ia64/linux-2.6.18-xen.hg

view scripts/kallsyms.c @ 562:66faefe721eb

pvSCSI backend driver

Signed-off-by: Tomonari Horikoshi <t.horikoshi@jp.fujitsu.com>
Signed-off-by: Jun Kamada <kama@jp.fujitsu.com>
author Keir Fraser <keir.fraser@citrix.com>
date Mon Jun 02 09:58:27 2008 +0100 (2008-06-02)
parents 831230e53067
children
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/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 */
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: kallsyms [--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 if (!s->sym) {
128 fprintf(stderr, "kallsyms failure: "
129 "unable to allocate required amount of memory\n");
130 exit(EXIT_FAILURE);
131 }
132 strcpy((char *)s->sym + 1, str);
133 s->sym[0] = stype;
135 return 0;
136 }
138 static int symbol_valid(struct sym_entry *s)
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",
153 /* Exclude linker generated symbols which vary between passes */
154 "_SDA_BASE_", /* ppc */
155 "_SDA2_BASE_", /* ppc */
156 NULL };
157 int i;
158 int offset = 1;
160 /* skip prefix char */
161 if (symbol_prefix_char && *(s->sym + 1) == symbol_prefix_char)
162 offset++;
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)
168 && (s->addr < _sinittext || s->addr > _einittext)
169 && (s->addr < _sextratext || s->addr > _eextratext))
170 return 0;
171 /* Corner case. Discard any symbols with the same value as
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.
176 */
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")))
180 return 0;
181 }
183 /* Exclude symbols which vary between passes. */
184 if (strstr((char *)s->sym + offset, "_compiled."))
185 return 0;
187 for (i = 0; special_symbols[i]; i++)
188 if( strcmp((char *)s->sym + offset, special_symbols[i]) == 0 )
189 return 0;
191 return 1;
192 }
194 static void read_map(FILE *in)
195 {
196 while (!feof(in)) {
197 if (table_cnt >= table_size) {
198 table_size += 10000;
199 table = realloc(table, sizeof(*table) * table_size);
200 if (!table) {
201 fprintf(stderr, "out of memory\n");
202 exit (1);
203 }
204 }
205 if (read_symbol(in, &table[table_cnt]) == 0)
206 table_cnt++;
207 }
208 }
210 static void output_label(char *label)
211 {
212 if (symbol_prefix_char)
213 printf(".globl %c%s\n", symbol_prefix_char, label);
214 else
215 printf(".globl %s\n", label);
216 printf("\tALGN\n");
217 if (symbol_prefix_char)
218 printf("%c%s:\n", symbol_prefix_char, label);
219 else
220 printf("%s:\n", label);
221 }
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;
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;
247 return total;
248 }
250 static void write_src(void)
251 {
252 unsigned int i, k, off;
253 unsigned int best_idx[256];
254 unsigned int *markers;
255 char buf[KSYM_NAME_LEN+1];
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");
266 printf(".data\n");
268 output_label("kallsyms_addresses");
269 for (i = 0; i < table_cnt; i++) {
270 printf("\tPTR\t%#llx\n", table[i].addr);
271 }
272 printf("\n");
274 output_label("kallsyms_num_syms");
275 printf("\tPTR\t%d\n", table_cnt);
276 printf("\n");
278 /* table of offset markers, that give the offset in the compressed stream
279 * every 256 symbols */
280 markers = malloc(sizeof(unsigned int) * ((table_cnt + 255) / 256));
281 if (!markers) {
282 fprintf(stderr, "kallsyms failure: "
283 "unable to allocate required memory\n");
284 exit(EXIT_FAILURE);
285 }
287 output_label("kallsyms_names");
288 off = 0;
289 for (i = 0; i < table_cnt; i++) {
290 if ((i & 0xFF) == 0)
291 markers[i >> 8] = off;
293 printf("\t.byte 0x%02x", table[i].len);
294 for (k = 0; k < table[i].len; k++)
295 printf(", 0x%02x", table[i].sym[k]);
296 printf("\n");
298 off += table[i].len + 1;
299 }
300 printf("\n");
302 output_label("kallsyms_markers");
303 for (i = 0; i < ((table_cnt + 255) >> 8); i++)
304 printf("\tPTR\t%d\n", markers[i]);
305 printf("\n");
307 free(markers);
309 output_label("kallsyms_token_table");
310 off = 0;
311 for (i = 0; i < 256; i++) {
312 best_idx[i] = off;
313 expand_symbol(best_table[i], best_table_len[i], buf);
314 printf("\t.asciz\t\"%s\"\n", buf);
315 off += strlen(buf) + 1;
316 }
317 printf("\n");
319 output_label("kallsyms_token_index");
320 for (i = 0; i < 256; i++)
321 printf("\t.short\t%d\n", best_idx[i]);
322 printf("\n");
323 }
326 /* table lookup compression functions */
328 /* count all the possible tokens in a symbol */
329 static void learn_symbol(unsigned char *symbol, int len)
330 {
331 int i;
333 for (i = 0; i < len - 1; i++)
334 token_profit[ symbol[i] + (symbol[i + 1] << 8) ]++;
335 }
337 /* decrease the count for all the possible tokens in a symbol */
338 static void forget_symbol(unsigned char *symbol, int len)
339 {
340 int i;
342 for (i = 0; i < len - 1; i++)
343 token_profit[ symbol[i] + (symbol[i + 1] << 8) ]--;
344 }
346 /* remove all the invalid symbols from the table and do the initial token count */
347 static void build_initial_tok_table(void)
348 {
349 unsigned int i, pos;
351 pos = 0;
352 for (i = 0; i < table_cnt; i++) {
353 if ( symbol_valid(&table[i]) ) {
354 if (pos != i)
355 table[pos] = table[i];
356 learn_symbol(table[pos].sym, table[pos].len);
357 pos++;
358 }
359 }
360 table_cnt = pos;
361 }
363 /* replace a given token in all the valid symbols. Use the sampled symbols
364 * to update the counts */
365 static void compress_symbols(unsigned char *str, int idx)
366 {
367 unsigned int i, len, size;
368 unsigned char *p1, *p2;
370 for (i = 0; i < table_cnt; i++) {
372 len = table[i].len;
373 p1 = table[i].sym;
375 /* find the token on the symbol */
376 p2 = memmem(p1, len, str, 2);
377 if (!p2) continue;
379 /* decrease the counts for this symbol's tokens */
380 forget_symbol(table[i].sym, len);
382 size = len;
384 do {
385 *p2 = idx;
386 p2++;
387 size -= (p2 - p1);
388 memmove(p2, p2 + 1, size);
389 p1 = p2;
390 len--;
392 if (size < 2) break;
394 /* find the token on the symbol */
395 p2 = memmem(p1, size, str, 2);
397 } while (p2);
399 table[i].len = len;
401 /* increase the counts for this symbol's new tokens */
402 learn_symbol(table[i].sym, len);
403 }
404 }
406 /* search the token with the maximum profit */
407 static int find_best_token(void)
408 {
409 int i, best, bestprofit;
411 bestprofit=-10000;
412 best = 0;
414 for (i = 0; i < 0x10000; i++) {
415 if (token_profit[i] > bestprofit) {
416 best = i;
417 bestprofit = token_profit[i];
418 }
419 }
420 return best;
421 }
423 /* this is the core of the algorithm: calculate the "best" table */
424 static void optimize_result(void)
425 {
426 int i, best;
428 /* using the '\0' symbol last allows compress_symbols to use standard
429 * fast string functions */
430 for (i = 255; i >= 0; i--) {
432 /* if this table slot is empty (it is not used by an actual
433 * original char code */
434 if (!best_table_len[i]) {
436 /* find the token with the breates profit value */
437 best = find_best_token();
439 /* place it in the "best" table */
440 best_table_len[i] = 2;
441 best_table[i][0] = best & 0xFF;
442 best_table[i][1] = (best >> 8) & 0xFF;
444 /* replace this token in all the valid symbols */
445 compress_symbols(best_table[i], i);
446 }
447 }
448 }
450 /* start by placing the symbols that are actually used on the table */
451 static void insert_real_symbols_in_table(void)
452 {
453 unsigned int i, j, c;
455 memset(best_table, 0, sizeof(best_table));
456 memset(best_table_len, 0, sizeof(best_table_len));
458 for (i = 0; i < table_cnt; i++) {
459 for (j = 0; j < table[i].len; j++) {
460 c = table[i].sym[j];
461 best_table[c][0]=c;
462 best_table_len[c]=1;
463 }
464 }
465 }
467 static void optimize_token_table(void)
468 {
469 build_initial_tok_table();
471 insert_real_symbols_in_table();
473 /* When valid symbol is not registered, exit to error */
474 if (!table_cnt) {
475 fprintf(stderr, "No valid symbol.\n");
476 exit(1);
477 }
479 optimize_result();
480 }
483 int main(int argc, char **argv)
484 {
485 if (argc >= 2) {
486 int i;
487 for (i = 1; i < argc; i++) {
488 if(strcmp(argv[i], "--all-symbols") == 0)
489 all_symbols = 1;
490 else if (strncmp(argv[i], "--symbol-prefix=", 16) == 0) {
491 char *p = &argv[i][16];
492 /* skip quote */
493 if ((*p == '"' && *(p+2) == '"') || (*p == '\'' && *(p+2) == '\''))
494 p++;
495 symbol_prefix_char = *p;
496 } else
497 usage();
498 }
499 } else if (argc != 1)
500 usage();
502 read_map(stdin);
503 optimize_token_table();
504 write_src();
506 return 0;
507 }