arch/x86/boot/compressed/misc.c

   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
  14 /* WARNING!!
  15  * This code is compiled with -fPIC and it is relocated dynamically
  16  * at run time, but no relocation processing is performed.
  17  * This means that it is not safe to place pointers in static structures.
  18  */
  19
  20 /*
  21  * Getting to provable safe in place decompression is hard.
  22  * Worst case behaviours need to be analyzed.
  23  * Background information:
  24  *
  25  * The file layout is:
  26  *    magic[2]
  27  *    method[1]
  28  *    flags[1]
  29  *    timestamp[4]
  30  *    extraflags[1]
  31  *    os[1]
  32  *    compressed data blocks[N]
  33  *    crc[4] orig_len[4]
  34  *
  35  * resulting in 18 bytes of non compressed data overhead.
  36  *
  37  * Files divided into blocks
  38  * 1 bit (last block flag)
  39  * 2 bits (block type)
  40  *
  41  * 1 block occurs every 32K -1 bytes or when there 50% compression
  42  * has been achieved. The smallest block type encoding is always used.
  43  *
  44  * stored:
  45  *    32 bits length in bytes.
  46  *
  47  * fixed:
  48  *    magic fixed tree.
  49  *    symbols.
  50  *
  51  * dynamic:
  52  *    dynamic tree encoding.
  53  *    symbols.
  54  *
  55  *
  56  * The buffer for decompression in place is the length of the
  57  * uncompressed data, plus a small amount extra to keep the algorithm safe.
  58  * The compressed data is placed at the end of the buffer.  The output
  59  * pointer is placed at the start of the buffer and the input pointer
  60  * is placed where the compressed data starts.  Problems will occur
  61  * when the output pointer overruns the input pointer.
  62  *
  63  * The output pointer can only overrun the input pointer if the input
  64  * pointer is moving faster than the output pointer.  A condition only
  65  * triggered by data whose compressed form is larger than the uncompressed
  66  * form.
  67  *
  68  * The worst case at the block level is a growth of the compressed data
  69  * of 5 bytes per 32767 bytes.
  70  *
  71  * The worst case internal to a compressed block is very hard to figure.
  72  * The worst case can at least be boundined by having one bit that represents
  73  * 32764 bytes and then all of the rest of the bytes representing the very
  74  * very last byte.
  75  *
  76  * All of which is enough to compute an amount of extra data that is required
  77  * to be safe.  To avoid problems at the block level allocating 5 extra bytes
  78  * per 32767 bytes of data is sufficient.  To avoind problems internal to a
  79  * block adding an extra 32767 bytes (the worst case uncompressed block size)
  80  * is sufficient, to ensure that in the worst case the decompressed data for
  81  * block will stop the byte before the compressed data for a block begins.
  82  * To avoid problems with the compressed data's meta information an extra 18
  83  * bytes are needed.  Leading to the formula:
  84  *
  85  * extra_bytes = (uncompressed_size >> 12) + 32768 + 18 + decompressor_size.
  86  *
  87  * Adding 8 bytes per 32K is a bit excessive but much easier to calculate.
  88  * Adding 32768 instead of 32767 just makes for round numbers.
  89  * Adding the decompressor_size is necessary as it musht live after all
  90  * of the data as well.  Last I measured the decompressor is about 14K.
  91  * 10K of actual data and 4K of bss.
  92  *
  93  */
  94
  95 /*
  96  * gzip declarations
  97  */
  98 #define STATIC          static
  99
 100 #undef memset
 101 #undef memcpy
 102 #define memzero(s, n)   memset((s), 0, (n))
 103
 104
 105 static void error(char *m);
 106
 107 /*
 108  * This is set up by the setup-routine at boot-time
 109  */
 110 struct boot_params *real_mode;          /* Pointer to real-mode data */
 111
 112 void *memset(void *s, int c, size_t n);
 113 void *memcpy(void *dest, const void *src, size_t n);
 114
 115 #ifdef CONFIG_X86_64
 116 #define memptr long
 117 #else
 118 #define memptr unsigned
 119 #endif
 120
 121 static memptr free_mem_ptr;
 122 static memptr free_mem_end_ptr;
 123
 124 static char *vidmem;
 125 static int vidport;
 126 static int lines, cols;
 127
 128 #ifdef CONFIG_KERNEL_GZIP
 129 #include "../../../../lib/decompress_inflate.c"
 130 #endif
 131
 132 #ifdef CONFIG_KERNEL_BZIP2
 133 #include "../../../../lib/decompress_bunzip2.c"
 134 #endif
 135
 136 #ifdef CONFIG_KERNEL_LZMA
 137 #include "../../../../lib/decompress_unlzma.c"
 138 #endif
 139
 140 #ifdef CONFIG_KERNEL_XZ
 141 #include "../../../../lib/decompress_unxz.c"
 142 #endif
 143
 144 #ifdef CONFIG_KERNEL_LZO
 145 #include "../../../../lib/decompress_unlzo.c"
 146 #endif
 147
 148 #ifdef CONFIG_KERNEL_LZ4
 149 #include "../../../../lib/decompress_unlz4.c"
 150 #endif
 151
 152 static void scroll(void)
 153 {
 154         int i;
 155
 156         memcpy(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
 157         for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
 158                 vidmem[i] = ' ';
 159 }
 160
 161 #define XMTRDY          0x20
 162
 163 #define TXR             0       /*  Transmit register (WRITE) */
 164 #define LSR             5       /*  Line Status               */
 165 static void serial_putchar(int ch)
 166 {
 167         unsigned timeout = 0xffff;
 168
 169         while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
 170                 cpu_relax();
 171
 172         outb(ch, early_serial_base + TXR);
 173 }
 174
 175 void __putstr(const char *s)
 176 {
 177         int x, y, pos;
 178         char c;
 179
 180         if (early_serial_base) {
 181                 const char *str = s;
 182                 while (*str) {
 183                         if (*str == '\n')
 184                                 serial_putchar('\r');
 185                         serial_putchar(*str++);
 186                 }
 187         }
 188
 189         if (real_mode->screen_info.orig_video_mode == 0 &&
 190             lines == 0 && cols == 0)
 191                 return;
 192
 193         x = real_mode->screen_info.orig_x;
 194         y = real_mode->screen_info.orig_y;
 195
 196         while ((c = *s++) != '\0') {
 197                 if (c == '\n') {
 198                         x = 0;
 199                         if (++y >= lines) {
 200                                 scroll();
 201                                 y--;
 202                         }
 203                 } else {
 204                         vidmem[(x + cols * y) * 2] = c;
 205                         if (++x >= cols) {
 206                                 x = 0;
 207                                 if (++y >= lines) {
 208                                         scroll();
 209                                         y--;
 210                                 }
 211                         }
 212                 }
 213         }
 214
 215         real_mode->screen_info.orig_x = x;
 216         real_mode->screen_info.orig_y = y;
 217
 218         pos = (x + cols * y) * 2;       /* Update cursor position */
 219         outb(14, vidport);
 220         outb(0xff & (pos >> 9), vidport+1);
 221         outb(15, vidport);
 222         outb(0xff & (pos >> 1), vidport+1);
 223 }
 224
 225 void *memset(void *s, int c, size_t n)
 226 {
 227         int i;
 228         char *ss = s;
 229
 230         for (i = 0; i < n; i++)
 231                 ss[i] = c;
 232         return s;
 233 }
 234 #ifdef CONFIG_X86_32
 235 void *memcpy(void *dest, const void *src, size_t n)
 236 {
 237         int d0, d1, d2;
 238         asm volatile(
 239                 "rep ; movsl\n\t"
 240                 "movl %4,%%ecx\n\t"
 241                 "rep ; movsb\n\t"
 242                 : "=&c" (d0), "=&D" (d1), "=&S" (d2)
 243                 : "0" (n >> 2), "g" (n & 3), "1" (dest), "2" (src)
 244                 : "memory");
 245
 246         return dest;
 247 }
 248 #else
 249 void *memcpy(void *dest, const void *src, size_t n)
 250 {
 251         long d0, d1, d2;
 252         asm volatile(
 253                 "rep ; movsq\n\t"
 254                 "movq %4,%%rcx\n\t"
 255                 "rep ; movsb\n\t"
 256                 : "=&c" (d0), "=&D" (d1), "=&S" (d2)
 257                 : "0" (n >> 3), "g" (n & 7), "1" (dest), "2" (src)
 258                 : "memory");
 259
 260         return dest;
 261 }
 262 #endif
 263
 264 static void error(char *x)
 265 {
 266         error_putstr("\n\n");
 267         error_putstr(x);
 268         error_putstr("\n\n -- System halted");
 269
 270         while (1)
 271                 asm("hlt");
 272 }
 273
 274 #if CONFIG_X86_NEED_RELOCS
 275 static void handle_relocations(void *output, unsigned long output_len)
 276 {
 277         int *reloc;
 278         unsigned long delta, map, ptr;
 279         unsigned long min_addr = (unsigned long)output;
 280         unsigned long max_addr = min_addr + output_len;
 281
 282         /*
 283          * Calculate the delta between where vmlinux was linked to load
 284          * and where it was actually loaded.
 285          */
 286         delta = min_addr - LOAD_PHYSICAL_ADDR;
 287         if (!delta) {
 288                 debug_putstr("No relocation needed... ");
 289                 return;
 290         }
 291         debug_putstr("Performing relocations... ");
 292
 293         /*
 294          * The kernel contains a table of relocation addresses. Those
 295          * addresses have the final load address of the kernel in virtual
 296          * memory. We are currently working in the self map. So we need to
 297          * create an adjustment for kernel memory addresses to the self map.
 298          * This will involve subtracting out the base address of the kernel.
 299          */
 300         map = delta - __START_KERNEL_map;
 301
 302         /*
 303          * Process relocations: 32 bit relocations first then 64 bit after.
 304          * Two sets of binary relocations are added to the end of the kernel
 305          * before compression. Each relocation table entry is the kernel
 306          * address of the location which needs to be updated stored as a
 307          * 32-bit value which is sign extended to 64 bits.
 308          *
 309          * Format is:
 310          *
 311          * kernel bits...
 312          * 0 - zero terminator for 64 bit relocations
 313          * 64 bit relocation repeated
 314          * 0 - zero terminator for 32 bit relocations
 315          * 32 bit relocation repeated
 316          *
 317          * So we work backwards from the end of the decompressed image.
 318          */
 319         for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) {
 320                 int extended = *reloc;
 321                 extended += map;
 322
 323                 ptr = (unsigned long)extended;
 324                 if (ptr < min_addr || ptr > max_addr)
 325                         error("32-bit relocation outside of kernel!\n");
 326
 327                 *(uint32_t *)ptr += delta;
 328         }
 329 #ifdef CONFIG_X86_64
 330         for (reloc--; *reloc; reloc--) {
 331                 long extended = *reloc;
 332                 extended += map;
 333
 334                 ptr = (unsigned long)extended;
 335                 if (ptr < min_addr || ptr > max_addr)
 336                         error("64-bit relocation outside of kernel!\n");
 337
 338                 *(uint64_t *)ptr += delta;
 339         }
 340 #endif
 341 }
 342 #else
 343 static inline void handle_relocations(void *output, unsigned long output_len)
 344 { }
 345 #endif
 346
 347 static void parse_elf(void *output)
 348 {
 349 #ifdef CONFIG_X86_64
 350         Elf64_Ehdr ehdr;
 351         Elf64_Phdr *phdrs, *phdr;
 352 #else
 353         Elf32_Ehdr ehdr;
 354         Elf32_Phdr *phdrs, *phdr;
 355 #endif
 356         void *dest;
 357         int i;
 358
 359         memcpy(&ehdr, output, sizeof(ehdr));
 360         if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
 361            ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
 362            ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
 363            ehdr.e_ident[EI_MAG3] != ELFMAG3) {
 364                 error("Kernel is not a valid ELF file");
 365                 return;
 366         }
 367
 368         debug_putstr("Parsing ELF... ");
 369
 370         phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
 371         if (!phdrs)
 372                 error("Failed to allocate space for phdrs");
 373
 374         memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
 375
 376         for (i = 0; i < ehdr.e_phnum; i++) {
 377                 phdr = &phdrs[i];
 378
 379                 switch (phdr->p_type) {
 380                 case PT_LOAD:
 381 #ifdef CONFIG_RELOCATABLE
 382                         dest = output;
 383                         dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
 384 #else
 385                         dest = (void *)(phdr->p_paddr);
 386 #endif
 387                         memcpy(dest,
 388                                output + phdr->p_offset,
 389                                phdr->p_filesz);
 390                         break;
 391                 default: /* Ignore other PT_* */ break;
 392                 }
 393         }
 394
 395         free(phdrs);
 396 }
 397
 398 asmlinkage void decompress_kernel(void *rmode, memptr heap,
 399                                   unsigned char *input_data,
 400                                   unsigned long input_len,
 401                                   unsigned char *output,
 402                                   unsigned long output_len)
 403 {
 404         real_mode = rmode;
 405
 406         sanitize_boot_params(real_mode);
 407
 408         if (real_mode->screen_info.orig_video_mode == 7) {
 409                 vidmem = (char *) 0xb0000;
 410                 vidport = 0x3b4;
 411         } else {
 412                 vidmem = (char *) 0xb8000;
 413                 vidport = 0x3d4;
 414         }
 415
 416         lines = real_mode->screen_info.orig_video_lines;
 417         cols = real_mode->screen_info.orig_video_cols;
 418
 419         console_init();
 420         debug_putstr("early console in decompress_kernel\n");
 421
 422         free_mem_ptr     = heap;        /* Heap */
 423         free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
 424
 425         if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
 426                 error("Destination address inappropriately aligned");
 427 #ifdef CONFIG_X86_64
 428         if (heap > 0x3fffffffffffUL)
 429                 error("Destination address too large");
 430 #else
 431         if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
 432                 error("Destination address too large");
 433 #endif
 434 #ifndef CONFIG_RELOCATABLE
 435         if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
 436                 error("Wrong destination address");
 437 #endif
 438
 439         debug_putstr("\nDecompressing Linux... ");
 440         decompress(input_data, input_len, NULL, NULL, output, NULL, error);
 441         parse_elf(output);
 442         handle_relocations(output, output_len);
 443         debug_putstr("done.\nBooting the kernel.\n");
 444         return;
 445 }