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 <m...@ellerman.id.au>
---
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 $@
--
2.7.4
