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
18 #include "../string.h"
19 #include "../voffset.h"
20 #include <asm/bootparam_utils.h>
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.
29 /* Macros used by the included decompressor code below. */
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.
36 #define memzero(s, n) memset((s), 0, (n))
37 #define memmove memmove
39 /* Functions used by the included decompressor code below. */
40 void *memmove(void *dest, const void *src, size_t n);
43 * This is set up by the setup-routine at boot-time
45 struct boot_params *boot_params;
48 memptr free_mem_end_ptr;
52 static int lines, cols;
54 #ifdef CONFIG_KERNEL_GZIP
55 #include "../../../../lib/decompress_inflate.c"
58 #ifdef CONFIG_KERNEL_BZIP2
59 #include "../../../../lib/decompress_bunzip2.c"
62 #ifdef CONFIG_KERNEL_LZMA
63 #include "../../../../lib/decompress_unlzma.c"
66 #ifdef CONFIG_KERNEL_XZ
67 #include "../../../../lib/decompress_unxz.c"
70 #ifdef CONFIG_KERNEL_LZO
71 #include "../../../../lib/decompress_unlzo.c"
74 #ifdef CONFIG_KERNEL_LZ4
75 #include "../../../../lib/decompress_unlz4.c"
78 #ifdef CONFIG_KERNEL_ZSTD
79 #include "../../../../lib/decompress_unzstd.c"
82 * NOTE: When adding a new decompressor, please update the analysis in
86 static void scroll(void)
90 memmove(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
91 for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
97 #define TXR 0 /* Transmit register (WRITE) */
98 #define LSR 5 /* Line Status */
99 static void serial_putchar(int ch)
101 unsigned timeout = 0xffff;
103 while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
106 outb(ch, early_serial_base + TXR);
109 void __putstr(const char *s)
114 if (early_serial_base) {
118 serial_putchar('\r');
119 serial_putchar(*str++);
123 if (lines == 0 || cols == 0)
126 x = boot_params->screen_info.orig_x;
127 y = boot_params->screen_info.orig_y;
129 while ((c = *s++) != '\0') {
137 vidmem[(x + cols * y) * 2] = c;
148 boot_params->screen_info.orig_x = x;
149 boot_params->screen_info.orig_y = y;
151 pos = (x + cols * y) * 2; /* Update cursor position */
153 outb(0xff & (pos >> 9), vidport+1);
155 outb(0xff & (pos >> 1), vidport+1);
158 void __puthex(unsigned long value)
163 for (bits = sizeof(value) * 8 - 4; bits >= 0; bits -= 4) {
164 unsigned long digit = (value >> bits) & 0xf;
167 alpha[0] = '0' + digit;
169 alpha[0] = 'a' + (digit - 0xA);
175 #if CONFIG_X86_NEED_RELOCS
176 static void handle_relocations(void *output, unsigned long output_len,
177 unsigned long virt_addr)
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);
185 * Calculate the delta between where vmlinux was linked to load
186 * and where it was actually loaded.
188 delta = min_addr - LOAD_PHYSICAL_ADDR;
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.
197 map = delta - __START_KERNEL_map;
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.
204 if (IS_ENABLED(CONFIG_X86_64))
205 delta = virt_addr - LOAD_PHYSICAL_ADDR;
208 debug_putstr("No relocation needed... ");
211 debug_putstr("Performing relocations... ");
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.
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
230 * So we work backwards from the end of the decompressed image.
232 for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) {
233 long extended = *reloc;
236 ptr = (unsigned long)extended;
237 if (ptr < min_addr || ptr > max_addr)
238 error("32-bit relocation outside of kernel!\n");
240 *(uint32_t *)ptr += delta;
244 long extended = *reloc;
247 ptr = (unsigned long)extended;
248 if (ptr < min_addr || ptr > max_addr)
249 error("inverse 32-bit relocation outside of kernel!\n");
251 *(int32_t *)ptr -= delta;
253 for (reloc--; *reloc; reloc--) {
254 long extended = *reloc;
257 ptr = (unsigned long)extended;
258 if (ptr < min_addr || ptr > max_addr)
259 error("64-bit relocation outside of kernel!\n");
261 *(uint64_t *)ptr += delta;
266 static inline void handle_relocations(void *output, unsigned long output_len,
267 unsigned long virt_addr)
271 static void parse_elf(void *output)
275 Elf64_Phdr *phdrs, *phdr;
278 Elf32_Phdr *phdrs, *phdr;
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");
292 debug_putstr("Parsing ELF... ");
294 phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
296 error("Failed to allocate space for phdrs");
298 memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
300 for (i = 0; i < ehdr.e_phnum; i++) {
303 switch (phdr->p_type) {
306 if ((phdr->p_align % 0x200000) != 0)
307 error("Alignment of LOAD segment isn't multiple of 2MB");
309 #ifdef CONFIG_RELOCATABLE
311 dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
313 dest = (void *)(phdr->p_paddr);
315 memmove(dest, output + phdr->p_offset, phdr->p_filesz);
317 default: /* Ignore other PT_* */ break;
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
331 * |-----compressed kernel image------|
333 * 0 extract_offset +INIT_SIZE
334 * |-----------|---------------|-------------------------|--------|
336 * VO__text startup_32 of ZO VO__end ZO__end
338 * |-------uncompressed kernel image---------|
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)
347 const unsigned long kernel_total_size = VO__end - VO__text;
348 unsigned long virt_addr = LOAD_PHYSICAL_ADDR;
349 unsigned long needed_size;
351 /* Retain x86 boot parameters pointer passed from startup_32/64. */
354 /* Clear flags intended for solely in-kernel use. */
355 boot_params->hdr.loadflags &= ~KASLR_FLAG;
357 sanitize_boot_params(boot_params);
359 if (boot_params->screen_info.orig_video_mode == 7) {
360 vidmem = (char *) 0xb0000;
363 vidmem = (char *) 0xb8000;
367 lines = boot_params->screen_info.orig_video_lines;
368 cols = boot_params->screen_info.orig_video_cols;
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
377 boot_params->acpi_rsdp_addr = get_rsdp_addr();
379 debug_putstr("early console in extract_kernel\n");
381 free_mem_ptr = heap; /* Heap */
382 free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
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.
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.
395 needed_size = max(output_len, kernel_total_size);
397 needed_size = ALIGN(needed_size, MIN_KERNEL_ALIGN);
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);
409 /* Report address of 32-bit trampoline */
410 debug_putaddr(trampoline_32bit);
413 choose_random_location((unsigned long)input_data, input_len,
414 (unsigned long *)&output,
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");
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");
429 if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
430 error("Destination address too large");
432 #ifndef CONFIG_RELOCATABLE
433 if (virt_addr != LOAD_PHYSICAL_ADDR)
434 error("Destination virtual address changed when not relocatable");
437 debug_putstr("\nDecompressing Linux... ");
438 __decompress(input_data, input_len, NULL, NULL, output, output_len,
441 handle_relocations(output, output_len, virt_addr);
442 debug_putstr("done.\nBooting the kernel.\n");
444 /* Disable exception handling before booting the kernel */
445 cleanup_exception_handling();
450 void fortify_panic(const char *name)
452 error("detected buffer overflow");