Vincenzo Mallozzi (vinjunior@xxxxxxxx) wrote:
> Hi all,
> I'm developing a module that checkpoints thread
> processes.
> In order to do the checkpoint, I use get_fs() and
> set_fs() instructions. The way I use them is as
> follow:
>
> checkpoint_function()
> {
> fs = get_fs();
> set_fs(KERNEL_DS);
>
> INSTRUCTIONS TO SAVE MEMORY DESCRIPTOR
>
> set_fs(fs);
> }
>
> restore_function()
> {
> fs = get_fs();
> set_fs(KERNEL_DS);
>
> INSTRUCTIONS TO RESTORE MEMORY DESCRIPTOR
>
> set_fs(fs);
> }
>
> When I execute checkpoint_function(), all seems to go
> well.
> But when I execute restore_function, a "general
> protection fault" error is returned.
> If I omit the instructions get_fs and set_fs, no error
> of this type is returned (but the checkpoint does not
> work well).
> Can anyone help me on the usage of these instructions.
> I've also found some previous emails regarding them,
> but I've not well understood in which way get_fs and
> set_fs must be applied in my module.
> I've also read some checkpoint tools, e.g. CRACK, in
> which they are used in about the same way I do it.
> Thanks.
> Vincenzo Mallozzi.
Hi,
I guess restore_function() is not used in a good context.
I imagine checkpoint_function() is used in init_module() ? SO in user
context (modprobe or insmod).
but perhaps I say some mistakes.
BUt what I say is that a pointer to your code is better than an
extract...
Have a nice day,
~Christophe
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