On 06/27/18 12:01, Daniel Borkmann wrote: > Hi Kleber, > > 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'. Hi Daniel, 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. Thanks, Kleber -- 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
