1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Example of using hugepage memory in a user application using the mmap
4 * system call with MAP_HUGETLB flag.  Before running this program make
5 * sure the administrator has allocated enough default sized huge pages
6 * to cover the 256 MB allocation.
7 *
8 * For ia64 architecture, Linux kernel reserves Region number 4 for hugepages.
9 * That means the addresses starting with 0x800000... will need to be
10 * specified.  Specifying a fixed address is not required on ppc64, i386
11 * or x86_64.
12 */
13#include <stdlib.h>
14#include <stdio.h>
15#include <unistd.h>
16#include <sys/mman.h>
17#include <fcntl.h>
18#include "vm_util.h"
19#include "../kselftest.h"
20
21#define LENGTH (256UL*1024*1024)
22#define PROTECTION (PROT_READ | PROT_WRITE)
23
24/* Only ia64 requires this */
25#ifdef __ia64__
26#define ADDR (void *)(0x8000000000000000UL)
27#define FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB | MAP_FIXED)
28#else
29#define ADDR (void *)(0x0UL)
30#define FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB)
31#endif
32
33static void check_bytes(char *addr)
34{
35	ksft_print_msg("First hex is %x\n", *((unsigned int *)addr));
36}
37
38static void write_bytes(char *addr, size_t length)
39{
40	unsigned long i;
41
42	for (i = 0; i < length; i++)
43		*(addr + i) = (char)i;
44}
45
46static void read_bytes(char *addr, size_t length)
47{
48	unsigned long i;
49
50	check_bytes(addr);
51	for (i = 0; i < length; i++)
52		if (*(addr + i) != (char)i)
53			ksft_exit_fail_msg("Mismatch at %lu\n", i);
54
55	ksft_test_result_pass("Read correct data\n");
56}
57
58int main(int argc, char **argv)
59{
60	void *addr;
61	size_t hugepage_size;
62	size_t length = LENGTH;
63	int flags = FLAGS;
64	int shift = 0;
65
66	hugepage_size = default_huge_page_size();
67	/* munmap with fail if the length is not page aligned */
68	if (hugepage_size > length)
69		length = hugepage_size;
70
71	ksft_print_header();
72	ksft_set_plan(1);
73
74	if (argc > 1)
75		length = atol(argv[1]) << 20;
76	if (argc > 2) {
77		shift = atoi(argv[2]);
78		if (shift)
79			flags |= (shift & MAP_HUGE_MASK) << MAP_HUGE_SHIFT;
80	}
81
82	if (shift)
83		ksft_print_msg("%u kB hugepages\n", 1 << (shift - 10));
84	else
85		ksft_print_msg("Default size hugepages\n");
86	ksft_print_msg("Mapping %lu Mbytes\n", (unsigned long)length >> 20);
87
88	addr = mmap(ADDR, length, PROTECTION, flags, -1, 0);
89	if (addr == MAP_FAILED)
90		ksft_exit_fail_msg("mmap: %s\n", strerror(errno));
91
92	ksft_print_msg("Returned address is %p\n", addr);
93	check_bytes(addr);
94	write_bytes(addr, length);
95	read_bytes(addr, length);
96
97	/* munmap() length of MAP_HUGETLB memory must be hugepage aligned */
98	if (munmap(addr, length))
99		ksft_exit_fail_msg("munmap: %s\n", strerror(errno));
100
101	ksft_finished();
102}
103