ia64/xen-unstable

view xen/tools/symbols.c @ 13326:037f49cd8016

Fix signedness issue in private implementation of memmem().
Signed-off-by: Alex Williamson <alex.williamson@hp.com>
author kfraser@localhost.localdomain
date Mon Jan 08 14:25:28 2007 +0000 (2007-01-08)
parents bdbfbfdfbd64
children 33242afccb32
line source
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/symbols [--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 */
27 #define _GNU_SOURCE
29 #include <stdio.h>
30 #include <stdlib.h>
31 #include <string.h>
32 #include <ctype.h>
34 #define KSYM_NAME_LEN 127
37 struct sym_entry {
38 unsigned long long addr;
39 unsigned int len;
40 unsigned char *sym;
41 };
44 static struct sym_entry *table;
45 static unsigned int table_size, table_cnt;
46 static unsigned long long _stext, _etext, _sinittext, _einittext, _sextratext, _eextratext;
47 static int all_symbols = 0;
48 static char symbol_prefix_char = '\0';
50 int token_profit[0x10000];
52 /* the table that holds the result of the compression */
53 unsigned char best_table[256][2];
54 unsigned char best_table_len[256];
57 static void usage(void)
58 {
59 fprintf(stderr, "Usage: symbols [--all-symbols] [--symbol-prefix=<prefix char>] < in.map > out.S\n");
60 exit(1);
61 }
63 /*
64 * This ignores the intensely annoying "mapping symbols" found
65 * in ARM ELF files: $a, $t and $d.
66 */
67 static inline int is_arm_mapping_symbol(const char *str)
68 {
69 return str[0] == '$' && strchr("atd", str[1])
70 && (str[2] == '\0' || str[2] == '.');
71 }
73 static int read_symbol(FILE *in, struct sym_entry *s)
74 {
75 char str[500];
76 char *sym, stype;
77 int rc;
79 rc = fscanf(in, "%llx %c %499s\n", &s->addr, &stype, str);
80 if (rc != 3) {
81 if (rc != EOF) {
82 /* skip line */
83 fgets(str, 500, in);
84 }
85 return -1;
86 }
88 sym = str;
89 /* skip prefix char */
90 if (symbol_prefix_char && str[0] == symbol_prefix_char)
91 sym++;
93 /* Ignore most absolute/undefined (?) symbols. */
94 if (strcmp(sym, "_stext") == 0)
95 _stext = s->addr;
96 else if (strcmp(sym, "_etext") == 0)
97 _etext = s->addr;
98 else if (strcmp(sym, "_sinittext") == 0)
99 _sinittext = s->addr;
100 else if (strcmp(sym, "_einittext") == 0)
101 _einittext = s->addr;
102 else if (strcmp(sym, "_sextratext") == 0)
103 _sextratext = s->addr;
104 else if (strcmp(sym, "_eextratext") == 0)
105 _eextratext = s->addr;
106 else if (toupper(stype) == 'A')
107 {
108 /* Keep these useful absolute symbols */
109 if (strcmp(sym, "__kernel_syscall_via_break") &&
110 strcmp(sym, "__kernel_syscall_via_epc") &&
111 strcmp(sym, "__kernel_sigtramp") &&
112 strcmp(sym, "__gp"))
113 return -1;
115 }
116 else if (toupper(stype) == 'U' ||
117 is_arm_mapping_symbol(sym))
118 return -1;
119 /* exclude also MIPS ELF local symbols ($L123 instead of .L123) */
120 else if (str[0] == '$')
121 return -1;
123 /* include the type field in the symbol name, so that it gets
124 * compressed together */
125 s->len = strlen(str) + 1;
126 s->sym = malloc(s->len + 1);
127 strcpy((char *)s->sym + 1, str);
128 s->sym[0] = stype;
130 return 0;
131 }
133 static int symbol_valid(struct sym_entry *s)
134 {
135 /* Symbols which vary between passes. Passes 1 and 2 must have
136 * identical symbol lists. The symbols_* symbols below are only added
137 * after pass 1, they would be included in pass 2 when --all-symbols is
138 * specified so exclude them to get a stable symbol list.
139 */
140 static char *special_symbols[] = {
141 "symbols_addresses",
142 "symbols_num_syms",
143 "symbols_names",
144 "symbols_markers",
145 "symbols_token_table",
146 "symbols_token_index",
148 /* Exclude linker generated symbols which vary between passes */
149 "_SDA_BASE_", /* ppc */
150 "_SDA2_BASE_", /* ppc */
151 NULL };
152 int i;
153 int offset = 1;
155 /* skip prefix char */
156 if (symbol_prefix_char && *(s->sym + 1) == symbol_prefix_char)
157 offset++;
159 /* if --all-symbols is not specified, then symbols outside the text
160 * and inittext sections are discarded */
161 if (!all_symbols) {
162 if ((s->addr < _stext || s->addr > _etext)
163 && (s->addr < _sinittext || s->addr > _einittext)
164 && (s->addr < _sextratext || s->addr > _eextratext))
165 return 0;
166 /* Corner case. Discard any symbols with the same value as
167 * _etext _einittext or _eextratext; they can move between pass
168 * 1 and 2 when the symbols data are added. If these symbols
169 * move then they may get dropped in pass 2, which breaks the
170 * symbols rules.
171 */
172 if ((s->addr == _etext && strcmp((char*)s->sym + offset, "_etext")) ||
173 (s->addr == _einittext && strcmp((char*)s->sym + offset, "_einittext")) ||
174 (s->addr == _eextratext && strcmp((char*)s->sym + offset, "_eextratext")))
175 return 0;
176 }
178 /* Exclude symbols which vary between passes. */
179 if (strstr((char *)s->sym + offset, "_compiled."))
180 return 0;
182 for (i = 0; special_symbols[i]; i++)
183 if( strcmp((char *)s->sym + offset, special_symbols[i]) == 0 )
184 return 0;
186 return 1;
187 }
189 static void read_map(FILE *in)
190 {
191 while (!feof(in)) {
192 if (table_cnt >= table_size) {
193 table_size += 10000;
194 table = realloc(table, sizeof(*table) * table_size);
195 if (!table) {
196 fprintf(stderr, "out of memory\n");
197 exit (1);
198 }
199 }
200 if (read_symbol(in, &table[table_cnt]) == 0)
201 table_cnt++;
202 }
203 }
205 static void output_label(char *label)
206 {
207 if (symbol_prefix_char)
208 printf(".globl %c%s\n", symbol_prefix_char, label);
209 else
210 printf(".globl %s\n", label);
211 printf("\tALGN\n");
212 if (symbol_prefix_char)
213 printf("%c%s:\n", symbol_prefix_char, label);
214 else
215 printf("%s:\n", label);
216 }
218 /* uncompress a compressed symbol. When this function is called, the best table
219 * might still be compressed itself, so the function needs to be recursive */
220 static int expand_symbol(unsigned char *data, int len, char *result)
221 {
222 int c, rlen, total=0;
224 while (len) {
225 c = *data;
226 /* if the table holds a single char that is the same as the one
227 * we are looking for, then end the search */
228 if (best_table[c][0]==c && best_table_len[c]==1) {
229 *result++ = c;
230 total++;
231 } else {
232 /* if not, recurse and expand */
233 rlen = expand_symbol(best_table[c], best_table_len[c], result);
234 total += rlen;
235 result += rlen;
236 }
237 data++;
238 len--;
239 }
240 *result=0;
242 return total;
243 }
245 static void write_src(void)
246 {
247 unsigned int i, k, off;
248 unsigned int best_idx[256];
249 unsigned int *markers;
250 char buf[KSYM_NAME_LEN+1];
252 printf("#include <asm/types.h>\n");
253 printf("#if BITS_PER_LONG == 64\n");
254 printf("#define PTR .quad\n");
255 printf("#define ALGN .align 8\n");
256 printf("#else\n");
257 printf("#define PTR .long\n");
258 printf("#define ALGN .align 4\n");
259 printf("#endif\n");
261 printf(".data\n");
263 output_label("symbols_addresses");
264 for (i = 0; i < table_cnt; i++) {
265 printf("\tPTR\t%#llx\n", table[i].addr);
266 }
267 printf("\n");
269 output_label("symbols_num_syms");
270 printf("\tPTR\t%d\n", table_cnt);
271 printf("\n");
273 /* table of offset markers, that give the offset in the compressed stream
274 * every 256 symbols */
275 markers = (unsigned int *) malloc(sizeof(unsigned int) * ((table_cnt + 255) / 256));
277 output_label("symbols_names");
278 off = 0;
279 for (i = 0; i < table_cnt; i++) {
280 if ((i & 0xFF) == 0)
281 markers[i >> 8] = off;
283 printf("\t.byte 0x%02x", table[i].len);
284 for (k = 0; k < table[i].len; k++)
285 printf(", 0x%02x", table[i].sym[k]);
286 printf("\n");
288 off += table[i].len + 1;
289 }
290 printf("\n");
292 output_label("symbols_markers");
293 for (i = 0; i < ((table_cnt + 255) >> 8); i++)
294 printf("\tPTR\t%d\n", markers[i]);
295 printf("\n");
297 free(markers);
299 output_label("symbols_token_table");
300 off = 0;
301 for (i = 0; i < 256; i++) {
302 best_idx[i] = off;
303 expand_symbol(best_table[i], best_table_len[i], buf);
304 printf("\t.asciz\t\"%s\"\n", buf);
305 off += strlen(buf) + 1;
306 }
307 printf("\n");
309 output_label("symbols_token_index");
310 for (i = 0; i < 256; i++)
311 printf("\t.short\t%d\n", best_idx[i]);
312 printf("\n");
313 }
316 /* table lookup compression functions */
318 /* count all the possible tokens in a symbol */
319 static void learn_symbol(unsigned char *symbol, int len)
320 {
321 int i;
323 for (i = 0; i < len - 1; i++)
324 token_profit[ symbol[i] + (symbol[i + 1] << 8) ]++;
325 }
327 /* decrease the count for all the possible tokens in a symbol */
328 static void forget_symbol(unsigned char *symbol, int len)
329 {
330 int i;
332 for (i = 0; i < len - 1; i++)
333 token_profit[ symbol[i] + (symbol[i + 1] << 8) ]--;
334 }
336 /* remove all the invalid symbols from the table and do the initial token count */
337 static void build_initial_tok_table(void)
338 {
339 unsigned int i, pos;
341 pos = 0;
342 for (i = 0; i < table_cnt; i++) {
343 if ( symbol_valid(&table[i]) ) {
344 if (pos != i)
345 table[pos] = table[i];
346 learn_symbol(table[pos].sym, table[pos].len);
347 pos++;
348 }
349 }
350 table_cnt = pos;
351 }
353 static void *memmem_pvt(void *h, size_t hlen, void *n, size_t nlen)
354 {
355 char *p;
356 for (p = h; (p - (char *)h) <= (long)(hlen - nlen); p++)
357 if (!memcmp(p, n, nlen)) return p;
358 return NULL;
359 }
361 /* replace a given token in all the valid symbols. Use the sampled symbols
362 * to update the counts */
363 static void compress_symbols(unsigned char *str, int idx)
364 {
365 unsigned int i, len, size;
366 unsigned char *p1, *p2;
368 for (i = 0; i < table_cnt; i++) {
370 len = table[i].len;
371 p1 = table[i].sym;
373 /* find the token on the symbol */
374 p2 = memmem_pvt(p1, len, str, 2);
375 if (!p2) continue;
377 /* decrease the counts for this symbol's tokens */
378 forget_symbol(table[i].sym, len);
380 size = len;
382 do {
383 *p2 = idx;
384 p2++;
385 size -= (p2 - p1);
386 memmove(p2, p2 + 1, size);
387 p1 = p2;
388 len--;
390 if (size < 2) break;
392 /* find the token on the symbol */
393 p2 = memmem_pvt(p1, size, str, 2);
395 } while (p2);
397 table[i].len = len;
399 /* increase the counts for this symbol's new tokens */
400 learn_symbol(table[i].sym, len);
401 }
402 }
404 /* search the token with the maximum profit */
405 static int find_best_token(void)
406 {
407 int i, best, bestprofit;
409 bestprofit=-10000;
410 best = 0;
412 for (i = 0; i < 0x10000; i++) {
413 if (token_profit[i] > bestprofit) {
414 best = i;
415 bestprofit = token_profit[i];
416 }
417 }
418 return best;
419 }
421 /* this is the core of the algorithm: calculate the "best" table */
422 static void optimize_result(void)
423 {
424 int i, best;
426 /* using the '\0' symbol last allows compress_symbols to use standard
427 * fast string functions */
428 for (i = 255; i >= 0; i--) {
430 /* if this table slot is empty (it is not used by an actual
431 * original char code */
432 if (!best_table_len[i]) {
434 /* find the token with the breates profit value */
435 best = find_best_token();
437 /* place it in the "best" table */
438 best_table_len[i] = 2;
439 best_table[i][0] = best & 0xFF;
440 best_table[i][1] = (best >> 8) & 0xFF;
442 /* replace this token in all the valid symbols */
443 compress_symbols(best_table[i], i);
444 }
445 }
446 }
448 /* start by placing the symbols that are actually used on the table */
449 static void insert_real_symbols_in_table(void)
450 {
451 unsigned int i, j, c;
453 memset(best_table, 0, sizeof(best_table));
454 memset(best_table_len, 0, sizeof(best_table_len));
456 for (i = 0; i < table_cnt; i++) {
457 for (j = 0; j < table[i].len; j++) {
458 c = table[i].sym[j];
459 best_table[c][0]=c;
460 best_table_len[c]=1;
461 }
462 }
463 }
465 static void optimize_token_table(void)
466 {
467 build_initial_tok_table();
469 insert_real_symbols_in_table();
471 /* When valid symbol is not registered, exit to error */
472 if (!table_cnt) {
473 fprintf(stderr, "No valid symbol.\n");
474 exit(1);
475 }
477 optimize_result();
478 }
481 int main(int argc, char **argv)
482 {
483 if (argc >= 2) {
484 int i;
485 for (i = 1; i < argc; i++) {
486 if(strcmp(argv[i], "--all-symbols") == 0)
487 all_symbols = 1;
488 else if (strncmp(argv[i], "--symbol-prefix=", 16) == 0) {
489 char *p = &argv[i][16];
490 /* skip quote */
491 if ((*p == '"' && *(p+2) == '"') || (*p == '\'' && *(p+2) == '\''))
492 p++;
493 symbol_prefix_char = *p;
494 } else
495 usage();
496 }
497 } else if (argc != 1)
498 usage();
500 read_map(stdin);
501 optimize_token_table();
502 write_src();
504 return 0;
505 }