1 files changed, 92 insertions, 0 deletions
diff --git a/tools/testing/selftests/proc/proc-uptime-002.c b/tools/testing/selftests/proc/proc-uptime-002.c
new file mode 100644
index 0000000000..ae453daa96
--- /dev/null
+++ b/tools/testing/selftests/proc/proc-uptime-002.c
@@ -0,0 +1,92 @@
+/*
+ * Copyright © 2018 Alexey Dobriyan <adobriyan@gmail.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+// Test that boottime value in /proc/uptime and CLOCK_BOOTTIME increment
+// monotonically while shifting across CPUs. We don't test idle time
+// monotonicity due to broken iowait task counting, cf: comment above
+// get_cpu_idle_time_us()
+#undef NDEBUG
+#include <assert.h>
+#include <errno.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <stdint.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#include "proc-uptime.h"
+
+static inline int sys_sched_getaffinity(pid_t pid, unsigned int len, unsigned long *m)
+{
+	return syscall(SYS_sched_getaffinity, pid, len, m);
+}
+
+static inline int sys_sched_setaffinity(pid_t pid, unsigned int len, unsigned long *m)
+{
+	return syscall(SYS_sched_setaffinity, pid, len, m);
+}
+
+int main(void)
+{
+	uint64_t u0, u1, c0, c1;
+	unsigned int len;
+	unsigned long *m;
+	unsigned int cpu;
+	int fd;
+
+	/* find out "nr_cpu_ids" */
+	m = NULL;
+	len = 0;
+	do {
+		len += sizeof(unsigned long);
+		free(m);
+		m = malloc(len);
+	} while (sys_sched_getaffinity(0, len, m) == -1 && errno == EINVAL);
+
+	fd = open("/proc/uptime", O_RDONLY);
+	assert(fd >= 0);
+
+	u0 = proc_uptime(fd);
+	c0 = clock_boottime();
+
+	for (cpu = 0; cpu < len * 8; cpu++) {
+		memset(m, 0, len);
+		m[cpu / (8 * sizeof(unsigned long))] |= 1UL << (cpu % (8 * sizeof(unsigned long)));
+
+		/* CPU might not exist, ignore error */
+		sys_sched_setaffinity(0, len, m);
+
+		u1 = proc_uptime(fd);
+		c1 = clock_boottime();
+
+		/* Is /proc/uptime monotonic ? */
+		assert(u1 >= u0);
+
+		/* Is CLOCK_BOOTTIME monotonic ? */
+		assert(c1 >= c0);
+
+		/* Is CLOCK_BOOTTIME VS /proc/uptime monotonic ? */
+		assert(c0 >= u0);
+
+		u0 = u1;
+		c0 = c1;
+	}
+
+	return 0;
+}