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1// SPDX-License-Identifier: GPL-2.02/*3 * A test case of using hugepage memory in a user application using the4 * mmap system call with MAP_HUGETLB flag. Before running this program5 * make sure the administrator has allocated enough default sized huge6 * 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 5523#define PM_PFRAME_MASK ~((1UL << PM_PFRAME_BITS) - 1)24 25static size_t pagesize;26static size_t maplength;27 28static void write_bytes(char *addr, size_t length)29{30 unsigned long i;31 32 for (i = 0; i < length; i++)33 *(addr + i) = (char)i;34}35 36static unsigned long virt_to_pfn(void *addr)37{38 int fd;39 unsigned long pagemap;40 41 fd = open("/proc/self/pagemap", O_RDONLY);42 if (fd < 0)43 return -1UL;44 45 lseek(fd, (unsigned long)addr / pagesize * sizeof(pagemap), SEEK_SET);46 read(fd, &pagemap, sizeof(pagemap));47 close(fd);48 49 return pagemap & ~PM_PFRAME_MASK;50}51 52static int check_page_flags(unsigned long pfn)53{54 int fd, i;55 unsigned long pageflags;56 57 fd = open("/proc/kpageflags", O_RDONLY);58 if (fd < 0)59 return -1;60 61 lseek(fd, pfn * sizeof(pageflags), SEEK_SET);62 63 read(fd, &pageflags, sizeof(pageflags));64 if ((pageflags & HEAD_PAGE_FLAGS) != HEAD_PAGE_FLAGS) {65 close(fd);66 printf("Head page flags (%lx) is invalid\n", pageflags);67 return -1;68 }69 70 /*71 * pages other than the first page must be tail and shouldn't be head;72 * this also verifies kernel has correctly set the fake page_head to tail73 * while hugetlb_free_vmemmap is enabled.74 */75 for (i = 1; i < maplength / pagesize; i++) {76 read(fd, &pageflags, sizeof(pageflags));77 if ((pageflags & TAIL_PAGE_FLAGS) != TAIL_PAGE_FLAGS ||78 (pageflags & HEAD_PAGE_FLAGS) == HEAD_PAGE_FLAGS) {79 close(fd);80 printf("Tail page flags (%lx) is invalid\n", pageflags);81 return -1;82 }83 }84 85 close(fd);86 87 return 0;88}89 90int main(int argc, char **argv)91{92 void *addr;93 unsigned long pfn;94 95 pagesize = psize();96 maplength = default_huge_page_size();97 if (!maplength) {98 printf("Unable to determine huge page size\n");99 exit(1);100 }101 102 addr = mmap(NULL, maplength, PROT_READ | PROT_WRITE,103 MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB, -1, 0);104 if (addr == MAP_FAILED) {105 perror("mmap");106 exit(1);107 }108 109 /* Trigger allocation of HugeTLB page. */110 write_bytes(addr, maplength);111 112 pfn = virt_to_pfn(addr);113 if (pfn == -1UL) {114 munmap(addr, maplength);115 perror("virt_to_pfn");116 exit(1);117 }118 119 printf("Returned address is %p whose pfn is %lx\n", addr, pfn);120 121 if (check_page_flags(pfn) < 0) {122 munmap(addr, maplength);123 perror("check_page_flags");124 exit(1);125 }126 127 /* munmap() length of MAP_HUGETLB memory must be hugepage aligned */128 if (munmap(addr, maplength)) {129 perror("munmap");130 exit(1);131 }132 133 return 0;134}135