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 #include "../string.h"
  14
  15 /* WARNING!!
  16  * This code is compiled with -fPIC and it is relocated dynamically
  17  * at run time, but no relocation processing is performed.
  18  * This means that it is not safe to place pointers in static structures.
  19  */
  20
  21 /*
  22  * Getting to provable safe in place decompression is hard.
  23  * Worst case behaviours need to be analyzed.
  24  * Background information:
  25  *
  26  * The file layout is:
  27  *    magic[2]
  28  *    method[1]
  29  *    flags[1]
  30  *    timestamp[4]
  31  *    extraflags[1]
  32  *    os[1]
  33  *    compressed data blocks[N]
  34  *    crc[4] orig_len[4]
  35  *
  36  * resulting in 18 bytes of non compressed data overhead.
  37  *
  38  * Files divided into blocks
  39  * 1 bit (last block flag)
  40  * 2 bits (block type)
  41  *
  42  * 1 block occurs every 32K -1 bytes or when there 50% compression
  43  * has been achieved. The smallest block type encoding is always used.
  44  *
  45  * stored:
  46  *    32 bits length in bytes.
  47  *
  48  * fixed:
  49  *    magic fixed tree.
  50  *    symbols.
  51  *
  52  * dynamic:
  53  *    dynamic tree encoding.
  54  *    symbols.
  55  *
  56  *
  57  * The buffer for decompression in place is the length of the
  58  * uncompressed data, plus a small amount extra to keep the algorithm safe.
  59  * The compressed data is placed at the end of the buffer.  The output
  60  * pointer is placed at the start of the buffer and the input pointer
  61  * is placed where the compressed data starts.  Problems will occur
  62  * when the output pointer overruns the input pointer.
  63  *
  64  * The output pointer can only overrun the input pointer if the input
  65  * pointer is moving faster than the output pointer.  A condition only
  66  * triggered by data whose compressed form is larger than the uncompressed
  67  * form.
  68  *
  69  * The worst case at the block level is a growth of the compressed data
  70  * of 5 bytes per 32767 bytes.
  71  *
  72  * The worst case internal to a compressed block is very hard to figure.
  73  * The worst case can at least be boundined by having one bit that represents
  74  * 32764 bytes and then all of the rest of the bytes representing the very
  75  * very last byte.
  76  *
  77  * All of which is enough to compute an amount of extra data that is required
  78  * to be safe.  To avoid problems at the block level allocating 5 extra bytes
  79  * per 32767 bytes of data is sufficient.  To avoind problems internal to a
  80  * block adding an extra 32767 bytes (the worst case uncompressed block size)
  81  * is sufficient, to ensure that in the worst case the decompressed data for
  82  * block will stop the byte before the compressed data for a block begins.
  83  * To avoid problems with the compressed data's meta information an extra 18
  84  * bytes are needed.  Leading to the formula:
  85  *
  86  * extra_bytes = (uncompressed_size >> 12) + 32768 + 18 + decompressor_size.
  87  *
  88  * Adding 8 bytes per 32K is a bit excessive but much easier to calculate.
  89  * Adding 32768 instead of 32767 just makes for round numbers.
  90  * Adding the decompressor_size is necessary as it musht live after all
  91  * of the data as well.  Last I measured the decompressor is about 14K.
  92  * 10K of actual data and 4K of bss.
  93  *
  94  */
  95
  96 /*
  97  * gzip declarations
  98  */
  99 #define STATIC          static
 100
 101 #undef memcpy
 102
 103 /*
 104  * Use a normal definition of memset() from string.c. There are already
 105  * included header files which expect a definition of memset() and by
 106  * the time we define memset macro, it is too late.
 107  */
 108 #undef memset
 109 #define memzero(s, n)   memset((s), 0, (n))
 110
 111
 112 static void error(char *m);
 113
 114 /*
 115  * This is set up by the setup-routine at boot-time
 116  */
 117 struct boot_params *real_mode;          /* Pointer to real-mode data */
 118
 119 memptr free_mem_ptr;
 120 memptr free_mem_end_ptr;
 121
 122 static char *vidmem;
 123 static int vidport;
 124 static int lines, cols;
 125
 126 #ifdef CONFIG_KERNEL_GZIP
 127 #include "../../../../lib/decompress_inflate.c"
 128 #endif
 129
 130 #ifdef CONFIG_KERNEL_BZIP2
 131 #include "../../../../lib/decompress_bunzip2.c"
 132 #endif
 133
 134 #ifdef CONFIG_KERNEL_LZMA
 135 #include "../../../../lib/decompress_unlzma.c"
 136 #endif
 137
 138 #ifdef CONFIG_KERNEL_XZ
 139 #include "../../../../lib/decompress_unxz.c"
 140 #endif
 141
 142 #ifdef CONFIG_KERNEL_LZO
 143 #include "../../../../lib/decompress_unlzo.c"
 144 #endif
 145
 146 #ifdef CONFIG_KERNEL_LZ4
 147 #include "../../../../lib/decompress_unlz4.c"
 148 #endif
 149
 150 static void scroll(void)
 151 {
 152         int i;
 153
 154         memcpy(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
 155         for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
 156                 vidmem[i] = ' ';
 157 }
 158
 159 #define XMTRDY          0x20
 160
 161 #define TXR             0       /*  Transmit register (WRITE) */
 162 #define LSR             5       /*  Line Status               */
 163 static void serial_putchar(int ch)
 164 {
 165         unsigned timeout = 0xffff;
 166
 167         while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
 168                 cpu_relax();
 169
 170         outb(ch, early_serial_base + TXR);
 171 }
 172
 173 void __putstr(const char *s)
 174 {
 175         int x, y, pos;
 176         char c;
 177
 178         if (early_serial_base) {
 179                 const char *str = s;
 180                 while (*str) {
 181                         if (*str == '\n')
 182                                 serial_putchar('\r');
 183                         serial_putchar(*str++);
 184                 }
 185         }
 186
 187         if (real_mode->screen_info.orig_video_mode == 0 &&
 188             lines == 0 && cols == 0)
 189                 return;
 190
 191         x = real_mode->screen_info.orig_x;
 192         y = real_mode->screen_info.orig_y;
 193
 194         while ((c = *s++) != '\0') {
 195                 if (c == '\n') {
 196                         x = 0;
 197                         if (++y >= lines) {
 198                                 scroll();
 199                                 y--;
 200                         }
 201                 } else {
 202                         vidmem[(x + cols * y) * 2] = c;
 203                         if (++x >= cols) {
 204                                 x = 0;
 205                                 if (++y >= lines) {
 206                                         scroll();
 207                                         y--;
 208                                 }
 209                         }
 210                 }
 211         }
 212
 213         real_mode->screen_info.orig_x = x;
 214         real_mode->screen_info.orig_y = y;
 215
 216         pos = (x + cols * y) * 2;       /* Update cursor position */
 217         outb(14, vidport);
 218         outb(0xff & (pos >> 9), vidport+1);
 219         outb(15, vidport);
 220         outb(0xff & (pos >> 1), vidport+1);
 221 }
 222
 223 void __puthex(unsigned long value)
 224 {
 225         char alpha[2] = "0";
 226         int bits;
 227
 228         for (bits = sizeof(value) * 8 - 4; bits >= 0; bits -= 4) {
 229                 unsigned long digit = (value >> bits) & 0xf;
 230
 231                 if (digit < 0xA)
 232                         alpha[0] = '0' + digit;
 233                 else
 234                         alpha[0] = 'a' + (digit - 0xA);
 235
 236                 __putstr(alpha);
 237         }
 238 }
 239
 240 static void error(char *x)
 241 {
 242         error_putstr("\n\n");
 243         error_putstr(x);
 244         error_putstr("\n\n -- System halted");
 245
 246         while (1)
 247                 asm("hlt");
 248 }
 249
 250 #if CONFIG_X86_NEED_RELOCS
 251 static void handle_relocations(void *output, unsigned long output_len)
 252 {
 253         int *reloc;
 254         unsigned long delta, map, ptr;
 255         unsigned long min_addr = (unsigned long)output;
 256         unsigned long max_addr = min_addr + output_len;
 257
 258         /*
 259          * Calculate the delta between where vmlinux was linked to load
 260          * and where it was actually loaded.
 261          */
 262         delta = min_addr - LOAD_PHYSICAL_ADDR;
 263         if (!delta) {
 264                 debug_putstr("No relocation needed... ");
 265                 return;
 266         }
 267         debug_putstr("Performing relocations... ");
 268
 269         /*
 270          * The kernel contains a table of relocation addresses. Those
 271          * addresses have the final load address of the kernel in virtual
 272          * memory. We are currently working in the self map. So we need to
 273          * create an adjustment for kernel memory addresses to the self map.
 274          * This will involve subtracting out the base address of the kernel.
 275          */
 276         map = delta - __START_KERNEL_map;
 277
 278         /*
 279          * Process relocations: 32 bit relocations first then 64 bit after.
 280          * Three sets of binary relocations are added to the end of the kernel
 281          * before compression. Each relocation table entry is the kernel
 282          * address of the location which needs to be updated stored as a
 283          * 32-bit value which is sign extended to 64 bits.
 284          *
 285          * Format is:
 286          *
 287          * kernel bits...
 288          * 0 - zero terminator for 64 bit relocations
 289          * 64 bit relocation repeated
 290          * 0 - zero terminator for inverse 32 bit relocations
 291          * 32 bit inverse relocation repeated
 292          * 0 - zero terminator for 32 bit relocations
 293          * 32 bit relocation repeated
 294          *
 295          * So we work backwards from the end of the decompressed image.
 296          */
 297         for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) {
 298                 int extended = *reloc;
 299                 extended += map;
 300
 301                 ptr = (unsigned long)extended;
 302                 if (ptr < min_addr || ptr > max_addr)
 303                         error("32-bit relocation outside of kernel!\n");
 304
 305                 *(uint32_t *)ptr += delta;
 306         }
 307 #ifdef CONFIG_X86_64
 308         while (*--reloc) {
 309                 long extended = *reloc;
 310                 extended += map;
 311
 312                 ptr = (unsigned long)extended;
 313                 if (ptr < min_addr || ptr > max_addr)
 314                         error("inverse 32-bit relocation outside of kernel!\n");
 315
 316                 *(int32_t *)ptr -= delta;
 317         }
 318         for (reloc--; *reloc; reloc--) {
 319                 long extended = *reloc;
 320                 extended += map;
 321
 322                 ptr = (unsigned long)extended;
 323                 if (ptr < min_addr || ptr > max_addr)
 324                         error("64-bit relocation outside of kernel!\n");
 325
 326                 *(uint64_t *)ptr += delta;
 327         }
 328 #endif
 329 }
 330 #else
 331 static inline void handle_relocations(void *output, unsigned long output_len)
 332 { }
 333 #endif
 334
 335 static void parse_elf(void *output)
 336 {
 337 #ifdef CONFIG_X86_64
 338         Elf64_Ehdr ehdr;
 339         Elf64_Phdr *phdrs, *phdr;
 340 #else
 341         Elf32_Ehdr ehdr;
 342         Elf32_Phdr *phdrs, *phdr;
 343 #endif
 344         void *dest;
 345         int i;
 346
 347         memcpy(&ehdr, output, sizeof(ehdr));
 348         if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
 349            ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
 350            ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
 351            ehdr.e_ident[EI_MAG3] != ELFMAG3) {
 352                 error("Kernel is not a valid ELF file");
 353                 return;
 354         }
 355
 356         debug_putstr("Parsing ELF... ");
 357
 358         phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
 359         if (!phdrs)
 360                 error("Failed to allocate space for phdrs");
 361
 362         memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
 363
 364         for (i = 0; i < ehdr.e_phnum; i++) {
 365                 phdr = &phdrs[i];
 366
 367                 switch (phdr->p_type) {
 368                 case PT_LOAD:
 369 #ifdef CONFIG_RELOCATABLE
 370                         dest = output;
 371                         dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
 372 #else
 373                         dest = (void *)(phdr->p_paddr);
 374 #endif
 375                         memcpy(dest,
 376                                output + phdr->p_offset,
 377                                phdr->p_filesz);
 378                         break;
 379                 default: /* Ignore other PT_* */ break;
 380                 }
 381         }
 382
 383         free(phdrs);
 384 }
 385
 386 asmlinkage __visible void *decompress_kernel(void *rmode, memptr heap,
 387                                   unsigned char *input_data,
 388                                   unsigned long input_len,
 389                                   unsigned char *output,
 390                                   unsigned long output_len,
 391                                   unsigned long run_size)
 392 {
 393         unsigned char *output_orig = output;
 394
 395         real_mode = rmode;
 396
 397         /* Clear it for solely in-kernel use */
 398         real_mode->hdr.loadflags &= ~KASLR_FLAG;
 399
 400         sanitize_boot_params(real_mode);
 401
 402         if (real_mode->screen_info.orig_video_mode == 7) {
 403                 vidmem = (char *) 0xb0000;
 404                 vidport = 0x3b4;
 405         } else {
 406                 vidmem = (char *) 0xb8000;
 407                 vidport = 0x3d4;
 408         }
 409
 410         lines = real_mode->screen_info.orig_video_lines;
 411         cols = real_mode->screen_info.orig_video_cols;
 412
 413         console_init();
 414         debug_putstr("early console in decompress_kernel\n");
 415
 416         free_mem_ptr     = heap;        /* Heap */
 417         free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
 418
 419         /* Report initial kernel position details. */
 420         debug_putaddr(input_data);
 421         debug_putaddr(input_len);
 422         debug_putaddr(output);
 423         debug_putaddr(output_len);
 424         debug_putaddr(run_size);
 425
 426         /*
 427          * The memory hole needed for the kernel is the larger of either
 428          * the entire decompressed kernel plus relocation table, or the
 429          * entire decompressed kernel plus .bss and .brk sections.
 430          */
 431         output = choose_kernel_location(real_mode, input_data, input_len, output,
 432                                         output_len > run_size ? output_len
 433                                                               : run_size);
 434
 435         /* Validate memory location choices. */
 436         if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
 437                 error("Destination address inappropriately aligned");
 438 #ifdef CONFIG_X86_64
 439         if (heap > 0x3fffffffffffUL)
 440                 error("Destination address too large");
 441 #else
 442         if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
 443                 error("Destination address too large");
 444 #endif
 445 #ifndef CONFIG_RELOCATABLE
 446         if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
 447                 error("Wrong destination address");
 448 #endif
 449
 450         debug_putstr("\nDecompressing Linux... ");
 451         __decompress(input_data, input_len, NULL, NULL, output, output_len,
 452                         NULL, error);
 453         parse_elf(output);
 454         /*
 455          * 32-bit always performs relocations. 64-bit relocations are only
 456          * needed if kASLR has chosen a different load address.
 457          */
 458         if (!IS_ENABLED(CONFIG_X86_64) || output != output_orig)
 459                 handle_relocations(output, output_len);
 460         debug_putstr("done.\nBooting the kernel.\n");
 461         return output;
 462 }