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bpf: fix a libbpf loader issue

PATCH Applied Yonghong Song 3 participants 3 messages Nov 22, 2018

Subsystems (4)
Networking Network drivers BPF libbpf
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Yonghong Song

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#0 lore raw

PATCH 1/1 bpf: fix a libbpf loader issue

Commit 2993e0515bb4 ("tools/bpf: add support to read .BTF.ext sections") added support to read .BTF.ext sections from an object file, create and pass prog_btf_fd and func_info to the kernel.

The program btf_fd (prog->btf_fd) is initialized to be -1 to please zclose so we do not need special handling dur prog close. Passing -1 to the kernel, however, will cause loading error. Passing btf_fd 0 to the kernel if prog->btf_fd is invalid fixed the problem.

Fixes 2993e0515bb4 ("tools/bpf: add support to read .BTF.ext sections")
Reported-by Andrey Ignatov <[email protected]>
Reported-by Emre Cantimur <[email protected]>
Tested-by Andrey Ignatov <[email protected]>
Signed-off-by Yonghong Song <[email protected]>
---
 tools/lib/bpf/libbpf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
tools/lib/bpf/libbpf.c +1 -1
index cb6565d79603..f022ac82e882 100644
@@ -1387,7 +1387,7 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
 	load_attr.license = license;
 	load_attr.kern_version = kern_version;
 	load_attr.prog_ifindex = prog->prog_ifindex;
-	load_attr.prog_btf_fd = prog->btf_fd;
+	load_attr.prog_btf_fd = prog->btf_fd >= 0 ? prog->btf_fd : 0;
 	load_attr.func_info = prog->func_info;
 	load_attr.func_info_rec_size = prog->func_info_rec_size;
 	load_attr.func_info_cnt = func_info_cnt;
Signature · 1 line
2.17.1
Acked-by on v1 1/1
#1 lore raw
Quoted 9 lines · Yonghong Song

Commit 2993e0515bb4 ("tools/bpf: add support to read .BTF.ext sections") added support to read .BTF.ext sections from an object file, create and pass prog_btf_fd and func_info to the kernel.

The program btf_fd (prog->btf_fd) is initialized to be -1 to please zclose so we do not need special handling dur prog close. Passing -1 to the kernel, however, will cause loading error. Passing btf_fd 0 to the kernel if prog->btf_fd is invalid fixed the problem.

Acked-by Martin KaFai Lau <[email protected]>
maintainer Applied
#2 lore raw
In reply to Yonghong Song
Quoted 10 lines · Yonghong Song

Commit 2993e0515bb4 ("tools/bpf: add support to read .BTF.ext sections") added support to read .BTF.ext sections from an object file, create and pass prog_btf_fd and func_info to the kernel.

The program btf_fd (prog->btf_fd) is initialized to be -1 to please zclose so we do not need special handling dur prog close. Passing -1 to the kernel, however, will cause loading error. Passing btf_fd 0 to the kernel if prog->btf_fd is invalid fixed the problem.

Quoted 5 lines
Fixes 2993e0515bb4 ("tools/bpf: add support to read .BTF.ext sections")
Reported-by Andrey Ignatov <[email protected]>
Reported-by Emre Cantimur <[email protected]>
Tested-by Andrey Ignatov <[email protected]>
Signed-off-by Yonghong Song <[email protected]>

Applied, thanks!