1 /* 2 * misc.c 3 * 4 * This is a collection of several routines used to extract the kernel 5 * which includes KASLR relocation, decompression, ELF parsing, and 6 * relocation processing. Additionally included are the screen and serial 7 * output functions and related debugging support functions. 8 * 9 * malloc by Hannu Savolainen 1993 and Matthias Urlichs 1994 10 * puts by Nick Holloway 1993, better puts by Martin Mares 1995 11 * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996 12 */ 13 14 #include "misc.h" 15 #include "error.h" 16 #include "../string.h" 17 #include "../voffset.h" 18 19 /* 20 * WARNING!! 21 * This code is compiled with -fPIC and it is relocated dynamically at 22 * run time, but no relocation processing is performed. This means that 23 * it is not safe to place pointers in static structures. 24 */ 25 26 /* Macros used by the included decompressor code below. */ 27 #define STATIC static 28 29 /* 30 * Use normal definitions of mem*() from string.c. There are already 31 * included header files which expect a definition of memset() and by 32 * the time we define memset macro, it is too late. 33 */ 34 #undef memcpy 35 #undef memset 36 #define memzero(s, n) memset((s), 0, (n)) 37 #define memmove memmove 38 39 /* Functions used by the included decompressor code below. */ 40 void *memmove(void *dest, const void *src, size_t n); 41 42 /* 43 * This is set up by the setup-routine at boot-time 44 */ 45 struct boot_params *boot_params; 46 47 memptr free_mem_ptr; 48 memptr free_mem_end_ptr; 49 50 static char *vidmem; 51 static int vidport; 52 static int lines, cols; 53 54 #ifdef CONFIG_KERNEL_GZIP 55 #include "../../../../lib/decompress_inflate.c" 56 #endif 57 58 #ifdef CONFIG_KERNEL_BZIP2 59 #include "../../../../lib/decompress_bunzip2.c" 60 #endif 61 62 #ifdef CONFIG_KERNEL_LZMA 63 #include "../../../../lib/decompress_unlzma.c" 64 #endif 65 66 #ifdef CONFIG_KERNEL_XZ 67 #include "../../../../lib/decompress_unxz.c" 68 #endif 69 70 #ifdef CONFIG_KERNEL_LZO 71 #include "../../../../lib/decompress_unlzo.c" 72 #endif 73 74 #ifdef CONFIG_KERNEL_LZ4 75 #include "../../../../lib/decompress_unlz4.c" 76 #endif 77 /* 78 * NOTE: When adding a new decompressor, please update the analysis in 79 * ../header.S. 80 */ 81 82 static void scroll(void) 83 { 84 int i; 85 86 memmove(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2); 87 for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2) 88 vidmem[i] = ' '; 89 } 90 91 #define XMTRDY 0x20 92 93 #define TXR 0 /* Transmit register (WRITE) */ 94 #define LSR 5 /* Line Status */ 95 static void serial_putchar(int ch) 96 { 97 unsigned timeout = 0xffff; 98 99 while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout) 100 cpu_relax(); 101 102 outb(ch, early_serial_base + TXR); 103 } 104 105 void __putstr(const char *s) 106 { 107 int x, y, pos; 108 char c; 109 110 if (early_serial_base) { 111 const char *str = s; 112 while (*str) { 113 if (*str == '\n') 114 serial_putchar('\r'); 115 serial_putchar(*str++); 116 } 117 } 118 119 if (boot_params->screen_info.orig_video_mode == 0 && 120 lines == 0 && cols == 0) 121 return; 122 123 x = boot_params->screen_info.orig_x; 124 y = boot_params->screen_info.orig_y; 125 126 while ((c = *s++) != '\0') { 127 if (c == '\n') { 128 x = 0; 129 if (++y >= lines) { 130 scroll(); 131 y--; 132 } 133 } else { 134 vidmem[(x + cols * y) * 2] = c; 135 if (++x >= cols) { 136 x = 0; 137 if (++y >= lines) { 138 scroll(); 139 y--; 140 } 141 } 142 } 143 } 144 145 boot_params->screen_info.orig_x = x; 146 boot_params->screen_info.orig_y = y; 147 148 pos = (x + cols * y) * 2; /* Update cursor position */ 149 outb(14, vidport); 150 outb(0xff & (pos >> 9), vidport+1); 151 outb(15, vidport); 152 outb(0xff & (pos >> 1), vidport+1); 153 } 154 155 void __puthex(unsigned long value) 156 { 157 char alpha[2] = "0"; 158 int bits; 159 160 for (bits = sizeof(value) * 8 - 4; bits >= 0; bits -= 4) { 161 unsigned long digit = (value >> bits) & 0xf; 162 163 if (digit < 0xA) 164 alpha[0] = '0' + digit; 165 else 166 alpha[0] = 'a' + (digit - 0xA); 167 168 __putstr(alpha); 169 } 170 } 171 172 #if CONFIG_X86_NEED_RELOCS 173 static void handle_relocations(void *output, unsigned long output_len, 174 unsigned long virt_addr) 175 { 176 int *reloc; 177 unsigned long delta, map, ptr; 178 unsigned long min_addr = (unsigned long)output; 179 unsigned long max_addr = min_addr + (VO___bss_start - VO__text); 180 181 /* 182 * Calculate the delta between where vmlinux was linked to load 183 * and where it was actually loaded. 184 */ 185 delta = min_addr - LOAD_PHYSICAL_ADDR; 186 187 /* 188 * The kernel contains a table of relocation addresses. Those 189 * addresses have the final load address of the kernel in virtual 190 * memory. We are currently working in the self map. So we need to 191 * create an adjustment for kernel memory addresses to the self map. 192 * This will involve subtracting out the base address of the kernel. 193 */ 194 map = delta - __START_KERNEL_map; 195 196 /* 197 * 32-bit always performs relocations. 64-bit relocations are only 198 * needed if KASLR has chosen a different starting address offset 199 * from __START_KERNEL_map. 200 */ 201 if (IS_ENABLED(CONFIG_X86_64)) 202 delta = virt_addr - LOAD_PHYSICAL_ADDR; 203 204 if (!delta) { 205 debug_putstr("No relocation needed... "); 206 return; 207 } 208 debug_putstr("Performing relocations... "); 209 210 /* 211 * Process relocations: 32 bit relocations first then 64 bit after. 212 * Three sets of binary relocations are added to the end of the kernel 213 * before compression. Each relocation table entry is the kernel 214 * address of the location which needs to be updated stored as a 215 * 32-bit value which is sign extended to 64 bits. 216 * 217 * Format is: 218 * 219 * kernel bits... 220 * 0 - zero terminator for 64 bit relocations 221 * 64 bit relocation repeated 222 * 0 - zero terminator for inverse 32 bit relocations 223 * 32 bit inverse relocation repeated 224 * 0 - zero terminator for 32 bit relocations 225 * 32 bit relocation repeated 226 * 227 * So we work backwards from the end of the decompressed image. 228 */ 229 for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) { 230 long extended = *reloc; 231 extended += map; 232 233 ptr = (unsigned long)extended; 234 if (ptr < min_addr || ptr > max_addr) 235 error("32-bit relocation outside of kernel!\n"); 236 237 *(uint32_t *)ptr += delta; 238 } 239 #ifdef CONFIG_X86_64 240 while (*--reloc) { 241 long extended = *reloc; 242 extended += map; 243 244 ptr = (unsigned long)extended; 245 if (ptr < min_addr || ptr > max_addr) 246 error("inverse 32-bit relocation outside of kernel!\n"); 247 248 *(int32_t *)ptr -= delta; 249 } 250 for (reloc--; *reloc; reloc--) { 251 long extended = *reloc; 252 extended += map; 253 254 ptr = (unsigned long)extended; 255 if (ptr < min_addr || ptr > max_addr) 256 error("64-bit relocation outside of kernel!\n"); 257 258 *(uint64_t *)ptr += delta; 259 } 260 #endif 261 } 262 #else 263 static inline void handle_relocations(void *output, unsigned long output_len, 264 unsigned long virt_addr) 265 { } 266 #endif 267 268 static void parse_elf(void *output) 269 { 270 #ifdef CONFIG_X86_64 271 Elf64_Ehdr ehdr; 272 Elf64_Phdr *phdrs, *phdr; 273 #else 274 Elf32_Ehdr ehdr; 275 Elf32_Phdr *phdrs, *phdr; 276 #endif 277 void *dest; 278 int i; 279 280 memcpy(&ehdr, output, sizeof(ehdr)); 281 if (ehdr.e_ident[EI_MAG0] != ELFMAG0 || 282 ehdr.e_ident[EI_MAG1] != ELFMAG1 || 283 ehdr.e_ident[EI_MAG2] != ELFMAG2 || 284 ehdr.e_ident[EI_MAG3] != ELFMAG3) { 285 error("Kernel is not a valid ELF file"); 286 return; 287 } 288 289 debug_putstr("Parsing ELF... "); 290 291 phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum); 292 if (!phdrs) 293 error("Failed to allocate space for phdrs"); 294 295 memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum); 296 297 for (i = 0; i < ehdr.e_phnum; i++) { 298 phdr = &phdrs[i]; 299 300 switch (phdr->p_type) { 301 case PT_LOAD: 302 #ifdef CONFIG_RELOCATABLE 303 dest = output; 304 dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR); 305 #else 306 dest = (void *)(phdr->p_paddr); 307 #endif 308 memmove(dest, output + phdr->p_offset, phdr->p_filesz); 309 break; 310 default: /* Ignore other PT_* */ break; 311 } 312 } 313 314 free(phdrs); 315 } 316 317 /* 318 * The compressed kernel image (ZO), has been moved so that its position 319 * is against the end of the buffer used to hold the uncompressed kernel 320 * image (VO) and the execution environment (.bss, .brk), which makes sure 321 * there is room to do the in-place decompression. (See header.S for the 322 * calculations.) 323 * 324 * |-----compressed kernel image------| 325 * V V 326 * 0 extract_offset +INIT_SIZE 327 * |-----------|---------------|-------------------------|--------| 328 * | | | | 329 * VO__text startup_32 of ZO VO__end ZO__end 330 * ^ ^ 331 * |-------uncompressed kernel image---------| 332 * 333 */ 334 asmlinkage __visible void *extract_kernel(void *rmode, memptr heap, 335 unsigned char *input_data, 336 unsigned long input_len, 337 unsigned char *output, 338 unsigned long output_len) 339 { 340 const unsigned long kernel_total_size = VO__end - VO__text; 341 unsigned long virt_addr = (unsigned long)output; 342 343 /* Retain x86 boot parameters pointer passed from startup_32/64. */ 344 boot_params = rmode; 345 346 /* Clear flags intended for solely in-kernel use. */ 347 boot_params->hdr.loadflags &= ~KASLR_FLAG; 348 349 sanitize_boot_params(boot_params); 350 351 if (boot_params->screen_info.orig_video_mode == 7) { 352 vidmem = (char *) 0xb0000; 353 vidport = 0x3b4; 354 } else { 355 vidmem = (char *) 0xb8000; 356 vidport = 0x3d4; 357 } 358 359 lines = boot_params->screen_info.orig_video_lines; 360 cols = boot_params->screen_info.orig_video_cols; 361 362 console_init(); 363 debug_putstr("early console in extract_kernel\n"); 364 365 free_mem_ptr = heap; /* Heap */ 366 free_mem_end_ptr = heap + BOOT_HEAP_SIZE; 367 368 /* Report initial kernel position details. */ 369 debug_putaddr(input_data); 370 debug_putaddr(input_len); 371 debug_putaddr(output); 372 debug_putaddr(output_len); 373 debug_putaddr(kernel_total_size); 374 375 /* 376 * The memory hole needed for the kernel is the larger of either 377 * the entire decompressed kernel plus relocation table, or the 378 * entire decompressed kernel plus .bss and .brk sections. 379 */ 380 choose_random_location((unsigned long)input_data, input_len, 381 (unsigned long *)&output, 382 max(output_len, kernel_total_size), 383 &virt_addr); 384 385 /* Validate memory location choices. */ 386 if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1)) 387 error("Destination physical address inappropriately aligned"); 388 if (virt_addr & (MIN_KERNEL_ALIGN - 1)) 389 error("Destination virtual address inappropriately aligned"); 390 #ifdef CONFIG_X86_64 391 if (heap > 0x3fffffffffffUL) 392 error("Destination address too large"); 393 #else 394 if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff)) 395 error("Destination address too large"); 396 #endif 397 #ifndef CONFIG_RELOCATABLE 398 if ((unsigned long)output != LOAD_PHYSICAL_ADDR) 399 error("Destination address does not match LOAD_PHYSICAL_ADDR"); 400 if ((unsigned long)output != virt_addr) 401 error("Destination virtual address changed when not relocatable"); 402 #endif 403 404 debug_putstr("\nDecompressing Linux... "); 405 __decompress(input_data, input_len, NULL, NULL, output, output_len, 406 NULL, error); 407 parse_elf(output); 408 handle_relocations(output, output_len, virt_addr); 409 debug_putstr("done.\nBooting the kernel.\n"); 410 return output; 411 } 412