如何从内核空间调用Linux syscall? [英] How do I call Linux syscall from kernel space?

问题描述

我正在移植为Linux 2.4编写的linux内核模块，以便与Linux 2.6一起使用. 在代码中使用了一些通过syscallN()宏声明并包装在set_fs()调用中的系统调用. 在那些宏不存在的Linux 2.6中，我仍如何使用sycall?

I'm porting linux kernel module written for Linux 2.4 to work with Linux 2.6. Some syscalls declared through syscallN() macros and wrapped in set_fs() calls were used in the code. How can I still use sycalls in Linux 2.6 where those macros are absent?

我知道在内核平台上使用syscall是不好的口味，并且syscallN()宏在大多数平台上都是坏的.赞赏在内核空间中替换getuid，geteuid，mknod，chown，unlink，sched_yield syscall的任何合理方法.

I know it's a bad taste to use syscalls from kernel space and syscallN() macros are broken on most platforms. Any reasonable way to replace getuid, geteuid, mknod, chown, unlink, sched_yield syscalls in kernel space is appreciated.

推荐答案

current->uid和current->euid可以代替前两个.

schedule()应该适用于最后一个.

schedule() should work for the last one.

文件系统操作看起来更加复杂:您可以尝试查看是否导出了sys_chown()，sys_mknod()和sys_unlink()(可用于任何模块).如果他们有效，那就太好了.这里有一些有用的提示.否则，您必须进行更深入的研究:

The filesystem operations look more complicated: you might try and see if sys_chown(), sys_mknod(), and sys_unlink() are exported (available for use by any module). If they work, great. There are some useful tips here. Otherwise, you have to dig a little deeper:

chown系统调用在fs/open.c中定义.乍一看，我不明白为什么您不能将该代码复制到自己的"kernel_chown"函数中并进行尝试.

The chown syscall is defined in fs/open.c. At a glance I don't see why you couldn't copy that code into your own "kernel_chown" function and give it a try.

mknodat和unlink系统调用位于fs/namei.c中；他们最终最终分别调用vfs_mknod()和vfs_unlink().也许您可以复制该代码或从那里弄清楚它是如何完成的.

The mknodat and unlink syscalls are in fs/namei.c; they eventually wind up calling vfs_mknod() and vfs_unlink(), respectively. Maybe you can duplicate that code or figure out how it's done from there.

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