arch/x86/boot/compressed/misc.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * misc.c
   4  *
   5  * This is a collection of several routines used to extract the kernel
   6  * which includes KASLR relocation, decompression, ELF parsing, and
   7  * relocation processing. Additionally included are the screen and serial
   8  * output functions and related debugging support functions.
   9  *
  10  * malloc by Hannu Savolainen 1993 and Matthias Urlichs 1994
  11  * puts by Nick Holloway 1993, better puts by Martin Mares 1995
  12  * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
  13  */
  14
  15 #include "misc.h"
  16 #include "error.h"
  17 #include "pgtable.h"
  18 #include "../string.h"
  19 #include "../voffset.h"
  20
  21 /*
  22  * WARNING!!
  23  * This code is compiled with -fPIC and it is relocated dynamically at
  24  * run time, but no relocation processing is performed. This means that
  25  * it is not safe to place pointers in static structures.
  26  */
  27
  28 /* Macros used by the included decompressor code below. */
  29 #define STATIC          static
  30
  31 /*
  32  * Use normal definitions of mem*() from string.c. There are already
  33  * included header files which expect a definition of memset() and by
  34  * the time we define memset macro, it is too late.
  35  */
  36 #undef memcpy
  37 #undef memset
  38 #define memzero(s, n)   memset((s), 0, (n))
  39 #define memmove         memmove
  40
  41 /* Functions used by the included decompressor code below. */
  42 void *memmove(void *dest, const void *src, size_t n);
  43
  44 /*
  45  * This is set up by the setup-routine at boot-time
  46  */
  47 struct boot_params *boot_params;
  48
  49 memptr free_mem_ptr;
  50 memptr free_mem_end_ptr;
  51
  52 static char *vidmem;
  53 static int vidport;
  54 static int lines, cols;
  55
  56 #ifdef CONFIG_KERNEL_GZIP
  57 #include "../../../../lib/decompress_inflate.c"
  58 #endif
  59
  60 #ifdef CONFIG_KERNEL_BZIP2
  61 #include "../../../../lib/decompress_bunzip2.c"
  62 #endif
  63
  64 #ifdef CONFIG_KERNEL_LZMA
  65 #include "../../../../lib/decompress_unlzma.c"
  66 #endif
  67
  68 #ifdef CONFIG_KERNEL_XZ
  69 #include "../../../../lib/decompress_unxz.c"
  70 #endif
  71
  72 #ifdef CONFIG_KERNEL_LZO
  73 #include "../../../../lib/decompress_unlzo.c"
  74 #endif
  75
  76 #ifdef CONFIG_KERNEL_LZ4
  77 #include "../../../../lib/decompress_unlz4.c"
  78 #endif
  79 /*
  80  * NOTE: When adding a new decompressor, please update the analysis in
  81  * ../header.S.
  82  */
  83
  84 static void scroll(void)
  85 {
  86         int i;
  87
  88         memmove(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
  89         for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
  90                 vidmem[i] = ' ';
  91 }
  92
  93 #define XMTRDY          0x20
  94
  95 #define TXR             0       /*  Transmit register (WRITE) */
  96 #define LSR             5       /*  Line Status               */
  97 static void serial_putchar(int ch)
  98 {
  99         unsigned timeout = 0xffff;
 100
 101         while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
 102                 cpu_relax();
 103
 104         outb(ch, early_serial_base + TXR);
 105 }
 106
 107 void __putstr(const char *s)
 108 {
 109         int x, y, pos;
 110         char c;
 111
 112         if (early_serial_base) {
 113                 const char *str = s;
 114                 while (*str) {
 115                         if (*str == '\n')
 116                                 serial_putchar('\r');
 117                         serial_putchar(*str++);
 118                 }
 119         }
 120
 121         if (lines == 0 || cols == 0)
 122                 return;
 123
 124         x = boot_params->screen_info.orig_x;
 125         y = boot_params->screen_info.orig_y;
 126
 127         while ((c = *s++) != '\0') {
 128                 if (c == '\n') {
 129                         x = 0;
 130                         if (++y >= lines) {
 131                                 scroll();
 132                                 y--;
 133                         }
 134                 } else {
 135                         vidmem[(x + cols * y) * 2] = c;
 136                         if (++x >= cols) {
 137                                 x = 0;
 138                                 if (++y >= lines) {
 139                                         scroll();
 140                                         y--;
 141                                 }
 142                         }
 143                 }
 144         }
 145
 146         boot_params->screen_info.orig_x = x;
 147         boot_params->screen_info.orig_y = y;
 148
 149         pos = (x + cols * y) * 2;       /* Update cursor position */
 150         outb(14, vidport);
 151         outb(0xff & (pos >> 9), vidport+1);
 152         outb(15, vidport);
 153         outb(0xff & (pos >> 1), vidport+1);
 154 }
 155
 156 void __puthex(unsigned long value)
 157 {
 158         char alpha[2] = "0";
 159         int bits;
 160
 161         for (bits = sizeof(value) * 8 - 4; bits >= 0; bits -= 4) {
 162                 unsigned long digit = (value >> bits) & 0xf;
 163
 164                 if (digit < 0xA)
 165                         alpha[0] = '0' + digit;
 166                 else
 167                         alpha[0] = 'a' + (digit - 0xA);
 168
 169                 __putstr(alpha);
 170         }
 171 }
 172
 173 #if CONFIG_X86_NEED_RELOCS
 174 static void handle_relocations(void *output, unsigned long output_len,
 175                                unsigned long virt_addr)
 176 {
 177         int *reloc;
 178         unsigned long delta, map, ptr;
 179         unsigned long min_addr = (unsigned long)output;
 180         unsigned long max_addr = min_addr + (VO___bss_start - VO__text);
 181
 182         /*
 183          * Calculate the delta between where vmlinux was linked to load
 184          * and where it was actually loaded.
 185          */
 186         delta = min_addr - LOAD_PHYSICAL_ADDR;
 187
 188         /*
 189          * The kernel contains a table of relocation addresses. Those
 190          * addresses have the final load address of the kernel in virtual
 191          * memory. We are currently working in the self map. So we need to
 192          * create an adjustment for kernel memory addresses to the self map.
 193          * This will involve subtracting out the base address of the kernel.
 194          */
 195         map = delta - __START_KERNEL_map;
 196
 197         /*
 198          * 32-bit always performs relocations. 64-bit relocations are only
 199          * needed if KASLR has chosen a different starting address offset
 200          * from __START_KERNEL_map.
 201          */
 202         if (IS_ENABLED(CONFIG_X86_64))
 203                 delta = virt_addr - LOAD_PHYSICAL_ADDR;
 204
 205         if (!delta) {
 206                 debug_putstr("No relocation needed... ");
 207                 return;
 208         }
 209         debug_putstr("Performing relocations... ");
 210
 211         /*
 212          * Process relocations: 32 bit relocations first then 64 bit after.
 213          * Three sets of binary relocations are added to the end of the kernel
 214          * before compression. Each relocation table entry is the kernel
 215          * address of the location which needs to be updated stored as a
 216          * 32-bit value which is sign extended to 64 bits.
 217          *
 218          * Format is:
 219          *
 220          * kernel bits...
 221          * 0 - zero terminator for 64 bit relocations
 222          * 64 bit relocation repeated
 223          * 0 - zero terminator for inverse 32 bit relocations
 224          * 32 bit inverse relocation repeated
 225          * 0 - zero terminator for 32 bit relocations
 226          * 32 bit relocation repeated
 227          *
 228          * So we work backwards from the end of the decompressed image.
 229          */
 230         for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) {
 231                 long extended = *reloc;
 232                 extended += map;
 233
 234                 ptr = (unsigned long)extended;
 235                 if (ptr < min_addr || ptr > max_addr)
 236                         error("32-bit relocation outside of kernel!\n");
 237
 238                 *(uint32_t *)ptr += delta;
 239         }
 240 #ifdef CONFIG_X86_64
 241         while (*--reloc) {
 242                 long extended = *reloc;
 243                 extended += map;
 244
 245                 ptr = (unsigned long)extended;
 246                 if (ptr < min_addr || ptr > max_addr)
 247                         error("inverse 32-bit relocation outside of kernel!\n");
 248
 249                 *(int32_t *)ptr -= delta;
 250         }
 251         for (reloc--; *reloc; reloc--) {
 252                 long extended = *reloc;
 253                 extended += map;
 254
 255                 ptr = (unsigned long)extended;
 256                 if (ptr < min_addr || ptr > max_addr)
 257                         error("64-bit relocation outside of kernel!\n");
 258
 259                 *(uint64_t *)ptr += delta;
 260         }
 261 #endif
 262 }
 263 #else
 264 static inline void handle_relocations(void *output, unsigned long output_len,
 265                                       unsigned long virt_addr)
 266 { }
 267 #endif
 268
 269 static void parse_elf(void *output)
 270 {
 271 #ifdef CONFIG_X86_64
 272         Elf64_Ehdr ehdr;
 273         Elf64_Phdr *phdrs, *phdr;
 274 #else
 275         Elf32_Ehdr ehdr;
 276         Elf32_Phdr *phdrs, *phdr;
 277 #endif
 278         void *dest;
 279         int i;
 280
 281         memcpy(&ehdr, output, sizeof(ehdr));
 282         if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
 283            ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
 284            ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
 285            ehdr.e_ident[EI_MAG3] != ELFMAG3) {
 286                 error("Kernel is not a valid ELF file");
 287                 return;
 288         }
 289
 290         debug_putstr("Parsing ELF... ");
 291
 292         phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
 293         if (!phdrs)
 294                 error("Failed to allocate space for phdrs");
 295
 296         memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
 297
 298         for (i = 0; i < ehdr.e_phnum; i++) {
 299                 phdr = &phdrs[i];
 300
 301                 switch (phdr->p_type) {
 302                 case PT_LOAD:
 303 #ifdef CONFIG_RELOCATABLE
 304                         dest = output;
 305                         dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
 306 #else
 307                         dest = (void *)(phdr->p_paddr);
 308 #endif
 309                         memmove(dest, output + phdr->p_offset, phdr->p_filesz);
 310                         break;
 311                 default: /* Ignore other PT_* */ break;
 312                 }
 313         }
 314
 315         free(phdrs);
 316 }
 317
 318 /*
 319  * The compressed kernel image (ZO), has been moved so that its position
 320  * is against the end of the buffer used to hold the uncompressed kernel
 321  * image (VO) and the execution environment (.bss, .brk), which makes sure
 322  * there is room to do the in-place decompression. (See header.S for the
 323  * calculations.)
 324  *
 325  *                             |-----compressed kernel image------|
 326  *                             V                                  V
 327  * 0                       extract_offset                      +INIT_SIZE
 328  * |-----------|---------------|-------------------------|--------|
 329  *             |               |                         |        |
 330  *           VO__text      startup_32 of ZO          VO__end    ZO__end
 331  *             ^                                         ^
 332  *             |-------uncompressed kernel image---------|
 333  *
 334  */
 335 asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
 336                                   unsigned char *input_data,
 337                                   unsigned long input_len,
 338                                   unsigned char *output,
 339                                   unsigned long output_len)
 340 {
 341         const unsigned long kernel_total_size = VO__end - VO__text;
 342         unsigned long virt_addr = LOAD_PHYSICAL_ADDR;
 343
 344         /* Retain x86 boot parameters pointer passed from startup_32/64. */
 345         boot_params = rmode;
 346
 347         /* Clear flags intended for solely in-kernel use. */
 348         boot_params->hdr.loadflags &= ~KASLR_FLAG;
 349
 350         sanitize_boot_params(boot_params);
 351
 352         if (boot_params->screen_info.orig_video_mode == 7) {
 353                 vidmem = (char *) 0xb0000;
 354                 vidport = 0x3b4;
 355         } else {
 356                 vidmem = (char *) 0xb8000;
 357                 vidport = 0x3d4;
 358         }
 359
 360         lines = boot_params->screen_info.orig_video_lines;
 361         cols = boot_params->screen_info.orig_video_cols;
 362
 363         console_init();
 364         debug_putstr("early console in extract_kernel\n");
 365
 366         free_mem_ptr     = heap;        /* Heap */
 367         free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
 368
 369         /* Report initial kernel position details. */
 370         debug_putaddr(input_data);
 371         debug_putaddr(input_len);
 372         debug_putaddr(output);
 373         debug_putaddr(output_len);
 374         debug_putaddr(kernel_total_size);
 375
 376 #ifdef CONFIG_X86_64
 377         /* Report address of 32-bit trampoline */
 378         debug_putaddr(trampoline_32bit);
 379 #endif
 380
 381         /*
 382          * The memory hole needed for the kernel is the larger of either
 383          * the entire decompressed kernel plus relocation table, or the
 384          * entire decompressed kernel plus .bss and .brk sections.
 385          */
 386         choose_random_location((unsigned long)input_data, input_len,
 387                                 (unsigned long *)&output,
 388                                 max(output_len, kernel_total_size),
 389                                 &virt_addr);
 390
 391         /* Validate memory location choices. */
 392         if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
 393                 error("Destination physical address inappropriately aligned");
 394         if (virt_addr & (MIN_KERNEL_ALIGN - 1))
 395                 error("Destination virtual address inappropriately aligned");
 396 #ifdef CONFIG_X86_64
 397         if (heap > 0x3fffffffffffUL)
 398                 error("Destination address too large");
 399         if (virt_addr + max(output_len, kernel_total_size) > KERNEL_IMAGE_SIZE)
 400                 error("Destination virtual address is beyond the kernel mapping area");
 401 #else
 402         if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
 403                 error("Destination address too large");
 404 #endif
 405 #ifndef CONFIG_RELOCATABLE
 406         if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
 407                 error("Destination address does not match LOAD_PHYSICAL_ADDR");
 408         if (virt_addr != LOAD_PHYSICAL_ADDR)
 409                 error("Destination virtual address changed when not relocatable");
 410 #endif
 411
 412         debug_putstr("\nDecompressing Linux... ");
 413         __decompress(input_data, input_len, NULL, NULL, output, output_len,
 414                         NULL, error);
 415         parse_elf(output);
 416         handle_relocations(output, output_len, virt_addr);
 417         debug_putstr("done.\nBooting the kernel.\n");
 418         return output;
 419 }
 420
 421 void fortify_panic(const char *name)
 422 {
 423         error("detected buffer overflow");
 424 }