runqslower: Fix Makefile

Fix undefined reference linker errors when building runqslower with
gcc 7.4.0 on Ubuntu 18.04.
The issue is with misplaced -lelf, -lz options in Makefile:
$(Q)$(CC) $(CFLAGS) -lelf -lz $^ -o $@

-lelf, -lz options should follow the list of target dependencies:
$(Q)$(CC) $(CFLAGS) $^ -lelf -lz -o $@
or after substitution
cc -g -Wall runqslower.o libbpf.a -lelf -lz -o runqslower

The current order of gcc params causes failure in libelf symbols resolution,
e.g. undefined reference to `elf_memory'

Fixes: 9c01546d26 ("tools/bpf: Add runqslower tool to tools/bpf")
Signed-off-by: Julia Kartseva <hex@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/908498f794661c44dca54da9e09dc0c382df6fcb.1580425879.git.hex@fb.com
This commit is contained in:
Yulia Kartseva 2020-01-30 15:13:10 -08:00 committed by Alexei Starovoitov
parent d3e42bb0a3
commit 2577e373bb

View File

@ -41,7 +41,7 @@ clean:
$(OUTPUT)/runqslower: $(OUTPUT)/runqslower.o $(BPFOBJ)
$(call msg,BINARY,$@)
$(Q)$(CC) $(CFLAGS) -lelf -lz $^ -o $@
$(Q)$(CC) $(CFLAGS) $^ -lelf -lz -o $@
$(OUTPUT)/runqslower.o: runqslower.h $(OUTPUT)/runqslower.skel.h \
$(OUTPUT)/runqslower.bpf.o