1 /* 2 * BPF asm code parser 3 * 4 * This program is free software; you can distribute it and/or modify 5 * it under the terms of the GNU General Public License as published 6 * by the Free Software Foundation; either version 2 of the License, 7 * or (at your option) any later version. 8 * 9 * Syntax kept close to: 10 * 11 * Steven McCanne and Van Jacobson. 1993. The BSD packet filter: a new 12 * architecture for user-level packet capture. In Proceedings of the 13 * USENIX Winter 1993 Conference Proceedings on USENIX Winter 1993 14 * Conference Proceedings (USENIX'93). USENIX Association, Berkeley, 15 * CA, USA, 2-2. 16 * 17 * Copyright 2013 Daniel Borkmann <borkmann@redhat.com> 18 * Licensed under the GNU General Public License, version 2.0 (GPLv2) 19 */ 20 21 %{ 22 23 #include <stdio.h> 24 #include <string.h> 25 #include <stdint.h> 26 #include <stdlib.h> 27 #include <stdbool.h> 28 #include <unistd.h> 29 #include <errno.h> 30 #include <assert.h> 31 #include <linux/filter.h> 32 33 #include "bpf_exp.yacc.h" 34 35 enum jmp_type { JTL, JFL, JKL }; 36 37 extern FILE *yyin; 38 extern int yylineno; 39 extern int yylex(void); 40 extern void yyerror(const char *str); 41 42 extern void bpf_asm_compile(FILE *fp, bool cstyle); 43 static void bpf_set_curr_instr(uint16_t op, uint8_t jt, uint8_t jf, uint32_t k); 44 static void bpf_set_curr_label(char *label); 45 static void bpf_set_jmp_label(char *label, enum jmp_type type); 46 47 %} 48 49 %union { 50 char *label; 51 uint32_t number; 52 } 53 54 %token OP_LDB OP_LDH OP_LD OP_LDX OP_ST OP_STX OP_JMP OP_JEQ OP_JGT OP_JGE 55 %token OP_JSET OP_ADD OP_SUB OP_MUL OP_DIV OP_AND OP_OR OP_XOR OP_LSH OP_RSH 56 %token OP_RET OP_TAX OP_TXA OP_LDXB OP_MOD OP_NEG OP_JNEQ OP_JLT OP_JLE OP_LDI 57 %token OP_LDXI 58 59 %token K_PKT_LEN 60 61 %token ':' ',' '[' ']' '(' ')' 'x' 'a' '+' 'M' '*' '&' '#' '%' 62 63 %token extension number label 64 65 %type <label> label 66 %type <number> extension 67 %type <number> number 68 69 %% 70 71 prog 72 : line 73 | prog line 74 ; 75 76 line 77 : instr 78 | labelled_instr 79 ; 80 81 labelled_instr 82 : labelled instr 83 ; 84 85 instr 86 : ldb 87 | ldh 88 | ld 89 | ldi 90 | ldx 91 | ldxi 92 | st 93 | stx 94 | jmp 95 | jeq 96 | jneq 97 | jlt 98 | jle 99 | jgt 100 | jge 101 | jset 102 | add 103 | sub 104 | mul 105 | div 106 | mod 107 | neg 108 | and 109 | or 110 | xor 111 | lsh 112 | rsh 113 | ret 114 | tax 115 | txa 116 ; 117 118 labelled 119 : label ':' { bpf_set_curr_label($1); } 120 ; 121 122 ldb 123 : OP_LDB '[' 'x' '+' number ']' { 124 bpf_set_curr_instr(BPF_LD | BPF_B | BPF_IND, 0, 0, $5); } 125 | OP_LDB '[' '%' 'x' '+' number ']' { 126 bpf_set_curr_instr(BPF_LD | BPF_B | BPF_IND, 0, 0, $6); } 127 | OP_LDB '[' number ']' { 128 bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0, $3); } 129 | OP_LDB extension { 130 bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0, 131 SKF_AD_OFF + $2); } 132 ; 133 134 ldh 135 : OP_LDH '[' 'x' '+' number ']' { 136 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_IND, 0, 0, $5); } 137 | OP_LDH '[' '%' 'x' '+' number ']' { 138 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_IND, 0, 0, $6); } 139 | OP_LDH '[' number ']' { 140 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0, $3); } 141 | OP_LDH extension { 142 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0, 143 SKF_AD_OFF + $2); } 144 ; 145 146 ldi 147 : OP_LDI '#' number { 148 bpf_set_curr_instr(BPF_LD | BPF_IMM, 0, 0, $3); } 149 | OP_LDI number { 150 bpf_set_curr_instr(BPF_LD | BPF_IMM, 0, 0, $2); } 151 ; 152 153 ld 154 : OP_LD '#' number { 155 bpf_set_curr_instr(BPF_LD | BPF_IMM, 0, 0, $3); } 156 | OP_LD K_PKT_LEN { 157 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_LEN, 0, 0, 0); } 158 | OP_LD extension { 159 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0, 160 SKF_AD_OFF + $2); } 161 | OP_LD 'M' '[' number ']' { 162 bpf_set_curr_instr(BPF_LD | BPF_MEM, 0, 0, $4); } 163 | OP_LD '[' 'x' '+' number ']' { 164 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_IND, 0, 0, $5); } 165 | OP_LD '[' '%' 'x' '+' number ']' { 166 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_IND, 0, 0, $6); } 167 | OP_LD '[' number ']' { 168 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0, $3); } 169 ; 170 171 ldxi 172 : OP_LDXI '#' number { 173 bpf_set_curr_instr(BPF_LDX | BPF_IMM, 0, 0, $3); } 174 | OP_LDXI number { 175 bpf_set_curr_instr(BPF_LDX | BPF_IMM, 0, 0, $2); } 176 ; 177 178 ldx 179 : OP_LDX '#' number { 180 bpf_set_curr_instr(BPF_LDX | BPF_IMM, 0, 0, $3); } 181 | OP_LDX K_PKT_LEN { 182 bpf_set_curr_instr(BPF_LDX | BPF_W | BPF_LEN, 0, 0, 0); } 183 | OP_LDX 'M' '[' number ']' { 184 bpf_set_curr_instr(BPF_LDX | BPF_MEM, 0, 0, $4); } 185 | OP_LDXB number '*' '(' '[' number ']' '&' number ')' { 186 if ($2 != 4 || $9 != 0xf) { 187 fprintf(stderr, "ldxb offset not supported!\n"); 188 exit(1); 189 } else { 190 bpf_set_curr_instr(BPF_LDX | BPF_MSH | BPF_B, 0, 0, $6); } } 191 | OP_LDX number '*' '(' '[' number ']' '&' number ')' { 192 if ($2 != 4 || $9 != 0xf) { 193 fprintf(stderr, "ldxb offset not supported!\n"); 194 exit(1); 195 } else { 196 bpf_set_curr_instr(BPF_LDX | BPF_MSH | BPF_B, 0, 0, $6); } } 197 ; 198 199 st 200 : OP_ST 'M' '[' number ']' { 201 bpf_set_curr_instr(BPF_ST, 0, 0, $4); } 202 ; 203 204 stx 205 : OP_STX 'M' '[' number ']' { 206 bpf_set_curr_instr(BPF_STX, 0, 0, $4); } 207 ; 208 209 jmp 210 : OP_JMP label { 211 bpf_set_jmp_label($2, JKL); 212 bpf_set_curr_instr(BPF_JMP | BPF_JA, 0, 0, 0); } 213 ; 214 215 jeq 216 : OP_JEQ '#' number ',' label ',' label { 217 bpf_set_jmp_label($5, JTL); 218 bpf_set_jmp_label($7, JFL); 219 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_K, 0, 0, $3); } 220 | OP_JEQ 'x' ',' label ',' label { 221 bpf_set_jmp_label($4, JTL); 222 bpf_set_jmp_label($6, JFL); 223 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); } 224 | OP_JEQ '%' 'x' ',' label ',' label { 225 bpf_set_jmp_label($5, JTL); 226 bpf_set_jmp_label($7, JFL); 227 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); } 228 | OP_JEQ '#' number ',' label { 229 bpf_set_jmp_label($5, JTL); 230 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_K, 0, 0, $3); } 231 | OP_JEQ 'x' ',' label { 232 bpf_set_jmp_label($4, JTL); 233 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); } 234 | OP_JEQ '%' 'x' ',' label { 235 bpf_set_jmp_label($5, JTL); 236 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); } 237 ; 238 239 jneq 240 : OP_JNEQ '#' number ',' label { 241 bpf_set_jmp_label($5, JFL); 242 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_K, 0, 0, $3); } 243 | OP_JNEQ 'x' ',' label { 244 bpf_set_jmp_label($4, JFL); 245 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); } 246 | OP_JNEQ '%' 'x' ',' label { 247 bpf_set_jmp_label($5, JFL); 248 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); } 249 ; 250 251 jlt 252 : OP_JLT '#' number ',' label { 253 bpf_set_jmp_label($5, JFL); 254 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_K, 0, 0, $3); } 255 | OP_JLT 'x' ',' label { 256 bpf_set_jmp_label($4, JFL); 257 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); } 258 | OP_JLT '%' 'x' ',' label { 259 bpf_set_jmp_label($5, JFL); 260 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); } 261 ; 262 263 jle 264 : OP_JLE '#' number ',' label { 265 bpf_set_jmp_label($5, JFL); 266 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_K, 0, 0, $3); } 267 | OP_JLE 'x' ',' label { 268 bpf_set_jmp_label($4, JFL); 269 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); } 270 | OP_JLE '%' 'x' ',' label { 271 bpf_set_jmp_label($5, JFL); 272 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); } 273 ; 274 275 jgt 276 : OP_JGT '#' number ',' label ',' label { 277 bpf_set_jmp_label($5, JTL); 278 bpf_set_jmp_label($7, JFL); 279 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_K, 0, 0, $3); } 280 | OP_JGT 'x' ',' label ',' label { 281 bpf_set_jmp_label($4, JTL); 282 bpf_set_jmp_label($6, JFL); 283 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); } 284 | OP_JGT '%' 'x' ',' label ',' label { 285 bpf_set_jmp_label($5, JTL); 286 bpf_set_jmp_label($7, JFL); 287 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); } 288 | OP_JGT '#' number ',' label { 289 bpf_set_jmp_label($5, JTL); 290 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_K, 0, 0, $3); } 291 | OP_JGT 'x' ',' label { 292 bpf_set_jmp_label($4, JTL); 293 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); } 294 | OP_JGT '%' 'x' ',' label { 295 bpf_set_jmp_label($5, JTL); 296 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); } 297 ; 298 299 jge 300 : OP_JGE '#' number ',' label ',' label { 301 bpf_set_jmp_label($5, JTL); 302 bpf_set_jmp_label($7, JFL); 303 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_K, 0, 0, $3); } 304 | OP_JGE 'x' ',' label ',' label { 305 bpf_set_jmp_label($4, JTL); 306 bpf_set_jmp_label($6, JFL); 307 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); } 308 | OP_JGE '%' 'x' ',' label ',' label { 309 bpf_set_jmp_label($5, JTL); 310 bpf_set_jmp_label($7, JFL); 311 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); } 312 | OP_JGE '#' number ',' label { 313 bpf_set_jmp_label($5, JTL); 314 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_K, 0, 0, $3); } 315 | OP_JGE 'x' ',' label { 316 bpf_set_jmp_label($4, JTL); 317 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); } 318 | OP_JGE '%' 'x' ',' label { 319 bpf_set_jmp_label($5, JTL); 320 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); } 321 ; 322 323 jset 324 : OP_JSET '#' number ',' label ',' label { 325 bpf_set_jmp_label($5, JTL); 326 bpf_set_jmp_label($7, JFL); 327 bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_K, 0, 0, $3); } 328 | OP_JSET 'x' ',' label ',' label { 329 bpf_set_jmp_label($4, JTL); 330 bpf_set_jmp_label($6, JFL); 331 bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_X, 0, 0, 0); } 332 | OP_JSET '%' 'x' ',' label ',' label { 333 bpf_set_jmp_label($5, JTL); 334 bpf_set_jmp_label($7, JFL); 335 bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_X, 0, 0, 0); } 336 | OP_JSET '#' number ',' label { 337 bpf_set_jmp_label($5, JTL); 338 bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_K, 0, 0, $3); } 339 | OP_JSET 'x' ',' label { 340 bpf_set_jmp_label($4, JTL); 341 bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_X, 0, 0, 0); } 342 | OP_JSET '%' 'x' ',' label { 343 bpf_set_jmp_label($5, JTL); 344 bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_X, 0, 0, 0); } 345 ; 346 347 add 348 : OP_ADD '#' number { 349 bpf_set_curr_instr(BPF_ALU | BPF_ADD | BPF_K, 0, 0, $3); } 350 | OP_ADD 'x' { 351 bpf_set_curr_instr(BPF_ALU | BPF_ADD | BPF_X, 0, 0, 0); } 352 | OP_ADD '%' 'x' { 353 bpf_set_curr_instr(BPF_ALU | BPF_ADD | BPF_X, 0, 0, 0); } 354 ; 355 356 sub 357 : OP_SUB '#' number { 358 bpf_set_curr_instr(BPF_ALU | BPF_SUB | BPF_K, 0, 0, $3); } 359 | OP_SUB 'x' { 360 bpf_set_curr_instr(BPF_ALU | BPF_SUB | BPF_X, 0, 0, 0); } 361 | OP_SUB '%' 'x' { 362 bpf_set_curr_instr(BPF_ALU | BPF_SUB | BPF_X, 0, 0, 0); } 363 ; 364 365 mul 366 : OP_MUL '#' number { 367 bpf_set_curr_instr(BPF_ALU | BPF_MUL | BPF_K, 0, 0, $3); } 368 | OP_MUL 'x' { 369 bpf_set_curr_instr(BPF_ALU | BPF_MUL | BPF_X, 0, 0, 0); } 370 | OP_MUL '%' 'x' { 371 bpf_set_curr_instr(BPF_ALU | BPF_MUL | BPF_X, 0, 0, 0); } 372 ; 373 374 div 375 : OP_DIV '#' number { 376 bpf_set_curr_instr(BPF_ALU | BPF_DIV | BPF_K, 0, 0, $3); } 377 | OP_DIV 'x' { 378 bpf_set_curr_instr(BPF_ALU | BPF_DIV | BPF_X, 0, 0, 0); } 379 | OP_DIV '%' 'x' { 380 bpf_set_curr_instr(BPF_ALU | BPF_DIV | BPF_X, 0, 0, 0); } 381 ; 382 383 mod 384 : OP_MOD '#' number { 385 bpf_set_curr_instr(BPF_ALU | BPF_MOD | BPF_K, 0, 0, $3); } 386 | OP_MOD 'x' { 387 bpf_set_curr_instr(BPF_ALU | BPF_MOD | BPF_X, 0, 0, 0); } 388 | OP_MOD '%' 'x' { 389 bpf_set_curr_instr(BPF_ALU | BPF_MOD | BPF_X, 0, 0, 0); } 390 ; 391 392 neg 393 : OP_NEG { 394 bpf_set_curr_instr(BPF_ALU | BPF_NEG, 0, 0, 0); } 395 ; 396 397 and 398 : OP_AND '#' number { 399 bpf_set_curr_instr(BPF_ALU | BPF_AND | BPF_K, 0, 0, $3); } 400 | OP_AND 'x' { 401 bpf_set_curr_instr(BPF_ALU | BPF_AND | BPF_X, 0, 0, 0); } 402 | OP_AND '%' 'x' { 403 bpf_set_curr_instr(BPF_ALU | BPF_AND | BPF_X, 0, 0, 0); } 404 ; 405 406 or 407 : OP_OR '#' number { 408 bpf_set_curr_instr(BPF_ALU | BPF_OR | BPF_K, 0, 0, $3); } 409 | OP_OR 'x' { 410 bpf_set_curr_instr(BPF_ALU | BPF_OR | BPF_X, 0, 0, 0); } 411 | OP_OR '%' 'x' { 412 bpf_set_curr_instr(BPF_ALU | BPF_OR | BPF_X, 0, 0, 0); } 413 ; 414 415 xor 416 : OP_XOR '#' number { 417 bpf_set_curr_instr(BPF_ALU | BPF_XOR | BPF_K, 0, 0, $3); } 418 | OP_XOR 'x' { 419 bpf_set_curr_instr(BPF_ALU | BPF_XOR | BPF_X, 0, 0, 0); } 420 | OP_XOR '%' 'x' { 421 bpf_set_curr_instr(BPF_ALU | BPF_XOR | BPF_X, 0, 0, 0); } 422 ; 423 424 lsh 425 : OP_LSH '#' number { 426 bpf_set_curr_instr(BPF_ALU | BPF_LSH | BPF_K, 0, 0, $3); } 427 | OP_LSH 'x' { 428 bpf_set_curr_instr(BPF_ALU | BPF_LSH | BPF_X, 0, 0, 0); } 429 | OP_LSH '%' 'x' { 430 bpf_set_curr_instr(BPF_ALU | BPF_LSH | BPF_X, 0, 0, 0); } 431 ; 432 433 rsh 434 : OP_RSH '#' number { 435 bpf_set_curr_instr(BPF_ALU | BPF_RSH | BPF_K, 0, 0, $3); } 436 | OP_RSH 'x' { 437 bpf_set_curr_instr(BPF_ALU | BPF_RSH | BPF_X, 0, 0, 0); } 438 | OP_RSH '%' 'x' { 439 bpf_set_curr_instr(BPF_ALU | BPF_RSH | BPF_X, 0, 0, 0); } 440 ; 441 442 ret 443 : OP_RET 'a' { 444 bpf_set_curr_instr(BPF_RET | BPF_A, 0, 0, 0); } 445 | OP_RET '%' 'a' { 446 bpf_set_curr_instr(BPF_RET | BPF_A, 0, 0, 0); } 447 | OP_RET 'x' { 448 bpf_set_curr_instr(BPF_RET | BPF_X, 0, 0, 0); } 449 | OP_RET '%' 'x' { 450 bpf_set_curr_instr(BPF_RET | BPF_X, 0, 0, 0); } 451 | OP_RET '#' number { 452 bpf_set_curr_instr(BPF_RET | BPF_K, 0, 0, $3); } 453 ; 454 455 tax 456 : OP_TAX { 457 bpf_set_curr_instr(BPF_MISC | BPF_TAX, 0, 0, 0); } 458 ; 459 460 txa 461 : OP_TXA { 462 bpf_set_curr_instr(BPF_MISC | BPF_TXA, 0, 0, 0); } 463 ; 464 465 %% 466 467 static int curr_instr = 0; 468 static struct sock_filter out[BPF_MAXINSNS]; 469 static char **labels, **labels_jt, **labels_jf, **labels_k; 470 471 static void bpf_assert_max(void) 472 { 473 if (curr_instr >= BPF_MAXINSNS) { 474 fprintf(stderr, "only max %u insns allowed!\n", BPF_MAXINSNS); 475 exit(1); 476 } 477 } 478 479 static void bpf_set_curr_instr(uint16_t code, uint8_t jt, uint8_t jf, 480 uint32_t k) 481 { 482 bpf_assert_max(); 483 out[curr_instr].code = code; 484 out[curr_instr].jt = jt; 485 out[curr_instr].jf = jf; 486 out[curr_instr].k = k; 487 curr_instr++; 488 } 489 490 static void bpf_set_curr_label(char *label) 491 { 492 bpf_assert_max(); 493 labels[curr_instr] = label; 494 } 495 496 static void bpf_set_jmp_label(char *label, enum jmp_type type) 497 { 498 bpf_assert_max(); 499 switch (type) { 500 case JTL: 501 labels_jt[curr_instr] = label; 502 break; 503 case JFL: 504 labels_jf[curr_instr] = label; 505 break; 506 case JKL: 507 labels_k[curr_instr] = label; 508 break; 509 } 510 } 511 512 static int bpf_find_insns_offset(const char *label) 513 { 514 int i, max = curr_instr, ret = -ENOENT; 515 516 for (i = 0; i < max; i++) { 517 if (labels[i] && !strcmp(label, labels[i])) { 518 ret = i; 519 break; 520 } 521 } 522 523 if (ret == -ENOENT) { 524 fprintf(stderr, "no such label \'%s\'!\n", label); 525 exit(1); 526 } 527 528 return ret; 529 } 530 531 static void bpf_stage_1_insert_insns(void) 532 { 533 yyparse(); 534 } 535 536 static void bpf_reduce_k_jumps(void) 537 { 538 int i; 539 540 for (i = 0; i < curr_instr; i++) { 541 if (labels_k[i]) { 542 int off = bpf_find_insns_offset(labels_k[i]); 543 out[i].k = (uint32_t) (off - i - 1); 544 } 545 } 546 } 547 548 static uint8_t bpf_encode_jt_jf_offset(int off, int i) 549 { 550 int delta = off - i - 1; 551 552 if (delta < 0 || delta > 255) { 553 fprintf(stderr, "error: insn #%d jumps to insn #%d, " 554 "which is out of range\n", i, off); 555 exit(1); 556 } 557 return (uint8_t) delta; 558 } 559 560 static void bpf_reduce_jt_jumps(void) 561 { 562 int i; 563 564 for (i = 0; i < curr_instr; i++) { 565 if (labels_jt[i]) { 566 int off = bpf_find_insns_offset(labels_jt[i]); 567 out[i].jt = bpf_encode_jt_jf_offset(off, i); 568 } 569 } 570 } 571 572 static void bpf_reduce_jf_jumps(void) 573 { 574 int i; 575 576 for (i = 0; i < curr_instr; i++) { 577 if (labels_jf[i]) { 578 int off = bpf_find_insns_offset(labels_jf[i]); 579 out[i].jf = bpf_encode_jt_jf_offset(off, i); 580 } 581 } 582 } 583 584 static void bpf_stage_2_reduce_labels(void) 585 { 586 bpf_reduce_k_jumps(); 587 bpf_reduce_jt_jumps(); 588 bpf_reduce_jf_jumps(); 589 } 590 591 static void bpf_pretty_print_c(void) 592 { 593 int i; 594 595 for (i = 0; i < curr_instr; i++) 596 printf("{ %#04x, %2u, %2u, %#010x },\n", out[i].code, 597 out[i].jt, out[i].jf, out[i].k); 598 } 599 600 static void bpf_pretty_print(void) 601 { 602 int i; 603 604 printf("%u,", curr_instr); 605 for (i = 0; i < curr_instr; i++) 606 printf("%u %u %u %u,", out[i].code, 607 out[i].jt, out[i].jf, out[i].k); 608 printf("\n"); 609 } 610 611 static void bpf_init(void) 612 { 613 memset(out, 0, sizeof(out)); 614 615 labels = calloc(BPF_MAXINSNS, sizeof(*labels)); 616 assert(labels); 617 labels_jt = calloc(BPF_MAXINSNS, sizeof(*labels_jt)); 618 assert(labels_jt); 619 labels_jf = calloc(BPF_MAXINSNS, sizeof(*labels_jf)); 620 assert(labels_jf); 621 labels_k = calloc(BPF_MAXINSNS, sizeof(*labels_k)); 622 assert(labels_k); 623 } 624 625 static void bpf_destroy_labels(void) 626 { 627 int i; 628 629 for (i = 0; i < curr_instr; i++) { 630 free(labels_jf[i]); 631 free(labels_jt[i]); 632 free(labels_k[i]); 633 free(labels[i]); 634 } 635 } 636 637 static void bpf_destroy(void) 638 { 639 bpf_destroy_labels(); 640 free(labels_jt); 641 free(labels_jf); 642 free(labels_k); 643 free(labels); 644 } 645 646 void bpf_asm_compile(FILE *fp, bool cstyle) 647 { 648 yyin = fp; 649 650 bpf_init(); 651 bpf_stage_1_insert_insns(); 652 bpf_stage_2_reduce_labels(); 653 bpf_destroy(); 654 655 if (cstyle) 656 bpf_pretty_print_c(); 657 else 658 bpf_pretty_print(); 659 660 if (fp != stdin) 661 fclose(yyin); 662 } 663 664 void yyerror(const char *str) 665 { 666 fprintf(stderr, "error: %s at line %d\n", str, yylineno); 667 exit(1); 668 } 669