summaryrefslogtreecommitdiff
path: root/arch/x86/boot/compressed/misc.c
blob: bc5553b496f719c665ed1e7876eae3e0f2d69b1a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
/*
 * misc.c
 *
 * This is a collection of several routines from gzip-1.0.3
 * adapted for Linux.
 *
 * malloc by Hannu Savolainen 1993 and Matthias Urlichs 1994
 * puts by Nick Holloway 1993, better puts by Martin Mares 1995
 * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
 */

/*
 * we have to be careful, because no indirections are allowed here, and
 * paravirt_ops is a kind of one. As it will only run in baremetal anyway,
 * we just keep it from happening
 */
#undef CONFIG_PARAVIRT
#ifdef CONFIG_X86_32
#define _ASM_DESC_H_ 1
#endif

#ifdef CONFIG_X86_64
#define _LINUX_STRING_H_ 1
#define __LINUX_BITMAP_H 1
#endif

#include <linux/linkage.h>
#include <linux/screen_info.h>
#include <linux/elf.h>
#include <asm/io.h>
#include <asm/page.h>
#include <asm/boot.h>
#include <asm/bootparam.h>

/* WARNING!!
 * This code is compiled with -fPIC and it is relocated dynamically
 * at run time, but no relocation processing is performed.
 * This means that it is not safe to place pointers in static structures.
 */

/*
 * Getting to provable safe in place decompression is hard.
 * Worst case behaviours need to be analyzed.
 * Background information:
 *
 * The file layout is:
 *    magic[2]
 *    method[1]
 *    flags[1]
 *    timestamp[4]
 *    extraflags[1]
 *    os[1]
 *    compressed data blocks[N]
 *    crc[4] orig_len[4]
 *
 * resulting in 18 bytes of non compressed data overhead.
 *
 * Files divided into blocks
 * 1 bit (last block flag)
 * 2 bits (block type)
 *
 * 1 block occurs every 32K -1 bytes or when there 50% compression
 * has been achieved. The smallest block type encoding is always used.
 *
 * stored:
 *    32 bits length in bytes.
 *
 * fixed:
 *    magic fixed tree.
 *    symbols.
 *
 * dynamic:
 *    dynamic tree encoding.
 *    symbols.
 *
 *
 * The buffer for decompression in place is the length of the
 * uncompressed data, plus a small amount extra to keep the algorithm safe.
 * The compressed data is placed at the end of the buffer.  The output
 * pointer is placed at the start of the buffer and the input pointer
 * is placed where the compressed data starts.  Problems will occur
 * when the output pointer overruns the input pointer.
 *
 * The output pointer can only overrun the input pointer if the input
 * pointer is moving faster than the output pointer.  A condition only
 * triggered by data whose compressed form is larger than the uncompressed
 * form.
 *
 * The worst case at the block level is a growth of the compressed data
 * of 5 bytes per 32767 bytes.
 *
 * The worst case internal to a compressed block is very hard to figure.
 * The worst case can at least be boundined by having one bit that represents
 * 32764 bytes and then all of the rest of the bytes representing the very
 * very last byte.
 *
 * All of which is enough to compute an amount of extra data that is required
 * to be safe.  To avoid problems at the block level allocating 5 extra bytes
 * per 32767 bytes of data is sufficient.  To avoind problems internal to a
 * block adding an extra 32767 bytes (the worst case uncompressed block size)
 * is sufficient, to ensure that in the worst case the decompressed data for
 * block will stop the byte before the compressed data for a block begins.
 * To avoid problems with the compressed data's meta information an extra 18
 * bytes are needed.  Leading to the formula:
 *
 * extra_bytes = (uncompressed_size >> 12) + 32768 + 18 + decompressor_size.
 *
 * Adding 8 bytes per 32K is a bit excessive but much easier to calculate.
 * Adding 32768 instead of 32767 just makes for round numbers.
 * Adding the decompressor_size is necessary as it musht live after all
 * of the data as well.  Last I measured the decompressor is about 14K.
 * 10K of actual data and 4K of bss.
 *
 */

/*
 * gzip declarations
 */

#define OF(args)	args
#define STATIC		static

#undef memset
#undef memcpy
#define memzero(s, n)	memset((s), 0, (n))

typedef unsigned char	uch;
typedef unsigned short	ush;
typedef unsigned long	ulg;

/*
 * Window size must be at least 32k, and a power of two.
 * We don't actually have a window just a huge output buffer,
 * so we report a 2G window size, as that should always be
 * larger than our output buffer:
 */
#define WSIZE		0x80000000

/* Input buffer: */
static unsigned char	*inbuf;

/* Sliding window buffer (and final output buffer): */
static unsigned char	*window;

/* Valid bytes in inbuf: */
static unsigned		insize;

/* Index of next byte to be processed in inbuf: */
static unsigned		inptr;

/* Bytes in output buffer: */
static unsigned		outcnt;

/* gzip flag byte */
#define ASCII_FLAG	0x01 /* bit 0 set: file probably ASCII text */
#define CONTINUATION	0x02 /* bit 1 set: continuation of multi-part gz file */
#define EXTRA_FIELD	0x04 /* bit 2 set: extra field present */
#define ORIG_NAM	0x08 /* bit 3 set: original file name present */
#define COMMENT		0x10 /* bit 4 set: file comment present */
#define ENCRYPTED	0x20 /* bit 5 set: file is encrypted */
#define RESERVED	0xC0 /* bit 6, 7:  reserved */

#define get_byte()	(inptr < insize ? inbuf[inptr++] : fill_inbuf())

/* Diagnostic functions */
#ifdef DEBUG
#  define Assert(cond, msg) do { if (!(cond)) error(msg); } while (0)
#  define Trace(x)	do { fprintf x; } while (0)
#  define Tracev(x)	do { if (verbose) fprintf x ; } while (0)
#  define Tracevv(x)	do { if (verbose > 1) fprintf x ; } while (0)
#  define Tracec(c, x)	do { if (verbose && (c)) fprintf x ; } while (0)
#  define Tracecv(c, x)	do { if (verbose > 1 && (c)) fprintf x ; } while (0)
#else
#  define Assert(cond, msg)
#  define Trace(x)
#  define Tracev(x)
#  define Tracevv(x)
#  define Tracec(c, x)
#  define Tracecv(c, x)
#endif

static int  fill_inbuf(void);
static void flush_window(void);
static void error(char *m);
static void gzip_mark(void **);
static void gzip_release(void **);

/*
 * This is set up by the setup-routine at boot-time
 */
static struct boot_params *real_mode;		/* Pointer to real-mode data */
static int quiet;

extern unsigned char input_data[];
extern int input_len;

static long bytes_out;

static void *malloc(int size);
static void free(void *where);

static void *memset(void *s, int c, unsigned n);
static void *memcpy(void *dest, const void *src, unsigned n);

static void __putstr(int, const char *);
#define putstr(__x)  __putstr(0, __x)

#ifdef CONFIG_X86_64
#define memptr long
#else
#define memptr unsigned
#endif

static memptr free_mem_ptr;
static memptr free_mem_end_ptr;

static char *vidmem;
static int vidport;
static int lines, cols;

#include "../../../../lib/inflate.c"

static void *malloc(int size)
{
	void *p;

	if (size < 0)
		error("Malloc error");
	if (free_mem_ptr <= 0)
		error("Memory error");

	free_mem_ptr = (free_mem_ptr + 3) & ~3;	/* Align */

	p = (void *)free_mem_ptr;
	free_mem_ptr += size;

	if (free_mem_ptr >= free_mem_end_ptr)
		error("Out of memory");

	return p;
}

static void free(void *where)
{	/* Don't care */
}

static void gzip_mark(void **ptr)
{
	*ptr = (void *) free_mem_ptr;
}

static void gzip_release(void **ptr)
{
	free_mem_ptr = (memptr) *ptr;
}

static void scroll(void)
{
	int i;

	memcpy(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
	for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
		vidmem[i] = ' ';
}

static void __putstr(int error, const char *s)
{
	int x, y, pos;
	char c;

#ifndef CONFIG_X86_VERBOSE_BOOTUP
	if (!error)
		return;
#endif

#ifdef CONFIG_X86_32
	if (real_mode->screen_info.orig_video_mode == 0 &&
	    lines == 0 && cols == 0)
		return;
#endif

	x = real_mode->screen_info.orig_x;
	y = real_mode->screen_info.orig_y;

	while ((c = *s++) != '\0') {
		if (c == '\n') {
			x = 0;
			if (++y >= lines) {
				scroll();
				y--;
			}
		} else {
			vidmem [(x + cols * y) * 2] = c;
			if (++x >= cols) {
				x = 0;
				if (++y >= lines) {
					scroll();
					y--;
				}
			}
		}
	}

	real_mode->screen_info.orig_x = x;
	real_mode->screen_info.orig_y = y;

	pos = (x + cols * y) * 2;	/* Update cursor position */
	outb(14, vidport);
	outb(0xff & (pos >> 9), vidport+1);
	outb(15, vidport);
	outb(0xff & (pos >> 1), vidport+1);
}

static void *memset(void *s, int c, unsigned n)
{
	int i;
	char *ss = s;

	for (i = 0; i < n; i++) ss[i] = c;
	return s;
}

static void *memcpy(void *dest, const void *src, unsigned n)
{
	int i;
	const char *s = src;
	char *d = dest;

	for (i = 0; i < n; i++) d[i] = s[i];
	return dest;
}

/* ===========================================================================
 * Fill the input buffer. This is called only when the buffer is empty
 * and at least one byte is really needed.
 */
static int fill_inbuf(void)
{
	error("ran out of input data");
	return 0;
}

/* ===========================================================================
 * Write the output window window[0..outcnt-1] and update crc and bytes_out.
 * (Used for the decompressed data only.)
 */
static void flush_window(void)
{
	/* With my window equal to my output buffer
	 * I only need to compute the crc here.
	 */
	unsigned long c = crc;         /* temporary variable */
	unsigned n;
	unsigned char *in, ch;

	in = window;
	for (n = 0; n < outcnt; n++) {
		ch = *in++;
		c = crc_32_tab[((int)c ^ ch) & 0xff] ^ (c >> 8);
	}
	crc = c;
	bytes_out += (unsigned long)outcnt;
	outcnt = 0;
}

static void error(char *x)
{
	__putstr(1, "\n\n");
	__putstr(1, x);
	__putstr(1, "\n\n -- System halted");

	while (1)
		asm("hlt");
}

static void parse_elf(void *output)
{
#ifdef CONFIG_X86_64
	Elf64_Ehdr ehdr;
	Elf64_Phdr *phdrs, *phdr;
#else
	Elf32_Ehdr ehdr;
	Elf32_Phdr *phdrs, *phdr;
#endif
	void *dest;
	int i;

	memcpy(&ehdr, output, sizeof(ehdr));
	if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
	   ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
	   ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
	   ehdr.e_ident[EI_MAG3] != ELFMAG3) {
		error("Kernel is not a valid ELF file");
		return;
	}

	if (!quiet)
		putstr("Parsing ELF... ");

	phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
	if (!phdrs)
		error("Failed to allocate space for phdrs");

	memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);

	for (i = 0; i < ehdr.e_phnum; i++) {
		phdr = &phdrs[i];

		switch (phdr->p_type) {
		case PT_LOAD:
#ifdef CONFIG_RELOCATABLE
			dest = output;
			dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
#else
			dest = (void *)(phdr->p_paddr);
#endif
			memcpy(dest,
			       output + phdr->p_offset,
			       phdr->p_filesz);
			break;
		default: /* Ignore other PT_* */ break;
		}
	}
}

asmlinkage void decompress_kernel(void *rmode, memptr heap,
				  unsigned char *input_data,
				  unsigned long input_len,
				  unsigned char *output)
{
	real_mode = rmode;

	if (real_mode->hdr.loadflags & QUIET_FLAG)
		quiet = 1;

	if (real_mode->screen_info.orig_video_mode == 7) {
		vidmem = (char *) 0xb0000;
		vidport = 0x3b4;
	} else {
		vidmem = (char *) 0xb8000;
		vidport = 0x3d4;
	}

	lines = real_mode->screen_info.orig_video_lines;
	cols = real_mode->screen_info.orig_video_cols;

	window = output;		/* Output buffer (Normally at 1M) */
	free_mem_ptr     = heap;	/* Heap */
	free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
	inbuf  = input_data;		/* Input buffer */
	insize = input_len;
	inptr  = 0;

#ifdef CONFIG_X86_64
	if ((unsigned long)output & (__KERNEL_ALIGN - 1))
		error("Destination address not 2M aligned");
	if ((unsigned long)output >= 0xffffffffffUL)
		error("Destination address too large");
#else
	if ((u32)output & (CONFIG_PHYSICAL_ALIGN - 1))
		error("Destination address not CONFIG_PHYSICAL_ALIGN aligned");
	if (heap > ((-__PAGE_OFFSET-(512<<20)-1) & 0x7fffffff))
		error("Destination address too large");
#ifndef CONFIG_RELOCATABLE
	if ((u32)output != LOAD_PHYSICAL_ADDR)
		error("Wrong destination address");
#endif
#endif

	makecrc();
	if (!quiet)
		putstr("\nDecompressing Linux... ");
	gunzip();
	parse_elf(output);
	if (!quiet)
		putstr("done.\nBooting the kernel.\n");
	return;
}