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 #include <asm/bootparam_utils.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 /* Define an externally visible malloc()/free(). */
31 #define MALLOC_VISIBLE
32 #include <linux/decompress/mm.h>
33
34 /*
35 * Provide definitions of memzero and memmove as some of the decompressors will
36 * try to define their own functions if these are not defined as macros.
37 */
38 #define memzero(s, n) memset((s), 0, (n))
39 #ifndef memmove
40 #define memmove memmove
41 /* Functions used by the included decompressor code below. */
42 void *memmove(void *dest, const void *src, size_t n);
43 #endif
44
45 /*
46 * This is set up by the setup-routine at boot-time
47 */
48 struct boot_params *boot_params_ptr;
49
50 struct port_io_ops pio_ops;
51
52 memptr free_mem_ptr;
53 memptr free_mem_end_ptr;
54 int spurious_nmi_count;
55
56 static char *vidmem;
57 static int vidport;
58
59 /* These might be accessed before .bss is cleared, so use .data instead. */
60 static int lines __section(".data");
61 static int cols __section(".data");
62
63 #ifdef CONFIG_KERNEL_GZIP
64 #include "../../../../lib/decompress_inflate.c"
65 #endif
66
67 #ifdef CONFIG_KERNEL_BZIP2
68 #include "../../../../lib/decompress_bunzip2.c"
69 #endif
70
71 #ifdef CONFIG_KERNEL_LZMA
72 #include "../../../../lib/decompress_unlzma.c"
73 #endif
74
75 #ifdef CONFIG_KERNEL_XZ
76 #include "../../../../lib/decompress_unxz.c"
77 #endif
78
79 #ifdef CONFIG_KERNEL_LZO
80 #include "../../../../lib/decompress_unlzo.c"
81 #endif
82
83 #ifdef CONFIG_KERNEL_LZ4
84 #include "../../../../lib/decompress_unlz4.c"
85 #endif
86
87 #ifdef CONFIG_KERNEL_ZSTD
88 #include "../../../../lib/decompress_unzstd.c"
89 #endif
90 /*
91 * NOTE: When adding a new decompressor, please update the analysis in
92 * ../header.S.
93 */
94
scroll(void)95 static void scroll(void)
96 {
97 int i;
98
99 memmove(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
100 for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
101 vidmem[i] = ' ';
102 }
103
104 #define XMTRDY 0x20
105
106 #define TXR 0 /* Transmit register (WRITE) */
107 #define LSR 5 /* Line Status */
serial_putchar(int ch)108 static void serial_putchar(int ch)
109 {
110 unsigned timeout = 0xffff;
111
112 while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
113 cpu_relax();
114
115 outb(ch, early_serial_base + TXR);
116 }
117
__putstr(const char * s)118 void __putstr(const char *s)
119 {
120 int x, y, pos;
121 char c;
122
123 if (early_serial_base) {
124 const char *str = s;
125 while (*str) {
126 if (*str == '\n')
127 serial_putchar('\r');
128 serial_putchar(*str++);
129 }
130 }
131
132 if (lines == 0 || cols == 0)
133 return;
134
135 x = boot_params_ptr->screen_info.orig_x;
136 y = boot_params_ptr->screen_info.orig_y;
137
138 while ((c = *s++) != '\0') {
139 if (c == '\n') {
140 x = 0;
141 if (++y >= lines) {
142 scroll();
143 y--;
144 }
145 } else {
146 vidmem[(x + cols * y) * 2] = c;
147 if (++x >= cols) {
148 x = 0;
149 if (++y >= lines) {
150 scroll();
151 y--;
152 }
153 }
154 }
155 }
156
157 boot_params_ptr->screen_info.orig_x = x;
158 boot_params_ptr->screen_info.orig_y = y;
159
160 pos = (x + cols * y) * 2; /* Update cursor position */
161 outb(14, vidport);
162 outb(0xff & (pos >> 9), vidport+1);
163 outb(15, vidport);
164 outb(0xff & (pos >> 1), vidport+1);
165 }
166
__putnum(unsigned long value,unsigned int base,int mindig)167 static noinline void __putnum(unsigned long value, unsigned int base,
168 int mindig)
169 {
170 char buf[8*sizeof(value)+1];
171 char *p;
172
173 p = buf + sizeof(buf);
174 *--p = '\0';
175
176 while (mindig-- > 0 || value) {
177 unsigned char digit = value % base;
178 digit += (digit >= 10) ? ('a'-10) : '0';
179 *--p = digit;
180
181 value /= base;
182 }
183
184 __putstr(p);
185 }
186
__puthex(unsigned long value)187 void __puthex(unsigned long value)
188 {
189 __putnum(value, 16, sizeof(value)*2);
190 }
191
__putdec(unsigned long value)192 void __putdec(unsigned long value)
193 {
194 __putnum(value, 10, 1);
195 }
196
197 #ifdef CONFIG_X86_NEED_RELOCS
handle_relocations(void * output,unsigned long output_len,unsigned long virt_addr)198 static void handle_relocations(void *output, unsigned long output_len,
199 unsigned long virt_addr)
200 {
201 int *reloc;
202 unsigned long delta, map, ptr;
203 unsigned long min_addr = (unsigned long)output;
204 unsigned long max_addr = min_addr + (VO___bss_start - VO__text);
205
206 /*
207 * Calculate the delta between where vmlinux was linked to load
208 * and where it was actually loaded.
209 */
210 delta = min_addr - LOAD_PHYSICAL_ADDR;
211
212 /*
213 * The kernel contains a table of relocation addresses. Those
214 * addresses have the final load address of the kernel in virtual
215 * memory. We are currently working in the self map. So we need to
216 * create an adjustment for kernel memory addresses to the self map.
217 * This will involve subtracting out the base address of the kernel.
218 */
219 map = delta - __START_KERNEL_map;
220
221 /*
222 * 32-bit always performs relocations. 64-bit relocations are only
223 * needed if KASLR has chosen a different starting address offset
224 * from __START_KERNEL_map.
225 */
226 if (IS_ENABLED(CONFIG_X86_64))
227 delta = virt_addr - LOAD_PHYSICAL_ADDR;
228
229 if (!delta) {
230 debug_putstr("No relocation needed... ");
231 return;
232 }
233 debug_putstr("Performing relocations... ");
234
235 /*
236 * Process relocations: 32 bit relocations first then 64 bit after.
237 * Two sets of binary relocations are added to the end of the kernel
238 * before compression. Each relocation table entry is the kernel
239 * address of the location which needs to be updated stored as a
240 * 32-bit value which is sign extended to 64 bits.
241 *
242 * Format is:
243 *
244 * kernel bits...
245 * 0 - zero terminator for 64 bit relocations
246 * 64 bit relocation repeated
247 * 0 - zero terminator for 32 bit relocations
248 * 32 bit relocation repeated
249 *
250 * So we work backwards from the end of the decompressed image.
251 */
252 for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) {
253 long extended = *reloc;
254 extended += map;
255
256 ptr = (unsigned long)extended;
257 if (ptr < min_addr || ptr > max_addr)
258 error("32-bit relocation outside of kernel!\n");
259
260 *(uint32_t *)ptr += delta;
261 }
262 #ifdef CONFIG_X86_64
263 for (reloc--; *reloc; reloc--) {
264 long extended = *reloc;
265 extended += map;
266
267 ptr = (unsigned long)extended;
268 if (ptr < min_addr || ptr > max_addr)
269 error("64-bit relocation outside of kernel!\n");
270
271 *(uint64_t *)ptr += delta;
272 }
273 #endif
274 }
275 #else
handle_relocations(void * output,unsigned long output_len,unsigned long virt_addr)276 static inline void handle_relocations(void *output, unsigned long output_len,
277 unsigned long virt_addr)
278 { }
279 #endif
280
parse_elf(void * output)281 static size_t parse_elf(void *output)
282 {
283 #ifdef CONFIG_X86_64
284 Elf64_Ehdr ehdr;
285 Elf64_Phdr *phdrs, *phdr;
286 #else
287 Elf32_Ehdr ehdr;
288 Elf32_Phdr *phdrs, *phdr;
289 #endif
290 void *dest;
291 int i;
292
293 memcpy(&ehdr, output, sizeof(ehdr));
294 if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
295 ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
296 ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
297 ehdr.e_ident[EI_MAG3] != ELFMAG3)
298 error("Kernel is not a valid ELF file");
299
300 debug_putstr("Parsing ELF... ");
301
302 phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
303 if (!phdrs)
304 error("Failed to allocate space for phdrs");
305
306 memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
307
308 for (i = 0; i < ehdr.e_phnum; i++) {
309 phdr = &phdrs[i];
310
311 switch (phdr->p_type) {
312 case PT_LOAD:
313 #ifdef CONFIG_X86_64
314 if ((phdr->p_align % 0x200000) != 0)
315 error("Alignment of LOAD segment isn't multiple of 2MB");
316 #endif
317 #ifdef CONFIG_RELOCATABLE
318 dest = output;
319 dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
320 #else
321 dest = (void *)(phdr->p_paddr);
322 #endif
323 memmove(dest, output + phdr->p_offset, phdr->p_filesz);
324 break;
325 default: /* Ignore other PT_* */ break;
326 }
327 }
328
329 free(phdrs);
330
331 return ehdr.e_entry - LOAD_PHYSICAL_ADDR;
332 }
333
334 const unsigned long kernel_text_size = VO___start_rodata - VO__text;
335 const unsigned long kernel_total_size = VO__end - VO__text;
336
337 static u8 boot_heap[BOOT_HEAP_SIZE] __aligned(4);
338
339 extern unsigned char input_data[];
340 extern unsigned int input_len, output_len;
341
decompress_kernel(unsigned char * outbuf,unsigned long virt_addr,void (* error)(char * x))342 unsigned long decompress_kernel(unsigned char *outbuf, unsigned long virt_addr,
343 void (*error)(char *x))
344 {
345 unsigned long entry;
346
347 if (!free_mem_ptr) {
348 free_mem_ptr = (unsigned long)boot_heap;
349 free_mem_end_ptr = (unsigned long)boot_heap + sizeof(boot_heap);
350 }
351
352 if (__decompress(input_data, input_len, NULL, NULL, outbuf, output_len,
353 NULL, error) < 0)
354 return ULONG_MAX;
355
356 entry = parse_elf(outbuf);
357 handle_relocations(outbuf, output_len, virt_addr);
358
359 return entry;
360 }
361
362 /*
363 * Set the memory encryption xloadflag based on the mem_encrypt= command line
364 * parameter, if provided.
365 */
parse_mem_encrypt(struct setup_header * hdr)366 static void parse_mem_encrypt(struct setup_header *hdr)
367 {
368 int on = cmdline_find_option_bool("mem_encrypt=on");
369 int off = cmdline_find_option_bool("mem_encrypt=off");
370
371 if (on > off)
372 hdr->xloadflags |= XLF_MEM_ENCRYPTION;
373 }
374
early_sev_detect(void)375 static void early_sev_detect(void)
376 {
377 /*
378 * Accessing video memory causes guest termination because
379 * the boot stage2 #VC handler of SEV-ES/SNP guests does not
380 * support MMIO handling and kexec -c adds screen_info to the
381 * boot parameters passed to the kexec kernel, which causes
382 * console output to be dumped to both video and serial.
383 */
384 if (sev_status & MSR_AMD64_SEV_ES_ENABLED)
385 lines = cols = 0;
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 */
extract_kernel(void * rmode,unsigned char * output)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 early_sev_detect();
444
445 console_init();
446
447 /*
448 * Save RSDP address for later use. Have this after console_init()
449 * so that early debugging output from the RSDP parsing code can be
450 * collected.
451 */
452 boot_params_ptr->acpi_rsdp_addr = get_rsdp_addr();
453
454 debug_putstr("early console in extract_kernel\n");
455
456 free_mem_ptr = heap; /* Heap */
457 free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
458
459 /*
460 * The memory hole needed for the kernel is the larger of either
461 * the entire decompressed kernel plus relocation table, or the
462 * entire decompressed kernel plus .bss and .brk sections.
463 *
464 * On X86_64, the memory is mapped with PMD pages. Round the
465 * size up so that the full extent of PMD pages mapped is
466 * included in the check against the valid memory table
467 * entries. This ensures the full mapped area is usable RAM
468 * and doesn't include any reserved areas.
469 */
470 needed_size = max_t(unsigned long, output_len, kernel_total_size);
471 #ifdef CONFIG_X86_64
472 needed_size = ALIGN(needed_size, MIN_KERNEL_ALIGN);
473 #endif
474
475 /* Report initial kernel position details. */
476 debug_putaddr(input_data);
477 debug_putaddr(input_len);
478 debug_putaddr(output);
479 debug_putaddr(output_len);
480 debug_putaddr(kernel_total_size);
481 debug_putaddr(needed_size);
482
483 #ifdef CONFIG_X86_64
484 /* Report address of 32-bit trampoline */
485 debug_putaddr(trampoline_32bit);
486 #endif
487
488 choose_random_location((unsigned long)input_data, input_len,
489 (unsigned long *)&output,
490 needed_size,
491 &virt_addr);
492
493 /* Validate memory location choices. */
494 if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
495 error("Destination physical address inappropriately aligned");
496 if (virt_addr & (MIN_KERNEL_ALIGN - 1))
497 error("Destination virtual address inappropriately aligned");
498 #ifdef CONFIG_X86_64
499 if (heap > 0x3fffffffffffUL)
500 error("Destination address too large");
501 if (virt_addr + needed_size > KERNEL_IMAGE_SIZE)
502 error("Destination virtual address is beyond the kernel mapping area");
503 #else
504 if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
505 error("Destination address too large");
506 #endif
507 #ifndef CONFIG_RELOCATABLE
508 if (virt_addr != LOAD_PHYSICAL_ADDR)
509 error("Destination virtual address changed when not relocatable");
510 #endif
511
512 debug_putstr("\nDecompressing Linux... ");
513
514 if (init_unaccepted_memory()) {
515 debug_putstr("Accepting memory... ");
516 accept_memory(__pa(output), needed_size);
517 }
518
519 entry_offset = decompress_kernel(output, virt_addr, error);
520
521 debug_putstr("done.\nBooting the kernel (entry_offset: 0x");
522 debug_puthex(entry_offset);
523 debug_putstr(").\n");
524
525 /* Disable exception handling before booting the kernel */
526 cleanup_exception_handling();
527
528 if (spurious_nmi_count) {
529 error_putstr("Spurious early NMIs ignored: ");
530 error_putdec(spurious_nmi_count);
531 error_putstr("\n");
532 }
533
534 return output + entry_offset;
535 }
536