vmtests: check in vmlinux.h and use it for non-latest builds

Manually generate vmlinux.h based on latest.config to be used for non-latest
selftest build. This will keep bpftool and newest selftests builds succeeding,
while at runtime blacklist will skip them.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>

CHECKPOINT-COMMIT

@@ -1 +1 @@
-afa12644c877d3f627281bb6493d7ca8f9976e3d
+ca4db6389d611eee2eb7c1dfe710b62d8ea06772

travis-ci/vmtest/build_selftests.sh

@@ -11,13 +11,20 @@ if [ -f "${PREPARE_SELFTESTS_SCRIPT}" ]; then
 	(cd "${REPO_ROOT}/${REPO_PATH}/tools/testing/selftests/bpf" && ${PREPARE_SELFTESTS_SCRIPT})
 fi
 
+if [[ "${KERNEL}" = 'LATEST' ]]; then
+	VMLINUX_H=
+else
+	VMLINUX_H=${VMTEST_ROOT}/vmlinux.h
+fi
+
 make \
 	CLANG=clang-${LLVM_VER} \
 	LLC=llc-${LLVM_VER} \
 	LLVM_STRIP=llvm-strip-${LLVM_VER} \
 	VMLINUX_BTF="${VMLINUX_BTF}" \
+	VMLINUX_H=${VMLINUX_H} \
 	-C "${REPO_ROOT}/${REPO_PATH}/tools/testing/selftests/bpf" \
-	-j $((4*$(nproc)))
+	-j $((2*$(nproc)))
 mkdir ${LIBBPF_PATH}/selftests
 cp -R "${REPO_ROOT}/${REPO_PATH}/tools/testing/selftests/bpf" \
 	${LIBBPF_PATH}/selftests

travis-ci/vmtest/configs/blacklist/BLACKLIST-5.5.0

@@ -22,6 +22,7 @@ fexit_test		# bpf_prog_test_tracing missing
 flow_dissector		# bpf_link-based flow dissector is in 5.8+
 flow_dissector_reattach
 get_stack_raw_tp	# exercising BPF verifier bug causing infinite loop
+ksyms			# __start_BTF has different name
 link_pinning		# bpf_link is missing
 load_bytes_relative	# new functionality in 5.8
 map_ptr			# test uses BPF_MAP_TYPE_RINGBUF, added in 5.8
@@ -43,6 +44,7 @@ skb_ctx			# ctx_{size, }_{in, out} in BPF_PROG_TEST_RUN is missing
 test_global_funcs	# kernel doesn't support BTF linkage=global on FUNCs
 test_lsm		# no BPF_LSM support
 test_overhead		# no fmod_ret support
+varlen			# verifier bug fixed in later kernels
 vmlinux			# hrtimer_nanosleep() signature changed incompatibly
 xdp_adjust_tail		# new XDP functionality added in 5.8
 xdp_attach		# IFLA_XDP_EXPECTED_FD support is missing