linux系统调用
一.声明系统调用的相关宏
1.SYSCALL_DEFINE1~6
#define SYSCALL_DEFINE1(name, ...) SYSCALL_DEFINEx(1, _##name, __VA_ARGS__) #define SYSCALL_DEFINE2(name, ...) SYSCALL_DEFINEx(2, _##name, __VA_ARGS__) #define SYSCALL_DEFINE3(name, ...) SYSCALL_DEFINEx(3, _##name, __VA_ARGS__) #define SYSCALL_DEFINE4(name, ...) SYSCALL_DEFINEx(4, _##name, __VA_ARGS__) #define SYSCALL_DEFINE5(name, ...) SYSCALL_DEFINEx(5, _##name, __VA_ARGS__) #define SYSCALL_DEFINE6(name, ...) SYSCALL_DEFINEx(6, _##name, __VA_ARGS__)
2.SYSCALL_DEFINEx
#define SYSCALL_DEFINEx(x, sname, ...) \ __SYSCALL_DEFINEx(x, sname, __VA_ARGS__)
3.__SYSCALL_DEFINEx
#define __SYSCALL_DEFINEx(x, name, ...) \
asmlinkage long sys##name(__SC_DECL##x(__VA_ARGS__)); \
static inline long SYSC##name(__SC_DECL##x(__VA_ARGS__)); \
asmlinkage long SyS##name(__SC_LONG##x(__VA_ARGS__)) \
{ \
__SC_TEST##x(__VA_ARGS__); \
return (long) SYSC##name(__SC_CAST##x(__VA_ARGS__)); \
} \
SYSCALL_ALIAS(sys##name, SyS##name); \
static inline long SYSC##name(__SC_DECL##x(__VA_ARGS__))
4.__SC_开头的宏
#define __SC_DECL1(t1, a1) t1 a1 #define __SC_DECL2(t2, a2, ...) t2 a2, __SC_DECL1(__VA_ARGS__) #define __SC_DECL3(t3, a3, ...) t3 a3, __SC_DECL2(__VA_ARGS__) #define __SC_DECL4(t4, a4, ...) t4 a4, __SC_DECL3(__VA_ARGS__) #define __SC_DECL5(t5, a5, ...) t5 a5, __SC_DECL4(__VA_ARGS__) #define __SC_DECL6(t6, a6, ...) t6 a6, __SC_DECL5(__VA_ARGS__) #define __SC_LONG1(t1, a1) long a1 #define __SC_LONG2(t2, a2, ...) long a2, __SC_LONG1(__VA_ARGS__) #define __SC_LONG3(t3, a3, ...) long a3, __SC_LONG2(__VA_ARGS__) #define __SC_LONG4(t4, a4, ...) long a4, __SC_LONG3(__VA_ARGS__) #define __SC_LONG5(t5, a5, ...) long a5, __SC_LONG4(__VA_ARGS__) #define __SC_LONG6(t6, a6, ...) long a6, __SC_LONG5(__VA_ARGS__) #define __SC_CAST1(t1, a1) (t1) a1 #define __SC_CAST2(t2, a2, ...) (t2) a2, __SC_CAST1(__VA_ARGS__) #define __SC_CAST3(t3, a3, ...) (t3) a3, __SC_CAST2(__VA_ARGS__) #define __SC_CAST4(t4, a4, ...) (t4) a4, __SC_CAST3(__VA_ARGS__) #define __SC_CAST5(t5, a5, ...) (t5) a5, __SC_CAST4(__VA_ARGS__) #define __SC_CAST6(t6, a6, ...) (t6) a6, __SC_CAST5(__VA_ARGS__) #define __SC_TEST(type) BUILD_BUG_ON(sizeof(type) > sizeof(long)) #define __SC_TEST1(t1, a1) __SC_TEST(t1) #define __SC_TEST2(t2, a2, ...) __SC_TEST(t2); __SC_TEST1(__VA_ARGS__) #define __SC_TEST3(t3, a3, ...) __SC_TEST(t3); __SC_TEST2(__VA_ARGS__) #define __SC_TEST4(t4, a4, ...) __SC_TEST(t4); __SC_TEST3(__VA_ARGS__) #define __SC_TEST5(t5, a5, ...) __SC_TEST(t5); __SC_TEST4(__VA_ARGS__) #define __SC_TEST6(t6, a6, ...) __SC_TEST(t6); __SC_TEST5(__VA_ARGS__)
5.针对SYSCALL_DEFINE1(close, unsigned int, fd)来分析一下
SYSCALL_DEFINE1(close, unsigned int, fd)根据#define SYSCALL_DEFINE1(name, ...) SYSCALL_DEFINEx(1, _##name, __VA_ARGS__)
化简SYSCALL_DEFINEx(1, _close, __VA_ARGS__) 【 ##是连接符的意思】,根据SYSCALL_DEFINEx的定义
化简__SYSCALL_DEFINEx(1, _close, __VA_ARGS__) 根据__SYSCALL_DEFINEx的定义
化简
#define __SYSCALL_DEFINEx(1, _close, ...) \
asmlinkage long sys_close(__SC_DECL1(__VA_ARGS__)); \
static inline long SYSC_close(__SC_DECL1(__VA_ARGS__)); \
asmlinkage long SyS_close(__SC_LONG1(__VA_ARGS__)) \
{ \
__SC_TEST1(__VA_ARGS__); \
return (long) SYSC_close(__SC_CAST1(__VA_ARGS__)); \
} \
SYSCALL_ALIAS(sys_close, SyS_close); \
static inline long SYSC_close(__SC_DECL1(__VA_ARGS__))
这里__VA_ARGS__是可变参数宏,可以认为等于unsigned int, fd
根据__SC_宏化简
#define __SYSCALL_DEFINEx(1, _close, ...) \
asmlinkage long sys_close(unsigned int fd); \
static inline long SYSC_close(unsigned int fd); \
asmlinkage long SyS_close(long fd)) \
{ \
BUILD_BUG_ON(sizeof(unsigned int) > sizeof(long)) \
return (long) SYSC_close((unsigned int)fd); \
} \
SYSCALL_ALIAS(sys_close, SyS_close); \
static inline long SYSC_close(unsigned int fd)
声明了sys_close函数
声明了SYSC_close内联函数
定义了SyS_close函数,函数体调用SYSC_close函数,并返回其返回值
SYSCALL_ALIAS宏
#define SYSCALL_ALIAS(alias, name) \
asm ("\t.globl " #alias "\n\t.set " #alias ", " #name)
插入汇编代码 让执行sys_close等同于执行SYS_close
asm ("\t.globl " #sys_close "\n\t.set " #sys_close ", " #SyS_close)
【#是预处理的意思】
BUILD_BUG_ON宏是个错误判断检测的功能
最后一句是SYSC_close的函数定义
所以在SYSCALL_DEFINE1宏定义后面紧跟的是{}包围起来的函数体
6.根据5的解析可推断出
SYSCALL_DEFINE1的'1'代表的是sys_close的参数个数为1
同理SYSCALL_DEFINE?的'/'代表的是sys_name的参数为'?'个
7.系统调用函数的定义用SYSCALL_DEFINE宏修饰
系统调用函数的外部声明在include/linux/Syscalls.h头文件中
二.应用程序调用系统调用
应用程序调用系统调用是通过汇编的swi指令+val
swi处理的函数定义在/arch/arm/kernel/entry-commmon.S中(针对arm)
ENTRY(vector_swi)
sub sp, sp, #S_FRAME_SIZE
stmia sp, {r0 - r12} @ Calling r0 - r12
ARM( add r8, sp, #S_PC )
ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr
THUMB( mov r8, sp )
THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr
mrs r8, spsr @ called from non-FIQ mode, so ok.
str lr, [sp, #S_PC] @ Save calling PC
str r8, [sp, #S_PSR] @ Save CPSR
str r0, [sp, #S_OLD_R0] @ Save OLD_R0
zero_fp
/*
* Get the system call number.获取系统调用号
*/
#if defined(CONFIG_OABI_COMPAT)
/*
* If we have CONFIG_OABI_COMPAT then we need to look at the swi
* value to determine if it is an EABI or an old ABI call.
*/
#ifdef CONFIG_ARM_THUMB
tst r8, #PSR_T_BIT
movne r10, #0 @ no thumb OABI emulation
ldreq r10, [lr, #-4] @ get SWI instruction
#else
ldr r10, [lr, #-4] @ get SWI instruction
A710( and ip, r10, #0x0f000000 @ check for SWI )
A710( teq ip, #0x0f000000 )
A710( bne .Larm710bug )
#endif
#ifdef CONFIG_CPU_ENDIAN_BE8
rev r10, r10 @ little endian instruction
#endif
#elif defined(CONFIG_AEABI)
/*
* Pure EABI user space always put syscall number into scno (r7).
*/
A710( ldr ip, [lr, #-4] @ get SWI instruction )
A710( and ip, ip, #0x0f000000 @ check for SWI )
A710( teq ip, #0x0f000000 )
A710( bne .Larm710bug )
#elif defined(CONFIG_ARM_THUMB)
/* Legacy ABI only, possibly thumb mode. */
tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs
addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in
ldreq scno, [lr, #-4]
#else
/* Legacy ABI only. */
ldr scno, [lr, #-4] @ get SWI instruction
A710( and ip, scno, #0x0f000000 @ check for SWI )
A710( teq ip, #0x0f000000 )
A710( bne .Larm710bug )
#endif
#ifdef CONFIG_ALIGNMENT_TRAP
ldr ip, __cr_alignment
ldr ip, [ip]
mcr p15, 0, ip, c1, c0 @ update control register
#endif
enable_irq
get_thread_info tsk
adr tbl, sys_call_table @ load syscall table pointer 加载系统调用表指针
#if defined(CONFIG_OABI_COMPAT)
/*
* If the swi argument is zero, this is an EABI call and we do nothing.
*
* If this is an old ABI call, get the syscall number into scno and
* get the old ABI syscall table address.
*/
bics r10, r10, #0xff000000
eorne scno, r10, #__NR_OABI_SYSCALL_BASE
ldrne tbl, =sys_oabi_call_table
#elif !defined(CONFIG_AEABI)
bic scno, scno, #0xff000000 @ mask off SWI op-code SWI操作码掩码 获取操作码到scno
eor scno, scno, #__NR_SYSCALL_BASE @ check OS number
#endif
ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing
stmdb sp!, {r4, r5} @ push fifth and sixth args
#ifdef CONFIG_SECCOMP
tst r10, #_TIF_SECCOMP
beq 1f
mov r0, scno
bl __secure_computing
add r0, sp, #S_R0 + S_OFF @ pointer to regs
ldmia r0, {r0 - r3} @ have to reload r0 - r3
1:
#endif
tst r10, #_TIF_SYSCALL_TRACE @ are we tracing syscalls? 我们用了trace命令调试系统调用
bne __sys_trace @跳去__sys_trace 这是trace命令能分析系统调用关系的原因
cmp scno, #NR_syscalls @ check upper syscall limit
adr lr, BSYM(ret_fast_syscall) @ return address
ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine 调用sys_xxx函数
@ 系统调用表的第scno(操作码)项的值给到PC
add r1, sp, #S_OFF
2: mov why, #0 @ no longer a real syscall
cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
eor r0, scno, #__NR_SYSCALL_BASE @ put OS number back
bcs arm_syscall
b sys_ni_syscall @ not private func
ENDPROC(vector_swi)
sys_call_table表在entry-common.S中定义
.type sys_call_table, #object ENTRY(sys_call_table) #include "calls.S"
该表包含了calls.S文件
/* * linux/arch/arm/kernel/calls.S * * Copyright (C) 1995-2005 Russell King * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * This file is included thrice in entry-common.S */ /* 0 */ CALL(sys_restart_syscall) CALL(sys_exit) CALL(sys_fork_wrapper) CALL(sys_read) CALL(sys_write) /* 5 */ CALL(sys_open) CALL(sys_close) CALL(sys_ni_syscall) /* was sys_waitpid */ CALL(sys_creat) CALL(sys_link) /* 10 */ CALL(sys_unlink) CALL(sys_execve_wrapper) CALL(sys_chdir) CALL(OBSOLETE(sys_time)) /* used by libc4 */ CALL(sys_mknod) /* 15 */ CALL(sys_chmod) CALL(sys_lchown16) CALL(sys_ni_syscall) /* was sys_break */ CALL(sys_ni_syscall) /* was sys_stat */ CALL(sys_lseek) /* 20 */ CALL(sys_getpid) CALL(sys_mount) CALL(OBSOLETE(sys_oldumount)) /* used by libc4 */ CALL(sys_setuid16) CALL(sys_getuid16) /* 25 */ CALL(OBSOLETE(sys_stime)) CALL(sys_ptrace) CALL(OBSOLETE(sys_alarm)) /* used by libc4 */ CALL(sys_ni_syscall) /* was sys_fstat */ CALL(sys_pause) /* 30 */ CALL(OBSOLETE(sys_utime)) /* used by libc4 */ CALL(sys_ni_syscall) /* was sys_stty */ CALL(sys_ni_syscall) /* was sys_getty */ CALL(sys_access) CALL(sys_nice) /* 35 */ CALL(sys_ni_syscall) /* was sys_ftime */ CALL(sys_sync) CALL(sys_kill) CALL(sys_rename) CALL(sys_mkdir) /* 40 */ CALL(sys_rmdir) CALL(sys_dup) CALL(sys_pipe) CALL(sys_times) CALL(sys_ni_syscall) /* was sys_prof */ /* 45 */ CALL(sys_brk) CALL(sys_setgid16) CALL(sys_getgid16) CALL(sys_ni_syscall) /* was sys_signal */ CALL(sys_geteuid16) /* 50 */ CALL(sys_getegid16) CALL(sys_acct) CALL(sys_umount) CALL(sys_ni_syscall) /* was sys_lock */ CALL(sys_ioctl) /* 55 */ CALL(sys_fcntl) CALL(sys_ni_syscall) /* was sys_mpx */ CALL(sys_setpgid) CALL(sys_ni_syscall) /* was sys_ulimit */ CALL(sys_ni_syscall) /* was sys_olduname */ /* 60 */ CALL(sys_umask) CALL(sys_chroot) CALL(sys_ustat) CALL(sys_dup2) CALL(sys_getppid) /* 65 */ CALL(sys_getpgrp) CALL(sys_setsid) CALL(sys_sigaction) CALL(sys_ni_syscall) /* was sys_sgetmask */ CALL(sys_ni_syscall) /* was sys_ssetmask */ /* 70 */ CALL(sys_setreuid16) CALL(sys_setregid16) CALL(sys_sigsuspend) CALL(sys_sigpending) CALL(sys_sethostname) /* 75 */ CALL(sys_setrlimit) CALL(OBSOLETE(sys_old_getrlimit)) /* used by libc4 */ CALL(sys_getrusage) CALL(sys_gettimeofday) CALL(sys_settimeofday) /* 80 */ CALL(sys_getgroups16) CALL(sys_setgroups16) CALL(OBSOLETE(sys_old_select)) /* used by libc4 */ CALL(sys_symlink) CALL(sys_ni_syscall) /* was sys_lstat */ /* 85 */ CALL(sys_readlink) CALL(sys_uselib) CALL(sys_swapon) CALL(sys_reboot) CALL(OBSOLETE(sys_old_readdir)) /* used by libc4 */ /* 90 */ CALL(OBSOLETE(sys_old_mmap)) /* used by libc4 */ CALL(sys_munmap) CALL(sys_truncate) CALL(sys_ftruncate) CALL(sys_fchmod) /* 95 */ CALL(sys_fchown16) CALL(sys_getpriority) CALL(sys_setpriority) CALL(sys_ni_syscall) /* was sys_profil */ CALL(sys_statfs) /* 100 */ CALL(sys_fstatfs) CALL(sys_ni_syscall) /* sys_ioperm */ CALL(OBSOLETE(ABI(sys_socketcall, sys_oabi_socketcall))) CALL(sys_syslog) CALL(sys_setitimer) /* 105 */ CALL(sys_getitimer) CALL(sys_newstat) CALL(sys_newlstat) CALL(sys_newfstat) CALL(sys_ni_syscall) /* was sys_uname */ /* 110 */ CALL(sys_ni_syscall) /* was sys_iopl */ CALL(sys_vhangup) CALL(sys_ni_syscall) CALL(OBSOLETE(sys_syscall)) /* call a syscall */ CALL(sys_wait4) /* 115 */ CALL(sys_swapoff) CALL(sys_sysinfo) CALL(OBSOLETE(ABI(sys_ipc, sys_oabi_ipc))) CALL(sys_fsync) CALL(sys_sigreturn_wrapper) /* 120 */ CALL(sys_clone_wrapper) CALL(sys_setdomainname) CALL(sys_newuname) CALL(sys_ni_syscall) /* modify_ldt */ CALL(sys_adjtimex) /* 125 */ CALL(sys_mprotect) CALL(sys_sigprocmask) CALL(sys_ni_syscall) /* was sys_create_module */ CALL(sys_init_module) CALL(sys_delete_module) /* 130 */ CALL(sys_ni_syscall) /* was sys_get_kernel_syms */ CALL(sys_quotactl) CALL(sys_getpgid) CALL(sys_fchdir) CALL(sys_bdflush) /* 135 */ CALL(sys_sysfs) CALL(sys_personality) CALL(sys_ni_syscall) /* reserved for afs_syscall */ CALL(sys_setfsuid16) CALL(sys_setfsgid16) /* 140 */ CALL(sys_llseek) CALL(sys_getdents) CALL(sys_select) CALL(sys_flock) CALL(sys_msync) /* 145 */ CALL(sys_readv) CALL(sys_writev) CALL(sys_getsid) CALL(sys_fdatasync) CALL(sys_sysctl) /* 150 */ CALL(sys_mlock) CALL(sys_munlock) CALL(sys_mlockall) CALL(sys_munlockall) CALL(sys_sched_setparam) /* 155 */ CALL(sys_sched_getparam) CALL(sys_sched_setscheduler) CALL(sys_sched_getscheduler) CALL(sys_sched_yield) CALL(sys_sched_get_priority_max) /* 160 */ CALL(sys_sched_get_priority_min) CALL(sys_sched_rr_get_interval) CALL(sys_nanosleep) CALL(sys_mremap) CALL(sys_setresuid16) /* 165 */ CALL(sys_getresuid16) CALL(sys_ni_syscall) /* vm86 */ CALL(sys_ni_syscall) /* was sys_query_module */ CALL(sys_poll) CALL(sys_nfsservctl) /* 170 */ CALL(sys_setresgid16) CALL(sys_getresgid16) CALL(sys_prctl) CALL(sys_rt_sigreturn_wrapper) CALL(sys_rt_sigaction) /* 175 */ CALL(sys_rt_sigprocmask) CALL(sys_rt_sigpending) CALL(sys_rt_sigtimedwait) CALL(sys_rt_sigqueueinfo) CALL(sys_rt_sigsuspend) /* 180 */ CALL(ABI(sys_pread64, sys_oabi_pread64)) CALL(ABI(sys_pwrite64, sys_oabi_pwrite64)) CALL(sys_chown16) CALL(sys_getcwd) CALL(sys_capget) /* 185 */ CALL(sys_capset) CALL(sys_sigaltstack_wrapper) CALL(sys_sendfile) CALL(sys_ni_syscall) /* getpmsg */ CALL(sys_ni_syscall) /* putpmsg */ /* 190 */ CALL(sys_vfork_wrapper) CALL(sys_getrlimit) CALL(sys_mmap2) CALL(ABI(sys_truncate64, sys_oabi_truncate64)) CALL(ABI(sys_ftruncate64, sys_oabi_ftruncate64)) /* 195 */ CALL(ABI(sys_stat64, sys_oabi_stat64)) CALL(ABI(sys_lstat64, sys_oabi_lstat64)) CALL(ABI(sys_fstat64, sys_oabi_fstat64)) CALL(sys_lchown) CALL(sys_getuid) /* 200 */ CALL(sys_getgid) CALL(sys_geteuid) CALL(sys_getegid) CALL(sys_setreuid) CALL(sys_setregid) /* 205 */ CALL(sys_getgroups) CALL(sys_setgroups) CALL(sys_fchown) CALL(sys_setresuid) CALL(sys_getresuid) /* 210 */ CALL(sys_setresgid) CALL(sys_getresgid) CALL(sys_chown) CALL(sys_setuid) CALL(sys_setgid) /* 215 */ CALL(sys_setfsuid) CALL(sys_setfsgid) CALL(sys_getdents64) CALL(sys_pivot_root) CALL(sys_mincore) /* 220 */ CALL(sys_madvise) CALL(ABI(sys_fcntl64, sys_oabi_fcntl64)) CALL(sys_ni_syscall) /* TUX */ CALL(sys_ni_syscall) CALL(sys_gettid) /* 225 */ CALL(ABI(sys_readahead, sys_oabi_readahead)) CALL(sys_setxattr) CALL(sys_lsetxattr) CALL(sys_fsetxattr) CALL(sys_getxattr) /* 230 */ CALL(sys_lgetxattr) CALL(sys_fgetxattr) CALL(sys_listxattr) CALL(sys_llistxattr) CALL(sys_flistxattr) /* 235 */ CALL(sys_removexattr) CALL(sys_lremovexattr) CALL(sys_fremovexattr) CALL(sys_tkill) CALL(sys_sendfile64) /* 240 */ CALL(sys_futex) CALL(sys_sched_setaffinity) CALL(sys_sched_getaffinity) CALL(sys_io_setup) CALL(sys_io_destroy) /* 245 */ CALL(sys_io_getevents) CALL(sys_io_submit) CALL(sys_io_cancel) CALL(sys_exit_group) CALL(sys_lookup_dcookie) /* 250 */ CALL(sys_epoll_create) CALL(ABI(sys_epoll_ctl, sys_oabi_epoll_ctl)) CALL(ABI(sys_epoll_wait, sys_oabi_epoll_wait)) CALL(sys_remap_file_pages) CALL(sys_ni_syscall) /* sys_set_thread_area */ /* 255 */ CALL(sys_ni_syscall) /* sys_get_thread_area */ CALL(sys_set_tid_address) CALL(sys_timer_create) CALL(sys_timer_settime) CALL(sys_timer_gettime) /* 260 */ CALL(sys_timer_getoverrun) CALL(sys_timer_delete) CALL(sys_clock_settime) CALL(sys_clock_gettime) CALL(sys_clock_getres) /* 265 */ CALL(sys_clock_nanosleep) CALL(sys_statfs64_wrapper) CALL(sys_fstatfs64_wrapper) CALL(sys_tgkill) CALL(sys_utimes) /* 270 */ CALL(sys_arm_fadvise64_64) CALL(sys_pciconfig_iobase) CALL(sys_pciconfig_read) CALL(sys_pciconfig_write) CALL(sys_mq_open) /* 275 */ CALL(sys_mq_unlink) CALL(sys_mq_timedsend) CALL(sys_mq_timedreceive) CALL(sys_mq_notify) CALL(sys_mq_getsetattr) /* 280 */ CALL(sys_waitid) CALL(sys_socket) CALL(ABI(sys_bind, sys_oabi_bind)) CALL(ABI(sys_connect, sys_oabi_connect)) CALL(sys_listen) /* 285 */ CALL(sys_accept) CALL(sys_getsockname) CALL(sys_getpeername) CALL(sys_socketpair) CALL(sys_send) /* 290 */ CALL(ABI(sys_sendto, sys_oabi_sendto)) CALL(sys_recv) CALL(sys_recvfrom) CALL(sys_shutdown) CALL(sys_setsockopt) /* 295 */ CALL(sys_getsockopt) CALL(ABI(sys_sendmsg, sys_oabi_sendmsg)) CALL(sys_recvmsg) CALL(ABI(sys_semop, sys_oabi_semop)) CALL(sys_semget) /* 300 */ CALL(sys_semctl) CALL(sys_msgsnd) CALL(sys_msgrcv) CALL(sys_msgget) CALL(sys_msgctl) /* 305 */ CALL(sys_shmat) CALL(sys_shmdt) CALL(sys_shmget) CALL(sys_shmctl) CALL(sys_add_key) /* 310 */ CALL(sys_request_key) CALL(sys_keyctl) CALL(ABI(sys_semtimedop, sys_oabi_semtimedop)) /* vserver */ CALL(sys_ni_syscall) CALL(sys_ioprio_set) /* 315 */ CALL(sys_ioprio_get) CALL(sys_inotify_init) CALL(sys_inotify_add_watch) CALL(sys_inotify_rm_watch) CALL(sys_mbind) /* 320 */ CALL(sys_get_mempolicy) CALL(sys_set_mempolicy) CALL(sys_openat) CALL(sys_mkdirat) CALL(sys_mknodat) /* 325 */ CALL(sys_fchownat) CALL(sys_futimesat) CALL(ABI(sys_fstatat64, sys_oabi_fstatat64)) CALL(sys_unlinkat) CALL(sys_renameat) /* 330 */ CALL(sys_linkat) CALL(sys_symlinkat) CALL(sys_readlinkat) CALL(sys_fchmodat) CALL(sys_faccessat) /* 335 */ CALL(sys_pselect6) CALL(sys_ppoll) CALL(sys_unshare) CALL(sys_set_robust_list) CALL(sys_get_robust_list) /* 340 */ CALL(sys_splice) CALL(sys_sync_file_range2) CALL(sys_tee) CALL(sys_vmsplice) CALL(sys_move_pages) /* 345 */ CALL(sys_getcpu) CALL(sys_epoll_pwait) CALL(sys_kexec_load) CALL(sys_utimensat) CALL(sys_signalfd) /* 350 */ CALL(sys_timerfd_create) CALL(sys_eventfd) CALL(sys_fallocate) CALL(sys_timerfd_settime) CALL(sys_timerfd_gettime) /* 355 */ CALL(sys_signalfd4) CALL(sys_eventfd2) CALL(sys_epoll_create1) CALL(sys_dup3) CALL(sys_pipe2) /* 360 */ CALL(sys_inotify_init1) CALL(sys_preadv) CALL(sys_pwritev) CALL(sys_rt_tgsigqueueinfo) CALL(sys_perf_event_open) /* 365 */ CALL(sys_recvmmsg) CALL(sys_accept4) CALL(sys_fanotify_init) CALL(sys_fanotify_mark) CALL(sys_prlimit64) /* 370 */ CALL(sys_clock_adjtime) #ifndef syscalls_counted .equ syscalls_padding, ((NR_syscalls + 3) & ~3) - NR_syscalls #define syscalls_counted #endif .rept syscalls_padding CALL(sys_ni_syscall) .endr
在entry-common.S中
#define CALL(x) .long x
这样就构成了
sys_call_table
.long sys_restart_syscall
.long sys_exit
...
.long sys_clock_adjtime
表
根据传递进来的swi操作码值,查表获取操作码对应的项将该项保存的系统调用函数指针地址给到pc
程序就跑到pc去执行系统调用函数
三.相关的strace命令交叉编译
1.官网下载
http://sourceforge.net/projects/strace/
版本strace-4.8.tar.xz
2.解压
xz -d strace-4.8.tar.xz
tar -xvf strace-4.8.tar
3../configure --host=arm-linux CC=arm-none-linux-gnueabi-gcc LD=arm-none-linux-gnueabi-ld
配置生成makefile
4.make
5.生产stace文件