sys/i386/i386/bpf_jit_machdep.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-3-Clause
   3  *
   4  * Copyright (C) 2002-2003 NetGroup, Politecnico di Torino (Italy)
   5  * Copyright (C) 2005-2017 Jung-uk Kim <jkim@FreeBSD.org>
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  *
  12  * 1. Redistributions of source code must retain the above copyright
  13  * notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  * notice, this list of conditions and the following disclaimer in the
  16  * documentation and/or other materials provided with the distribution.
  17  * 3. Neither the name of the Politecnico di Torino nor the names of its
  18  * contributors may be used to endorse or promote products derived from
  19  * this software without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  24  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  25  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  26  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  27  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  28  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  29  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  30  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  31  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  32  */
  33
  34 #include <sys/cdefs.h>
  35 __FBSDID("$FreeBSD$");
  36
  37 #ifdef _KERNEL
  38 #include "opt_bpf.h"
  39 #include <sys/param.h>
  40 #include <sys/systm.h>
  41 #include <sys/kernel.h>
  42 #include <sys/malloc.h>
  43 #include <sys/mbuf.h>
  44 #include <sys/socket.h>
  45
  46 #include <net/if.h>
  47 #else
  48 #include <stdlib.h>
  49 #include <string.h>
  50 #include <sys/mman.h>
  51 #include <sys/param.h>
  52 #endif
  53
  54 #include <sys/types.h>
  55
  56 #include <net/bpf.h>
  57 #include <net/bpf_jitter.h>
  58
  59 #include <i386/i386/bpf_jit_machdep.h>
  60
  61 /*
  62  * Emit routine to update the jump table.
  63  */
  64 static void
  65 emit_length(bpf_bin_stream *stream, __unused u_int value, u_int len)
  66 {
  67
  68         if (stream->refs != NULL)
  69                 (stream->refs)[stream->bpf_pc] += len;
  70         stream->cur_ip += len;
  71 }
  72
  73 /*
  74  * Emit routine to output the actual binary code.
  75  */
  76 static void
  77 emit_code(bpf_bin_stream *stream, u_int value, u_int len)
  78 {
  79
  80         switch (len) {
  81         case 1:
  82                 stream->ibuf[stream->cur_ip] = (u_char)value;
  83                 stream->cur_ip++;
  84                 break;
  85
  86         case 2:
  87                 *((u_short *)(void *)(stream->ibuf + stream->cur_ip)) =
  88                     (u_short)value;
  89                 stream->cur_ip += 2;
  90                 break;
  91
  92         case 4:
  93                 *((u_int *)(void *)(stream->ibuf + stream->cur_ip)) = value;
  94                 stream->cur_ip += 4;
  95                 break;
  96         }
  97
  98         return;
  99 }
 100
 101 /*
 102  * Scan the filter program and find possible optimization.
 103  */
 104 static int
 105 bpf_jit_optimize(struct bpf_insn *prog, u_int nins)
 106 {
 107         int flags;
 108         u_int i;
 109
 110         /* Do we return immediately? */
 111         if (BPF_CLASS(prog[0].code) == BPF_RET)
 112                 return (BPF_JIT_FRET);
 113
 114         for (flags = 0, i = 0; i < nins; i++) {
 115                 switch (prog[i].code) {
 116                 case BPF_LD|BPF_W|BPF_ABS:
 117                 case BPF_LD|BPF_H|BPF_ABS:
 118                 case BPF_LD|BPF_B|BPF_ABS:
 119                 case BPF_LD|BPF_W|BPF_IND:
 120                 case BPF_LD|BPF_H|BPF_IND:
 121                 case BPF_LD|BPF_B|BPF_IND:
 122                 case BPF_LDX|BPF_MSH|BPF_B:
 123                         flags |= BPF_JIT_FPKT;
 124                         break;
 125                 case BPF_LD|BPF_MEM:
 126                 case BPF_LDX|BPF_MEM:
 127                 case BPF_ST:
 128                 case BPF_STX:
 129                         flags |= BPF_JIT_FMEM;
 130                         break;
 131                 case BPF_JMP|BPF_JA:
 132                 case BPF_JMP|BPF_JGT|BPF_K:
 133                 case BPF_JMP|BPF_JGE|BPF_K:
 134                 case BPF_JMP|BPF_JEQ|BPF_K:
 135                 case BPF_JMP|BPF_JSET|BPF_K:
 136                 case BPF_JMP|BPF_JGT|BPF_X:
 137                 case BPF_JMP|BPF_JGE|BPF_X:
 138                 case BPF_JMP|BPF_JEQ|BPF_X:
 139                 case BPF_JMP|BPF_JSET|BPF_X:
 140                         flags |= BPF_JIT_FJMP;
 141                         break;
 142                 case BPF_ALU|BPF_DIV|BPF_K:
 143                 case BPF_ALU|BPF_MOD|BPF_K:
 144                         flags |= BPF_JIT_FADK;
 145                         break;
 146                 }
 147                 if (flags == BPF_JIT_FLAG_ALL)
 148                         break;
 149         }
 150
 151         return (flags);
 152 }
 153
 154 /*
 155  * Function that does the real stuff.
 156  */
 157 bpf_filter_func
 158 bpf_jit_compile(struct bpf_insn *prog, u_int nins, size_t *size)
 159 {
 160         bpf_bin_stream stream;
 161         struct bpf_insn *ins;
 162         int flags, fret, fpkt, fmem, fjmp, fadk;
 163         int save_esp;
 164         u_int i, pass;
 165
 166         /*
 167          * NOTE: Do not modify the name of this variable, as it's used by
 168          * the macros to emit code.
 169          */
 170         emit_func emitm;
 171
 172         flags = bpf_jit_optimize(prog, nins);
 173         fret = (flags & BPF_JIT_FRET) != 0;
 174         fpkt = (flags & BPF_JIT_FPKT) != 0;
 175         fmem = (flags & BPF_JIT_FMEM) != 0;
 176         fjmp = (flags & BPF_JIT_FJMP) != 0;
 177         fadk = (flags & BPF_JIT_FADK) != 0;
 178         save_esp = (fpkt || fmem || fadk);      /* Stack is used. */
 179
 180         if (fret)
 181                 nins = 1;
 182
 183         memset(&stream, 0, sizeof(stream));
 184
 185         /* Allocate the reference table for the jumps. */
 186         if (fjmp) {
 187 #ifdef _KERNEL
 188                 stream.refs = malloc((nins + 1) * sizeof(u_int), M_BPFJIT,
 189                     M_NOWAIT | M_ZERO);
 190 #else
 191                 stream.refs = calloc(nins + 1, sizeof(u_int));
 192 #endif
 193                 if (stream.refs == NULL)
 194                         return (NULL);
 195         }
 196
 197         /*
 198          * The first pass will emit the lengths of the instructions
 199          * to create the reference table.
 200          */
 201         emitm = emit_length;
 202
 203         for (pass = 0; pass < 2; pass++) {
 204                 ins = prog;
 205
 206                 /* Create the procedure header. */
 207                 if (save_esp) {
 208                         PUSH(EBP);
 209                         MOVrd(ESP, EBP);
 210                 }
 211                 if (fmem)
 212                         SUBib(BPF_MEMWORDS * sizeof(uint32_t), ESP);
 213                 if (save_esp)
 214                         PUSH(ESI);
 215                 if (fpkt) {
 216                         PUSH(EDI);
 217                         PUSH(EBX);
 218                         MOVodd(8, EBP, EBX);
 219                         MOVodd(16, EBP, EDI);
 220                 }
 221
 222                 for (i = 0; i < nins; i++) {
 223                         stream.bpf_pc++;
 224
 225                         switch (ins->code) {
 226                         default:
 227 #ifdef _KERNEL
 228                                 return (NULL);
 229 #else
 230                                 abort();
 231 #endif
 232
 233                         case BPF_RET|BPF_K:
 234                                 MOVid(ins->k, EAX);
 235                                 if (save_esp) {
 236                                         if (fpkt) {
 237                                                 POP(EBX);
 238                                                 POP(EDI);
 239                                         }
 240                                         POP(ESI);
 241                                         LEAVE();
 242                                 }
 243                                 RET();
 244                                 break;
 245
 246                         case BPF_RET|BPF_A:
 247                                 if (save_esp) {
 248                                         if (fpkt) {
 249                                                 POP(EBX);
 250                                                 POP(EDI);
 251                                         }
 252                                         POP(ESI);
 253                                         LEAVE();
 254                                 }
 255                                 RET();
 256                                 break;
 257
 258                         case BPF_LD|BPF_W|BPF_ABS:
 259                                 MOVid(ins->k, ESI);
 260                                 CMPrd(EDI, ESI);
 261                                 JAb(12);
 262                                 MOVrd(EDI, ECX);
 263                                 SUBrd(ESI, ECX);
 264                                 CMPid(sizeof(int32_t), ECX);
 265                                 JAEb(7);
 266                                 ZEROrd(EAX);
 267                                 POP(EBX);
 268                                 POP(EDI);
 269                                 POP(ESI);
 270                                 LEAVE();
 271                                 RET();
 272                                 MOVobd(EBX, ESI, EAX);
 273                                 BSWAP(EAX);
 274                                 break;
 275
 276                         case BPF_LD|BPF_H|BPF_ABS:
 277                                 ZEROrd(EAX);
 278                                 MOVid(ins->k, ESI);
 279                                 CMPrd(EDI, ESI);
 280                                 JAb(12);
 281                                 MOVrd(EDI, ECX);
 282                                 SUBrd(ESI, ECX);
 283                                 CMPid(sizeof(int16_t), ECX);
 284                                 JAEb(5);
 285                                 POP(EBX);
 286                                 POP(EDI);
 287                                 POP(ESI);
 288                                 LEAVE();
 289                                 RET();
 290                                 MOVobw(EBX, ESI, AX);
 291                                 SWAP_AX();
 292                                 break;
 293
 294                         case BPF_LD|BPF_B|BPF_ABS:
 295                                 ZEROrd(EAX);
 296                                 MOVid(ins->k, ESI);
 297                                 CMPrd(EDI, ESI);
 298                                 JBb(5);
 299                                 POP(EBX);
 300                                 POP(EDI);
 301                                 POP(ESI);
 302                                 LEAVE();
 303                                 RET();
 304                                 MOVobb(EBX, ESI, AL);
 305                                 break;
 306
 307                         case BPF_LD|BPF_W|BPF_LEN:
 308                                 if (save_esp)
 309                                         MOVodd(12, EBP, EAX);
 310                                 else {
 311                                         MOVrd(ESP, ECX);
 312                                         MOVodd(12, ECX, EAX);
 313                                 }
 314                                 break;
 315
 316                         case BPF_LDX|BPF_W|BPF_LEN:
 317                                 if (save_esp)
 318                                         MOVodd(12, EBP, EDX);
 319                                 else {
 320                                         MOVrd(ESP, ECX);
 321                                         MOVodd(12, ECX, EDX);
 322                                 }
 323                                 break;
 324
 325                         case BPF_LD|BPF_W|BPF_IND:
 326                                 CMPrd(EDI, EDX);
 327                                 JAb(27);
 328                                 MOVid(ins->k, ESI);
 329                                 MOVrd(EDI, ECX);
 330                                 SUBrd(EDX, ECX);
 331                                 CMPrd(ESI, ECX);
 332                                 JBb(14);
 333                                 ADDrd(EDX, ESI);
 334                                 MOVrd(EDI, ECX);
 335                                 SUBrd(ESI, ECX);
 336                                 CMPid(sizeof(int32_t), ECX);
 337                                 JAEb(7);
 338                                 ZEROrd(EAX);
 339                                 POP(EBX);
 340                                 POP(EDI);
 341                                 POP(ESI);
 342                                 LEAVE();
 343                                 RET();
 344                                 MOVobd(EBX, ESI, EAX);
 345                                 BSWAP(EAX);
 346                                 break;
 347
 348                         case BPF_LD|BPF_H|BPF_IND:
 349                                 ZEROrd(EAX);
 350                                 CMPrd(EDI, EDX);
 351                                 JAb(27);
 352                                 MOVid(ins->k, ESI);
 353                                 MOVrd(EDI, ECX);
 354                                 SUBrd(EDX, ECX);
 355                                 CMPrd(ESI, ECX);
 356                                 JBb(14);
 357                                 ADDrd(EDX, ESI);
 358                                 MOVrd(EDI, ECX);
 359                                 SUBrd(ESI, ECX);
 360                                 CMPid(sizeof(int16_t), ECX);
 361                                 JAEb(5);
 362                                 POP(EBX);
 363                                 POP(EDI);
 364                                 POP(ESI);
 365                                 LEAVE();
 366                                 RET();
 367                                 MOVobw(EBX, ESI, AX);
 368                                 SWAP_AX();
 369                                 break;
 370
 371                         case BPF_LD|BPF_B|BPF_IND:
 372                                 ZEROrd(EAX);
 373                                 CMPrd(EDI, EDX);
 374                                 JAEb(13);
 375                                 MOVid(ins->k, ESI);
 376                                 MOVrd(EDI, ECX);
 377                                 SUBrd(EDX, ECX);
 378                                 CMPrd(ESI, ECX);
 379                                 JAb(5);
 380                                 POP(EBX);
 381                                 POP(EDI);
 382                                 POP(ESI);
 383                                 LEAVE();
 384                                 RET();
 385                                 ADDrd(EDX, ESI);
 386                                 MOVobb(EBX, ESI, AL);
 387                                 break;
 388
 389                         case BPF_LDX|BPF_MSH|BPF_B:
 390                                 MOVid(ins->k, ESI);
 391                                 CMPrd(EDI, ESI);
 392                                 JBb(7);
 393                                 ZEROrd(EAX);
 394                                 POP(EBX);
 395                                 POP(EDI);
 396                                 POP(ESI);
 397                                 LEAVE();
 398                                 RET();
 399                                 ZEROrd(EDX);
 400                                 MOVobb(EBX, ESI, DL);
 401                                 ANDib(0x0f, DL);
 402                                 SHLib(2, EDX);
 403                                 break;
 404
 405                         case BPF_LD|BPF_IMM:
 406                                 MOVid(ins->k, EAX);
 407                                 break;
 408
 409                         case BPF_LDX|BPF_IMM:
 410                                 MOVid(ins->k, EDX);
 411                                 break;
 412
 413                         case BPF_LD|BPF_MEM:
 414                                 MOVrd(EBP, ECX);
 415                                 MOVid(((int)ins->k - BPF_MEMWORDS) *
 416                                     sizeof(uint32_t), ESI);
 417                                 MOVobd(ECX, ESI, EAX);
 418                                 break;
 419
 420                         case BPF_LDX|BPF_MEM:
 421                                 MOVrd(EBP, ECX);
 422                                 MOVid(((int)ins->k - BPF_MEMWORDS) *
 423                                     sizeof(uint32_t), ESI);
 424                                 MOVobd(ECX, ESI, EDX);
 425                                 break;
 426
 427                         case BPF_ST:
 428                                 /*
 429                                  * XXX this command and the following could
 430                                  * be optimized if the previous instruction
 431                                  * was already of this type
 432                                  */
 433                                 MOVrd(EBP, ECX);
 434                                 MOVid(((int)ins->k - BPF_MEMWORDS) *
 435                                     sizeof(uint32_t), ESI);
 436                                 MOVomd(EAX, ECX, ESI);
 437                                 break;
 438
 439                         case BPF_STX:
 440                                 MOVrd(EBP, ECX);
 441                                 MOVid(((int)ins->k - BPF_MEMWORDS) *
 442                                     sizeof(uint32_t), ESI);
 443                                 MOVomd(EDX, ECX, ESI);
 444                                 break;
 445
 446                         case BPF_JMP|BPF_JA:
 447                                 JUMP(ins->k);
 448                                 break;
 449
 450                         case BPF_JMP|BPF_JGT|BPF_K:
 451                         case BPF_JMP|BPF_JGE|BPF_K:
 452                         case BPF_JMP|BPF_JEQ|BPF_K:
 453                         case BPF_JMP|BPF_JSET|BPF_K:
 454                         case BPF_JMP|BPF_JGT|BPF_X:
 455                         case BPF_JMP|BPF_JGE|BPF_X:
 456                         case BPF_JMP|BPF_JEQ|BPF_X:
 457                         case BPF_JMP|BPF_JSET|BPF_X:
 458                                 if (ins->jt == ins->jf) {
 459                                         JUMP(ins->jt);
 460                                         break;
 461                                 }
 462                                 switch (ins->code) {
 463                                 case BPF_JMP|BPF_JGT|BPF_K:
 464                                         CMPid(ins->k, EAX);
 465                                         JCC(JA, JBE);
 466                                         break;
 467
 468                                 case BPF_JMP|BPF_JGE|BPF_K:
 469                                         CMPid(ins->k, EAX);
 470                                         JCC(JAE, JB);
 471                                         break;
 472
 473                                 case BPF_JMP|BPF_JEQ|BPF_K:
 474                                         CMPid(ins->k, EAX);
 475                                         JCC(JE, JNE);
 476                                         break;
 477
 478                                 case BPF_JMP|BPF_JSET|BPF_K:
 479                                         TESTid(ins->k, EAX);
 480                                         JCC(JNE, JE);
 481                                         break;
 482
 483                                 case BPF_JMP|BPF_JGT|BPF_X:
 484                                         CMPrd(EDX, EAX);
 485                                         JCC(JA, JBE);
 486                                         break;
 487
 488                                 case BPF_JMP|BPF_JGE|BPF_X:
 489                                         CMPrd(EDX, EAX);
 490                                         JCC(JAE, JB);
 491                                         break;
 492
 493                                 case BPF_JMP|BPF_JEQ|BPF_X:
 494                                         CMPrd(EDX, EAX);
 495                                         JCC(JE, JNE);
 496                                         break;
 497
 498                                 case BPF_JMP|BPF_JSET|BPF_X:
 499                                         TESTrd(EDX, EAX);
 500                                         JCC(JNE, JE);
 501                                         break;
 502                                 }
 503                                 break;
 504
 505                         case BPF_ALU|BPF_ADD|BPF_X:
 506                                 ADDrd(EDX, EAX);
 507                                 break;
 508
 509                         case BPF_ALU|BPF_SUB|BPF_X:
 510                                 SUBrd(EDX, EAX);
 511                                 break;
 512
 513                         case BPF_ALU|BPF_MUL|BPF_X:
 514                                 MOVrd(EDX, ECX);
 515                                 MULrd(EDX);
 516                                 MOVrd(ECX, EDX);
 517                                 break;
 518
 519                         case BPF_ALU|BPF_DIV|BPF_X:
 520                         case BPF_ALU|BPF_MOD|BPF_X:
 521                                 TESTrd(EDX, EDX);
 522                                 if (save_esp) {
 523                                         if (fpkt) {
 524                                                 JNEb(7);
 525                                                 ZEROrd(EAX);
 526                                                 POP(EBX);
 527                                                 POP(EDI);
 528                                         } else {
 529                                                 JNEb(5);
 530                                                 ZEROrd(EAX);
 531                                         }
 532                                         POP(ESI);
 533                                         LEAVE();
 534                                 } else {
 535                                         JNEb(3);
 536                                         ZEROrd(EAX);
 537                                 }
 538                                 RET();
 539                                 MOVrd(EDX, ECX);
 540                                 ZEROrd(EDX);
 541                                 DIVrd(ECX);
 542                                 if (BPF_OP(ins->code) == BPF_MOD)
 543                                         MOVrd(EDX, EAX);
 544                                 MOVrd(ECX, EDX);
 545                                 break;
 546
 547                         case BPF_ALU|BPF_AND|BPF_X:
 548                                 ANDrd(EDX, EAX);
 549                                 break;
 550
 551                         case BPF_ALU|BPF_OR|BPF_X:
 552                                 ORrd(EDX, EAX);
 553                                 break;
 554
 555                         case BPF_ALU|BPF_XOR|BPF_X:
 556                                 XORrd(EDX, EAX);
 557                                 break;
 558
 559                         case BPF_ALU|BPF_LSH|BPF_X:
 560                                 MOVrd(EDX, ECX);
 561                                 SHL_CLrb(EAX);
 562                                 break;
 563
 564                         case BPF_ALU|BPF_RSH|BPF_X:
 565                                 MOVrd(EDX, ECX);
 566                                 SHR_CLrb(EAX);
 567                                 break;
 568
 569                         case BPF_ALU|BPF_ADD|BPF_K:
 570                                 ADD_EAXi(ins->k);
 571                                 break;
 572
 573                         case BPF_ALU|BPF_SUB|BPF_K:
 574                                 SUB_EAXi(ins->k);
 575                                 break;
 576
 577                         case BPF_ALU|BPF_MUL|BPF_K:
 578                                 MOVrd(EDX, ECX);
 579                                 MOVid(ins->k, EDX);
 580                                 MULrd(EDX);
 581                                 MOVrd(ECX, EDX);
 582                                 break;
 583
 584                         case BPF_ALU|BPF_DIV|BPF_K:
 585                         case BPF_ALU|BPF_MOD|BPF_K:
 586                                 MOVrd(EDX, ECX);
 587                                 ZEROrd(EDX);
 588                                 MOVid(ins->k, ESI);
 589                                 DIVrd(ESI);
 590                                 if (BPF_OP(ins->code) == BPF_MOD)
 591                                         MOVrd(EDX, EAX);
 592                                 MOVrd(ECX, EDX);
 593                                 break;
 594
 595                         case BPF_ALU|BPF_AND|BPF_K:
 596                                 ANDid(ins->k, EAX);
 597                                 break;
 598
 599                         case BPF_ALU|BPF_OR|BPF_K:
 600                                 ORid(ins->k, EAX);
 601                                 break;
 602
 603                         case BPF_ALU|BPF_XOR|BPF_K:
 604                                 XORid(ins->k, EAX);
 605                                 break;
 606
 607                         case BPF_ALU|BPF_LSH|BPF_K:
 608                                 SHLib((ins->k) & 0xff, EAX);
 609                                 break;
 610
 611                         case BPF_ALU|BPF_RSH|BPF_K:
 612                                 SHRib((ins->k) & 0xff, EAX);
 613                                 break;
 614
 615                         case BPF_ALU|BPF_NEG:
 616                                 NEGd(EAX);
 617                                 break;
 618
 619                         case BPF_MISC|BPF_TAX:
 620                                 MOVrd(EAX, EDX);
 621                                 break;
 622
 623                         case BPF_MISC|BPF_TXA:
 624                                 MOVrd(EDX, EAX);
 625                                 break;
 626                         }
 627                         ins++;
 628                 }
 629
 630                 if (pass > 0)
 631                         continue;
 632
 633                 *size = stream.cur_ip;
 634 #ifdef _KERNEL
 635                 stream.ibuf = malloc(*size, M_BPFJIT, M_EXEC | M_NOWAIT);
 636                 if (stream.ibuf == NULL)
 637                         break;
 638 #else
 639                 stream.ibuf = mmap(NULL, *size, PROT_READ | PROT_WRITE,
 640                     MAP_ANON, -1, 0);
 641                 if (stream.ibuf == MAP_FAILED) {
 642                         stream.ibuf = NULL;
 643                         break;
 644                 }
 645 #endif
 646
 647                 /*
 648                  * Modify the reference table to contain the offsets and
 649                  * not the lengths of the instructions.
 650                  */
 651                 if (fjmp)
 652                         for (i = 1; i < nins + 1; i++)
 653                                 stream.refs[i] += stream.refs[i - 1];
 654
 655                 /* Reset the counters. */
 656                 stream.cur_ip = 0;
 657                 stream.bpf_pc = 0;
 658
 659                 /* The second pass creates the actual code. */
 660                 emitm = emit_code;
 661         }
 662
 663         /*
 664          * The reference table is needed only during compilation,
 665          * now we can free it.
 666          */
 667         if (fjmp)
 668 #ifdef _KERNEL
 669                 free(stream.refs, M_BPFJIT);
 670 #else
 671                 free(stream.refs);
 672 #endif
 673
 674 #ifndef _KERNEL
 675         if (stream.ibuf != NULL &&
 676             mprotect(stream.ibuf, *size, PROT_READ | PROT_EXEC) != 0) {
 677                 munmap(stream.ibuf, *size);
 678                 stream.ibuf = NULL;
 679         }
 680 #endif
 681
 682         return ((bpf_filter_func)(void *)stream.ibuf);
 683 }