Re: [Xen-devel] Building Xen with structures thread_info/task_struct

[Frederic Beck <frederic.beck@xxxxxxxx>]

Hello

I finally wrote a module and defined two new syscalls to get the PID
and the comm from the thread_info structure (well it's from the
task_struct contained in the thread_info one). The syscalls are
dynamically added in the sys_call_table.

My module works and in user mode i can call my syscalls with the
function syscall. However, it seems that this function is not defined
in Xen (it's in /usr/include/unistd.h).

How can i make that work ?

Do I have to add the module source in Xen and try to link it directly
into Xen and forget about my module ? But if i do so i will have
troubles again with the task_struct or thread_info, which is why i was
trying to do it through the module.

I'm getting out of ideas. Any clue ?

Thanks

Regards
Fred


Le Mon, 2 Feb 2009 10:52:21 +0100,
Frederic Beck <frederic.beck@xxxxxxxx> a Ãcrit :

> Hello
> 
> Le Sat, 31 Jan 2009 12:57:04 +0100,
> Bastian Blank <bastian@xxxxxxxxxxxx> a Ãcrit :
> 
> > On Thu, Jan 29, 2009 at 04:09:37PM +0100, Frederic Beck wrote:
> > > > Use the audit infrastructure within the Linux kernel.
> > > I took a quick look, audit should be running on the VM it self,
> > 
> > It is part of the Linux kernel.
> 
> Ok, so the one i was looking at does not seem to be the right one.
> I'll take a look in the kernel code then.
> 
> > > as i will have different OS running in my VMs (Linux, windows...)
> > > I'm not sure that it will permit to do what i want.
> > 
> > And AFAIK you won't be able to catch "syscalls" on HVM domains
> > anyway.
> 
> Well, i thought it was possible, because when i'm running an HVM
> domain, if i print the values of the registers in do_guest_trap from
> xen-3.3.0/xen/arch/x86/traps.c it looks like syscalls.
> 
> Maybe i misunderstood something here.
> 
> The other solution i was thinking of is adding a module in the kernel
> which would integrate a new syscall whose role would be to get the
> info from the stack address and send it back to the hypervisor via an
> integer in a first time, then maybe later on via a more complex struct
> if i need more info. 
> 
> In that case, would the hypervisor be able to use that syscall of
> should i modify something more in the hypervisor ? (like creating an
> hypercall maybe ?) This is the parts of the Xen architecture i did not
> get integrally yet.
> 
> Anyway, i'll take a look at the kernel audit first.
> 
> Thanks for the help
> 
> Regards
> Fred
> 
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