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
33 static void check_bytes(char *addr)
34 {
35 ksft_print_msg("First hex is %x\n", *((unsigned int *)addr));
36 }
37
38 static 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
46 static 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
58 int 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
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