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 <linux/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 #define STATIC          static
 120
 121 #undef memset
 122 #undef memcpy
 123 #define memzero(s, n)   memset((s), 0, (n))
 124
 125
 126 static void error(char *m);
 127
 128 /*
 129  * This is set up by the setup-routine at boot-time
 130  */
 131 static struct boot_params *real_mode;           /* Pointer to real-mode data */
 132 static int quiet;
 133
 134 static void *memset(void *s, int c, unsigned n);
 135 void *memcpy(void *dest, const void *src, unsigned n);
 136
 137 static void __putstr(int, const char *);
 138 #define putstr(__x)  __putstr(0, __x)
 139
 140 #ifdef CONFIG_X86_64
 141 #define memptr long
 142 #else
 143 #define memptr unsigned
 144 #endif
 145
 146 static memptr free_mem_ptr;
 147 static memptr free_mem_end_ptr;
 148
 149 static char *vidmem;
 150 static int vidport;
 151 static int lines, cols;
 152
 153 #ifdef CONFIG_KERNEL_GZIP
 154 #include "../../../../lib/decompress_inflate.c"
 155 #endif
 156
 157 #ifdef CONFIG_KERNEL_BZIP2
 158 #include "../../../../lib/decompress_bunzip2.c"
 159 #endif
 160
 161 #ifdef CONFIG_KERNEL_LZMA
 162 #include "../../../../lib/decompress_unlzma.c"
 163 #endif
 164
 165 static void scroll(void)
 166 {
 167         int i;
 168
 169         memcpy(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
 170         for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
 171                 vidmem[i] = ' ';
 172 }
 173
 174 static void __putstr(int error, const char *s)
 175 {
 176         int x, y, pos;
 177         char c;
 178
 179 #ifndef CONFIG_X86_VERBOSE_BOOTUP
 180         if (!error)
 181                 return;
 182 #endif
 183
 184 #ifdef CONFIG_X86_32
 185         if (real_mode->screen_info.orig_video_mode == 0 &&
 186             lines == 0 && cols == 0)
 187                 return;
 188 #endif
 189
 190         x = real_mode->screen_info.orig_x;
 191         y = real_mode->screen_info.orig_y;
 192
 193         while ((c = *s++) != '\0') {
 194                 if (c == '\n') {
 195                         x = 0;
 196                         if (++y >= lines) {
 197                                 scroll();
 198                                 y--;
 199                         }
 200                 } else {
 201                         vidmem[(x + cols * y) * 2] = c;
 202                         if (++x >= cols) {
 203                                 x = 0;
 204                                 if (++y >= lines) {
 205                                         scroll();
 206                                         y--;
 207                                 }
 208                         }
 209                 }
 210         }
 211
 212         real_mode->screen_info.orig_x = x;
 213         real_mode->screen_info.orig_y = y;
 214
 215         pos = (x + cols * y) * 2;       /* Update cursor position */
 216         outb(14, vidport);
 217         outb(0xff & (pos >> 9), vidport+1);
 218         outb(15, vidport);
 219         outb(0xff & (pos >> 1), vidport+1);
 220 }
 221
 222 static void *memset(void *s, int c, unsigned n)
 223 {
 224         int i;
 225         char *ss = s;
 226
 227         for (i = 0; i < n; i++)
 228                 ss[i] = c;
 229         return s;
 230 }
 231
 232 void *memcpy(void *dest, const void *src, unsigned n)
 233 {
 234         int i;
 235         const char *s = src;
 236         char *d = dest;
 237
 238         for (i = 0; i < n; i++)
 239                 d[i] = s[i];
 240         return dest;
 241 }
 242
 243
 244 static void error(char *x)
 245 {
 246         __putstr(1, "\n\n");
 247         __putstr(1, x);
 248         __putstr(1, "\n\n -- System halted");
 249
 250         while (1)
 251                 asm("hlt");
 252 }
 253
 254 static void parse_elf(void *output)
 255 {
 256 #ifdef CONFIG_X86_64
 257         Elf64_Ehdr ehdr;
 258         Elf64_Phdr *phdrs, *phdr;
 259 #else
 260         Elf32_Ehdr ehdr;
 261         Elf32_Phdr *phdrs, *phdr;
 262 #endif
 263         void *dest;
 264         int i;
 265
 266         memcpy(&ehdr, output, sizeof(ehdr));
 267         if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
 268            ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
 269            ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
 270            ehdr.e_ident[EI_MAG3] != ELFMAG3) {
 271                 error("Kernel is not a valid ELF file");
 272                 return;
 273         }
 274
 275         if (!quiet)
 276                 putstr("Parsing ELF... ");
 277
 278         phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
 279         if (!phdrs)
 280                 error("Failed to allocate space for phdrs");
 281
 282         memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
 283
 284         for (i = 0; i < ehdr.e_phnum; i++) {
 285                 phdr = &phdrs[i];
 286
 287                 switch (phdr->p_type) {
 288                 case PT_LOAD:
 289 #ifdef CONFIG_RELOCATABLE
 290                         dest = output;
 291                         dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
 292 #else
 293                         dest = (void *)(phdr->p_paddr);
 294 #endif
 295                         memcpy(dest,
 296                                output + phdr->p_offset,
 297                                phdr->p_filesz);
 298                         break;
 299                 default: /* Ignore other PT_* */ break;
 300                 }
 301         }
 302 }
 303
 304 asmlinkage void decompress_kernel(void *rmode, memptr heap,
 305                                   unsigned char *input_data,
 306                                   unsigned long input_len,
 307                                   unsigned char *output)
 308 {
 309         real_mode = rmode;
 310
 311         if (real_mode->hdr.loadflags & QUIET_FLAG)
 312                 quiet = 1;
 313
 314         if (real_mode->screen_info.orig_video_mode == 7) {
 315                 vidmem = (char *) 0xb0000;
 316                 vidport = 0x3b4;
 317         } else {
 318                 vidmem = (char *) 0xb8000;
 319                 vidport = 0x3d4;
 320         }
 321
 322         lines = real_mode->screen_info.orig_video_lines;
 323         cols = real_mode->screen_info.orig_video_cols;
 324
 325         free_mem_ptr     = heap;        /* Heap */
 326         free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
 327
 328         if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
 329                 error("Destination address inappropriately aligned");
 330 #ifdef CONFIG_X86_64
 331         if (heap > 0x3fffffffffffUL)
 332                 error("Destination address too large");
 333 #else
 334         if (heap > ((-__PAGE_OFFSET-(512<<20)-1) & 0x7fffffff))
 335                 error("Destination address too large");
 336 #endif
 337 #ifndef CONFIG_RELOCATABLE
 338         if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
 339                 error("Wrong destination address");
 340 #endif
 341
 342         if (!quiet)
 343                 putstr("\nDecompressing Linux... ");
 344         decompress(input_data, input_len, NULL, NULL, output, NULL, error);
 345         parse_elf(output);
 346         if (!quiet)
 347                 putstr("done.\nBooting the kernel.\n");
 348         return;
 349 }