Re: [PATCH bpf-next v4 6/8] selftests/bpf: Add weak/typeless ksym test for light skeleton

Also, avoid using CO-RE features, as lskel doesn't support CO-RE, yet.
Include both light and libbpf skeleton in same file to test both of them
together.

In c48e51c8b07a ("bpf: selftests: Add selftests for module kfunc support"),
I added support for generating both lskel and libbpf skel for a BPF
object, however the name parameter for bpftool caused collisions when
included in same file together. This meant that every test needed a
separate file for a libbpf/light skeleton separation instead of
subtests.

Change that by appending a "_light" suffix to the name for files listed
in LSKELS_EXTRA, such that both light and libbpf skeleton can be used in
the same file for subtests, leading to better code sharing.

While at it, improve the build output by saying GEN-LSKEL instead of
GEN-SKEL for light skeleton generation recipe.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
 tools/testing/selftests/bpf/Makefile          |  7 ++--
 .../selftests/bpf/prog_tests/ksyms_btf.c      | 35 +++++++++++++++-
 .../selftests/bpf/prog_tests/ksyms_module.c   | 40 +++++++++++++++++--
 .../bpf/prog_tests/ksyms_module_libbpf.c      | 28 -------------
 .../selftests/bpf/progs/test_ksyms_weak.c     |  3 +-
 5 files changed, 74 insertions(+), 39 deletions(-)
 delete mode 100644 tools/testing/selftests/bpf/prog_tests/ksyms_module_libbpf.c

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 498222543c37..1c3c8befc249 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile

@@ -325,7 +325,7 @@ LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h               \
 LSKELS := kfunc_call_test.c fentry_test.c fexit_test.c fexit_sleep.c \
        test_ringbuf.c atomics.c trace_printk.c trace_vprintk.c
 # Generate both light skeleton and libbpf skeleton for these
-LSKELS_EXTRA := test_ksyms_module.c
+LSKELS_EXTRA := test_ksyms_module.c test_ksyms_weak.c
 SKEL_BLACKLIST += $$(LSKELS)

 test_static_linked.skel.h-deps := test_static_linked1.o test_static_linked2.o

@@ -399,12 +399,13 @@ $(TRUNNER_BPF_SKELS): %.skel.h: %.o $(BPFTOOL) | $(TRUNNER_OUTPUT)
        $(Q)$$(BPFTOOL) gen skeleton $$(<:.o=.linked3.o) name $$(notdir $$(<:.o=)) > $$@

 $(TRUNNER_BPF_LSKELS): %.lskel.h: %.o $(BPFTOOL) | $(TRUNNER_OUTPUT)
-       $$(call msg,GEN-SKEL,$(TRUNNER_BINARY),$$@)
+       $$(call msg,GEN-LSKEL,$(TRUNNER_BINARY),$$@)

        $(Q)$$(BPFTOOL) gen object $$(<:.o=.linked1.o) $$<
        $(Q)$$(BPFTOOL) gen object $$(<:.o=.linked2.o) $$(<:.o=.linked1.o)
        $(Q)$$(BPFTOOL) gen object $$(<:.o=.linked3.o) $$(<:.o=.linked2.o)
        $(Q)diff $$(<:.o=.linked2.o) $$(<:.o=.linked3.o)
-       $(Q)$$(BPFTOOL) gen skeleton -L $$(<:.o=.linked3.o) name $$(notdir $$(<:.o=)) > $$@
+       $$(eval LSKEL_NAME := $$(notdir $$(<:.o=$$(if $$(filter $$(notdir $$(<:.o=.c)),$(LSKELS_EXTRA)),_light,))))

+       $(Q)$$(BPFTOOL) gen skeleton -L $$(<:.o=.linked3.o) name $$(LSKEL_NAME) > $$@

 $(TRUNNER_BPF_SKELS_LINKED): $(TRUNNER_BPF_OBJS) $(BPFTOOL) | $(TRUNNER_OUTPUT)
        $$(call msg,LINK-BPF,$(TRUNNER_BINARY),$$(@:.skel.h=.o))