On Fri, Oct 08, 2021 at 02:03:49AM IST, Song Liu wrote:
> On Tue, Oct 5, 2021 at 5:29 PM Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx> wrote:
> >
> > Also, avoid using CO-RE features, as lskel doesn't support CO-RE, yet.
> > Create a file for testing libbpf skeleton as well, so that both
> > gen_loader and libbpf get tested.
> >
> > Signed-off-by: Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx>
> [...]
> > diff --git a/tools/testing/selftests/bpf/prog_tests/ksyms_weak_libbpf.c b/tools/testing/selftests/bpf/prog_tests/ksyms_weak_libbpf.c
> > new file mode 100644
> > index 000000000000..b75725e28647
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/prog_tests/ksyms_weak_libbpf.c
> > @@ -0,0 +1,31 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +
> > +#include <test_progs.h>
> > +#include "test_ksyms_weak.skel.h"
> > +
> > +void test_ksyms_weak_libbpf(void)
>
> This is (almost?) the same as test_weak_syms(), right? Why do we need both?
>
One includes lskel.h (light skeleton), the other includes skel.h (libbpf
skeleton). Trying to include both in the same file, it ends up redefining the
same struct. I am not sure whether adding a prefix/suffix to light skeleton
struct names is possible now, maybe through another option to bpftool in
addition to name?
> > +{
> > + struct test_ksyms_weak *skel;
> > + struct test_ksyms_weak__data *data;
> > + int err;
> > +
> > + skel = test_ksyms_weak__open_and_load();
> > + if (!ASSERT_OK_PTR(skel, "test_ksyms_weak__open_and_load"))
> > + return;
>
> [...]
>
> > diff --git a/tools/testing/selftests/bpf/progs/test_ksyms_weak.c b/tools/testing/selftests/bpf/progs/test_ksyms_weak.c
> > index 5f8379aadb29..521e7b99db08 100644
> > --- a/tools/testing/selftests/bpf/progs/test_ksyms_weak.c
> > +++ b/tools/testing/selftests/bpf/progs/test_ksyms_weak.c
> > @@ -21,7 +21,6 @@ __u64 out__non_existent_typed = -1;
> > extern const struct rq runqueues __ksym __weak; /* typed */
> > extern const void bpf_prog_active __ksym __weak; /* typeless */
> >
> > -
> > /* non-existent weak symbols. */
> >
> > /* typeless symbols, default to zero. */
> > @@ -38,7 +37,7 @@ int pass_handler(const void *ctx)
> > /* tests existing symbols. */
> > rq = (struct rq *)bpf_per_cpu_ptr(&runqueues, 0);
> > if (rq)
> > - out__existing_typed = rq->cpu;
> > + out__existing_typed = 0;
>
> Why do we need this change?
>
Since they share the same BPF object for generating skeleton, it needs to remove
dependency on CO-RE which gen_loader does not support.
If it is kept, we get this:
...
libbpf: // TODO core_relo: prog 0 insn[5] rq kind 0
libbpf: prog 'pass_handler': relo #0: failed to relocate: -95
libbpf: failed to perform CO-RE relocations: -95
libbpf: failed to load object 'test_ksyms_weak'
...
> > out__existing_typeless = (__u64)&bpf_prog_active;
> >
> > /* tests non-existent symbols. */
> > --
> > 2.33.0
> >
--
Kartikeya
