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