_syscall*宏哪儿去了？

网上有很多文档介绍如何添加自定义的系统调用的，说的都特别详细，但是定义好自定义的系统调用后，察看新生成的内核符号表System.map中也出现了自己定义的系统调用，但是在编写用户程序进行测试时，发现问题了：

_syscall0--_syscall6宏在linux/unistd.h中没有了。致使用户测试程序没法进行。

 

我查阅了内核源码和Changelogs,发现在Linux2.6.19.1中这些宏还在,如下：

 

#include

/*
 * user-visible error numbers are in the range -1 - -MAX_ERRNO: see
 *
 */
#define __syscall_return(type, res) /
do { /
 if ((unsigned long)(res) >= (unsigned long)(-MAX_ERRNO)) { /
  errno = -(res); /
  res = -1; /
 } /
 return (type) (res); /
} while (0)

/* XXX - _foo needs to be __foo, while __NR_bar could be _NR_bar. */
#define _syscall0(type,name) /
type name(void) /
{ /
long __res; /
__asm__ volatile ("int $0x80" /
 : "=a" (__res) /
 : "0" (__NR_##name)); /
__syscall_return(type,__res); /
}

#define _syscall1(type,name,type1,arg1) /
type name(type1 arg1) /
{ /
long __res; /
__asm__ volatile ("push %%ebx ; movl %2,%%ebx ; int $0x80 ; pop %%ebx" /
 : "=a" (__res) /
 : "0" (__NR_##name),"ri" ((long)(arg1)) : "memory"); /
__syscall_return(type,__res); /
}

#define _syscall2(type,name,type1,arg1,type2,arg2) /
type name(type1 arg1,type2 arg2) /
{ /
long __res; /
__asm__ volatile ("push %%ebx ; movl %2,%%ebx ; int $0x80 ; pop %%ebx" /
 : "=a" (__res) /
 : "0" (__NR_##name),"ri" ((long)(arg1)),"c" ((long)(arg2)) /
 : "memory"); /
__syscall_return(type,__res); /
}

#define _syscall3(type,name,type1,arg1,type2,arg2,type3,arg3) /
type name(type1 arg1,type2 arg2,type3 arg3) /
{ /
long __res; /
__asm__ volatile ("push %%ebx ; movl %2,%%ebx ; int $0x80 ; pop %%ebx" /
 : "=a" (__res) /
 : "0" (__NR_##name),"ri" ((long)(arg1)),"c" ((long)(arg2)), /
    "d" ((long)(arg3)) : "memory"); /
__syscall_return(type,__res); /
}

#define _syscall4(type,name,type1,arg1,type2,arg2,type3,arg3,type4,arg4) /
type name (type1 arg1, type2 arg2, type3 arg3, type4 arg4) /
{ /
long __res; /
__asm__ volatile ("push %%ebx ; movl %2,%%ebx ; int $0x80 ; pop %%ebx" /
 : "=a" (__res) /
 : "0" (__NR_##name),"ri" ((long)(arg1)),"c" ((long)(arg2)), /
   "d" ((long)(arg3)),"S" ((long)(arg4)) : "memory"); /
__syscall_return(type,__res); /
}

#define _syscall5(type,name,type1,arg1,type2,arg2,type3,arg3,type4,arg4, /
   type5,arg5) /
type name (type1 arg1,type2 arg2,type3 arg3,type4 arg4,type5 arg5) /
{ /
long __res; /
__asm__ volatile ("push %%ebx ; movl %2,%%ebx ; movl %1,%%eax ; " /
                  "int $0x80 ; pop %%ebx" /
 : "=a" (__res) /
 : "i" (__NR_##name),"ri" ((long)(arg1)),"c" ((long)(arg2)), /
   "d" ((long)(arg3)),"S" ((long)(arg4)),"D" ((long)(arg5)) /
 : "memory"); /
__syscall_return(type,__res); /
}

#define _syscall6(type,name,type1,arg1,type2,arg2,type3,arg3,type4,arg4, /
   type5,arg5,type6,arg6) /
type name (type1 arg1,type2 arg2,type3 arg3,type4 arg4,type5 arg5,type6 arg6) /
{ /
long __res; /
  struct { long __a1; long __a6; } __s = { (long)arg1, (long)arg6 }; /
__asm__ volatile ("push %%ebp ; push %%ebx ; movl 4(%2),%%ebp ; " /
                  "movl 0(%2),%%ebx ; movl %1,%%eax ; int $0x80 ; " /
                  "pop %%ebx ;  pop %%ebp" /
 : "=a" (__res) /
 : "i" (__NR_##name),"0" ((long)(&__s)),"c" ((long)(arg2)), /
   "d" ((long)(arg3)),"S" ((long)(arg4)),"D" ((long)(arg5)) /
 : "memory"); /
__syscall_return(type,__res); /
}

 

但是到了Linux2.6.20,这些宏就没有定义了。Changelog中有说是Remove these macros.原因是这些宏会导致系统安全漏洞，网上也有利用此漏洞的例子。

 

那我们以后自定义系统调用后如何调用呢？我将这些宏加入程序程序后，发现可以很好的运行。

下面是一个例子：

 

 

#include

#include

 

#include

/*
 * user-visible error numbers are in the range -1 - -MAX_ERRNO: see
 *
 */
#define __syscall_return(type, res) /
do { /
 if ((unsigned long)(res) >= (unsigned long)(-MAX_ERRNO)) { /
  errno = -(res); /
  res = -1; /
 } /
 return (type) (res); /
} while (0)

/* XXX - _foo needs to be __foo, while __NR_bar could be _NR_bar. */
#define _syscall0(type,name) /
type name(void) /
{ /
long __res; /
__asm__ volatile ("int $0x80" /
 : "=a" (__res) /
 : "0" (__NR_##name)); /
__syscall_return(type,__res); /
}

#define _syscall1(type,name,type1,arg1) /
type name(type1 arg1) /
{ /
long __res; /
__asm__ volatile ("push %%ebx ; movl %2,%%ebx ; int $0x80 ; pop %%ebx" /
 : "=a" (__res) /
 : "0" (__NR_##name),"ri" ((long)(arg1)) : "memory"); /
__syscall_return(type,__res); /
}

#define _syscall2(type,name,type1,arg1,type2,arg2) /
type name(type1 arg1,type2 arg2) /
{ /
long __res; /
__asm__ volatile ("push %%ebx ; movl %2,%%ebx ; int $0x80 ; pop %%ebx" /
 : "=a" (__res) /
 : "0" (__NR_##name),"ri" ((long)(arg1)),"c" ((long)(arg2)) /
 : "memory"); /
__syscall_return(type,__res); /
}

#define _syscall3(type,name,type1,arg1,type2,arg2,type3,arg3) /
type name(type1 arg1,type2 arg2,type3 arg3) /
{ /
long __res; /
__asm__ volatile ("push %%ebx ; movl %2,%%ebx ; int $0x80 ; pop %%ebx" /
 : "=a" (__res) /
 : "0" (__NR_##name),"ri" ((long)(arg1)),"c" ((long)(arg2)), /
    "d" ((long)(arg3)) : "memory"); /
__syscall_return(type,__res); /
}

#define _syscall4(type,name,type1,arg1,type2,arg2,type3,arg3,type4,arg4) /
type name (type1 arg1, type2 arg2, type3 arg3, type4 arg4) /
{ /
long __res; /
__asm__ volatile ("push %%ebx ; movl %2,%%ebx ; int $0x80 ; pop %%ebx" /
 : "=a" (__res) /
 : "0" (__NR_##name),"ri" ((long)(arg1)),"c" ((long)(arg2)), /
   "d" ((long)(arg3)),"S" ((long)(arg4)) : "memory"); /
__syscall_return(type,__res); /
}

#define _syscall5(type,name,type1,arg1,type2,arg2,type3,arg3,type4,arg4, /
   type5,arg5) /
type name (type1 arg1,type2 arg2,type3 arg3,type4 arg4,type5 arg5) /
{ /
long __res; /
__asm__ volatile ("push %%ebx ; movl %2,%%ebx ; movl %1,%%eax ; " /
                  "int $0x80 ; pop %%ebx" /
 : "=a" (__res) /
 : "i" (__NR_##name),"ri" ((long)(arg1)),"c" ((long)(arg2)), /
   "d" ((long)(arg3)),"S" ((long)(arg4)),"D" ((long)(arg5)) /
 : "memory"); /
__syscall_return(type,__res); /
}

#define _syscall6(type,name,type1,arg1,type2,arg2,type3,arg3,type4,arg4, /
   type5,arg5,type6,arg6) /
type name (type1 arg1,type2 arg2,type3 arg3,type4 arg4,type5 arg5,type6 arg6) /
{ /
long __res; /
  struct { long __a1; long __a6; } __s = { (long)arg1, (long)arg6 }; /
__asm__ volatile ("push %%ebp ; push %%ebx ; movl 4(%2),%%ebp ; " /
                  "movl 0(%2),%%ebx ; movl %1,%%eax ; int $0x80 ; " /
                  "pop %%ebx ;  pop %%ebp" /
 : "=a" (__res) /
 : "i" (__NR_##name),"0" ((long)(&__s)),"c" ((long)(arg2)), /
   "d" ((long)(arg3)),"S" ((long)(arg4)),"D" ((long)(arg5)) /
 : "memory"); /
__syscall_return(type,__res); /
}

 

#define __NR_mycall 325

_syscall1(int,mycall,int,rtvalue)

 

int main()

{

printf("mycall(100)=%d/n",mycall(100));

}

 

 

自定义的系统调用原型是

asmlinkage sys_mycall(int number)

{

return number;

}