[PATCH] selftests/vm: Add test to validate mirror functionality with mremap

[Anshuman Khandual]

This adds a test to validate mirror functionality with mremap()
system call on shared anon mappings.

Suggested-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Signed-off-by: Anshuman Khandual <khandual@xxxxxxxxxxxxxxxxxx>
---
 tools/testing/selftests/vm/Makefile                |  1 +
 .../selftests/vm/mremap_mirror_shared_anon.c       | 54 ++++++++++++++++++++++
 2 files changed, 55 insertions(+)
 create mode 100644 tools/testing/selftests/vm/mremap_mirror_shared_anon.c

diff --git a/tools/testing/selftests/vm/Makefile b/tools/testing/selftests/vm/Makefile
index cbb29e4..11657ff5 100644
--- a/tools/testing/selftests/vm/Makefile
+++ b/tools/testing/selftests/vm/Makefile
@@ -17,6 +17,7 @@ TEST_GEN_FILES += transhuge-stress
 TEST_GEN_FILES += userfaultfd
 TEST_GEN_FILES += mlock-random-test
 TEST_GEN_FILES += virtual_address_range
+TEST_GEN_FILES += mremap_mirror_shared_anon
 
 TEST_PROGS := run_vmtests
 
diff --git a/tools/testing/selftests/vm/mremap_mirror_shared_anon.c b/tools/testing/selftests/vm/mremap_mirror_shared_anon.c
new file mode 100644
index 0000000..b0adbb2
--- /dev/null
+++ b/tools/testing/selftests/vm/mremap_mirror_shared_anon.c
@@ -0,0 +1,54 @@
+/*
+ * Test to verify mirror functionality with mremap() system
+ * call for shared anon mappings.
+ *
+ * Copyright (C) 2017 Anshuman Khandual, IBM Corporation
+ *
+ * Licensed under GPL V2
+ */
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/mman.h>
+#include <sys/time.h>
+
+#define PATTERN		0xbe
+#define ALLOC_SIZE	0x10000UL /* Works for 64K and 4K pages */
+
+int test_mirror(char *old, char *new, unsigned long size)
+{
+	unsigned long i;
+
+	for (i = 0; i < size; i++) {
+		if (new[i] != old[i]) {
+			printf("Mismatch at new[%lu] expected "
+				"%d received %d\n", i, old[i], new[i]);
+			return 1;
+		}
+	}
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	char *ptr, *mirror_ptr;
+
+	ptr = mmap(NULL, ALLOC_SIZE, PROT_READ | PROT_WRITE,
+			MAP_SHARED | MAP_ANONYMOUS, -1, 0);
+	if (ptr == MAP_FAILED) {
+		perror("map() failed");
+		return -1;
+	}
+	memset(ptr, PATTERN, ALLOC_SIZE);
+
+	mirror_ptr =  (char *) mremap(ptr, 0, ALLOC_SIZE, 1);
+	if (mirror_ptr == MAP_FAILED) {
+		perror("mremap() failed");
+		return -1;
+	}
+
+	if (test_mirror(ptr, mirror_ptr, ALLOC_SIZE))
+		return 1;
+	return 0;
+}
-- 
1.8.5.2