misc.c revision 8ab3820fd5b2896d66da7bb2a906bc382e63e7bc 
1/*
2 * misc.c
3 *
4 * This is a collection of several routines from gzip-1.0.3
5 * adapted for Linux.
6 *
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
10 */
11
12#include "misc.h"
13
14/* WARNING!!
15 * This code is compiled with -fPIC and it is relocated dynamically
16 * at run time, but no relocation processing is performed.
17 * This means that it is not safe to place pointers in static structures.
18 */
19
20/*
21 * Getting to provable safe in place decompression is hard.
22 * Worst case behaviours need to be analyzed.
23 * Background information:
24 *
25 * The file layout is:
26 *    magic[2]
27 *    method[1]
28 *    flags[1]
29 *    timestamp[4]
30 *    extraflags[1]
31 *    os[1]
32 *    compressed data blocks[N]
33 *    crc[4] orig_len[4]
34 *
35 * resulting in 18 bytes of non compressed data overhead.
36 *
37 * Files divided into blocks
38 * 1 bit (last block flag)
39 * 2 bits (block type)
40 *
41 * 1 block occurs every 32K -1 bytes or when there 50% compression
42 * has been achieved. The smallest block type encoding is always used.
43 *
44 * stored:
45 *    32 bits length in bytes.
46 *
47 * fixed:
48 *    magic fixed tree.
49 *    symbols.
50 *
51 * dynamic:
52 *    dynamic tree encoding.
53 *    symbols.
54 *
55 *
56 * The buffer for decompression in place is the length of the
57 * uncompressed data, plus a small amount extra to keep the algorithm safe.
58 * The compressed data is placed at the end of the buffer.  The output
59 * pointer is placed at the start of the buffer and the input pointer
60 * is placed where the compressed data starts.  Problems will occur
61 * when the output pointer overruns the input pointer.
62 *
63 * The output pointer can only overrun the input pointer if the input
64 * pointer is moving faster than the output pointer.  A condition only
65 * triggered by data whose compressed form is larger than the uncompressed
66 * form.
67 *
68 * The worst case at the block level is a growth of the compressed data
69 * of 5 bytes per 32767 bytes.
70 *
71 * The worst case internal to a compressed block is very hard to figure.
72 * The worst case can at least be boundined by having one bit that represents
73 * 32764 bytes and then all of the rest of the bytes representing the very
74 * very last byte.
75 *
76 * All of which is enough to compute an amount of extra data that is required
77 * to be safe.  To avoid problems at the block level allocating 5 extra bytes
78 * per 32767 bytes of data is sufficient.  To avoind problems internal to a
79 * block adding an extra 32767 bytes (the worst case uncompressed block size)
80 * is sufficient, to ensure that in the worst case the decompressed data for
81 * block will stop the byte before the compressed data for a block begins.
82 * To avoid problems with the compressed data's meta information an extra 18
83 * bytes are needed.  Leading to the formula:
84 *
85 * extra_bytes = (uncompressed_size >> 12) + 32768 + 18 + decompressor_size.
86 *
87 * Adding 8 bytes per 32K is a bit excessive but much easier to calculate.
88 * Adding 32768 instead of 32767 just makes for round numbers.
89 * Adding the decompressor_size is necessary as it musht live after all
90 * of the data as well.  Last I measured the decompressor is about 14K.
91 * 10K of actual data and 4K of bss.
92 *
93 */
94
95/*
96 * gzip declarations
97 */
98#define STATIC		static
99
100#undef memset
101#undef memcpy
102#define memzero(s, n)	memset((s), 0, (n))
103
104
105static void error(char *m);
106
107/*
108 * This is set up by the setup-routine at boot-time
109 */
110struct boot_params *real_mode;		/* Pointer to real-mode data */
111
112void *memset(void *s, int c, size_t n);
113void *memcpy(void *dest, const void *src, size_t n);
114
115#ifdef CONFIG_X86_64
116#define memptr long
117#else
118#define memptr unsigned
119#endif
120
121static memptr free_mem_ptr;
122static memptr free_mem_end_ptr;
123
124static char *vidmem;
125static int vidport;
126static int lines, cols;
127
128#ifdef CONFIG_KERNEL_GZIP
129#include "../../../../lib/decompress_inflate.c"
130#endif
131
132#ifdef CONFIG_KERNEL_BZIP2
133#include "../../../../lib/decompress_bunzip2.c"
134#endif
135
136#ifdef CONFIG_KERNEL_LZMA
137#include "../../../../lib/decompress_unlzma.c"
138#endif
139
140#ifdef CONFIG_KERNEL_XZ
141#include "../../../../lib/decompress_unxz.c"
142#endif
143
144#ifdef CONFIG_KERNEL_LZO
145#include "../../../../lib/decompress_unlzo.c"
146#endif
147
148#ifdef CONFIG_KERNEL_LZ4
149#include "../../../../lib/decompress_unlz4.c"
150#endif
151
152static void scroll(void)
153{
154	int i;
155
156	memcpy(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
157	for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
158		vidmem[i] = ' ';
159}
160
161#define XMTRDY          0x20
162
163#define TXR             0       /*  Transmit register (WRITE) */
164#define LSR             5       /*  Line Status               */
165static void serial_putchar(int ch)
166{
167	unsigned timeout = 0xffff;
168
169	while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
170		cpu_relax();
171
172	outb(ch, early_serial_base + TXR);
173}
174
175void __putstr(const char *s)
176{
177	int x, y, pos;
178	char c;
179
180	if (early_serial_base) {
181		const char *str = s;
182		while (*str) {
183			if (*str == '\n')
184				serial_putchar('\r');
185			serial_putchar(*str++);
186		}
187	}
188
189	if (real_mode->screen_info.orig_video_mode == 0 &&
190	    lines == 0 && cols == 0)
191		return;
192
193	x = real_mode->screen_info.orig_x;
194	y = real_mode->screen_info.orig_y;
195
196	while ((c = *s++) != '\0') {
197		if (c == '\n') {
198			x = 0;
199			if (++y >= lines) {
200				scroll();
201				y--;
202			}
203		} else {
204			vidmem[(x + cols * y) * 2] = c;
205			if (++x >= cols) {
206				x = 0;
207				if (++y >= lines) {
208					scroll();
209					y--;
210				}
211			}
212		}
213	}
214
215	real_mode->screen_info.orig_x = x;
216	real_mode->screen_info.orig_y = y;
217
218	pos = (x + cols * y) * 2;	/* Update cursor position */
219	outb(14, vidport);
220	outb(0xff & (pos >> 9), vidport+1);
221	outb(15, vidport);
222	outb(0xff & (pos >> 1), vidport+1);
223}
224
225void *memset(void *s, int c, size_t n)
226{
227	int i;
228	char *ss = s;
229
230	for (i = 0; i < n; i++)
231		ss[i] = c;
232	return s;
233}
234#ifdef CONFIG_X86_32
235void *memcpy(void *dest, const void *src, size_t n)
236{
237	int d0, d1, d2;
238	asm volatile(
239		"rep ; movsl\n\t"
240		"movl %4,%%ecx\n\t"
241		"rep ; movsb\n\t"
242		: "=&c" (d0), "=&D" (d1), "=&S" (d2)
243		: "0" (n >> 2), "g" (n & 3), "1" (dest), "2" (src)
244		: "memory");
245
246	return dest;
247}
248#else
249void *memcpy(void *dest, const void *src, size_t n)
250{
251	long d0, d1, d2;
252	asm volatile(
253		"rep ; movsq\n\t"
254		"movq %4,%%rcx\n\t"
255		"rep ; movsb\n\t"
256		: "=&c" (d0), "=&D" (d1), "=&S" (d2)
257		: "0" (n >> 3), "g" (n & 7), "1" (dest), "2" (src)
258		: "memory");
259
260	return dest;
261}
262#endif
263
264static void error(char *x)
265{
266	error_putstr("\n\n");
267	error_putstr(x);
268	error_putstr("\n\n -- System halted");
269
270	while (1)
271		asm("hlt");
272}
273
274#if CONFIG_X86_NEED_RELOCS
275static void handle_relocations(void *output, unsigned long output_len)
276{
277	int *reloc;
278	unsigned long delta, map, ptr;
279	unsigned long min_addr = (unsigned long)output;
280	unsigned long max_addr = min_addr + output_len;
281
282	/*
283	 * Calculate the delta between where vmlinux was linked to load
284	 * and where it was actually loaded.
285	 */
286	delta = min_addr - LOAD_PHYSICAL_ADDR;
287	if (!delta) {
288		debug_putstr("No relocation needed... ");
289		return;
290	}
291	debug_putstr("Performing relocations... ");
292
293	/*
294	 * The kernel contains a table of relocation addresses. Those
295	 * addresses have the final load address of the kernel in virtual
296	 * memory. We are currently working in the self map. So we need to
297	 * create an adjustment for kernel memory addresses to the self map.
298	 * This will involve subtracting out the base address of the kernel.
299	 */
300	map = delta - __START_KERNEL_map;
301
302	/*
303	 * Process relocations: 32 bit relocations first then 64 bit after.
304	 * Two sets of binary relocations are added to the end of the kernel
305	 * before compression. Each relocation table entry is the kernel
306	 * address of the location which needs to be updated stored as a
307	 * 32-bit value which is sign extended to 64 bits.
308	 *
309	 * Format is:
310	 *
311	 * kernel bits...
312	 * 0 - zero terminator for 64 bit relocations
313	 * 64 bit relocation repeated
314	 * 0 - zero terminator for 32 bit relocations
315	 * 32 bit relocation repeated
316	 *
317	 * So we work backwards from the end of the decompressed image.
318	 */
319	for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) {
320		int extended = *reloc;
321		extended += map;
322
323		ptr = (unsigned long)extended;
324		if (ptr < min_addr || ptr > max_addr)
325			error("32-bit relocation outside of kernel!\n");
326
327		*(uint32_t *)ptr += delta;
328	}
329#ifdef CONFIG_X86_64
330	for (reloc--; *reloc; reloc--) {
331		long extended = *reloc;
332		extended += map;
333
334		ptr = (unsigned long)extended;
335		if (ptr < min_addr || ptr > max_addr)
336			error("64-bit relocation outside of kernel!\n");
337
338		*(uint64_t *)ptr += delta;
339	}
340#endif
341}
342#else
343static inline void handle_relocations(void *output, unsigned long output_len)
344{ }
345#endif
346
347static void parse_elf(void *output)
348{
349#ifdef CONFIG_X86_64
350	Elf64_Ehdr ehdr;
351	Elf64_Phdr *phdrs, *phdr;
352#else
353	Elf32_Ehdr ehdr;
354	Elf32_Phdr *phdrs, *phdr;
355#endif
356	void *dest;
357	int i;
358
359	memcpy(&ehdr, output, sizeof(ehdr));
360	if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
361	   ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
362	   ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
363	   ehdr.e_ident[EI_MAG3] != ELFMAG3) {
364		error("Kernel is not a valid ELF file");
365		return;
366	}
367
368	debug_putstr("Parsing ELF... ");
369
370	phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
371	if (!phdrs)
372		error("Failed to allocate space for phdrs");
373
374	memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
375
376	for (i = 0; i < ehdr.e_phnum; i++) {
377		phdr = &phdrs[i];
378
379		switch (phdr->p_type) {
380		case PT_LOAD:
381#ifdef CONFIG_RELOCATABLE
382			dest = output;
383			dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
384#else
385			dest = (void *)(phdr->p_paddr);
386#endif
387			memcpy(dest,
388			       output + phdr->p_offset,
389			       phdr->p_filesz);
390			break;
391		default: /* Ignore other PT_* */ break;
392		}
393	}
394
395	free(phdrs);
396}
397
398asmlinkage void *decompress_kernel(void *rmode, memptr heap,
399				  unsigned char *input_data,
400				  unsigned long input_len,
401				  unsigned char *output,
402				  unsigned long output_len)
403{
404	real_mode = rmode;
405
406	sanitize_boot_params(real_mode);
407
408	if (real_mode->screen_info.orig_video_mode == 7) {
409		vidmem = (char *) 0xb0000;
410		vidport = 0x3b4;
411	} else {
412		vidmem = (char *) 0xb8000;
413		vidport = 0x3d4;
414	}
415
416	lines = real_mode->screen_info.orig_video_lines;
417	cols = real_mode->screen_info.orig_video_cols;
418
419	console_init();
420	debug_putstr("early console in decompress_kernel\n");
421
422	free_mem_ptr     = heap;	/* Heap */
423	free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
424
425	output = choose_kernel_location(input_data, input_len,
426					output, output_len);
427
428	/* Validate memory location choices. */
429	if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
430		error("Destination address inappropriately aligned");
431#ifdef CONFIG_X86_64
432	if (heap > 0x3fffffffffffUL)
433		error("Destination address too large");
434#else
435	if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
436		error("Destination address too large");
437#endif
438#ifndef CONFIG_RELOCATABLE
439	if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
440		error("Wrong destination address");
441#endif
442
443	debug_putstr("\nDecompressing Linux... ");
444	decompress(input_data, input_len, NULL, NULL, output, NULL, error);
445	parse_elf(output);
446	handle_relocations(output, output_len);
447	debug_putstr("done.\nBooting the kernel.\n");
448	return output;
449}
450