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Subject[PATCH 4.14 13/45] selftests/x86: Add clock_gettime() tests to test_vdso
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Andy Lutomirski <luto@kernel.org>

commit 7c03e7035ac1cf2a6165754e4f3a49c2f1977838 upstream.

Now that the vDSO implementation of clock_gettime() is getting
reworked, add a selftest for it. This tests that its output is
consistent with the syscall version.

This is marked for stable to serve as a test for commit

715bd9d12f84 ("x86/vdso: Fix asm constraints on vDSO syscall fallbacks")

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/082399674de2619b2befd8c0dde49b260605b126.1538422295.git.luto@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
tools/testing/selftests/x86/test_vdso.c | 99 ++++++++++++++++++++++++++++++++
1 file changed, 99 insertions(+)

--- a/tools/testing/selftests/x86/test_vdso.c
+++ b/tools/testing/selftests/x86/test_vdso.c
@@ -17,6 +17,7 @@
#include <errno.h>
#include <sched.h>
#include <stdbool.h>
+#include <limits.h>

#ifndef SYS_getcpu
# ifdef __x86_64__
@@ -31,6 +32,10 @@

int nerrs = 0;

+typedef int (*vgettime_t)(clockid_t, struct timespec *);
+
+vgettime_t vdso_clock_gettime;
+
typedef long (*getcpu_t)(unsigned *, unsigned *, void *);

getcpu_t vgetcpu;
@@ -95,6 +100,10 @@ static void fill_function_pointers()
printf("Warning: failed to find getcpu in vDSO\n");

vgetcpu = (getcpu_t) vsyscall_getcpu();
+
+ vdso_clock_gettime = (vgettime_t)dlsym(vdso, "__vdso_clock_gettime");
+ if (!vdso_clock_gettime)
+ printf("Warning: failed to find clock_gettime in vDSO\n");
}

static long sys_getcpu(unsigned * cpu, unsigned * node,
@@ -103,6 +112,11 @@ static long sys_getcpu(unsigned * cpu, u
return syscall(__NR_getcpu, cpu, node, cache);
}

+static inline int sys_clock_gettime(clockid_t id, struct timespec *ts)
+{
+ return syscall(__NR_clock_gettime, id, ts);
+}
+
static void test_getcpu(void)
{
printf("[RUN]\tTesting getcpu...\n");
@@ -155,10 +169,95 @@ static void test_getcpu(void)
}
}

+static bool ts_leq(const struct timespec *a, const struct timespec *b)
+{
+ if (a->tv_sec != b->tv_sec)
+ return a->tv_sec < b->tv_sec;
+ else
+ return a->tv_nsec <= b->tv_nsec;
+}
+
+static char const * const clocknames[] = {
+ [0] = "CLOCK_REALTIME",
+ [1] = "CLOCK_MONOTONIC",
+ [2] = "CLOCK_PROCESS_CPUTIME_ID",
+ [3] = "CLOCK_THREAD_CPUTIME_ID",
+ [4] = "CLOCK_MONOTONIC_RAW",
+ [5] = "CLOCK_REALTIME_COARSE",
+ [6] = "CLOCK_MONOTONIC_COARSE",
+ [7] = "CLOCK_BOOTTIME",
+ [8] = "CLOCK_REALTIME_ALARM",
+ [9] = "CLOCK_BOOTTIME_ALARM",
+ [10] = "CLOCK_SGI_CYCLE",
+ [11] = "CLOCK_TAI",
+};
+
+static void test_one_clock_gettime(int clock, const char *name)
+{
+ struct timespec start, vdso, end;
+ int vdso_ret, end_ret;
+
+ printf("[RUN]\tTesting clock_gettime for clock %s (%d)...\n", name, clock);
+
+ if (sys_clock_gettime(clock, &start) < 0) {
+ if (errno == EINVAL) {
+ vdso_ret = vdso_clock_gettime(clock, &vdso);
+ if (vdso_ret == -EINVAL) {
+ printf("[OK]\tNo such clock.\n");
+ } else {
+ printf("[FAIL]\tNo such clock, but __vdso_clock_gettime returned %d\n", vdso_ret);
+ nerrs++;
+ }
+ } else {
+ printf("[WARN]\t clock_gettime(%d) syscall returned error %d\n", clock, errno);
+ }
+ return;
+ }
+
+ vdso_ret = vdso_clock_gettime(clock, &vdso);
+ end_ret = sys_clock_gettime(clock, &end);
+
+ if (vdso_ret != 0 || end_ret != 0) {
+ printf("[FAIL]\tvDSO returned %d, syscall errno=%d\n",
+ vdso_ret, errno);
+ nerrs++;
+ return;
+ }
+
+ printf("\t%llu.%09ld %llu.%09ld %llu.%09ld\n",
+ (unsigned long long)start.tv_sec, start.tv_nsec,
+ (unsigned long long)vdso.tv_sec, vdso.tv_nsec,
+ (unsigned long long)end.tv_sec, end.tv_nsec);
+
+ if (!ts_leq(&start, &vdso) || !ts_leq(&vdso, &end)) {
+ printf("[FAIL]\tTimes are out of sequence\n");
+ nerrs++;
+ }
+}
+
+static void test_clock_gettime(void)
+{
+ for (int clock = 0; clock < sizeof(clocknames) / sizeof(clocknames[0]);
+ clock++) {
+ test_one_clock_gettime(clock, clocknames[clock]);
+ }
+
+ /* Also test some invalid clock ids */
+ test_one_clock_gettime(-1, "invalid");
+ test_one_clock_gettime(INT_MIN, "invalid");
+ test_one_clock_gettime(INT_MAX, "invalid");
+}
+
int main(int argc, char **argv)
{
fill_function_pointers();

+ test_clock_gettime();
+
+ /*
+ * Test getcpu() last so that, if something goes wrong setting affinity,
+ * we still run the other tests.
+ */
test_getcpu();

return nerrs ? 1 : 0;

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