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Linux/arch/x86/boot/compressed/misc.c

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  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 
 14 /* WARNING!!
 15  * This code is compiled with -fPIC and it is relocated dynamically
 16  * at run time, but no relocation processing is performed.
 17  * This means that it is not safe to place pointers in static structures.
 18  */
 19 
 20 /*
 21  * Getting to provable safe in place decompression is hard.
 22  * Worst case behaviours need to be analyzed.
 23  * Background information:
 24  *
 25  * The file layout is:
 26  *    magic[2]
 27  *    method[1]
 28  *    flags[1]
 29  *    timestamp[4]
 30  *    extraflags[1]
 31  *    os[1]
 32  *    compressed data blocks[N]
 33  *    crc[4] orig_len[4]
 34  *
 35  * resulting in 18 bytes of non compressed data overhead.
 36  *
 37  * Files divided into blocks
 38  * 1 bit (last block flag)
 39  * 2 bits (block type)
 40  *
 41  * 1 block occurs every 32K -1 bytes or when there 50% compression
 42  * has been achieved. The smallest block type encoding is always used.
 43  *
 44  * stored:
 45  *    32 bits length in bytes.
 46  *
 47  * fixed:
 48  *    magic fixed tree.
 49  *    symbols.
 50  *
 51  * dynamic:
 52  *    dynamic tree encoding.
 53  *    symbols.
 54  *
 55  *
 56  * The buffer for decompression in place is the length of the
 57  * uncompressed data, plus a small amount extra to keep the algorithm safe.
 58  * The compressed data is placed at the end of the buffer.  The output
 59  * pointer is placed at the start of the buffer and the input pointer
 60  * is placed where the compressed data starts.  Problems will occur
 61  * when the output pointer overruns the input pointer.
 62  *
 63  * The output pointer can only overrun the input pointer if the input
 64  * pointer is moving faster than the output pointer.  A condition only
 65  * triggered by data whose compressed form is larger than the uncompressed
 66  * form.
 67  *
 68  * The worst case at the block level is a growth of the compressed data
 69  * of 5 bytes per 32767 bytes.
 70  *
 71  * The worst case internal to a compressed block is very hard to figure.
 72  * The worst case can at least be boundined by having one bit that represents
 73  * 32764 bytes and then all of the rest of the bytes representing the very
 74  * very last byte.
 75  *
 76  * All of which is enough to compute an amount of extra data that is required
 77  * to be safe.  To avoid problems at the block level allocating 5 extra bytes
 78  * per 32767 bytes of data is sufficient.  To avoind problems internal to a
 79  * block adding an extra 32767 bytes (the worst case uncompressed block size)
 80  * is sufficient, to ensure that in the worst case the decompressed data for
 81  * block will stop the byte before the compressed data for a block begins.
 82  * To avoid problems with the compressed data's meta information an extra 18
 83  * bytes are needed.  Leading to the formula:
 84  *
 85  * extra_bytes = (uncompressed_size >> 12) + 32768 + 18 + decompressor_size.
 86  *
 87  * Adding 8 bytes per 32K is a bit excessive but much easier to calculate.
 88  * Adding 32768 instead of 32767 just makes for round numbers.
 89  * Adding the decompressor_size is necessary as it musht live after all
 90  * of the data as well.  Last I measured the decompressor is about 14K.
 91  * 10K of actual data and 4K of bss.
 92  *
 93  */
 94 
 95 /*
 96  * gzip declarations
 97  */
 98 #define STATIC          static
 99 
100 #undef memset
101 #undef memcpy
102 #define memzero(s, n)   memset((s), 0, (n))
103 
104 
105 static void error(char *m);
106 
107 /*
108  * This is set up by the setup-routine at boot-time
109  */
110 struct boot_params *real_mode;          /* Pointer to real-mode data */
111 
112 void *memset(void *s, int c, size_t n);
113 void *memcpy(void *dest, const void *src, size_t n);
114 
115 #ifdef CONFIG_X86_64
116 #define memptr long
117 #else
118 #define memptr unsigned
119 #endif
120 
121 static memptr free_mem_ptr;
122 static memptr free_mem_end_ptr;
123 
124 static char *vidmem;
125 static int vidport;
126 static int lines, cols;
127 
128 #ifdef CONFIG_KERNEL_GZIP
129 #include "../../../../lib/decompress_inflate.c"
130 #endif
131 
132 #ifdef CONFIG_KERNEL_BZIP2
133 #include "../../../../lib/decompress_bunzip2.c"
134 #endif
135 
136 #ifdef CONFIG_KERNEL_LZMA
137 #include "../../../../lib/decompress_unlzma.c"
138 #endif
139 
140 #ifdef CONFIG_KERNEL_XZ
141 #include "../../../../lib/decompress_unxz.c"
142 #endif
143 
144 #ifdef CONFIG_KERNEL_LZO
145 #include "../../../../lib/decompress_unlzo.c"
146 #endif
147 
148 static void scroll(void)
149 {
150         int i;
151 
152         memcpy(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
153         for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
154                 vidmem[i] = ' ';
155 }
156 
157 #define XMTRDY          0x20
158 
159 #define TXR             0       /*  Transmit register (WRITE) */
160 #define LSR             5       /*  Line Status               */
161 static void serial_putchar(int ch)
162 {
163         unsigned timeout = 0xffff;
164 
165         while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
166                 cpu_relax();
167 
168         outb(ch, early_serial_base + TXR);
169 }
170 
171 void __putstr(const char *s)
172 {
173         int x, y, pos;
174         char c;
175 
176         if (early_serial_base) {
177                 const char *str = s;
178                 while (*str) {
179                         if (*str == '\n')
180                                 serial_putchar('\r');
181                         serial_putchar(*str++);
182                 }
183         }
184 
185         if (real_mode->screen_info.orig_video_mode == 0 &&
186             lines == 0 && cols == 0)
187                 return;
188 
189         x = real_mode->screen_info.orig_x;
190         y = real_mode->screen_info.orig_y;
191 
192         while ((c = *s++) != '\0') {
193                 if (c == '\n') {
194                         x = 0;
195                         if (++y >= lines) {
196                                 scroll();
197                                 y--;
198                         }
199                 } else {
200                         vidmem[(x + cols * y) * 2] = c;
201                         if (++x >= cols) {
202                                 x = 0;
203                                 if (++y >= lines) {
204                                         scroll();
205                                         y--;
206                                 }
207                         }
208                 }
209         }
210 
211         real_mode->screen_info.orig_x = x;
212         real_mode->screen_info.orig_y = y;
213 
214         pos = (x + cols * y) * 2;       /* Update cursor position */
215         outb(14, vidport);
216         outb(0xff & (pos >> 9), vidport+1);
217         outb(15, vidport);
218         outb(0xff & (pos >> 1), vidport+1);
219 }
220 
221 void *memset(void *s, int c, size_t n)
222 {
223         int i;
224         char *ss = s;
225 
226         for (i = 0; i < n; i++)
227                 ss[i] = c;
228         return s;
229 }
230 #ifdef CONFIG_X86_32
231 void *memcpy(void *dest, const void *src, size_t n)
232 {
233         int d0, d1, d2;
234         asm volatile(
235                 "rep ; movsl\n\t"
236                 "movl %4,%%ecx\n\t"
237                 "rep ; movsb\n\t"
238                 : "=&c" (d0), "=&D" (d1), "=&S" (d2)
239                 : "" (n >> 2), "g" (n & 3), "1" (dest), "2" (src)
240                 : "memory");
241 
242         return dest;
243 }
244 #else
245 void *memcpy(void *dest, const void *src, size_t n)
246 {
247         long d0, d1, d2;
248         asm volatile(
249                 "rep ; movsq\n\t"
250                 "movq %4,%%rcx\n\t"
251                 "rep ; movsb\n\t"
252                 : "=&c" (d0), "=&D" (d1), "=&S" (d2)
253                 : "" (n >> 3), "g" (n & 7), "1" (dest), "2" (src)
254                 : "memory");
255 
256         return dest;
257 }
258 #endif
259 
260 static void error(char *x)
261 {
262         error_putstr("\n\n");
263         error_putstr(x);
264         error_putstr("\n\n -- System halted");
265 
266         while (1)
267                 asm("hlt");
268 }
269 
270 static void parse_elf(void *output)
271 {
272 #ifdef CONFIG_X86_64
273         Elf64_Ehdr ehdr;
274         Elf64_Phdr *phdrs, *phdr;
275 #else
276         Elf32_Ehdr ehdr;
277         Elf32_Phdr *phdrs, *phdr;
278 #endif
279         void *dest;
280         int i;
281 
282         memcpy(&ehdr, output, sizeof(ehdr));
283         if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
284            ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
285            ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
286            ehdr.e_ident[EI_MAG3] != ELFMAG3) {
287                 error("Kernel is not a valid ELF file");
288                 return;
289         }
290 
291         debug_putstr("Parsing ELF... ");
292 
293         phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum);
294         if (!phdrs)
295                 error("Failed to allocate space for phdrs");
296 
297         memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum);
298 
299         for (i = 0; i < ehdr.e_phnum; i++) {
300                 phdr = &phdrs[i];
301 
302                 switch (phdr->p_type) {
303                 case PT_LOAD:
304 #ifdef CONFIG_RELOCATABLE
305                         dest = output;
306                         dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR);
307 #else
308                         dest = (void *)(phdr->p_paddr);
309 #endif
310                         memcpy(dest,
311                                output + phdr->p_offset,
312                                phdr->p_filesz);
313                         break;
314                 default: /* Ignore other PT_* */ break;
315                 }
316         }
317 
318         free(phdrs);
319 }
320 
321 asmlinkage void decompress_kernel(void *rmode, memptr heap,
322                                   unsigned char *input_data,
323                                   unsigned long input_len,
324                                   unsigned char *output)
325 {
326         real_mode = rmode;
327 
328         if (real_mode->screen_info.orig_video_mode == 7) {
329                 vidmem = (char *) 0xb0000;
330                 vidport = 0x3b4;
331         } else {
332                 vidmem = (char *) 0xb8000;
333                 vidport = 0x3d4;
334         }
335 
336         lines = real_mode->screen_info.orig_video_lines;
337         cols = real_mode->screen_info.orig_video_cols;
338 
339         console_init();
340         debug_putstr("early console in decompress_kernel\n");
341 
342         free_mem_ptr     = heap;        /* Heap */
343         free_mem_end_ptr = heap + BOOT_HEAP_SIZE;
344 
345         if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1))
346                 error("Destination address inappropriately aligned");
347 #ifdef CONFIG_X86_64
348         if (heap > 0x3fffffffffffUL)
349                 error("Destination address too large");
350 #else
351         if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
352                 error("Destination address too large");
353 #endif
354 #ifndef CONFIG_RELOCATABLE
355         if ((unsigned long)output != LOAD_PHYSICAL_ADDR)
356                 error("Wrong destination address");
357 #endif
358 
359         debug_putstr("\nDecompressing Linux... ");
360         decompress(input_data, input_len, NULL, NULL, output, NULL, error);
361         parse_elf(output);
362         debug_putstr("done.\nBooting the kernel.\n");
363         return;
364 }
365 

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