proc: selftests: test /proc/uptime

The only tests I could come up with for /proc/uptime are:
 - test that values increase monotonically for 1 second,
 - bounce around CPUs and test the same thing.

Avoid glibc like plague for affinity given patches like this:
https://marc.info/?l=linux-kernel&m=152130031912594&w=4

Link: http://lkml.kernel.org/r/20180317165235.GB3445@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

5 files changed, 202 insertions, 0 deletions

diff --git a/tools/testing/selftests/proc/.gitignore b/tools/testing/selftests/proc/.gitignore
index 5627df81ade9..6c16f77c722c 100644
--- a/tools/testing/selftests/proc/.gitignore
+++ b/tools/testing/selftests/proc/.gitignore
@@ -3,4 +3,6 @@
 /proc-self-map-files-002
 /proc-self-syscall
 /proc-self-wchan
+/proc-uptime-001
+/proc-uptime-002
 /read
diff --git a/tools/testing/selftests/proc/Makefile b/tools/testing/selftests/proc/Makefile
index 312a3989820c..dbb87e56264c 100644
--- a/tools/testing/selftests/proc/Makefile
+++ b/tools/testing/selftests/proc/Makefile
@@ -6,6 +6,8 @@ TEST_GEN_PROGS += proc-self-map-files-001
 TEST_GEN_PROGS += proc-self-map-files-002
 TEST_GEN_PROGS += proc-self-syscall
 TEST_GEN_PROGS += proc-self-wchan
+TEST_GEN_PROGS += proc-uptime-001
+TEST_GEN_PROGS += proc-uptime-002
 TEST_GEN_PROGS += read
 
 include ../lib.mk
diff --git a/tools/testing/selftests/proc/proc-uptime-001.c b/tools/testing/selftests/proc/proc-uptime-001.c
new file mode 100644
index 000000000000..303f26092306
--- /dev/null
+++ b/tools/testing/selftests/proc/proc-uptime-001.c
@@ -0,0 +1,45 @@
+/*
+ * 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 values in /proc/uptime increment monotonically.
+#undef NDEBUG
+#include <assert.h>
+#include <stdint.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#include "proc-uptime.h"
+
+int main(void)
+{
+        uint64_t start, u0, u1, i0, i1;
+        int fd;
+
+        fd = open("/proc/uptime", O_RDONLY);
+        assert(fd >= 0);
+
+        proc_uptime(fd, &u0, &i0);
+        start = u0;
+        do {
+                proc_uptime(fd, &u1, &i1);
+                assert(u1 >= u0);
+                assert(i1 >= i0);
+                u0 = u1;
+                i0 = i1;
+        } while (u1 - start < 100);
+
+        return 0;
+}
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 000000000000..0cb79e1f1674
--- /dev/null
+++ b/tools/testing/selftests/proc/proc-uptime-002.c
@@ -0,0 +1,79 @@
+/*
+ * 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 values in /proc/uptime increment monotonically
+// while shifting across CPUs.
+#define _GNU_SOURCE
+#undef NDEBUG
+#include <assert.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)
+{
+        unsigned int len;
+        unsigned long *m;
+        unsigned int cpu;
+        uint64_t u0, u1, i0, i1;
+        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) == -EINVAL);
+
+        fd = open("/proc/uptime", O_RDONLY);
+        assert(fd >= 0);
+
+        proc_uptime(fd, &u0, &i0);
+        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);
+
+                proc_uptime(fd, &u1, &i1);
+                assert(u1 >= u0);
+                assert(i1 >= i0);
+                u0 = u1;
+                i0 = i1;
+        }
+
+        return 0;
+}
diff --git a/tools/testing/selftests/proc/proc-uptime.h b/tools/testing/selftests/proc/proc-uptime.h
new file mode 100644
index 000000000000..d584419f50a7
--- /dev/null
+++ b/tools/testing/selftests/proc/proc-uptime.h
@@ -0,0 +1,74 @@
+/*
+ * 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.
+ */
+#undef NDEBUG
+#include <assert.h>
+#include <errno.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+static unsigned long long xstrtoull(const char *p, char **end)
+{
+        if (*p == '0') {
+                *end = (char *)p + 1;
+                return 0;
+        } else if ('1' <= *p && *p <= '9') {
+                unsigned long long val;
+
+                errno = 0;
+                val = strtoull(p, end, 10);
+                assert(errno == 0);
+                return val;
+        } else
+                assert(0);
+}
+
+static void proc_uptime(int fd, uint64_t *uptime, uint64_t *idle)
+{
+        uint64_t val1, val2;
+        char buf[64], *p;
+        ssize_t rv;
+
+        /* save "p < end" checks */
+        memset(buf, 0, sizeof(buf));
+        rv = pread(fd, buf, sizeof(buf), 0);
+        assert(0 <= rv && rv <= sizeof(buf));
+        buf[sizeof(buf) - 1] = '\0';
+
+        p = buf;
+
+        val1 = xstrtoull(p, &p);
+        assert(p[0] == '.');
+        assert('0' <= p[1] && p[1] <= '9');
+        assert('0' <= p[2] && p[2] <= '9');
+        assert(p[3] == ' ');
+
+        val2 = (p[1] - '0') * 10 + p[2] - '0';
+        *uptime = val1 * 100 + val2;
+
+        p += 4;
+
+        val1 = xstrtoull(p, &p);
+        assert(p[0] == '.');
+        assert('0' <= p[1] && p[1] <= '9');
+        assert('0' <= p[2] && p[2] <= '9');
+        assert(p[3] == '\n');
+
+        val2 = (p[1] - '0') * 10 + p[2] - '0';
+        *idle = val1 * 100 + val2;
+
+        assert(p + 4 == buf + rv);
+}