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99aacebecb("selftests: do not use .ONESHELL") removed .ONESHELL, which changes how Makefile "silences" multi-command target recipes. selftests/bpf's Makefile relied (a somewhat unknowingly) on .ONESHELL behavior of silencing all commands within the recipe if the first command contains @ symbol. Removing .ONESHELL exposed this hack. This patch fixes the issue by explicitly silencing each command with $(Q). Also explicitly define fallback rule for building *.o from *.c, instead of relying on non-silent inherited rule. This was causing a non-silent output for bench.o object file. Fixes:92f7440ecc("selftests/bpf: More succinct Makefile output") Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200807033058.848677-1-andriin@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.