1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * misc.c 4 * 5 * This is a collection of several routines used to extract the kernel 6 * which includes KASLR relocation, decompression, ELF parsing, and 7 * relocation processing. Additionally included are the screen and serial 8 * output functions and related debugging support functions. 9 * 10 * malloc by Hannu Savolainen 1993 and Matthias Urlichs 1994 11 * puts by Nick Holloway 1993, better puts by Martin Mares 1995 12 * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996 13 */ 14 15 #include "misc.h" 16 #include "error.h" 17 #include "pgtable.h" 18 #include "../string.h" 19 #include "../voffset.h" 20 21 /* 22 * WARNING!! 23 * This code is compiled with -fPIC and it is relocated dynamically at 24 * run time, but no relocation processing is performed. This means that 25 * it is not safe to place pointers in static structures. 26 */ 27 28 /* Macros used by the included decompressor code below. */ 29 #define STATIC static 30 31 /* 32 * Use normal definitions of mem*() from string.c. There are already 33 * included header files which expect a definition of memset() and by 34 * the time we define memset macro, it is too late. 35 */ 36 #undef memcpy 37 #undef memset 38 #define memzero(s, n) memset((s), 0, (n)) 39 #define memmove memmove 40 41 /* Functions used by the included decompressor code below. */ 42 void *memmove(void *dest, const void *src, size_t n); 43 44 /* 45 * This is set up by the setup-routine at boot-time 46 */ 47 struct boot_params *boot_params; 48 49 memptr free_mem_ptr; 50 memptr free_mem_end_ptr; 51 52 static char *vidmem; 53 static int vidport; 54 static int lines, cols; 55 56 #ifdef CONFIG_KERNEL_GZIP 57 #include "../../../../lib/decompress_inflate.c" 58 #endif 59 60 #ifdef CONFIG_KERNEL_BZIP2 61 #include "../../../../lib/decompress_bunzip2.c" 62 #endif 63 64 #ifdef CONFIG_KERNEL_LZMA 65 #include "../../../../lib/decompress_unlzma.c" 66 #endif 67 68 #ifdef CONFIG_KERNEL_XZ 69 #include "../../../../lib/decompress_unxz.c" 70 #endif 71 72 #ifdef CONFIG_KERNEL_LZO 73 #include "../../../../lib/decompress_unlzo.c" 74 #endif 75 76 #ifdef CONFIG_KERNEL_LZ4 77 #include "../../../../lib/decompress_unlz4.c" 78 #endif 79 /* 80 * NOTE: When adding a new decompressor, please update the analysis in 81 * ../header.S. 82 */ 83 84 static void scroll(void) 85 { 86 int i; 87 88 memmove(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2); 89 for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2) 90 vidmem[i] = ' '; 91 } 92 93 #define XMTRDY 0x20 94 95 #define TXR 0 /* Transmit register (WRITE) */ 96 #define LSR 5 /* Line Status */ 97 static void serial_putchar(int ch) 98 { 99 unsigned timeout = 0xffff; 100 101 while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout) 102 cpu_relax(); 103 104 outb(ch, early_serial_base + TXR); 105 } 106 107 void __putstr(const char *s) 108 { 109 int x, y, pos; 110 char c; 111 112 if (early_serial_base) { 113 const char *str = s; 114 while (*str) { 115 if (*str == '\n') 116 serial_putchar('\r'); 117 serial_putchar(*str++); 118 } 119 } 120 121 if (lines == 0 || cols == 0) 122 return; 123 124 x = boot_params->screen_info.orig_x; 125 y = boot_params->screen_info.orig_y; 126 127 while ((c = *s++) != '\0') { 128 if (c == '\n') { 129 x = 0; 130 if (++y >= lines) { 131 scroll(); 132 y--; 133 } 134 } else { 135 vidmem[(x + cols * y) * 2] = c; 136 if (++x >= cols) { 137 x = 0; 138 if (++y >= lines) { 139 scroll(); 140 y--; 141 } 142 } 143 } 144 } 145 146 boot_params->screen_info.orig_x = x; 147 boot_params->screen_info.orig_y = y; 148 149 pos = (x + cols * y) * 2; /* Update cursor position */ 150 outb(14, vidport); 151 outb(0xff & (pos >> 9), vidport+1); 152 outb(15, vidport); 153 outb(0xff & (pos >> 1), vidport+1); 154 } 155 156 void __puthex(unsigned long value) 157 { 158 char alpha[2] = "0"; 159 int bits; 160 161 for (bits = sizeof(value) * 8 - 4; bits >= 0; bits -= 4) { 162 unsigned long digit = (value >> bits) & 0xf; 163 164 if (digit < 0xA) 165 alpha[0] = '0' + digit; 166 else 167 alpha[0] = 'a' + (digit - 0xA); 168 169 __putstr(alpha); 170 } 171 } 172 173 #if CONFIG_X86_NEED_RELOCS 174 static void handle_relocations(void *output, unsigned long output_len, 175 unsigned long virt_addr) 176 { 177 int *reloc; 178 unsigned long delta, map, ptr; 179 unsigned long min_addr = (unsigned long)output; 180 unsigned long max_addr = min_addr + (VO___bss_start - VO__text); 181 182 /* 183 * Calculate the delta between where vmlinux was linked to load 184 * and where it was actually loaded. 185 */ 186 delta = min_addr - LOAD_PHYSICAL_ADDR; 187 188 /* 189 * The kernel contains a table of relocation addresses. Those 190 * addresses have the final load address of the kernel in virtual 191 * memory. We are currently working in the self map. So we need to 192 * create an adjustment for kernel memory addresses to the self map. 193 * This will involve subtracting out the base address of the kernel. 194 */ 195 map = delta - __START_KERNEL_map; 196 197 /* 198 * 32-bit always performs relocations. 64-bit relocations are only 199 * needed if KASLR has chosen a different starting address offset 200 * from __START_KERNEL_map. 201 */ 202 if (IS_ENABLED(CONFIG_X86_64)) 203 delta = virt_addr - LOAD_PHYSICAL_ADDR; 204 205 if (!delta) { 206 debug_putstr("No relocation needed... "); 207 return; 208 } 209 debug_putstr("Performing relocations... "); 210 211 /* 212 * Process relocations: 32 bit relocations first then 64 bit after. 213 * Three sets of binary relocations are added to the end of the kernel 214 * before compression. Each relocation table entry is the kernel 215 * address of the location which needs to be updated stored as a 216 * 32-bit value which is sign extended to 64 bits. 217 * 218 * Format is: 219 * 220 * kernel bits... 221 * 0 - zero terminator for 64 bit relocations 222 * 64 bit relocation repeated 223 * 0 - zero terminator for inverse 32 bit relocations 224 * 32 bit inverse relocation repeated 225 * 0 - zero terminator for 32 bit relocations 226 * 32 bit relocation repeated 227 * 228 * So we work backwards from the end of the decompressed image. 229 */ 230 for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) { 231 long extended = *reloc; 232 extended += map; 233 234 ptr = (unsigned long)extended; 235 if (ptr < min_addr || ptr > max_addr) 236 error("32-bit relocation outside of kernel!\n"); 237 238 *(uint32_t *)ptr += delta; 239 } 240 #ifdef CONFIG_X86_64 241 while (*--reloc) { 242 long extended = *reloc; 243 extended += map; 244 245 ptr = (unsigned long)extended; 246 if (ptr < min_addr || ptr > max_addr) 247 error("inverse 32-bit relocation outside of kernel!\n"); 248 249 *(int32_t *)ptr -= delta; 250 } 251 for (reloc--; *reloc; reloc--) { 252 long extended = *reloc; 253 extended += map; 254 255 ptr = (unsigned long)extended; 256 if (ptr < min_addr || ptr > max_addr) 257 error("64-bit relocation outside of kernel!\n"); 258 259 *(uint64_t *)ptr += delta; 260 } 261 #endif 262 } 263 #else 264 static inline void handle_relocations(void *output, unsigned long output_len, 265 unsigned long virt_addr) 266 { } 267 #endif 268 269 static void parse_elf(void *output) 270 { 271 #ifdef CONFIG_X86_64 272 Elf64_Ehdr ehdr; 273 Elf64_Phdr *phdrs, *phdr; 274 #else 275 Elf32_Ehdr ehdr; 276 Elf32_Phdr *phdrs, *phdr; 277 #endif 278 void *dest; 279 int i; 280 281 memcpy(&ehdr, output, sizeof(ehdr)); 282 if (ehdr.e_ident[EI_MAG0] != ELFMAG0 || 283 ehdr.e_ident[EI_MAG1] != ELFMAG1 || 284 ehdr.e_ident[EI_MAG2] != ELFMAG2 || 285 ehdr.e_ident[EI_MAG3] != ELFMAG3) { 286 error("Kernel is not a valid ELF file"); 287 return; 288 } 289 290 debug_putstr("Parsing ELF... "); 291 292 phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum); 293 if (!phdrs) 294 error("Failed to allocate space for phdrs"); 295 296 memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum); 297 298 for (i = 0; i < ehdr.e_phnum; i++) { 299 phdr = &phdrs[i]; 300 301 switch (phdr->p_type) { 302 case PT_LOAD: 303 #ifdef CONFIG_X86_64 304 if ((phdr->p_align % 0x200000) != 0) 305 error("Alignment of LOAD segment isn't multiple of 2MB"); 306 #endif 307 #ifdef CONFIG_RELOCATABLE 308 dest = output; 309 dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR); 310 #else 311 dest = (void *)(phdr->p_paddr); 312 #endif 313 memmove(dest, output + phdr->p_offset, phdr->p_filesz); 314 break; 315 default: /* Ignore other PT_* */ break; 316 } 317 } 318 319 free(phdrs); 320 } 321 322 /* 323 * The compressed kernel image (ZO), has been moved so that its position 324 * is against the end of the buffer used to hold the uncompressed kernel 325 * image (VO) and the execution environment (.bss, .brk), which makes sure 326 * there is room to do the in-place decompression. (See header.S for the 327 * calculations.) 328 * 329 * |-----compressed kernel image------| 330 * V V 331 * 0 extract_offset +INIT_SIZE 332 * |-----------|---------------|-------------------------|--------| 333 * | | | | 334 * VO__text startup_32 of ZO VO__end ZO__end 335 * ^ ^ 336 * |-------uncompressed kernel image---------| 337 * 338 */ 339 asmlinkage __visible void *extract_kernel(void *rmode, memptr heap, 340 unsigned char *input_data, 341 unsigned long input_len, 342 unsigned char *output, 343 unsigned long output_len) 344 { 345 const unsigned long kernel_total_size = VO__end - VO__text; 346 unsigned long virt_addr = LOAD_PHYSICAL_ADDR; 347 348 /* Retain x86 boot parameters pointer passed from startup_32/64. */ 349 boot_params = rmode; 350 351 /* Clear flags intended for solely in-kernel use. */ 352 boot_params->hdr.loadflags &= ~KASLR_FLAG; 353 354 /* Save RSDP address for later use. */ 355 boot_params->acpi_rsdp_addr = get_rsdp_addr(); 356 357 sanitize_boot_params(boot_params); 358 359 if (boot_params->screen_info.orig_video_mode == 7) { 360 vidmem = (char *) 0xb0000; 361 vidport = 0x3b4; 362 } else { 363 vidmem = (char *) 0xb8000; 364 vidport = 0x3d4; 365 } 366 367 lines = boot_params->screen_info.orig_video_lines; 368 cols = boot_params->screen_info.orig_video_cols; 369 370 console_init(); 371 debug_putstr("early console in extract_kernel\n"); 372 373 free_mem_ptr = heap; /* Heap */ 374 free_mem_end_ptr = heap + BOOT_HEAP_SIZE; 375 376 /* Report initial kernel position details. */ 377 debug_putaddr(input_data); 378 debug_putaddr(input_len); 379 debug_putaddr(output); 380 debug_putaddr(output_len); 381 debug_putaddr(kernel_total_size); 382 383 #ifdef CONFIG_X86_64 384 /* Report address of 32-bit trampoline */ 385 debug_putaddr(trampoline_32bit); 386 #endif 387 388 /* 389 * The memory hole needed for the kernel is the larger of either 390 * the entire decompressed kernel plus relocation table, or the 391 * entire decompressed kernel plus .bss and .brk sections. 392 */ 393 choose_random_location((unsigned long)input_data, input_len, 394 (unsigned long *)&output, 395 max(output_len, kernel_total_size), 396 &virt_addr); 397 398 /* Validate memory location choices. */ 399 if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1)) 400 error("Destination physical address inappropriately aligned"); 401 if (virt_addr & (MIN_KERNEL_ALIGN - 1)) 402 error("Destination virtual address inappropriately aligned"); 403 #ifdef CONFIG_X86_64 404 if (heap > 0x3fffffffffffUL) 405 error("Destination address too large"); 406 if (virt_addr + max(output_len, kernel_total_size) > KERNEL_IMAGE_SIZE) 407 error("Destination virtual address is beyond the kernel mapping area"); 408 #else 409 if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff)) 410 error("Destination address too large"); 411 #endif 412 #ifndef CONFIG_RELOCATABLE 413 if ((unsigned long)output != LOAD_PHYSICAL_ADDR) 414 error("Destination address does not match LOAD_PHYSICAL_ADDR"); 415 if (virt_addr != LOAD_PHYSICAL_ADDR) 416 error("Destination virtual address changed when not relocatable"); 417 #endif 418 419 debug_putstr("\nDecompressing Linux... "); 420 __decompress(input_data, input_len, NULL, NULL, output, output_len, 421 NULL, error); 422 parse_elf(output); 423 handle_relocations(output, output_len, virt_addr); 424 debug_putstr("done.\nBooting the kernel.\n"); 425 return output; 426 } 427 428 void fortify_panic(const char *name) 429 { 430 error("detected buffer overflow"); 431 } 432