s390:zdtm: Add test for tasks > 4TB

If the kernel contains patch ee71d16d22 ("s390/mm: make TASK_SIZE
independent from the number of page table levels") we are able
to checkpoint tasks > 4TB.

Add a testcase to verify this.
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

test/zdtm/static/Makefile

@@ -171,6 +171,7 @@ TST_NOFILE	:=				\
 		macvlan			\
 		cr_veth				\
 		sock_peercred			\
+		s390x_mmap_high			\
 #		jobctl00			\
 
 ifneq ($(SRCARCH),arm)

test/zdtm/static/s390x_mmap_high.c

+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+#include "zdtmtst.h"
+
+#define TASK_SIZE_LEVEL_4	0x20000000000000UL	/* 8 PB */
+#define MAP_SIZE	0x1000
+#define VAL		0x77
+
+const char *test_doc	= "Verify that tasks > 4TB can be checkpointed";
+const char *test_author	= "Michael Holzheu <holzheu@linux.vnet.ibm.com>";
+
+/*
+ * Map memory at the very end of the 8 PB address space
+ */
+int main(int argc, char **argv)
+{
+	void *addr = (void *) TASK_SIZE_LEVEL_4 - MAP_SIZE;
+	char *buf;
+	int i;
+
+
+	test_init(argc, argv);
+
+	/*
+	 * Skip test if kernel does not have the following fix:
+	 *
+	 * ee71d16d22 ("s390/mm: make TASK_SIZE independent from the number
+	 *              of page table levels")
+	 */
+	if (munmap(addr, MAP_SIZE) == -1) {
+		test_daemon();
+		test_waitsig();
+		skip("Detected kernel without 4 level TASK_SIZE fix");
+		pass();
+		return 0;
+	}
+
+	/* Map memory at the very end of the 8 PB address space */
+	buf = mmap(addr, MAP_SIZE, PROT_WRITE | PROT_READ,
+			MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, -1, 0);
+	if (buf == MAP_FAILED) {
+		pr_perror("Could not create mapping");
+		exit(1);
+	}
+	/* Initialize buffer with data */
+	memset(buf, VAL, MAP_SIZE);
+
+	test_daemon();
+	test_waitsig();
+
+	/* Verify that we restored the data correctly */
+	for (i = 0; i < MAP_SIZE; i++) {
+		if (buf[i] == VAL)
+			continue;
+		fail("%d: %d != %d\n", i, buf[i], VAL);
+		goto out;
+	}
+	pass();
+out:
+	return 0;
+}

test/zdtm/static/s390x_mmap_high.desc

+{'arch': 's390x'}