1 // SPDX-License-Identifier: GPL-2.0 1 // SPDX-License-Identifier: GPL-2.0
2 /* 2 /*
3 * hugepage-mmap: 3 * hugepage-mmap:
4 * 4 *
5 * Example of using huge page memory in a user 5 * Example of using huge page memory in a user application using the mmap
6 * system call. Before running this applicati 6 * system call. Before running this application, make sure that the
7 * administrator has mounted the hugetlbfs fil 7 * administrator has mounted the hugetlbfs filesystem (on some directory
8 * like /mnt) using the command mount -t huget 8 * like /mnt) using the command mount -t hugetlbfs nodev /mnt. In this
9 * example, the app is requesting memory of si 9 * example, the app is requesting memory of size 256MB that is backed by
10 * huge pages. 10 * huge pages.
11 * 11 *
12 * For the ia64 architecture, the Linux kernel 12 * For the ia64 architecture, the Linux kernel reserves Region number 4 for
13 * huge pages. That means that if one require 13 * huge pages. That means that if one requires a fixed address, a huge page
14 * aligned address starting with 0x800000... w 14 * aligned address starting with 0x800000... will be required. If a fixed
15 * address is not required, the kernel will se 15 * address is not required, the kernel will select an address in the proper
16 * range. 16 * range.
17 * Other architectures, such as ppc64, i386 or 17 * Other architectures, such as ppc64, i386 or x86_64 are not so constrained.
18 */ 18 */
19 #define _GNU_SOURCE 19 #define _GNU_SOURCE
20 #include <stdlib.h> 20 #include <stdlib.h>
21 #include <stdio.h> 21 #include <stdio.h>
22 #include <unistd.h> 22 #include <unistd.h>
23 #include <sys/mman.h> 23 #include <sys/mman.h>
24 #include <fcntl.h> 24 #include <fcntl.h>
25 #include "../kselftest.h" 25 #include "../kselftest.h"
26 26
27 #define LENGTH (256UL*1024*1024) 27 #define LENGTH (256UL*1024*1024)
28 #define PROTECTION (PROT_READ | PROT_WRITE) 28 #define PROTECTION (PROT_READ | PROT_WRITE)
29 29
30 /* Only ia64 requires this */ 30 /* Only ia64 requires this */
31 #ifdef __ia64__ 31 #ifdef __ia64__
32 #define ADDR (void *)(0x8000000000000000UL) 32 #define ADDR (void *)(0x8000000000000000UL)
33 #define FLAGS (MAP_SHARED | MAP_FIXED) 33 #define FLAGS (MAP_SHARED | MAP_FIXED)
34 #else 34 #else
35 #define ADDR (void *)(0x0UL) 35 #define ADDR (void *)(0x0UL)
36 #define FLAGS (MAP_SHARED) 36 #define FLAGS (MAP_SHARED)
37 #endif 37 #endif
38 38
39 static void check_bytes(char *addr) 39 static void check_bytes(char *addr)
40 { 40 {
41 ksft_print_msg("First hex is %x\n", *( 41 ksft_print_msg("First hex is %x\n", *((unsigned int *)addr));
42 } 42 }
43 43
44 static void write_bytes(char *addr) 44 static void write_bytes(char *addr)
45 { 45 {
46 unsigned long i; 46 unsigned long i;
47 47
48 for (i = 0; i < LENGTH; i++) 48 for (i = 0; i < LENGTH; i++)
49 *(addr + i) = (char)i; 49 *(addr + i) = (char)i;
50 } 50 }
51 51
52 static int read_bytes(char *addr) 52 static int read_bytes(char *addr)
53 { 53 {
54 unsigned long i; 54 unsigned long i;
55 55
56 check_bytes(addr); 56 check_bytes(addr);
57 for (i = 0; i < LENGTH; i++) 57 for (i = 0; i < LENGTH; i++)
58 if (*(addr + i) != (char)i) { 58 if (*(addr + i) != (char)i) {
59 ksft_print_msg("Error: 59 ksft_print_msg("Error: Mismatch at %lu\n", i);
60 return 1; 60 return 1;
61 } 61 }
62 return 0; 62 return 0;
63 } 63 }
64 64
65 int main(void) 65 int main(void)
66 { 66 {
67 void *addr; 67 void *addr;
68 int fd, ret; 68 int fd, ret;
69 69
70 ksft_print_header(); 70 ksft_print_header();
71 ksft_set_plan(1); 71 ksft_set_plan(1);
72 72
73 fd = memfd_create("hugepage-mmap", MFD 73 fd = memfd_create("hugepage-mmap", MFD_HUGETLB);
74 if (fd < 0) 74 if (fd < 0)
75 ksft_exit_fail_msg("memfd_crea 75 ksft_exit_fail_msg("memfd_create() failed: %s\n", strerror(errno));
76 76
77 addr = mmap(ADDR, LENGTH, PROTECTION, 77 addr = mmap(ADDR, LENGTH, PROTECTION, FLAGS, fd, 0);
78 if (addr == MAP_FAILED) { 78 if (addr == MAP_FAILED) {
79 close(fd); 79 close(fd);
80 ksft_exit_fail_msg("mmap(): %s 80 ksft_exit_fail_msg("mmap(): %s\n", strerror(errno));
81 } 81 }
82 82
83 ksft_print_msg("Returned address is %p 83 ksft_print_msg("Returned address is %p\n", addr);
84 check_bytes(addr); 84 check_bytes(addr);
85 write_bytes(addr); 85 write_bytes(addr);
86 ret = read_bytes(addr); 86 ret = read_bytes(addr);
87 87
88 munmap(addr, LENGTH); 88 munmap(addr, LENGTH);
89 close(fd); 89 close(fd);
90 90
91 ksft_test_result(!ret, "Read same data 91 ksft_test_result(!ret, "Read same data\n");
92 92
93 ksft_exit(!ret); 93 ksft_exit(!ret);
94 } 94 }
95 95
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.