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 "../string.h"
  18 #include "../voffset.h"
  19
  20 /*
  21  * WARNING!!
  22  * This code is compiled with -fPIC and it is relocated dynamically at
  23  * run time, but no relocation processing is performed. This means that
  24  * it is not safe to place pointers in static structures.
  25  */
  26
  27 /* Macros used by the included decompressor code below. */
  28 #define STATIC          static
  29
  30 /*
  31  * Use normal definitions of mem*() from string.c. There are already
  32  * included header files which expect a definition of memset() and by
  33  * the time we define memset macro, it is too late.
  34  */
  35 #undef memcpy
  36 #undef memset
  37 #define memzero(s, n)   memset((s), 0, (n))
  38 #define memmove         memmove
  39
  40 /* Functions used by the included decompressor code below. */
  41 void *memmove(void *dest, const void *src, size_t n);
  42
  43 /*
  44  * This is set up by the setup-routine at boot-time
  45  */
  46 struct boot_params *boot_params;
  47
  48 memptr free_mem_ptr;
  49 memptr free_mem_end_ptr;
  50
  51 static char *vidmem;
  52 static int vidport;
  53 static int lines, cols;
  54
  55 #ifdef CONFIG_KERNEL_GZIP
  56 #include "../../../../lib/decompress_inflate.c"
  57 #endif
  58
  59 #ifdef CONFIG_KERNEL_BZIP2
  60 #include "../../../../lib/decompress_bunzip2.c"
  61 #endif
  62
  63 #ifdef CONFIG_KERNEL_LZMA
  64 #include "../../../../lib/decompress_unlzma.c"
  65 #endif
  66
  67 #ifdef CONFIG_KERNEL_XZ
  68 #include "../../../../lib/decompress_unxz.c"
  69 #endif
  70
  71 #ifdef CONFIG_KERNEL_LZO
  72 #include "../../../../lib/decompress_unlzo.c"
  73 #endif
  74
  75 #ifdef CONFIG_KERNEL_LZ4
  76 #include "../../../../lib/decompress_unlz4.c"
  77 #endif
  78 /*
  79  * NOTE: When adding a new decompressor, please update the analysis in
  80  * ../header.S.
  81  */
  82
  83 static void scroll(void)
  84 {
  85         int i;
  86
  87         memmove(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
  88         for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
  89                 vidmem[i] = ' ';
  90 }
  91
  92 #define XMTRDY          0x20
  93
  94 #define TXR             0       /*  Transmit register (WRITE) */
  95 #define LSR             5       /*  Line Status               */
  96 static void serial_putchar(int ch)
  97 {
  98         unsigned timeout = 0xffff;
  99
 100         while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
 101                 cpu_relax();
 102
 103         outb(ch, early_serial_base + TXR);
 104 }
 105
 106 void __putstr(const char *s)
 107 {
 108         int x, y, pos;
 109         char c;
 110
 111         if (early_serial_base) {
 112                 const char *str = s;
 113                 while (*str) {
 114                         if (*str == '\n')
 115                                 serial_putchar('\r');
 116                         serial_putchar(*str++);
 117                 }
 118         }
 119
 120         if (lines == 0 || cols == 0)
 121                 return;
 122
 123         x = boot_params->screen_info.orig_x;
 124         y = boot_params->screen_info.orig_y;
 125
 126         while ((c = *s++) != '\0') {
 127                 if (c == '\n') {
 128                         x = 0;
 129                         if (++y >= lines) {
 130                                 scroll();
 131                                 y--;
 132                         }
 133                 } else {
 134                         vidmem[(x + cols * y) * 2] = c;
 135                         if (++x >= cols) {
 136                                 x = 0;
 137                                 if (++y >= lines) {
 138                                         scroll();
 139                                         y--;
 140                                 }
 141                         }
 142                 }
 143         }
 144
 145         boot_params->screen_info.orig_x = x;
 146         boot_params->screen_info.orig_y = y;
 147
 148         pos = (x + cols * y) * 2;       /* Update cursor position */
 149         outb(14, vidport);
 150         outb(0xff & (pos >> 9), vidport+1);
 151         outb(15, vidport);
 152         outb(0xff & (pos >> 1), vidport+1);
 153 }
 154
 155 void __puthex(unsigned long value)
 156 {
 157         char alpha[2] = "0";
 158         int bits;
 159
 160         for (bits = sizeof(value) * 8 - 4; bits >= 0; bits -= 4) {
 161                 unsigned long digit = (value >> bits) & 0xf;
 162
 163                 if (digit < 0xA)
 164                         alpha[0] = '0' + digit;
 165                 else
 166                         alpha[0] = 'a' + (digit - 0xA);
 167
 168                 __putstr(alpha);
 169         }
 170 }
 171
 172 static bool l5_supported(void)
 173 {
 174         /* Check if leaf 7 is supported. */
 175         if (native_cpuid_eax(0) < 7)
 176                 return 0;
 177
 178         /* Check if la57 is supported. */
 179         return native_cpuid_ecx(7) & (1 << (X86_FEATURE_LA57 & 31));
 180 }
 181
 182 #if CONFIG_X86_NEED_RELOCS
 183 static void handle_relocations(void *output, unsigned long output_len,
 184                                unsigned long virt_addr)
 185 {
 186         int *reloc;
 187         unsigned long delta, map, ptr;
 188         unsigned long min_addr = (unsigned long)output;
 189         unsigned long max_addr = min_addr + (VO___bss_start - VO__text);
 190
 191         /*
 192          * Calculate the delta between where vmlinux was linked to load
 193          * and where it was actually loaded.
 194          */
 195         delta = min_addr - LOAD_PHYSICAL_ADDR;
 196
 197         /*
 198          * The kernel contains a table of relocation addresses. Those
 199          * addresses have the final load address of the kernel in virtual
 200          * memory. We are currently working in the self map. So we need to
 201          * create an adjustment for kernel memory addresses to the self map.
 202          * This will involve subtracting out the base address of the kernel.
 203          */
 204         map = delta - __START_KERNEL_map;
 205
 206         /*
 207          * 32-bit always performs relocations. 64-bit relocations are only
 208          * needed if KASLR has chosen a different starting address offset
 209          * from __START_KERNEL_map.
 210          */
 211         if (IS_ENABLED(CONFIG_X86_64))
 212                 delta = virt_addr - LOAD_PHYSICAL_ADDR;
 213
 214         if (!delta) {
 215                 debug_putstr("No relocation needed... ");
 216                 return;
 217         }
 218         debug_putstr("Performing relocations... ");
 219
 220         /*
 221          * Process relocations: 32 bit relocations first then 64 bit after.
 222          * Three sets of binary relocations are added to the end of the kernel
 223          * before compression. Each relocation table entry is the kernel
 224          * address of the location which needs to be updated stored as a
 225          * 32-bit value which is sign extended to 64 bits.
 226          *
 227          * Format is:
 228          *
 229          * kernel bits...
 230          * 0 - zero terminator for 64 bit relocations
 231          * 64 bit relocation repeated
 232          * 0 - zero terminator for inverse 32 bit relocations
 233          * 32 bit inverse relocation repeated
 234          * 0 - zero terminator for 32 bit relocations
 235          * 32 bit relocation repeated
 236          *
 237          * So we work backwards from the end of the decompressed image.
 238          */
 239         for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) {
 240                 long extended = *reloc;
 241                 extended += map;
 242
 243                 ptr = (unsigned long)extended;
 244                 if (ptr < min_addr || ptr > max_addr)
 245                         error("32-bit relocation outside of kernel!\n");
 246
 247                 *(uint32_t *)ptr += delta;
 248         }
 249 #ifdef CONFIG_X86_64
 250         while (*--reloc) {
 251                 long extended = *reloc;
 252                 extended += map;
 253
 254                 ptr = (unsigned long)extended;
 255                 if (ptr < min_addr || ptr > max_addr)
 256                         error("inverse 32-bit relocation outside of kernel!\n");
 257
 258                 *(int32_t *)ptr -= delta;
 259         }
 260         for (reloc--; *reloc; reloc--) {
 261                 long extended = *reloc;
 262                 extended += map;
 263
 264                 ptr = (unsigned long)extended;
 265                 if (ptr < min_addr || ptr > max_addr)
 266                         error("64-bit relocation outside of kernel!\n");
 267
 268                 *(uint64_t *)ptr += delta;
 269         }
 270 #endif
 271 }
 272 #else
 273 static inline void handle_relocations(void *output, unsigned long output_len,
 274                                       unsigned long virt_addr)
 275 { }
 276 #endif
 277
 278 static void parse_elf(void *output)
 279 {
 280 #ifdef CONFIG_X86_64
 281         Elf64_Ehdr ehdr;
 282         Elf64_Phdr *phdrs, *phdr;
 283 #else
 284         Elf32_Ehdr ehdr;
 285         Elf32_Phdr *phdrs, *phdr;
 286 #endif
 287         void *dest;
 288         int i;
 289
 290         memcpy(&ehdr, output, sizeof(ehdr));
 291         if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
 292            ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
 293            ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
 294            ehdr.e_ident[EI_MAG3] != ELFMAG3) {
 295                 error("Kernel is not a valid ELF file");
 296                 return;
 297         }
 298
 299         debug_putstr("Parsing ELF... ");
 300
 301         phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
 302         if (!phdrs)
 303                 error("Failed to allocate space for phdrs");
 304
 305         memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
 306
 307         for (i = 0; i < ehdr.e_phnum; i++) {
 308                 phdr = &phdrs[i];
 309
 310                 switch (phdr->p_type) {
 311                 case PT_LOAD:
 312 #ifdef CONFIG_RELOCATABLE
 313                         dest = output;
 314                         dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
 315 #else
 316                         dest = (void *)(phdr->p_paddr);
 317 #endif
 318                         memmove(dest, output + phdr->p_offset, phdr->p_filesz);
 319                         break;
 320                 default: /* Ignore other PT_* */ break;
 321                 }
 322         }
 323
 324         free(phdrs);
 325 }
 326
 327 /*
 328  * The compressed kernel image (ZO), has been moved so that its position
 329  * is against the end of the buffer used to hold the uncompressed kernel
 330  * image (VO) and the execution environment (.bss, .brk), which makes sure
 331  * there is room to do the in-place decompression. (See header.S for the
 332  * calculations.)
 333  *
 334  *                             |-----compressed kernel image------|
 335  *                             V                                  V
 336  * 0                       extract_offset                      +INIT_SIZE
 337  * |-----------|---------------|-------------------------|--------|
 338  *             |               |                         |        |
 339  *           VO__text      startup_32 of ZO          VO__end    ZO__end
 340  *             ^                                         ^
 341  *             |-------uncompressed kernel image---------|
 342  *
 343  */
 344 asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
 345                                   unsigned char *input_data,
 346                                   unsigned long input_len,
 347                                   unsigned char *output,
 348                                   unsigned long output_len)
 349 {
 350         const unsigned long kernel_total_size = VO__end - VO__text;
 351         unsigned long virt_addr = LOAD_PHYSICAL_ADDR;
 352
 353         /* Retain x86 boot parameters pointer passed from startup_32/64. */
 354         boot_params = rmode;
 355
 356         /* Clear flags intended for solely in-kernel use. */
 357         boot_params->hdr.loadflags &= ~KASLR_FLAG;
 358
 359         sanitize_boot_params(boot_params);
 360
 361         if (boot_params->screen_info.orig_video_mode == 7) {
 362                 vidmem = (char *) 0xb0000;
 363                 vidport = 0x3b4;
 364         } else {
 365                 vidmem = (char *) 0xb8000;
 366                 vidport = 0x3d4;
 367         }
 368
 369         lines = boot_params->screen_info.orig_video_lines;
 370         cols = boot_params->screen_info.orig_video_cols;
 371
 372         console_init();
 373         debug_putstr("early console in extract_kernel\n");
 374
 375         if (IS_ENABLED(CONFIG_X86_5LEVEL) && !l5_supported()) {
 376                 error("This linux kernel as configured requires 5-level paging\n"
 377                         "This CPU does not support the required 'cr4.la57' feature\n"
 378                         "Unable to boot - please use a kernel appropriate for your CPU\n");
 379         }
 380
 381         free_mem_ptr     = heap;        /* Heap */
 382         free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
 383
 384         /* Report initial kernel position details. */
 385         debug_putaddr(input_data);
 386         debug_putaddr(input_len);
 387         debug_putaddr(output);
 388         debug_putaddr(output_len);
 389         debug_putaddr(kernel_total_size);
 390
 391         /*
 392          * The memory hole needed for the kernel is the larger of either
 393          * the entire decompressed kernel plus relocation table, or the
 394          * entire decompressed kernel plus .bss and .brk sections.
 395          */
 396         choose_random_location((unsigned long)input_data, input_len,
 397                                 (unsigned long *)&output,
 398                                 max(output_len, kernel_total_size),
 399                                 &virt_addr);
 400
 401         /* Validate memory location choices. */
 402         if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
 403                 error("Destination physical address inappropriately aligned");
 404         if (virt_addr & (MIN_KERNEL_ALIGN - 1))
 405                 error("Destination virtual address inappropriately aligned");
 406 #ifdef CONFIG_X86_64
 407         if (heap > 0x3fffffffffffUL)
 408                 error("Destination address too large");
 409         if (virt_addr + max(output_len, kernel_total_size) > KERNEL_IMAGE_SIZE)
 410                 error("Destination virtual address is beyond the kernel mapping area");
 411 #else
 412         if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
 413                 error("Destination address too large");
 414 #endif
 415 #ifndef CONFIG_RELOCATABLE
 416         if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
 417                 error("Destination address does not match LOAD_PHYSICAL_ADDR");
 418         if (virt_addr != LOAD_PHYSICAL_ADDR)
 419                 error("Destination virtual address changed when not relocatable");
 420 #endif
 421
 422         debug_putstr("\nDecompressing Linux... ");
 423         __decompress(input_data, input_len, NULL, NULL, output, output_len,
 424                         NULL, error);
 425         parse_elf(output);
 426         handle_relocations(output, output_len, virt_addr);
 427         debug_putstr("done.\nBooting the kernel.\n");
 428         return output;
 429 }
 430
 431 void fortify_panic(const char *name)
 432 {
 433         error("detected buffer overflow");
 434 }