From: Jan Seiffert <redacted>
Date: Fri, 30 Mar 2012 17:35:01 +0200

Now the helper function from filter.c for negative offsets is exported,
it can be used it in the jit to handle negative offsets.

First modify the asm load helper functions to handle:
- know positive offsets
- know negative offsets
- any offset

then the compiler can be modified to explicitly use these helper
when appropriate.

This fixes the case of a negative X register and allows to lift
the restriction that bpf programs with negative offsets can't
be jited.

Signed-off-by: Jan Seiffert <redacted>

I have only compile tested this, -ENOHARDWARE.
Can someone with more powerpc kung-fu review and maybe test this?
Esp. powerpc asm is not my strong point. I think i botched the
stack frame in the call setup. Help?

I'm not applying this until a powerpc person tests it.

Also, we have an ARM JIT in the tree which probably needs to
be fixed similarly.