Comment 7 for bug 1815415

Thanks for the reviews - I'll have to come up with some tests on my own then ...

In general there already are build time tests and autopkgtests in the package.
So coverage of "old calls" for regressions is already good.
Fortunately the autopkgtests seem to be extendable for an explicit verification of a few of the new calls. IMHO there is no need to modify the packages test as run on autopkgtest for these more rare calls - the are focused on use cases like snaps which they got added for.

We need to:
- add the new calls
- make it fail on unknown calls (without it says "syscall not available on this arch/kernel - as this is a syscall whitelist its ok and the error can be ignored
- remove some syscalls that never (or no more) exist(ed) that way

Note: a lot of this is kernel dependent it should work with the intended SRU target of Bionic with kernel 4.15 or 4.18, but be careful to run it there (e.g. not a LXD container on Xenials 4.4 kernel)

# Prep
$ apt install ubuntu-dev-tools build-essential linux-libc-dev libseccomp-dev libseccomp2 seccomp
$ pull-lp-source libseccomp bionic
$ cd libseccomp-2.3.1
$ export ADTTMP=$(mktemp -d); echo $ADTTMP
# run original tests as-is (should pass/fail as expected)
$ ./debian/tests/test-filter
# add new syscalls of this SRU
$ cp debian/tests/data/safe.filter debian/tests/data/newcodes.filter
$ printf "preadv2\npwritev2\npkey_mprotect\npkey_alloc\npkey_free\nget_tls\ns390_guarded_storage\ns390_sthyi\n" >> debian/tests/data/newcodes.filter
# remove unknown calls (x86 4.18 kernel)
sed -i -e '/^_exit$/d' -e '/^fstatvfs$/d' -e '/^llseek$/d' -e '/^pread$/d' -e '/^pselect$/d' -e '/^pwrite$/d' -e '/^sigtimedwait$/d' -e '/^sigwaitinfo$/d' -e '/^statvfs$/d' debian/tests/data/newcodes.filter
# make unknown call a fail
$ sed -i -e '111s/continue;/{fprintf(stderr, "failed to find %s\\n",buf);rc = -1;goto out;}/' debian/tests/src/test-seccomp.c
# run this special test and check return value
${ADTTMP}/exe ./debian/tests/data/newcodes.filter /bin/date; echo $?

Without the fix it will fail like:
DEBUG: seccomp_load_filters ./debian/tests/data/newcodes.filter
failed to find preadv2
seccomp_load_filters failed with -1
1

But with the fix applied those new calls will work:
DEBUG: seccomp_load_filters ./debian/tests/data/newcodes.filter
Tue Feb 12 07:41:05 UTC 2019
0

Tested on the PPA builds and working - adding these as SRU test & verification steps