Re: Calling syscalls from x86-64 kernel results in a crash on Opteronmachines

[Constantine Gavrilov]

Christoph Hellwig wrote:

> On Mon, Sep 13, 2004 at 05:04:17PM +0300, Constantine Gavrilov wrote:
>  
>
> > Hello:
> >
> > We have a piece of kernel code that calls some system calls in kernel 
> > context (
> >    
>
> Which you shouldn't do in the first place.
>  

Function kernel_thread() on i386 is implemented by putting the args to 
appropriate regs and calling int 0x80, resulting in a system call 
clone() on i386.

I have also found the "syscall" instruction in x86-64 kernel specific 
code (it does not call _syscall() macros directly, though). So, 
"shouldn't do" is a bit too strong.

What I am writing is an application, and not interface. As such, it is 
not much different from its requierements from a user-space application. 
If user-space application may call system calls, why a kernel space 
application cannot?

And BTW, kernel-space applications have their own place even if the 
concept seems foreign to you.

--
----------------------------------------
Constantine Gavrilov
Kernel Developer
Qlusters Software Ltd
1 Azrieli Center, Tel-Aviv
Phone: +972-3-6081977
Fax:   +972-3-6081841
----------------------------------------


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/