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"
18 #include <asm/bootparam_utils.h>
22 * This code is compiled with -fPIC and it is relocated dynamically at
23 * run time, but no relocation processing is performed. This means that
24 * it is not safe to place pointers in static structures.
27 /* Macros used by the included decompressor code below. */
31 * Use normal definitions of mem*() from string.c. There are already
32 * included header files which expect a definition of memset() and by
33 * the time we define memset macro, it is too late.
37 #define memzero(s, n) memset((s), 0, (n))
38 #define memmove memmove
40 /* Functions used by the included decompressor code below. */
41 void *memmove(void *dest, const void *src, size_t n);
44 * This is set up by the setup-routine at boot-time
46 struct boot_params *boot_params;
49 memptr free_mem_end_ptr;
53 static int lines, cols;
55 #ifdef CONFIG_KERNEL_GZIP
56 #include "../../../../lib/decompress_inflate.c"
59 #ifdef CONFIG_KERNEL_BZIP2
60 #include "../../../../lib/decompress_bunzip2.c"
63 #ifdef CONFIG_KERNEL_LZMA
64 #include "../../../../lib/decompress_unlzma.c"
67 #ifdef CONFIG_KERNEL_XZ
68 #include "../../../../lib/decompress_unxz.c"
71 #ifdef CONFIG_KERNEL_LZO
72 #include "../../../../lib/decompress_unlzo.c"
75 #ifdef CONFIG_KERNEL_LZ4
76 #include "../../../../lib/decompress_unlz4.c"
79 * NOTE: When adding a new decompressor, please update the analysis in
83 static void scroll(void)
87 memmove(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
88 for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
94 #define TXR 0 /* Transmit register (WRITE) */
95 #define LSR 5 /* Line Status */
96 static void serial_putchar(int ch)
98 unsigned timeout = 0xffff;
100 while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
103 outb(ch, early_serial_base + TXR);
106 void __putstr(const char *s)
111 if (early_serial_base) {
115 serial_putchar('\r');
116 serial_putchar(*str++);
120 if (boot_params->screen_info.orig_video_mode == 0 &&
121 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 #if CONFIG_X86_NEED_RELOCS
174 static void handle_relocations(void *output, unsigned long output_len,
175 unsigned long virt_addr)
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);
183 * Calculate the delta between where vmlinux was linked to load
184 * and where it was actually loaded.
186 delta = min_addr - LOAD_PHYSICAL_ADDR;
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.
195 map = delta - __START_KERNEL_map;
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.
202 if (IS_ENABLED(CONFIG_X86_64))
203 delta = virt_addr - LOAD_PHYSICAL_ADDR;
206 debug_putstr("No relocation needed... ");
209 debug_putstr("Performing relocations... ");
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.
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
228 * So we work backwards from the end of the decompressed image.
230 for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) {
231 long extended = *reloc;
234 ptr = (unsigned long)extended;
235 if (ptr < min_addr || ptr > max_addr)
236 error("32-bit relocation outside of kernel!\n");
238 *(uint32_t *)ptr += delta;
242 long extended = *reloc;
245 ptr = (unsigned long)extended;
246 if (ptr < min_addr || ptr > max_addr)
247 error("inverse 32-bit relocation outside of kernel!\n");
249 *(int32_t *)ptr -= delta;
251 for (reloc--; *reloc; reloc--) {
252 long extended = *reloc;
255 ptr = (unsigned long)extended;
256 if (ptr < min_addr || ptr > max_addr)
257 error("64-bit relocation outside of kernel!\n");
259 *(uint64_t *)ptr += delta;
264 static inline void handle_relocations(void *output, unsigned long output_len,
265 unsigned long virt_addr)
269 static void parse_elf(void *output)
273 Elf64_Phdr *phdrs, *phdr;
276 Elf32_Phdr *phdrs, *phdr;
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");
290 debug_putstr("Parsing ELF... ");
292 phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
294 error("Failed to allocate space for phdrs");
296 memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
298 for (i = 0; i < ehdr.e_phnum; i++) {
301 switch (phdr->p_type) {
304 if ((phdr->p_align % 0x200000) != 0)
305 error("Alignment of LOAD segment isn't multiple of 2MB");
307 #ifdef CONFIG_RELOCATABLE
309 dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
311 dest = (void *)(phdr->p_paddr);
313 memmove(dest, output + phdr->p_offset, phdr->p_filesz);
315 default: /* Ignore other PT_* */ break;
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
329 * |-----compressed kernel image------|
331 * 0 extract_offset +INIT_SIZE
332 * |-----------|---------------|-------------------------|--------|
334 * VO__text startup_32 of ZO VO__end ZO__end
336 * |-------uncompressed kernel image---------|
339 asmlinkage __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)
345 const unsigned long kernel_total_size = VO__end - VO__text;
346 unsigned long virt_addr = LOAD_PHYSICAL_ADDR;
348 /* Retain x86 boot parameters pointer passed from startup_32/64. */
351 /* Clear flags intended for solely in-kernel use. */
352 boot_params->hdr.loadflags &= ~KASLR_FLAG;
354 sanitize_boot_params(boot_params);
356 if (boot_params->screen_info.orig_video_mode == 7) {
357 vidmem = (char *) 0xb0000;
360 vidmem = (char *) 0xb8000;
364 lines = boot_params->screen_info.orig_video_lines;
365 cols = boot_params->screen_info.orig_video_cols;
368 debug_putstr("early console in extract_kernel\n");
370 free_mem_ptr = heap; /* Heap */
371 free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
373 /* Report initial kernel position details. */
374 debug_putaddr(input_data);
375 debug_putaddr(input_len);
376 debug_putaddr(output);
377 debug_putaddr(output_len);
378 debug_putaddr(kernel_total_size);
381 * The memory hole needed for the kernel is the larger of either
382 * the entire decompressed kernel plus relocation table, or the
383 * entire decompressed kernel plus .bss and .brk sections.
385 choose_random_location((unsigned long)input_data, input_len,
386 (unsigned long *)&output,
387 max(output_len, kernel_total_size),
390 /* Validate memory location choices. */
391 if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
392 error("Destination physical address inappropriately aligned");
393 if (virt_addr & (MIN_KERNEL_ALIGN - 1))
394 error("Destination virtual address inappropriately aligned");
396 if (heap > 0x3fffffffffffUL)
397 error("Destination address too large");
399 if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
400 error("Destination address too large");
402 #ifndef CONFIG_RELOCATABLE
403 if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
404 error("Destination address does not match LOAD_PHYSICAL_ADDR");
405 if (virt_addr != LOAD_PHYSICAL_ADDR)
406 error("Destination virtual address changed when not relocatable");
409 debug_putstr("\nDecompressing Linux... ");
410 __decompress(input_data, input_len, NULL, NULL, output, output_len,
413 handle_relocations(output, output_len, virt_addr);
414 debug_putstr("done.\nBooting the kernel.\n");