系统调用第1页 - 独孤影的博客

Linux 3.2.0-33, x86_64

Note: 64-bit x86 uses syscall instead of interrupt 0x80. The result value will be in %rax

To find the implementation of a system call, grep the kernel tree for SYSCALL_DEFINE.\?(syscall,
For example, to find the read system call:

illusion:/usr/src/linux-source-3.2.0$ grep -rA3 'SYSCALL_DEFINE.\?(read,' *
fs/read_write.c:SYSCALL_DEFINE3(read, unsigned int, fd, char __user *, buf, size_t, count)
fs/read_write.c-{
fs/read_write.c-        struct file *file;
fs/read_write.c-        ssize_t ret = -EBADF;

The results show that the implementation is in fs/read_write.c and that it takes 3 arguments (thus SYSCALL_DEFINE3).

Linux Cross Reference is another good tool for finding information about system calls.

By the way, the system call numbers are different for 32-bit x86. A system call table for i386 (32-bit) can be found at http://docs.cs.up.ac.za/programming/asm/derick_tut/syscalls.htm

%rax	System call	%rdi	%rsi	%rdx	%rcx	%r8	%r9
0	sys_read	unsigned int fd	char *buf	size_t count
1	sys_write	unsigned int fd	const char *buf	size_t count
2	sys_open	const char *filename	int flags	int mode
3	sys_close	unsigned int fd
4	sys_stat	const char *filename	struct stat *statbuf
5	sys_fstat	unsigned int fd	struct stat *statbuf
6	sys_lstat	fconst char *filename	struct stat *statbuf
7	sys_poll	struct poll_fd *ufds	unsigned int nfds	long timeout_msecs
8	sys_lseek	unsigned int fd	off_t offset	unsigned int origin
9	sys_mmap	unsigned long addr	unsigned long len	unsigned long prot	unsigned long flags	unsigned long fd	unsigned long off
10	sys_mprotect	unsigned long start	size_t len	unsigned long prot
11	sys_munmap	unsigned long addr	size_t len
12	sys_brk	unsigned long brk
13	sys_rt_sigaction	int sig	const struct sigaction *act	struct sigaction *oact	size_t sigsetsize
14	sys_rt_sigprocmask	int how	sigset_t *nset	sigset_t *oset	size_t sigsetsize
15	sys_rt_sigreturn	unsigned long __unused
16	sys_ioctl	unsigned int fd	unsigned int cmd	unsigned long arg
17	sys_pread64	unsigned long fd	char *buf	size_t count	loff_t pos
18	sys_pwrite64	unsigned int fd	const char *buf	size_t count	loff_t pos
19	sys_readv	unsigned long fd	const struct iovec *vec	unsigned long vlen
20	sys_writev	unsigned long fd	const struct iovec *vec	unsigned long vlen
21	sys_access	const char *filename	int mode
22	sys_pipe	int *filedes
23	sys_select	int n	fd_set *in