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 #include <asm/bootparam_utils.h>
21
22 /*
23 * WARNING!!
24 * This code is compiled with -fPIC and it is relocated dynamically at
25 * run time, but no relocation processing is performed. This means that
26 * it is not safe to place pointers in static structures.
27 */
28
29 /* Macros used by the included decompressor code below. */
30 #define STATIC static
31 /* Define an externally visible malloc()/free(). */
32 #define MALLOC_VISIBLE
33 #include <linux/decompress/mm.h>
34
35 /*
36 * Provide definitions of memzero and memmove as some of the decompressors will
37 * try to define their own functions if these are not defined as macros.
38 */
39 #define memzero(s, n) memset((s), 0, (n))
40 #ifndef memmove
41 #define memmove memmove
42 /* Functions used by the included decompressor code below. */
43 void *memmove(void *dest, const void *src, size_t n);
44 #endif
45
46 /*
47 * This is set up by the setup-routine at boot-time
48 */
49 struct boot_params *boot_params_ptr;
50
51 struct port_io_ops pio_ops;
52
53 memptr free_mem_ptr;
54 memptr free_mem_end_ptr;
55 int spurious_nmi_count;
56
57 static char *vidmem;
58 static int vidport;
59
60 /* These might be accessed before .bss is cleared, so use .data instead. */
61 static int lines __section(".data");
62 static int cols __section(".data");
63
64 #ifdef CONFIG_KERNEL_GZIP
65 #include "../../../../lib/decompress_inflate.c"
66 #endif
67
68 #ifdef CONFIG_KERNEL_BZIP2
69 #include "../../../../lib/decompress_bunzip2.c"
70 #endif
71
72 #ifdef CONFIG_KERNEL_LZMA
73 #include "../../../../lib/decompress_unlzma.c"
74 #endif
75
76 #ifdef CONFIG_KERNEL_XZ
77 #include "../../../../lib/decompress_unxz.c"
78 #endif
79
80 #ifdef CONFIG_KERNEL_LZO
81 #include "../../../../lib/decompress_unlzo.c"
82 #endif
83
84 #ifdef CONFIG_KERNEL_LZ4
85 #include "../../../../lib/decompress_unlz4.c"
86 #endif
87
88 #ifdef CONFIG_KERNEL_ZSTD
89 #include "../../../../lib/decompress_unzstd.c"
90 #endif
91 /*
92 * NOTE: When adding a new decompressor, please update the analysis in
93 * ../header.S.
94 */
95
96 static void scroll(void)
97 {
98 int i;
99
100 memmove(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
101 for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
102 vidmem[i] = ' ';
103 }
104
105 #define XMTRDY 0x20
106
107 #define TXR 0 /* Transmit register (WRITE) */
108 #define LSR 5 /* Line Status */
109 static void serial_putchar(int ch)
110 {
111 unsigned timeout = 0xffff;
112
113 while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
114 cpu_relax();
115
116 outb(ch, early_serial_base + TXR);
117 }
118
119 void __putstr(const char *s)
120 {
121 int x, y, pos;
122 char c;
123
124 if (early_serial_base) {
125 const char *str = s;
126 while (*str) {
127 if (*str == '\n')
128 serial_putchar('\r');
129 serial_putchar(*str++);
130 }
131 }
132
133 if (lines == 0 || cols == 0)
134 return;
135
136 x = boot_params_ptr->screen_info.orig_x;
137 y = boot_params_ptr->screen_info.orig_y;
138
139 while ((c = *s++) != '\0') {
140 if (c == '\n') {
141 x = 0;
142 if (++y >= lines) {
143 scroll();
144 y--;
145 }
146 } else {
147 vidmem[(x + cols * y) * 2] = c;
148 if (++x >= cols) {
149 x = 0;
150 if (++y >= lines) {
151 scroll();
152 y--;
153 }
154 }
155 }
156 }
157
158 boot_params_ptr->screen_info.orig_x = x;
159 boot_params_ptr->screen_info.orig_y = y;
160
161 pos = (x + cols * y) * 2; /* Update cursor position */
162 outb(14, vidport);
163 outb(0xff & (pos >> 9), vidport+1);
164 outb(15, vidport);
165 outb(0xff & (pos >> 1), vidport+1);
166 }
167
168 static noinline void __putnum(unsigned long value, unsigned int base,
169 int mindig)
170 {
171 char buf[8*sizeof(value)+1];
172 char *p;
173
174 p = buf + sizeof(buf);
175 *--p = '\0';
176
177 while (mindig-- > 0 || value) {
178 unsigned char digit = value % base;
179 digit += (digit >= 10) ? ('a'-10) : '';
180 *--p = digit;
181
182 value /= base;
183 }
184
185 __putstr(p);
186 }
187
188 void __puthex(unsigned long value)
189 {
190 __putnum(value, 16, sizeof(value)*2);
191 }
192
193 void __putdec(unsigned long value)
194 {
195 __putnum(value, 10, 1);
196 }
197
198 #ifdef CONFIG_X86_NEED_RELOCS
199 static void handle_relocations(void *output, unsigned long output_len,
200 unsigned long virt_addr)
201 {
202 int *reloc;
203 unsigned long delta, map, ptr;
204 unsigned long min_addr = (unsigned long)output;
205 unsigned long max_addr = min_addr + (VO___bss_start - VO__text);
206
207 /*
208 * Calculate the delta between where vmlinux was linked to load
209 * and where it was actually loaded.
210 */
211 delta = min_addr - LOAD_PHYSICAL_ADDR;
212
213 /*
214 * The kernel contains a table of relocation addresses. Those
215 * addresses have the final load address of the kernel in virtual
216 * memory. We are currently working in the self map. So we need to
217 * create an adjustment for kernel memory addresses to the self map.
218 * This will involve subtracting out the base address of the kernel.
219 */
220 map = delta - __START_KERNEL_map;
221
222 /*
223 * 32-bit always performs relocations. 64-bit relocations are only
224 * needed if KASLR has chosen a different starting address offset
225 * from __START_KERNEL_map.
226 */
227 if (IS_ENABLED(CONFIG_X86_64))
228 delta = virt_addr - LOAD_PHYSICAL_ADDR;
229
230 if (!delta) {
231 debug_putstr("No relocation needed... ");
232 return;
233 }
234 debug_putstr("Performing relocations... ");
235
236 /*
237 * Process relocations: 32 bit relocations first then 64 bit after.
238 * Three sets of binary relocations are added to the end of the kernel
239 * before compression. Each relocation table entry is the kernel
240 * address of the location which needs to be updated stored as a
241 * 32-bit value which is sign extended to 64 bits.
242 *
243 * Format is:
244 *
245 * kernel bits...
246 * 0 - zero terminator for 64 bit relocations
247 * 64 bit relocation repeated
248 * 0 - zero terminator for inverse 32 bit relocations
249 * 32 bit inverse relocation repeated
250 * 0 - zero terminator for 32 bit relocations
251 * 32 bit relocation repeated
252 *
253 * So we work backwards from the end of the decompressed image.
254 */
255 for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) {
256 long extended = *reloc;
257 extended += map;
258
259 ptr = (unsigned long)extended;
260 if (ptr < min_addr || ptr > max_addr)
261 error("32-bit relocation outside of kernel!\n");
262
263 *(uint32_t *)ptr += delta;
264 }
265 #ifdef CONFIG_X86_64
266 while (*--reloc) {
267 long extended = *reloc;
268 extended += map;
269
270 ptr = (unsigned long)extended;
271 if (ptr < min_addr || ptr > max_addr)
272 error("inverse 32-bit relocation outside of kernel!\n");
273
274 *(int32_t *)ptr -= delta;
275 }
276 for (reloc--; *reloc; reloc--) {
277 long extended = *reloc;
278 extended += map;
279
280 ptr = (unsigned long)extended;
281 if (ptr < min_addr || ptr > max_addr)
282 error("64-bit relocation outside of kernel!\n");
283
284 *(uint64_t *)ptr += delta;
285 }
286 #endif
287 }
288 #else
289 static inline void handle_relocations(void *output, unsigned long output_len,
290 unsigned long virt_addr)
291 { }
292 #endif
293
294 static size_t parse_elf(void *output)
295 {
296 #ifdef CONFIG_X86_64
297 Elf64_Ehdr ehdr;
298 Elf64_Phdr *phdrs, *phdr;
299 #else
300 Elf32_Ehdr ehdr;
301 Elf32_Phdr *phdrs, *phdr;
302 #endif
303 void *dest;
304 int i;
305
306 memcpy(&ehdr, output, sizeof(ehdr));
307 if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
308 ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
309 ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
310 ehdr.e_ident[EI_MAG3] != ELFMAG3)
311 error("Kernel is not a valid ELF file");
312
313 debug_putstr("Parsing ELF... ");
314
315 phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
316 if (!phdrs)
317 error("Failed to allocate space for phdrs");
318
319 memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
320
321 for (i = 0; i < ehdr.e_phnum; i++) {
322 phdr = &phdrs[i];
323
324 switch (phdr->p_type) {
325 case PT_LOAD:
326 #ifdef CONFIG_X86_64
327 if ((phdr->p_align % 0x200000) != 0)
328 error("Alignment of LOAD segment isn't multiple of 2MB");
329 #endif
330 #ifdef CONFIG_RELOCATABLE
331 dest = output;
332 dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
333 #else
334 dest = (void *)(phdr->p_paddr);
335 #endif
336 memmove(dest, output + phdr->p_offset, phdr->p_filesz);
337 break;
338 default: /* Ignore other PT_* */ break;
339 }
340 }
341
342 free(phdrs);
343
344 return ehdr.e_entry - LOAD_PHYSICAL_ADDR;
345 }
346
347 const unsigned long kernel_text_size = VO___start_rodata - VO__text;
348 const unsigned long kernel_total_size = VO__end - VO__text;
349
350 static u8 boot_heap[BOOT_HEAP_SIZE] __aligned(4);
351
352 extern unsigned char input_data[];
353 extern unsigned int input_len, output_len;
354
355 unsigned long decompress_kernel(unsigned char *outbuf, unsigned long virt_addr,
356 void (*error)(char *x))
357 {
358 unsigned long entry;
359
360 if (!free_mem_ptr) {
361 free_mem_ptr = (unsigned long)boot_heap;
362 free_mem_end_ptr = (unsigned long)boot_heap + sizeof(boot_heap);
363 }
364
365 if (__decompress(input_data, input_len, NULL, NULL, outbuf, output_len,
366 NULL, error) < 0)
367 return ULONG_MAX;
368
369 entry = parse_elf(outbuf);
370 handle_relocations(outbuf, output_len, virt_addr);
371
372 return entry;
373 }
374
375 /*
376 * Set the memory encryption xloadflag based on the mem_encrypt= command line
377 * parameter, if provided.
378 */
379 static void parse_mem_encrypt(struct setup_header *hdr)
380 {
381 int on = cmdline_find_option_bool("mem_encrypt=on");
382 int off = cmdline_find_option_bool("mem_encrypt=off");
383
384 if (on > off)
385 hdr->xloadflags |= XLF_MEM_ENCRYPTION;
386 }
387
388 /*
389 * The compressed kernel image (ZO), has been moved so that its position
390 * is against the end of the buffer used to hold the uncompressed kernel
391 * image (VO) and the execution environment (.bss, .brk), which makes sure
392 * there is room to do the in-place decompression. (See header.S for the
393 * calculations.)
394 *
395 * |-----compressed kernel image------|
396 * V V
397 * 0 extract_offset +INIT_SIZE
398 * |-----------|---------------|-------------------------|--------|
399 * | | | |
400 * VO__text startup_32 of ZO VO__end ZO__end
401 * ^ ^
402 * |-------uncompressed kernel image---------|
403 *
404 */
405 asmlinkage __visible void *extract_kernel(void *rmode, unsigned char *output)
406 {
407 unsigned long virt_addr = LOAD_PHYSICAL_ADDR;
408 memptr heap = (memptr)boot_heap;
409 unsigned long needed_size;
410 size_t entry_offset;
411
412 /* Retain x86 boot parameters pointer passed from startup_32/64. */
413 boot_params_ptr = rmode;
414
415 /* Clear flags intended for solely in-kernel use. */
416 boot_params_ptr->hdr.loadflags &= ~KASLR_FLAG;
417
418 parse_mem_encrypt(&boot_params_ptr->hdr);
419
420 sanitize_boot_params(boot_params_ptr);
421
422 if (boot_params_ptr->screen_info.orig_video_mode == 7) {
423 vidmem = (char *) 0xb0000;
424 vidport = 0x3b4;
425 } else {
426 vidmem = (char *) 0xb8000;
427 vidport = 0x3d4;
428 }
429
430 lines = boot_params_ptr->screen_info.orig_video_lines;
431 cols = boot_params_ptr->screen_info.orig_video_cols;
432
433 init_default_io_ops();
434
435 /*
436 * Detect TDX guest environment.
437 *
438 * It has to be done before console_init() in order to use
439 * paravirtualized port I/O operations if needed.
440 */
441 early_tdx_detect();
442
443 console_init();
444
445 /*
446 * Save RSDP address for later use. Have this after console_init()
447 * so that early debugging output from the RSDP parsing code can be
448 * collected.
449 */
450 boot_params_ptr->acpi_rsdp_addr = get_rsdp_addr();
451
452 debug_putstr("early console in extract_kernel\n");
453
454 free_mem_ptr = heap; /* Heap */
455 free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
456
457 /*
458 * The memory hole needed for the kernel is the larger of either
459 * the entire decompressed kernel plus relocation table, or the
460 * entire decompressed kernel plus .bss and .brk sections.
461 *
462 * On X86_64, the memory is mapped with PMD pages. Round the
463 * size up so that the full extent of PMD pages mapped is
464 * included in the check against the valid memory table
465 * entries. This ensures the full mapped area is usable RAM
466 * and doesn't include any reserved areas.
467 */
468 needed_size = max_t(unsigned long, output_len, kernel_total_size);
469 #ifdef CONFIG_X86_64
470 needed_size = ALIGN(needed_size, MIN_KERNEL_ALIGN);
471 #endif
472
473 /* Report initial kernel position details. */
474 debug_putaddr(input_data);
475 debug_putaddr(input_len);
476 debug_putaddr(output);
477 debug_putaddr(output_len);
478 debug_putaddr(kernel_total_size);
479 debug_putaddr(needed_size);
480
481 #ifdef CONFIG_X86_64
482 /* Report address of 32-bit trampoline */
483 debug_putaddr(trampoline_32bit);
484 #endif
485
486 choose_random_location((unsigned long)input_data, input_len,
487 (unsigned long *)&output,
488 needed_size,
489 &virt_addr);
490
491 /* Validate memory location choices. */
492 if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
493 error("Destination physical address inappropriately aligned");
494 if (virt_addr & (MIN_KERNEL_ALIGN - 1))
495 error("Destination virtual address inappropriately aligned");
496 #ifdef CONFIG_X86_64
497 if (heap > 0x3fffffffffffUL)
498 error("Destination address too large");
499 if (virt_addr + needed_size > KERNEL_IMAGE_SIZE)
500 error("Destination virtual address is beyond the kernel mapping area");
501 #else
502 if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
503 error("Destination address too large");
504 #endif
505 #ifndef CONFIG_RELOCATABLE
506 if (virt_addr != LOAD_PHYSICAL_ADDR)
507 error("Destination virtual address changed when not relocatable");
508 #endif
509
510 debug_putstr("\nDecompressing Linux... ");
511
512 if (init_unaccepted_memory()) {
513 debug_putstr("Accepting memory... ");
514 accept_memory(__pa(output), __pa(output) + needed_size);
515 }
516
517 entry_offset = decompress_kernel(output, virt_addr, error);
518
519 debug_putstr("done.\nBooting the kernel (entry_offset: 0x");
520 debug_puthex(entry_offset);
521 debug_putstr(").\n");
522
523 /* Disable exception handling before booting the kernel */
524 cleanup_exception_handling();
525
526 if (spurious_nmi_count) {
527 error_putstr("Spurious early NMIs ignored: ");
528 error_putdec(spurious_nmi_count);
529 error_putstr("\n");
530 }
531
532 return output + entry_offset;
533 }
534
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