selftests/bpf: Add {load,search}_kallsyms_custom_local()

These two functions allow selftests to do loading/searching
kallsyms based on their specific compare functions.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240326041513.1199440-1-yonghong.song@linux.devSigned-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/trace_helpers.c

@@ -114,6 +114,11 @@ struct ksyms *load_kallsyms_local(void)
 	return load_kallsyms_local_common(ksym_cmp);
 }
 
+struct ksyms *load_kallsyms_custom_local(ksym_cmp_t cmp_cb)
+{
+	return load_kallsyms_local_common(cmp_cb);
+}
+
 int load_kallsyms(void)
 {
 	pthread_mutex_lock(&ksyms_mutex);
@@ -153,6 +158,28 @@ struct ksym *ksym_search_local(struct ksyms *ksyms, long key)
 	return &ksyms->syms[0];
 }
 
+struct ksym *search_kallsyms_custom_local(struct ksyms *ksyms, const void *p,
+					  ksym_search_cmp_t cmp_cb)
+{
+	int start = 0, mid, end = ksyms->sym_cnt;
+	struct ksym *ks;
+	int result;
+
+	while (start < end) {
+		mid = start + (end - start) / 2;
+		ks = &ksyms->syms[mid];
+		result = cmp_cb(p, ks);
+		if (result < 0)
+			end = mid;
+		else if (result > 0)
+			start = mid + 1;
+		else
+			return ks;
+	}
+
+	return NULL;
+}
+
 struct ksym *ksym_search(long key)
 {
 	if (!ksyms)

tools/testing/selftests/bpf/trace_helpers.h

@@ -14,6 +14,7 @@ struct ksym {
 struct ksyms;
 
 typedef int (*ksym_cmp_t)(const void *p1, const void *p2);
+typedef int (*ksym_search_cmp_t)(const void *p1, const struct ksym *p2);
 
 int load_kallsyms(void);
 struct ksym *ksym_search(long key);
@@ -24,6 +25,10 @@ struct ksym *ksym_search_local(struct ksyms *ksyms, long key);
 long ksym_get_addr_local(struct ksyms *ksyms, const char *name);
 void free_kallsyms_local(struct ksyms *ksyms);
 
+struct ksyms *load_kallsyms_custom_local(ksym_cmp_t cmp_cb);
+struct ksym *search_kallsyms_custom_local(struct ksyms *ksyms, const void *p1,
+					  ksym_search_cmp_t cmp_cb);
+
 /* open kallsyms and find addresses on the fly, faster than load + search. */
 int kallsyms_find(const char *sym, unsigned long long *addr);