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