1 /* 2 * misc.c 3 * 4 * This is a collection of several routines from gzip-1.0.3 5 * adapted for Linux. 6 * 7 * malloc by Hannu Savolainen 1993 and Matthias Urlichs 1994 8 * puts by Nick Holloway 1993, better puts by Martin Mares 1995 9 * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996 10 */ 11 12 #include "misc.h" 13 #include "../string.h" 14 15 /* WARNING!! 16 * This code is compiled with -fPIC and it is relocated dynamically 17 * at run time, but no relocation processing is performed. 18 * This means that it is not safe to place pointers in static structures. 19 */ 20 21 /* 22 * Getting to provable safe in place decompression is hard. 23 * Worst case behaviours need to be analyzed. 24 * Background information: 25 * 26 * The file layout is: 27 * magic[2] 28 * method[1] 29 * flags[1] 30 * timestamp[4] 31 * extraflags[1] 32 * os[1] 33 * compressed data blocks[N] 34 * crc[4] orig_len[4] 35 * 36 * resulting in 18 bytes of non compressed data overhead. 37 * 38 * Files divided into blocks 39 * 1 bit (last block flag) 40 * 2 bits (block type) 41 * 42 * 1 block occurs every 32K -1 bytes or when there 50% compression 43 * has been achieved. The smallest block type encoding is always used. 44 * 45 * stored: 46 * 32 bits length in bytes. 47 * 48 * fixed: 49 * magic fixed tree. 50 * symbols. 51 * 52 * dynamic: 53 * dynamic tree encoding. 54 * symbols. 55 * 56 * 57 * The buffer for decompression in place is the length of the 58 * uncompressed data, plus a small amount extra to keep the algorithm safe. 59 * The compressed data is placed at the end of the buffer. The output 60 * pointer is placed at the start of the buffer and the input pointer 61 * is placed where the compressed data starts. Problems will occur 62 * when the output pointer overruns the input pointer. 63 * 64 * The output pointer can only overrun the input pointer if the input 65 * pointer is moving faster than the output pointer. A condition only 66 * triggered by data whose compressed form is larger than the uncompressed 67 * form. 68 * 69 * The worst case at the block level is a growth of the compressed data 70 * of 5 bytes per 32767 bytes. 71 * 72 * The worst case internal to a compressed block is very hard to figure. 73 * The worst case can at least be boundined by having one bit that represents 74 * 32764 bytes and then all of the rest of the bytes representing the very 75 * very last byte. 76 * 77 * All of which is enough to compute an amount of extra data that is required 78 * to be safe. To avoid problems at the block level allocating 5 extra bytes 79 * per 32767 bytes of data is sufficient. To avoind problems internal to a 80 * block adding an extra 32767 bytes (the worst case uncompressed block size) 81 * is sufficient, to ensure that in the worst case the decompressed data for 82 * block will stop the byte before the compressed data for a block begins. 83 * To avoid problems with the compressed data's meta information an extra 18 84 * bytes are needed. Leading to the formula: 85 * 86 * extra_bytes = (uncompressed_size >> 12) + 32768 + 18 + decompressor_size. 87 * 88 * Adding 8 bytes per 32K is a bit excessive but much easier to calculate. 89 * Adding 32768 instead of 32767 just makes for round numbers. 90 * Adding the decompressor_size is necessary as it musht live after all 91 * of the data as well. Last I measured the decompressor is about 14K. 92 * 10K of actual data and 4K of bss. 93 * 94 */ 95 96 /* 97 * gzip declarations 98 */ 99 #define STATIC static 100 101 #undef memcpy 102 103 /* 104 * Use a normal definition of memset() from string.c. There are already 105 * included header files which expect a definition of memset() and by 106 * the time we define memset macro, it is too late. 107 */ 108 #undef memset 109 #define memzero(s, n) memset((s), 0, (n)) 110 111 112 static void error(char *m); 113 114 /* 115 * This is set up by the setup-routine at boot-time 116 */ 117 struct boot_params *real_mode; /* Pointer to real-mode data */ 118 119 memptr free_mem_ptr; 120 memptr free_mem_end_ptr; 121 122 static char *vidmem; 123 static int vidport; 124 static int lines, cols; 125 126 #ifdef CONFIG_KERNEL_GZIP 127 #include "../../../../lib/decompress_inflate.c" 128 #endif 129 130 #ifdef CONFIG_KERNEL_BZIP2 131 #include "../../../../lib/decompress_bunzip2.c" 132 #endif 133 134 #ifdef CONFIG_KERNEL_LZMA 135 #include "../../../../lib/decompress_unlzma.c" 136 #endif 137 138 #ifdef CONFIG_KERNEL_XZ 139 #include "../../../../lib/decompress_unxz.c" 140 #endif 141 142 #ifdef CONFIG_KERNEL_LZO 143 #include "../../../../lib/decompress_unlzo.c" 144 #endif 145 146 #ifdef CONFIG_KERNEL_LZ4 147 #include "../../../../lib/decompress_unlz4.c" 148 #endif 149 150 static void scroll(void) 151 { 152 int i; 153 154 memcpy(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2); 155 for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2) 156 vidmem[i] = ' '; 157 } 158 159 #define XMTRDY 0x20 160 161 #define TXR 0 /* Transmit register (WRITE) */ 162 #define LSR 5 /* Line Status */ 163 static void serial_putchar(int ch) 164 { 165 unsigned timeout = 0xffff; 166 167 while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout) 168 cpu_relax(); 169 170 outb(ch, early_serial_base + TXR); 171 } 172 173 void __putstr(const char *s) 174 { 175 int x, y, pos; 176 char c; 177 178 if (early_serial_base) { 179 const char *str = s; 180 while (*str) { 181 if (*str == '\n') 182 serial_putchar('\r'); 183 serial_putchar(*str++); 184 } 185 } 186 187 if (real_mode->screen_info.orig_video_mode == 0 && 188 lines == 0 && cols == 0) 189 return; 190 191 x = real_mode->screen_info.orig_x; 192 y = real_mode->screen_info.orig_y; 193 194 while ((c = *s++) != '\0') { 195 if (c == '\n') { 196 x = 0; 197 if (++y >= lines) { 198 scroll(); 199 y--; 200 } 201 } else { 202 vidmem[(x + cols * y) * 2] = c; 203 if (++x >= cols) { 204 x = 0; 205 if (++y >= lines) { 206 scroll(); 207 y--; 208 } 209 } 210 } 211 } 212 213 real_mode->screen_info.orig_x = x; 214 real_mode->screen_info.orig_y = y; 215 216 pos = (x + cols * y) * 2; /* Update cursor position */ 217 outb(14, vidport); 218 outb(0xff & (pos >> 9), vidport+1); 219 outb(15, vidport); 220 outb(0xff & (pos >> 1), vidport+1); 221 } 222 223 static void error(char *x) 224 { 225 error_putstr("\n\n"); 226 error_putstr(x); 227 error_putstr("\n\n -- System halted"); 228 229 while (1) 230 asm("hlt"); 231 } 232 233 #if CONFIG_X86_NEED_RELOCS 234 static void handle_relocations(void *output, unsigned long output_len) 235 { 236 int *reloc; 237 unsigned long delta, map, ptr; 238 unsigned long min_addr = (unsigned long)output; 239 unsigned long max_addr = min_addr + output_len; 240 241 /* 242 * Calculate the delta between where vmlinux was linked to load 243 * and where it was actually loaded. 244 */ 245 delta = min_addr - LOAD_PHYSICAL_ADDR; 246 if (!delta) { 247 debug_putstr("No relocation needed... "); 248 return; 249 } 250 debug_putstr("Performing relocations... "); 251 252 /* 253 * The kernel contains a table of relocation addresses. Those 254 * addresses have the final load address of the kernel in virtual 255 * memory. We are currently working in the self map. So we need to 256 * create an adjustment for kernel memory addresses to the self map. 257 * This will involve subtracting out the base address of the kernel. 258 */ 259 map = delta - __START_KERNEL_map; 260 261 /* 262 * Process relocations: 32 bit relocations first then 64 bit after. 263 * Three sets of binary relocations are added to the end of the kernel 264 * before compression. Each relocation table entry is the kernel 265 * address of the location which needs to be updated stored as a 266 * 32-bit value which is sign extended to 64 bits. 267 * 268 * Format is: 269 * 270 * kernel bits... 271 * 0 - zero terminator for 64 bit relocations 272 * 64 bit relocation repeated 273 * 0 - zero terminator for inverse 32 bit relocations 274 * 32 bit inverse relocation repeated 275 * 0 - zero terminator for 32 bit relocations 276 * 32 bit relocation repeated 277 * 278 * So we work backwards from the end of the decompressed image. 279 */ 280 for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) { 281 int extended = *reloc; 282 extended += map; 283 284 ptr = (unsigned long)extended; 285 if (ptr < min_addr || ptr > max_addr) 286 error("32-bit relocation outside of kernel!\n"); 287 288 *(uint32_t *)ptr += delta; 289 } 290 #ifdef CONFIG_X86_64 291 while (*--reloc) { 292 long extended = *reloc; 293 extended += map; 294 295 ptr = (unsigned long)extended; 296 if (ptr < min_addr || ptr > max_addr) 297 error("inverse 32-bit relocation outside of kernel!\n"); 298 299 *(int32_t *)ptr -= delta; 300 } 301 for (reloc--; *reloc; reloc--) { 302 long extended = *reloc; 303 extended += map; 304 305 ptr = (unsigned long)extended; 306 if (ptr < min_addr || ptr > max_addr) 307 error("64-bit relocation outside of kernel!\n"); 308 309 *(uint64_t *)ptr += delta; 310 } 311 #endif 312 } 313 #else 314 static inline void handle_relocations(void *output, unsigned long output_len) 315 { } 316 #endif 317 318 static void parse_elf(void *output) 319 { 320 #ifdef CONFIG_X86_64 321 Elf64_Ehdr ehdr; 322 Elf64_Phdr *phdrs, *phdr; 323 #else 324 Elf32_Ehdr ehdr; 325 Elf32_Phdr *phdrs, *phdr; 326 #endif 327 void *dest; 328 int i; 329 330 memcpy(&ehdr, output, sizeof(ehdr)); 331 if (ehdr.e_ident[EI_MAG0] != ELFMAG0 || 332 ehdr.e_ident[EI_MAG1] != ELFMAG1 || 333 ehdr.e_ident[EI_MAG2] != ELFMAG2 || 334 ehdr.e_ident[EI_MAG3] != ELFMAG3) { 335 error("Kernel is not a valid ELF file"); 336 return; 337 } 338 339 debug_putstr("Parsing ELF... "); 340 341 phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum); 342 if (!phdrs) 343 error("Failed to allocate space for phdrs"); 344 345 memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum); 346 347 for (i = 0; i < ehdr.e_phnum; i++) { 348 phdr = &phdrs[i]; 349 350 switch (phdr->p_type) { 351 case PT_LOAD: 352 #ifdef CONFIG_RELOCATABLE 353 dest = output; 354 dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR); 355 #else 356 dest = (void *)(phdr->p_paddr); 357 #endif 358 memcpy(dest, 359 output + phdr->p_offset, 360 phdr->p_filesz); 361 break; 362 default: /* Ignore other PT_* */ break; 363 } 364 } 365 366 free(phdrs); 367 } 368 369 asmlinkage __visible void *decompress_kernel(void *rmode, memptr heap, 370 unsigned char *input_data, 371 unsigned long input_len, 372 unsigned char *output, 373 unsigned long output_len, 374 unsigned long run_size) 375 { 376 unsigned char *output_orig = output; 377 378 real_mode = rmode; 379 380 sanitize_boot_params(real_mode); 381 382 if (real_mode->screen_info.orig_video_mode == 7) { 383 vidmem = (char *) 0xb0000; 384 vidport = 0x3b4; 385 } else { 386 vidmem = (char *) 0xb8000; 387 vidport = 0x3d4; 388 } 389 390 lines = real_mode->screen_info.orig_video_lines; 391 cols = real_mode->screen_info.orig_video_cols; 392 393 console_init(); 394 debug_putstr("early console in decompress_kernel\n"); 395 396 free_mem_ptr = heap; /* Heap */ 397 free_mem_end_ptr = heap + BOOT_HEAP_SIZE; 398 399 /* 400 * The memory hole needed for the kernel is the larger of either 401 * the entire decompressed kernel plus relocation table, or the 402 * entire decompressed kernel plus .bss and .brk sections. 403 */ 404 output = choose_kernel_location(input_data, input_len, output, 405 output_len > run_size ? output_len 406 : run_size); 407 408 /* Validate memory location choices. */ 409 if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1)) 410 error("Destination address inappropriately aligned"); 411 #ifdef CONFIG_X86_64 412 if (heap > 0x3fffffffffffUL) 413 error("Destination address too large"); 414 #else 415 if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff)) 416 error("Destination address too large"); 417 #endif 418 #ifndef CONFIG_RELOCATABLE 419 if ((unsigned long)output != LOAD_PHYSICAL_ADDR) 420 error("Wrong destination address"); 421 #endif 422 423 debug_putstr("\nDecompressing Linux... "); 424 decompress(input_data, input_len, NULL, NULL, output, NULL, error); 425 parse_elf(output); 426 /* 427 * 32-bit always performs relocations. 64-bit relocations are only 428 * needed if kASLR has chosen a different load address. 429 */ 430 if (!IS_ENABLED(CONFIG_X86_64) || output != output_orig) 431 handle_relocations(output, output_len); 432 debug_putstr("done.\nBooting the kernel.\n"); 433 return output; 434 } 435