misc.c revision 04999550f93234bf05597a9b7d26e2bfe27ba883 
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#include "../string.h"
14
15/* WARNING!!
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.
19 */
20
21/*
22 * Getting to provable safe in place decompression is hard.
23 * Worst case behaviours need to be analyzed.
24 * Background information:
25 *
26 * The file layout is:
27 *    magic[2]
28 *    method[1]
29 *    flags[1]
30 *    timestamp[4]
31 *    extraflags[1]
32 *    os[1]
33 *    compressed data blocks[N]
34 *    crc[4] orig_len[4]
35 *
36 * resulting in 18 bytes of non compressed data overhead.
37 *
38 * Files divided into blocks
39 * 1 bit (last block flag)
40 * 2 bits (block type)
41 *
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.
44 *
45 * stored:
46 *    32 bits length in bytes.
47 *
48 * fixed:
49 *    magic fixed tree.
50 *    symbols.
51 *
52 * dynamic:
53 *    dynamic tree encoding.
54 *    symbols.
55 *
56 *
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.
63 *
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
67 * form.
68 *
69 * The worst case at the block level is a growth of the compressed data
70 * of 5 bytes per 32767 bytes.
71 *
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
75 * very last byte.
76 *
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:
85 *
86 * extra_bytes = (uncompressed_size >> 12) + 32768 + 18 + decompressor_size.
87 *
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.
93 *
94 */
95
96/*
97 * gzip declarations
98 */
99#define STATIC		static
100
101#undef memcpy
102
103/*
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.
107 */
108#undef memset
109#define memzero(s, n)	memset((s), 0, (n))
110
111
112static void error(char *m);
113
114/*
115 * This is set up by the setup-routine at boot-time
116 */
117struct boot_params *real_mode;		/* Pointer to real-mode data */
118
119memptr free_mem_ptr;
120memptr free_mem_end_ptr;
121
122static char *vidmem;
123static int vidport;
124static int lines, cols;
125
126#ifdef CONFIG_KERNEL_GZIP
127#include "../../../../lib/decompress_inflate.c"
128#endif
129
130#ifdef CONFIG_KERNEL_BZIP2
131#include "../../../../lib/decompress_bunzip2.c"
132#endif
133
134#ifdef CONFIG_KERNEL_LZMA
135#include "../../../../lib/decompress_unlzma.c"
136#endif
137
138#ifdef CONFIG_KERNEL_XZ
139#include "../../../../lib/decompress_unxz.c"
140#endif
141
142#ifdef CONFIG_KERNEL_LZO
143#include "../../../../lib/decompress_unlzo.c"
144#endif
145
146#ifdef CONFIG_KERNEL_LZ4
147#include "../../../../lib/decompress_unlz4.c"
148#endif
149
150static void scroll(void)
151{
152	int i;
153
154	memcpy(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
155	for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
156		vidmem[i] = ' ';
157}
158
159#define XMTRDY          0x20
160
161#define TXR             0       /*  Transmit register (WRITE) */
162#define LSR             5       /*  Line Status               */
163static void serial_putchar(int ch)
164{
165	unsigned timeout = 0xffff;
166
167	while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
168		cpu_relax();
169
170	outb(ch, early_serial_base + TXR);
171}
172
173void __putstr(const char *s)
174{
175	int x, y, pos;
176	char c;
177
178	if (early_serial_base) {
179		const char *str = s;
180		while (*str) {
181			if (*str == '\n')
182				serial_putchar('\r');
183			serial_putchar(*str++);
184		}
185	}
186
187	if (real_mode->screen_info.orig_video_mode == 0 &&
188	    lines == 0 && cols == 0)
189		return;
190
191	x = real_mode->screen_info.orig_x;
192	y = real_mode->screen_info.orig_y;
193
194	while ((c = *s++) != '\0') {
195		if (c == '\n') {
196			x = 0;
197			if (++y >= lines) {
198				scroll();
199				y--;
200			}
201		} else {
202			vidmem[(x + cols * y) * 2] = c;
203			if (++x >= cols) {
204				x = 0;
205				if (++y >= lines) {
206					scroll();
207					y--;
208				}
209			}
210		}
211	}
212
213	real_mode->screen_info.orig_x = x;
214	real_mode->screen_info.orig_y = y;
215
216	pos = (x + cols * y) * 2;	/* Update cursor position */
217	outb(14, vidport);
218	outb(0xff & (pos >> 9), vidport+1);
219	outb(15, vidport);
220	outb(0xff & (pos >> 1), vidport+1);
221}
222
223static void error(char *x)
224{
225	error_putstr("\n\n");
226	error_putstr(x);
227	error_putstr("\n\n -- System halted");
228
229	while (1)
230		asm("hlt");
231}
232
233#if CONFIG_X86_NEED_RELOCS
234static void handle_relocations(void *output, unsigned long output_len)
235{
236	int *reloc;
237	unsigned long delta, map, ptr;
238	unsigned long min_addr = (unsigned long)output;
239	unsigned long max_addr = min_addr + output_len;
240
241	/*
242	 * Calculate the delta between where vmlinux was linked to load
243	 * and where it was actually loaded.
244	 */
245	delta = min_addr - LOAD_PHYSICAL_ADDR;
246	if (!delta) {
247		debug_putstr("No relocation needed... ");
248		return;
249	}
250	debug_putstr("Performing relocations... ");
251
252	/*
253	 * The kernel contains a table of relocation addresses. Those
254	 * addresses have the final load address of the kernel in virtual
255	 * memory. We are currently working in the self map. So we need to
256	 * create an adjustment for kernel memory addresses to the self map.
257	 * This will involve subtracting out the base address of the kernel.
258	 */
259	map = delta - __START_KERNEL_map;
260
261	/*
262	 * Process relocations: 32 bit relocations first then 64 bit after.
263	 * Two sets of binary relocations are added to the end of the kernel
264	 * before compression. Each relocation table entry is the kernel
265	 * address of the location which needs to be updated stored as a
266	 * 32-bit value which is sign extended to 64 bits.
267	 *
268	 * Format is:
269	 *
270	 * kernel bits...
271	 * 0 - zero terminator for 64 bit relocations
272	 * 64 bit relocation repeated
273	 * 0 - zero terminator for 32 bit relocations
274	 * 32 bit relocation repeated
275	 *
276	 * So we work backwards from the end of the decompressed image.
277	 */
278	for (reloc = output + output_len - sizeof(*reloc); *reloc; reloc--) {
279		int extended = *reloc;
280		extended += map;
281
282		ptr = (unsigned long)extended;
283		if (ptr < min_addr || ptr > max_addr)
284			error("32-bit relocation outside of kernel!\n");
285
286		*(uint32_t *)ptr += delta;
287	}
288#ifdef CONFIG_X86_64
289	for (reloc--; *reloc; reloc--) {
290		long extended = *reloc;
291		extended += map;
292
293		ptr = (unsigned long)extended;
294		if (ptr < min_addr || ptr > max_addr)
295			error("64-bit relocation outside of kernel!\n");
296
297		*(uint64_t *)ptr += delta;
298	}
299#endif
300}
301#else
302static inline void handle_relocations(void *output, unsigned long output_len)
303{ }
304#endif
305
306static void parse_elf(void *output)
307{
308#ifdef CONFIG_X86_64
309	Elf64_Ehdr ehdr;
310	Elf64_Phdr *phdrs, *phdr;
311#else
312	Elf32_Ehdr ehdr;
313	Elf32_Phdr *phdrs, *phdr;
314#endif
315	void *dest;
316	int i;
317
318	memcpy(&ehdr, output, sizeof(ehdr));
319	if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
320	   ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
321	   ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
322	   ehdr.e_ident[EI_MAG3] != ELFMAG3) {
323		error("Kernel is not a valid ELF file");
324		return;
325	}
326
327	debug_putstr("Parsing ELF... ");
328
329	phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
330	if (!phdrs)
331		error("Failed to allocate space for phdrs");
332
333	memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
334
335	for (i = 0; i < ehdr.e_phnum; i++) {
336		phdr = &phdrs[i];
337
338		switch (phdr->p_type) {
339		case PT_LOAD:
340#ifdef CONFIG_RELOCATABLE
341			dest = output;
342			dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
343#else
344			dest = (void *)(phdr->p_paddr);
345#endif
346			memcpy(dest,
347			       output + phdr->p_offset,
348			       phdr->p_filesz);
349			break;
350		default: /* Ignore other PT_* */ break;
351		}
352	}
353
354	free(phdrs);
355}
356
357asmlinkage void *decompress_kernel(void *rmode, memptr heap,
358				  unsigned char *input_data,
359				  unsigned long input_len,
360				  unsigned char *output,
361				  unsigned long output_len)
362{
363	real_mode = rmode;
364
365	sanitize_boot_params(real_mode);
366
367	if (real_mode->screen_info.orig_video_mode == 7) {
368		vidmem = (char *) 0xb0000;
369		vidport = 0x3b4;
370	} else {
371		vidmem = (char *) 0xb8000;
372		vidport = 0x3d4;
373	}
374
375	lines = real_mode->screen_info.orig_video_lines;
376	cols = real_mode->screen_info.orig_video_cols;
377
378	console_init();
379	debug_putstr("early console in decompress_kernel\n");
380
381	free_mem_ptr     = heap;	/* Heap */
382	free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
383
384	output = choose_kernel_location(input_data, input_len,
385					output, output_len);
386
387	/* Validate memory location choices. */
388	if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
389		error("Destination address inappropriately aligned");
390#ifdef CONFIG_X86_64
391	if (heap > 0x3fffffffffffUL)
392		error("Destination address too large");
393#else
394	if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
395		error("Destination address too large");
396#endif
397#ifndef CONFIG_RELOCATABLE
398	if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
399		error("Wrong destination address");
400#endif
401
402	debug_putstr("\nDecompressing Linux... ");
403	decompress(input_data, input_len, NULL, NULL, output, NULL, error);
404	parse_elf(output);
405	handle_relocations(output, output_len);
406	debug_putstr("done.\nBooting the kernel.\n");
407	return output;
408}
409