netdev - [PATCH bpf-next] libbpf: ignore .eh_frame sections when parsing elf files

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Message-Id: <20210629110923.580029-1-toke@redhat.com>
Date:   Tue, 29 Jun 2021 13:09:23 +0200
From:   Toke Høiland-Jørgensen <toke@...hat.com>
To:     Andrii Nakryiko <andrii@...nel.org>
Cc:     bpf@...r.kernel.org, netdev@...r.kernel.org,
        Toke Høiland-Jørgensen <toke@...hat.com>
Subject: [PATCH bpf-next] libbpf: ignore .eh_frame sections when parsing elf files

The .eh_frame and .rel.eh_frame sections will be present in BPF object
files when compiled using a multi-stage compile pipe like in samples/bpf.
This produces errors when loading such a file with libbpf. While the errors
are technically harmless, they look odd and confuse users. So add .eh_frame
sections to is_sec_name_dwarf() so they will also be ignored by libbpf
processing. This gets rid of output like this from samples/bpf:

libbpf: elf: skipping unrecognized data section(32) .eh_frame
libbpf: elf: skipping relo section(33) .rel.eh_frame for section(32) .eh_frame

Signed-off-by: Toke Høiland-Jørgensen <toke@...hat.com>
---
 tools/lib/bpf/libbpf.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 1e04ce724240..676af6be5961 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -2906,7 +2906,8 @@ static Elf_Data *elf_sec_data(const struct bpf_object *obj, Elf_Scn *scn)
 static bool is_sec_name_dwarf(const char *name)
 {
 	/* approximation, but the actual list is too long */
-	return strncmp(name, ".debug_", sizeof(".debug_") - 1) == 0;
+	return (strncmp(name, ".debug_", sizeof(".debug_") - 1) == 0 ||
+		strncmp(name, ".eh_frame", sizeof(".eh_frame") - 1) == 0);
 }
 
 static bool ignore_elf_section(GElf_Shdr *hdr, const char *name)
-- 
2.32.0