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

[Constantine Gavrilov <constg@qlusters.com>]

Arnd Bergmann wrote:

>On Montag, 13. September 2004 16:04, Constantine Gavrilov wrote:
>  
>
>>We have a piece of kernel code that calls some system calls in kernel 
>>context (from a process with mm and a daemonized kernel thread that does 
>>not have mm). This works fine on IA64 and i386 architectures.
>>    
>>
>
>You can find the list of system calls that are supposed to work
>from kernel space in asm/unistd.h inside #ifdef __KERNEL__SYSCALLS__.
>On current kernels, that list only contains execve(), which should
>be avoided as well in favor of call_usermodehelper. Other calls
>might work on some architectures but that is not a supported
>interface any more.
>
>You could call the sys_* functions directly if they are exported,
>but it is unlikely that such code gets integrated in the mainline
>kernel.
>
>The real answer for your problem highly depends on which syscalls
>you want to use.
>
>	Arnd <><
>  
>
I can implement differently what I want, though it will be somewhat 
kludgy and kernel depenedent (depends on a version and distribution). I 
wanted to avoid that. Since what I write is really an application and 
not interface, it was very "native" to use application syscall approach.

My real problem is not how to implement it. I want to understand this 
specific x86_64 problem.

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