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_ptr; 50 51 struct port_io_ops pio_ops; 52 53 memptr free_mem_ptr; 54 memptr free_mem_end_ptr; 55 int spurious_nmi_count; 56 57 static char *vidmem; 58 static int vidport; 59 60 /* These might be accessed before .bss is cleared, so use .data instead. */ 61 static int lines __section(".data"); 62 static int cols __section(".data"); 63 64 #ifdef CONFIG_KERNEL_GZIP 65 #include "../../../../lib/decompress_inflate.c" 66 #endif 67 68 #ifdef CONFIG_KERNEL_BZIP2 69 #include "../../../../lib/decompress_bunzip2.c" 70 #endif 71 72 #ifdef CONFIG_KERNEL_LZMA 73 #include "../../../../lib/decompress_unlzma.c" 74 #endif 75 76 #ifdef CONFIG_KERNEL_XZ 77 #include "../../../../lib/decompress_unxz.c" 78 #endif 79 80 #ifdef CONFIG_KERNEL_LZO 81 #include "../../../../lib/decompress_unlzo.c" 82 #endif 83 84 #ifdef CONFIG_KERNEL_LZ4 85 #include "../../../../lib/decompress_unlz4.c" 86 #endif 87 88 #ifdef CONFIG_KERNEL_ZSTD 89 #include "../../../../lib/decompress_unzstd.c" 90 #endif 91 /* 92 * NOTE: When adding a new decompressor, please update the analysis in 93 * ../header.S. 94 */ 95 96 static void scroll(void) 97 { 98 int i; 99 100 memmove(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2); 101 for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2) 102 vidmem[i] = ' '; 103 } 104 105 #define XMTRDY 0x20 106 107 #define TXR 0 /* Transmit register (WRITE) */ 108 #define LSR 5 /* Line Status */ 109 static void serial_putchar(int ch) 110 { 111 unsigned timeout = 0xffff; 112 113 while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout) 114 cpu_relax(); 115 116 outb(ch, early_serial_base + TXR); 117 } 118 119 void __putstr(const char *s) 120 { 121 int x, y, pos; 122 char c; 123 124 if (early_serial_base) { 125 const char *str = s; 126 while (*str) { 127 if (*str == '\n') 128 serial_putchar('\r'); 129 serial_putchar(*str++); 130 } 131 } 132 133 if (lines == 0 || cols == 0) 134 return; 135 136 x = boot_params_ptr->screen_info.orig_x; 137 y = boot_params_ptr->screen_info.orig_y; 138 139 while ((c = *s++) != '\0') { 140 if (c == '\n') { 141 x = 0; 142 if (++y >= lines) { 143 scroll(); 144 y--; 145 } 146 } else { 147 vidmem[(x + cols * y) * 2] = c; 148 if (++x >= cols) { 149 x = 0; 150 if (++y >= lines) { 151 scroll(); 152 y--; 153 } 154 } 155 } 156 } 157 158 boot_params_ptr->screen_info.orig_x = x; 159 boot_params_ptr->screen_info.orig_y = y; 160 161 pos = (x + cols * y) * 2; /* Update cursor position */ 162 outb(14, vidport); 163 outb(0xff & (pos >> 9), vidport+1); 164 outb(15, vidport); 165 outb(0xff & (pos >> 1), vidport+1); 166 } 167 168 static noinline void __putnum(unsigned long value, unsigned int base, 169 int mindig) 170 { 171 char buf[8*sizeof(value)+1]; 172 char *p; 173 174 p = buf + sizeof(buf); 175 *--p = '\0'; 176 177 while (mindig-- > 0 || value) { 178 unsigned char digit = value % base; 179 digit += (digit >= 10) ? ('a'-10) : '0'; 180 *--p = digit; 181 182 value /= base; 183 } 184 185 __putstr(p); 186 } 187 188 void __puthex(unsigned long value) 189 { 190 __putnum(value, 16, sizeof(value)*2); 191 } 192 193 void __putdec(unsigned long value) 194 { 195 __putnum(value, 10, 1); 196 } 197 198 #ifdef CONFIG_X86_NEED_RELOCS 199 static void handle_relocations(void *output, unsigned long output_len, 200 unsigned long virt_addr) 201 { 202 int *reloc; 203 unsigned long delta, map, ptr; 204 unsigned long min_addr = (unsigned long)output; 205 unsigned long max_addr = min_addr + (VO___bss_start - VO__text); 206 207 /* 208 * Calculate the delta between where vmlinux was linked to load 209 * and where it was actually loaded. 210 */ 211 delta = min_addr - LOAD_PHYSICAL_ADDR; 212 213 /* 214 * The kernel contains a table of relocation addresses. Those 215 * addresses have the final load address of the kernel in virtual 216 * memory. We are currently working in the self map. So we need to 217 * create an adjustment for kernel memory addresses to the self map. 218 * This will involve subtracting out the base address of the kernel. 219 */ 220 map = delta - __START_KERNEL_map; 221 222 /* 223 * 32-bit always performs relocations. 64-bit relocations are only 224 * needed if KASLR has chosen a different starting address offset 225 * from __START_KERNEL_map. 226 */ 227 if (IS_ENABLED(CONFIG_X86_64)) 228 delta = virt_addr - LOAD_PHYSICAL_ADDR; 229 230 if (!delta) { 231 debug_putstr("No relocation needed... "); 232 return; 233 } 234 debug_putstr("Performing relocations... "); 235 236 /* 237 * Process relocations: 32 bit relocations first then 64 bit after. 238 * Three sets of binary relocations are added to the end of the kernel 239 * before compression. Each relocation table entry is the kernel 240 * address of the location which needs to be updated stored as a 241 * 32-bit value which is sign extended to 64 bits. 242 * 243 * Format is: 244 * 245 * kernel bits... 246 * 0 - zero terminator for 64 bit relocations 247 * 64 bit relocation repeated 248 * 0 - zero terminator for inverse 32 bit relocations 249 * 32 bit inverse relocation repeated 250 * 0 - zero terminator for 32 bit relocations 251 * 32 bit relocation repeated 252 * 253 * So we work backwards from the end of the decompressed image. 254 */ 255 for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) { 256 long extended = *reloc; 257 extended += map; 258 259 ptr = (unsigned long)extended; 260 if (ptr < min_addr || ptr > max_addr) 261 error("32-bit relocation outside of kernel!\n"); 262 263 *(uint32_t *)ptr += delta; 264 } 265 #ifdef CONFIG_X86_64 266 while (*--reloc) { 267 long extended = *reloc; 268 extended += map; 269 270 ptr = (unsigned long)extended; 271 if (ptr < min_addr || ptr > max_addr) 272 error("inverse 32-bit relocation outside of kernel!\n"); 273 274 *(int32_t *)ptr -= delta; 275 } 276 for (reloc--; *reloc; reloc--) { 277 long extended = *reloc; 278 extended += map; 279 280 ptr = (unsigned long)extended; 281 if (ptr < min_addr || ptr > max_addr) 282 error("64-bit relocation outside of kernel!\n"); 283 284 *(uint64_t *)ptr += delta; 285 } 286 #endif 287 } 288 #else 289 static inline void handle_relocations(void *output, unsigned long output_len, 290 unsigned long virt_addr) 291 { } 292 #endif 293 294 static size_t parse_elf(void *output) 295 { 296 #ifdef CONFIG_X86_64 297 Elf64_Ehdr ehdr; 298 Elf64_Phdr *phdrs, *phdr; 299 #else 300 Elf32_Ehdr ehdr; 301 Elf32_Phdr *phdrs, *phdr; 302 #endif 303 void *dest; 304 int i; 305 306 memcpy(&ehdr, output, sizeof(ehdr)); 307 if (ehdr.e_ident[EI_MAG0] != ELFMAG0 || 308 ehdr.e_ident[EI_MAG1] != ELFMAG1 || 309 ehdr.e_ident[EI_MAG2] != ELFMAG2 || 310 ehdr.e_ident[EI_MAG3] != ELFMAG3) 311 error("Kernel is not a valid ELF file"); 312 313 debug_putstr("Parsing ELF... "); 314 315 phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum); 316 if (!phdrs) 317 error("Failed to allocate space for phdrs"); 318 319 memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum); 320 321 for (i = 0; i < ehdr.e_phnum; i++) { 322 phdr = &phdrs[i]; 323 324 switch (phdr->p_type) { 325 case PT_LOAD: 326 #ifdef CONFIG_X86_64 327 if ((phdr->p_align % 0x200000) != 0) 328 error("Alignment of LOAD segment isn't multiple of 2MB"); 329 #endif 330 #ifdef CONFIG_RELOCATABLE 331 dest = output; 332 dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR); 333 #else 334 dest = (void *)(phdr->p_paddr); 335 #endif 336 memmove(dest, output + phdr->p_offset, phdr->p_filesz); 337 break; 338 default: /* Ignore other PT_* */ break; 339 } 340 } 341 342 free(phdrs); 343 344 return ehdr.e_entry - LOAD_PHYSICAL_ADDR; 345 } 346 347 const unsigned long kernel_text_size = VO___start_rodata - VO__text; 348 const unsigned long kernel_total_size = VO__end - VO__text; 349 350 static u8 boot_heap[BOOT_HEAP_SIZE] __aligned(4); 351 352 extern unsigned char input_data[]; 353 extern unsigned int input_len, output_len; 354 355 unsigned long decompress_kernel(unsigned char *outbuf, unsigned long virt_addr, 356 void (*error)(char *x)) 357 { 358 unsigned long entry; 359 360 if (!free_mem_ptr) { 361 free_mem_ptr = (unsigned long)boot_heap; 362 free_mem_end_ptr = (unsigned long)boot_heap + sizeof(boot_heap); 363 } 364 365 if (__decompress(input_data, input_len, NULL, NULL, outbuf, output_len, 366 NULL, error) < 0) 367 return ULONG_MAX; 368 369 entry = parse_elf(outbuf); 370 handle_relocations(outbuf, output_len, virt_addr); 371 372 return entry; 373 } 374 375 /* 376 * Set the memory encryption xloadflag based on the mem_encrypt= command line 377 * parameter, if provided. 378 */ 379 static void parse_mem_encrypt(struct setup_header *hdr) 380 { 381 int on = cmdline_find_option_bool("mem_encrypt=on"); 382 int off = cmdline_find_option_bool("mem_encrypt=off"); 383 384 if (on > off) 385 hdr->xloadflags |= XLF_MEM_ENCRYPTION; 386 } 387 388 /* 389 * The compressed kernel image (ZO), has been moved so that its position 390 * is against the end of the buffer used to hold the uncompressed kernel 391 * image (VO) and the execution environment (.bss, .brk), which makes sure 392 * there is room to do the in-place decompression. (See header.S for the 393 * calculations.) 394 * 395 * |-----compressed kernel image------| 396 * V V 397 * 0 extract_offset +INIT_SIZE 398 * |-----------|---------------|-------------------------|--------| 399 * | | | | 400 * VO__text startup_32 of ZO VO__end ZO__end 401 * ^ ^ 402 * |-------uncompressed kernel image---------| 403 * 404 */ 405 asmlinkage __visible void *extract_kernel(void *rmode, unsigned char *output) 406 { 407 unsigned long virt_addr = LOAD_PHYSICAL_ADDR; 408 memptr heap = (memptr)boot_heap; 409 unsigned long needed_size; 410 size_t entry_offset; 411 412 /* Retain x86 boot parameters pointer passed from startup_32/64. */ 413 boot_params_ptr = rmode; 414 415 /* Clear flags intended for solely in-kernel use. */ 416 boot_params_ptr->hdr.loadflags &= ~KASLR_FLAG; 417 418 parse_mem_encrypt(&boot_params_ptr->hdr); 419 420 sanitize_boot_params(boot_params_ptr); 421 422 if (boot_params_ptr->screen_info.orig_video_mode == 7) { 423 vidmem = (char *) 0xb0000; 424 vidport = 0x3b4; 425 } else { 426 vidmem = (char *) 0xb8000; 427 vidport = 0x3d4; 428 } 429 430 lines = boot_params_ptr->screen_info.orig_video_lines; 431 cols = boot_params_ptr->screen_info.orig_video_cols; 432 433 init_default_io_ops(); 434 435 /* 436 * Detect TDX guest environment. 437 * 438 * It has to be done before console_init() in order to use 439 * paravirtualized port I/O operations if needed. 440 */ 441 early_tdx_detect(); 442 443 console_init(); 444 445 /* 446 * Save RSDP address for later use. Have this after console_init() 447 * so that early debugging output from the RSDP parsing code can be 448 * collected. 449 */ 450 boot_params_ptr->acpi_rsdp_addr = get_rsdp_addr(); 451 452 debug_putstr("early console in extract_kernel\n"); 453 454 free_mem_ptr = heap; /* Heap */ 455 free_mem_end_ptr = heap + BOOT_HEAP_SIZE; 456 457 /* 458 * The memory hole needed for the kernel is the larger of either 459 * the entire decompressed kernel plus relocation table, or the 460 * entire decompressed kernel plus .bss and .brk sections. 461 * 462 * On X86_64, the memory is mapped with PMD pages. Round the 463 * size up so that the full extent of PMD pages mapped is 464 * included in the check against the valid memory table 465 * entries. This ensures the full mapped area is usable RAM 466 * and doesn't include any reserved areas. 467 */ 468 needed_size = max_t(unsigned long, output_len, kernel_total_size); 469 #ifdef CONFIG_X86_64 470 needed_size = ALIGN(needed_size, MIN_KERNEL_ALIGN); 471 #endif 472 473 /* Report initial kernel position details. */ 474 debug_putaddr(input_data); 475 debug_putaddr(input_len); 476 debug_putaddr(output); 477 debug_putaddr(output_len); 478 debug_putaddr(kernel_total_size); 479 debug_putaddr(needed_size); 480 481 #ifdef CONFIG_X86_64 482 /* Report address of 32-bit trampoline */ 483 debug_putaddr(trampoline_32bit); 484 #endif 485 486 choose_random_location((unsigned long)input_data, input_len, 487 (unsigned long *)&output, 488 needed_size, 489 &virt_addr); 490 491 /* Validate memory location choices. */ 492 if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1)) 493 error("Destination physical address inappropriately aligned"); 494 if (virt_addr & (MIN_KERNEL_ALIGN - 1)) 495 error("Destination virtual address inappropriately aligned"); 496 #ifdef CONFIG_X86_64 497 if (heap > 0x3fffffffffffUL) 498 error("Destination address too large"); 499 if (virt_addr + needed_size > KERNEL_IMAGE_SIZE) 500 error("Destination virtual address is beyond the kernel mapping area"); 501 #else 502 if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff)) 503 error("Destination address too large"); 504 #endif 505 #ifndef CONFIG_RELOCATABLE 506 if (virt_addr != LOAD_PHYSICAL_ADDR) 507 error("Destination virtual address changed when not relocatable"); 508 #endif 509 510 debug_putstr("\nDecompressing Linux... "); 511 512 if (init_unaccepted_memory()) { 513 debug_putstr("Accepting memory... "); 514 accept_memory(__pa(output), __pa(output) + needed_size); 515 } 516 517 entry_offset = decompress_kernel(output, virt_addr, error); 518 519 debug_putstr("done.\nBooting the kernel (entry_offset: 0x"); 520 debug_puthex(entry_offset); 521 debug_putstr(").\n"); 522 523 /* Disable exception handling before booting the kernel */ 524 cleanup_exception_handling(); 525 526 if (spurious_nmi_count) { 527 error_putstr("Spurious early NMIs ignored: "); 528 error_putdec(spurious_nmi_count); 529 error_putstr("\n"); 530 } 531 532 return output + entry_offset; 533 } 534 535 void __fortify_panic(const u8 reason, size_t avail, size_t size) 536 { 537 error("detected buffer overflow"); 538 } 539