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 #include <asm/bootparam_utils.h> 21 22 /* 23 * WARNING!! 24 * This code is compiled with -fPIC and it is relocated dynamically at 25 * run time, but no relocation processing is performed. This means that 26 * it is not safe to place pointers in static structures. 27 */ 28 29 /* Macros used by the included decompressor code below. */ 30 #define STATIC static 31 /* Define an externally visible malloc()/free(). */ 32 #define MALLOC_VISIBLE 33 #include <linux/decompress/mm.h> 34 35 /* 36 * Provide definitions of memzero and memmove as some of the decompressors will 37 * try to define their own functions if these are not defined as macros. 38 */ 39 #define memzero(s, n) memset((s), 0, (n)) 40 #ifndef memmove 41 #define memmove memmove 42 /* Functions used by the included decompressor code below. */ 43 void *memmove(void *dest, const void *src, size_t n); 44 #endif 45 46 /* 47 * This is set up by the setup-routine at boot-time 48 */ 49 struct boot_params *boot_params; 50 51 memptr free_mem_ptr; 52 memptr free_mem_end_ptr; 53 54 static char *vidmem; 55 static int vidport; 56 static int lines, cols; 57 58 #ifdef CONFIG_KERNEL_GZIP 59 #include "../../../../lib/decompress_inflate.c" 60 #endif 61 62 #ifdef CONFIG_KERNEL_BZIP2 63 #include "../../../../lib/decompress_bunzip2.c" 64 #endif 65 66 #ifdef CONFIG_KERNEL_LZMA 67 #include "../../../../lib/decompress_unlzma.c" 68 #endif 69 70 #ifdef CONFIG_KERNEL_XZ 71 #include "../../../../lib/decompress_unxz.c" 72 #endif 73 74 #ifdef CONFIG_KERNEL_LZO 75 #include "../../../../lib/decompress_unlzo.c" 76 #endif 77 78 #ifdef CONFIG_KERNEL_LZ4 79 #include "../../../../lib/decompress_unlz4.c" 80 #endif 81 82 #ifdef CONFIG_KERNEL_ZSTD 83 #include "../../../../lib/decompress_unzstd.c" 84 #endif 85 /* 86 * NOTE: When adding a new decompressor, please update the analysis in 87 * ../header.S. 88 */ 89 90 static void scroll(void) 91 { 92 int i; 93 94 memmove(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2); 95 for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2) 96 vidmem[i] = ' '; 97 } 98 99 #define XMTRDY 0x20 100 101 #define TXR 0 /* Transmit register (WRITE) */ 102 #define LSR 5 /* Line Status */ 103 static void serial_putchar(int ch) 104 { 105 unsigned timeout = 0xffff; 106 107 while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout) 108 cpu_relax(); 109 110 outb(ch, early_serial_base + TXR); 111 } 112 113 void __putstr(const char *s) 114 { 115 int x, y, pos; 116 char c; 117 118 if (early_serial_base) { 119 const char *str = s; 120 while (*str) { 121 if (*str == '\n') 122 serial_putchar('\r'); 123 serial_putchar(*str++); 124 } 125 } 126 127 if (lines == 0 || cols == 0) 128 return; 129 130 x = boot_params->screen_info.orig_x; 131 y = boot_params->screen_info.orig_y; 132 133 while ((c = *s++) != '\0') { 134 if (c == '\n') { 135 x = 0; 136 if (++y >= lines) { 137 scroll(); 138 y--; 139 } 140 } else { 141 vidmem[(x + cols * y) * 2] = c; 142 if (++x >= cols) { 143 x = 0; 144 if (++y >= lines) { 145 scroll(); 146 y--; 147 } 148 } 149 } 150 } 151 152 boot_params->screen_info.orig_x = x; 153 boot_params->screen_info.orig_y = y; 154 155 pos = (x + cols * y) * 2; /* Update cursor position */ 156 outb(14, vidport); 157 outb(0xff & (pos >> 9), vidport+1); 158 outb(15, vidport); 159 outb(0xff & (pos >> 1), vidport+1); 160 } 161 162 void __puthex(unsigned long value) 163 { 164 char alpha[2] = "0"; 165 int bits; 166 167 for (bits = sizeof(value) * 8 - 4; bits >= 0; bits -= 4) { 168 unsigned long digit = (value >> bits) & 0xf; 169 170 if (digit < 0xA) 171 alpha[0] = '0' + digit; 172 else 173 alpha[0] = 'a' + (digit - 0xA); 174 175 __putstr(alpha); 176 } 177 } 178 179 #ifdef CONFIG_X86_NEED_RELOCS 180 static void handle_relocations(void *output, unsigned long output_len, 181 unsigned long virt_addr) 182 { 183 int *reloc; 184 unsigned long delta, map, ptr; 185 unsigned long min_addr = (unsigned long)output; 186 unsigned long max_addr = min_addr + (VO___bss_start - VO__text); 187 188 /* 189 * Calculate the delta between where vmlinux was linked to load 190 * and where it was actually loaded. 191 */ 192 delta = min_addr - LOAD_PHYSICAL_ADDR; 193 194 /* 195 * The kernel contains a table of relocation addresses. Those 196 * addresses have the final load address of the kernel in virtual 197 * memory. We are currently working in the self map. So we need to 198 * create an adjustment for kernel memory addresses to the self map. 199 * This will involve subtracting out the base address of the kernel. 200 */ 201 map = delta - __START_KERNEL_map; 202 203 /* 204 * 32-bit always performs relocations. 64-bit relocations are only 205 * needed if KASLR has chosen a different starting address offset 206 * from __START_KERNEL_map. 207 */ 208 if (IS_ENABLED(CONFIG_X86_64)) 209 delta = virt_addr - LOAD_PHYSICAL_ADDR; 210 211 if (!delta) { 212 debug_putstr("No relocation needed... "); 213 return; 214 } 215 debug_putstr("Performing relocations... "); 216 217 /* 218 * Process relocations: 32 bit relocations first then 64 bit after. 219 * Three sets of binary relocations are added to the end of the kernel 220 * before compression. Each relocation table entry is the kernel 221 * address of the location which needs to be updated stored as a 222 * 32-bit value which is sign extended to 64 bits. 223 * 224 * Format is: 225 * 226 * kernel bits... 227 * 0 - zero terminator for 64 bit relocations 228 * 64 bit relocation repeated 229 * 0 - zero terminator for inverse 32 bit relocations 230 * 32 bit inverse relocation repeated 231 * 0 - zero terminator for 32 bit relocations 232 * 32 bit relocation repeated 233 * 234 * So we work backwards from the end of the decompressed image. 235 */ 236 for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) { 237 long extended = *reloc; 238 extended += map; 239 240 ptr = (unsigned long)extended; 241 if (ptr < min_addr || ptr > max_addr) 242 error("32-bit relocation outside of kernel!\n"); 243 244 *(uint32_t *)ptr += delta; 245 } 246 #ifdef CONFIG_X86_64 247 while (*--reloc) { 248 long extended = *reloc; 249 extended += map; 250 251 ptr = (unsigned long)extended; 252 if (ptr < min_addr || ptr > max_addr) 253 error("inverse 32-bit relocation outside of kernel!\n"); 254 255 *(int32_t *)ptr -= delta; 256 } 257 for (reloc--; *reloc; reloc--) { 258 long extended = *reloc; 259 extended += map; 260 261 ptr = (unsigned long)extended; 262 if (ptr < min_addr || ptr > max_addr) 263 error("64-bit relocation outside of kernel!\n"); 264 265 *(uint64_t *)ptr += delta; 266 } 267 #endif 268 } 269 #else 270 static inline void handle_relocations(void *output, unsigned long output_len, 271 unsigned long virt_addr) 272 { } 273 #endif 274 275 static void parse_elf(void *output) 276 { 277 #ifdef CONFIG_X86_64 278 Elf64_Ehdr ehdr; 279 Elf64_Phdr *phdrs, *phdr; 280 #else 281 Elf32_Ehdr ehdr; 282 Elf32_Phdr *phdrs, *phdr; 283 #endif 284 void *dest; 285 int i; 286 287 memcpy(&ehdr, output, sizeof(ehdr)); 288 if (ehdr.e_ident[EI_MAG0] != ELFMAG0 || 289 ehdr.e_ident[EI_MAG1] != ELFMAG1 || 290 ehdr.e_ident[EI_MAG2] != ELFMAG2 || 291 ehdr.e_ident[EI_MAG3] != ELFMAG3) { 292 error("Kernel is not a valid ELF file"); 293 return; 294 } 295 296 debug_putstr("Parsing ELF... "); 297 298 phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum); 299 if (!phdrs) 300 error("Failed to allocate space for phdrs"); 301 302 memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum); 303 304 for (i = 0; i < ehdr.e_phnum; i++) { 305 phdr = &phdrs[i]; 306 307 switch (phdr->p_type) { 308 case PT_LOAD: 309 #ifdef CONFIG_X86_64 310 if ((phdr->p_align % 0x200000) != 0) 311 error("Alignment of LOAD segment isn't multiple of 2MB"); 312 #endif 313 #ifdef CONFIG_RELOCATABLE 314 dest = output; 315 dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR); 316 #else 317 dest = (void *)(phdr->p_paddr); 318 #endif 319 memmove(dest, output + phdr->p_offset, phdr->p_filesz); 320 break; 321 default: /* Ignore other PT_* */ break; 322 } 323 } 324 325 free(phdrs); 326 } 327 328 /* 329 * The compressed kernel image (ZO), has been moved so that its position 330 * is against the end of the buffer used to hold the uncompressed kernel 331 * image (VO) and the execution environment (.bss, .brk), which makes sure 332 * there is room to do the in-place decompression. (See header.S for the 333 * calculations.) 334 * 335 * |-----compressed kernel image------| 336 * V V 337 * 0 extract_offset +INIT_SIZE 338 * |-----------|---------------|-------------------------|--------| 339 * | | | | 340 * VO__text startup_32 of ZO VO__end ZO__end 341 * ^ ^ 342 * |-------uncompressed kernel image---------| 343 * 344 */ 345 asmlinkage __visible void *extract_kernel(void *rmode, memptr heap, 346 unsigned char *input_data, 347 unsigned long input_len, 348 unsigned char *output, 349 unsigned long output_len) 350 { 351 const unsigned long kernel_total_size = VO__end - VO__text; 352 unsigned long virt_addr = LOAD_PHYSICAL_ADDR; 353 unsigned long needed_size; 354 355 /* Retain x86 boot parameters pointer passed from startup_32/64. */ 356 boot_params = rmode; 357 358 /* Clear flags intended for solely in-kernel use. */ 359 boot_params->hdr.loadflags &= ~KASLR_FLAG; 360 361 sanitize_boot_params(boot_params); 362 363 if (boot_params->screen_info.orig_video_mode == 7) { 364 vidmem = (char *) 0xb0000; 365 vidport = 0x3b4; 366 } else { 367 vidmem = (char *) 0xb8000; 368 vidport = 0x3d4; 369 } 370 371 lines = boot_params->screen_info.orig_video_lines; 372 cols = boot_params->screen_info.orig_video_cols; 373 374 console_init(); 375 376 /* 377 * Save RSDP address for later use. Have this after console_init() 378 * so that early debugging output from the RSDP parsing code can be 379 * collected. 380 */ 381 boot_params->acpi_rsdp_addr = get_rsdp_addr(); 382 383 debug_putstr("early console in extract_kernel\n"); 384 385 free_mem_ptr = heap; /* Heap */ 386 free_mem_end_ptr = heap + BOOT_HEAP_SIZE; 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 * On X86_64, the memory is mapped with PMD pages. Round the 394 * size up so that the full extent of PMD pages mapped is 395 * included in the check against the valid memory table 396 * entries. This ensures the full mapped area is usable RAM 397 * and doesn't include any reserved areas. 398 */ 399 needed_size = max(output_len, kernel_total_size); 400 #ifdef CONFIG_X86_64 401 needed_size = ALIGN(needed_size, MIN_KERNEL_ALIGN); 402 #endif 403 404 /* Report initial kernel position details. */ 405 debug_putaddr(input_data); 406 debug_putaddr(input_len); 407 debug_putaddr(output); 408 debug_putaddr(output_len); 409 debug_putaddr(kernel_total_size); 410 debug_putaddr(needed_size); 411 412 #ifdef CONFIG_X86_64 413 /* Report address of 32-bit trampoline */ 414 debug_putaddr(trampoline_32bit); 415 #endif 416 417 choose_random_location((unsigned long)input_data, input_len, 418 (unsigned long *)&output, 419 needed_size, 420 &virt_addr); 421 422 /* Validate memory location choices. */ 423 if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1)) 424 error("Destination physical address inappropriately aligned"); 425 if (virt_addr & (MIN_KERNEL_ALIGN - 1)) 426 error("Destination virtual address inappropriately aligned"); 427 #ifdef CONFIG_X86_64 428 if (heap > 0x3fffffffffffUL) 429 error("Destination address too large"); 430 if (virt_addr + max(output_len, kernel_total_size) > KERNEL_IMAGE_SIZE) 431 error("Destination virtual address is beyond the kernel mapping area"); 432 #else 433 if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff)) 434 error("Destination address too large"); 435 #endif 436 #ifndef CONFIG_RELOCATABLE 437 if (virt_addr != LOAD_PHYSICAL_ADDR) 438 error("Destination virtual address changed when not relocatable"); 439 #endif 440 441 debug_putstr("\nDecompressing Linux... "); 442 __decompress(input_data, input_len, NULL, NULL, output, output_len, 443 NULL, error); 444 parse_elf(output); 445 handle_relocations(output, output_len, virt_addr); 446 debug_putstr("done.\nBooting the kernel.\n"); 447 448 /* Disable exception handling before booting the kernel */ 449 cleanup_exception_handling(); 450 451 return output; 452 } 453 454 void fortify_panic(const char *name) 455 { 456 error("detected buffer overflow"); 457 } 458