xref: /openbmc/linux/arch/x86/boot/compressed/misc.c (revision b6dcefde)
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 
126 static void error(char *m);
127 
128 /*
129  * This is set up by the setup-routine at boot-time
130  */
131 static struct boot_params *real_mode;		/* Pointer to real-mode data */
132 static int quiet;
133 
134 static void *memset(void *s, int c, unsigned n);
135 void *memcpy(void *dest, const void *src, unsigned n);
136 
137 static 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 
146 static memptr free_mem_ptr;
147 static memptr free_mem_end_ptr;
148 
149 static char *vidmem;
150 static int vidport;
151 static 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 
169 static 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 
178 static 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 
226 static 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 
236 void *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 
248 static 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 
258 static 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 
308 asmlinkage 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