From: Fathi Boudra fathi.boudra@linaro.org

[ Upstream commit 5bbc73a841d7f0bbe025a342146dde462a796a5a ]

seccomp_bpf fails to build due to undefined reference errors:

aarch64-linaro-linux-gcc --sysroot=/build/tmp-rpb-glibc/sysroots/hikey -O2 -pipe -g -feliminate-unused-debug-types -Wl,-no-as-needed -Wall -Wl,-O1 -Wl,--hash-style=gnu -Wl,--as-needed -lpthread seccomp_bpf.c -o /build/tmp-rpb-glibc/work/hikey-linaro-linux/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf /tmp/ccrlR3MW.o: In function `tsync_sibling': /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1920: undefined reference to `sem_post' /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1920: undefined reference to `sem_post' /tmp/ccrlR3MW.o: In function `TSYNC_setup': /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1863: undefined reference to `sem_init' /tmp/ccrlR3MW.o: In function `TSYNC_teardown': /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1904: undefined reference to `sem_destroy' /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1897: undefined reference to `pthread_kill' /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1898: undefined reference to `pthread_cancel' /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1899: undefined reference to `pthread_join' /tmp/ccrlR3MW.o: In function `tsync_start_sibling': /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1941: undefined reference to `pthread_create' /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1941: undefined reference to `pthread_create' /tmp/ccrlR3MW.o: In function `TSYNC_siblings_fail_prctl': /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1978: undefined reference to `sem_wait' /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1990: undefined reference to `pthread_join' /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1992: undefined reference to `pthread_join' /tmp/ccrlR3MW.o: In function `tsync_start_sibling': /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1941: undefined reference to `pthread_create' /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1941: undefined reference to `pthread_create' /tmp/ccrlR3MW.o: In function `TSYNC_two_siblings_with_ancestor': /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2016: undefined reference to `sem_wait' /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2032: undefined reference to `pthread_join' /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2034: undefined reference to `pthread_join' /tmp/ccrlR3MW.o: In function `tsync_start_sibling': /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1941: undefined reference to `pthread_create' /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1941: undefined reference to `pthread_create' /tmp/ccrlR3MW.o: In function `TSYNC_two_sibling_want_nnp': /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2046: undefined reference to `sem_wait' /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2058: undefined reference to `pthread_join' /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2060: undefined reference to `pthread_join' /tmp/ccrlR3MW.o: In function `tsync_start_sibling': /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1941: undefined reference to `pthread_create' /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1941: undefined reference to `pthread_create' /tmp/ccrlR3MW.o: In function `TSYNC_two_siblings_with_no_filter': /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2073: undefined reference to `sem_wait' /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2098: undefined reference to `pthread_join' /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2100: undefined reference to `pthread_join' /tmp/ccrlR3MW.o: In function `tsync_start_sibling': /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1941: undefined reference to `pthread_create' /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1941: undefined reference to `pthread_create' /tmp/ccrlR3MW.o: In function `TSYNC_two_siblings_with_one_divergence': /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2125: undefined reference to `sem_wait' /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2143: undefined reference to `pthread_join' /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2145: undefined reference to `pthread_join' /tmp/ccrlR3MW.o: In function `tsync_start_sibling': /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1941: undefined reference to `pthread_create' /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1941: undefined reference to `pthread_create' /tmp/ccrlR3MW.o: In function `TSYNC_two_siblings_not_under_filter': /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2169: undefined reference to `sem_wait' /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2202: undefined reference to `pthread_join' /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2227: undefined reference to `pthread_join' /tmp/ccrlR3MW.o: In function `tsync_start_sibling': /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1941: undefined reference to `pthread_create'

It's GNU Make and linker specific.

The default Makefile rule looks like:

$(CC) $(CFLAGS) $(LDFLAGS) $@ $^ $(LDLIBS)

When linking is done by gcc itself, no issue, but when it needs to be passed to proper ld, only LDLIBS follows and then ld cannot know what libs to link with.

More detail: https://www.gnu.org/software/make/manual/html_node/Implicit-Variables.html

LDFLAGS Extra flags to give to compilers when they are supposed to invoke the linker, ‘ld’, such as -L. Libraries (-lfoo) should be added to the LDLIBS variable instead.

LDLIBS Library flags or names given to compilers when they are supposed to invoke the linker, ‘ld’. LOADLIBES is a deprecated (but still supported) alternative to LDLIBS. Non-library linker flags, such as -L, should go in the LDFLAGS variable.

https://lkml.org/lkml/2010/2/10/362

tools/perf: libraries must come after objects

Link order matters, use LDLIBS instead of LDFLAGS to properly link against libpthread.

Signed-off-by: Fathi Boudra fathi.boudra@linaro.org Acked-by: Kees Cook keescook@chromium.org Signed-off-by: Shuah Khan shuah@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- tools/testing/selftests/seccomp/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/seccomp/Makefile b/tools/testing/selftests/seccomp/Makefile index fce7f4ce0692..1760b3e39730 100644 --- a/tools/testing/selftests/seccomp/Makefile +++ b/tools/testing/selftests/seccomp/Makefile @@ -9,7 +9,7 @@ BINARIES := seccomp_bpf seccomp_benchmark CFLAGS += -Wl,-no-as-needed -Wall

seccomp_bpf: seccomp_bpf.c ../kselftest_harness.h - $(CC) $(CFLAGS) $(LDFLAGS) -lpthread $< -o $@ + $(CC) $(CFLAGS) $(LDFLAGS) $< -lpthread -o $@

TEST_PROGS += $(BINARIES) EXTRA_CLEAN := $(BINARIES)