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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
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
31/*
32 * Use normal definitions of mem*() from string.c. There are already
33 * included header files which expect a definition of memset() and by
34 * the time we define memset macro, it is too late.
35 */
36#undef memcpy
37#undef memset
38#define memzero(s, n) memset((s), 0, (n))
39#define memmove memmove
40
41/* Functions used by the included decompressor code below. */
42void *memmove(void *dest, const void *src, size_t n);
43
44/*
45 * This is set up by the setup-routine at boot-time
46 */
47struct boot_params *boot_params;
48
49memptr free_mem_ptr;
50memptr free_mem_end_ptr;
51
52static char *vidmem;
53static int vidport;
54static int lines, cols;
55
56#ifdef CONFIG_KERNEL_GZIP
57#include "../../../../lib/decompress_inflate.c"
58#endif
59
60#ifdef CONFIG_KERNEL_BZIP2
61#include "../../../../lib/decompress_bunzip2.c"
62#endif
63
64#ifdef CONFIG_KERNEL_LZMA
65#include "../../../../lib/decompress_unlzma.c"
66#endif
67
68#ifdef CONFIG_KERNEL_XZ
69#include "../../../../lib/decompress_unxz.c"
70#endif
71
72#ifdef CONFIG_KERNEL_LZO
73#include "../../../../lib/decompress_unlzo.c"
74#endif
75
76#ifdef CONFIG_KERNEL_LZ4
77#include "../../../../lib/decompress_unlz4.c"
78#endif
79/*
80 * NOTE: When adding a new decompressor, please update the analysis in
81 * ../header.S.
82 */
83
84static void scroll(void)
85{
86 int i;
87
88 memmove(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
89 for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
90 vidmem[i] = ' ';
91}
92
93#define XMTRDY 0x20
94
95#define TXR 0 /* Transmit register (WRITE) */
96#define LSR 5 /* Line Status */
97static void serial_putchar(int ch)
98{
99 unsigned timeout = 0xffff;
100
101 while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
102 cpu_relax();
103
104 outb(ch, early_serial_base + TXR);
105}
106
107void __putstr(const char *s)
108{
109 int x, y, pos;
110 char c;
111
112 if (early_serial_base) {
113 const char *str = s;
114 while (*str) {
115 if (*str == '\n')
116 serial_putchar('\r');
117 serial_putchar(*str++);
118 }
119 }
120
121 if (lines == 0 || cols == 0)
122 return;
123
124 x = boot_params->screen_info.orig_x;
125 y = boot_params->screen_info.orig_y;
126
127 while ((c = *s++) != '\0') {
128 if (c == '\n') {
129 x = 0;
130 if (++y >= lines) {
131 scroll();
132 y--;
133 }
134 } else {
135 vidmem[(x + cols * y) * 2] = c;
136 if (++x >= cols) {
137 x = 0;
138 if (++y >= lines) {
139 scroll();
140 y--;
141 }
142 }
143 }
144 }
145
146 boot_params->screen_info.orig_x = x;
147 boot_params->screen_info.orig_y = y;
148
149 pos = (x + cols * y) * 2; /* Update cursor position */
150 outb(14, vidport);
151 outb(0xff & (pos >> 9), vidport+1);
152 outb(15, vidport);
153 outb(0xff & (pos >> 1), vidport+1);
154}
155
156void __puthex(unsigned long value)
157{
158 char alpha[2] = "0";
159 int bits;
160
161 for (bits = sizeof(value) * 8 - 4; bits >= 0; bits -= 4) {
162 unsigned long digit = (value >> bits) & 0xf;
163
164 if (digit < 0xA)
165 alpha[0] = '0' + digit;
166 else
167 alpha[0] = 'a' + (digit - 0xA);
168
169 __putstr(alpha);
170 }
171}
172
173#if CONFIG_X86_NEED_RELOCS
174static void handle_relocations(void *output, unsigned long output_len,
175 unsigned long virt_addr)
176{
177 int *reloc;
178 unsigned long delta, map, ptr;
179 unsigned long min_addr = (unsigned long)output;
180 unsigned long max_addr = min_addr + (VO___bss_start - VO__text);
181
182 /*
183 * Calculate the delta between where vmlinux was linked to load
184 * and where it was actually loaded.
185 */
186 delta = min_addr - LOAD_PHYSICAL_ADDR;
187
188 /*
189 * The kernel contains a table of relocation addresses. Those
190 * addresses have the final load address of the kernel in virtual
191 * memory. We are currently working in the self map. So we need to
192 * create an adjustment for kernel memory addresses to the self map.
193 * This will involve subtracting out the base address of the kernel.
194 */
195 map = delta - __START_KERNEL_map;
196
197 /*
198 * 32-bit always performs relocations. 64-bit relocations are only
199 * needed if KASLR has chosen a different starting address offset
200 * from __START_KERNEL_map.
201 */
202 if (IS_ENABLED(CONFIG_X86_64))
203 delta = virt_addr - LOAD_PHYSICAL_ADDR;
204
205 if (!delta) {
206 debug_putstr("No relocation needed... ");
207 return;
208 }
209 debug_putstr("Performing relocations... ");
210
211 /*
212 * Process relocations: 32 bit relocations first then 64 bit after.
213 * Three sets of binary relocations are added to the end of the kernel
214 * before compression. Each relocation table entry is the kernel
215 * address of the location which needs to be updated stored as a
216 * 32-bit value which is sign extended to 64 bits.
217 *
218 * Format is:
219 *
220 * kernel bits...
221 * 0 - zero terminator for 64 bit relocations
222 * 64 bit relocation repeated
223 * 0 - zero terminator for inverse 32 bit relocations
224 * 32 bit inverse relocation repeated
225 * 0 - zero terminator for 32 bit relocations
226 * 32 bit relocation repeated
227 *
228 * So we work backwards from the end of the decompressed image.
229 */
230 for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) {
231 long extended = *reloc;
232 extended += map;
233
234 ptr = (unsigned long)extended;
235 if (ptr < min_addr || ptr > max_addr)
236 error("32-bit relocation outside of kernel!\n");
237
238 *(uint32_t *)ptr += delta;
239 }
240#ifdef CONFIG_X86_64
241 while (*--reloc) {
242 long extended = *reloc;
243 extended += map;
244
245 ptr = (unsigned long)extended;
246 if (ptr < min_addr || ptr > max_addr)
247 error("inverse 32-bit relocation outside of kernel!\n");
248
249 *(int32_t *)ptr -= delta;
250 }
251 for (reloc--; *reloc; reloc--) {
252 long extended = *reloc;
253 extended += map;
254
255 ptr = (unsigned long)extended;
256 if (ptr < min_addr || ptr > max_addr)
257 error("64-bit relocation outside of kernel!\n");
258
259 *(uint64_t *)ptr += delta;
260 }
261#endif
262}
263#else
264static inline void handle_relocations(void *output, unsigned long output_len,
265 unsigned long virt_addr)
266{ }
267#endif
268
269static void parse_elf(void *output)
270{
271#ifdef CONFIG_X86_64
272 Elf64_Ehdr ehdr;
273 Elf64_Phdr *phdrs, *phdr;
274#else
275 Elf32_Ehdr ehdr;
276 Elf32_Phdr *phdrs, *phdr;
277#endif
278 void *dest;
279 int i;
280
281 memcpy(&ehdr, output, sizeof(ehdr));
282 if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
283 ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
284 ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
285 ehdr.e_ident[EI_MAG3] != ELFMAG3) {
286 error("Kernel is not a valid ELF file");
287 return;
288 }
289
290 debug_putstr("Parsing ELF... ");
291
292 phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
293 if (!phdrs)
294 error("Failed to allocate space for phdrs");
295
296 memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
297
298 for (i = 0; i < ehdr.e_phnum; i++) {
299 phdr = &phdrs[i];
300
301 switch (phdr->p_type) {
302 case PT_LOAD:
303#ifdef CONFIG_X86_64
304 if ((phdr->p_align % 0x200000) != 0)
305 error("Alignment of LOAD segment isn't multiple of 2MB");
306#endif
307#ifdef CONFIG_RELOCATABLE
308 dest = output;
309 dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
310#else
311 dest = (void *)(phdr->p_paddr);
312#endif
313 memmove(dest, output + phdr->p_offset, phdr->p_filesz);
314 break;
315 default: /* Ignore other PT_* */ break;
316 }
317 }
318
319 free(phdrs);
320}
321
322/*
323 * The compressed kernel image (ZO), has been moved so that its position
324 * is against the end of the buffer used to hold the uncompressed kernel
325 * image (VO) and the execution environment (.bss, .brk), which makes sure
326 * there is room to do the in-place decompression. (See header.S for the
327 * calculations.)
328 *
329 * |-----compressed kernel image------|
330 * V V
331 * 0 extract_offset +INIT_SIZE
332 * |-----------|---------------|-------------------------|--------|
333 * | | | |
334 * VO__text startup_32 of ZO VO__end ZO__end
335 * ^ ^
336 * |-------uncompressed kernel image---------|
337 *
338 */
339asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
340 unsigned char *input_data,
341 unsigned long input_len,
342 unsigned char *output,
343 unsigned long output_len)
344{
345 const unsigned long kernel_total_size = VO__end - VO__text;
346 unsigned long virt_addr = LOAD_PHYSICAL_ADDR;
347
348 /* Retain x86 boot parameters pointer passed from startup_32/64. */
349 boot_params = rmode;
350
351 /* Clear flags intended for solely in-kernel use. */
352 boot_params->hdr.loadflags &= ~KASLR_FLAG;
353
354 /* Save RSDP address for later use. */
355 boot_params->acpi_rsdp_addr = get_rsdp_addr();
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 debug_putstr("early console in extract_kernel\n");
372
373 free_mem_ptr = heap; /* Heap */
374 free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
375
376 /* Report initial kernel position details. */
377 debug_putaddr(input_data);
378 debug_putaddr(input_len);
379 debug_putaddr(output);
380 debug_putaddr(output_len);
381 debug_putaddr(kernel_total_size);
382
383#ifdef CONFIG_X86_64
384 /* Report address of 32-bit trampoline */
385 debug_putaddr(trampoline_32bit);
386#endif
387
388 /*
389 * The memory hole needed for the kernel is the larger of either
390 * the entire decompressed kernel plus relocation table, or the
391 * entire decompressed kernel plus .bss and .brk sections.
392 */
393 choose_random_location((unsigned long)input_data, input_len,
394 (unsigned long *)&output,
395 max(output_len, kernel_total_size),
396 &virt_addr);
397
398 /* Validate memory location choices. */
399 if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
400 error("Destination physical address inappropriately aligned");
401 if (virt_addr & (MIN_KERNEL_ALIGN - 1))
402 error("Destination virtual address inappropriately aligned");
403#ifdef CONFIG_X86_64
404 if (heap > 0x3fffffffffffUL)
405 error("Destination address too large");
406 if (virt_addr + max(output_len, kernel_total_size) > KERNEL_IMAGE_SIZE)
407 error("Destination virtual address is beyond the kernel mapping area");
408#else
409 if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
410 error("Destination address too large");
411#endif
412#ifndef CONFIG_RELOCATABLE
413 if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
414 error("Destination address does not match LOAD_PHYSICAL_ADDR");
415 if (virt_addr != LOAD_PHYSICAL_ADDR)
416 error("Destination virtual address changed when not relocatable");
417#endif
418
419 debug_putstr("\nDecompressing Linux... ");
420 __decompress(input_data, input_len, NULL, NULL, output, output_len,
421 NULL, error);
422 parse_elf(output);
423 handle_relocations(output, output_len, virt_addr);
424 debug_putstr("done.\nBooting the kernel.\n");
425 return output;
426}
427
428void fortify_panic(const char *name)
429{
430 error("detected buffer overflow");
431}
432

Warning: That file was not part of the compilation database. It may have many parsing errors.