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
16 #include "../string.h"
17 #include "../voffset.h"
21 * This code is compiled with -fPIC and it is relocated dynamically at
22 * run time, but no relocation processing is performed. This means that
23 * it is not safe to place pointers in static structures.
26 /* Macros used by the included decompressor code below. */
30 * Use normal definitions of mem*() from string.c. There are already
31 * included header files which expect a definition of memset() and by
32 * the time we define memset macro, it is too late.
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 * NOTE: When adding a new decompressor, please update the analysis in
82 static void scroll(void)
86 memmove(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
87 for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
93 #define TXR 0 /* Transmit register (WRITE) */
94 #define LSR 5 /* Line Status */
95 static void serial_putchar(int ch)
97 unsigned timeout = 0xffff;
99 while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
102 outb(ch, early_serial_base + TXR);
105 void __putstr(const char *s)
110 if (early_serial_base) {
114 serial_putchar('\r');
115 serial_putchar(*str++);
119 if (boot_params->screen_info.orig_video_mode == 0 &&
120 lines == 0 && cols == 0)
123 x = boot_params->screen_info.orig_x;
124 y = boot_params->screen_info.orig_y;
126 while ((c = *s++) != '\0') {
134 vidmem[(x + cols * y) * 2] = c;
145 boot_params->screen_info.orig_x = x;
146 boot_params->screen_info.orig_y = y;
148 pos = (x + cols * y) * 2; /* Update cursor position */
150 outb(0xff & (pos >> 9), vidport+1);
152 outb(0xff & (pos >> 1), vidport+1);
155 void __puthex(unsigned long value)
160 for (bits = sizeof(value) * 8 - 4; bits >= 0; bits -= 4) {
161 unsigned long digit = (value >> bits) & 0xf;
164 alpha[0] = '0' + digit;
166 alpha[0] = 'a' + (digit - 0xA);
172 #if CONFIG_X86_NEED_RELOCS
173 static void handle_relocations(void *output, unsigned long output_len,
174 unsigned long virt_addr)
177 unsigned long delta, map, ptr;
178 unsigned long min_addr = (unsigned long)output;
179 unsigned long max_addr = min_addr + (VO___bss_start - VO__text);
182 * Calculate the delta between where vmlinux was linked to load
183 * and where it was actually loaded.
185 delta = min_addr - LOAD_PHYSICAL_ADDR;
188 * The kernel contains a table of relocation addresses. Those
189 * addresses have the final load address of the kernel in virtual
190 * memory. We are currently working in the self map. So we need to
191 * create an adjustment for kernel memory addresses to the self map.
192 * This will involve subtracting out the base address of the kernel.
194 map = delta - __START_KERNEL_map;
197 * 32-bit always performs relocations. 64-bit relocations are only
198 * needed if KASLR has chosen a different starting address offset
199 * from __START_KERNEL_map.
201 if (IS_ENABLED(CONFIG_X86_64))
202 delta = virt_addr - LOAD_PHYSICAL_ADDR;
205 debug_putstr("No relocation needed... ");
208 debug_putstr("Performing relocations... ");
211 * Process relocations: 32 bit relocations first then 64 bit after.
212 * Three sets of binary relocations are added to the end of the kernel
213 * before compression. Each relocation table entry is the kernel
214 * address of the location which needs to be updated stored as a
215 * 32-bit value which is sign extended to 64 bits.
220 * 0 - zero terminator for 64 bit relocations
221 * 64 bit relocation repeated
222 * 0 - zero terminator for inverse 32 bit relocations
223 * 32 bit inverse relocation repeated
224 * 0 - zero terminator for 32 bit relocations
225 * 32 bit relocation repeated
227 * So we work backwards from the end of the decompressed image.
229 for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) {
230 long extended = *reloc;
233 ptr = (unsigned long)extended;
234 if (ptr < min_addr || ptr > max_addr)
235 error("32-bit relocation outside of kernel!\n");
237 *(uint32_t *)ptr += delta;
241 long extended = *reloc;
244 ptr = (unsigned long)extended;
245 if (ptr < min_addr || ptr > max_addr)
246 error("inverse 32-bit relocation outside of kernel!\n");
248 *(int32_t *)ptr -= delta;
250 for (reloc--; *reloc; reloc--) {
251 long extended = *reloc;
254 ptr = (unsigned long)extended;
255 if (ptr < min_addr || ptr > max_addr)
256 error("64-bit relocation outside of kernel!\n");
258 *(uint64_t *)ptr += delta;
263 static inline void handle_relocations(void *output, unsigned long output_len,
264 unsigned long virt_addr)
268 static void parse_elf(void *output)
272 Elf64_Phdr *phdrs, *phdr;
275 Elf32_Phdr *phdrs, *phdr;
280 memcpy(&ehdr, output, sizeof(ehdr));
281 if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
282 ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
283 ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
284 ehdr.e_ident[EI_MAG3] != ELFMAG3) {
285 error("Kernel is not a valid ELF file");
289 debug_putstr("Parsing ELF... ");
291 phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
293 error("Failed to allocate space for phdrs");
295 memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
297 for (i = 0; i < ehdr.e_phnum; i++) {
300 switch (phdr->p_type) {
302 #ifdef CONFIG_RELOCATABLE
304 dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
306 dest = (void *)(phdr->p_paddr);
308 memmove(dest, output + phdr->p_offset, phdr->p_filesz);
310 default: /* Ignore other PT_* */ break;
318 * The compressed kernel image (ZO), has been moved so that its position
319 * is against the end of the buffer used to hold the uncompressed kernel
320 * image (VO) and the execution environment (.bss, .brk), which makes sure
321 * there is room to do the in-place decompression. (See header.S for the
324 * |-----compressed kernel image------|
326 * 0 extract_offset +INIT_SIZE
327 * |-----------|---------------|-------------------------|--------|
329 * VO__text startup_32 of ZO VO__end ZO__end
331 * |-------uncompressed kernel image---------|
334 asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
335 unsigned char *input_data,
336 unsigned long input_len,
337 unsigned char *output,
338 unsigned long output_len)
340 const unsigned long kernel_total_size = VO__end - VO__text;
341 unsigned long virt_addr = (unsigned long)output;
343 /* Retain x86 boot parameters pointer passed from startup_32/64. */
346 /* Clear flags intended for solely in-kernel use. */
347 boot_params->hdr.loadflags &= ~KASLR_FLAG;
349 sanitize_boot_params(boot_params);
351 if (boot_params->screen_info.orig_video_mode == 7) {
352 vidmem = (char *) 0xb0000;
355 vidmem = (char *) 0xb8000;
359 lines = boot_params->screen_info.orig_video_lines;
360 cols = boot_params->screen_info.orig_video_cols;
363 debug_putstr("early console in extract_kernel\n");
365 free_mem_ptr = heap; /* Heap */
366 free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
368 /* Report initial kernel position details. */
369 debug_putaddr(input_data);
370 debug_putaddr(input_len);
371 debug_putaddr(output);
372 debug_putaddr(output_len);
373 debug_putaddr(kernel_total_size);
376 * The memory hole needed for the kernel is the larger of either
377 * the entire decompressed kernel plus relocation table, or the
378 * entire decompressed kernel plus .bss and .brk sections.
380 choose_random_location((unsigned long)input_data, input_len,
381 (unsigned long *)&output,
382 max(output_len, kernel_total_size),
385 /* Validate memory location choices. */
386 if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
387 error("Destination physical address inappropriately aligned");
388 if (virt_addr & (MIN_KERNEL_ALIGN - 1))
389 error("Destination virtual address inappropriately aligned");
391 if (heap > 0x3fffffffffffUL)
392 error("Destination address too large");
394 if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
395 error("Destination address too large");
397 #ifndef CONFIG_RELOCATABLE
398 if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
399 error("Destination address does not match LOAD_PHYSICAL_ADDR");
400 if ((unsigned long)output != virt_addr)
401 error("Destination virtual address changed when not relocatable");
404 debug_putstr("\nDecompressing Linux... ");
405 __decompress(input_data, input_len, NULL, NULL, output, output_len,
408 handle_relocations(output, output_len, virt_addr);
409 debug_putstr("done.\nBooting the kernel.\n");