1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * tools/testing/selftests/kvm/lib/elf.c 4 * 5 * Copyright (C) 2018, Google LLC. 6 */ 7 8 #include "test_util.h" 9 10 #include <bits/endian.h> 11 #include <linux/elf.h> 12 13 #include "kvm_util.h" 14 15 static void elfhdr_get(const char *filename, Elf64_Ehdr *hdrp) 16 { 17 off_t offset_rv; 18 19 /* Open the ELF file. */ 20 int fd; 21 fd = open(filename, O_RDONLY); 22 TEST_ASSERT(fd >= 0, "Failed to open ELF file,\n" 23 " filename: %s\n" 24 " rv: %i errno: %i", filename, fd, errno); 25 26 /* Read in and validate ELF Identification Record. 27 * The ELF Identification record is the first 16 (EI_NIDENT) bytes 28 * of the ELF header, which is at the beginning of the ELF file. 29 * For now it is only safe to read the first EI_NIDENT bytes. Once 30 * read and validated, the value of e_ehsize can be used to determine 31 * the real size of the ELF header. 32 */ 33 unsigned char ident[EI_NIDENT]; 34 test_read(fd, ident, sizeof(ident)); 35 TEST_ASSERT((ident[EI_MAG0] == ELFMAG0) && (ident[EI_MAG1] == ELFMAG1) 36 && (ident[EI_MAG2] == ELFMAG2) && (ident[EI_MAG3] == ELFMAG3), 37 "ELF MAGIC Mismatch,\n" 38 " filename: %s\n" 39 " ident[EI_MAG0 - EI_MAG3]: %02x %02x %02x %02x\n" 40 " Expected: %02x %02x %02x %02x", 41 filename, 42 ident[EI_MAG0], ident[EI_MAG1], ident[EI_MAG2], ident[EI_MAG3], 43 ELFMAG0, ELFMAG1, ELFMAG2, ELFMAG3); 44 TEST_ASSERT(ident[EI_CLASS] == ELFCLASS64, 45 "Current implementation only able to handle ELFCLASS64,\n" 46 " filename: %s\n" 47 " ident[EI_CLASS]: %02x\n" 48 " expected: %02x", 49 filename, 50 ident[EI_CLASS], ELFCLASS64); 51 TEST_ASSERT(((BYTE_ORDER == LITTLE_ENDIAN) 52 && (ident[EI_DATA] == ELFDATA2LSB)) 53 || ((BYTE_ORDER == BIG_ENDIAN) 54 && (ident[EI_DATA] == ELFDATA2MSB)), "Current " 55 "implementation only able to handle\n" 56 "cases where the host and ELF file endianness\n" 57 "is the same:\n" 58 " host BYTE_ORDER: %u\n" 59 " host LITTLE_ENDIAN: %u\n" 60 " host BIG_ENDIAN: %u\n" 61 " ident[EI_DATA]: %u\n" 62 " ELFDATA2LSB: %u\n" 63 " ELFDATA2MSB: %u", 64 BYTE_ORDER, LITTLE_ENDIAN, BIG_ENDIAN, 65 ident[EI_DATA], ELFDATA2LSB, ELFDATA2MSB); 66 TEST_ASSERT(ident[EI_VERSION] == EV_CURRENT, 67 "Current implementation only able to handle current " 68 "ELF version,\n" 69 " filename: %s\n" 70 " ident[EI_VERSION]: %02x\n" 71 " expected: %02x", 72 filename, ident[EI_VERSION], EV_CURRENT); 73 74 /* Read in the ELF header. 75 * With the ELF Identification portion of the ELF header 76 * validated, especially that the value at EI_VERSION is 77 * as expected, it is now safe to read the entire ELF header. 78 */ 79 offset_rv = lseek(fd, 0, SEEK_SET); 80 TEST_ASSERT(offset_rv == 0, "Seek to ELF header failed,\n" 81 " rv: %zi expected: %i", offset_rv, 0); 82 test_read(fd, hdrp, sizeof(*hdrp)); 83 TEST_ASSERT(hdrp->e_phentsize == sizeof(Elf64_Phdr), 84 "Unexpected physical header size,\n" 85 " hdrp->e_phentsize: %x\n" 86 " expected: %zx", 87 hdrp->e_phentsize, sizeof(Elf64_Phdr)); 88 TEST_ASSERT(hdrp->e_shentsize == sizeof(Elf64_Shdr), 89 "Unexpected section header size,\n" 90 " hdrp->e_shentsize: %x\n" 91 " expected: %zx", 92 hdrp->e_shentsize, sizeof(Elf64_Shdr)); 93 } 94 95 /* VM ELF Load 96 * 97 * Input Args: 98 * filename - Path to ELF file 99 * 100 * Output Args: None 101 * 102 * Input/Output Args: 103 * vm - Pointer to opaque type that describes the VM. 104 * 105 * Return: None, TEST_ASSERT failures for all error conditions 106 * 107 * Loads the program image of the ELF file specified by filename, 108 * into the virtual address space of the VM pointed to by vm. On entry 109 * the VM needs to not be using any of the virtual address space used 110 * by the image and it needs to have sufficient available physical pages, to 111 * back the virtual pages used to load the image. 112 */ 113 void kvm_vm_elf_load(struct kvm_vm *vm, const char *filename) 114 { 115 off_t offset, offset_rv; 116 Elf64_Ehdr hdr; 117 118 /* Open the ELF file. */ 119 int fd; 120 fd = open(filename, O_RDONLY); 121 TEST_ASSERT(fd >= 0, "Failed to open ELF file,\n" 122 " filename: %s\n" 123 " rv: %i errno: %i", filename, fd, errno); 124 125 /* Read in the ELF header. */ 126 elfhdr_get(filename, &hdr); 127 128 /* For each program header. 129 * The following ELF header members specify the location 130 * and size of the program headers: 131 * 132 * e_phoff - File offset to start of program headers 133 * e_phentsize - Size of each program header 134 * e_phnum - Number of program header entries 135 */ 136 for (unsigned int n1 = 0; n1 < hdr.e_phnum; n1++) { 137 /* Seek to the beginning of the program header. */ 138 offset = hdr.e_phoff + (n1 * hdr.e_phentsize); 139 offset_rv = lseek(fd, offset, SEEK_SET); 140 TEST_ASSERT(offset_rv == offset, 141 "Failed to seek to begining of program header %u,\n" 142 " filename: %s\n" 143 " rv: %jd errno: %i", 144 n1, filename, (intmax_t) offset_rv, errno); 145 146 /* Read in the program header. */ 147 Elf64_Phdr phdr; 148 test_read(fd, &phdr, sizeof(phdr)); 149 150 /* Skip if this header doesn't describe a loadable segment. */ 151 if (phdr.p_type != PT_LOAD) 152 continue; 153 154 /* Allocate memory for this segment within the VM. */ 155 TEST_ASSERT(phdr.p_memsz > 0, "Unexpected loadable segment " 156 "memsize of 0,\n" 157 " phdr index: %u p_memsz: 0x%" PRIx64, 158 n1, (uint64_t) phdr.p_memsz); 159 vm_vaddr_t seg_vstart = align_down(phdr.p_vaddr, vm->page_size); 160 vm_vaddr_t seg_vend = phdr.p_vaddr + phdr.p_memsz - 1; 161 seg_vend |= vm->page_size - 1; 162 size_t seg_size = seg_vend - seg_vstart + 1; 163 164 vm_vaddr_t vaddr = vm_vaddr_alloc(vm, seg_size, seg_vstart); 165 TEST_ASSERT(vaddr == seg_vstart, "Unable to allocate " 166 "virtual memory for segment at requested min addr,\n" 167 " segment idx: %u\n" 168 " seg_vstart: 0x%lx\n" 169 " vaddr: 0x%lx", 170 n1, seg_vstart, vaddr); 171 memset(addr_gva2hva(vm, vaddr), 0, seg_size); 172 /* TODO(lhuemill): Set permissions of each memory segment 173 * based on the least-significant 3 bits of phdr.p_flags. 174 */ 175 176 /* Load portion of initial state that is contained within 177 * the ELF file. 178 */ 179 if (phdr.p_filesz) { 180 offset_rv = lseek(fd, phdr.p_offset, SEEK_SET); 181 TEST_ASSERT(offset_rv == phdr.p_offset, 182 "Seek to program segment offset failed,\n" 183 " program header idx: %u errno: %i\n" 184 " offset_rv: 0x%jx\n" 185 " expected: 0x%jx\n", 186 n1, errno, (intmax_t) offset_rv, 187 (intmax_t) phdr.p_offset); 188 test_read(fd, addr_gva2hva(vm, phdr.p_vaddr), 189 phdr.p_filesz); 190 } 191 } 192 } 193