misc.c revision 5dcd14ecd41ea2b3ae3295a9b30d98769d52165f 
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
148static void scroll(void)
149{
150	int i;
151
152	memcpy(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
153	for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
154		vidmem[i] = ' ';
155}
156
157#define XMTRDY          0x20
158
159#define TXR             0       /*  Transmit register (WRITE) */
160#define LSR             5       /*  Line Status               */
161static void serial_putchar(int ch)
162{
163	unsigned timeout = 0xffff;
164
165	while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
166		cpu_relax();
167
168	outb(ch, early_serial_base + TXR);
169}
170
171void __putstr(const char *s)
172{
173	int x, y, pos;
174	char c;
175
176	if (early_serial_base) {
177		const char *str = s;
178		while (*str) {
179			if (*str == '\n')
180				serial_putchar('\r');
181			serial_putchar(*str++);
182		}
183	}
184
185	if (real_mode->screen_info.orig_video_mode == 0 &&
186	    lines == 0 && cols == 0)
187		return;
188
189	x = real_mode->screen_info.orig_x;
190	y = real_mode->screen_info.orig_y;
191
192	while ((c = *s++) != '\0') {
193		if (c == '\n') {
194			x = 0;
195			if (++y >= lines) {
196				scroll();
197				y--;
198			}
199		} else {
200			vidmem[(x + cols * y) * 2] = c;
201			if (++x >= cols) {
202				x = 0;
203				if (++y >= lines) {
204					scroll();
205					y--;
206				}
207			}
208		}
209	}
210
211	real_mode->screen_info.orig_x = x;
212	real_mode->screen_info.orig_y = y;
213
214	pos = (x + cols * y) * 2;	/* Update cursor position */
215	outb(14, vidport);
216	outb(0xff & (pos >> 9), vidport+1);
217	outb(15, vidport);
218	outb(0xff & (pos >> 1), vidport+1);
219}
220
221void *memset(void *s, int c, size_t n)
222{
223	int i;
224	char *ss = s;
225
226	for (i = 0; i < n; i++)
227		ss[i] = c;
228	return s;
229}
230#ifdef CONFIG_X86_32
231void *memcpy(void *dest, const void *src, size_t n)
232{
233	int d0, d1, d2;
234	asm volatile(
235		"rep ; movsl\n\t"
236		"movl %4,%%ecx\n\t"
237		"rep ; movsb\n\t"
238		: "=&c" (d0), "=&D" (d1), "=&S" (d2)
239		: "0" (n >> 2), "g" (n & 3), "1" (dest), "2" (src)
240		: "memory");
241
242	return dest;
243}
244#else
245void *memcpy(void *dest, const void *src, size_t n)
246{
247	long d0, d1, d2;
248	asm volatile(
249		"rep ; movsq\n\t"
250		"movq %4,%%rcx\n\t"
251		"rep ; movsb\n\t"
252		: "=&c" (d0), "=&D" (d1), "=&S" (d2)
253		: "0" (n >> 3), "g" (n & 7), "1" (dest), "2" (src)
254		: "memory");
255
256	return dest;
257}
258#endif
259
260static void error(char *x)
261{
262	error_putstr("\n\n");
263	error_putstr(x);
264	error_putstr("\n\n -- System halted");
265
266	while (1)
267		asm("hlt");
268}
269
270static void parse_elf(void *output)
271{
272#ifdef CONFIG_X86_64
273	Elf64_Ehdr ehdr;
274	Elf64_Phdr *phdrs, *phdr;
275#else
276	Elf32_Ehdr ehdr;
277	Elf32_Phdr *phdrs, *phdr;
278#endif
279	void *dest;
280	int i;
281
282	memcpy(&ehdr, output, sizeof(ehdr));
283	if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
284	   ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
285	   ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
286	   ehdr.e_ident[EI_MAG3] != ELFMAG3) {
287		error("Kernel is not a valid ELF file");
288		return;
289	}
290
291	debug_putstr("Parsing ELF... ");
292
293	phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
294	if (!phdrs)
295		error("Failed to allocate space for phdrs");
296
297	memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
298
299	for (i = 0; i < ehdr.e_phnum; i++) {
300		phdr = &phdrs[i];
301
302		switch (phdr->p_type) {
303		case PT_LOAD:
304#ifdef CONFIG_RELOCATABLE
305			dest = output;
306			dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
307#else
308			dest = (void *)(phdr->p_paddr);
309#endif
310			memcpy(dest,
311			       output + phdr->p_offset,
312			       phdr->p_filesz);
313			break;
314		default: /* Ignore other PT_* */ break;
315		}
316	}
317
318	free(phdrs);
319}
320
321asmlinkage void decompress_kernel(void *rmode, memptr heap,
322				  unsigned char *input_data,
323				  unsigned long input_len,
324				  unsigned char *output)
325{
326	real_mode = rmode;
327
328	sanitize_boot_params(real_mode);
329
330	if (real_mode->screen_info.orig_video_mode == 7) {
331		vidmem = (char *) 0xb0000;
332		vidport = 0x3b4;
333	} else {
334		vidmem = (char *) 0xb8000;
335		vidport = 0x3d4;
336	}
337
338	lines = real_mode->screen_info.orig_video_lines;
339	cols = real_mode->screen_info.orig_video_cols;
340
341	console_init();
342	debug_putstr("early console in decompress_kernel\n");
343
344	free_mem_ptr     = heap;	/* Heap */
345	free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
346
347	if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
348		error("Destination address inappropriately aligned");
349#ifdef CONFIG_X86_64
350	if (heap > 0x3fffffffffffUL)
351		error("Destination address too large");
352#else
353	if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
354		error("Destination address too large");
355#endif
356#ifndef CONFIG_RELOCATABLE
357	if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
358		error("Wrong destination address");
359#endif
360
361	debug_putstr("\nDecompressing Linux... ");
362	decompress(input_data, input_len, NULL, NULL, output, NULL, error);
363	parse_elf(output);
364	debug_putstr("done.\nBooting the kernel.\n");
365	return;
366}
367