linux-kernel - [PATCH 6/6] selftests: vDSO: vdso_test

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Message-Id: <20260115-vdso-selftest-cleanups-v1-6-103e1ccbfdc3@linutronix.de>
Date: Thu, 15 Jan 2026 09:29:58 +0100
From: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
To: Andy Lutomirski <luto@...nel.org>, Thomas Gleixner <tglx@...nel.org>, 
 Vincenzo Frascino <vincenzo.frascino@....com>, 
 Shuah Khan <shuah@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org, 
 Thomas Weißschuh <thomas.weissschuh@...utronix.de>
Subject: [PATCH 6/6] selftests: vDSO: vdso_test_correctness: Add a test for
 time()

Extend the test to also cover the time() function.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
---
 .../testing/selftests/vDSO/vdso_test_correctness.c | 57 ++++++++++++++++++++++
 1 file changed, 57 insertions(+)

diff --git a/tools/testing/selftests/vDSO/vdso_test_correctness.c b/tools/testing/selftests/vDSO/vdso_test_correctness.c
index a94ab4d597b1..a3634e4980b5 100644
--- a/tools/testing/selftests/vDSO/vdso_test_correctness.c
+++ b/tools/testing/selftests/vDSO/vdso_test_correctness.c
@@ -55,6 +55,10 @@ typedef long (*vgtod_t)(struct timeval *tv, struct timezone *tz);
 
 vgtod_t vdso_gettimeofday;
 
+typedef time_t (*vtime_t)(__kernel_time_t *tloc);
+
+vtime_t vdso_time;
+
 typedef long (*getcpu_t)(unsigned *, unsigned *, void *);
 
 getcpu_t vgetcpu;
@@ -133,6 +137,10 @@ static void fill_function_pointers(void)
 	if (!vdso_gettimeofday)
 		printf("Warning: failed to find gettimeofday in vDSO\n");
 
+	vdso_time = (vtime_t)vdso_sym(version, name[2]);
+	if (!vdso_time)
+		printf("Warning: failed to find time in vDSO\n");
+
 }
 
 static long sys_getcpu(unsigned * cpu, unsigned * node,
@@ -156,6 +164,11 @@ static inline int sys_gettimeofday(struct timeval *tv, struct timezone *tz)
 	return syscall(__NR_gettimeofday, tv, tz);
 }
 
+static inline time_t sys_time(__kernel_time_t *tloc)
+{
+	return syscall(__NR_time, tloc);
+}
+
 static void test_getcpu(void)
 {
 	printf("[RUN]\tTesting getcpu...\n");
@@ -422,6 +435,49 @@ static void test_gettimeofday(void)
 	VDSO_CALL(vdso_gettimeofday, 2, &vdso, NULL);
 }
 
+static void test_time(void)
+{
+	__kernel_old_time_t start, end, vdso_ret, vdso_param;
+
+	if (!vdso_time)
+		return;
+
+	printf("[RUN]\tTesting time...\n");
+
+	if (sys_time(&start) < 0) {
+		printf("[FAIL]\tsys_time failed (%d)\n", errno);
+		nerrs++;
+		return;
+	}
+
+	vdso_ret = VDSO_CALL(vdso_time, 1, &vdso_param);
+	end = sys_time(NULL);
+
+	if (vdso_ret < 0 || end < 0) {
+		printf("[FAIL]\tvDSO returned %d, syscall errno=%d\n",
+		       (int)vdso_ret, errno);
+		nerrs++;
+		return;
+	}
+
+	printf("\t%lld %lld %lld\n",
+	       (long long)start,
+	       (long long)vdso_ret,
+	       (long long)end);
+
+	if (vdso_ret != vdso_param) {
+		printf("[FAIL]\tinconsistent return values: %lld %lld\n",
+		       (long long)vdso_ret, (long long)vdso_param);
+		nerrs++;
+		return;
+	}
+
+	if (!(start <= vdso_ret) || !(vdso_ret <= end)) {
+		printf("[FAIL]\tTimes are out of sequence\n");
+		nerrs++;
+	}
+}
+
 int main(int argc, char **argv)
 {
 	version = versions[VDSO_VERSION];
@@ -432,6 +488,7 @@ int main(int argc, char **argv)
 	test_clock_gettime();
 	test_clock_gettime64();
 	test_gettimeofday();
+	test_time();
 
 	/*
 	 * Test getcpu() last so that, if something goes wrong setting affinity,

-- 
2.52.0