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