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 static void scroll(void)
 149 {
 150         int i;
 151
 152         memcpy(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
 153         for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
 154                 vidmem[i] = ' ';
 155 }
 156
 157 #define XMTRDY          0x20
 158
 159 #define TXR             0       /*  Transmit register (WRITE) */
 160 #define LSR             5       /*  Line Status               */
 161 static void serial_putchar(int ch)
 162 {
 163         unsigned timeout = 0xffff;
 164
 165         while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
 166                 cpu_relax();
 167
 168         outb(ch, early_serial_base + TXR);
 169 }
 170
 171 void __putstr(const char *s)
 172 {
 173         int x, y, pos;
 174         char c;
 175
 176         if (early_serial_base) {
 177                 const char *str = s;
 178                 while (*str) {
 179                         if (*str == '\n')
 180                                 serial_putchar('\r');
 181                         serial_putchar(*str++);
 182                 }
 183         }
 184
 185         if (real_mode->screen_info.orig_video_mode == 0 &&
 186             lines == 0 && cols == 0)
 187                 return;
 188
 189         x = real_mode->screen_info.orig_x;
 190         y = real_mode->screen_info.orig_y;
 191
 192         while ((c = *s++) != '\0') {
 193                 if (c == '\n') {
 194                         x = 0;
 195                         if (++y >= lines) {
 196                                 scroll();
 197                                 y--;
 198                         }
 199                 } else {
 200                         vidmem[(x + cols * y) * 2] = c;
 201                         if (++x >= cols) {
 202                                 x = 0;
 203                                 if (++y >= lines) {
 204                                         scroll();
 205                                         y--;
 206                                 }
 207                         }
 208                 }
 209         }
 210
 211         real_mode->screen_info.orig_x = x;
 212         real_mode->screen_info.orig_y = y;
 213
 214         pos = (x + cols * y) * 2;       /* Update cursor position */
 215         outb(14, vidport);
 216         outb(0xff & (pos >> 9), vidport+1);
 217         outb(15, vidport);
 218         outb(0xff & (pos >> 1), vidport+1);
 219 }
 220
 221 void *memset(void *s, int c, size_t n)
 222 {
 223         int i;
 224         char *ss = s;
 225
 226         for (i = 0; i < n; i++)
 227                 ss[i] = c;
 228         return s;
 229 }
 230 #ifdef CONFIG_X86_32
 231 void *memcpy(void *dest, const void *src, size_t n)
 232 {
 233         int d0, d1, d2;
 234         asm volatile(
 235                 "rep ; movsl\n\t"
 236                 "movl %4,%%ecx\n\t"
 237                 "rep ; movsb\n\t"
 238                 : "=&c" (d0), "=&D" (d1), "=&S" (d2)
 239                 : "0" (n >> 2), "g" (n & 3), "1" (dest), "2" (src)
 240                 : "memory");
 241
 242         return dest;
 243 }
 244 #else
 245 void *memcpy(void *dest, const void *src, size_t n)
 246 {
 247         long d0, d1, d2;
 248         asm volatile(
 249                 "rep ; movsq\n\t"
 250                 "movq %4,%%rcx\n\t"
 251                 "rep ; movsb\n\t"
 252                 : "=&c" (d0), "=&D" (d1), "=&S" (d2)
 253                 : "0" (n >> 3), "g" (n & 7), "1" (dest), "2" (src)
 254                 : "memory");
 255
 256         return dest;
 257 }
 258 #endif
 259
 260 static void error(char *x)
 261 {
 262         error_putstr("\n\n");
 263         error_putstr(x);
 264         error_putstr("\n\n -- System halted");
 265
 266         while (1)
 267                 asm("hlt");
 268 }
 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_RELOCATABLE
 305                         dest = output;
 306                         dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
 307 #else
 308                         dest = (void *)(phdr->p_paddr);
 309 #endif
 310                         memcpy(dest,
 311                                output + phdr->p_offset,
 312                                phdr->p_filesz);
 313                         break;
 314                 default: /* Ignore other PT_* */ break;
 315                 }
 316         }
 317
 318         free(phdrs);
 319 }
 320
 321 asmlinkage void decompress_kernel(void *rmode, memptr heap,
 322                                   unsigned char *input_data,
 323                                   unsigned long input_len,
 324                                   unsigned char *output)
 325 {
 326         real_mode = rmode;
 327
 328         sanitize_boot_params(real_mode);
 329
 330         if (real_mode->screen_info.orig_video_mode == 7) {
 331                 vidmem = (char *) 0xb0000;
 332                 vidport = 0x3b4;
 333         } else {
 334                 vidmem = (char *) 0xb8000;
 335                 vidport = 0x3d4;
 336         }
 337
 338         lines = real_mode->screen_info.orig_video_lines;
 339         cols = real_mode->screen_info.orig_video_cols;
 340
 341         console_init();
 342         debug_putstr("early console in decompress_kernel\n");
 343
 344         free_mem_ptr     = heap;        /* Heap */
 345         free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
 346
 347         if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
 348                 error("Destination address inappropriately aligned");
 349 #ifdef CONFIG_X86_64
 350         if (heap > 0x3fffffffffffUL)
 351                 error("Destination address too large");
 352 #else
 353         if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
 354                 error("Destination address too large");
 355 #endif
 356 #ifndef CONFIG_RELOCATABLE
 357         if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
 358                 error("Wrong destination address");
 359 #endif
 360
 361         debug_putstr("\nDecompressing Linux... ");
 362         decompress(input_data, input_len, NULL, NULL, output, NULL, error);
 363         parse_elf(output);
 364         debug_putstr("done.\nBooting the kernel.\n");
 365         return;
 366 }