xref: /openbmc/linux/arch/x86/boot/compressed/misc.c (revision 6774def6)
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 
112 static void error(char *m);
113 
114 /*
115  * This is set up by the setup-routine at boot-time
116  */
117 struct boot_params *real_mode;		/* Pointer to real-mode data */
118 
119 memptr free_mem_ptr;
120 memptr free_mem_end_ptr;
121 
122 static char *vidmem;
123 static int vidport;
124 static 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 
150 static 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               */
163 static 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 
173 void __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 
223 static 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
234 static 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
302 static inline void handle_relocations(void *output, unsigned long output_len)
303 { }
304 #endif
305 
306 static 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 
357 asmlinkage __visible 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 				  unsigned long run_size)
363 {
364 	real_mode = rmode;
365 
366 	sanitize_boot_params(real_mode);
367 
368 	if (real_mode->screen_info.orig_video_mode == 7) {
369 		vidmem = (char *) 0xb0000;
370 		vidport = 0x3b4;
371 	} else {
372 		vidmem = (char *) 0xb8000;
373 		vidport = 0x3d4;
374 	}
375 
376 	lines = real_mode->screen_info.orig_video_lines;
377 	cols = real_mode->screen_info.orig_video_cols;
378 
379 	console_init();
380 	debug_putstr("early console in decompress_kernel\n");
381 
382 	free_mem_ptr     = heap;	/* Heap */
383 	free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
384 
385 	/*
386 	 * The memory hole needed for the kernel is the larger of either
387 	 * the entire decompressed kernel plus relocation table, or the
388 	 * entire decompressed kernel plus .bss and .brk sections.
389 	 */
390 	output = choose_kernel_location(input_data, input_len, output,
391 					output_len > run_size ? output_len
392 							      : run_size);
393 
394 	/* Validate memory location choices. */
395 	if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
396 		error("Destination address inappropriately aligned");
397 #ifdef CONFIG_X86_64
398 	if (heap > 0x3fffffffffffUL)
399 		error("Destination address too large");
400 #else
401 	if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
402 		error("Destination address too large");
403 #endif
404 #ifndef CONFIG_RELOCATABLE
405 	if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
406 		error("Wrong destination address");
407 #endif
408 
409 	debug_putstr("\nDecompressing Linux... ");
410 	decompress(input_data, input_len, NULL, NULL, output, NULL, error);
411 	parse_elf(output);
412 	handle_relocations(output, output_len);
413 	debug_putstr("done.\nBooting the kernel.\n");
414 	return output;
415 }
416