strange behaviour on v4.4 kernels with libseccomp v2.3.1

[xnox]

Hello,

I'm in a i686 chroot, and using scmp_sys_resolver I see multiple regression with syscall look-ups. The tests I run is to check that number->name->number lookups are roundtrip safe, and they appear to not be as per below:

# ./scmp_sys_resolver 373
shutdown
# ./scmp_sys_resolver shutdown
-113
# ./scmp_sys_resolver '\-113'
-1
# ./scmp_sys_resolver -t shutdown
102
# ./scmp_sys_resolver 102
socketcall

My expectation was for the output to just be:

# ./scmp_sys_resolver 373
shutdown
# ./scmp_sys_resolver shutdown
373

I see this regression for other syscalls too, on i686 and on s390x architectures.
amd64 and ppc64el pass correctly.

s390x failures:

FAIL: 357 (recvmmsg) != recvmmsg (-119)
FAIL: 358 (sendmmsg) != sendmmsg (-120)
FAIL: 359 (socket) != socket (-101)
FAIL: 360 (socketpair) != socketpair (-108)
FAIL: 361 (bind) != bind (-102)
FAIL: 362 (connect) != connect (-103)
FAIL: 363 (listen) != listen (-104)
FAIL: 364 (accept4) != accept4 (-118)
FAIL: 365 (getsockopt) != getsockopt (-115)
FAIL: 366 (setsockopt) != setsockopt (-114)
FAIL: 367 (getsockname) != getsockname (-106)
FAIL: 368 (getpeername) != getpeername (-107)
FAIL: 369 (sendto) != sendto (-111)
FAIL: 370 (sendmsg) != sendmsg (-116)
FAIL: 371 (recvfrom) != recvfrom (-112)
FAIL: 372 (recvmsg) != recvmsg (-117)
FAIL: 373 (shutdown) != shutdown (-113)

i686 failures:

FAIL: 337 (recvmmsg) != recvmmsg (-119)
FAIL: 345 (sendmmsg) != sendmmsg (-120)
FAIL: 359 (socket) != socket (-101)
FAIL: 360 (socketpair) != socketpair (-108)
FAIL: 361 (bind) != bind (-102)
FAIL: 362 (connect) != connect (-103)
FAIL: 363 (listen) != listen (-104)
FAIL: 364 (accept4) != accept4 (-118)
FAIL: 365 (getsockopt) != getsockopt (-115)
FAIL: 366 (setsockopt) != setsockopt (-114)
FAIL: 367 (getsockname) != getsockname (-106)
FAIL: 368 (getpeername) != getpeername (-107)
FAIL: 369 (sendto) != sendto (-111)
FAIL: 370 (sendmsg) != sendmsg (-116)
FAIL: 371 (recvfrom) != recvfrom (-112)
FAIL: 372 (recvmsg) != recvmsg (-117)
FAIL: 373 (shutdown) != shutdown (-113)

Are my expectation somehow wrong? is v4.5 kernel required for v2.3.1 release? Is there a bug in compat between kernel versions?

[xnox]

Actually this is maybe a non-bug, given 73d83e4

[xnox]

silly me

# scmp_sys_resolver -- -113
shutdown