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 57 /* These might be accessed before .bss is cleared, so use .data instead. */ 58 static int lines __section(".data"); 59 static int cols __section(".data"); 60 61 #ifdef CONFIG_KERNEL_GZIP 62 #include "../../../../lib/decompress_inflate.c" 63 #endif 64 65 #ifdef CONFIG_KERNEL_BZIP2 66 #include "../../../../lib/decompress_bunzip2.c" 67 #endif 68 69 #ifdef CONFIG_KERNEL_LZMA 70 #include "../../../../lib/decompress_unlzma.c" 71 #endif 72 73 #ifdef CONFIG_KERNEL_XZ 74 #include "../../../../lib/decompress_unxz.c" 75 #endif 76 77 #ifdef CONFIG_KERNEL_LZO 78 #include "../../../../lib/decompress_unlzo.c" 79 #endif 80 81 #ifdef CONFIG_KERNEL_LZ4 82 #include "../../../../lib/decompress_unlz4.c" 83 #endif 84 85 #ifdef CONFIG_KERNEL_ZSTD 86 #include "../../../../lib/decompress_unzstd.c" 87 #endif 88 /* 89 * NOTE: When adding a new decompressor, please update the analysis in 90 * ../header.S. 91 */ 92 93 static void scroll(void) 94 { 95 int i; 96 97 memmove(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2); 98 for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2) 99 vidmem[i] = ' '; 100 } 101 102 #define XMTRDY 0x20 103 104 #define TXR 0 /* Transmit register (WRITE) */ 105 #define LSR 5 /* Line Status */ 106 static void serial_putchar(int ch) 107 { 108 unsigned timeout = 0xffff; 109 110 while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout) 111 cpu_relax(); 112 113 outb(ch, early_serial_base + TXR); 114 } 115 116 void __putstr(const char *s) 117 { 118 int x, y, pos; 119 char c; 120 121 if (early_serial_base) { 122 const char *str = s; 123 while (*str) { 124 if (*str == '\n') 125 serial_putchar('\r'); 126 serial_putchar(*str++); 127 } 128 } 129 130 if (lines == 0 || cols == 0) 131 return; 132 133 x = boot_params->screen_info.orig_x; 134 y = boot_params->screen_info.orig_y; 135 136 while ((c = *s++) != '\0') { 137 if (c == '\n') { 138 x = 0; 139 if (++y >= lines) { 140 scroll(); 141 y--; 142 } 143 } else { 144 vidmem[(x + cols * y) * 2] = c; 145 if (++x >= cols) { 146 x = 0; 147 if (++y >= lines) { 148 scroll(); 149 y--; 150 } 151 } 152 } 153 } 154 155 boot_params->screen_info.orig_x = x; 156 boot_params->screen_info.orig_y = y; 157 158 pos = (x + cols * y) * 2; /* Update cursor position */ 159 outb(14, vidport); 160 outb(0xff & (pos >> 9), vidport+1); 161 outb(15, vidport); 162 outb(0xff & (pos >> 1), vidport+1); 163 } 164 165 void __puthex(unsigned long value) 166 { 167 char alpha[2] = "0"; 168 int bits; 169 170 for (bits = sizeof(value) * 8 - 4; bits >= 0; bits -= 4) { 171 unsigned long digit = (value >> bits) & 0xf; 172 173 if (digit < 0xA) 174 alpha[0] = '0' + digit; 175 else 176 alpha[0] = 'a' + (digit - 0xA); 177 178 __putstr(alpha); 179 } 180 } 181 182 #ifdef CONFIG_X86_NEED_RELOCS 183 static void handle_relocations(void *output, unsigned long output_len, 184 unsigned long virt_addr) 185 { 186 int *reloc; 187 unsigned long delta, map, ptr; 188 unsigned long min_addr = (unsigned long)output; 189 unsigned long max_addr = min_addr + (VO___bss_start - VO__text); 190 191 /* 192 * Calculate the delta between where vmlinux was linked to load 193 * and where it was actually loaded. 194 */ 195 delta = min_addr - LOAD_PHYSICAL_ADDR; 196 197 /* 198 * The kernel contains a table of relocation addresses. Those 199 * addresses have the final load address of the kernel in virtual 200 * memory. We are currently working in the self map. So we need to 201 * create an adjustment for kernel memory addresses to the self map. 202 * This will involve subtracting out the base address of the kernel. 203 */ 204 map = delta - __START_KERNEL_map; 205 206 /* 207 * 32-bit always performs relocations. 64-bit relocations are only 208 * needed if KASLR has chosen a different starting address offset 209 * from __START_KERNEL_map. 210 */ 211 if (IS_ENABLED(CONFIG_X86_64)) 212 delta = virt_addr - LOAD_PHYSICAL_ADDR; 213 214 if (!delta) { 215 debug_putstr("No relocation needed... "); 216 return; 217 } 218 debug_putstr("Performing relocations... "); 219 220 /* 221 * Process relocations: 32 bit relocations first then 64 bit after. 222 * Three sets of binary relocations are added to the end of the kernel 223 * before compression. Each relocation table entry is the kernel 224 * address of the location which needs to be updated stored as a 225 * 32-bit value which is sign extended to 64 bits. 226 * 227 * Format is: 228 * 229 * kernel bits... 230 * 0 - zero terminator for 64 bit relocations 231 * 64 bit relocation repeated 232 * 0 - zero terminator for inverse 32 bit relocations 233 * 32 bit inverse relocation repeated 234 * 0 - zero terminator for 32 bit relocations 235 * 32 bit relocation repeated 236 * 237 * So we work backwards from the end of the decompressed image. 238 */ 239 for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) { 240 long extended = *reloc; 241 extended += map; 242 243 ptr = (unsigned long)extended; 244 if (ptr < min_addr || ptr > max_addr) 245 error("32-bit relocation outside of kernel!\n"); 246 247 *(uint32_t *)ptr += delta; 248 } 249 #ifdef CONFIG_X86_64 250 while (*--reloc) { 251 long extended = *reloc; 252 extended += map; 253 254 ptr = (unsigned long)extended; 255 if (ptr < min_addr || ptr > max_addr) 256 error("inverse 32-bit relocation outside of kernel!\n"); 257 258 *(int32_t *)ptr -= delta; 259 } 260 for (reloc--; *reloc; reloc--) { 261 long extended = *reloc; 262 extended += map; 263 264 ptr = (unsigned long)extended; 265 if (ptr < min_addr || ptr > max_addr) 266 error("64-bit relocation outside of kernel!\n"); 267 268 *(uint64_t *)ptr += delta; 269 } 270 #endif 271 } 272 #else 273 static inline void handle_relocations(void *output, unsigned long output_len, 274 unsigned long virt_addr) 275 { } 276 #endif 277 278 static void parse_elf(void *output) 279 { 280 #ifdef CONFIG_X86_64 281 Elf64_Ehdr ehdr; 282 Elf64_Phdr *phdrs, *phdr; 283 #else 284 Elf32_Ehdr ehdr; 285 Elf32_Phdr *phdrs, *phdr; 286 #endif 287 void *dest; 288 int i; 289 290 memcpy(&ehdr, output, sizeof(ehdr)); 291 if (ehdr.e_ident[EI_MAG0] != ELFMAG0 || 292 ehdr.e_ident[EI_MAG1] != ELFMAG1 || 293 ehdr.e_ident[EI_MAG2] != ELFMAG2 || 294 ehdr.e_ident[EI_MAG3] != ELFMAG3) { 295 error("Kernel is not a valid ELF file"); 296 return; 297 } 298 299 debug_putstr("Parsing ELF... "); 300 301 phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum); 302 if (!phdrs) 303 error("Failed to allocate space for phdrs"); 304 305 memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum); 306 307 for (i = 0; i < ehdr.e_phnum; i++) { 308 phdr = &phdrs[i]; 309 310 switch (phdr->p_type) { 311 case PT_LOAD: 312 #ifdef CONFIG_X86_64 313 if ((phdr->p_align % 0x200000) != 0) 314 error("Alignment of LOAD segment isn't multiple of 2MB"); 315 #endif 316 #ifdef CONFIG_RELOCATABLE 317 dest = output; 318 dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR); 319 #else 320 dest = (void *)(phdr->p_paddr); 321 #endif 322 memmove(dest, output + phdr->p_offset, phdr->p_filesz); 323 break; 324 default: /* Ignore other PT_* */ break; 325 } 326 } 327 328 free(phdrs); 329 } 330 331 /* 332 * The compressed kernel image (ZO), has been moved so that its position 333 * is against the end of the buffer used to hold the uncompressed kernel 334 * image (VO) and the execution environment (.bss, .brk), which makes sure 335 * there is room to do the in-place decompression. (See header.S for the 336 * calculations.) 337 * 338 * |-----compressed kernel image------| 339 * V V 340 * 0 extract_offset +INIT_SIZE 341 * |-----------|---------------|-------------------------|--------| 342 * | | | | 343 * VO__text startup_32 of ZO VO__end ZO__end 344 * ^ ^ 345 * |-------uncompressed kernel image---------| 346 * 347 */ 348 asmlinkage __visible void *extract_kernel(void *rmode, memptr heap, 349 unsigned char *input_data, 350 unsigned long input_len, 351 unsigned char *output, 352 unsigned long output_len) 353 { 354 const unsigned long kernel_total_size = VO__end - VO__text; 355 unsigned long virt_addr = LOAD_PHYSICAL_ADDR; 356 unsigned long needed_size; 357 358 /* Retain x86 boot parameters pointer passed from startup_32/64. */ 359 boot_params = rmode; 360 361 /* Clear flags intended for solely in-kernel use. */ 362 boot_params->hdr.loadflags &= ~KASLR_FLAG; 363 364 sanitize_boot_params(boot_params); 365 366 if (boot_params->screen_info.orig_video_mode == 7) { 367 vidmem = (char *) 0xb0000; 368 vidport = 0x3b4; 369 } else { 370 vidmem = (char *) 0xb8000; 371 vidport = 0x3d4; 372 } 373 374 lines = boot_params->screen_info.orig_video_lines; 375 cols = boot_params->screen_info.orig_video_cols; 376 377 console_init(); 378 379 /* 380 * Save RSDP address for later use. Have this after console_init() 381 * so that early debugging output from the RSDP parsing code can be 382 * collected. 383 */ 384 boot_params->acpi_rsdp_addr = get_rsdp_addr(); 385 386 debug_putstr("early console in extract_kernel\n"); 387 388 free_mem_ptr = heap; /* Heap */ 389 free_mem_end_ptr = heap + BOOT_HEAP_SIZE; 390 391 /* 392 * The memory hole needed for the kernel is the larger of either 393 * the entire decompressed kernel plus relocation table, or the 394 * entire decompressed kernel plus .bss and .brk sections. 395 * 396 * On X86_64, the memory is mapped with PMD pages. Round the 397 * size up so that the full extent of PMD pages mapped is 398 * included in the check against the valid memory table 399 * entries. This ensures the full mapped area is usable RAM 400 * and doesn't include any reserved areas. 401 */ 402 needed_size = max(output_len, kernel_total_size); 403 #ifdef CONFIG_X86_64 404 needed_size = ALIGN(needed_size, MIN_KERNEL_ALIGN); 405 #endif 406 407 /* Report initial kernel position details. */ 408 debug_putaddr(input_data); 409 debug_putaddr(input_len); 410 debug_putaddr(output); 411 debug_putaddr(output_len); 412 debug_putaddr(kernel_total_size); 413 debug_putaddr(needed_size); 414 415 #ifdef CONFIG_X86_64 416 /* Report address of 32-bit trampoline */ 417 debug_putaddr(trampoline_32bit); 418 #endif 419 420 choose_random_location((unsigned long)input_data, input_len, 421 (unsigned long *)&output, 422 needed_size, 423 &virt_addr); 424 425 /* Validate memory location choices. */ 426 if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1)) 427 error("Destination physical address inappropriately aligned"); 428 if (virt_addr & (MIN_KERNEL_ALIGN - 1)) 429 error("Destination virtual address inappropriately aligned"); 430 #ifdef CONFIG_X86_64 431 if (heap > 0x3fffffffffffUL) 432 error("Destination address too large"); 433 if (virt_addr + max(output_len, kernel_total_size) > KERNEL_IMAGE_SIZE) 434 error("Destination virtual address is beyond the kernel mapping area"); 435 #else 436 if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff)) 437 error("Destination address too large"); 438 #endif 439 #ifndef CONFIG_RELOCATABLE 440 if (virt_addr != LOAD_PHYSICAL_ADDR) 441 error("Destination virtual address changed when not relocatable"); 442 #endif 443 444 debug_putstr("\nDecompressing Linux... "); 445 __decompress(input_data, input_len, NULL, NULL, output, output_len, 446 NULL, error); 447 parse_elf(output); 448 handle_relocations(output, output_len, virt_addr); 449 debug_putstr("done.\nBooting the kernel.\n"); 450 451 /* Disable exception handling before booting the kernel */ 452 cleanup_exception_handling(); 453 454 return output; 455 } 456 457 void fortify_panic(const char *name) 458 { 459 error("detected buffer overflow"); 460 } 461