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1da177e Linux-2.6.12-rc2
Linus Torvalds authored
1 /* Generate assembler source containing symbol information
2 *
3 * Copyright 2002 by Kai Germaschewski
4 *
5 * This software may be used and distributed according to the terms
6 * of the GNU General Public License, incorporated herein by reference.
7 *
8 * Usage: nm -n vmlinux | scripts/kallsyms [--all-symbols] > symbols.S
9 *
10 * ChangeLog:
11 *
12 * (25/Aug/2004) Paulo Marques <pmarques@grupopie.com>
13 * Changed the compression method from stem compression to "table lookup"
14 * compression
15 *
16 * Table compression uses all the unused char codes on the symbols and
17 * maps these to the most used substrings (tokens). For instance, it might
18 * map char code 0xF7 to represent "write_" and then in every symbol where
19 * "write_" appears it can be replaced by 0xF7, saving 5 bytes.
20 * The used codes themselves are also placed in the table so that the
21 * decompresion can work without "special cases".
22 * Applied to kernel symbols, this usually produces a compression ratio
23 * of about 50%.
24 *
25 */
26
27 #include <stdio.h>
28 #include <stdlib.h>
29 #include <string.h>
30 #include <ctype.h>
31
32 #define KSYM_NAME_LEN 127
33
34
35 struct sym_entry {
36 unsigned long long addr;
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37 unsigned int len;
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
38 unsigned char *sym;
39 };
40
41
42 static struct sym_entry *table;
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43 static unsigned int table_size, table_cnt;
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ebiederm authored
44 static unsigned long long _text, _stext, _etext, _sinittext, _einittext, _sextratext, _eextratext;
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
45 static int all_symbols = 0;
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ysat0 authored
46 static char symbol_prefix_char = '\0';
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47
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48 int token_profit[0x10000];
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49
50 /* the table that holds the result of the compression */
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51 unsigned char best_table[256][2];
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52 unsigned char best_table_len[256];
53
54
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55 static void usage(void)
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Linus Torvalds authored
56 {
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ysat0 authored
57 fprintf(stderr, "Usage: kallsyms [--all-symbols] [--symbol-prefix=<prefix char>] < in.map > out.S\n");
1da177e Linux-2.6.12-rc2
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58 exit(1);
59 }
60
61 /*
62 * This ignores the intensely annoying "mapping symbols" found
63 * in ARM ELF files: $a, $t and $d.
64 */
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65 static inline int is_arm_mapping_symbol(const char *str)
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66 {
67 return str[0] == '$' && strchr("atd", str[1])
68 && (str[2] == '\0' || str[2] == '.');
69 }
70
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71 static int read_symbol(FILE *in, struct sym_entry *s)
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72 {
73 char str[500];
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74 char *sym, stype;
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75 int rc;
76
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77 rc = fscanf(in, "%llx %c %499s\n", &s->addr, &stype, str);
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78 if (rc != 3) {
79 if (rc != EOF) {
80 /* skip line */
81 fgets(str, 500, in);
82 }
83 return -1;
84 }
85
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ysat0 authored
86 sym = str;
87 /* skip prefix char */
88 if (symbol_prefix_char && str[0] == symbol_prefix_char)
89 sym++;
90
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91 /* Ignore most absolute/undefined (?) symbols. */
fd593d1 @ebiederm [PATCH] relocatable kernel: Kallsyms generate relocatable symbols
ebiederm authored
92 if (strcmp(sym, "_text") == 0)
93 _text = s->addr;
94 else if (strcmp(sym, "_stext") == 0)
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95 _stext = s->addr;
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96 else if (strcmp(sym, "_etext") == 0)
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97 _etext = s->addr;
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98 else if (strcmp(sym, "_sinittext") == 0)
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99 _sinittext = s->addr;
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ysat0 authored
100 else if (strcmp(sym, "_einittext") == 0)
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101 _einittext = s->addr;
075d6eb @dwmw2 [PATCH] ppc32: platform-specific functions missing from kallsyms.
dwmw2 authored
102 else if (strcmp(sym, "_sextratext") == 0)
103 _sextratext = s->addr;
104 else if (strcmp(sym, "_eextratext") == 0)
105 _eextratext = s->addr;
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106 else if (toupper(stype) == 'A')
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107 {
108 /* Keep these useful absolute symbols */
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109 if (strcmp(sym, "__kernel_syscall_via_break") &&
110 strcmp(sym, "__kernel_syscall_via_epc") &&
111 strcmp(sym, "__kernel_sigtramp") &&
112 strcmp(sym, "__gp"))
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113 return -1;
114
115 }
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116 else if (toupper(stype) == 'U' ||
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117 is_arm_mapping_symbol(sym))
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118 return -1;
6f00df2 @ralfbaechle [PATCH] Strip local symbols from kallsyms
ralfbaechle authored
119 /* exclude also MIPS ELF local symbols ($L123 instead of .L123) */
120 else if (str[0] == '$')
121 return -1;
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122
123 /* include the type field in the symbol name, so that it gets
124 * compressed together */
125 s->len = strlen(str) + 1;
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126 s->sym = malloc(s->len + 1);
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127 if (!s->sym) {
128 fprintf(stderr, "kallsyms failure: "
129 "unable to allocate required amount of memory\n");
130 exit(EXIT_FAILURE);
131 }
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132 strcpy((char *)s->sym + 1, str);
133 s->sym[0] = stype;
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134
135 return 0;
136 }
137
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138 static int symbol_valid(struct sym_entry *s)
1da177e Linux-2.6.12-rc2
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139 {
140 /* Symbols which vary between passes. Passes 1 and 2 must have
141 * identical symbol lists. The kallsyms_* symbols below are only added
142 * after pass 1, they would be included in pass 2 when --all-symbols is
143 * specified so exclude them to get a stable symbol list.
144 */
145 static char *special_symbols[] = {
146 "kallsyms_addresses",
147 "kallsyms_num_syms",
148 "kallsyms_names",
149 "kallsyms_markers",
150 "kallsyms_token_table",
151 "kallsyms_token_index",
152
153 /* Exclude linker generated symbols which vary between passes */
154 "_SDA_BASE_", /* ppc */
155 "_SDA2_BASE_", /* ppc */
156 NULL };
157 int i;
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158 int offset = 1;
159
160 /* skip prefix char */
161 if (symbol_prefix_char && *(s->sym + 1) == symbol_prefix_char)
162 offset++;
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163
164 /* if --all-symbols is not specified, then symbols outside the text
165 * and inittext sections are discarded */
166 if (!all_symbols) {
167 if ((s->addr < _stext || s->addr > _etext)
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dwmw2 authored
168 && (s->addr < _sinittext || s->addr > _einittext)
169 && (s->addr < _sextratext || s->addr > _eextratext))
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170 return 0;
171 /* Corner case. Discard any symbols with the same value as
075d6eb @dwmw2 [PATCH] ppc32: platform-specific functions missing from kallsyms.
dwmw2 authored
172 * _etext _einittext or _eextratext; they can move between pass
173 * 1 and 2 when the kallsyms data are added. If these symbols
174 * move then they may get dropped in pass 2, which breaks the
175 * kallsyms rules.
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176 */
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J.A. Magallon authored
177 if ((s->addr == _etext && strcmp((char*)s->sym + offset, "_etext")) ||
178 (s->addr == _einittext && strcmp((char*)s->sym + offset, "_einittext")) ||
179 (s->addr == _eextratext && strcmp((char*)s->sym + offset, "_eextratext")))
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180 return 0;
181 }
182
183 /* Exclude symbols which vary between passes. */
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184 if (strstr((char *)s->sym + offset, "_compiled."))
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185 return 0;
186
187 for (i = 0; special_symbols[i]; i++)
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188 if( strcmp((char *)s->sym + offset, special_symbols[i]) == 0 )
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189 return 0;
190
191 return 1;
192 }
193
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194 static void read_map(FILE *in)
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195 {
196 while (!feof(in)) {
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197 if (table_cnt >= table_size) {
198 table_size += 10000;
199 table = realloc(table, sizeof(*table) * table_size);
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200 if (!table) {
201 fprintf(stderr, "out of memory\n");
202 exit (1);
203 }
204 }
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205 if (read_symbol(in, &table[table_cnt]) == 0)
206 table_cnt++;
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207 }
208 }
209
210 static void output_label(char *label)
211 {
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212 if (symbol_prefix_char)
213 printf(".globl %c%s\n", symbol_prefix_char, label);
214 else
215 printf(".globl %s\n", label);
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216 printf("\tALGN\n");
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217 if (symbol_prefix_char)
218 printf("%c%s:\n", symbol_prefix_char, label);
219 else
220 printf("%s:\n", label);
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221 }
222
223 /* uncompress a compressed symbol. When this function is called, the best table
224 * might still be compressed itself, so the function needs to be recursive */
225 static int expand_symbol(unsigned char *data, int len, char *result)
226 {
227 int c, rlen, total=0;
228
229 while (len) {
230 c = *data;
231 /* if the table holds a single char that is the same as the one
232 * we are looking for, then end the search */
233 if (best_table[c][0]==c && best_table_len[c]==1) {
234 *result++ = c;
235 total++;
236 } else {
237 /* if not, recurse and expand */
238 rlen = expand_symbol(best_table[c], best_table_len[c], result);
239 total += rlen;
240 result += rlen;
241 }
242 data++;
243 len--;
244 }
245 *result=0;
246
247 return total;
248 }
249
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250 static void write_src(void)
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251 {
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252 unsigned int i, k, off;
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253 unsigned int best_idx[256];
254 unsigned int *markers;
255 char buf[KSYM_NAME_LEN+1];
256
257 printf("#include <asm/types.h>\n");
258 printf("#if BITS_PER_LONG == 64\n");
259 printf("#define PTR .quad\n");
260 printf("#define ALGN .align 8\n");
261 printf("#else\n");
262 printf("#define PTR .long\n");
263 printf("#define ALGN .align 4\n");
264 printf("#endif\n");
265
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Jan Beulich authored
266 printf("\t.section .rodata, \"a\"\n");
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267
fd593d1 @ebiederm [PATCH] relocatable kernel: Kallsyms generate relocatable symbols
ebiederm authored
268 /* Provide proper symbols relocatability by their '_text'
269 * relativeness. The symbol names cannot be used to construct
270 * normal symbol references as the list of symbols contains
271 * symbols that are declared static and are private to their
272 * .o files. This prevents .tmp_kallsyms.o or any other
273 * object from referencing them.
274 */
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275 output_label("kallsyms_addresses");
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276 for (i = 0; i < table_cnt; i++) {
fd593d1 @ebiederm [PATCH] relocatable kernel: Kallsyms generate relocatable symbols
ebiederm authored
277 if (toupper(table[i].sym[0]) != 'A') {
2c22d8b [PATCH] relocatable kernel: Fix kallsyms on avr32 after relocatable k…
Vivek Goyal authored
278 if (_text <= table[i].addr)
279 printf("\tPTR\t_text + %#llx\n",
280 table[i].addr - _text);
281 else
282 printf("\tPTR\t_text - %#llx\n",
283 _text - table[i].addr);
fd593d1 @ebiederm [PATCH] relocatable kernel: Kallsyms generate relocatable symbols
ebiederm authored
284 } else {
285 printf("\tPTR\t%#llx\n", table[i].addr);
286 }
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287 }
288 printf("\n");
289
290 output_label("kallsyms_num_syms");
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291 printf("\tPTR\t%d\n", table_cnt);
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292 printf("\n");
293
294 /* table of offset markers, that give the offset in the compressed stream
295 * every 256 symbols */
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296 markers = malloc(sizeof(unsigned int) * ((table_cnt + 255) / 256));
297 if (!markers) {
298 fprintf(stderr, "kallsyms failure: "
299 "unable to allocate required memory\n");
300 exit(EXIT_FAILURE);
301 }
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302
303 output_label("kallsyms_names");
304 off = 0;
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305 for (i = 0; i < table_cnt; i++) {
306 if ((i & 0xFF) == 0)
307 markers[i >> 8] = off;
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308
309 printf("\t.byte 0x%02x", table[i].len);
310 for (k = 0; k < table[i].len; k++)
311 printf(", 0x%02x", table[i].sym[k]);
312 printf("\n");
313
314 off += table[i].len + 1;
315 }
316 printf("\n");
317
318 output_label("kallsyms_markers");
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319 for (i = 0; i < ((table_cnt + 255) >> 8); i++)
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320 printf("\tPTR\t%d\n", markers[i]);
321 printf("\n");
322
323 free(markers);
324
325 output_label("kallsyms_token_table");
326 off = 0;
327 for (i = 0; i < 256; i++) {
328 best_idx[i] = off;
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329 expand_symbol(best_table[i], best_table_len[i], buf);
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330 printf("\t.asciz\t\"%s\"\n", buf);
331 off += strlen(buf) + 1;
332 }
333 printf("\n");
334
335 output_label("kallsyms_token_index");
336 for (i = 0; i < 256; i++)
337 printf("\t.short\t%d\n", best_idx[i]);
338 printf("\n");
339 }
340
341
342 /* table lookup compression functions */
343
344 /* count all the possible tokens in a symbol */
345 static void learn_symbol(unsigned char *symbol, int len)
346 {
347 int i;
348
349 for (i = 0; i < len - 1; i++)
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350 token_profit[ symbol[i] + (symbol[i + 1] << 8) ]++;
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351 }
352
353 /* decrease the count for all the possible tokens in a symbol */
354 static void forget_symbol(unsigned char *symbol, int len)
355 {
356 int i;
357
358 for (i = 0; i < len - 1; i++)
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359 token_profit[ symbol[i] + (symbol[i + 1] << 8) ]--;
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360 }
361
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362 /* remove all the invalid symbols from the table and do the initial token count */
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363 static void build_initial_tok_table(void)
364 {
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365 unsigned int i, pos;
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366
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367 pos = 0;
368 for (i = 0; i < table_cnt; i++) {
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369 if ( symbol_valid(&table[i]) ) {
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370 if (pos != i)
371 table[pos] = table[i];
372 learn_symbol(table[pos].sym, table[pos].len);
373 pos++;
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374 }
375 }
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376 table_cnt = pos;
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377 }
378
7c5d249 kallsyms: remove usage of memmem and _GNU_SOURCE from scripts/kallsyms.c
Paulo Marques authored
379 static void *find_token(unsigned char *str, int len, unsigned char *token)
380 {
381 int i;
382
383 for (i = 0; i < len - 1; i++) {
384 if (str[i] == token[0] && str[i+1] == token[1])
385 return &str[i];
386 }
387 return NULL;
388 }
389
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390 /* replace a given token in all the valid symbols. Use the sampled symbols
391 * to update the counts */
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392 static void compress_symbols(unsigned char *str, int idx)
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393 {
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394 unsigned int i, len, size;
395 unsigned char *p1, *p2;
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396
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397 for (i = 0; i < table_cnt; i++) {
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398
399 len = table[i].len;
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400 p1 = table[i].sym;
401
402 /* find the token on the symbol */
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403 p2 = find_token(p1, len, str);
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404 if (!p2) continue;
405
406 /* decrease the counts for this symbol's tokens */
407 forget_symbol(table[i].sym, len);
408
409 size = len;
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410
411 do {
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412 *p2 = idx;
413 p2++;
414 size -= (p2 - p1);
415 memmove(p2, p2 + 1, size);
416 p1 = p2;
417 len--;
418
419 if (size < 2) break;
420
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421 /* find the token on the symbol */
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422 p2 = find_token(p1, size, str);
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423
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424 } while (p2);
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425
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426 table[i].len = len;
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427
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428 /* increase the counts for this symbol's new tokens */
429 learn_symbol(table[i].sym, len);
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
430 }
431 }
432
433 /* search the token with the maximum profit */
b3dbb4e [PATCH] kallsyms: change compression algorithm
Paulo Marques authored
434 static int find_best_token(void)
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
435 {
b3dbb4e [PATCH] kallsyms: change compression algorithm
Paulo Marques authored
436 int i, best, bestprofit;
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
437
438 bestprofit=-10000;
b3dbb4e [PATCH] kallsyms: change compression algorithm
Paulo Marques authored
439 best = 0;
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
440
b3dbb4e [PATCH] kallsyms: change compression algorithm
Paulo Marques authored
441 for (i = 0; i < 0x10000; i++) {
442 if (token_profit[i] > bestprofit) {
443 best = i;
444 bestprofit = token_profit[i];
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
445 }
446 }
447 return best;
448 }
449
450 /* this is the core of the algorithm: calculate the "best" table */
451 static void optimize_result(void)
452 {
b3dbb4e [PATCH] kallsyms: change compression algorithm
Paulo Marques authored
453 int i, best;
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
454
455 /* using the '\0' symbol last allows compress_symbols to use standard
456 * fast string functions */
457 for (i = 255; i >= 0; i--) {
458
459 /* if this table slot is empty (it is not used by an actual
460 * original char code */
461 if (!best_table_len[i]) {
462
463 /* find the token with the breates profit value */
464 best = find_best_token();
465
466 /* place it in the "best" table */
b3dbb4e [PATCH] kallsyms: change compression algorithm
Paulo Marques authored
467 best_table_len[i] = 2;
468 best_table[i][0] = best & 0xFF;
469 best_table[i][1] = (best >> 8) & 0xFF;
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
470
471 /* replace this token in all the valid symbols */
b3dbb4e [PATCH] kallsyms: change compression algorithm
Paulo Marques authored
472 compress_symbols(best_table[i], i);
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
473 }
474 }
475 }
476
477 /* start by placing the symbols that are actually used on the table */
478 static void insert_real_symbols_in_table(void)
479 {
b3dbb4e [PATCH] kallsyms: change compression algorithm
Paulo Marques authored
480 unsigned int i, j, c;
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
481
482 memset(best_table, 0, sizeof(best_table));
483 memset(best_table_len, 0, sizeof(best_table_len));
484
b3dbb4e [PATCH] kallsyms: change compression algorithm
Paulo Marques authored
485 for (i = 0; i < table_cnt; i++) {
486 for (j = 0; j < table[i].len; j++) {
487 c = table[i].sym[j];
488 best_table[c][0]=c;
489 best_table_len[c]=1;
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
490 }
491 }
492 }
493
494 static void optimize_token_table(void)
495 {
496 build_initial_tok_table();
497
498 insert_real_symbols_in_table();
499
41f11a4 @ysat0 [PATCH] kallsyms C_SYMBOL_PREFIX support
ysat0 authored
500 /* When valid symbol is not registered, exit to error */
b3dbb4e [PATCH] kallsyms: change compression algorithm
Paulo Marques authored
501 if (!table_cnt) {
41f11a4 @ysat0 [PATCH] kallsyms C_SYMBOL_PREFIX support
ysat0 authored
502 fprintf(stderr, "No valid symbol.\n");
503 exit(1);
504 }
505
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
506 optimize_result();
507 }
508
509
b3dbb4e [PATCH] kallsyms: change compression algorithm
Paulo Marques authored
510 int main(int argc, char **argv)
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
511 {
41f11a4 @ysat0 [PATCH] kallsyms C_SYMBOL_PREFIX support
ysat0 authored
512 if (argc >= 2) {
513 int i;
514 for (i = 1; i < argc; i++) {
515 if(strcmp(argv[i], "--all-symbols") == 0)
516 all_symbols = 1;
517 else if (strncmp(argv[i], "--symbol-prefix=", 16) == 0) {
518 char *p = &argv[i][16];
519 /* skip quote */
520 if ((*p == '"' && *(p+2) == '"') || (*p == '\'' && *(p+2) == '\''))
521 p++;
522 symbol_prefix_char = *p;
523 } else
524 usage();
525 }
526 } else if (argc != 1)
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
527 usage();
528
529 read_map(stdin);
530 optimize_token_table();
531 write_src();
532
533 return 0;
534 }
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