From 2047f1d8ba287d208272b6e26360d1a53f7ebf7d Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Thu, 9 Feb 2017 19:56:27 +1100 Subject: [PATCH] selftests: Fix the .c linking rule Currently we can't build some tests, for example: $ make -C tools/testing/selftests/ TARGETS=vm ... gcc -Wall -I ../../../../usr/include -lrt -lpthread ../../../../usr/include/linux/kernel.h userfaultfd.c -o tools/testing/selftests/vm/userfaultfd /tmp/ccmOkQSM.o: In function `stress': userfaultfd.c:(.text+0xc60): undefined reference to `pthread_create' userfaultfd.c:(.text+0xca5): undefined reference to `pthread_create' userfaultfd.c:(.text+0xcee): undefined reference to `pthread_create' userfaultfd.c:(.text+0xd30): undefined reference to `pthread_create' userfaultfd.c:(.text+0xd77): undefined reference to `pthread_join' userfaultfd.c:(.text+0xe7d): undefined reference to `pthread_join' userfaultfd.c:(.text+0xe9f): undefined reference to `pthread_cancel' userfaultfd.c:(.text+0xec6): undefined reference to `pthread_join' userfaultfd.c:(.text+0xf14): undefined reference to `pthread_join' /tmp/ccmOkQSM.o: In function `userfaultfd_stress': userfaultfd.c:(.text+0x13e2): undefined reference to `pthread_attr_setstacksize' collect2: error: ld returned 1 exit status This is because the rule for linking .c files to binaries is incorrect. The first bug is that it uses $< (first prerequisite) instead of $^ (all preqrequisites), fix it by using ^$. Secondly the ordering of the prerequisites vs $(LDLIBS) is wrong, meaning on toolchains that use --as-needed we fail to link (as above). Fix that by placing $(LDLIBS) *after* ^$. Finally switch to using the default rule $(LINK.c), so that we get $(CPPFLAGS) etc. included. Fixes: a8ba798bc8ec ("selftests: enable O and KBUILD_OUTPUT") Signed-off-by: Michael Ellerman Tested by: Bamvor Jian Zhang Signed-off-by: Shuah Khan --- tools/testing/selftests/lib.mk | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/testing/selftests/lib.mk b/tools/testing/selftests/lib.mk index 17ed4bbe3963..98841c54763a 100644 --- a/tools/testing/selftests/lib.mk +++ b/tools/testing/selftests/lib.mk @@ -51,7 +51,7 @@ clean: $(RM) -r $(TEST_GEN_PROGS) $(TEST_GEN_PROGS_EXTENDED) $(TEST_GEN_FILES) $(EXTRA_CLEAN) $(OUTPUT)/%:%.c - $(CC) $(CFLAGS) $(LDFLAGS) $(LDLIBS) $< -o $@ + $(LINK.c) $^ $(LDLIBS) -o $@ $(OUTPUT)/%.o:%.S $(CC) $(ASFLAGS) -c $< -o $@ -- 2.20.1