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 /*
  13  * we have to be careful, because no indirections are allowed here, and
  14  * paravirt_ops is a kind of one. As it will only run in baremetal anyway,
  15  * we just keep it from happening
  16  */
  17 #undef CONFIG_PARAVIRT
  18 #ifdef CONFIG_X86_32
  19 #define ASM_X86__DESC_H 1
  20 #endif
  21
  22 #ifdef CONFIG_X86_64
  23 #define _LINUX_STRING_H_ 1
  24 #define __LINUX_BITMAP_H 1
  25 #endif
  26
  27 #include <linux/linkage.h>
  28 #include <linux/screen_info.h>
  29 #include <linux/elf.h>
  30 #include <asm/io.h>
  31 #include <asm/page.h>
  32 #include <asm/boot.h>
  33 #include <asm/bootparam.h>
  34
  35 /* WARNING!!
  36  * This code is compiled with -fPIC and it is relocated dynamically
  37  * at run time, but no relocation processing is performed.
  38  * This means that it is not safe to place pointers in static structures.
  39  */
  40
  41 /*
  42  * Getting to provable safe in place decompression is hard.
  43  * Worst case behaviours need to be analyzed.
  44  * Background information:
  45  *
  46  * The file layout is:
  47  *    magic[2]
  48  *    method[1]
  49  *    flags[1]
  50  *    timestamp[4]
  51  *    extraflags[1]
  52  *    os[1]
  53  *    compressed data blocks[N]
  54  *    crc[4] orig_len[4]
  55  *
  56  * resulting in 18 bytes of non compressed data overhead.
  57  *
  58  * Files divided into blocks
  59  * 1 bit (last block flag)
  60  * 2 bits (block type)
  61  *
  62  * 1 block occurs every 32K -1 bytes or when there 50% compression
  63  * has been achieved. The smallest block type encoding is always used.
  64  *
  65  * stored:
  66  *    32 bits length in bytes.
  67  *
  68  * fixed:
  69  *    magic fixed tree.
  70  *    symbols.
  71  *
  72  * dynamic:
  73  *    dynamic tree encoding.
  74  *    symbols.
  75  *
  76  *
  77  * The buffer for decompression in place is the length of the
  78  * uncompressed data, plus a small amount extra to keep the algorithm safe.
  79  * The compressed data is placed at the end of the buffer.  The output
  80  * pointer is placed at the start of the buffer and the input pointer
  81  * is placed where the compressed data starts.  Problems will occur
  82  * when the output pointer overruns the input pointer.
  83  *
  84  * The output pointer can only overrun the input pointer if the input
  85  * pointer is moving faster than the output pointer.  A condition only
  86  * triggered by data whose compressed form is larger than the uncompressed
  87  * form.
  88  *
  89  * The worst case at the block level is a growth of the compressed data
  90  * of 5 bytes per 32767 bytes.
  91  *
  92  * The worst case internal to a compressed block is very hard to figure.
  93  * The worst case can at least be boundined by having one bit that represents
  94  * 32764 bytes and then all of the rest of the bytes representing the very
  95  * very last byte.
  96  *
  97  * All of which is enough to compute an amount of extra data that is required
  98  * to be safe.  To avoid problems at the block level allocating 5 extra bytes
  99  * per 32767 bytes of data is sufficient.  To avoind problems internal to a
 100  * block adding an extra 32767 bytes (the worst case uncompressed block size)
 101  * is sufficient, to ensure that in the worst case the decompressed data for
 102  * block will stop the byte before the compressed data for a block begins.
 103  * To avoid problems with the compressed data's meta information an extra 18
 104  * bytes are needed.  Leading to the formula:
 105  *
 106  * extra_bytes = (uncompressed_size >> 12) + 32768 + 18 + decompressor_size.
 107  *
 108  * Adding 8 bytes per 32K is a bit excessive but much easier to calculate.
 109  * Adding 32768 instead of 32767 just makes for round numbers.
 110  * Adding the decompressor_size is necessary as it musht live after all
 111  * of the data as well.  Last I measured the decompressor is about 14K.
 112  * 10K of actual data and 4K of bss.
 113  *
 114  */
 115
 116 /*
 117  * gzip declarations
 118  */
 119
 120 #define OF(args)        args
 121 #define STATIC          static
 122
 123 #undef memset
 124 #undef memcpy
 125 #define memzero(s, n)   memset((s), 0, (n))
 126
 127 typedef unsigned char   uch;
 128 typedef unsigned short  ush;
 129 typedef unsigned long   ulg;
 130
 131 /*
 132  * Window size must be at least 32k, and a power of two.
 133  * We don't actually have a window just a huge output buffer,
 134  * so we report a 2G window size, as that should always be
 135  * larger than our output buffer:
 136  */
 137 #define WSIZE           0x80000000
 138
 139 /* Input buffer: */
 140 static unsigned char    *inbuf;
 141
 142 /* Sliding window buffer (and final output buffer): */
 143 static unsigned char    *window;
 144
 145 /* Valid bytes in inbuf: */
 146 static unsigned         insize;
 147
 148 /* Index of next byte to be processed in inbuf: */
 149 static unsigned         inptr;
 150
 151 /* Bytes in output buffer: */
 152 static unsigned         outcnt;
 153
 154 /* gzip flag byte */
 155 #define ASCII_FLAG      0x01 /* bit 0 set: file probably ASCII text */
 156 #define CONTINUATION    0x02 /* bit 1 set: continuation of multi-part gz file */
 157 #define EXTRA_FIELD     0x04 /* bit 2 set: extra field present */
 158 #define ORIG_NAM        0x08 /* bit 3 set: original file name present */
 159 #define COMMENT         0x10 /* bit 4 set: file comment present */
 160 #define ENCRYPTED       0x20 /* bit 5 set: file is encrypted */
 161 #define RESERVED        0xC0 /* bit 6, 7:  reserved */
 162
 163 #define get_byte()      (inptr < insize ? inbuf[inptr++] : fill_inbuf())
 164
 165 /* Diagnostic functions */
 166 #ifdef DEBUG
 167 #  define Assert(cond, msg) do { if (!(cond)) error(msg); } while (0)
 168 #  define Trace(x)      do { fprintf x; } while (0)
 169 #  define Tracev(x)     do { if (verbose) fprintf x ; } while (0)
 170 #  define Tracevv(x)    do { if (verbose > 1) fprintf x ; } while (0)
 171 #  define Tracec(c, x)  do { if (verbose && (c)) fprintf x ; } while (0)
 172 #  define Tracecv(c, x) do { if (verbose > 1 && (c)) fprintf x ; } while (0)
 173 #else
 174 #  define Assert(cond, msg)
 175 #  define Trace(x)
 176 #  define Tracev(x)
 177 #  define Tracevv(x)
 178 #  define Tracec(c, x)
 179 #  define Tracecv(c, x)
 180 #endif
 181
 182 static int  fill_inbuf(void);
 183 static void flush_window(void);
 184 static void error(char *m);
 185
 186 /*
 187  * This is set up by the setup-routine at boot-time
 188  */
 189 static struct boot_params *real_mode;           /* Pointer to real-mode data */
 190 static int quiet;
 191
 192 extern unsigned char input_data[];
 193 extern int input_len;
 194
 195 static long bytes_out;
 196
 197 static void *memset(void *s, int c, unsigned n);
 198 static void *memcpy(void *dest, const void *src, unsigned n);
 199
 200 static void __putstr(int, const char *);
 201 #define putstr(__x)  __putstr(0, __x)
 202
 203 #ifdef CONFIG_X86_64
 204 #define memptr long
 205 #else
 206 #define memptr unsigned
 207 #endif
 208
 209 static memptr free_mem_ptr;
 210 static memptr free_mem_end_ptr;
 211
 212 static char *vidmem;
 213 static int vidport;
 214 static int lines, cols;
 215
 216 #include "../../../../lib/inflate.c"
 217
 218 static void scroll(void)
 219 {
 220         int i;
 221
 222         memcpy(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
 223         for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
 224                 vidmem[i] = ' ';
 225 }
 226
 227 static void __putstr(int error, const char *s)
 228 {
 229         int x, y, pos;
 230         char c;
 231
 232 #ifndef CONFIG_X86_VERBOSE_BOOTUP
 233         if (!error)
 234                 return;
 235 #endif
 236
 237 #ifdef CONFIG_X86_32
 238         if (real_mode->screen_info.orig_video_mode == 0 &&
 239             lines == 0 && cols == 0)
 240                 return;
 241 #endif
 242
 243         x = real_mode->screen_info.orig_x;
 244         y = real_mode->screen_info.orig_y;
 245
 246         while ((c = *s++) != '\0') {
 247                 if (c == '\n') {
 248                         x = 0;
 249                         if (++y >= lines) {
 250                                 scroll();
 251                                 y--;
 252                         }
 253                 } else {
 254                         vidmem [(x + cols * y) * 2] = c;
 255                         if (++x >= cols) {
 256                                 x = 0;
 257                                 if (++y >= lines) {
 258                                         scroll();
 259                                         y--;
 260                                 }
 261                         }
 262                 }
 263         }
 264
 265         real_mode->screen_info.orig_x = x;
 266         real_mode->screen_info.orig_y = y;
 267
 268         pos = (x + cols * y) * 2;       /* Update cursor position */
 269         outb(14, vidport);
 270         outb(0xff & (pos >> 9), vidport+1);
 271         outb(15, vidport);
 272         outb(0xff & (pos >> 1), vidport+1);
 273 }
 274
 275 static void *memset(void *s, int c, unsigned n)
 276 {
 277         int i;
 278         char *ss = s;
 279
 280         for (i = 0; i < n; i++) ss[i] = c;
 281         return s;
 282 }
 283
 284 static void *memcpy(void *dest, const void *src, unsigned n)
 285 {
 286         int i;
 287         const char *s = src;
 288         char *d = dest;
 289
 290         for (i = 0; i < n; i++) d[i] = s[i];
 291         return dest;
 292 }
 293
 294 /* ===========================================================================
 295  * Fill the input buffer. This is called only when the buffer is empty
 296  * and at least one byte is really needed.
 297  */
 298 static int fill_inbuf(void)
 299 {
 300         error("ran out of input data");
 301         return 0;
 302 }
 303
 304 /* ===========================================================================
 305  * Write the output window window[0..outcnt-1] and update crc and bytes_out.
 306  * (Used for the decompressed data only.)
 307  */
 308 static void flush_window(void)
 309 {
 310         /* With my window equal to my output buffer
 311          * I only need to compute the crc here.
 312          */
 313         unsigned long c = crc;         /* temporary variable */
 314         unsigned n;
 315         unsigned char *in, ch;
 316
 317         in = window;
 318         for (n = 0; n < outcnt; n++) {
 319                 ch = *in++;
 320                 c = crc_32_tab[((int)c ^ ch) & 0xff] ^ (c >> 8);
 321         }
 322         crc = c;
 323         bytes_out += (unsigned long)outcnt;
 324         outcnt = 0;
 325 }
 326
 327 static void error(char *x)
 328 {
 329         __putstr(1, "\n\n");
 330         __putstr(1, x);
 331         __putstr(1, "\n\n -- System halted");
 332
 333         while (1)
 334                 asm("hlt");
 335 }
 336
 337 static void parse_elf(void *output)
 338 {
 339 #ifdef CONFIG_X86_64
 340         Elf64_Ehdr ehdr;
 341         Elf64_Phdr *phdrs, *phdr;
 342 #else
 343         Elf32_Ehdr ehdr;
 344         Elf32_Phdr *phdrs, *phdr;
 345 #endif
 346         void *dest;
 347         int i;
 348
 349         memcpy(&ehdr, output, sizeof(ehdr));
 350         if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
 351            ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
 352            ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
 353            ehdr.e_ident[EI_MAG3] != ELFMAG3) {
 354                 error("Kernel is not a valid ELF file");
 355                 return;
 356         }
 357
 358         if (!quiet)
 359                 putstr("Parsing ELF... ");
 360
 361         phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
 362         if (!phdrs)
 363                 error("Failed to allocate space for phdrs");
 364
 365         memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
 366
 367         for (i = 0; i < ehdr.e_phnum; i++) {
 368                 phdr = &phdrs[i];
 369
 370                 switch (phdr->p_type) {
 371                 case PT_LOAD:
 372 #ifdef CONFIG_RELOCATABLE
 373                         dest = output;
 374                         dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
 375 #else
 376                         dest = (void *)(phdr->p_paddr);
 377 #endif
 378                         memcpy(dest,
 379                                output + phdr->p_offset,
 380                                phdr->p_filesz);
 381                         break;
 382                 default: /* Ignore other PT_* */ break;
 383                 }
 384         }
 385 }
 386
 387 asmlinkage void decompress_kernel(void *rmode, memptr heap,
 388                                   unsigned char *input_data,
 389                                   unsigned long input_len,
 390                                   unsigned char *output)
 391 {
 392         real_mode = rmode;
 393
 394         if (real_mode->hdr.loadflags & QUIET_FLAG)
 395                 quiet = 1;
 396
 397         if (real_mode->screen_info.orig_video_mode == 7) {
 398                 vidmem = (char *) 0xb0000;
 399                 vidport = 0x3b4;
 400         } else {
 401                 vidmem = (char *) 0xb8000;
 402                 vidport = 0x3d4;
 403         }
 404
 405         lines = real_mode->screen_info.orig_video_lines;
 406         cols = real_mode->screen_info.orig_video_cols;
 407
 408         window = output;                /* Output buffer (Normally at 1M) */
 409         free_mem_ptr     = heap;        /* Heap */
 410         free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
 411         inbuf  = input_data;            /* Input buffer */
 412         insize = input_len;
 413         inptr  = 0;
 414
 415 #ifdef CONFIG_X86_64
 416         if ((unsigned long)output & (__KERNEL_ALIGN - 1))
 417                 error("Destination address not 2M aligned");
 418         if ((unsigned long)output >= 0xffffffffffUL)
 419                 error("Destination address too large");
 420 #else
 421         if ((u32)output & (CONFIG_PHYSICAL_ALIGN - 1))
 422                 error("Destination address not CONFIG_PHYSICAL_ALIGN aligned");
 423         if (heap > ((-__PAGE_OFFSET-(512<<20)-1) & 0x7fffffff))
 424                 error("Destination address too large");
 425 #ifndef CONFIG_RELOCATABLE
 426         if ((u32)output != LOAD_PHYSICAL_ADDR)
 427                 error("Wrong destination address");
 428 #endif
 429 #endif
 430
 431         makecrc();
 432         if (!quiet)
 433                 putstr("\nDecompressing Linux... ");
 434         gunzip();
 435         parse_elf(output);
 436         if (!quiet)
 437                 putstr("done.\nBooting the kernel.\n");
 438         return;
 439 }