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
scroll(void)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 */
serial_putchar(int ch)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
__putstr(const char * s)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
__putnum(unsigned long value,unsigned int base,int mindig)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) : '0';
180 *--p = digit;
181
182 value /= base;
183 }
184
185 __putstr(p);
186 }
187
__puthex(unsigned long value)188 void __puthex(unsigned long value)
189 {
190 __putnum(value, 16, sizeof(value)*2);
191 }
192
__putdec(unsigned long value)193 void __putdec(unsigned long value)
194 {
195 __putnum(value, 10, 1);
196 }
197
198 #ifdef CONFIG_X86_NEED_RELOCS
handle_relocations(void * output,unsigned long output_len,unsigned long virt_addr)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 * Two 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 32 bit relocations
249 * 32 bit relocation repeated
250 *
251 * So we work backwards from the end of the decompressed image.
252 */
253 for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) {
254 long extended = *reloc;
255 extended += map;
256
257 ptr = (unsigned long)extended;
258 if (ptr < min_addr || ptr > max_addr)
259 error("32-bit relocation outside of kernel!\n");
260
261 *(uint32_t *)ptr += delta;
262 }
263 #ifdef CONFIG_X86_64
264 for (reloc--; *reloc; reloc--) {
265 long extended = *reloc;
266 extended += map;
267
268 ptr = (unsigned long)extended;
269 if (ptr < min_addr || ptr > max_addr)
270 error("64-bit relocation outside of kernel!\n");
271
272 *(uint64_t *)ptr += delta;
273 }
274 #endif
275 }
276 #else
handle_relocations(void * output,unsigned long output_len,unsigned long virt_addr)277 static inline void handle_relocations(void *output, unsigned long output_len,
278 unsigned long virt_addr)
279 { }
280 #endif
281
parse_elf(void * output)282 static size_t parse_elf(void *output)
283 {
284 #ifdef CONFIG_X86_64
285 Elf64_Ehdr ehdr;
286 Elf64_Phdr *phdrs, *phdr;
287 #else
288 Elf32_Ehdr ehdr;
289 Elf32_Phdr *phdrs, *phdr;
290 #endif
291 void *dest;
292 int i;
293
294 memcpy(&ehdr, output, sizeof(ehdr));
295 if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
296 ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
297 ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
298 ehdr.e_ident[EI_MAG3] != ELFMAG3)
299 error("Kernel is not a valid ELF file");
300
301 debug_putstr("Parsing ELF... ");
302
303 phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
304 if (!phdrs)
305 error("Failed to allocate space for phdrs");
306
307 memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
308
309 for (i = 0; i < ehdr.e_phnum; i++) {
310 phdr = &phdrs[i];
311
312 switch (phdr->p_type) {
313 case PT_LOAD:
314 #ifdef CONFIG_X86_64
315 if ((phdr->p_align % 0x200000) != 0)
316 error("Alignment of LOAD segment isn't multiple of 2MB");
317 #endif
318 #ifdef CONFIG_RELOCATABLE
319 dest = output;
320 dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
321 #else
322 dest = (void *)(phdr->p_paddr);
323 #endif
324 memmove(dest, output + phdr->p_offset, phdr->p_filesz);
325 break;
326 default: /* Ignore other PT_* */ break;
327 }
328 }
329
330 free(phdrs);
331
332 return ehdr.e_entry - LOAD_PHYSICAL_ADDR;
333 }
334
335 const unsigned long kernel_text_size = VO___start_rodata - VO__text;
336 const unsigned long kernel_total_size = VO__end - VO__text;
337
338 static u8 boot_heap[BOOT_HEAP_SIZE] __aligned(4);
339
340 extern unsigned char input_data[];
341 extern unsigned int input_len, output_len;
342
decompress_kernel(unsigned char * outbuf,unsigned long virt_addr,void (* error)(char * x))343 unsigned long decompress_kernel(unsigned char *outbuf, unsigned long virt_addr,
344 void (*error)(char *x))
345 {
346 unsigned long entry;
347
348 if (!free_mem_ptr) {
349 free_mem_ptr = (unsigned long)boot_heap;
350 free_mem_end_ptr = (unsigned long)boot_heap + sizeof(boot_heap);
351 }
352
353 if (__decompress(input_data, input_len, NULL, NULL, outbuf, output_len,
354 NULL, error) < 0)
355 return ULONG_MAX;
356
357 entry = parse_elf(outbuf);
358 handle_relocations(outbuf, output_len, virt_addr);
359
360 return entry;
361 }
362
363 /*
364 * Set the memory encryption xloadflag based on the mem_encrypt= command line
365 * parameter, if provided.
366 */
parse_mem_encrypt(struct setup_header * hdr)367 static void parse_mem_encrypt(struct setup_header *hdr)
368 {
369 int on = cmdline_find_option_bool("mem_encrypt=on");
370 int off = cmdline_find_option_bool("mem_encrypt=off");
371
372 if (on > off)
373 hdr->xloadflags |= XLF_MEM_ENCRYPTION;
374 }
375
early_sev_detect(void)376 static void early_sev_detect(void)
377 {
378 /*
379 * Accessing video memory causes guest termination because
380 * the boot stage2 #VC handler of SEV-ES/SNP guests does not
381 * support MMIO handling and kexec -c adds screen_info to the
382 * boot parameters passed to the kexec kernel, which causes
383 * console output to be dumped to both video and serial.
384 */
385 if (sev_status & MSR_AMD64_SEV_ES_ENABLED)
386 lines = cols = 0;
387 }
388
389 /*
390 * The compressed kernel image (ZO), has been moved so that its position
391 * is against the end of the buffer used to hold the uncompressed kernel
392 * image (VO) and the execution environment (.bss, .brk), which makes sure
393 * there is room to do the in-place decompression. (See header.S for the
394 * calculations.)
395 *
396 * |-----compressed kernel image------|
397 * V V
398 * 0 extract_offset +INIT_SIZE
399 * |-----------|---------------|-------------------------|--------|
400 * | | | |
401 * VO__text startup_32 of ZO VO__end ZO__end
402 * ^ ^
403 * |-------uncompressed kernel image---------|
404 *
405 */
extract_kernel(void * rmode,unsigned char * output)406 asmlinkage __visible void *extract_kernel(void *rmode, unsigned char *output)
407 {
408 unsigned long virt_addr = LOAD_PHYSICAL_ADDR;
409 memptr heap = (memptr)boot_heap;
410 unsigned long needed_size;
411 size_t entry_offset;
412
413 /* Retain x86 boot parameters pointer passed from startup_32/64. */
414 boot_params_ptr = rmode;
415
416 /* Clear flags intended for solely in-kernel use. */
417 boot_params_ptr->hdr.loadflags &= ~KASLR_FLAG;
418
419 parse_mem_encrypt(&boot_params_ptr->hdr);
420
421 sanitize_boot_params(boot_params_ptr);
422
423 if (boot_params_ptr->screen_info.orig_video_mode == 7) {
424 vidmem = (char *) 0xb0000;
425 vidport = 0x3b4;
426 } else {
427 vidmem = (char *) 0xb8000;
428 vidport = 0x3d4;
429 }
430
431 lines = boot_params_ptr->screen_info.orig_video_lines;
432 cols = boot_params_ptr->screen_info.orig_video_cols;
433
434 init_default_io_ops();
435
436 /*
437 * Detect TDX guest environment.
438 *
439 * It has to be done before console_init() in order to use
440 * paravirtualized port I/O operations if needed.
441 */
442 early_tdx_detect();
443
444 early_sev_detect();
445
446 console_init();
447
448 /*
449 * Save RSDP address for later use. Have this after console_init()
450 * so that early debugging output from the RSDP parsing code can be
451 * collected.
452 */
453 boot_params_ptr->acpi_rsdp_addr = get_rsdp_addr();
454
455 debug_putstr("early console in extract_kernel\n");
456
457 free_mem_ptr = heap; /* Heap */
458 free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
459
460 /*
461 * The memory hole needed for the kernel is the larger of either
462 * the entire decompressed kernel plus relocation table, or the
463 * entire decompressed kernel plus .bss and .brk sections.
464 *
465 * On X86_64, the memory is mapped with PMD pages. Round the
466 * size up so that the full extent of PMD pages mapped is
467 * included in the check against the valid memory table
468 * entries. This ensures the full mapped area is usable RAM
469 * and doesn't include any reserved areas.
470 */
471 needed_size = max_t(unsigned long, output_len, kernel_total_size);
472 #ifdef CONFIG_X86_64
473 needed_size = ALIGN(needed_size, MIN_KERNEL_ALIGN);
474 #endif
475
476 /* Report initial kernel position details. */
477 debug_putaddr(input_data);
478 debug_putaddr(input_len);
479 debug_putaddr(output);
480 debug_putaddr(output_len);
481 debug_putaddr(kernel_total_size);
482 debug_putaddr(needed_size);
483
484 #ifdef CONFIG_X86_64
485 /* Report address of 32-bit trampoline */
486 debug_putaddr(trampoline_32bit);
487 #endif
488
489 choose_random_location((unsigned long)input_data, input_len,
490 (unsigned long *)&output,
491 needed_size,
492 &virt_addr);
493
494 /* Validate memory location choices. */
495 if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
496 error("Destination physical address inappropriately aligned");
497 if (virt_addr & (MIN_KERNEL_ALIGN - 1))
498 error("Destination virtual address inappropriately aligned");
499 #ifdef CONFIG_X86_64
500 if (heap > 0x3fffffffffffUL)
501 error("Destination address too large");
502 if (virt_addr + needed_size > KERNEL_IMAGE_SIZE)
503 error("Destination virtual address is beyond the kernel mapping area");
504 #else
505 if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
506 error("Destination address too large");
507 #endif
508 #ifndef CONFIG_RELOCATABLE
509 if (virt_addr != LOAD_PHYSICAL_ADDR)
510 error("Destination virtual address changed when not relocatable");
511 #endif
512
513 debug_putstr("\nDecompressing Linux... ");
514
515 if (init_unaccepted_memory()) {
516 debug_putstr("Accepting memory... ");
517 accept_memory(__pa(output), needed_size);
518 }
519
520 entry_offset = decompress_kernel(output, virt_addr, error);
521
522 debug_putstr("done.\nBooting the kernel (entry_offset: 0x");
523 debug_puthex(entry_offset);
524 debug_putstr(").\n");
525
526 /* Disable exception handling before booting the kernel */
527 cleanup_exception_handling();
528
529 if (spurious_nmi_count) {
530 error_putstr("Spurious early NMIs ignored: ");
531 error_putdec(spurious_nmi_count);
532 error_putstr("\n");
533 }
534
535 return output + entry_offset;
536 }
537