On 06/27/2018 12:13 PM, Kleber Souza wrote: > On 06/27/18 12:01, Daniel Borkmann wrote: >> On 06/27/2018 11:40 AM, Kleber Souza wrote: >> [...] >>> 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? >> >> JIT doesn't guarantee in general to map really all programs to native insns, >> so some, mostly crafted corner cases could fail. E.g. x86-64 JIT doesn't converge >> on some programs in test_bpf.c and thus falls back to interpreter or simply >> rejects the program in case of CONFIG_BPF_JIT_ALWAYS_ON=y. Above would seem >> likely that it's hitting the BPF_SIZE_MAX that s390 would do. I think it might >> make sense to either have the FLAG_EXPECTED_FAIL in lib/test_bpf.c more fine >> grained as a flag per arch, so we could say it's expected to fail on e.g. s390 >> but not on x86 and the like, or just denote it as 'could potentially fail but >> doesn't have to be the case everywhere'. > > Thank you for your reply. I will run some more tests to make sure we are > hitting BPF_SIZE_MAX or what exactly is failing and send a patch to flag > it conditionally for s390x. Sounds good, thanks! In any case, please let us know your findings. Best, Daniel -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
