Daniel, On Fri, Sep 12, 2014 at 08:11:37AM +0100, Daniel Borkmann wrote: > Will, Catalin, Dave, this is more or less a heads-up: when net-next and > arm64-next tree will get both merged into Linus' tree, we will run into > a 'silent' merge conflict until someone actually runs eBPF JIT on ARM64 > and might notice (I presume) an oops when JIT is freeing bpf_prog. I'd > assume nobody actually _runs_ linux-next, but not sure about that though.
Some people do. > How do we handle this? Would I need to resend this patch when the time > comes or would you ARM64 guys take care of it automagically? ;) I think we could disable BPF for arm64 until -rc1 and re-enable it together with this patch. One comment below: > --- a/arch/arm64/net/bpf_jit_comp.c > +++ b/arch/arm64/net/bpf_jit_comp.c [...] > +static void jit_fill_hole(void *area, unsigned int size) > +{ > + /* Insert illegal UND instructions. */ > + u32 *ptr, fill_ins = 0xe7ffffff; On arm64 we don't have a guaranteed undefined instruction space (and Will tells me that on Thumb-2 for the 32-bit arm port it actually is a valid instruction, it seems that you used the same value). I think the only guaranteed way is to use the BRK #imm instruction but it requires some changes to the handling code as it is currently used for kgdb (unless you can use two instructions for filling in which could generate a NULL pointer access). -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/