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 }
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