys_time	kernel/time.c	int *	-	-	-	-
14	sys_mknod	fs/namei.c	const char *	int	dev_t	-	-
15	sys_chmod	fs/open.c	const char *	mode_t	-	-	-
16	sys_lchown	fs/open.c	const char *	uid_t	gid_t	-	-
18	sys_stat	fs/stat.c	char *	struct __old_kernel_stat *	-	-	-
19	sys_lseek	fs/read_write.c	unsigned int	off_t	unsigned int	-	-
20	sys_getpid	kernel/sched.c	-	-	-	-	-
21	sys_mount	fs/super.c	char *	char *	char *	-	-
22	sys_oldumount	fs/super.c	char *	-	-	-	-
23	sys_setuid	kernel/sys.c	uid_t	-	-	-	-
24	sys_getuid	kernel/sched.c	-	-	-	-	-
25	sys_stime	kernel/time.c	int *	-	-	-	-
26	sys_ptrace	arch/i386/kernel/ptrace.c	long	long	long	long	-
27	sys_alarm	kernel/sched.c	unsigned int	-	-	-	-
28	sys_fstat	fs/stat.c	unsigned int	struct __old_kernel_stat *	-	-	-
29	sys_pause	arch/i386/kernel/sys_i386.c	-	-	-	-	-
30	sys_utime	fs/open.c	char *	struct utimbuf *	-	-	-
33	sys_access	fs/open.c	const char *	int	-	-	-
34	sys_nice	kernel/sched.c	int	-	-	-	-
36	sys_sync	fs/buffer.c	-	-	-	-	-
37	sys_kill	kernel/signal.c	int	int	-	-	-
38	sys_rename	fs/namei.c	const char *	const char *	-	-	-
39	sys_mkdir	fs/namei.c	const char *	int	-	-	-
40	sys_rmdir	fs/namei.c	const char *	-	-	-	-
41	sys_dup	fs/fcntl.c	unsigned int	-	-	-	-
42	sys_pipe	arch/i386/kernel/sys_i386.c	unsigned long *	-	-	-	-
43	sys_times	kernel/sys.c	struct tms *	-	-	-	-
45	sys_brk	mm/mmap.c	unsigned long	-	-	-	-
46	sys_setgid	kernel/sys.c	gid_t	-	-	-	-
47	sys_getgid	kernel/sched.c	-	-	-	-	-
48	sys_signal	kernel/signal.c	int	__sighandler_t	-	-	-
49	sys_geteuid	kernel/sched.c	-	-	-	-	-
50	sys_getegid	kernel/sched.c	-	-	-	-	-
51	sys_acct	kernel/acct.c	const char *	-	-	-	-
52	sys_umount	fs/super.c	char *	int	-	-	-
54	sys_ioctl	fs/ioctl.c	unsigned int	unsigned int	unsigned long	-	-
55	sys_fcntl	fs/fcntl.c	unsigned int	unsigned int	unsigned long	-	-
57	sys_setpgid	kernel/sys.c	pid_t	pid_t	-	-	-
59	sys_olduname	arch/i386/kernel/sys_i386.c	struct oldold_utsname *	-	-	-	-
60	sys_umask	kernel/sys.c	int	-	-	-	-
61	sys_chroot	fs/open.c	const char *	-	-	-	-
62	sys_ustat	fs/super.c	dev_t	struct ustat *	-	-	-
63	sys_dup2	fs/fcntl.c	unsigned int	unsigned int	-	-	-
64	sys_getppid	kernel/sched.c	-	-	-	-	-
65	sys_getpgrp	kernel/sys.c	-	-	-	-	-
66	sys_setsid	kernel/sys.c	-	-	-	-	-
67	sys_sigaction	arch/i386/kernel/signal.c	int	const struct old_sigaction *	struct old_sigaction *	-	-
68	sys_sgetmask	kernel/signal.c	-	-	-	-	-
69	sys_ssetmask	kernel/signal.c	int	-	-	-	-
70	sys_setreuid	kernel/sys.c	uid_t	uid_t	-	-	-
71	sys_setregid	kernel/sys.c	gid_t	gid_t	-	-	-
72	sys_sigsuspend	arch/i386/kernel/signal.c	int	int	old_sigset_t	-	-
73	sys_sigpending	kernel/signal.c	old_sigset_t *	-	-	-	-
74	sys_sethostname	kernel/sys.c	char *	int	-	-	-
75	sys_setrlimit	kernel/sys.c	unsigned int	struct rlimit *	-	-	-
76	sys_getrlimit	kernel/sys.c	unsigned int	struct rlimit *	-	-	-
77	sys_getrusage	kernel/sys.c	int	struct rusage *	-	-	-
78	sys_gettimeofday	kernel/time.c	struct timeval *	struct timezone *	-	-	-
79	sys_settimeofday	kernel/time.c	struct timeval *	struct timezone *	-	-	-
80	sys_getgroups	kernel/sys.c	int	gid_t *	-	-	-
81	sys_setgroups	kernel/sys.c	int	gid_t *	-	-	-
82	old_select	arch/i386/kernel/sys_i386.c	struct sel_arg_struct *	-	-	-	-
83	sys_symlink	fs/namei.c	const char *	const char *	-	-	-
84	sys_lstat	fs/stat.c	char *	struct __old_kernel_stat *	-	-	-
85	sys_readlink	fs/stat.c	const char *	char *	int	-	-
86	sys_uselib	fs/exec.c	const char *	-	-	-	-
87	sys_swapon	mm/swapfile.c	const char *	int	-	-	-
88	sys_reboot	kernel/sys.c	int	int	int	void *	-
89	old_readdir	fs/readdir.c	unsigned int	void *	unsigned int	-	-
90	old_mmap	arch/i386/kernel/sys_i386.c	struct mmap_arg_struct *	-	-	-	-
91	sys_munmap	mm/mmap.c	unsigned long	size_t	-	-	-
92	sys_truncate	fs/open.c	const char *	unsigned long	-	-	-
93	sys_ftruncate	fs/open.c	unsigned int	unsigned long	-	-	-
94	sys_fchmod	fs/open.c	unsigned int	mode_t	-	-	-
95	sys_fchown	fs/open.c	unsigned int	uid_t	gid_t	-	-
96	sys_getpriority	kernel/sys.c	int	int	-	-	-
97	sys_setpriority	kernel/sys.c	int	int	int	-	-
99	sys_statfs	fs/open.c	const char *	struct statfs *	-	-	-
100	sys_fstatfs	fs/open.c	unsigned int	struct statfs *	-	-	-
101	sys_ioperm	arch/i386/kernel/ioport.c	unsigned long	unsigned long	int	-	-
102	sys_socketcall	net/socket.c	int	unsigned long *	-	-	-
103	sys_syslog	kernel/printk.c	int	char *	int	-	-
104	sys_setitimer	kernel/itimer.c	int	struct itimerval *	struct itimerval *	-	-
105	sys_getitimer	kernel/itimer.c	int	struct itimerval *	-	-	-
106	sys_newstat	fs/stat.c	char *	struct stat *	-	-	-
107	sys_newlstat	fs/stat.c	char *	struct stat *	-	-	-
108	sys_newfstat	fs/stat.c	unsigned int	struct stat *	-	-	-
109	sys_uname	arch/i386/kernel/sys_i386.c	struct old_utsname *	-	-	-	-
110	sys_iopl	arch/i386/kernel/ioport.c	unsigned long	-	-	-	-
111	sys_vhangup	fs/open.c	-	-	-	-	-
112	sys_idle	arch/i386/kernel/process.c	-	-	-	-	-
113	sys_vm86old	arch/i386/kernel/vm86.c	unsigned long	struct vm86plus_struct *	-	-	-
114	sys_wait4	kernel/exit.c	pid_t	unsigned long *	int options	struct rusage *	-
115	sys_swapoff	mm/swapfile.c	const char *	-	-	-	-
116	sys_sysinfo	kernel/info.c	struct sysinfo *	-	-	-	-
117	sys_ipc (*Note)	arch/i386/kernel/sys_i386.c	uint	int	int	int	void *
118	sys_fsync	fs/buffer.c	unsigned int	-	-	-	-
119	sys_sigreturn	arch/i386/kernel/signal.c	unsigned long	-	-	-	-
120	sys_clone	arch/i386/kernel/process.c	struct pt_regs	-	-	-	-
121	sys_setdomainname	kernel/sys.c	char *	int	-	-	-
122	sys_newuname	kernel/sys.c	struct new_utsname *	-	-	-	-
123	sys_modify_ldt	arch/i386/kernel/ldt.c	int	void *	unsigned long	-	-
124	sys_adjtimex	kernel/time.c	struct timex *	-	-	-	-
125	sys_mprotect	mm/mprotect.c	unsigned long	size_t	unsigned long	-	-
126	sys_sigprocmask	kernel/signal.c	int	old_sigset_t *	old_sigset_t *	-	-
127	sys_create_module	kernel/module.c	const char *	size_t	-	-	-
128	sys_init_module	kernel/module.c	const char *	struct module *	-	-	-
129	sys_delete_module	kernel/module.c	const char *	-	-	-	-
130	sys_get_kernel_syms	kernel/module.c	struct kernel_sym *	-	-	-	-
131	sys_quotactl	fs/dquot.c	int	const char *	int	caddr_t	-
132	sys_getpgid	kernel/sys.c	pid_t	-	-	-	-
133	sys_fchdir	fs/open.c	unsigned int	-	-	-	-
134	sys_bdflush	fs/buffer.c	int	long	-	-	-
135	sys_sysfs	fs/super.c	int	unsigned long	unsigned long	-	-
136	sys_personality	kernel/exec_domain.c	unsigned long	-	-	-	-
138	sys_setfsuid	kernel/sys.c	uid_t	-	-	-	-
139	sys_setfsgid	kernel/sys.c	gid_t	-	-	-	-
140	sys_llseek	fs/read_write.c	unsigned int	unsigned long	unsigned long	loff_t *	unsigned int
141	sys_getdents	fs/readdir.c	unsigned int	void *	unsigned int	-	-
142	sys_select	fs/select.c	int	fd_set *	fd_set *	fd_set *	struct timeval *
143	sys_flock	fs/locks.c	unsigned int	unsigned int	-	-	-
144	sys_msync	mm/filemap.c	unsigned long	size_t	int	-	-
145	sys_readv	fs/read_write.c	unsigned long	const struct iovec *	unsigned long	-	-
146	sys_writev	fs/read_write.c	unsigned long	const struct iovec *	unsigned long	-	-
147	sys_getsid	kernel/sys.c	pid_t	-	-	-	-
148	sys_fdatasync	fs/buffer.c	unsigned int	-	-	-	-
149	sys_sysctl	kernel/sysctl.c	struct __sysctl_args *	-	-	-	-
150	sys_mlock	mm/mlock.c	unsigned long	size_t	-	-	-
151	sys_munlock	mm/mlock.c	unsigned long	size_t	-	-	-
152	sys_mlockall	mm/mlock.c	int	-	-	-	-
153	sys_munlockall	mm/mlock.c	-	-	-	-	-
154	sys_sched_setparam	kernel/sched.c	pid_t	struct sched_param *	-	-	-
155	sys_sched_getparam	kernel/sched.c	pid_t	struct sched_param *	-	-	-
156	sys_sched_setscheduler	kernel/sched.c	pid_t	int	struct sched_param *	-	-
157	sys_sched_getscheduler	kernel/sched.c	pid_t	-	-	-	-
158	sys_sched_yield	kernel/sched.c	-	-	-	-	-
159	sys_sched_get_priority_max	kernel/sched.c	int	-	-	-	-
160	sys_sched_get_priority_min	kernel/sched.c	int	-	-	-	-
161	sys_sched_rr_get_interval	kernel/sched.c	pid_t	struct timespec *	-	-	-
162	sys_nanosleep	kernel/sched.c	struct timespec *	struct timespec *	-	-	-
163	sys_mremap	mm/mremap.c	unsigned long	unsigned long	unsigned long	unsigned long	-
164	sys_setresuid	kernel/sys.c	uid_t	uid_t	uid_t	-	-
165	sys_getresuid	kernel/sys.c	uid_t *	uid_t *	uid_t *	-	-
166	sys_vm86	arch/i386/kernel/vm86.c	struct vm86_struct *	-	-	-	-
167	sys_query_module	kernel/module.c	const char *	int	char *	size_t	size_t *
168	sys_poll	fs/select.c	struct pollfd *	unsigned int	long	-	-
169	sys_nfsservctl	fs/filesystems.c	int	void *	void *	-	-
170	sys_setresgid	kernel/sys.c	gid_t	gid_t	gid_t	-	-
171	sys_getresgid	kernel/sys.c	gid_t *	gid_t *	gid_t *	-	-
172	sys_prctl	kernel/sys.c	int	unsigned long	unsigned long	unsigned long	unsigned long
173	sys_rt_sigreturn	arch/i386/kernel/signal.c	unsigned long	-	-	-	-
174	sys_rt_sigaction	kernel/signal.c	int	const struct sigaction *	struct sigaction *	size_t	-
175	sys_rt_sigprocmask	kernel/signal.c	int	sigset_t *	sigset_t *	size_t	-
176	sys_rt_sigpending	kernel/signal.c	sigset_t *	size_t	-	-	-
177	sys_rt_sigtimedwait	kernel/signal.c	const sigset_t *	siginfo_t *	const struct timespec *	size_t	-
178	sys_rt_sigqueueinfo	kernel/signal.c	int	int	siginfo_t *	-	-
179	sys_rt_sigsuspend	arch/i386/kernel/signal.c	sigset_t *	size_t	-	-	-
180	sys_pread	fs/read_write.c	unsigned int	char *	size_t	loff_t	-
181	sys_pwrite	fs/read_write.c	unsigned int	const char *	size_t	loff_t	-
182	sys_chown	fs/open.c	const char *	uid_t	gid_t	-	-
183	sys_getcwd	fs/dcache.c	char *	unsigned long	-	-	-
184	sys_capget	kernel/capability.c	cap_user_header_t	cap_user_data_t	-	-	-
185	sys_capset	kernel/capability.c	cap_user_header_t	const cap_user_data_t	-	-	-
186	sys_sigaltstack	arch/i386/kernel/signal.c	const stack_t *	stack_t *	-	-	-
187	sys_sendfile	mm/filemap.c	int	int	off_t *	size_t	-
190	sys_vfork	arch/i386/kernel/process.c	struct pt_regs	-	-	-	-

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