Hi Seth, seth.forshee@xxxxxxxxxxxxx writes: > The tests in lib/test_bpf.c were all passing in 5.4 when using the JIT, > but some are failing in 5.7/5.8. Some of the failures are due to the > removal of BPF_SIZE_MAX causing some expected failures to pass, which I > have already send a patch for [1]. The remaining failures appear to be > regressions. I haven't tried 5.5 or 5.6, so I'm not sure exactly when > they first appeared. > > These are the tests which currently fail: > > test_bpf: #37 INT: MUL_X jited:1 ret -1 != 1 FAIL (1 times) > test_bpf: #42 INT: SUB jited:1 ret -55 != 11 FAIL (1 times) > test_bpf: #44 INT: MUL jited:1 ret 439084800 != 903446258 FAIL (1 times) > test_bpf: #49 INT: shifts by register jited:1 ret -617 != -1 FAIL (1 times) > test_bpf: #371 JNE signed compare, test 1 jited:1 ret 2 != 1 FAIL (1 times) > test_bpf: #372 JNE signed compare, test 2 jited:1 ret 2 != 1 FAIL (1 times) > test_bpf: #374 JNE signed compare, test 4 jited:1 ret 1 != 2 FAIL (1 times) > test_bpf: #375 JNE signed compare, test 5 jited:1 ret 2 != 1 FAIL (1 times) The problem seems to be that the s390 JIT code generates a clgfi (compare logical 64 - 32 Bit) for JNE: kernel: test_bpf: #37 INT: MUL_X bpf_jit: flen=8 proglen=66 pass=4 image=0000000035b17790 from=insmod pid=574 kernel: JIT code: 00000000: a7 f4 00 03 07 e0 eb bf f0 70 00 24 c0 e1 ff ff kernel: JIT code: 00000010: ff ff c0 21 ff ff ff ff c0 31 00 00 00 03 b9 0c kernel: JIT code: 00000020: 00 23 c2 2e ff ff ff fd a7 84 00 04 a7 f4 00 05 kernel: JIT code: 00000030: c0 e1 00 00 00 01 b9 04 00 2e eb bf f0 70 00 04 kernel: JIT code: 00000040: 07 fe kernel: 000003ff800a0a48: a7f40003 brc 15,000003ff800a0a4e kernel: 000003ff800a0a4c: 07e0 bcr 14,%r0 kernel: 000003ff800a0a4e: ebbff0700024 stmg %r11,%r15,112(%r15) kernel: 000003ff800a0a54: c0e1ffffffff lgfi %r14,-1 kernel: 000003ff800a0a5a: c021ffffffff lgfi %r2,-1 kernel: 000003ff800a0a60: c03100000003 lgfi %r3,3 kernel: 000003ff800a0a66: b90c0023 msgr %r2,%r3 kernel: 000003ff800a0a6a: c22efffffffd clgfi %r2,4294967293 kernel: 000003ff800a0a70: a7840004 brc 8,000003ff800a0a78 kernel: 000003ff800a0a74: a7f40005 brc 15,000003ff800a0a7e kernel: 000003ff800a0a78: c0e100000001 lgfi %r14,1 kernel: 000003ff800a0a7e: b904002e lgr %r2,%r14 kernel: 000003ff800a0a82: ebbff0700004 lmg %r11,%r15,112(%r15) kernel: 000003ff800a0a88: 07fe bcr 15,%r14 kernel: jited:1 ret -1 != 1 FAIL (1 times) which in the MUL_X case compares than 0xfffffffffffffffd with 0xfffffffd, which is wrong. Changing this to a proper compare fixes all the test cases for me. Thanks for reporting! Regards Sven
