selftests/bpf: __not_msg() tag for test_loader framework

This patch adds tags __not_msg(<msg>) and __not_msg_unpriv(<msg>).
Test fails if <msg> is found in verifier log.

If __msg_not() is situated between __msg() tags framework matches
__msg() tags first, and then checks that <msg> is not present in a
portion of a log between bracketing __msg() tags.
__msg_not() tags bracketed by a same __msg() group are effectively
unordered.

The idea is borrowed from LLVM's CheckFile with its CHECK-NOT syntax.

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250918-callchain-sensitive-liveness-v3-11-c3cd27bacc60@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 125 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/prog_tests_framework.c b/tools/testing/selftests/bpf/prog_tests/prog_tests_framework.c
index 14f2796076e0..7607cfc2408c 100644
--- a/tools/testing/selftests/bpf/prog_tests/prog_tests_framework.c
+++ b/tools/testing/selftests/bpf/prog_tests/prog_tests_framework.c
@@ -54,3 +54,128 @@ void test_prog_tests_framework(void)
 		return;
 	clear_test_state(state);
 }
+
+static void dummy_emit(const char *buf, bool force) {}
+
+void test_prog_tests_framework_expected_msgs(void)
+{
+	struct expected_msgs msgs;
+	int i, j, error_cnt;
+	const struct {
+		const char *name;
+		const char *log;
+		const char *expected;
+		struct expect_msg *pats;
+	} cases[] = {
+		{
+			.name = "simple-ok",
+			.log = "aaabbbccc",
+			.pats = (struct expect_msg[]) {
+				{ .substr = "aaa" },
+				{ .substr = "ccc" },
+				{}
+			}
+		},
+		{
+			.name = "simple-fail",
+			.log = "aaabbbddd",
+			.expected = "MATCHED    SUBSTR: 'aaa'\n"
+				    "EXPECTED   SUBSTR: 'ccc'\n",
+			.pats = (struct expect_msg[]) {
+				{ .substr = "aaa" },
+				{ .substr = "ccc" },
+				{}
+			}
+		},
+		{
+			.name = "negative-ok-mid",
+			.log = "aaabbbccc",
+			.pats = (struct expect_msg[]) {
+				{ .substr = "aaa" },
+				{ .substr = "foo", .negative = true },
+				{ .substr = "bar", .negative = true },
+				{ .substr = "ccc" },
+				{}
+			}
+		},
+		{
+			.name = "negative-ok-tail",
+			.log = "aaabbbccc",
+			.pats = (struct expect_msg[]) {
+				{ .substr = "aaa" },
+				{ .substr = "foo", .negative = true },
+				{}
+			}
+		},
+		{
+			.name = "negative-ok-head",
+			.log = "aaabbbccc",
+			.pats = (struct expect_msg[]) {
+				{ .substr = "foo", .negative = true },
+				{ .substr = "ccc" },
+				{}
+			}
+		},
+		{
+			.name = "negative-fail-head",
+			.log = "aaabbbccc",
+			.expected = "UNEXPECTED SUBSTR: 'aaa'\n",
+			.pats = (struct expect_msg[]) {
+				{ .substr = "aaa", .negative = true },
+				{ .substr = "bbb" },
+				{}
+			}
+		},
+		{
+			.name = "negative-fail-tail",
+			.log = "aaabbbccc",
+			.expected = "UNEXPECTED SUBSTR: 'ccc'\n",
+			.pats = (struct expect_msg[]) {
+				{ .substr = "bbb" },
+				{ .substr = "ccc", .negative = true },
+				{}
+			}
+		},
+		{
+			.name = "negative-fail-mid-1",
+			.log = "aaabbbccc",
+			.expected = "UNEXPECTED SUBSTR: 'bbb'\n",
+			.pats = (struct expect_msg[]) {
+				{ .substr = "aaa" },
+				{ .substr = "bbb", .negative = true },
+				{ .substr = "ccc" },
+				{}
+			}
+		},
+		{
+			.name = "negative-fail-mid-2",
+			.log = "aaabbb222ccc",
+			.expected = "UNEXPECTED SUBSTR: '222'\n",
+			.pats = (struct expect_msg[]) {
+				{ .substr = "aaa" },
+				{ .substr = "222", .negative = true },
+				{ .substr = "bbb", .negative = true },
+				{ .substr = "ccc" },
+				{}
+			}
+		}
+	};
+
+	for (i = 0; i < ARRAY_SIZE(cases); i++) {
+		if (test__start_subtest(cases[i].name)) {
+			error_cnt = env.subtest_state->error_cnt;
+			msgs.patterns = cases[i].pats;
+			msgs.cnt = 0;
+			for (j = 0; cases[i].pats[j].substr; j++)
+				msgs.cnt++;
+			validate_msgs(cases[i].log, &msgs, dummy_emit);
+			fflush(stderr);
+			env.subtest_state->error_cnt = error_cnt;
+			if (cases[i].expected)
+				ASSERT_HAS_SUBSTR(env.subtest_state->log_buf, cases[i].expected, "expected output");
+			else
+				ASSERT_STREQ(env.subtest_state->log_buf, "", "expected no output");
+			test__end_subtest();
+		}
+	}
+}