Re: copy_from_user() fixu
Richard Gooch (rgooch@atnf.csiro.au)
Wed, 26 Aug 1998 14:28:39 +1000
Alexander Kjeldaas writes:
> On Tue, Aug 25, 1998 at 05:37:39PM +1000, Richard Gooch wrote:
> >
> > I can't sanitise the input: I don't know what pointer the application
> > will pass. Trapping SEGV is a performance bugger: I have to install a
> > signal handler before every pseudo-syscall and restore it afterwards
> > (my library can't steal signals).
> >
>
> What if we created a faster way to handle signals. This is something
> I'd like for other applications such as JIT-compilers. My idea for
> doing this is to map a page from kernel-memory into each process.
> This will be the exception-handler. Exceptions are caught directly in
> user-space (possible on i386). This code will decide whether the
> exception is "dangerous" (routed back to the kernel), or can be
> handled by the user.
>
> Similarly, installing a signal-handler could be done using a write to
> a special page.
That sounds interesting. However, how do you handle threads?
Regards,
Richard....
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