Existing BTF_ID_LIST used a local static variable
to store btf_ids. This patch provided a new macro
BTF_ID_LIST_GLOBAL to store btf_ids in a global
variable which can be shared among multiple files.
The existing BTF_ID_LIST is still retained.
Two reasons. First, BTF_ID_LIST is also used to build
btf_ids for helper arguments which typically
is an array of 5. Since typically different
helpers have different signature, it makes
little sense to share them. Second, some
current computed btf_ids are indeed local.
If later those btf_ids are shared between
different files, they can use BTF_ID_LIST_GLOBAL then.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Link: https://lore.kernel.org/bpf/20200720163401.1393159-1-yhs@fb.com
==================
BPF Selftest Notes
==================
General instructions on running selftests can be found in
`Documentation/bpf/bpf_devel_QA.rst`_.
Additional information about selftest failures are
documented here.
bpf_iter test failures with clang/llvm 10.0.0
=============================================
With clang/llvm 10.0.0, the following two bpf_iter tests failed:
* ``bpf_iter/ipv6_route``
* ``bpf_iter/netlink``
The symptom for ``bpf_iter/ipv6_route`` looks like
.. code-block:: c
2: (79) r8 = *(u64 *)(r1 +8)
...
14: (bf) r2 = r8
15: (0f) r2 += r1
; BPF_SEQ_PRINTF(seq, "%pi6 %02x ", &rt->fib6_dst.addr, rt->fib6_dst.plen);
16: (7b) *(u64 *)(r8 +64) = r2
only read is supported
The symptom for ``bpf_iter/netlink`` looks like
.. code-block:: c
; struct netlink_sock *nlk = ctx->sk;
2: (79) r7 = *(u64 *)(r1 +8)
...
15: (bf) r2 = r7
16: (0f) r2 += r1
; BPF_SEQ_PRINTF(seq, "%pK %-3d ", s, s->sk_protocol);
17: (7b) *(u64 *)(r7 +0) = r2
only read is supported
This is due to a llvm BPF backend bug. The fix
https://reviews.llvm.org/D78466
has been pushed to llvm 10.x release branch and will be
available in 10.0.1. The fix is available in llvm 11.0.0 trunk.
0f12e584b2