netdev - [PATCH bpf-next v5 2/3] libbpf: support detecting and attaching of writable tracepoint program

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Date:   Mon,  4 Oct 2021 17:48:56 +0800
From:   Hou Tao <hotforest@...il.com>
To:     Alexei Starovoitov <ast@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>
Cc:     Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Yonghong Song <yhs@...com>, Martin KaFai Lau <kafai@...com>,
        Ingo Molnar <mingo@...hat.com>, netdev@...r.kernel.org,
        bpf@...r.kernel.org, houtao1@...wei.com
Subject: [PATCH bpf-next v5 2/3] libbpf: support detecting and attaching of writable tracepoint program

From: Hou Tao <houtao1@...wei.com>

Program on writable tracepoint is BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE,
but its attachment is the same as BPF_PROG_TYPE_RAW_TRACEPOINT.

Signed-off-by: Hou Tao <houtao1@...wei.com>
---
 tools/lib/bpf/libbpf.c | 26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index e23f1b6b9402..25a01ad894c4 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -8029,6 +8029,8 @@ static const struct bpf_sec_def section_defs[] = {
 	SEC_DEF("tp/",			TRACEPOINT, 0, SEC_NONE, attach_tp),
 	SEC_DEF("raw_tracepoint/",	RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp),
 	SEC_DEF("raw_tp/",		RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp),
+	SEC_DEF("raw_tracepoint.w/",	RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp),
+	SEC_DEF("raw_tp.w/",		RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp),
 	SEC_DEF("tp_btf/",		TRACING, BPF_TRACE_RAW_TP, SEC_ATTACH_BTF, attach_trace),
 	SEC_DEF("fentry/",		TRACING, BPF_TRACE_FENTRY, SEC_ATTACH_BTF, attach_trace),
 	SEC_DEF("fmod_ret/",		TRACING, BPF_MODIFY_RETURN, SEC_ATTACH_BTF, attach_trace),
@@ -9786,12 +9788,26 @@ struct bpf_link *bpf_program__attach_raw_tracepoint(const struct bpf_program *pr
 
 static struct bpf_link *attach_raw_tp(const struct bpf_program *prog, long cookie)
 {
-	const char *tp_name;
+	static const char *const prefixes[] = {
+		"raw_tp/",
+		"raw_tracepoint/",
+		"raw_tp.w/",
+		"raw_tracepoint.w/",
+	};
+	size_t i;
+	const char *tp_name = NULL;
 
-	if (str_has_pfx(prog->sec_name, "raw_tp/"))
-		tp_name = prog->sec_name + sizeof("raw_tp/") - 1;
-	else
-		tp_name = prog->sec_name + sizeof("raw_tracepoint/") - 1;
+	for (i = 0; i < ARRAY_SIZE(prefixes); i++) {
+		if (str_has_pfx(prog->sec_name, prefixes[i])) {
+			tp_name = prog->sec_name + strlen(prefixes[i]);
+			break;
+		}
+	}
+	if (!tp_name) {
+		pr_warn("prog '%s': invalid section name '%s'\n",
+			prog->name, prog->sec_name);
+		return libbpf_err_ptr(-EINVAL);
+	}
 
 	return bpf_program__attach_raw_tracepoint(prog, tp_name);
 }
-- 
2.20.1