4 * This is a collection of several routines used to extract the kernel
5 * which includes KASLR relocation, decompression, ELF parsing, and
6 * relocation processing. Additionally included are the screen and serial
7 * output functions and related debugging support functions.
9 * malloc by Hannu Savolainen 1993 and Matthias Urlichs 1994
10 * puts by Nick Holloway 1993, better puts by Martin Mares 1995
11 * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
15 #include "../string.h"
19 * This code is compiled with -fPIC and it is relocated dynamically at
20 * run time, but no relocation processing is performed. This means that
21 * it is not safe to place pointers in static structures.
24 /* Macros used by the included decompressor code below. */
28 * Use normal definitions of mem*() from string.c. There are already
29 * included header files which expect a definition of memset() and by
30 * the time we define memset macro, it is too late.
34 #define memzero(s, n) memset((s), 0, (n))
35 #define memmove memmove
37 /* Functions used by the included decompressor code below. */
38 static void error(char *m);
39 void *memmove(void *dest, const void *src, size_t n);
42 * This is set up by the setup-routine at boot-time
44 struct boot_params *boot_params;
47 memptr free_mem_end_ptr;
51 static int lines, cols;
53 #ifdef CONFIG_KERNEL_GZIP
54 #include "../../../../lib/decompress_inflate.c"
57 #ifdef CONFIG_KERNEL_BZIP2
58 #include "../../../../lib/decompress_bunzip2.c"
61 #ifdef CONFIG_KERNEL_LZMA
62 #include "../../../../lib/decompress_unlzma.c"
65 #ifdef CONFIG_KERNEL_XZ
66 #include "../../../../lib/decompress_unxz.c"
69 #ifdef CONFIG_KERNEL_LZO
70 #include "../../../../lib/decompress_unlzo.c"
73 #ifdef CONFIG_KERNEL_LZ4
74 #include "../../../../lib/decompress_unlz4.c"
77 * NOTE: When adding a new decompressor, please update the analysis in
81 static void scroll(void)
85 memmove(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
86 for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
92 #define TXR 0 /* Transmit register (WRITE) */
93 #define LSR 5 /* Line Status */
94 static void serial_putchar(int ch)
96 unsigned timeout = 0xffff;
98 while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
101 outb(ch, early_serial_base + TXR);
104 void __putstr(const char *s)
109 if (early_serial_base) {
113 serial_putchar('\r');
114 serial_putchar(*str++);
118 if (boot_params->screen_info.orig_video_mode == 0 &&
119 lines == 0 && cols == 0)
122 x = boot_params->screen_info.orig_x;
123 y = boot_params->screen_info.orig_y;
125 while ((c = *s++) != '\0') {
133 vidmem[(x + cols * y) * 2] = c;
144 boot_params->screen_info.orig_x = x;
145 boot_params->screen_info.orig_y = y;
147 pos = (x + cols * y) * 2; /* Update cursor position */
149 outb(0xff & (pos >> 9), vidport+1);
151 outb(0xff & (pos >> 1), vidport+1);
154 void __puthex(unsigned long value)
159 for (bits = sizeof(value) * 8 - 4; bits >= 0; bits -= 4) {
160 unsigned long digit = (value >> bits) & 0xf;
163 alpha[0] = '0' + digit;
165 alpha[0] = 'a' + (digit - 0xA);
173 error_putstr("\n\n");
175 error_putstr("\n\n");
178 static void error(char *m)
181 error_putstr(" -- System halted");
187 #if CONFIG_X86_NEED_RELOCS
188 static void handle_relocations(void *output, unsigned long output_len)
191 unsigned long delta, map, ptr;
192 unsigned long min_addr = (unsigned long)output;
193 unsigned long max_addr = min_addr + output_len;
196 * Calculate the delta between where vmlinux was linked to load
197 * and where it was actually loaded.
199 delta = min_addr - LOAD_PHYSICAL_ADDR;
201 debug_putstr("No relocation needed... ");
204 debug_putstr("Performing relocations... ");
207 * The kernel contains a table of relocation addresses. Those
208 * addresses have the final load address of the kernel in virtual
209 * memory. We are currently working in the self map. So we need to
210 * create an adjustment for kernel memory addresses to the self map.
211 * This will involve subtracting out the base address of the kernel.
213 map = delta - __START_KERNEL_map;
216 * Process relocations: 32 bit relocations first then 64 bit after.
217 * Three sets of binary relocations are added to the end of the kernel
218 * before compression. Each relocation table entry is the kernel
219 * address of the location which needs to be updated stored as a
220 * 32-bit value which is sign extended to 64 bits.
225 * 0 - zero terminator for 64 bit relocations
226 * 64 bit relocation repeated
227 * 0 - zero terminator for inverse 32 bit relocations
228 * 32 bit inverse relocation repeated
229 * 0 - zero terminator for 32 bit relocations
230 * 32 bit relocation repeated
232 * So we work backwards from the end of the decompressed image.
234 for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) {
235 long extended = *reloc;
238 ptr = (unsigned long)extended;
239 if (ptr < min_addr || ptr > max_addr)
240 error("32-bit relocation outside of kernel!\n");
242 *(uint32_t *)ptr += delta;
246 long extended = *reloc;
249 ptr = (unsigned long)extended;
250 if (ptr < min_addr || ptr > max_addr)
251 error("inverse 32-bit relocation outside of kernel!\n");
253 *(int32_t *)ptr -= delta;
255 for (reloc--; *reloc; reloc--) {
256 long extended = *reloc;
259 ptr = (unsigned long)extended;
260 if (ptr < min_addr || ptr > max_addr)
261 error("64-bit relocation outside of kernel!\n");
263 *(uint64_t *)ptr += delta;
268 static inline void handle_relocations(void *output, unsigned long output_len)
272 static void parse_elf(void *output)
276 Elf64_Phdr *phdrs, *phdr;
279 Elf32_Phdr *phdrs, *phdr;
284 memcpy(&ehdr, output, sizeof(ehdr));
285 if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
286 ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
287 ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
288 ehdr.e_ident[EI_MAG3] != ELFMAG3) {
289 error("Kernel is not a valid ELF file");
293 debug_putstr("Parsing ELF... ");
295 phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
297 error("Failed to allocate space for phdrs");
299 memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
301 for (i = 0; i < ehdr.e_phnum; i++) {
304 switch (phdr->p_type) {
306 #ifdef CONFIG_RELOCATABLE
308 dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
310 dest = (void *)(phdr->p_paddr);
312 memmove(dest, output + phdr->p_offset, phdr->p_filesz);
314 default: /* Ignore other PT_* */ break;
322 * The compressed kernel image (ZO), has been moved so that its position
323 * is against the end of the buffer used to hold the uncompressed kernel
324 * image (VO) and the execution environment (.bss, .brk), which makes sure
325 * there is room to do the in-place decompression. (See header.S for the
328 * |-----compressed kernel image------|
330 * 0 extract_offset +INIT_SIZE
331 * |-----------|---------------|-------------------------|--------|
333 * VO__text startup_32 of ZO VO__end ZO__end
335 * |-------uncompressed kernel image---------|
338 asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
339 unsigned char *input_data,
340 unsigned long input_len,
341 unsigned char *output,
342 unsigned long output_len,
343 unsigned long run_size)
345 unsigned char *output_orig = output;
347 /* Retain x86 boot parameters pointer passed from startup_32/64. */
350 /* Clear flags intended for solely in-kernel use. */
351 boot_params->hdr.loadflags &= ~KASLR_FLAG;
353 sanitize_boot_params(boot_params);
355 if (boot_params->screen_info.orig_video_mode == 7) {
356 vidmem = (char *) 0xb0000;
359 vidmem = (char *) 0xb8000;
363 lines = boot_params->screen_info.orig_video_lines;
364 cols = boot_params->screen_info.orig_video_cols;
367 debug_putstr("early console in extract_kernel\n");
369 free_mem_ptr = heap; /* Heap */
370 free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
372 /* Report initial kernel position details. */
373 debug_putaddr(input_data);
374 debug_putaddr(input_len);
375 debug_putaddr(output);
376 debug_putaddr(output_len);
377 debug_putaddr(run_size);
380 * The memory hole needed for the kernel is the larger of either
381 * the entire decompressed kernel plus relocation table, or the
382 * entire decompressed kernel plus .bss and .brk sections.
384 output = choose_random_location(input_data, input_len, output,
385 output_len > run_size ? output_len
388 /* Validate memory location choices. */
389 if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
390 error("Destination address inappropriately aligned");
392 if (heap > 0x3fffffffffffUL)
393 error("Destination address too large");
395 if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
396 error("Destination address too large");
398 #ifndef CONFIG_RELOCATABLE
399 if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
400 error("Wrong destination address");
403 debug_putstr("\nDecompressing Linux... ");
404 __decompress(input_data, input_len, NULL, NULL, output, output_len,
408 * 32-bit always performs relocations. 64-bit relocations are only
409 * needed if kASLR has chosen a different load address.
411 if (!IS_ENABLED(CONFIG_X86_64) || output != output_orig)
412 handle_relocations(output, output_len);
413 debug_putstr("done.\nBooting the kernel.\n");