From 5c10a3dbe9220ca7bcee716c13c8a8563bcb010a Mon Sep 17 00:00:00 2001
From: Jonathan Edwards <jonathan.edwards@165gc.onmicrosoft.com>
Date: Sat, 19 Jun 2021 11:10:07 -0400
Subject: [PATCH] libbpf: Add extra BPF_PROG_TYPE check to
bpf_object__probe_loading
eBPF has been backported for RHEL 7 w/ kernel 3.10-940+ [0]. However only
the following program types are supported [1]:
BPF_PROG_TYPE_KPROBE
BPF_PROG_TYPE_TRACEPOINT
BPF_PROG_TYPE_PERF_EVENT
For libbpf this causes an EINVAL return during the bpf_object__probe_loading
call which only checks to see if programs of type BPF_PROG_TYPE_SOCKET_FILTER
can load.
The following will try BPF_PROG_TYPE_TRACEPOINT as a fallback attempt before
erroring out. BPF_PROG_TYPE_KPROBE was not a good candidate because on some
kernels it requires knowledge of the LINUX_VERSION_CODE.
[0] https://www.redhat.com/en/blog/introduction-ebpf-red-hat-enterprise-linux-7
[1] https://access.redhat.com/articles/3550581
Signed-off-by: Jonathan Edwards <jonathan.edwards@165gc.onmicrosoft.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210619151007.GA6963@165gc.onmicrosoft.com
---
tools/lib/bpf/libbpf.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 48c0ade05ab1b..1e04ce724240f 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -4000,6 +4000,10 @@ bpf_object__probe_loading(struct bpf_object *obj)
attr.license = "GPL";
ret = bpf_load_program_xattr(&attr, NULL, 0);
+ if (ret < 0) {
+ attr.prog_type = BPF_PROG_TYPE_TRACEPOINT;
+ ret = bpf_load_program_xattr(&attr, NULL, 0);
+ }
if (ret < 0) {
ret = errno;
cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg));
--
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