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 32 /* 33 * Use normal definitions of mem*() from string.c. There are already 34 * included header files which expect a definition of memset() and by 35 * the time we define memset macro, it is too late. 36 */ 37 #undef memcpy 38 #undef memset 39 #define memzero(s, n) memset((s), 0, (n)) 40 #define memmove memmove 41 42 /* Functions used by the included decompressor code below. */ 43 void *memmove(void *dest, const void *src, size_t n); 44 45 /* 46 * This is set up by the setup-routine at boot-time 47 */ 48 struct boot_params *boot_params; 49 50 memptr free_mem_ptr; 51 memptr free_mem_end_ptr; 52 53 static char *vidmem; 54 static int vidport; 55 static int lines, cols; 56 57 #ifdef CONFIG_KERNEL_GZIP 58 #include "../../../../lib/decompress_inflate.c" 59 #endif 60 61 #ifdef CONFIG_KERNEL_BZIP2 62 #include "../../../../lib/decompress_bunzip2.c" 63 #endif 64 65 #ifdef CONFIG_KERNEL_LZMA 66 #include "../../../../lib/decompress_unlzma.c" 67 #endif 68 69 #ifdef CONFIG_KERNEL_XZ 70 #include "../../../../lib/decompress_unxz.c" 71 #endif 72 73 #ifdef CONFIG_KERNEL_LZO 74 #include "../../../../lib/decompress_unlzo.c" 75 #endif 76 77 #ifdef CONFIG_KERNEL_LZ4 78 #include "../../../../lib/decompress_unlz4.c" 79 #endif 80 81 #ifdef CONFIG_KERNEL_ZSTD 82 #include "../../../../lib/decompress_unzstd.c" 83 #endif 84 /* 85 * NOTE: When adding a new decompressor, please update the analysis in 86 * ../header.S. 87 */ 88 89 static void scroll(void) 90 { 91 int i; 92 93 memmove(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2); 94 for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2) 95 vidmem[i] = ' '; 96 } 97 98 #define XMTRDY 0x20 99 100 #define TXR 0 /* Transmit register (WRITE) */ 101 #define LSR 5 /* Line Status */ 102 static void serial_putchar(int ch) 103 { 104 unsigned timeout = 0xffff; 105 106 while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout) 107 cpu_relax(); 108 109 outb(ch, early_serial_base + TXR); 110 } 111 112 void __putstr(const char *s) 113 { 114 int x, y, pos; 115 char c; 116 117 if (early_serial_base) { 118 const char *str = s; 119 while (*str) { 120 if (*str == '\n') 121 serial_putchar('\r'); 122 serial_putchar(*str++); 123 } 124 } 125 126 if (lines == 0 || cols == 0) 127 return; 128 129 x = boot_params->screen_info.orig_x; 130 y = boot_params->screen_info.orig_y; 131 132 while ((c = *s++) != '\0') { 133 if (c == '\n') { 134 x = 0; 135 if (++y >= lines) { 136 scroll(); 137 y--; 138 } 139 } else { 140 vidmem[(x + cols * y) * 2] = c; 141 if (++x >= cols) { 142 x = 0; 143 if (++y >= lines) { 144 scroll(); 145 y--; 146 } 147 } 148 } 149 } 150 151 boot_params->screen_info.orig_x = x; 152 boot_params->screen_info.orig_y = y; 153 154 pos = (x + cols * y) * 2; /* Update cursor position */ 155 outb(14, vidport); 156 outb(0xff & (pos >> 9), vidport+1); 157 outb(15, vidport); 158 outb(0xff & (pos >> 1), vidport+1); 159 } 160 161 void __puthex(unsigned long value) 162 { 163 char alpha[2] = "0"; 164 int bits; 165 166 for (bits = sizeof(value) * 8 - 4; bits >= 0; bits -= 4) { 167 unsigned long digit = (value >> bits) & 0xf; 168 169 if (digit < 0xA) 170 alpha[0] = '0' + digit; 171 else 172 alpha[0] = 'a' + (digit - 0xA); 173 174 __putstr(alpha); 175 } 176 } 177 178 #if CONFIG_X86_NEED_RELOCS 179 static void handle_relocations(void *output, unsigned long output_len, 180 unsigned long virt_addr) 181 { 182 int *reloc; 183 unsigned long delta, map, ptr; 184 unsigned long min_addr = (unsigned long)output; 185 unsigned long max_addr = min_addr + (VO___bss_start - VO__text); 186 187 /* 188 * Calculate the delta between where vmlinux was linked to load 189 * and where it was actually loaded. 190 */ 191 delta = min_addr - LOAD_PHYSICAL_ADDR; 192 193 /* 194 * The kernel contains a table of relocation addresses. Those 195 * addresses have the final load address of the kernel in virtual 196 * memory. We are currently working in the self map. So we need to 197 * create an adjustment for kernel memory addresses to the self map. 198 * This will involve subtracting out the base address of the kernel. 199 */ 200 map = delta - __START_KERNEL_map; 201 202 /* 203 * 32-bit always performs relocations. 64-bit relocations are only 204 * needed if KASLR has chosen a different starting address offset 205 * from __START_KERNEL_map. 206 */ 207 if (IS_ENABLED(CONFIG_X86_64)) 208 delta = virt_addr - LOAD_PHYSICAL_ADDR; 209 210 if (!delta) { 211 debug_putstr("No relocation needed... "); 212 return; 213 } 214 debug_putstr("Performing relocations... "); 215 216 /* 217 * Process relocations: 32 bit relocations first then 64 bit after. 218 * Three sets of binary relocations are added to the end of the kernel 219 * before compression. Each relocation table entry is the kernel 220 * address of the location which needs to be updated stored as a 221 * 32-bit value which is sign extended to 64 bits. 222 * 223 * Format is: 224 * 225 * kernel bits... 226 * 0 - zero terminator for 64 bit relocations 227 * 64 bit relocation repeated 228 * 0 - zero terminator for inverse 32 bit relocations 229 * 32 bit inverse relocation repeated 230 * 0 - zero terminator for 32 bit relocations 231 * 32 bit relocation repeated 232 * 233 * So we work backwards from the end of the decompressed image. 234 */ 235 for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) { 236 long extended = *reloc; 237 extended += map; 238 239 ptr = (unsigned long)extended; 240 if (ptr < min_addr || ptr > max_addr) 241 error("32-bit relocation outside of kernel!\n"); 242 243 *(uint32_t *)ptr += delta; 244 } 245 #ifdef CONFIG_X86_64 246 while (*--reloc) { 247 long extended = *reloc; 248 extended += map; 249 250 ptr = (unsigned long)extended; 251 if (ptr < min_addr || ptr > max_addr) 252 error("inverse 32-bit relocation outside of kernel!\n"); 253 254 *(int32_t *)ptr -= delta; 255 } 256 for (reloc--; *reloc; reloc--) { 257 long extended = *reloc; 258 extended += map; 259 260 ptr = (unsigned long)extended; 261 if (ptr < min_addr || ptr > max_addr) 262 error("64-bit relocation outside of kernel!\n"); 263 264 *(uint64_t *)ptr += delta; 265 } 266 #endif 267 } 268 #else 269 static inline void handle_relocations(void *output, unsigned long output_len, 270 unsigned long virt_addr) 271 { } 272 #endif 273 274 static void parse_elf(void *output) 275 { 276 #ifdef CONFIG_X86_64 277 Elf64_Ehdr ehdr; 278 Elf64_Phdr *phdrs, *phdr; 279 #else 280 Elf32_Ehdr ehdr; 281 Elf32_Phdr *phdrs, *phdr; 282 #endif 283 void *dest; 284 int i; 285 286 memcpy(&ehdr, output, sizeof(ehdr)); 287 if (ehdr.e_ident[EI_MAG0] != ELFMAG0 || 288 ehdr.e_ident[EI_MAG1] != ELFMAG1 || 289 ehdr.e_ident[EI_MAG2] != ELFMAG2 || 290 ehdr.e_ident[EI_MAG3] != ELFMAG3) { 291 error("Kernel is not a valid ELF file"); 292 return; 293 } 294 295 debug_putstr("Parsing ELF... "); 296 297 phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum); 298 if (!phdrs) 299 error("Failed to allocate space for phdrs"); 300 301 memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum); 302 303 for (i = 0; i < ehdr.e_phnum; i++) { 304 phdr = &phdrs[i]; 305 306 switch (phdr->p_type) { 307 case PT_LOAD: 308 #ifdef CONFIG_X86_64 309 if ((phdr->p_align % 0x200000) != 0) 310 error("Alignment of LOAD segment isn't multiple of 2MB"); 311 #endif 312 #ifdef CONFIG_RELOCATABLE 313 dest = output; 314 dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR); 315 #else 316 dest = (void *)(phdr->p_paddr); 317 #endif 318 memmove(dest, output + phdr->p_offset, phdr->p_filesz); 319 break; 320 default: /* Ignore other PT_* */ break; 321 } 322 } 323 324 free(phdrs); 325 } 326 327 /* 328 * The compressed kernel image (ZO), has been moved so that its position 329 * is against the end of the buffer used to hold the uncompressed kernel 330 * image (VO) and the execution environment (.bss, .brk), which makes sure 331 * there is room to do the in-place decompression. (See header.S for the 332 * calculations.) 333 * 334 * |-----compressed kernel image------| 335 * V V 336 * 0 extract_offset +INIT_SIZE 337 * |-----------|---------------|-------------------------|--------| 338 * | | | | 339 * VO__text startup_32 of ZO VO__end ZO__end 340 * ^ ^ 341 * |-------uncompressed kernel image---------| 342 * 343 */ 344 asmlinkage __visible void *extract_kernel(void *rmode, memptr heap, 345 unsigned char *input_data, 346 unsigned long input_len, 347 unsigned char *output, 348 unsigned long output_len) 349 { 350 const unsigned long kernel_total_size = VO__end - VO__text; 351 unsigned long virt_addr = LOAD_PHYSICAL_ADDR; 352 unsigned long needed_size; 353 354 /* Retain x86 boot parameters pointer passed from startup_32/64. */ 355 boot_params = rmode; 356 357 /* Clear flags intended for solely in-kernel use. */ 358 boot_params->hdr.loadflags &= ~KASLR_FLAG; 359 360 sanitize_boot_params(boot_params); 361 362 if (boot_params->screen_info.orig_video_mode == 7) { 363 vidmem = (char *) 0xb0000; 364 vidport = 0x3b4; 365 } else { 366 vidmem = (char *) 0xb8000; 367 vidport = 0x3d4; 368 } 369 370 lines = boot_params->screen_info.orig_video_lines; 371 cols = boot_params->screen_info.orig_video_cols; 372 373 console_init(); 374 375 /* 376 * Save RSDP address for later use. Have this after console_init() 377 * so that early debugging output from the RSDP parsing code can be 378 * collected. 379 */ 380 boot_params->acpi_rsdp_addr = get_rsdp_addr(); 381 382 debug_putstr("early console in extract_kernel\n"); 383 384 free_mem_ptr = heap; /* Heap */ 385 free_mem_end_ptr = heap + BOOT_HEAP_SIZE; 386 387 /* 388 * The memory hole needed for the kernel is the larger of either 389 * the entire decompressed kernel plus relocation table, or the 390 * entire decompressed kernel plus .bss and .brk sections. 391 * 392 * On X86_64, the memory is mapped with PMD pages. Round the 393 * size up so that the full extent of PMD pages mapped is 394 * included in the check against the valid memory table 395 * entries. This ensures the full mapped area is usable RAM 396 * and doesn't include any reserved areas. 397 */ 398 needed_size = max(output_len, kernel_total_size); 399 #ifdef CONFIG_X86_64 400 needed_size = ALIGN(needed_size, MIN_KERNEL_ALIGN); 401 #endif 402 403 /* Report initial kernel position details. */ 404 debug_putaddr(input_data); 405 debug_putaddr(input_len); 406 debug_putaddr(output); 407 debug_putaddr(output_len); 408 debug_putaddr(kernel_total_size); 409 debug_putaddr(needed_size); 410 411 #ifdef CONFIG_X86_64 412 /* Report address of 32-bit trampoline */ 413 debug_putaddr(trampoline_32bit); 414 #endif 415 416 choose_random_location((unsigned long)input_data, input_len, 417 (unsigned long *)&output, 418 needed_size, 419 &virt_addr); 420 421 /* Validate memory location choices. */ 422 if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1)) 423 error("Destination physical address inappropriately aligned"); 424 if (virt_addr & (MIN_KERNEL_ALIGN - 1)) 425 error("Destination virtual address inappropriately aligned"); 426 #ifdef CONFIG_X86_64 427 if (heap > 0x3fffffffffffUL) 428 error("Destination address too large"); 429 if (virt_addr + max(output_len, kernel_total_size) > KERNEL_IMAGE_SIZE) 430 error("Destination virtual address is beyond the kernel mapping area"); 431 #else 432 if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff)) 433 error("Destination address too large"); 434 #endif 435 #ifndef CONFIG_RELOCATABLE 436 if ((unsigned long)output != LOAD_PHYSICAL_ADDR) 437 error("Destination address does not match LOAD_PHYSICAL_ADDR"); 438 if (virt_addr != LOAD_PHYSICAL_ADDR) 439 error("Destination virtual address changed when not relocatable"); 440 #endif 441 442 debug_putstr("\nDecompressing Linux... "); 443 __decompress(input_data, input_len, NULL, NULL, output, output_len, 444 NULL, error); 445 parse_elf(output); 446 handle_relocations(output, output_len, virt_addr); 447 debug_putstr("done.\nBooting the kernel.\n"); 448 return output; 449 } 450 451 void fortify_panic(const char *name) 452 { 453 error("detected buffer overflow"); 454 } 455