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