libbpf: Add section handlers for sleepable tracepoints

Add SEC_DEF entries for sleepable tracepoint variants:
  - "tp_btf.s+"     for sleepable BTF-based raw tracepoints
  - "raw_tp.s+"     for sleepable raw tracepoints
  - "raw_tracepoint.s+" (alias)
  - "tp.s+"         for sleepable classic tracepoints
  - "tracepoint.s+" (alias)

Extract sec_name_match_prefix() to share the prefix matching logic
between attach_tp() and attach_raw_tp(), eliminating duplicated
loops and hardcoded strcmp() checks for bare section names.

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/bpf/20260422-sleepable_tracepoints-v13-5-99005dff21ef@meta.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

1 files changed, 57 insertions, 31 deletions

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 83aae7a39d36..ab2071fdd3e8 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -10018,11 +10018,16 @@ static const struct bpf_sec_def section_defs[] = {
 	SEC_DEF("netkit/peer",		SCHED_CLS, BPF_NETKIT_PEER, SEC_NONE),
 	SEC_DEF("tracepoint+",		TRACEPOINT, 0, SEC_NONE, attach_tp),
 	SEC_DEF("tp+",			TRACEPOINT, 0, SEC_NONE, attach_tp),
+	SEC_DEF("tracepoint.s+",	TRACEPOINT, 0, SEC_SLEEPABLE, attach_tp),
+	SEC_DEF("tp.s+",		TRACEPOINT, 0, SEC_SLEEPABLE, 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.s+",	RAW_TRACEPOINT, 0, SEC_SLEEPABLE, attach_raw_tp),
+	SEC_DEF("raw_tp.s+",		RAW_TRACEPOINT, 0, SEC_SLEEPABLE, 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("tp_btf.s+",		TRACING, BPF_TRACE_RAW_TP, SEC_ATTACH_BTF | SEC_SLEEPABLE, 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),
 	SEC_DEF("fexit+",		TRACING, BPF_TRACE_FEXIT, SEC_ATTACH_BTF, attach_trace),
@@ -13152,25 +13157,61 @@ struct bpf_link *bpf_program__attach_tracepoint(const struct bpf_program *prog,
 	return bpf_program__attach_tracepoint_opts(prog, tp_category, tp_name, NULL);
 }
 
+/*
+ * Match section name against a prefix array. Returns pointer past
+ * "prefix/" on match, empty string for bare sections (exact prefix
+ * match), or NULL if no prefix matches.
+ */
+static const char *sec_name_match_prefix(const char *sec_name,
+					 const char *const *prefixes,
+					 size_t n)
+{
+	size_t i;
+
+	for (i = 0; i < n; i++) {
+		size_t pfx_len;
+
+		if (!str_has_pfx(sec_name, prefixes[i]))
+			continue;
+
+		pfx_len = strlen(prefixes[i]);
+		if (sec_name[pfx_len] == '\0')
+			return sec_name + pfx_len;
+
+		if (sec_name[pfx_len] != '/' || sec_name[pfx_len + 1] == '\0')
+			continue;
+
+		return sec_name + pfx_len + 1;
+	}
+	return NULL;
+}
+
 static int attach_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link)
 {
+	static const char *const prefixes[] = {
+		"tp.s",
+		"tp",
+		"tracepoint.s",
+		"tracepoint",
+	};
 	char *sec_name, *tp_cat, *tp_name;
+	const char *match;
 
 	*link = NULL;
 
-	/* no auto-attach for SEC("tp") or SEC("tracepoint") */
-	if (strcmp(prog->sec_name, "tp") == 0 || strcmp(prog->sec_name, "tracepoint") == 0)
+	match = sec_name_match_prefix(prog->sec_name, prefixes, ARRAY_SIZE(prefixes));
+	if (!match) {
+		pr_warn("prog '%s': invalid section name '%s'\n", prog->name, prog->sec_name);
+		return -EINVAL;
+	}
+	if (!match[0]) /* bare section name no autoattach */
 		return 0;
 
 	sec_name = strdup(prog->sec_name);
 	if (!sec_name)
 		return -ENOMEM;
 
-	/* extract "tp/<category>/<name>" or "tracepoint/<category>/<name>" */
-	if (str_has_pfx(prog->sec_name, "tp/"))
-		tp_cat = sec_name + sizeof("tp/") - 1;
-	else
-		tp_cat = sec_name + sizeof("tracepoint/") - 1;
+	tp_cat = sec_name + (match - prog->sec_name);
 	tp_name = strchr(tp_cat, '/');
 	if (!tp_name) {
 		free(sec_name);
@@ -13234,37 +13275,22 @@ static int attach_raw_tp(const struct bpf_program *prog, long cookie, struct bpf
 		"raw_tracepoint",
 		"raw_tp.w",
 		"raw_tracepoint.w",
+		"raw_tp.s",
+		"raw_tracepoint.s",
 	};
-	size_t i;
-	const char *tp_name = NULL;
+	const char *match;
 
 	*link = NULL;
 
-	for (i = 0; i < ARRAY_SIZE(prefixes); i++) {
-		size_t pfx_len;
-
-		if (!str_has_pfx(prog->sec_name, prefixes[i]))
-			continue;
-
-		pfx_len = strlen(prefixes[i]);
-		/* no auto-attach case of, e.g., SEC("raw_tp") */
-		if (prog->sec_name[pfx_len] == '\0')
-			return 0;
-
-		if (prog->sec_name[pfx_len] != '/')
-			continue;
-
-		tp_name = prog->sec_name + pfx_len + 1;
-		break;
-	}
-
-	if (!tp_name) {
-		pr_warn("prog '%s': invalid section name '%s'\n",
-			prog->name, prog->sec_name);
+	match = sec_name_match_prefix(prog->sec_name, prefixes, ARRAY_SIZE(prefixes));
+	if (!match) {
+		pr_warn("prog '%s': invalid section name '%s'\n", prog->name, prog->sec_name);
 		return -EINVAL;
 	}
+	if (!match[0])
+		return 0;
 
-	*link = bpf_program__attach_raw_tracepoint(prog, tp_name);
+	*link = bpf_program__attach_raw_tracepoint(prog, match);
 	return libbpf_get_error(*link);
 }