1 files changed, 97 insertions, 0 deletions
diff --git a/tools/testing/selftests/mm/map_hugetlb.c b/tools/testing/selftests/mm/map_hugetlb.c
new file mode 100644
index 0000000000..193281560b
--- /dev/null
+++ b/tools/testing/selftests/mm/map_hugetlb.c
@@ -0,0 +1,97 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Example of using hugepage memory in a user application using the mmap
+ * system call with MAP_HUGETLB flag.  Before running this program make
+ * sure the administrator has allocated enough default sized huge pages
+ * to cover the 256 MB allocation.
+ *
+ * For ia64 architecture, Linux kernel reserves Region number 4 for hugepages.
+ * That means the addresses starting with 0x800000... will need to be
+ * specified.  Specifying a fixed address is not required on ppc64, i386
+ * or x86_64.
+ */
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <fcntl.h>
+
+#define LENGTH (256UL*1024*1024)
+#define PROTECTION (PROT_READ | PROT_WRITE)
+
+/* Only ia64 requires this */
+#ifdef __ia64__
+#define ADDR (void *)(0x8000000000000000UL)
+#define FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB | MAP_FIXED)
+#else
+#define ADDR (void *)(0x0UL)
+#define FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB)
+#endif
+
+static void check_bytes(char *addr)
+{
+	printf("First hex is %x\n", *((unsigned int *)addr));
+}
+
+static void write_bytes(char *addr, size_t length)
+{
+	unsigned long i;
+
+	for (i = 0; i < length; i++)
+		*(addr + i) = (char)i;
+}
+
+static int read_bytes(char *addr, size_t length)
+{
+	unsigned long i;
+
+	check_bytes(addr);
+	for (i = 0; i < length; i++)
+		if (*(addr + i) != (char)i) {
+			printf("Mismatch at %lu\n", i);
+			return 1;
+		}
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	void *addr;
+	int ret;
+	size_t length = LENGTH;
+	int flags = FLAGS;
+	int shift = 0;
+
+	if (argc > 1)
+		length = atol(argv[1]) << 20;
+	if (argc > 2) {
+		shift = atoi(argv[2]);
+		if (shift)
+			flags |= (shift & MAP_HUGE_MASK) << MAP_HUGE_SHIFT;
+	}
+
+	if (shift)
+		printf("%u kB hugepages\n", 1 << (shift - 10));
+	else
+		printf("Default size hugepages\n");
+	printf("Mapping %lu Mbytes\n", (unsigned long)length >> 20);
+
+	addr = mmap(ADDR, length, PROTECTION, flags, -1, 0);
+	if (addr == MAP_FAILED) {
+		perror("mmap");
+		exit(1);
+	}
+
+	printf("Returned address is %p\n", addr);
+	check_bytes(addr);
+	write_bytes(addr, length);
+	ret = read_bytes(addr, length);
+
+	/* munmap() length of MAP_HUGETLB memory must be hugepage aligned */
+	if (munmap(addr, length)) {
+		perror("munmap");
+		exit(1);
+	}
+
+	return ret;
+}