misc.c revision 13510997d600a076e064f10587a8f6d20f8fff41 
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/*
13 * we have to be careful, because no indirections are allowed here, and
14 * paravirt_ops is a kind of one. As it will only run in baremetal anyway,
15 * we just keep it from happening
16 */
17#undef CONFIG_PARAVIRT
18#ifdef CONFIG_X86_32
19#define _ASM_X86_DESC_H 1
20#endif
21
22#ifdef CONFIG_X86_64
23#define _LINUX_STRING_H_ 1
24#define __LINUX_BITMAP_H 1
25#endif
26
27#include <linux/linkage.h>
28#include <linux/screen_info.h>
29#include <linux/elf.h>
30#include <linux/io.h>
31#include <asm/page.h>
32#include <asm/boot.h>
33#include <asm/bootparam.h>
34
35/* WARNING!!
36 * This code is compiled with -fPIC and it is relocated dynamically
37 * at run time, but no relocation processing is performed.
38 * This means that it is not safe to place pointers in static structures.
39 */
40
41/*
42 * Getting to provable safe in place decompression is hard.
43 * Worst case behaviours need to be analyzed.
44 * Background information:
45 *
46 * The file layout is:
47 *    magic[2]
48 *    method[1]
49 *    flags[1]
50 *    timestamp[4]
51 *    extraflags[1]
52 *    os[1]
53 *    compressed data blocks[N]
54 *    crc[4] orig_len[4]
55 *
56 * resulting in 18 bytes of non compressed data overhead.
57 *
58 * Files divided into blocks
59 * 1 bit (last block flag)
60 * 2 bits (block type)
61 *
62 * 1 block occurs every 32K -1 bytes or when there 50% compression
63 * has been achieved. The smallest block type encoding is always used.
64 *
65 * stored:
66 *    32 bits length in bytes.
67 *
68 * fixed:
69 *    magic fixed tree.
70 *    symbols.
71 *
72 * dynamic:
73 *    dynamic tree encoding.
74 *    symbols.
75 *
76 *
77 * The buffer for decompression in place is the length of the
78 * uncompressed data, plus a small amount extra to keep the algorithm safe.
79 * The compressed data is placed at the end of the buffer.  The output
80 * pointer is placed at the start of the buffer and the input pointer
81 * is placed where the compressed data starts.  Problems will occur
82 * when the output pointer overruns the input pointer.
83 *
84 * The output pointer can only overrun the input pointer if the input
85 * pointer is moving faster than the output pointer.  A condition only
86 * triggered by data whose compressed form is larger than the uncompressed
87 * form.
88 *
89 * The worst case at the block level is a growth of the compressed data
90 * of 5 bytes per 32767 bytes.
91 *
92 * The worst case internal to a compressed block is very hard to figure.
93 * The worst case can at least be boundined by having one bit that represents
94 * 32764 bytes and then all of the rest of the bytes representing the very
95 * very last byte.
96 *
97 * All of which is enough to compute an amount of extra data that is required
98 * to be safe.  To avoid problems at the block level allocating 5 extra bytes
99 * per 32767 bytes of data is sufficient.  To avoind problems internal to a
100 * block adding an extra 32767 bytes (the worst case uncompressed block size)
101 * is sufficient, to ensure that in the worst case the decompressed data for
102 * block will stop the byte before the compressed data for a block begins.
103 * To avoid problems with the compressed data's meta information an extra 18
104 * bytes are needed.  Leading to the formula:
105 *
106 * extra_bytes = (uncompressed_size >> 12) + 32768 + 18 + decompressor_size.
107 *
108 * Adding 8 bytes per 32K is a bit excessive but much easier to calculate.
109 * Adding 32768 instead of 32767 just makes for round numbers.
110 * Adding the decompressor_size is necessary as it musht live after all
111 * of the data as well.  Last I measured the decompressor is about 14K.
112 * 10K of actual data and 4K of bss.
113 *
114 */
115
116/*
117 * gzip declarations
118 */
119#define STATIC		static
120
121#undef memset
122#undef memcpy
123#define memzero(s, n)	memset((s), 0, (n))
124
125
126static void error(char *m);
127
128/*
129 * This is set up by the setup-routine at boot-time
130 */
131static struct boot_params *real_mode;		/* Pointer to real-mode data */
132static int quiet;
133
134static void *memset(void *s, int c, unsigned n);
135void *memcpy(void *dest, const void *src, unsigned n);
136
137static void __putstr(int, const char *);
138#define putstr(__x)  __putstr(0, __x)
139
140#ifdef CONFIG_X86_64
141#define memptr long
142#else
143#define memptr unsigned
144#endif
145
146static memptr free_mem_ptr;
147static memptr free_mem_end_ptr;
148
149static char *vidmem;
150static int vidport;
151static int lines, cols;
152
153#ifdef CONFIG_KERNEL_GZIP
154#include "../../../../lib/decompress_inflate.c"
155#endif
156
157#ifdef CONFIG_KERNEL_BZIP2
158#include "../../../../lib/decompress_bunzip2.c"
159#endif
160
161#ifdef CONFIG_KERNEL_LZMA
162#include "../../../../lib/decompress_unlzma.c"
163#endif
164
165#ifdef CONFIG_KERNEL_LZO
166#include "../../../../lib/decompress_unlzo.c"
167#endif
168
169static void scroll(void)
170{
171	int i;
172
173	memcpy(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
174	for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
175		vidmem[i] = ' ';
176}
177
178static void __putstr(int error, const char *s)
179{
180	int x, y, pos;
181	char c;
182
183#ifndef CONFIG_X86_VERBOSE_BOOTUP
184	if (!error)
185		return;
186#endif
187
188#ifdef CONFIG_X86_32
189	if (real_mode->screen_info.orig_video_mode == 0 &&
190	    lines == 0 && cols == 0)
191		return;
192#endif
193
194	x = real_mode->screen_info.orig_x;
195	y = real_mode->screen_info.orig_y;
196
197	while ((c = *s++) != '\0') {
198		if (c == '\n') {
199			x = 0;
200			if (++y >= lines) {
201				scroll();
202				y--;
203			}
204		} else {
205			vidmem[(x + cols * y) * 2] = c;
206			if (++x >= cols) {
207				x = 0;
208				if (++y >= lines) {
209					scroll();
210					y--;
211				}
212			}
213		}
214	}
215
216	real_mode->screen_info.orig_x = x;
217	real_mode->screen_info.orig_y = y;
218
219	pos = (x + cols * y) * 2;	/* Update cursor position */
220	outb(14, vidport);
221	outb(0xff & (pos >> 9), vidport+1);
222	outb(15, vidport);
223	outb(0xff & (pos >> 1), vidport+1);
224}
225
226static void *memset(void *s, int c, unsigned n)
227{
228	int i;
229	char *ss = s;
230
231	for (i = 0; i < n; i++)
232		ss[i] = c;
233	return s;
234}
235
236void *memcpy(void *dest, const void *src, unsigned n)
237{
238	int i;
239	const char *s = src;
240	char *d = dest;
241
242	for (i = 0; i < n; i++)
243		d[i] = s[i];
244	return dest;
245}
246
247
248static void error(char *x)
249{
250	__putstr(1, "\n\n");
251	__putstr(1, x);
252	__putstr(1, "\n\n -- System halted");
253
254	while (1)
255		asm("hlt");
256}
257
258static void parse_elf(void *output)
259{
260#ifdef CONFIG_X86_64
261	Elf64_Ehdr ehdr;
262	Elf64_Phdr *phdrs, *phdr;
263#else
264	Elf32_Ehdr ehdr;
265	Elf32_Phdr *phdrs, *phdr;
266#endif
267	void *dest;
268	int i;
269
270	memcpy(&ehdr, output, sizeof(ehdr));
271	if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
272	   ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
273	   ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
274	   ehdr.e_ident[EI_MAG3] != ELFMAG3) {
275		error("Kernel is not a valid ELF file");
276		return;
277	}
278
279	if (!quiet)
280		putstr("Parsing ELF... ");
281
282	phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
283	if (!phdrs)
284		error("Failed to allocate space for phdrs");
285
286	memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
287
288	for (i = 0; i < ehdr.e_phnum; i++) {
289		phdr = &phdrs[i];
290
291		switch (phdr->p_type) {
292		case PT_LOAD:
293#ifdef CONFIG_RELOCATABLE
294			dest = output;
295			dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
296#else
297			dest = (void *)(phdr->p_paddr);
298#endif
299			memcpy(dest,
300			       output + phdr->p_offset,
301			       phdr->p_filesz);
302			break;
303		default: /* Ignore other PT_* */ break;
304		}
305	}
306}
307
308asmlinkage void decompress_kernel(void *rmode, memptr heap,
309				  unsigned char *input_data,
310				  unsigned long input_len,
311				  unsigned char *output)
312{
313	real_mode = rmode;
314
315	if (real_mode->hdr.loadflags & QUIET_FLAG)
316		quiet = 1;
317
318	if (real_mode->screen_info.orig_video_mode == 7) {
319		vidmem = (char *) 0xb0000;
320		vidport = 0x3b4;
321	} else {
322		vidmem = (char *) 0xb8000;
323		vidport = 0x3d4;
324	}
325
326	lines = real_mode->screen_info.orig_video_lines;
327	cols = real_mode->screen_info.orig_video_cols;
328
329	free_mem_ptr     = heap;	/* Heap */
330	free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
331
332	if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
333		error("Destination address inappropriately aligned");
334#ifdef CONFIG_X86_64
335	if (heap > 0x3fffffffffffUL)
336		error("Destination address too large");
337#else
338	if (heap > ((-__PAGE_OFFSET-(512<<20)-1) & 0x7fffffff))
339		error("Destination address too large");
340#endif
341#ifndef CONFIG_RELOCATABLE
342	if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
343		error("Wrong destination address");
344#endif
345
346	if (!quiet)
347		putstr("\nDecompressing Linux... ");
348	decompress(input_data, input_len, NULL, NULL, output, NULL, error);
349	parse_elf(output);
350	if (!quiet)
351		putstr("done.\nBooting the kernel.\n");
352	return;
353}
354