Re: [Patch]: write_kmem above high_memory

[Alan Cox]

> > functions, and instead protect the read/writes with a exception table
> > entry similar to copy_from/to_user. Only drawback is that it needs
> > per architecture support.
> >
> 
> set_fs(KERNEL_DS) + get_user()/__get_user()?
> 
> BUT: that's dangerous, because we might read from the mmap'ed io space
> of a hardware device.

You are not guaranteed to get exception faults on invalid writes. Not all
platforms support them even. Eg i386 writes to user pages marked R/O will
not fault.