4 * This is a collection of several routines from gzip-1.0.3
7 * malloc by Hannu Savolainen 1993 and Matthias Urlichs 1994
8 * puts by Nick Holloway 1993, better puts by Martin Mares 1995
9 * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
13 #include "../string.h"
16 * This code is compiled with -fPIC and it is relocated dynamically
17 * at run time, but no relocation processing is performed.
18 * This means that it is not safe to place pointers in static structures.
22 * Getting to provable safe in place decompression is hard.
23 * Worst case behaviours need to be analyzed.
24 * Background information:
33 * compressed data blocks[N]
36 * resulting in 18 bytes of non compressed data overhead.
38 * Files divided into blocks
39 * 1 bit (last block flag)
42 * 1 block occurs every 32K -1 bytes or when there 50% compression
43 * has been achieved. The smallest block type encoding is always used.
46 * 32 bits length in bytes.
53 * dynamic tree encoding.
57 * The buffer for decompression in place is the length of the
58 * uncompressed data, plus a small amount extra to keep the algorithm safe.
59 * The compressed data is placed at the end of the buffer. The output
60 * pointer is placed at the start of the buffer and the input pointer
61 * is placed where the compressed data starts. Problems will occur
62 * when the output pointer overruns the input pointer.
64 * The output pointer can only overrun the input pointer if the input
65 * pointer is moving faster than the output pointer. A condition only
66 * triggered by data whose compressed form is larger than the uncompressed
69 * The worst case at the block level is a growth of the compressed data
70 * of 5 bytes per 32767 bytes.
72 * The worst case internal to a compressed block is very hard to figure.
73 * The worst case can at least be boundined by having one bit that represents
74 * 32764 bytes and then all of the rest of the bytes representing the very
77 * All of which is enough to compute an amount of extra data that is required
78 * to be safe. To avoid problems at the block level allocating 5 extra bytes
79 * per 32767 bytes of data is sufficient. To avoind problems internal to a
80 * block adding an extra 32767 bytes (the worst case uncompressed block size)
81 * is sufficient, to ensure that in the worst case the decompressed data for
82 * block will stop the byte before the compressed data for a block begins.
83 * To avoid problems with the compressed data's meta information an extra 18
84 * bytes are needed. Leading to the formula:
86 * extra_bytes = (uncompressed_size >> 12) + 32768 + 18 + decompressor_size.
88 * Adding 8 bytes per 32K is a bit excessive but much easier to calculate.
89 * Adding 32768 instead of 32767 just makes for round numbers.
90 * Adding the decompressor_size is necessary as it musht live after all
91 * of the data as well. Last I measured the decompressor is about 14K.
92 * 10K of actual data and 4K of bss.
104 * Use a normal definition of memset() from string.c. There are already
105 * included header files which expect a definition of memset() and by
106 * the time we define memset macro, it is too late.
109 #define memzero(s, n) memset((s), 0, (n))
112 static void error(char *m);
115 * This is set up by the setup-routine at boot-time
117 struct boot_params *real_mode; /* Pointer to real-mode data */
120 memptr free_mem_end_ptr;
124 static int lines, cols;
126 #ifdef CONFIG_KERNEL_GZIP
127 #include "../../../../lib/decompress_inflate.c"
130 #ifdef CONFIG_KERNEL_BZIP2
131 #include "../../../../lib/decompress_bunzip2.c"
134 #ifdef CONFIG_KERNEL_LZMA
135 #include "../../../../lib/decompress_unlzma.c"
138 #ifdef CONFIG_KERNEL_XZ
139 #include "../../../../lib/decompress_unxz.c"
142 #ifdef CONFIG_KERNEL_LZO
143 #include "../../../../lib/decompress_unlzo.c"
146 #ifdef CONFIG_KERNEL_LZ4
147 #include "../../../../lib/decompress_unlz4.c"
150 static void scroll(void)
154 memcpy(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
155 for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
161 #define TXR 0 /* Transmit register (WRITE) */
162 #define LSR 5 /* Line Status */
163 static void serial_putchar(int ch)
165 unsigned timeout = 0xffff;
167 while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
170 outb(ch, early_serial_base + TXR);
173 void __putstr(const char *s)
178 if (early_serial_base) {
182 serial_putchar('\r');
183 serial_putchar(*str++);
187 if (real_mode->screen_info.orig_video_mode == 0 &&
188 lines == 0 && cols == 0)
191 x = real_mode->screen_info.orig_x;
192 y = real_mode->screen_info.orig_y;
194 while ((c = *s++) != '\0') {
202 vidmem[(x + cols * y) * 2] = c;
213 real_mode->screen_info.orig_x = x;
214 real_mode->screen_info.orig_y = y;
216 pos = (x + cols * y) * 2; /* Update cursor position */
218 outb(0xff & (pos >> 9), vidport+1);
220 outb(0xff & (pos >> 1), vidport+1);
223 void __puthex(unsigned long value)
228 for (bits = sizeof(value) * 8 - 4; bits >= 0; bits -= 4) {
229 unsigned long digit = (value >> bits) & 0xf;
232 alpha[0] = '0' + digit;
234 alpha[0] = 'a' + (digit - 0xA);
240 static void error(char *x)
242 error_putstr("\n\n");
244 error_putstr("\n\n -- System halted");
250 #if CONFIG_X86_NEED_RELOCS
251 static void handle_relocations(void *output, unsigned long output_len)
254 unsigned long delta, map, ptr;
255 unsigned long min_addr = (unsigned long)output;
256 unsigned long max_addr = min_addr + output_len;
259 * Calculate the delta between where vmlinux was linked to load
260 * and where it was actually loaded.
262 delta = min_addr - LOAD_PHYSICAL_ADDR;
264 debug_putstr("No relocation needed... ");
267 debug_putstr("Performing relocations... ");
270 * The kernel contains a table of relocation addresses. Those
271 * addresses have the final load address of the kernel in virtual
272 * memory. We are currently working in the self map. So we need to
273 * create an adjustment for kernel memory addresses to the self map.
274 * This will involve subtracting out the base address of the kernel.
276 map = delta - __START_KERNEL_map;
279 * Process relocations: 32 bit relocations first then 64 bit after.
280 * Three sets of binary relocations are added to the end of the kernel
281 * before compression. Each relocation table entry is the kernel
282 * address of the location which needs to be updated stored as a
283 * 32-bit value which is sign extended to 64 bits.
288 * 0 - zero terminator for 64 bit relocations
289 * 64 bit relocation repeated
290 * 0 - zero terminator for inverse 32 bit relocations
291 * 32 bit inverse relocation repeated
292 * 0 - zero terminator for 32 bit relocations
293 * 32 bit relocation repeated
295 * So we work backwards from the end of the decompressed image.
297 for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) {
298 int extended = *reloc;
301 ptr = (unsigned long)extended;
302 if (ptr < min_addr || ptr > max_addr)
303 error("32-bit relocation outside of kernel!\n");
305 *(uint32_t *)ptr += delta;
309 long extended = *reloc;
312 ptr = (unsigned long)extended;
313 if (ptr < min_addr || ptr > max_addr)
314 error("inverse 32-bit relocation outside of kernel!\n");
316 *(int32_t *)ptr -= delta;
318 for (reloc--; *reloc; reloc--) {
319 long extended = *reloc;
322 ptr = (unsigned long)extended;
323 if (ptr < min_addr || ptr > max_addr)
324 error("64-bit relocation outside of kernel!\n");
326 *(uint64_t *)ptr += delta;
331 static inline void handle_relocations(void *output, unsigned long output_len)
335 static void parse_elf(void *output)
339 Elf64_Phdr *phdrs, *phdr;
342 Elf32_Phdr *phdrs, *phdr;
347 memcpy(&ehdr, output, sizeof(ehdr));
348 if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
349 ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
350 ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
351 ehdr.e_ident[EI_MAG3] != ELFMAG3) {
352 error("Kernel is not a valid ELF file");
356 debug_putstr("Parsing ELF... ");
358 phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
360 error("Failed to allocate space for phdrs");
362 memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
364 for (i = 0; i < ehdr.e_phnum; i++) {
367 switch (phdr->p_type) {
369 #ifdef CONFIG_RELOCATABLE
371 dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
373 dest = (void *)(phdr->p_paddr);
376 output + phdr->p_offset,
379 default: /* Ignore other PT_* */ break;
386 asmlinkage __visible void *decompress_kernel(void *rmode, memptr heap,
387 unsigned char *input_data,
388 unsigned long input_len,
389 unsigned char *output,
390 unsigned long output_len,
391 unsigned long run_size)
393 unsigned char *output_orig = output;
397 /* Clear it for solely in-kernel use */
398 real_mode->hdr.loadflags &= ~KASLR_FLAG;
400 sanitize_boot_params(real_mode);
402 if (real_mode->screen_info.orig_video_mode == 7) {
403 vidmem = (char *) 0xb0000;
406 vidmem = (char *) 0xb8000;
410 lines = real_mode->screen_info.orig_video_lines;
411 cols = real_mode->screen_info.orig_video_cols;
414 debug_putstr("early console in decompress_kernel\n");
416 free_mem_ptr = heap; /* Heap */
417 free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
419 /* Report initial kernel position details. */
420 debug_putaddr(input_data);
421 debug_putaddr(input_len);
422 debug_putaddr(output);
423 debug_putaddr(output_len);
424 debug_putaddr(run_size);
427 * The memory hole needed for the kernel is the larger of either
428 * the entire decompressed kernel plus relocation table, or the
429 * entire decompressed kernel plus .bss and .brk sections.
431 output = choose_kernel_location(real_mode, input_data, input_len, output,
432 output_len > run_size ? output_len
435 /* Validate memory location choices. */
436 if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
437 error("Destination address inappropriately aligned");
439 if (heap > 0x3fffffffffffUL)
440 error("Destination address too large");
442 if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
443 error("Destination address too large");
445 #ifndef CONFIG_RELOCATABLE
446 if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
447 error("Wrong destination address");
450 debug_putstr("\nDecompressing Linux... ");
451 __decompress(input_data, input_len, NULL, NULL, output, output_len,
455 * 32-bit always performs relocations. 64-bit relocations are only
456 * needed if kASLR has chosen a different load address.
458 if (!IS_ENABLED(CONFIG_X86_64) || output != output_orig)
459 handle_relocations(output, output_len);
460 debug_putstr("done.\nBooting the kernel.\n");