1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * A test case of using hugepage memory in a user application using the
4 * mmap system call with MAP_HUGETLB flag. Before running this program
5 * make sure the administrator has allocated enough default sized huge
6 * pages to cover the 2 MB allocation.
7 */
8 #include <stdlib.h>
9 #include <stdio.h>
10 #include <unistd.h>
11 #include <sys/mman.h>
12 #include <fcntl.h>
13
14 #define MAP_LENGTH (2UL * 1024 * 1024)
15
16 #define PAGE_SIZE 4096
17
18 #define PAGE_COMPOUND_HEAD (1UL << 15)
19 #define PAGE_COMPOUND_TAIL (1UL << 16)
20 #define PAGE_HUGE (1UL << 17)
21
22 #define HEAD_PAGE_FLAGS (PAGE_COMPOUND_HEAD | PAGE_HUGE)
23 #define TAIL_PAGE_FLAGS (PAGE_COMPOUND_TAIL | PAGE_HUGE)
24
25 #define PM_PFRAME_BITS 55
26 #define PM_PFRAME_MASK ~((1UL << PM_PFRAME_BITS) - 1)
27
28 /*
29 * For ia64 architecture, Linux kernel reserves Region number 4 for hugepages.
30 * That means the addresses starting with 0x800000... will need to be
31 * specified. Specifying a fixed address is not required on ppc64, i386
32 * or x86_64.
33 */
34 #ifdef __ia64__
35 #define MAP_ADDR (void *)(0x8000000000000000UL)
36 #define MAP_FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB | MAP_FIXED)
37 #else
38 #define MAP_ADDR NULL
39 #define MAP_FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB)
40 #endif
41
write_bytes(char * addr,size_t length)42 static void write_bytes(char *addr, size_t length)
43 {
44 unsigned long i;
45
46 for (i = 0; i < length; i++)
47 *(addr + i) = (char)i;
48 }
49
virt_to_pfn(void * addr)50 static unsigned long virt_to_pfn(void *addr)
51 {
52 int fd;
53 unsigned long pagemap;
54
55 fd = open("/proc/self/pagemap", O_RDONLY);
56 if (fd < 0)
57 return -1UL;
58
59 lseek(fd, (unsigned long)addr / PAGE_SIZE * sizeof(pagemap), SEEK_SET);
60 read(fd, &pagemap, sizeof(pagemap));
61 close(fd);
62
63 return pagemap & ~PM_PFRAME_MASK;
64 }
65
check_page_flags(unsigned long pfn)66 static int check_page_flags(unsigned long pfn)
67 {
68 int fd, i;
69 unsigned long pageflags;
70
71 fd = open("/proc/kpageflags", O_RDONLY);
72 if (fd < 0)
73 return -1;
74
75 lseek(fd, pfn * sizeof(pageflags), SEEK_SET);
76
77 read(fd, &pageflags, sizeof(pageflags));
78 if ((pageflags & HEAD_PAGE_FLAGS) != HEAD_PAGE_FLAGS) {
79 close(fd);
80 printf("Head page flags (%lx) is invalid\n", pageflags);
81 return -1;
82 }
83
84 /*
85 * pages other than the first page must be tail and shouldn't be head;
86 * this also verifies kernel has correctly set the fake page_head to tail
87 * while hugetlb_free_vmemmap is enabled.
88 */
89 for (i = 1; i < MAP_LENGTH / PAGE_SIZE; i++) {
90 read(fd, &pageflags, sizeof(pageflags));
91 if ((pageflags & TAIL_PAGE_FLAGS) != TAIL_PAGE_FLAGS ||
92 (pageflags & HEAD_PAGE_FLAGS) == HEAD_PAGE_FLAGS) {
93 close(fd);
94 printf("Tail page flags (%lx) is invalid\n", pageflags);
95 return -1;
96 }
97 }
98
99 close(fd);
100
101 return 0;
102 }
103
main(int argc,char ** argv)104 int main(int argc, char **argv)
105 {
106 void *addr;
107 unsigned long pfn;
108
109 addr = mmap(MAP_ADDR, MAP_LENGTH, PROT_READ | PROT_WRITE, MAP_FLAGS, -1, 0);
110 if (addr == MAP_FAILED) {
111 perror("mmap");
112 exit(1);
113 }
114
115 /* Trigger allocation of HugeTLB page. */
116 write_bytes(addr, MAP_LENGTH);
117
118 pfn = virt_to_pfn(addr);
119 if (pfn == -1UL) {
120 munmap(addr, MAP_LENGTH);
121 perror("virt_to_pfn");
122 exit(1);
123 }
124
125 printf("Returned address is %p whose pfn is %lx\n", addr, pfn);
126
127 if (check_page_flags(pfn) < 0) {
128 munmap(addr, MAP_LENGTH);
129 perror("check_page_flags");
130 exit(1);
131 }
132
133 /* munmap() length of MAP_HUGETLB memory must be hugepage aligned */
134 if (munmap(addr, MAP_LENGTH)) {
135 perror("munmap");
136 exit(1);
137 }
138
139 return 0;
140 }
141