How to invoke any kernel function?

Question

I know that Kprobes can be used to probe any kernel function. But after going through its documents I realise that it is mostly a kind of passive entity. It simply puts a probe in the middle of an execution sequence.

But what if I want to invoke any kernel function directly without bothering about the execution sequence.

How can I achieve that?

Updated:

Note: I want to invoke any kernel function inside my kernel module and not from any user space application.

Answer 1

what if I want to invoke any kernel function directly

Not all functions can be used directly at least.

Consider the following points when calling a kernel function in your case.

• kernel function from different module can be used only if it is exported using EXPORT_SYMBOL family of macros.
• static functions can't be used directly outside of that file.

Example

Function definition (i2c_smbus_read_byte_data)
http://lxr.free-electrons.com/source/drivers/i2c/i2c-core.c#L2689

Used here
http://lxr.free-electrons.com/source/drivers/i2c/i2c-core.c#L350