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 } 435