Hi!
On Tue, Aug 4, 2020 at 10:44 PM Ilya Leoshkevich <iii@xxxxxxxxxxxxx> wrote:
>
> On Tue, 2020-08-04 at 20:40 +0300, Yauheni Kaliuta wrote:
> > Hi!
> >
> > I have a failure (crash) of selftests/bpf/test_kmod.sh on s390.
> >
> > The problem comes with loading with
> >
> > sysctl -w net.core.bpf_jit_harden=2
> >
> > In that case the program (lib/test_bpf.c):
> >
> > static int bpf_fill_maxinsns1(struct bpf_test *self)
> > {
> > unsigned int len = BPF_MAXINSNS;
> > struct sock_filter *insn;
> > __u32 k = ~0;
> > int i;
> >
> > insn = kmalloc_array(len, sizeof(*insn), GFP_KERNEL);
> > if (!insn)
> > return -ENOMEM;
> >
> > for (i = 0; i < len; i++, k--)
> > insn[i] = __BPF_STMT(BPF_RET | BPF_K, k);
> >
> > self->u.ptr.insns = insn;
> > self->u.ptr.len = len;
> >
> > return 0;
> > }
> >
> > after blinding and jiting is 98362 bytes for me and it does not fit
> > 16bit offset for BRC 15,.. command where BPF_EXIT | BPF_JMP is
> > translated.
> >
> > What is the easiest way to use BRCL for large offset here?
> >
> > Thanks!
>
> Hi Yauheni!
>
> Did you try bpf-next, specifically with commit 5fa6974471c5 ("s390/bpf:
> Use brcl for jumping to exit_ip if necessary")? This was supposed to
> fix this problem.
Ah, thanks a lot! I missed it.
--
WBR, Yauheni
