s390x BPF JIT failures with test_bpf

Kleber Souza
2018-06-27T09:40:23Z

Hi,

When I load the test_bpf module from mainline (v4.18-rc2) with
CONFIG_BPF_JIT_ALWAYS_ON=y on a s390x system I get the following errors:

test_bpf: #289 BPF_MAXINSNS: Ctx heavy transformations FAIL to
prog_create err=-524 len=4096
test_bpf: #290 BPF_MAXINSNS: Call heavy transformations FAIL to
prog_create err=-524 len=4096
[...]
test_bpf: #296 BPF_MAXINSNS: exec all MSH FAIL to prog_create err=-524
len=4096
test_bpf: #297 BPF_MAXINSNS: ld_abs+get_processor_id FAIL to prog_create
err=-524 len=4096

From a quick look at the code it seems that
arch/s390/net/bpf_jit_comp.c:bpf_int_jit_compile() is failing to JIT
compile the test code.

Are those failures expected and could be flagged with FLAG_EXPECTED_FAIL
on lib/test_bpf.c or are those caused by some issue with the s390x JIT
compiler that needs to be fixed?

Thanks,
Kleber