| 1 | /* |
| 2 | * Post-process a vdso elf image for inclusion into qemu. |
| 3 | * |
| 4 | * Copyright 2023 Linaro, Ltd. |
| 5 | * |
| 6 | * SPDX-License-Identifier: GPL-2.0-or-later |
| 7 | */ |
| 8 | |
| 9 | #include <stdlib.h> |
| 10 | #include <stdbool.h> |
| 11 | #include <stdint.h> |
| 12 | #include <stdio.h> |
| 13 | #include <string.h> |
| 14 | #include <errno.h> |
| 15 | #include <endian.h> |
| 16 | #include <unistd.h> |
| 17 | #include "elf.h" |
| 18 | |
| 19 | |
| 20 | #define bswap_(p) _Generic(*(p), \ |
| 21 | uint16_t: __builtin_bswap16, \ |
| 22 | uint32_t: __builtin_bswap32, \ |
| 23 | uint64_t: __builtin_bswap64, \ |
| 24 | int16_t: __builtin_bswap16, \ |
| 25 | int32_t: __builtin_bswap32, \ |
| 26 | int64_t: __builtin_bswap64) |
| 27 | #define bswaps(p) (*(p) = bswap_(p)(*(p))) |
| 28 | |
| 29 | static void output_reloc(FILE *outf, void *buf, void *loc) |
| 30 | { |
| 31 | fprintf(outf, " 0x%08tx,\n", loc - buf); |
| 32 | } |
| 33 | |
| 34 | static const char *sigreturn_sym; |
| 35 | static const char *rt_sigreturn_sym; |
| 36 | |
| 37 | static unsigned sigreturn_addr; |
| 38 | static unsigned rt_sigreturn_addr; |
| 39 | static unsigned sigreturn_region_start_addr; |
| 40 | static unsigned sigreturn_region_end_addr; |
| 41 | |
| 42 | #define N 32 |
| 43 | #define elfN(x) elf32_##x |
| 44 | #define ElfN(x) Elf32_##x |
| 45 | #include "gen-vdso-elfn.c.inc" |
| 46 | #undef N |
| 47 | #undef elfN |
| 48 | #undef ElfN |
| 49 | |
| 50 | #define N 64 |
| 51 | #define elfN(x) elf64_##x |
| 52 | #define ElfN(x) Elf64_##x |
| 53 | #include "gen-vdso-elfn.c.inc" |
| 54 | #undef N |
| 55 | #undef elfN |
| 56 | #undef ElfN |
| 57 | |
| 58 | |
| 59 | int main(int argc, char **argv) |
| 60 | { |
| 61 | FILE *inf = NULL, *outf = NULL; |
| 62 | long total_len; |
| 63 | const char *prefix = "vdso"; |
| 64 | const char *inf_name; |
| 65 | const char *outf_name = NULL; |
| 66 | unsigned char *buf = NULL; |
| 67 | bool need_bswap; |
| 68 | int ret = EXIT_FAILURE; |
| 69 | |
| 70 | while (1) { |
| 71 | int opt = getopt(argc, argv, "o:p:r:s:"); |
| 72 | if (opt < 0) { |
| 73 | break; |
| 74 | } |
| 75 | switch (opt) { |
| 76 | case 'o': |
| 77 | outf_name = optarg; |
| 78 | break; |
| 79 | case 'p': |
| 80 | prefix = optarg; |
| 81 | break; |
| 82 | case 'r': |
| 83 | rt_sigreturn_sym = optarg; |
| 84 | break; |
| 85 | case 's': |
| 86 | sigreturn_sym = optarg; |
| 87 | break; |
| 88 | default: |
| 89 | usage: |
| 90 | fprintf(stderr, "usage: [-p prefix] [-r rt-sigreturn-name] " |
| 91 | "[-s sigreturn-name] -o output-file input-file\n"); |
| 92 | return EXIT_FAILURE; |
| 93 | } |
| 94 | } |
| 95 | |
| 96 | if (optind >= argc || outf_name == NULL) { |
| 97 | goto usage; |
| 98 | } |
| 99 | inf_name = argv[optind]; |
| 100 | |
| 101 | /* |
| 102 | * Open the input and output files. |
| 103 | */ |
| 104 | inf = fopen(inf_name, "rb"); |
| 105 | if (inf == NULL) { |
| 106 | goto perror_inf; |
| 107 | } |
| 108 | outf = fopen(outf_name, "w"); |
| 109 | if (outf == NULL) { |
| 110 | goto perror_outf; |
| 111 | } |
| 112 | |
| 113 | /* |
| 114 | * Read the input file into a buffer. |
| 115 | * We expect the vdso to be small, on the order of one page, |
| 116 | * therefore we do not expect a partial read. |
| 117 | */ |
| 118 | if (fseek(inf, 0, SEEK_END) < 0) { |
| 119 | goto perror_inf; |
| 120 | } |
| 121 | total_len = ftell(inf); |
| 122 | if (total_len < 0) { |
| 123 | goto perror_inf; |
| 124 | } |
| 125 | if (fseek(inf, 0, SEEK_SET) < 0) { |
| 126 | goto perror_inf; |
| 127 | } |
| 128 | |
| 129 | if (total_len < EI_NIDENT) { |
| 130 | fprintf(stderr, "%s: file too small (truncated?)\n", inf_name); |
| 131 | return EXIT_FAILURE; |
| 132 | } |
| 133 | |
| 134 | buf = malloc(total_len); |
| 135 | if (buf == NULL) { |
| 136 | goto perror_inf; |
| 137 | } |
| 138 | |
| 139 | errno = 0; |
| 140 | if (fread(buf, 1, total_len, inf) != total_len) { |
| 141 | if (errno) { |
| 142 | goto perror_inf; |
| 143 | } |
| 144 | fprintf(stderr, "%s: incomplete read\n", inf_name); |
| 145 | return EXIT_FAILURE; |
| 146 | } |
| 147 | |
| 148 | /* |
| 149 | * Identify which elf flavor we're processing. |
| 150 | * The first 16 bytes of the file are e_ident. |
| 151 | */ |
| 152 | |
| 153 | if (buf[EI_MAG0] != ELFMAG0 || buf[EI_MAG1] != ELFMAG1 || |
| 154 | buf[EI_MAG2] != ELFMAG2 || buf[EI_MAG3] != ELFMAG3) { |
| 155 | fprintf(stderr, "%s: not an elf file\n", inf_name); |
| 156 | return EXIT_FAILURE; |
| 157 | } |
| 158 | switch (buf[EI_DATA]) { |
| 159 | case ELFDATA2LSB: |
| 160 | need_bswap = BYTE_ORDER != LITTLE_ENDIAN; |
| 161 | break; |
| 162 | case ELFDATA2MSB: |
| 163 | need_bswap = BYTE_ORDER != BIG_ENDIAN; |
| 164 | break; |
| 165 | default: |
| 166 | fprintf(stderr, "%s: invalid elf EI_DATA (%u)\n", |
| 167 | inf_name, buf[EI_DATA]); |
| 168 | return EXIT_FAILURE; |
| 169 | } |
| 170 | |
| 171 | /* |
| 172 | * We need to relocate the VDSO image. The one built into the kernel |
| 173 | * is built for a fixed address. The one we built for QEMU is not, |
| 174 | * since that requires close control of the guest address space. |
| 175 | * |
| 176 | * Output relocation addresses as we go. |
| 177 | */ |
| 178 | |
| 179 | fprintf(outf, |
| 180 | "/* Automatically generated by linux-user/gen-vdso.c. */\n" |
| 181 | "\n" |
| 182 | "static const unsigned %s_relocs[] = {\n", prefix); |
| 183 | |
| 184 | switch (buf[EI_CLASS]) { |
| 185 | case ELFCLASS32: |
| 186 | elf32_process(outf, buf, total_len, need_bswap); |
| 187 | break; |
| 188 | case ELFCLASS64: |
| 189 | elf64_process(outf, buf, total_len, need_bswap); |
| 190 | break; |
| 191 | default: |
| 192 | fprintf(stderr, "%s: invalid elf EI_CLASS (%u)\n", |
| 193 | inf_name, buf[EI_CLASS]); |
| 194 | return EXIT_FAILURE; |
| 195 | } |
| 196 | |
| 197 | fprintf(outf, "};\n\n"); /* end vdso_relocs. */ |
| 198 | |
| 199 | /* |
| 200 | * Write out the vdso image now, after we made local changes. |
| 201 | */ |
| 202 | fprintf(outf, |
| 203 | "static const uint8_t %s_image[] = {", |
| 204 | prefix); |
| 205 | for (long i = 0; i < total_len; ++i) { |
| 206 | if (i % 12 == 0) { |
| 207 | fputs("\n ", outf); |
| 208 | } |
| 209 | fprintf(outf, " 0x%02x,", buf[i]); |
| 210 | } |
| 211 | fprintf(outf, "\n};\n\n"); |
| 212 | |
| 213 | fprintf(outf, "static const VdsoImageInfo %s_image_info = {\n", prefix); |
| 214 | fprintf(outf, " .image = %s_image,\n", prefix); |
| 215 | fprintf(outf, " .relocs = %s_relocs,\n", prefix); |
| 216 | fprintf(outf, " .image_size = sizeof(%s_image),\n", prefix); |
| 217 | fprintf(outf, " .reloc_count = ARRAY_SIZE(%s_relocs),\n", prefix); |
| 218 | fprintf(outf, " .sigreturn_ofs = 0x%x,\n", sigreturn_addr); |
| 219 | fprintf(outf, " .rt_sigreturn_ofs = 0x%x,\n", rt_sigreturn_addr); |
| 220 | fprintf(outf, " .sigreturn_region_start_ofs = 0x%x,\n", |
| 221 | sigreturn_region_start_addr); |
| 222 | fprintf(outf, " .sigreturn_region_end_ofs = 0x%x,\n", |
| 223 | sigreturn_region_end_addr); |
| 224 | fprintf(outf, "};\n"); |
| 225 | |
| 226 | ret = EXIT_SUCCESS; |
| 227 | |
| 228 | cleanup: |
| 229 | free(buf); |
| 230 | |
| 231 | if (outf && fclose(outf) != 0) { |
| 232 | ret = EXIT_FAILURE; |
| 233 | } |
| 234 | if (inf && fclose(inf) != 0) { |
| 235 | ret = EXIT_FAILURE; |
| 236 | } |
| 237 | return ret; |
| 238 | |
| 239 | perror_inf: |
| 240 | perror(inf_name); |
| 241 | goto cleanup; |
| 242 | |
| 243 | perror_outf: |
| 244 | perror(outf_name); |
| 245 | goto cleanup; |
| 246 | } |