selftests/bpf: Move is_jit_enabled() into testing_helpers

Currently, is_jit_enabled() is only used in test_progs, move it into
testing_helpers so that it can be used in test_verifier. While at it,
remove the second argument "0" of open() as Hou Tao suggested.

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Hou Tao <houtao1@huawei.com>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/bpf/20240123090351.2207-2-yangtiezhu@loongson.cn

tools/testing/selftests/bpf/test_progs.c

@@ -547,24 +547,6 @@ int bpf_find_map(const char *test, struct bpf_object *obj, const char *name)
 	return bpf_map__fd(map);
 }
 
-static bool is_jit_enabled(void)
-{
-	const char *jit_sysctl = "/proc/sys/net/core/bpf_jit_enable";
-	bool enabled = false;
-	int sysctl_fd;
-
-	sysctl_fd = open(jit_sysctl, 0, O_RDONLY);
-	if (sysctl_fd != -1) {
-		char tmpc;
-
-		if (read(sysctl_fd, &tmpc, sizeof(tmpc)) == 1)
-			enabled = (tmpc != '0');
-		close(sysctl_fd);
-	}
-
-	return enabled;
-}
-
 int compare_map_keys(int map1_fd, int map2_fd)
 {
 	__u32 key, next_key;

tools/testing/selftests/bpf/testing_helpers.c

@@ -457,3 +457,21 @@ int get_xlated_program(int fd_prog, struct bpf_insn **buf, __u32 *cnt)
 	*buf = NULL;
 	return -1;
 }
+
+bool is_jit_enabled(void)
+{
+	const char *jit_sysctl = "/proc/sys/net/core/bpf_jit_enable";
+	bool enabled = false;
+	int sysctl_fd;
+
+	sysctl_fd = open(jit_sysctl, O_RDONLY);
+	if (sysctl_fd != -1) {
+		char tmpc;
+
+		if (read(sysctl_fd, &tmpc, sizeof(tmpc)) == 1)
+			enabled = (tmpc != '0');
+		close(sysctl_fd);
+	}
+
+	return enabled;
+}

tools/testing/selftests/bpf/testing_helpers.h

@@ -52,5 +52,6 @@ struct bpf_insn;
  */
 int get_xlated_program(int fd_prog, struct bpf_insn **buf, __u32 *cnt);
 int testing_prog_flags(void);
+bool is_jit_enabled(void);
 
 #endif /* __TESTING_HELPERS_H */