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Subject: [PATCH  bpf  v3 1/2] bpf: Fix BTF_ID symbol generation collision
From:   Nick Desaulniers <ndesaulniers@google.com>
To:     Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <martin.lau@linux.dev>,
        Song Liu <song@kernel.org>,
        Yonghong Song <yonghong.song@linux.dev>,
        KP Singh <kpsingh@kernel.org>, Jiri Olsa <jolsa@kernel.org>
Cc:     linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@chromium.org>,
        Stanislav Fomichev <sdf@google.com>,
        Hao Luo <haoluo@google.com>,
        Nick Desaulniers <ndesaulniers@google.com>,
        stable@vger.kernel.org,
        Satya Durga Srinivasu Prabhala <quic_satyap@quicinc.com>,
        Marcus Seyfarth <m.seyfarth@gmail.com>,
        Nathan Chancellor <nathan@kernel.org>
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From: Jiri Olsa <jolsa@kernel.org>

Marcus and Satya reported an issue where BTF_ID macro generates same
symbol in separate objects and that breaks final vmlinux link.

ld.lld: error: ld-temp.o <inline asm>:14577:1: symbol
'__BTF_ID__struct__cgroup__624' is already defined

This can be triggered under specific configs when __COUNTER__ happens to
be the same for the same symbol in two different translation units,
which is already quite unlikely to happen.

Add __LINE__ number suffix to make BTF_ID symbol more unique, which is
not a complete fix, but it would help for now and meanwhile we can work
on better solution as suggested by Andrii.

Cc: stable@vger.kernel.org
Reported-by: Satya Durga Srinivasu Prabhala <quic_satyap@quicinc.com>
Reported-by: Marcus Seyfarth <m.seyfarth@gmail.com>
Closes: https://github.com/ClangBuiltLinux/linux/issues/1913
Debugged-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/bpf/CAEf4Bzb5KQ2_LmhN769ifMeSJaWfebccUasQOfQKaOd0nQ51tw@mail.gmail.com/
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
 include/linux/btf_ids.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/btf_ids.h b/include/linux/btf_ids.h
index a3462a9b8e18..a9cb10b0e2e9 100644
--- a/include/linux/btf_ids.h
+++ b/include/linux/btf_ids.h
@@ -49,7 +49,7 @@ word							\
 	____BTF_ID(symbol, word)
 
 #define __ID(prefix) \
-	__PASTE(prefix, __COUNTER__)
+	__PASTE(__PASTE(prefix, __COUNTER__), __LINE__)
 
 /*
  * The BTF_ID defines unique symbol for each ID pointing

-- 
2.42.0.459.ge4e396fd5e-goog