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 | #include "vm_util.h" |
14 | |
15 | #define PAGE_COMPOUND_HEAD (1UL << 15) |
16 | #define PAGE_COMPOUND_TAIL (1UL << 16) |
17 | #define PAGE_HUGE (1UL << 17) |
18 | |
19 | #define HEAD_PAGE_FLAGS (PAGE_COMPOUND_HEAD | PAGE_HUGE) |
20 | #define TAIL_PAGE_FLAGS (PAGE_COMPOUND_TAIL | PAGE_HUGE) |
21 | |
22 | #define PM_PFRAME_BITS 55 |
23 | #define PM_PFRAME_MASK ~((1UL << PM_PFRAME_BITS) - 1) |
24 | |
25 | /* |
26 | * For ia64 architecture, Linux kernel reserves Region number 4 for hugepages. |
27 | * That means the addresses starting with 0x800000... will need to be |
28 | * specified. Specifying a fixed address is not required on ppc64, i386 |
29 | * or x86_64. |
30 | */ |
31 | #ifdef __ia64__ |
32 | #define MAP_ADDR (void *)(0x8000000000000000UL) |
33 | #define MAP_FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB | MAP_FIXED) |
34 | #else |
35 | #define MAP_ADDR NULL |
36 | #define MAP_FLAGS (MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB) |
37 | #endif |
38 | |
39 | static size_t pagesize; |
40 | static size_t maplength; |
41 | |
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 | |
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 / pagesize * sizeof(pagemap), SEEK_SET); |
60 | read(fd, &pagemap, sizeof(pagemap)); |
61 | close(fd); |
62 | |
63 | return pagemap & ~PM_PFRAME_MASK; |
64 | } |
65 | |
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 < maplength / pagesize; 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 | |
104 | int main(int argc, char **argv) |
105 | { |
106 | void *addr; |
107 | unsigned long pfn; |
108 | |
109 | pagesize = psize(); |
110 | maplength = default_huge_page_size(); |
111 | if (!maplength) { |
112 | printf("Unable to determine huge page size\n" ); |
113 | exit(1); |
114 | } |
115 | |
116 | addr = mmap(MAP_ADDR, maplength, PROT_READ | PROT_WRITE, MAP_FLAGS, -1, 0); |
117 | if (addr == MAP_FAILED) { |
118 | perror("mmap" ); |
119 | exit(1); |
120 | } |
121 | |
122 | /* Trigger allocation of HugeTLB page. */ |
123 | write_bytes(addr, maplength); |
124 | |
125 | pfn = virt_to_pfn(addr); |
126 | if (pfn == -1UL) { |
127 | munmap(addr, maplength); |
128 | perror("virt_to_pfn" ); |
129 | exit(1); |
130 | } |
131 | |
132 | printf("Returned address is %p whose pfn is %lx\n" , addr, pfn); |
133 | |
134 | if (check_page_flags(pfn) < 0) { |
135 | munmap(addr, maplength); |
136 | perror("check_page_flags" ); |
137 | exit(1); |
138 | } |
139 | |
140 | /* munmap() length of MAP_HUGETLB memory must be hugepage aligned */ |
141 | if (munmap(addr, maplength)) { |
142 | perror("munmap" ); |
143 | exit(1); |
144 | } |
145 | |
146 | return 0; |
147 | } |
148 | |