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1// SPDX-License-Identifier: GPL-2.02/*3 * Example of using hugepage memory in a user application using the mmap4 * system call with MAP_HUGETLB flag. Before running this program make5 * sure the administrator has allocated enough default sized huge pages6 * to cover the 256 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#include "../kselftest.h"15 16#define LENGTH (256UL*1024*1024)17#define PROTECTION (PROT_READ | PROT_WRITE)18 19static void check_bytes(char *addr)20{21 ksft_print_msg("First hex is %x\n", *((unsigned int *)addr));22}23 24static void write_bytes(char *addr, size_t length)25{26 unsigned long i;27 28 for (i = 0; i < length; i++)29 *(addr + i) = (char)i;30}31 32static void read_bytes(char *addr, size_t length)33{34 unsigned long i;35 36 check_bytes(addr);37 for (i = 0; i < length; i++)38 if (*(addr + i) != (char)i)39 ksft_exit_fail_msg("Mismatch at %lu\n", i);40 41 ksft_test_result_pass("Read correct data\n");42}43 44int main(int argc, char **argv)45{46 void *addr;47 size_t hugepage_size;48 size_t length = LENGTH;49 int flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB;50 int shift = 0;51 52 hugepage_size = default_huge_page_size();53 /* munmap with fail if the length is not page aligned */54 if (hugepage_size > length)55 length = hugepage_size;56 57 ksft_print_header();58 ksft_set_plan(1);59 60 if (argc > 1)61 length = atol(argv[1]) << 20;62 if (argc > 2) {63 shift = atoi(argv[2]);64 if (shift)65 flags |= (shift & MAP_HUGE_MASK) << MAP_HUGE_SHIFT;66 }67 68 if (shift)69 ksft_print_msg("%u kB hugepages\n", 1 << (shift - 10));70 else71 ksft_print_msg("Default size hugepages\n");72 ksft_print_msg("Mapping %lu Mbytes\n", (unsigned long)length >> 20);73 74 addr = mmap(NULL, length, PROTECTION, flags, -1, 0);75 if (addr == MAP_FAILED)76 ksft_exit_fail_msg("mmap: %s\n", strerror(errno));77 78 ksft_print_msg("Returned address is %p\n", addr);79 check_bytes(addr);80 write_bytes(addr, length);81 read_bytes(addr, length);82 83 /* munmap() length of MAP_HUGETLB memory must be hugepage aligned */84 if (munmap(addr, length))85 ksft_exit_fail_msg("munmap: %s\n", strerror(errno));86 87 ksft_finished();88}89