1 // SPDX-License-Identifier: GPL-2.0
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.
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
17 #include "../string.h"
18 #include "../voffset.h"
19 #include <asm/bootparam_utils.h>
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.
28 /* Macros used by the included decompressor code below. */
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.
38 #define memzero(s, n) memset((s), 0, (n))
39 #define memmove memmove
41 /* Functions used by the included decompressor code below. */
42 void *memmove(void *dest, const void *src, size_t n);
45 * This is set up by the setup-routine at boot-time
47 struct boot_params *boot_params;
50 memptr free_mem_end_ptr;
54 static int lines, cols;
56 #ifdef CONFIG_KERNEL_GZIP
57 #include "../../../../lib/decompress_inflate.c"
60 #ifdef CONFIG_KERNEL_BZIP2
61 #include "../../../../lib/decompress_bunzip2.c"
64 #ifdef CONFIG_KERNEL_LZMA
65 #include "../../../../lib/decompress_unlzma.c"
68 #ifdef CONFIG_KERNEL_XZ
69 #include "../../../../lib/decompress_unxz.c"
72 #ifdef CONFIG_KERNEL_LZO
73 #include "../../../../lib/decompress_unlzo.c"
76 #ifdef CONFIG_KERNEL_LZ4
77 #include "../../../../lib/decompress_unlz4.c"
80 * NOTE: When adding a new decompressor, please update the analysis in
84 static void scroll(void)
88 memmove(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
89 for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
95 #define TXR 0 /* Transmit register (WRITE) */
96 #define LSR 5 /* Line Status */
97 static void serial_putchar(int ch)
99 unsigned timeout = 0xffff;
101 while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
104 outb(ch, early_serial_base + TXR);
107 void __putstr(const char *s)
112 if (early_serial_base) {
116 serial_putchar('\r');
117 serial_putchar(*str++);
121 if (lines == 0 || cols == 0)
124 x = boot_params->screen_info.orig_x;
125 y = boot_params->screen_info.orig_y;
127 while ((c = *s++) != '\0') {
135 vidmem[(x + cols * y) * 2] = c;
146 boot_params->screen_info.orig_x = x;
147 boot_params->screen_info.orig_y = y;
149 pos = (x + cols * y) * 2; /* Update cursor position */
151 outb(0xff & (pos >> 9), vidport+1);
153 outb(0xff & (pos >> 1), vidport+1);
156 void __puthex(unsigned long value)
161 for (bits = sizeof(value) * 8 - 4; bits >= 0; bits -= 4) {
162 unsigned long digit = (value >> bits) & 0xf;
165 alpha[0] = '0' + digit;
167 alpha[0] = 'a' + (digit - 0xA);
173 static bool l5_supported(void)
175 /* Check if leaf 7 is supported. */
176 if (native_cpuid_eax(0) < 7)
179 /* Check if la57 is supported. */
180 return native_cpuid_ecx(7) & (1 << (X86_FEATURE_LA57 & 31));
183 #if CONFIG_X86_NEED_RELOCS
184 static void handle_relocations(void *output, unsigned long output_len,
185 unsigned long virt_addr)
188 unsigned long delta, map, ptr;
189 unsigned long min_addr = (unsigned long)output;
190 unsigned long max_addr = min_addr + (VO___bss_start - VO__text);
193 * Calculate the delta between where vmlinux was linked to load
194 * and where it was actually loaded.
196 delta = min_addr - LOAD_PHYSICAL_ADDR;
199 * The kernel contains a table of relocation addresses. Those
200 * addresses have the final load address of the kernel in virtual
201 * memory. We are currently working in the self map. So we need to
202 * create an adjustment for kernel memory addresses to the self map.
203 * This will involve subtracting out the base address of the kernel.
205 map = delta - __START_KERNEL_map;
208 * 32-bit always performs relocations. 64-bit relocations are only
209 * needed if KASLR has chosen a different starting address offset
210 * from __START_KERNEL_map.
212 if (IS_ENABLED(CONFIG_X86_64))
213 delta = virt_addr - LOAD_PHYSICAL_ADDR;
216 debug_putstr("No relocation needed... ");
219 debug_putstr("Performing relocations... ");
222 * Process relocations: 32 bit relocations first then 64 bit after.
223 * Three sets of binary relocations are added to the end of the kernel
224 * before compression. Each relocation table entry is the kernel
225 * address of the location which needs to be updated stored as a
226 * 32-bit value which is sign extended to 64 bits.
231 * 0 - zero terminator for 64 bit relocations
232 * 64 bit relocation repeated
233 * 0 - zero terminator for inverse 32 bit relocations
234 * 32 bit inverse relocation repeated
235 * 0 - zero terminator for 32 bit relocations
236 * 32 bit relocation repeated
238 * So we work backwards from the end of the decompressed image.
240 for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) {
241 long extended = *reloc;
244 ptr = (unsigned long)extended;
245 if (ptr < min_addr || ptr > max_addr)
246 error("32-bit relocation outside of kernel!\n");
248 *(uint32_t *)ptr += delta;
252 long extended = *reloc;
255 ptr = (unsigned long)extended;
256 if (ptr < min_addr || ptr > max_addr)
257 error("inverse 32-bit relocation outside of kernel!\n");
259 *(int32_t *)ptr -= delta;
261 for (reloc--; *reloc; reloc--) {
262 long extended = *reloc;
265 ptr = (unsigned long)extended;
266 if (ptr < min_addr || ptr > max_addr)
267 error("64-bit relocation outside of kernel!\n");
269 *(uint64_t *)ptr += delta;
274 static inline void handle_relocations(void *output, unsigned long output_len,
275 unsigned long virt_addr)
279 static void parse_elf(void *output)
283 Elf64_Phdr *phdrs, *phdr;
286 Elf32_Phdr *phdrs, *phdr;
291 memcpy(&ehdr, output, sizeof(ehdr));
292 if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
293 ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
294 ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
295 ehdr.e_ident[EI_MAG3] != ELFMAG3) {
296 error("Kernel is not a valid ELF file");
300 debug_putstr("Parsing ELF... ");
302 phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
304 error("Failed to allocate space for phdrs");
306 memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
308 for (i = 0; i < ehdr.e_phnum; i++) {
311 switch (phdr->p_type) {
314 if ((phdr->p_align % 0x200000) != 0)
315 error("Alignment of LOAD segment isn't multiple of 2MB");
317 #ifdef CONFIG_RELOCATABLE
319 dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
321 dest = (void *)(phdr->p_paddr);
323 memmove(dest, output + phdr->p_offset, phdr->p_filesz);
325 default: /* Ignore other PT_* */ break;
333 * The compressed kernel image (ZO), has been moved so that its position
334 * is against the end of the buffer used to hold the uncompressed kernel
335 * image (VO) and the execution environment (.bss, .brk), which makes sure
336 * there is room to do the in-place decompression. (See header.S for the
339 * |-----compressed kernel image------|
341 * 0 extract_offset +INIT_SIZE
342 * |-----------|---------------|-------------------------|--------|
344 * VO__text startup_32 of ZO VO__end ZO__end
346 * |-------uncompressed kernel image---------|
349 asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
350 unsigned char *input_data,
351 unsigned long input_len,
352 unsigned char *output,
353 unsigned long output_len)
355 const unsigned long kernel_total_size = VO__end - VO__text;
356 unsigned long virt_addr = LOAD_PHYSICAL_ADDR;
358 /* Retain x86 boot parameters pointer passed from startup_32/64. */
361 /* Clear flags intended for solely in-kernel use. */
362 boot_params->hdr.loadflags &= ~KASLR_FLAG;
364 sanitize_boot_params(boot_params);
366 if (boot_params->screen_info.orig_video_mode == 7) {
367 vidmem = (char *) 0xb0000;
370 vidmem = (char *) 0xb8000;
374 lines = boot_params->screen_info.orig_video_lines;
375 cols = boot_params->screen_info.orig_video_cols;
378 debug_putstr("early console in extract_kernel\n");
380 if (IS_ENABLED(CONFIG_X86_5LEVEL) && !l5_supported()) {
381 error("This linux kernel as configured requires 5-level paging\n"
382 "This CPU does not support the required 'cr4.la57' feature\n"
383 "Unable to boot - please use a kernel appropriate for your CPU\n");
386 free_mem_ptr = heap; /* Heap */
387 free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
389 /* Report initial kernel position details. */
390 debug_putaddr(input_data);
391 debug_putaddr(input_len);
392 debug_putaddr(output);
393 debug_putaddr(output_len);
394 debug_putaddr(kernel_total_size);
397 * The memory hole needed for the kernel is the larger of either
398 * the entire decompressed kernel plus relocation table, or the
399 * entire decompressed kernel plus .bss and .brk sections.
401 choose_random_location((unsigned long)input_data, input_len,
402 (unsigned long *)&output,
403 max(output_len, kernel_total_size),
406 /* Validate memory location choices. */
407 if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
408 error("Destination physical address inappropriately aligned");
409 if (virt_addr & (MIN_KERNEL_ALIGN - 1))
410 error("Destination virtual address inappropriately aligned");
412 if (heap > 0x3fffffffffffUL)
413 error("Destination address too large");
414 if (virt_addr + max(output_len, kernel_total_size) > KERNEL_IMAGE_SIZE)
415 error("Destination virtual address is beyond the kernel mapping area");
417 if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
418 error("Destination address too large");
420 #ifndef CONFIG_RELOCATABLE
421 if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
422 error("Destination address does not match LOAD_PHYSICAL_ADDR");
423 if (virt_addr != LOAD_PHYSICAL_ADDR)
424 error("Destination virtual address changed when not relocatable");
427 debug_putstr("\nDecompressing Linux... ");
428 __decompress(input_data, input_len, NULL, NULL, output, output_len,
431 handle_relocations(output, output_len, virt_addr);
432 debug_putstr("done.\nBooting the kernel.\n");
436 void fortify_panic(const char *name)
438 error("detected buffer overflow");