The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (c) 1988, 1989, 1990, 1991, 1993, 1994, 1995, 1996 |
| 3 | * The Regents of the University of California. All rights reserved. |
| 4 | * |
| 5 | * Redistribution and use in source and binary forms, with or without |
| 6 | * modification, are permitted provided that: (1) source code distributions |
| 7 | * retain the above copyright notice and this paragraph in its entirety, (2) |
| 8 | * distributions including binary code include the above copyright notice and |
| 9 | * this paragraph in its entirety in the documentation or other materials |
| 10 | * provided with the distribution, and (3) all advertising materials mentioning |
| 11 | * features or use of this software display the following acknowledgement: |
| 12 | * ``This product includes software developed by the University of California, |
| 13 | * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of |
| 14 | * the University nor the names of its contributors may be used to endorse |
| 15 | * or promote products derived from this software without specific prior |
| 16 | * written permission. |
| 17 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED |
| 18 | * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF |
| 19 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. |
| 20 | * |
| 21 | * Optimization module for tcpdump intermediate representation. |
| 22 | */ |
| 23 | #ifndef lint |
| 24 | static const char rcsid[] _U_ = |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 25 | "@(#) $Header: /tcpdump/master/libpcap/optimize.c,v 1.91 2008-01-02 04:16:46 guy Exp $ (LBL)"; |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 26 | #endif |
| 27 | |
| 28 | #ifdef HAVE_CONFIG_H |
| 29 | #include "config.h" |
| 30 | #endif |
| 31 | |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 32 | #ifdef WIN32 |
| 33 | #include <pcap-stdinc.h> |
| 34 | #else /* WIN32 */ |
| 35 | #if HAVE_INTTYPES_H |
| 36 | #include <inttypes.h> |
| 37 | #elif HAVE_STDINT_H |
| 38 | #include <stdint.h> |
| 39 | #endif |
| 40 | #ifdef HAVE_SYS_BITYPES_H |
| 41 | #include <sys/bitypes.h> |
| 42 | #endif |
| 43 | #include <sys/types.h> |
| 44 | #endif /* WIN32 */ |
| 45 | |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 46 | #include <stdio.h> |
| 47 | #include <stdlib.h> |
| 48 | #include <memory.h> |
| 49 | #include <string.h> |
| 50 | |
| 51 | #include <errno.h> |
| 52 | |
| 53 | #include "pcap-int.h" |
| 54 | |
| 55 | #include "gencode.h" |
| 56 | |
| 57 | #ifdef HAVE_OS_PROTO_H |
| 58 | #include "os-proto.h" |
| 59 | #endif |
| 60 | |
| 61 | #ifdef BDEBUG |
| 62 | extern int dflag; |
| 63 | #endif |
| 64 | |
| 65 | #if defined(MSDOS) && !defined(__DJGPP__) |
| 66 | extern int _w32_ffs (int mask); |
| 67 | #define ffs _w32_ffs |
| 68 | #endif |
| 69 | |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 70 | #if defined(WIN32) && defined (_MSC_VER) |
| 71 | int ffs(int mask); |
| 72 | #endif |
| 73 | |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 74 | /* |
| 75 | * Represents a deleted instruction. |
| 76 | */ |
| 77 | #define NOP -1 |
| 78 | |
| 79 | /* |
| 80 | * Register numbers for use-def values. |
| 81 | * 0 through BPF_MEMWORDS-1 represent the corresponding scratch memory |
| 82 | * location. A_ATOM is the accumulator and X_ATOM is the index |
| 83 | * register. |
| 84 | */ |
| 85 | #define A_ATOM BPF_MEMWORDS |
| 86 | #define X_ATOM (BPF_MEMWORDS+1) |
| 87 | |
| 88 | /* |
| 89 | * This define is used to represent *both* the accumulator and |
| 90 | * x register in use-def computations. |
| 91 | * Currently, the use-def code assumes only one definition per instruction. |
| 92 | */ |
| 93 | #define AX_ATOM N_ATOMS |
| 94 | |
| 95 | /* |
| 96 | * A flag to indicate that further optimization is needed. |
| 97 | * Iterative passes are continued until a given pass yields no |
| 98 | * branch movement. |
| 99 | */ |
| 100 | static int done; |
| 101 | |
| 102 | /* |
| 103 | * A block is marked if only if its mark equals the current mark. |
| 104 | * Rather than traverse the code array, marking each item, 'cur_mark' is |
| 105 | * incremented. This automatically makes each element unmarked. |
| 106 | */ |
| 107 | static int cur_mark; |
| 108 | #define isMarked(p) ((p)->mark == cur_mark) |
| 109 | #define unMarkAll() cur_mark += 1 |
| 110 | #define Mark(p) ((p)->mark = cur_mark) |
| 111 | |
| 112 | static void opt_init(struct block *); |
| 113 | static void opt_cleanup(void); |
| 114 | |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 115 | static void intern_blocks(struct block *); |
| 116 | |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 117 | static void find_inedges(struct block *); |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 118 | #ifdef BDEBUG |
| 119 | static void opt_dump(struct block *); |
| 120 | #endif |
| 121 | |
| 122 | static int n_blocks; |
| 123 | struct block **blocks; |
| 124 | static int n_edges; |
| 125 | struct edge **edges; |
| 126 | |
| 127 | /* |
| 128 | * A bit vector set representation of the dominators. |
| 129 | * We round up the set size to the next power of two. |
| 130 | */ |
| 131 | static int nodewords; |
| 132 | static int edgewords; |
| 133 | struct block **levels; |
| 134 | bpf_u_int32 *space; |
| 135 | #define BITS_PER_WORD (8*sizeof(bpf_u_int32)) |
| 136 | /* |
| 137 | * True if a is in uset {p} |
| 138 | */ |
| 139 | #define SET_MEMBER(p, a) \ |
| 140 | ((p)[(unsigned)(a) / BITS_PER_WORD] & (1 << ((unsigned)(a) % BITS_PER_WORD))) |
| 141 | |
| 142 | /* |
| 143 | * Add 'a' to uset p. |
| 144 | */ |
| 145 | #define SET_INSERT(p, a) \ |
| 146 | (p)[(unsigned)(a) / BITS_PER_WORD] |= (1 << ((unsigned)(a) % BITS_PER_WORD)) |
| 147 | |
| 148 | /* |
| 149 | * Delete 'a' from uset p. |
| 150 | */ |
| 151 | #define SET_DELETE(p, a) \ |
| 152 | (p)[(unsigned)(a) / BITS_PER_WORD] &= ~(1 << ((unsigned)(a) % BITS_PER_WORD)) |
| 153 | |
| 154 | /* |
| 155 | * a := a intersect b |
| 156 | */ |
| 157 | #define SET_INTERSECT(a, b, n)\ |
| 158 | {\ |
| 159 | register bpf_u_int32 *_x = a, *_y = b;\ |
| 160 | register int _n = n;\ |
| 161 | while (--_n >= 0) *_x++ &= *_y++;\ |
| 162 | } |
| 163 | |
| 164 | /* |
| 165 | * a := a - b |
| 166 | */ |
| 167 | #define SET_SUBTRACT(a, b, n)\ |
| 168 | {\ |
| 169 | register bpf_u_int32 *_x = a, *_y = b;\ |
| 170 | register int _n = n;\ |
| 171 | while (--_n >= 0) *_x++ &=~ *_y++;\ |
| 172 | } |
| 173 | |
| 174 | /* |
| 175 | * a := a union b |
| 176 | */ |
| 177 | #define SET_UNION(a, b, n)\ |
| 178 | {\ |
| 179 | register bpf_u_int32 *_x = a, *_y = b;\ |
| 180 | register int _n = n;\ |
| 181 | while (--_n >= 0) *_x++ |= *_y++;\ |
| 182 | } |
| 183 | |
| 184 | static uset all_dom_sets; |
| 185 | static uset all_closure_sets; |
| 186 | static uset all_edge_sets; |
| 187 | |
| 188 | #ifndef MAX |
| 189 | #define MAX(a,b) ((a)>(b)?(a):(b)) |
| 190 | #endif |
| 191 | |
| 192 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 193 | find_levels_r(struct block *b) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 194 | { |
| 195 | int level; |
| 196 | |
| 197 | if (isMarked(b)) |
| 198 | return; |
| 199 | |
| 200 | Mark(b); |
| 201 | b->link = 0; |
| 202 | |
| 203 | if (JT(b)) { |
| 204 | find_levels_r(JT(b)); |
| 205 | find_levels_r(JF(b)); |
| 206 | level = MAX(JT(b)->level, JF(b)->level) + 1; |
| 207 | } else |
| 208 | level = 0; |
| 209 | b->level = level; |
| 210 | b->link = levels[level]; |
| 211 | levels[level] = b; |
| 212 | } |
| 213 | |
| 214 | /* |
| 215 | * Level graph. The levels go from 0 at the leaves to |
| 216 | * N_LEVELS at the root. The levels[] array points to the |
| 217 | * first node of the level list, whose elements are linked |
| 218 | * with the 'link' field of the struct block. |
| 219 | */ |
| 220 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 221 | find_levels(struct block *root) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 222 | { |
| 223 | memset((char *)levels, 0, n_blocks * sizeof(*levels)); |
| 224 | unMarkAll(); |
| 225 | find_levels_r(root); |
| 226 | } |
| 227 | |
| 228 | /* |
| 229 | * Find dominator relationships. |
| 230 | * Assumes graph has been leveled. |
| 231 | */ |
| 232 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 233 | find_dom(struct block *root) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 234 | { |
| 235 | int i; |
| 236 | struct block *b; |
| 237 | bpf_u_int32 *x; |
| 238 | |
| 239 | /* |
| 240 | * Initialize sets to contain all nodes. |
| 241 | */ |
| 242 | x = all_dom_sets; |
| 243 | i = n_blocks * nodewords; |
| 244 | while (--i >= 0) |
| 245 | *x++ = ~0; |
| 246 | /* Root starts off empty. */ |
| 247 | for (i = nodewords; --i >= 0;) |
| 248 | root->dom[i] = 0; |
| 249 | |
| 250 | /* root->level is the highest level no found. */ |
| 251 | for (i = root->level; i >= 0; --i) { |
| 252 | for (b = levels[i]; b; b = b->link) { |
| 253 | SET_INSERT(b->dom, b->id); |
| 254 | if (JT(b) == 0) |
| 255 | continue; |
| 256 | SET_INTERSECT(JT(b)->dom, b->dom, nodewords); |
| 257 | SET_INTERSECT(JF(b)->dom, b->dom, nodewords); |
| 258 | } |
| 259 | } |
| 260 | } |
| 261 | |
| 262 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 263 | propedom(struct edge *ep) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 264 | { |
| 265 | SET_INSERT(ep->edom, ep->id); |
| 266 | if (ep->succ) { |
| 267 | SET_INTERSECT(ep->succ->et.edom, ep->edom, edgewords); |
| 268 | SET_INTERSECT(ep->succ->ef.edom, ep->edom, edgewords); |
| 269 | } |
| 270 | } |
| 271 | |
| 272 | /* |
| 273 | * Compute edge dominators. |
| 274 | * Assumes graph has been leveled and predecessors established. |
| 275 | */ |
| 276 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 277 | find_edom(struct block *root) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 278 | { |
| 279 | int i; |
| 280 | uset x; |
| 281 | struct block *b; |
| 282 | |
| 283 | x = all_edge_sets; |
| 284 | for (i = n_edges * edgewords; --i >= 0; ) |
| 285 | x[i] = ~0; |
| 286 | |
| 287 | /* root->level is the highest level no found. */ |
| 288 | memset(root->et.edom, 0, edgewords * sizeof(*(uset)0)); |
| 289 | memset(root->ef.edom, 0, edgewords * sizeof(*(uset)0)); |
| 290 | for (i = root->level; i >= 0; --i) { |
| 291 | for (b = levels[i]; b != 0; b = b->link) { |
| 292 | propedom(&b->et); |
| 293 | propedom(&b->ef); |
| 294 | } |
| 295 | } |
| 296 | } |
| 297 | |
| 298 | /* |
| 299 | * Find the backwards transitive closure of the flow graph. These sets |
| 300 | * are backwards in the sense that we find the set of nodes that reach |
| 301 | * a given node, not the set of nodes that can be reached by a node. |
| 302 | * |
| 303 | * Assumes graph has been leveled. |
| 304 | */ |
| 305 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 306 | find_closure(struct block *root) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 307 | { |
| 308 | int i; |
| 309 | struct block *b; |
| 310 | |
| 311 | /* |
| 312 | * Initialize sets to contain no nodes. |
| 313 | */ |
| 314 | memset((char *)all_closure_sets, 0, |
| 315 | n_blocks * nodewords * sizeof(*all_closure_sets)); |
| 316 | |
| 317 | /* root->level is the highest level no found. */ |
| 318 | for (i = root->level; i >= 0; --i) { |
| 319 | for (b = levels[i]; b; b = b->link) { |
| 320 | SET_INSERT(b->closure, b->id); |
| 321 | if (JT(b) == 0) |
| 322 | continue; |
| 323 | SET_UNION(JT(b)->closure, b->closure, nodewords); |
| 324 | SET_UNION(JF(b)->closure, b->closure, nodewords); |
| 325 | } |
| 326 | } |
| 327 | } |
| 328 | |
| 329 | /* |
| 330 | * Return the register number that is used by s. If A and X are both |
| 331 | * used, return AX_ATOM. If no register is used, return -1. |
| 332 | * |
| 333 | * The implementation should probably change to an array access. |
| 334 | */ |
| 335 | static int |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 336 | atomuse(struct stmt *s) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 337 | { |
| 338 | register int c = s->code; |
| 339 | |
| 340 | if (c == NOP) |
| 341 | return -1; |
| 342 | |
| 343 | switch (BPF_CLASS(c)) { |
| 344 | |
| 345 | case BPF_RET: |
| 346 | return (BPF_RVAL(c) == BPF_A) ? A_ATOM : |
| 347 | (BPF_RVAL(c) == BPF_X) ? X_ATOM : -1; |
| 348 | |
| 349 | case BPF_LD: |
| 350 | case BPF_LDX: |
| 351 | return (BPF_MODE(c) == BPF_IND) ? X_ATOM : |
| 352 | (BPF_MODE(c) == BPF_MEM) ? s->k : -1; |
| 353 | |
| 354 | case BPF_ST: |
| 355 | return A_ATOM; |
| 356 | |
| 357 | case BPF_STX: |
| 358 | return X_ATOM; |
| 359 | |
| 360 | case BPF_JMP: |
| 361 | case BPF_ALU: |
| 362 | if (BPF_SRC(c) == BPF_X) |
| 363 | return AX_ATOM; |
| 364 | return A_ATOM; |
| 365 | |
| 366 | case BPF_MISC: |
| 367 | return BPF_MISCOP(c) == BPF_TXA ? X_ATOM : A_ATOM; |
| 368 | } |
| 369 | abort(); |
| 370 | /* NOTREACHED */ |
| 371 | } |
| 372 | |
| 373 | /* |
| 374 | * Return the register number that is defined by 's'. We assume that |
| 375 | * a single stmt cannot define more than one register. If no register |
| 376 | * is defined, return -1. |
| 377 | * |
| 378 | * The implementation should probably change to an array access. |
| 379 | */ |
| 380 | static int |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 381 | atomdef(struct stmt *s) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 382 | { |
| 383 | if (s->code == NOP) |
| 384 | return -1; |
| 385 | |
| 386 | switch (BPF_CLASS(s->code)) { |
| 387 | |
| 388 | case BPF_LD: |
| 389 | case BPF_ALU: |
| 390 | return A_ATOM; |
| 391 | |
| 392 | case BPF_LDX: |
| 393 | return X_ATOM; |
| 394 | |
| 395 | case BPF_ST: |
| 396 | case BPF_STX: |
| 397 | return s->k; |
| 398 | |
| 399 | case BPF_MISC: |
| 400 | return BPF_MISCOP(s->code) == BPF_TAX ? X_ATOM : A_ATOM; |
| 401 | } |
| 402 | return -1; |
| 403 | } |
| 404 | |
| 405 | /* |
| 406 | * Compute the sets of registers used, defined, and killed by 'b'. |
| 407 | * |
| 408 | * "Used" means that a statement in 'b' uses the register before any |
| 409 | * statement in 'b' defines it, i.e. it uses the value left in |
| 410 | * that register by a predecessor block of this block. |
| 411 | * "Defined" means that a statement in 'b' defines it. |
| 412 | * "Killed" means that a statement in 'b' defines it before any |
| 413 | * statement in 'b' uses it, i.e. it kills the value left in that |
| 414 | * register by a predecessor block of this block. |
| 415 | */ |
| 416 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 417 | compute_local_ud(struct block *b) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 418 | { |
| 419 | struct slist *s; |
| 420 | atomset def = 0, use = 0, kill = 0; |
| 421 | int atom; |
| 422 | |
| 423 | for (s = b->stmts; s; s = s->next) { |
| 424 | if (s->s.code == NOP) |
| 425 | continue; |
| 426 | atom = atomuse(&s->s); |
| 427 | if (atom >= 0) { |
| 428 | if (atom == AX_ATOM) { |
| 429 | if (!ATOMELEM(def, X_ATOM)) |
| 430 | use |= ATOMMASK(X_ATOM); |
| 431 | if (!ATOMELEM(def, A_ATOM)) |
| 432 | use |= ATOMMASK(A_ATOM); |
| 433 | } |
| 434 | else if (atom < N_ATOMS) { |
| 435 | if (!ATOMELEM(def, atom)) |
| 436 | use |= ATOMMASK(atom); |
| 437 | } |
| 438 | else |
| 439 | abort(); |
| 440 | } |
| 441 | atom = atomdef(&s->s); |
| 442 | if (atom >= 0) { |
| 443 | if (!ATOMELEM(use, atom)) |
| 444 | kill |= ATOMMASK(atom); |
| 445 | def |= ATOMMASK(atom); |
| 446 | } |
| 447 | } |
| 448 | if (BPF_CLASS(b->s.code) == BPF_JMP) { |
| 449 | /* |
| 450 | * XXX - what about RET? |
| 451 | */ |
| 452 | atom = atomuse(&b->s); |
| 453 | if (atom >= 0) { |
| 454 | if (atom == AX_ATOM) { |
| 455 | if (!ATOMELEM(def, X_ATOM)) |
| 456 | use |= ATOMMASK(X_ATOM); |
| 457 | if (!ATOMELEM(def, A_ATOM)) |
| 458 | use |= ATOMMASK(A_ATOM); |
| 459 | } |
| 460 | else if (atom < N_ATOMS) { |
| 461 | if (!ATOMELEM(def, atom)) |
| 462 | use |= ATOMMASK(atom); |
| 463 | } |
| 464 | else |
| 465 | abort(); |
| 466 | } |
| 467 | } |
| 468 | |
| 469 | b->def = def; |
| 470 | b->kill = kill; |
| 471 | b->in_use = use; |
| 472 | } |
| 473 | |
| 474 | /* |
| 475 | * Assume graph is already leveled. |
| 476 | */ |
| 477 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 478 | find_ud(struct block *root) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 479 | { |
| 480 | int i, maxlevel; |
| 481 | struct block *p; |
| 482 | |
| 483 | /* |
| 484 | * root->level is the highest level no found; |
| 485 | * count down from there. |
| 486 | */ |
| 487 | maxlevel = root->level; |
| 488 | for (i = maxlevel; i >= 0; --i) |
| 489 | for (p = levels[i]; p; p = p->link) { |
| 490 | compute_local_ud(p); |
| 491 | p->out_use = 0; |
| 492 | } |
| 493 | |
| 494 | for (i = 1; i <= maxlevel; ++i) { |
| 495 | for (p = levels[i]; p; p = p->link) { |
| 496 | p->out_use |= JT(p)->in_use | JF(p)->in_use; |
| 497 | p->in_use |= p->out_use &~ p->kill; |
| 498 | } |
| 499 | } |
| 500 | } |
| 501 | |
| 502 | /* |
| 503 | * These data structures are used in a Cocke and Shwarz style |
| 504 | * value numbering scheme. Since the flowgraph is acyclic, |
| 505 | * exit values can be propagated from a node's predecessors |
| 506 | * provided it is uniquely defined. |
| 507 | */ |
| 508 | struct valnode { |
| 509 | int code; |
| 510 | int v0, v1; |
| 511 | int val; |
| 512 | struct valnode *next; |
| 513 | }; |
| 514 | |
| 515 | #define MODULUS 213 |
| 516 | static struct valnode *hashtbl[MODULUS]; |
| 517 | static int curval; |
| 518 | static int maxval; |
| 519 | |
| 520 | /* Integer constants mapped with the load immediate opcode. */ |
| 521 | #define K(i) F(BPF_LD|BPF_IMM|BPF_W, i, 0L) |
| 522 | |
| 523 | struct vmapinfo { |
| 524 | int is_const; |
| 525 | bpf_int32 const_val; |
| 526 | }; |
| 527 | |
| 528 | struct vmapinfo *vmap; |
| 529 | struct valnode *vnode_base; |
| 530 | struct valnode *next_vnode; |
| 531 | |
| 532 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 533 | init_val(void) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 534 | { |
| 535 | curval = 0; |
| 536 | next_vnode = vnode_base; |
| 537 | memset((char *)vmap, 0, maxval * sizeof(*vmap)); |
| 538 | memset((char *)hashtbl, 0, sizeof hashtbl); |
| 539 | } |
| 540 | |
| 541 | /* Because we really don't have an IR, this stuff is a little messy. */ |
| 542 | static int |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 543 | F(int code, int v0, int v1) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 544 | { |
| 545 | u_int hash; |
| 546 | int val; |
| 547 | struct valnode *p; |
| 548 | |
| 549 | hash = (u_int)code ^ (v0 << 4) ^ (v1 << 8); |
| 550 | hash %= MODULUS; |
| 551 | |
| 552 | for (p = hashtbl[hash]; p; p = p->next) |
| 553 | if (p->code == code && p->v0 == v0 && p->v1 == v1) |
| 554 | return p->val; |
| 555 | |
| 556 | val = ++curval; |
| 557 | if (BPF_MODE(code) == BPF_IMM && |
| 558 | (BPF_CLASS(code) == BPF_LD || BPF_CLASS(code) == BPF_LDX)) { |
| 559 | vmap[val].const_val = v0; |
| 560 | vmap[val].is_const = 1; |
| 561 | } |
| 562 | p = next_vnode++; |
| 563 | p->val = val; |
| 564 | p->code = code; |
| 565 | p->v0 = v0; |
| 566 | p->v1 = v1; |
| 567 | p->next = hashtbl[hash]; |
| 568 | hashtbl[hash] = p; |
| 569 | |
| 570 | return val; |
| 571 | } |
| 572 | |
| 573 | static inline void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 574 | vstore(struct stmt *s, int *valp, int newval, int alter) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 575 | { |
| 576 | if (alter && *valp == newval) |
| 577 | s->code = NOP; |
| 578 | else |
| 579 | *valp = newval; |
| 580 | } |
| 581 | |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 582 | /* |
| 583 | * Do constant-folding on binary operators. |
| 584 | * (Unary operators are handled elsewhere.) |
| 585 | */ |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 586 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 587 | fold_op(struct stmt *s, int v0, int v1) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 588 | { |
| 589 | bpf_u_int32 a, b; |
| 590 | |
| 591 | a = vmap[v0].const_val; |
| 592 | b = vmap[v1].const_val; |
| 593 | |
| 594 | switch (BPF_OP(s->code)) { |
| 595 | case BPF_ADD: |
| 596 | a += b; |
| 597 | break; |
| 598 | |
| 599 | case BPF_SUB: |
| 600 | a -= b; |
| 601 | break; |
| 602 | |
| 603 | case BPF_MUL: |
| 604 | a *= b; |
| 605 | break; |
| 606 | |
| 607 | case BPF_DIV: |
| 608 | if (b == 0) |
| 609 | bpf_error("division by zero"); |
| 610 | a /= b; |
| 611 | break; |
| 612 | |
| 613 | case BPF_AND: |
| 614 | a &= b; |
| 615 | break; |
| 616 | |
| 617 | case BPF_OR: |
| 618 | a |= b; |
| 619 | break; |
| 620 | |
| 621 | case BPF_LSH: |
| 622 | a <<= b; |
| 623 | break; |
| 624 | |
| 625 | case BPF_RSH: |
| 626 | a >>= b; |
| 627 | break; |
| 628 | |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 629 | default: |
| 630 | abort(); |
| 631 | } |
| 632 | s->k = a; |
| 633 | s->code = BPF_LD|BPF_IMM; |
| 634 | done = 0; |
| 635 | } |
| 636 | |
| 637 | static inline struct slist * |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 638 | this_op(struct slist *s) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 639 | { |
| 640 | while (s != 0 && s->s.code == NOP) |
| 641 | s = s->next; |
| 642 | return s; |
| 643 | } |
| 644 | |
| 645 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 646 | opt_not(struct block *b) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 647 | { |
| 648 | struct block *tmp = JT(b); |
| 649 | |
| 650 | JT(b) = JF(b); |
| 651 | JF(b) = tmp; |
| 652 | } |
| 653 | |
| 654 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 655 | opt_peep(struct block *b) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 656 | { |
| 657 | struct slist *s; |
| 658 | struct slist *next, *last; |
| 659 | int val; |
| 660 | |
| 661 | s = b->stmts; |
| 662 | if (s == 0) |
| 663 | return; |
| 664 | |
| 665 | last = s; |
| 666 | for (/*empty*/; /*empty*/; s = next) { |
| 667 | /* |
| 668 | * Skip over nops. |
| 669 | */ |
| 670 | s = this_op(s); |
| 671 | if (s == 0) |
| 672 | break; /* nothing left in the block */ |
| 673 | |
| 674 | /* |
| 675 | * Find the next real instruction after that one |
| 676 | * (skipping nops). |
| 677 | */ |
| 678 | next = this_op(s->next); |
| 679 | if (next == 0) |
| 680 | break; /* no next instruction */ |
| 681 | last = next; |
| 682 | |
| 683 | /* |
| 684 | * st M[k] --> st M[k] |
| 685 | * ldx M[k] tax |
| 686 | */ |
| 687 | if (s->s.code == BPF_ST && |
| 688 | next->s.code == (BPF_LDX|BPF_MEM) && |
| 689 | s->s.k == next->s.k) { |
| 690 | done = 0; |
| 691 | next->s.code = BPF_MISC|BPF_TAX; |
| 692 | } |
| 693 | /* |
| 694 | * ld #k --> ldx #k |
| 695 | * tax txa |
| 696 | */ |
| 697 | if (s->s.code == (BPF_LD|BPF_IMM) && |
| 698 | next->s.code == (BPF_MISC|BPF_TAX)) { |
| 699 | s->s.code = BPF_LDX|BPF_IMM; |
| 700 | next->s.code = BPF_MISC|BPF_TXA; |
| 701 | done = 0; |
| 702 | } |
| 703 | /* |
| 704 | * This is an ugly special case, but it happens |
| 705 | * when you say tcp[k] or udp[k] where k is a constant. |
| 706 | */ |
| 707 | if (s->s.code == (BPF_LD|BPF_IMM)) { |
| 708 | struct slist *add, *tax, *ild; |
| 709 | |
| 710 | /* |
| 711 | * Check that X isn't used on exit from this |
| 712 | * block (which the optimizer might cause). |
| 713 | * We know the code generator won't generate |
| 714 | * any local dependencies. |
| 715 | */ |
| 716 | if (ATOMELEM(b->out_use, X_ATOM)) |
| 717 | continue; |
| 718 | |
| 719 | /* |
| 720 | * Check that the instruction following the ldi |
| 721 | * is an addx, or it's an ldxms with an addx |
| 722 | * following it (with 0 or more nops between the |
| 723 | * ldxms and addx). |
| 724 | */ |
| 725 | if (next->s.code != (BPF_LDX|BPF_MSH|BPF_B)) |
| 726 | add = next; |
| 727 | else |
| 728 | add = this_op(next->next); |
| 729 | if (add == 0 || add->s.code != (BPF_ALU|BPF_ADD|BPF_X)) |
| 730 | continue; |
| 731 | |
| 732 | /* |
| 733 | * Check that a tax follows that (with 0 or more |
| 734 | * nops between them). |
| 735 | */ |
| 736 | tax = this_op(add->next); |
| 737 | if (tax == 0 || tax->s.code != (BPF_MISC|BPF_TAX)) |
| 738 | continue; |
| 739 | |
| 740 | /* |
| 741 | * Check that an ild follows that (with 0 or more |
| 742 | * nops between them). |
| 743 | */ |
| 744 | ild = this_op(tax->next); |
| 745 | if (ild == 0 || BPF_CLASS(ild->s.code) != BPF_LD || |
| 746 | BPF_MODE(ild->s.code) != BPF_IND) |
| 747 | continue; |
| 748 | /* |
| 749 | * We want to turn this sequence: |
| 750 | * |
| 751 | * (004) ldi #0x2 {s} |
| 752 | * (005) ldxms [14] {next} -- optional |
| 753 | * (006) addx {add} |
| 754 | * (007) tax {tax} |
| 755 | * (008) ild [x+0] {ild} |
| 756 | * |
| 757 | * into this sequence: |
| 758 | * |
| 759 | * (004) nop |
| 760 | * (005) ldxms [14] |
| 761 | * (006) nop |
| 762 | * (007) nop |
| 763 | * (008) ild [x+2] |
| 764 | * |
| 765 | * XXX We need to check that X is not |
| 766 | * subsequently used, because we want to change |
| 767 | * what'll be in it after this sequence. |
| 768 | * |
| 769 | * We know we can eliminate the accumulator |
| 770 | * modifications earlier in the sequence since |
| 771 | * it is defined by the last stmt of this sequence |
| 772 | * (i.e., the last statement of the sequence loads |
| 773 | * a value into the accumulator, so we can eliminate |
| 774 | * earlier operations on the accumulator). |
| 775 | */ |
| 776 | ild->s.k += s->s.k; |
| 777 | s->s.code = NOP; |
| 778 | add->s.code = NOP; |
| 779 | tax->s.code = NOP; |
| 780 | done = 0; |
| 781 | } |
| 782 | } |
| 783 | /* |
| 784 | * If the comparison at the end of a block is an equality |
| 785 | * comparison against a constant, and nobody uses the value |
| 786 | * we leave in the A register at the end of a block, and |
| 787 | * the operation preceding the comparison is an arithmetic |
| 788 | * operation, we can sometime optimize it away. |
| 789 | */ |
| 790 | if (b->s.code == (BPF_JMP|BPF_JEQ|BPF_K) && |
| 791 | !ATOMELEM(b->out_use, A_ATOM)) { |
| 792 | /* |
| 793 | * We can optimize away certain subtractions of the |
| 794 | * X register. |
| 795 | */ |
| 796 | if (last->s.code == (BPF_ALU|BPF_SUB|BPF_X)) { |
| 797 | val = b->val[X_ATOM]; |
| 798 | if (vmap[val].is_const) { |
| 799 | /* |
| 800 | * If we have a subtract to do a comparison, |
| 801 | * and the X register is a known constant, |
| 802 | * we can merge this value into the |
| 803 | * comparison: |
| 804 | * |
| 805 | * sub x -> nop |
| 806 | * jeq #y jeq #(x+y) |
| 807 | */ |
| 808 | b->s.k += vmap[val].const_val; |
| 809 | last->s.code = NOP; |
| 810 | done = 0; |
| 811 | } else if (b->s.k == 0) { |
| 812 | /* |
| 813 | * If the X register isn't a constant, |
| 814 | * and the comparison in the test is |
| 815 | * against 0, we can compare with the |
| 816 | * X register, instead: |
| 817 | * |
| 818 | * sub x -> nop |
| 819 | * jeq #0 jeq x |
| 820 | */ |
| 821 | last->s.code = NOP; |
| 822 | b->s.code = BPF_JMP|BPF_JEQ|BPF_X; |
| 823 | done = 0; |
| 824 | } |
| 825 | } |
| 826 | /* |
| 827 | * Likewise, a constant subtract can be simplified: |
| 828 | * |
| 829 | * sub #x -> nop |
| 830 | * jeq #y -> jeq #(x+y) |
| 831 | */ |
| 832 | else if (last->s.code == (BPF_ALU|BPF_SUB|BPF_K)) { |
| 833 | last->s.code = NOP; |
| 834 | b->s.k += last->s.k; |
| 835 | done = 0; |
| 836 | } |
| 837 | /* |
| 838 | * And, similarly, a constant AND can be simplified |
| 839 | * if we're testing against 0, i.e.: |
| 840 | * |
| 841 | * and #k nop |
| 842 | * jeq #0 -> jset #k |
| 843 | */ |
| 844 | else if (last->s.code == (BPF_ALU|BPF_AND|BPF_K) && |
| 845 | b->s.k == 0) { |
| 846 | b->s.k = last->s.k; |
| 847 | b->s.code = BPF_JMP|BPF_K|BPF_JSET; |
| 848 | last->s.code = NOP; |
| 849 | done = 0; |
| 850 | opt_not(b); |
| 851 | } |
| 852 | } |
| 853 | /* |
| 854 | * jset #0 -> never |
| 855 | * jset #ffffffff -> always |
| 856 | */ |
| 857 | if (b->s.code == (BPF_JMP|BPF_K|BPF_JSET)) { |
| 858 | if (b->s.k == 0) |
| 859 | JT(b) = JF(b); |
| 860 | if (b->s.k == 0xffffffff) |
| 861 | JF(b) = JT(b); |
| 862 | } |
| 863 | /* |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 864 | * If we're comparing against the index register, and the index |
| 865 | * register is a known constant, we can just compare against that |
| 866 | * constant. |
| 867 | */ |
| 868 | val = b->val[X_ATOM]; |
| 869 | if (vmap[val].is_const && BPF_SRC(b->s.code) == BPF_X) { |
| 870 | bpf_int32 v = vmap[val].const_val; |
| 871 | b->s.code &= ~BPF_X; |
| 872 | b->s.k = v; |
| 873 | } |
| 874 | /* |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 875 | * If the accumulator is a known constant, we can compute the |
| 876 | * comparison result. |
| 877 | */ |
| 878 | val = b->val[A_ATOM]; |
| 879 | if (vmap[val].is_const && BPF_SRC(b->s.code) == BPF_K) { |
| 880 | bpf_int32 v = vmap[val].const_val; |
| 881 | switch (BPF_OP(b->s.code)) { |
| 882 | |
| 883 | case BPF_JEQ: |
| 884 | v = v == b->s.k; |
| 885 | break; |
| 886 | |
| 887 | case BPF_JGT: |
| 888 | v = (unsigned)v > b->s.k; |
| 889 | break; |
| 890 | |
| 891 | case BPF_JGE: |
| 892 | v = (unsigned)v >= b->s.k; |
| 893 | break; |
| 894 | |
| 895 | case BPF_JSET: |
| 896 | v &= b->s.k; |
| 897 | break; |
| 898 | |
| 899 | default: |
| 900 | abort(); |
| 901 | } |
| 902 | if (JF(b) != JT(b)) |
| 903 | done = 0; |
| 904 | if (v) |
| 905 | JF(b) = JT(b); |
| 906 | else |
| 907 | JT(b) = JF(b); |
| 908 | } |
| 909 | } |
| 910 | |
| 911 | /* |
| 912 | * Compute the symbolic value of expression of 's', and update |
| 913 | * anything it defines in the value table 'val'. If 'alter' is true, |
| 914 | * do various optimizations. This code would be cleaner if symbolic |
| 915 | * evaluation and code transformations weren't folded together. |
| 916 | */ |
| 917 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 918 | opt_stmt(struct stmt *s, int val[], int alter) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 919 | { |
| 920 | int op; |
| 921 | int v; |
| 922 | |
| 923 | switch (s->code) { |
| 924 | |
| 925 | case BPF_LD|BPF_ABS|BPF_W: |
| 926 | case BPF_LD|BPF_ABS|BPF_H: |
| 927 | case BPF_LD|BPF_ABS|BPF_B: |
| 928 | v = F(s->code, s->k, 0L); |
| 929 | vstore(s, &val[A_ATOM], v, alter); |
| 930 | break; |
| 931 | |
| 932 | case BPF_LD|BPF_IND|BPF_W: |
| 933 | case BPF_LD|BPF_IND|BPF_H: |
| 934 | case BPF_LD|BPF_IND|BPF_B: |
| 935 | v = val[X_ATOM]; |
| 936 | if (alter && vmap[v].is_const) { |
| 937 | s->code = BPF_LD|BPF_ABS|BPF_SIZE(s->code); |
| 938 | s->k += vmap[v].const_val; |
| 939 | v = F(s->code, s->k, 0L); |
| 940 | done = 0; |
| 941 | } |
| 942 | else |
| 943 | v = F(s->code, s->k, v); |
| 944 | vstore(s, &val[A_ATOM], v, alter); |
| 945 | break; |
| 946 | |
| 947 | case BPF_LD|BPF_LEN: |
| 948 | v = F(s->code, 0L, 0L); |
| 949 | vstore(s, &val[A_ATOM], v, alter); |
| 950 | break; |
| 951 | |
| 952 | case BPF_LD|BPF_IMM: |
| 953 | v = K(s->k); |
| 954 | vstore(s, &val[A_ATOM], v, alter); |
| 955 | break; |
| 956 | |
| 957 | case BPF_LDX|BPF_IMM: |
| 958 | v = K(s->k); |
| 959 | vstore(s, &val[X_ATOM], v, alter); |
| 960 | break; |
| 961 | |
| 962 | case BPF_LDX|BPF_MSH|BPF_B: |
| 963 | v = F(s->code, s->k, 0L); |
| 964 | vstore(s, &val[X_ATOM], v, alter); |
| 965 | break; |
| 966 | |
| 967 | case BPF_ALU|BPF_NEG: |
| 968 | if (alter && vmap[val[A_ATOM]].is_const) { |
| 969 | s->code = BPF_LD|BPF_IMM; |
| 970 | s->k = -vmap[val[A_ATOM]].const_val; |
| 971 | val[A_ATOM] = K(s->k); |
| 972 | } |
| 973 | else |
| 974 | val[A_ATOM] = F(s->code, val[A_ATOM], 0L); |
| 975 | break; |
| 976 | |
| 977 | case BPF_ALU|BPF_ADD|BPF_K: |
| 978 | case BPF_ALU|BPF_SUB|BPF_K: |
| 979 | case BPF_ALU|BPF_MUL|BPF_K: |
| 980 | case BPF_ALU|BPF_DIV|BPF_K: |
| 981 | case BPF_ALU|BPF_AND|BPF_K: |
| 982 | case BPF_ALU|BPF_OR|BPF_K: |
| 983 | case BPF_ALU|BPF_LSH|BPF_K: |
| 984 | case BPF_ALU|BPF_RSH|BPF_K: |
| 985 | op = BPF_OP(s->code); |
| 986 | if (alter) { |
| 987 | if (s->k == 0) { |
| 988 | /* don't optimize away "sub #0" |
| 989 | * as it may be needed later to |
| 990 | * fixup the generated math code */ |
| 991 | if (op == BPF_ADD || |
| 992 | op == BPF_LSH || op == BPF_RSH || |
| 993 | op == BPF_OR) { |
| 994 | s->code = NOP; |
| 995 | break; |
| 996 | } |
| 997 | if (op == BPF_MUL || op == BPF_AND) { |
| 998 | s->code = BPF_LD|BPF_IMM; |
| 999 | val[A_ATOM] = K(s->k); |
| 1000 | break; |
| 1001 | } |
| 1002 | } |
| 1003 | if (vmap[val[A_ATOM]].is_const) { |
| 1004 | fold_op(s, val[A_ATOM], K(s->k)); |
| 1005 | val[A_ATOM] = K(s->k); |
| 1006 | break; |
| 1007 | } |
| 1008 | } |
| 1009 | val[A_ATOM] = F(s->code, val[A_ATOM], K(s->k)); |
| 1010 | break; |
| 1011 | |
| 1012 | case BPF_ALU|BPF_ADD|BPF_X: |
| 1013 | case BPF_ALU|BPF_SUB|BPF_X: |
| 1014 | case BPF_ALU|BPF_MUL|BPF_X: |
| 1015 | case BPF_ALU|BPF_DIV|BPF_X: |
| 1016 | case BPF_ALU|BPF_AND|BPF_X: |
| 1017 | case BPF_ALU|BPF_OR|BPF_X: |
| 1018 | case BPF_ALU|BPF_LSH|BPF_X: |
| 1019 | case BPF_ALU|BPF_RSH|BPF_X: |
| 1020 | op = BPF_OP(s->code); |
| 1021 | if (alter && vmap[val[X_ATOM]].is_const) { |
| 1022 | if (vmap[val[A_ATOM]].is_const) { |
| 1023 | fold_op(s, val[A_ATOM], val[X_ATOM]); |
| 1024 | val[A_ATOM] = K(s->k); |
| 1025 | } |
| 1026 | else { |
| 1027 | s->code = BPF_ALU|BPF_K|op; |
| 1028 | s->k = vmap[val[X_ATOM]].const_val; |
| 1029 | done = 0; |
| 1030 | val[A_ATOM] = |
| 1031 | F(s->code, val[A_ATOM], K(s->k)); |
| 1032 | } |
| 1033 | break; |
| 1034 | } |
| 1035 | /* |
| 1036 | * Check if we're doing something to an accumulator |
| 1037 | * that is 0, and simplify. This may not seem like |
| 1038 | * much of a simplification but it could open up further |
| 1039 | * optimizations. |
| 1040 | * XXX We could also check for mul by 1, etc. |
| 1041 | */ |
| 1042 | if (alter && vmap[val[A_ATOM]].is_const |
| 1043 | && vmap[val[A_ATOM]].const_val == 0) { |
| 1044 | if (op == BPF_ADD || op == BPF_OR) { |
| 1045 | s->code = BPF_MISC|BPF_TXA; |
| 1046 | vstore(s, &val[A_ATOM], val[X_ATOM], alter); |
| 1047 | break; |
| 1048 | } |
| 1049 | else if (op == BPF_MUL || op == BPF_DIV || |
| 1050 | op == BPF_AND || op == BPF_LSH || op == BPF_RSH) { |
| 1051 | s->code = BPF_LD|BPF_IMM; |
| 1052 | s->k = 0; |
| 1053 | vstore(s, &val[A_ATOM], K(s->k), alter); |
| 1054 | break; |
| 1055 | } |
| 1056 | else if (op == BPF_NEG) { |
| 1057 | s->code = NOP; |
| 1058 | break; |
| 1059 | } |
| 1060 | } |
| 1061 | val[A_ATOM] = F(s->code, val[A_ATOM], val[X_ATOM]); |
| 1062 | break; |
| 1063 | |
| 1064 | case BPF_MISC|BPF_TXA: |
| 1065 | vstore(s, &val[A_ATOM], val[X_ATOM], alter); |
| 1066 | break; |
| 1067 | |
| 1068 | case BPF_LD|BPF_MEM: |
| 1069 | v = val[s->k]; |
| 1070 | if (alter && vmap[v].is_const) { |
| 1071 | s->code = BPF_LD|BPF_IMM; |
| 1072 | s->k = vmap[v].const_val; |
| 1073 | done = 0; |
| 1074 | } |
| 1075 | vstore(s, &val[A_ATOM], v, alter); |
| 1076 | break; |
| 1077 | |
| 1078 | case BPF_MISC|BPF_TAX: |
| 1079 | vstore(s, &val[X_ATOM], val[A_ATOM], alter); |
| 1080 | break; |
| 1081 | |
| 1082 | case BPF_LDX|BPF_MEM: |
| 1083 | v = val[s->k]; |
| 1084 | if (alter && vmap[v].is_const) { |
| 1085 | s->code = BPF_LDX|BPF_IMM; |
| 1086 | s->k = vmap[v].const_val; |
| 1087 | done = 0; |
| 1088 | } |
| 1089 | vstore(s, &val[X_ATOM], v, alter); |
| 1090 | break; |
| 1091 | |
| 1092 | case BPF_ST: |
| 1093 | vstore(s, &val[s->k], val[A_ATOM], alter); |
| 1094 | break; |
| 1095 | |
| 1096 | case BPF_STX: |
| 1097 | vstore(s, &val[s->k], val[X_ATOM], alter); |
| 1098 | break; |
| 1099 | } |
| 1100 | } |
| 1101 | |
| 1102 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1103 | deadstmt(register struct stmt *s, register struct stmt *last[]) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1104 | { |
| 1105 | register int atom; |
| 1106 | |
| 1107 | atom = atomuse(s); |
| 1108 | if (atom >= 0) { |
| 1109 | if (atom == AX_ATOM) { |
| 1110 | last[X_ATOM] = 0; |
| 1111 | last[A_ATOM] = 0; |
| 1112 | } |
| 1113 | else |
| 1114 | last[atom] = 0; |
| 1115 | } |
| 1116 | atom = atomdef(s); |
| 1117 | if (atom >= 0) { |
| 1118 | if (last[atom]) { |
| 1119 | done = 0; |
| 1120 | last[atom]->code = NOP; |
| 1121 | } |
| 1122 | last[atom] = s; |
| 1123 | } |
| 1124 | } |
| 1125 | |
| 1126 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1127 | opt_deadstores(register struct block *b) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1128 | { |
| 1129 | register struct slist *s; |
| 1130 | register int atom; |
| 1131 | struct stmt *last[N_ATOMS]; |
| 1132 | |
| 1133 | memset((char *)last, 0, sizeof last); |
| 1134 | |
| 1135 | for (s = b->stmts; s != 0; s = s->next) |
| 1136 | deadstmt(&s->s, last); |
| 1137 | deadstmt(&b->s, last); |
| 1138 | |
| 1139 | for (atom = 0; atom < N_ATOMS; ++atom) |
| 1140 | if (last[atom] && !ATOMELEM(b->out_use, atom)) { |
| 1141 | last[atom]->code = NOP; |
| 1142 | done = 0; |
| 1143 | } |
| 1144 | } |
| 1145 | |
| 1146 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1147 | opt_blk(struct block *b, int do_stmts) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1148 | { |
| 1149 | struct slist *s; |
| 1150 | struct edge *p; |
| 1151 | int i; |
| 1152 | bpf_int32 aval, xval; |
| 1153 | |
| 1154 | #if 0 |
| 1155 | for (s = b->stmts; s && s->next; s = s->next) |
| 1156 | if (BPF_CLASS(s->s.code) == BPF_JMP) { |
| 1157 | do_stmts = 0; |
| 1158 | break; |
| 1159 | } |
| 1160 | #endif |
| 1161 | |
| 1162 | /* |
| 1163 | * Initialize the atom values. |
| 1164 | */ |
| 1165 | p = b->in_edges; |
| 1166 | if (p == 0) { |
| 1167 | /* |
| 1168 | * We have no predecessors, so everything is undefined |
| 1169 | * upon entry to this block. |
| 1170 | */ |
| 1171 | memset((char *)b->val, 0, sizeof(b->val)); |
| 1172 | } else { |
| 1173 | /* |
| 1174 | * Inherit values from our predecessors. |
| 1175 | * |
| 1176 | * First, get the values from the predecessor along the |
| 1177 | * first edge leading to this node. |
| 1178 | */ |
| 1179 | memcpy((char *)b->val, (char *)p->pred->val, sizeof(b->val)); |
| 1180 | /* |
| 1181 | * Now look at all the other nodes leading to this node. |
| 1182 | * If, for the predecessor along that edge, a register |
| 1183 | * has a different value from the one we have (i.e., |
| 1184 | * control paths are merging, and the merging paths |
| 1185 | * assign different values to that register), give the |
| 1186 | * register the undefined value of 0. |
| 1187 | */ |
| 1188 | while ((p = p->next) != NULL) { |
| 1189 | for (i = 0; i < N_ATOMS; ++i) |
| 1190 | if (b->val[i] != p->pred->val[i]) |
| 1191 | b->val[i] = 0; |
| 1192 | } |
| 1193 | } |
| 1194 | aval = b->val[A_ATOM]; |
| 1195 | xval = b->val[X_ATOM]; |
| 1196 | for (s = b->stmts; s; s = s->next) |
| 1197 | opt_stmt(&s->s, b->val, do_stmts); |
| 1198 | |
| 1199 | /* |
| 1200 | * This is a special case: if we don't use anything from this |
| 1201 | * block, and we load the accumulator or index register with a |
| 1202 | * value that is already there, or if this block is a return, |
| 1203 | * eliminate all the statements. |
| 1204 | * |
| 1205 | * XXX - what if it does a store? |
| 1206 | * |
| 1207 | * XXX - why does it matter whether we use anything from this |
| 1208 | * block? If the accumulator or index register doesn't change |
| 1209 | * its value, isn't that OK even if we use that value? |
| 1210 | * |
| 1211 | * XXX - if we load the accumulator with a different value, |
| 1212 | * and the block ends with a conditional branch, we obviously |
| 1213 | * can't eliminate it, as the branch depends on that value. |
| 1214 | * For the index register, the conditional branch only depends |
| 1215 | * on the index register value if the test is against the index |
| 1216 | * register value rather than a constant; if nothing uses the |
| 1217 | * value we put into the index register, and we're not testing |
| 1218 | * against the index register's value, and there aren't any |
| 1219 | * other problems that would keep us from eliminating this |
| 1220 | * block, can we eliminate it? |
| 1221 | */ |
| 1222 | if (do_stmts && |
| 1223 | ((b->out_use == 0 && aval != 0 && b->val[A_ATOM] == aval && |
| 1224 | xval != 0 && b->val[X_ATOM] == xval) || |
| 1225 | BPF_CLASS(b->s.code) == BPF_RET)) { |
| 1226 | if (b->stmts != 0) { |
| 1227 | b->stmts = 0; |
| 1228 | done = 0; |
| 1229 | } |
| 1230 | } else { |
| 1231 | opt_peep(b); |
| 1232 | opt_deadstores(b); |
| 1233 | } |
| 1234 | /* |
| 1235 | * Set up values for branch optimizer. |
| 1236 | */ |
| 1237 | if (BPF_SRC(b->s.code) == BPF_K) |
| 1238 | b->oval = K(b->s.k); |
| 1239 | else |
| 1240 | b->oval = b->val[X_ATOM]; |
| 1241 | b->et.code = b->s.code; |
| 1242 | b->ef.code = -b->s.code; |
| 1243 | } |
| 1244 | |
| 1245 | /* |
| 1246 | * Return true if any register that is used on exit from 'succ', has |
| 1247 | * an exit value that is different from the corresponding exit value |
| 1248 | * from 'b'. |
| 1249 | */ |
| 1250 | static int |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1251 | use_conflict(struct block *b, struct block *succ) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1252 | { |
| 1253 | int atom; |
| 1254 | atomset use = succ->out_use; |
| 1255 | |
| 1256 | if (use == 0) |
| 1257 | return 0; |
| 1258 | |
| 1259 | for (atom = 0; atom < N_ATOMS; ++atom) |
| 1260 | if (ATOMELEM(use, atom)) |
| 1261 | if (b->val[atom] != succ->val[atom]) |
| 1262 | return 1; |
| 1263 | return 0; |
| 1264 | } |
| 1265 | |
| 1266 | static struct block * |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1267 | fold_edge(struct block *child, struct edge *ep) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1268 | { |
| 1269 | int sense; |
| 1270 | int aval0, aval1, oval0, oval1; |
| 1271 | int code = ep->code; |
| 1272 | |
| 1273 | if (code < 0) { |
| 1274 | code = -code; |
| 1275 | sense = 0; |
| 1276 | } else |
| 1277 | sense = 1; |
| 1278 | |
| 1279 | if (child->s.code != code) |
| 1280 | return 0; |
| 1281 | |
| 1282 | aval0 = child->val[A_ATOM]; |
| 1283 | oval0 = child->oval; |
| 1284 | aval1 = ep->pred->val[A_ATOM]; |
| 1285 | oval1 = ep->pred->oval; |
| 1286 | |
| 1287 | if (aval0 != aval1) |
| 1288 | return 0; |
| 1289 | |
| 1290 | if (oval0 == oval1) |
| 1291 | /* |
| 1292 | * The operands of the branch instructions are |
| 1293 | * identical, so the result is true if a true |
| 1294 | * branch was taken to get here, otherwise false. |
| 1295 | */ |
| 1296 | return sense ? JT(child) : JF(child); |
| 1297 | |
| 1298 | if (sense && code == (BPF_JMP|BPF_JEQ|BPF_K)) |
| 1299 | /* |
| 1300 | * At this point, we only know the comparison if we |
| 1301 | * came down the true branch, and it was an equality |
| 1302 | * comparison with a constant. |
| 1303 | * |
| 1304 | * I.e., if we came down the true branch, and the branch |
| 1305 | * was an equality comparison with a constant, we know the |
| 1306 | * accumulator contains that constant. If we came down |
| 1307 | * the false branch, or the comparison wasn't with a |
| 1308 | * constant, we don't know what was in the accumulator. |
| 1309 | * |
| 1310 | * We rely on the fact that distinct constants have distinct |
| 1311 | * value numbers. |
| 1312 | */ |
| 1313 | return JF(child); |
| 1314 | |
| 1315 | return 0; |
| 1316 | } |
| 1317 | |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1318 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1319 | opt_j(struct edge *ep) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1320 | { |
| 1321 | register int i, k; |
| 1322 | register struct block *target; |
| 1323 | |
| 1324 | if (JT(ep->succ) == 0) |
| 1325 | return; |
| 1326 | |
| 1327 | if (JT(ep->succ) == JF(ep->succ)) { |
| 1328 | /* |
| 1329 | * Common branch targets can be eliminated, provided |
| 1330 | * there is no data dependency. |
| 1331 | */ |
| 1332 | if (!use_conflict(ep->pred, ep->succ->et.succ)) { |
| 1333 | done = 0; |
| 1334 | ep->succ = JT(ep->succ); |
| 1335 | } |
| 1336 | } |
| 1337 | /* |
| 1338 | * For each edge dominator that matches the successor of this |
| 1339 | * edge, promote the edge successor to the its grandchild. |
| 1340 | * |
| 1341 | * XXX We violate the set abstraction here in favor a reasonably |
| 1342 | * efficient loop. |
| 1343 | */ |
| 1344 | top: |
| 1345 | for (i = 0; i < edgewords; ++i) { |
| 1346 | register bpf_u_int32 x = ep->edom[i]; |
| 1347 | |
| 1348 | while (x != 0) { |
| 1349 | k = ffs(x) - 1; |
| 1350 | x &=~ (1 << k); |
| 1351 | k += i * BITS_PER_WORD; |
| 1352 | |
| 1353 | target = fold_edge(ep->succ, edges[k]); |
| 1354 | /* |
| 1355 | * Check that there is no data dependency between |
| 1356 | * nodes that will be violated if we move the edge. |
| 1357 | */ |
| 1358 | if (target != 0 && !use_conflict(ep->pred, target)) { |
| 1359 | done = 0; |
| 1360 | ep->succ = target; |
| 1361 | if (JT(target) != 0) |
| 1362 | /* |
| 1363 | * Start over unless we hit a leaf. |
| 1364 | */ |
| 1365 | goto top; |
| 1366 | return; |
| 1367 | } |
| 1368 | } |
| 1369 | } |
| 1370 | } |
| 1371 | |
| 1372 | |
| 1373 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1374 | or_pullup(struct block *b) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1375 | { |
| 1376 | int val, at_top; |
| 1377 | struct block *pull; |
| 1378 | struct block **diffp, **samep; |
| 1379 | struct edge *ep; |
| 1380 | |
| 1381 | ep = b->in_edges; |
| 1382 | if (ep == 0) |
| 1383 | return; |
| 1384 | |
| 1385 | /* |
| 1386 | * Make sure each predecessor loads the same value. |
| 1387 | * XXX why? |
| 1388 | */ |
| 1389 | val = ep->pred->val[A_ATOM]; |
| 1390 | for (ep = ep->next; ep != 0; ep = ep->next) |
| 1391 | if (val != ep->pred->val[A_ATOM]) |
| 1392 | return; |
| 1393 | |
| 1394 | if (JT(b->in_edges->pred) == b) |
| 1395 | diffp = &JT(b->in_edges->pred); |
| 1396 | else |
| 1397 | diffp = &JF(b->in_edges->pred); |
| 1398 | |
| 1399 | at_top = 1; |
| 1400 | while (1) { |
| 1401 | if (*diffp == 0) |
| 1402 | return; |
| 1403 | |
| 1404 | if (JT(*diffp) != JT(b)) |
| 1405 | return; |
| 1406 | |
| 1407 | if (!SET_MEMBER((*diffp)->dom, b->id)) |
| 1408 | return; |
| 1409 | |
| 1410 | if ((*diffp)->val[A_ATOM] != val) |
| 1411 | break; |
| 1412 | |
| 1413 | diffp = &JF(*diffp); |
| 1414 | at_top = 0; |
| 1415 | } |
| 1416 | samep = &JF(*diffp); |
| 1417 | while (1) { |
| 1418 | if (*samep == 0) |
| 1419 | return; |
| 1420 | |
| 1421 | if (JT(*samep) != JT(b)) |
| 1422 | return; |
| 1423 | |
| 1424 | if (!SET_MEMBER((*samep)->dom, b->id)) |
| 1425 | return; |
| 1426 | |
| 1427 | if ((*samep)->val[A_ATOM] == val) |
| 1428 | break; |
| 1429 | |
| 1430 | /* XXX Need to check that there are no data dependencies |
| 1431 | between dp0 and dp1. Currently, the code generator |
| 1432 | will not produce such dependencies. */ |
| 1433 | samep = &JF(*samep); |
| 1434 | } |
| 1435 | #ifdef notdef |
| 1436 | /* XXX This doesn't cover everything. */ |
| 1437 | for (i = 0; i < N_ATOMS; ++i) |
| 1438 | if ((*samep)->val[i] != pred->val[i]) |
| 1439 | return; |
| 1440 | #endif |
| 1441 | /* Pull up the node. */ |
| 1442 | pull = *samep; |
| 1443 | *samep = JF(pull); |
| 1444 | JF(pull) = *diffp; |
| 1445 | |
| 1446 | /* |
| 1447 | * At the top of the chain, each predecessor needs to point at the |
| 1448 | * pulled up node. Inside the chain, there is only one predecessor |
| 1449 | * to worry about. |
| 1450 | */ |
| 1451 | if (at_top) { |
| 1452 | for (ep = b->in_edges; ep != 0; ep = ep->next) { |
| 1453 | if (JT(ep->pred) == b) |
| 1454 | JT(ep->pred) = pull; |
| 1455 | else |
| 1456 | JF(ep->pred) = pull; |
| 1457 | } |
| 1458 | } |
| 1459 | else |
| 1460 | *diffp = pull; |
| 1461 | |
| 1462 | done = 0; |
| 1463 | } |
| 1464 | |
| 1465 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1466 | and_pullup(struct block *b) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1467 | { |
| 1468 | int val, at_top; |
| 1469 | struct block *pull; |
| 1470 | struct block **diffp, **samep; |
| 1471 | struct edge *ep; |
| 1472 | |
| 1473 | ep = b->in_edges; |
| 1474 | if (ep == 0) |
| 1475 | return; |
| 1476 | |
| 1477 | /* |
| 1478 | * Make sure each predecessor loads the same value. |
| 1479 | */ |
| 1480 | val = ep->pred->val[A_ATOM]; |
| 1481 | for (ep = ep->next; ep != 0; ep = ep->next) |
| 1482 | if (val != ep->pred->val[A_ATOM]) |
| 1483 | return; |
| 1484 | |
| 1485 | if (JT(b->in_edges->pred) == b) |
| 1486 | diffp = &JT(b->in_edges->pred); |
| 1487 | else |
| 1488 | diffp = &JF(b->in_edges->pred); |
| 1489 | |
| 1490 | at_top = 1; |
| 1491 | while (1) { |
| 1492 | if (*diffp == 0) |
| 1493 | return; |
| 1494 | |
| 1495 | if (JF(*diffp) != JF(b)) |
| 1496 | return; |
| 1497 | |
| 1498 | if (!SET_MEMBER((*diffp)->dom, b->id)) |
| 1499 | return; |
| 1500 | |
| 1501 | if ((*diffp)->val[A_ATOM] != val) |
| 1502 | break; |
| 1503 | |
| 1504 | diffp = &JT(*diffp); |
| 1505 | at_top = 0; |
| 1506 | } |
| 1507 | samep = &JT(*diffp); |
| 1508 | while (1) { |
| 1509 | if (*samep == 0) |
| 1510 | return; |
| 1511 | |
| 1512 | if (JF(*samep) != JF(b)) |
| 1513 | return; |
| 1514 | |
| 1515 | if (!SET_MEMBER((*samep)->dom, b->id)) |
| 1516 | return; |
| 1517 | |
| 1518 | if ((*samep)->val[A_ATOM] == val) |
| 1519 | break; |
| 1520 | |
| 1521 | /* XXX Need to check that there are no data dependencies |
| 1522 | between diffp and samep. Currently, the code generator |
| 1523 | will not produce such dependencies. */ |
| 1524 | samep = &JT(*samep); |
| 1525 | } |
| 1526 | #ifdef notdef |
| 1527 | /* XXX This doesn't cover everything. */ |
| 1528 | for (i = 0; i < N_ATOMS; ++i) |
| 1529 | if ((*samep)->val[i] != pred->val[i]) |
| 1530 | return; |
| 1531 | #endif |
| 1532 | /* Pull up the node. */ |
| 1533 | pull = *samep; |
| 1534 | *samep = JT(pull); |
| 1535 | JT(pull) = *diffp; |
| 1536 | |
| 1537 | /* |
| 1538 | * At the top of the chain, each predecessor needs to point at the |
| 1539 | * pulled up node. Inside the chain, there is only one predecessor |
| 1540 | * to worry about. |
| 1541 | */ |
| 1542 | if (at_top) { |
| 1543 | for (ep = b->in_edges; ep != 0; ep = ep->next) { |
| 1544 | if (JT(ep->pred) == b) |
| 1545 | JT(ep->pred) = pull; |
| 1546 | else |
| 1547 | JF(ep->pred) = pull; |
| 1548 | } |
| 1549 | } |
| 1550 | else |
| 1551 | *diffp = pull; |
| 1552 | |
| 1553 | done = 0; |
| 1554 | } |
| 1555 | |
| 1556 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1557 | opt_blks(struct block *root, int do_stmts) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1558 | { |
| 1559 | int i, maxlevel; |
| 1560 | struct block *p; |
| 1561 | |
| 1562 | init_val(); |
| 1563 | maxlevel = root->level; |
| 1564 | |
| 1565 | find_inedges(root); |
| 1566 | for (i = maxlevel; i >= 0; --i) |
| 1567 | for (p = levels[i]; p; p = p->link) |
| 1568 | opt_blk(p, do_stmts); |
| 1569 | |
| 1570 | if (do_stmts) |
| 1571 | /* |
| 1572 | * No point trying to move branches; it can't possibly |
| 1573 | * make a difference at this point. |
| 1574 | */ |
| 1575 | return; |
| 1576 | |
| 1577 | for (i = 1; i <= maxlevel; ++i) { |
| 1578 | for (p = levels[i]; p; p = p->link) { |
| 1579 | opt_j(&p->et); |
| 1580 | opt_j(&p->ef); |
| 1581 | } |
| 1582 | } |
| 1583 | |
| 1584 | find_inedges(root); |
| 1585 | for (i = 1; i <= maxlevel; ++i) { |
| 1586 | for (p = levels[i]; p; p = p->link) { |
| 1587 | or_pullup(p); |
| 1588 | and_pullup(p); |
| 1589 | } |
| 1590 | } |
| 1591 | } |
| 1592 | |
| 1593 | static inline void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1594 | link_inedge(struct edge *parent, struct block *child) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1595 | { |
| 1596 | parent->next = child->in_edges; |
| 1597 | child->in_edges = parent; |
| 1598 | } |
| 1599 | |
| 1600 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1601 | find_inedges(struct block *root) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1602 | { |
| 1603 | int i; |
| 1604 | struct block *b; |
| 1605 | |
| 1606 | for (i = 0; i < n_blocks; ++i) |
| 1607 | blocks[i]->in_edges = 0; |
| 1608 | |
| 1609 | /* |
| 1610 | * Traverse the graph, adding each edge to the predecessor |
| 1611 | * list of its successors. Skip the leaves (i.e. level 0). |
| 1612 | */ |
| 1613 | for (i = root->level; i > 0; --i) { |
| 1614 | for (b = levels[i]; b != 0; b = b->link) { |
| 1615 | link_inedge(&b->et, JT(b)); |
| 1616 | link_inedge(&b->ef, JF(b)); |
| 1617 | } |
| 1618 | } |
| 1619 | } |
| 1620 | |
| 1621 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1622 | opt_root(struct block **b) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1623 | { |
| 1624 | struct slist *tmp, *s; |
| 1625 | |
| 1626 | s = (*b)->stmts; |
| 1627 | (*b)->stmts = 0; |
| 1628 | while (BPF_CLASS((*b)->s.code) == BPF_JMP && JT(*b) == JF(*b)) |
| 1629 | *b = JT(*b); |
| 1630 | |
| 1631 | tmp = (*b)->stmts; |
| 1632 | if (tmp != 0) |
| 1633 | sappend(s, tmp); |
| 1634 | (*b)->stmts = s; |
| 1635 | |
| 1636 | /* |
| 1637 | * If the root node is a return, then there is no |
| 1638 | * point executing any statements (since the bpf machine |
| 1639 | * has no side effects). |
| 1640 | */ |
| 1641 | if (BPF_CLASS((*b)->s.code) == BPF_RET) |
| 1642 | (*b)->stmts = 0; |
| 1643 | } |
| 1644 | |
| 1645 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1646 | opt_loop(struct block *root, int do_stmts) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1647 | { |
| 1648 | |
| 1649 | #ifdef BDEBUG |
| 1650 | if (dflag > 1) { |
| 1651 | printf("opt_loop(root, %d) begin\n", do_stmts); |
| 1652 | opt_dump(root); |
| 1653 | } |
| 1654 | #endif |
| 1655 | do { |
| 1656 | done = 1; |
| 1657 | find_levels(root); |
| 1658 | find_dom(root); |
| 1659 | find_closure(root); |
| 1660 | find_ud(root); |
| 1661 | find_edom(root); |
| 1662 | opt_blks(root, do_stmts); |
| 1663 | #ifdef BDEBUG |
| 1664 | if (dflag > 1) { |
| 1665 | printf("opt_loop(root, %d) bottom, done=%d\n", do_stmts, done); |
| 1666 | opt_dump(root); |
| 1667 | } |
| 1668 | #endif |
| 1669 | } while (!done); |
| 1670 | } |
| 1671 | |
| 1672 | /* |
| 1673 | * Optimize the filter code in its dag representation. |
| 1674 | */ |
| 1675 | void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1676 | bpf_optimize(struct block **rootp) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1677 | { |
| 1678 | struct block *root; |
| 1679 | |
| 1680 | root = *rootp; |
| 1681 | |
| 1682 | opt_init(root); |
| 1683 | opt_loop(root, 0); |
| 1684 | opt_loop(root, 1); |
| 1685 | intern_blocks(root); |
| 1686 | #ifdef BDEBUG |
| 1687 | if (dflag > 1) { |
| 1688 | printf("after intern_blocks()\n"); |
| 1689 | opt_dump(root); |
| 1690 | } |
| 1691 | #endif |
| 1692 | opt_root(rootp); |
| 1693 | #ifdef BDEBUG |
| 1694 | if (dflag > 1) { |
| 1695 | printf("after opt_root()\n"); |
| 1696 | opt_dump(root); |
| 1697 | } |
| 1698 | #endif |
| 1699 | opt_cleanup(); |
| 1700 | } |
| 1701 | |
| 1702 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1703 | make_marks(struct block *p) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1704 | { |
| 1705 | if (!isMarked(p)) { |
| 1706 | Mark(p); |
| 1707 | if (BPF_CLASS(p->s.code) != BPF_RET) { |
| 1708 | make_marks(JT(p)); |
| 1709 | make_marks(JF(p)); |
| 1710 | } |
| 1711 | } |
| 1712 | } |
| 1713 | |
| 1714 | /* |
| 1715 | * Mark code array such that isMarked(i) is true |
| 1716 | * only for nodes that are alive. |
| 1717 | */ |
| 1718 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1719 | mark_code(struct block *p) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1720 | { |
| 1721 | cur_mark += 1; |
| 1722 | make_marks(p); |
| 1723 | } |
| 1724 | |
| 1725 | /* |
| 1726 | * True iff the two stmt lists load the same value from the packet into |
| 1727 | * the accumulator. |
| 1728 | */ |
| 1729 | static int |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1730 | eq_slist(struct slist *x, struct slist *y) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1731 | { |
| 1732 | while (1) { |
| 1733 | while (x && x->s.code == NOP) |
| 1734 | x = x->next; |
| 1735 | while (y && y->s.code == NOP) |
| 1736 | y = y->next; |
| 1737 | if (x == 0) |
| 1738 | return y == 0; |
| 1739 | if (y == 0) |
| 1740 | return x == 0; |
| 1741 | if (x->s.code != y->s.code || x->s.k != y->s.k) |
| 1742 | return 0; |
| 1743 | x = x->next; |
| 1744 | y = y->next; |
| 1745 | } |
| 1746 | } |
| 1747 | |
| 1748 | static inline int |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1749 | eq_blk(struct block *b0, struct block *b1) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1750 | { |
| 1751 | if (b0->s.code == b1->s.code && |
| 1752 | b0->s.k == b1->s.k && |
| 1753 | b0->et.succ == b1->et.succ && |
| 1754 | b0->ef.succ == b1->ef.succ) |
| 1755 | return eq_slist(b0->stmts, b1->stmts); |
| 1756 | return 0; |
| 1757 | } |
| 1758 | |
| 1759 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1760 | intern_blocks(struct block *root) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1761 | { |
| 1762 | struct block *p; |
| 1763 | int i, j; |
| 1764 | int done1; /* don't shadow global */ |
| 1765 | top: |
| 1766 | done1 = 1; |
| 1767 | for (i = 0; i < n_blocks; ++i) |
| 1768 | blocks[i]->link = 0; |
| 1769 | |
| 1770 | mark_code(root); |
| 1771 | |
| 1772 | for (i = n_blocks - 1; --i >= 0; ) { |
| 1773 | if (!isMarked(blocks[i])) |
| 1774 | continue; |
| 1775 | for (j = i + 1; j < n_blocks; ++j) { |
| 1776 | if (!isMarked(blocks[j])) |
| 1777 | continue; |
| 1778 | if (eq_blk(blocks[i], blocks[j])) { |
| 1779 | blocks[i]->link = blocks[j]->link ? |
| 1780 | blocks[j]->link : blocks[j]; |
| 1781 | break; |
| 1782 | } |
| 1783 | } |
| 1784 | } |
| 1785 | for (i = 0; i < n_blocks; ++i) { |
| 1786 | p = blocks[i]; |
| 1787 | if (JT(p) == 0) |
| 1788 | continue; |
| 1789 | if (JT(p)->link) { |
| 1790 | done1 = 0; |
| 1791 | JT(p) = JT(p)->link; |
| 1792 | } |
| 1793 | if (JF(p)->link) { |
| 1794 | done1 = 0; |
| 1795 | JF(p) = JF(p)->link; |
| 1796 | } |
| 1797 | } |
| 1798 | if (!done1) |
| 1799 | goto top; |
| 1800 | } |
| 1801 | |
| 1802 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1803 | opt_cleanup(void) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1804 | { |
| 1805 | free((void *)vnode_base); |
| 1806 | free((void *)vmap); |
| 1807 | free((void *)edges); |
| 1808 | free((void *)space); |
| 1809 | free((void *)levels); |
| 1810 | free((void *)blocks); |
| 1811 | } |
| 1812 | |
| 1813 | /* |
| 1814 | * Return the number of stmts in 's'. |
| 1815 | */ |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1816 | static u_int |
| 1817 | slength(struct slist *s) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1818 | { |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1819 | u_int n = 0; |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1820 | |
| 1821 | for (; s; s = s->next) |
| 1822 | if (s->s.code != NOP) |
| 1823 | ++n; |
| 1824 | return n; |
| 1825 | } |
| 1826 | |
| 1827 | /* |
| 1828 | * Return the number of nodes reachable by 'p'. |
| 1829 | * All nodes should be initially unmarked. |
| 1830 | */ |
| 1831 | static int |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1832 | count_blocks(struct block *p) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1833 | { |
| 1834 | if (p == 0 || isMarked(p)) |
| 1835 | return 0; |
| 1836 | Mark(p); |
| 1837 | return count_blocks(JT(p)) + count_blocks(JF(p)) + 1; |
| 1838 | } |
| 1839 | |
| 1840 | /* |
| 1841 | * Do a depth first search on the flow graph, numbering the |
| 1842 | * the basic blocks, and entering them into the 'blocks' array.` |
| 1843 | */ |
| 1844 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1845 | number_blks_r(struct block *p) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1846 | { |
| 1847 | int n; |
| 1848 | |
| 1849 | if (p == 0 || isMarked(p)) |
| 1850 | return; |
| 1851 | |
| 1852 | Mark(p); |
| 1853 | n = n_blocks++; |
| 1854 | p->id = n; |
| 1855 | blocks[n] = p; |
| 1856 | |
| 1857 | number_blks_r(JT(p)); |
| 1858 | number_blks_r(JF(p)); |
| 1859 | } |
| 1860 | |
| 1861 | /* |
| 1862 | * Return the number of stmts in the flowgraph reachable by 'p'. |
| 1863 | * The nodes should be unmarked before calling. |
| 1864 | * |
| 1865 | * Note that "stmts" means "instructions", and that this includes |
| 1866 | * |
| 1867 | * side-effect statements in 'p' (slength(p->stmts)); |
| 1868 | * |
| 1869 | * statements in the true branch from 'p' (count_stmts(JT(p))); |
| 1870 | * |
| 1871 | * statements in the false branch from 'p' (count_stmts(JF(p))); |
| 1872 | * |
| 1873 | * the conditional jump itself (1); |
| 1874 | * |
| 1875 | * an extra long jump if the true branch requires it (p->longjt); |
| 1876 | * |
| 1877 | * an extra long jump if the false branch requires it (p->longjf). |
| 1878 | */ |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1879 | static u_int |
| 1880 | count_stmts(struct block *p) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1881 | { |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1882 | u_int n; |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1883 | |
| 1884 | if (p == 0 || isMarked(p)) |
| 1885 | return 0; |
| 1886 | Mark(p); |
| 1887 | n = count_stmts(JT(p)) + count_stmts(JF(p)); |
| 1888 | return slength(p->stmts) + n + 1 + p->longjt + p->longjf; |
| 1889 | } |
| 1890 | |
| 1891 | /* |
| 1892 | * Allocate memory. All allocation is done before optimization |
| 1893 | * is begun. A linear bound on the size of all data structures is computed |
| 1894 | * from the total number of blocks and/or statements. |
| 1895 | */ |
| 1896 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1897 | opt_init(struct block *root) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1898 | { |
| 1899 | bpf_u_int32 *p; |
| 1900 | int i, n, max_stmts; |
| 1901 | |
| 1902 | /* |
| 1903 | * First, count the blocks, so we can malloc an array to map |
| 1904 | * block number to block. Then, put the blocks into the array. |
| 1905 | */ |
| 1906 | unMarkAll(); |
| 1907 | n = count_blocks(root); |
| 1908 | blocks = (struct block **)calloc(n, sizeof(*blocks)); |
| 1909 | if (blocks == NULL) |
| 1910 | bpf_error("malloc"); |
| 1911 | unMarkAll(); |
| 1912 | n_blocks = 0; |
| 1913 | number_blks_r(root); |
| 1914 | |
| 1915 | n_edges = 2 * n_blocks; |
| 1916 | edges = (struct edge **)calloc(n_edges, sizeof(*edges)); |
| 1917 | if (edges == NULL) |
| 1918 | bpf_error("malloc"); |
| 1919 | |
| 1920 | /* |
| 1921 | * The number of levels is bounded by the number of nodes. |
| 1922 | */ |
| 1923 | levels = (struct block **)calloc(n_blocks, sizeof(*levels)); |
| 1924 | if (levels == NULL) |
| 1925 | bpf_error("malloc"); |
| 1926 | |
| 1927 | edgewords = n_edges / (8 * sizeof(bpf_u_int32)) + 1; |
| 1928 | nodewords = n_blocks / (8 * sizeof(bpf_u_int32)) + 1; |
| 1929 | |
| 1930 | /* XXX */ |
| 1931 | space = (bpf_u_int32 *)malloc(2 * n_blocks * nodewords * sizeof(*space) |
| 1932 | + n_edges * edgewords * sizeof(*space)); |
| 1933 | if (space == NULL) |
| 1934 | bpf_error("malloc"); |
| 1935 | p = space; |
| 1936 | all_dom_sets = p; |
| 1937 | for (i = 0; i < n; ++i) { |
| 1938 | blocks[i]->dom = p; |
| 1939 | p += nodewords; |
| 1940 | } |
| 1941 | all_closure_sets = p; |
| 1942 | for (i = 0; i < n; ++i) { |
| 1943 | blocks[i]->closure = p; |
| 1944 | p += nodewords; |
| 1945 | } |
| 1946 | all_edge_sets = p; |
| 1947 | for (i = 0; i < n; ++i) { |
| 1948 | register struct block *b = blocks[i]; |
| 1949 | |
| 1950 | b->et.edom = p; |
| 1951 | p += edgewords; |
| 1952 | b->ef.edom = p; |
| 1953 | p += edgewords; |
| 1954 | b->et.id = i; |
| 1955 | edges[i] = &b->et; |
| 1956 | b->ef.id = n_blocks + i; |
| 1957 | edges[n_blocks + i] = &b->ef; |
| 1958 | b->et.pred = b; |
| 1959 | b->ef.pred = b; |
| 1960 | } |
| 1961 | max_stmts = 0; |
| 1962 | for (i = 0; i < n; ++i) |
| 1963 | max_stmts += slength(blocks[i]->stmts) + 1; |
| 1964 | /* |
| 1965 | * We allocate at most 3 value numbers per statement, |
| 1966 | * so this is an upper bound on the number of valnodes |
| 1967 | * we'll need. |
| 1968 | */ |
| 1969 | maxval = 3 * max_stmts; |
| 1970 | vmap = (struct vmapinfo *)calloc(maxval, sizeof(*vmap)); |
| 1971 | vnode_base = (struct valnode *)calloc(maxval, sizeof(*vnode_base)); |
| 1972 | if (vmap == NULL || vnode_base == NULL) |
| 1973 | bpf_error("malloc"); |
| 1974 | } |
| 1975 | |
| 1976 | /* |
| 1977 | * Some pointers used to convert the basic block form of the code, |
| 1978 | * into the array form that BPF requires. 'fstart' will point to |
| 1979 | * the malloc'd array while 'ftail' is used during the recursive traversal. |
| 1980 | */ |
| 1981 | static struct bpf_insn *fstart; |
| 1982 | static struct bpf_insn *ftail; |
| 1983 | |
| 1984 | #ifdef BDEBUG |
| 1985 | int bids[1000]; |
| 1986 | #endif |
| 1987 | |
| 1988 | /* |
| 1989 | * Returns true if successful. Returns false if a branch has |
| 1990 | * an offset that is too large. If so, we have marked that |
| 1991 | * branch so that on a subsequent iteration, it will be treated |
| 1992 | * properly. |
| 1993 | */ |
| 1994 | static int |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 1995 | convert_code_r(struct block *p) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 1996 | { |
| 1997 | struct bpf_insn *dst; |
| 1998 | struct slist *src; |
| 1999 | int slen; |
| 2000 | u_int off; |
| 2001 | int extrajmps; /* number of extra jumps inserted */ |
| 2002 | struct slist **offset = NULL; |
| 2003 | |
| 2004 | if (p == 0 || isMarked(p)) |
| 2005 | return (1); |
| 2006 | Mark(p); |
| 2007 | |
| 2008 | if (convert_code_r(JF(p)) == 0) |
| 2009 | return (0); |
| 2010 | if (convert_code_r(JT(p)) == 0) |
| 2011 | return (0); |
| 2012 | |
| 2013 | slen = slength(p->stmts); |
| 2014 | dst = ftail -= (slen + 1 + p->longjt + p->longjf); |
| 2015 | /* inflate length by any extra jumps */ |
| 2016 | |
| 2017 | p->offset = dst - fstart; |
| 2018 | |
| 2019 | /* generate offset[] for convenience */ |
| 2020 | if (slen) { |
| 2021 | offset = (struct slist **)calloc(slen, sizeof(struct slist *)); |
| 2022 | if (!offset) { |
| 2023 | bpf_error("not enough core"); |
| 2024 | /*NOTREACHED*/ |
| 2025 | } |
| 2026 | } |
| 2027 | src = p->stmts; |
| 2028 | for (off = 0; off < slen && src; off++) { |
| 2029 | #if 0 |
| 2030 | printf("off=%d src=%x\n", off, src); |
| 2031 | #endif |
| 2032 | offset[off] = src; |
| 2033 | src = src->next; |
| 2034 | } |
| 2035 | |
| 2036 | off = 0; |
| 2037 | for (src = p->stmts; src; src = src->next) { |
| 2038 | if (src->s.code == NOP) |
| 2039 | continue; |
| 2040 | dst->code = (u_short)src->s.code; |
| 2041 | dst->k = src->s.k; |
| 2042 | |
| 2043 | /* fill block-local relative jump */ |
| 2044 | if (BPF_CLASS(src->s.code) != BPF_JMP || src->s.code == (BPF_JMP|BPF_JA)) { |
| 2045 | #if 0 |
| 2046 | if (src->s.jt || src->s.jf) { |
| 2047 | bpf_error("illegal jmp destination"); |
| 2048 | /*NOTREACHED*/ |
| 2049 | } |
| 2050 | #endif |
| 2051 | goto filled; |
| 2052 | } |
| 2053 | if (off == slen - 2) /*???*/ |
| 2054 | goto filled; |
| 2055 | |
| 2056 | { |
| 2057 | int i; |
| 2058 | int jt, jf; |
| 2059 | const char *ljerr = "%s for block-local relative jump: off=%d"; |
| 2060 | |
| 2061 | #if 0 |
| 2062 | printf("code=%x off=%d %x %x\n", src->s.code, |
| 2063 | off, src->s.jt, src->s.jf); |
| 2064 | #endif |
| 2065 | |
| 2066 | if (!src->s.jt || !src->s.jf) { |
| 2067 | bpf_error(ljerr, "no jmp destination", off); |
| 2068 | /*NOTREACHED*/ |
| 2069 | } |
| 2070 | |
| 2071 | jt = jf = 0; |
| 2072 | for (i = 0; i < slen; i++) { |
| 2073 | if (offset[i] == src->s.jt) { |
| 2074 | if (jt) { |
| 2075 | bpf_error(ljerr, "multiple matches", off); |
| 2076 | /*NOTREACHED*/ |
| 2077 | } |
| 2078 | |
| 2079 | dst->jt = i - off - 1; |
| 2080 | jt++; |
| 2081 | } |
| 2082 | if (offset[i] == src->s.jf) { |
| 2083 | if (jf) { |
| 2084 | bpf_error(ljerr, "multiple matches", off); |
| 2085 | /*NOTREACHED*/ |
| 2086 | } |
| 2087 | dst->jf = i - off - 1; |
| 2088 | jf++; |
| 2089 | } |
| 2090 | } |
| 2091 | if (!jt || !jf) { |
| 2092 | bpf_error(ljerr, "no destination found", off); |
| 2093 | /*NOTREACHED*/ |
| 2094 | } |
| 2095 | } |
| 2096 | filled: |
| 2097 | ++dst; |
| 2098 | ++off; |
| 2099 | } |
| 2100 | if (offset) |
| 2101 | free(offset); |
| 2102 | |
| 2103 | #ifdef BDEBUG |
| 2104 | bids[dst - fstart] = p->id + 1; |
| 2105 | #endif |
| 2106 | dst->code = (u_short)p->s.code; |
| 2107 | dst->k = p->s.k; |
| 2108 | if (JT(p)) { |
| 2109 | extrajmps = 0; |
| 2110 | off = JT(p)->offset - (p->offset + slen) - 1; |
| 2111 | if (off >= 256) { |
| 2112 | /* offset too large for branch, must add a jump */ |
| 2113 | if (p->longjt == 0) { |
| 2114 | /* mark this instruction and retry */ |
| 2115 | p->longjt++; |
| 2116 | return(0); |
| 2117 | } |
| 2118 | /* branch if T to following jump */ |
| 2119 | dst->jt = extrajmps; |
| 2120 | extrajmps++; |
| 2121 | dst[extrajmps].code = BPF_JMP|BPF_JA; |
| 2122 | dst[extrajmps].k = off - extrajmps; |
| 2123 | } |
| 2124 | else |
| 2125 | dst->jt = off; |
| 2126 | off = JF(p)->offset - (p->offset + slen) - 1; |
| 2127 | if (off >= 256) { |
| 2128 | /* offset too large for branch, must add a jump */ |
| 2129 | if (p->longjf == 0) { |
| 2130 | /* mark this instruction and retry */ |
| 2131 | p->longjf++; |
| 2132 | return(0); |
| 2133 | } |
| 2134 | /* branch if F to following jump */ |
| 2135 | /* if two jumps are inserted, F goes to second one */ |
| 2136 | dst->jf = extrajmps; |
| 2137 | extrajmps++; |
| 2138 | dst[extrajmps].code = BPF_JMP|BPF_JA; |
| 2139 | dst[extrajmps].k = off - extrajmps; |
| 2140 | } |
| 2141 | else |
| 2142 | dst->jf = off; |
| 2143 | } |
| 2144 | return (1); |
| 2145 | } |
| 2146 | |
| 2147 | |
| 2148 | /* |
| 2149 | * Convert flowgraph intermediate representation to the |
| 2150 | * BPF array representation. Set *lenp to the number of instructions. |
| 2151 | * |
| 2152 | * This routine does *NOT* leak the memory pointed to by fp. It *must |
| 2153 | * not* do free(fp) before returning fp; doing so would make no sense, |
| 2154 | * as the BPF array pointed to by the return value of icode_to_fcode() |
| 2155 | * must be valid - it's being returned for use in a bpf_program structure. |
| 2156 | * |
| 2157 | * If it appears that icode_to_fcode() is leaking, the problem is that |
| 2158 | * the program using pcap_compile() is failing to free the memory in |
| 2159 | * the BPF program when it's done - the leak is in the program, not in |
| 2160 | * the routine that happens to be allocating the memory. (By analogy, if |
| 2161 | * a program calls fopen() without ever calling fclose() on the FILE *, |
| 2162 | * it will leak the FILE structure; the leak is not in fopen(), it's in |
| 2163 | * the program.) Change the program to use pcap_freecode() when it's |
| 2164 | * done with the filter program. See the pcap man page. |
| 2165 | */ |
| 2166 | struct bpf_insn * |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 2167 | icode_to_fcode(struct block *root, u_int *lenp) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 2168 | { |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 2169 | u_int n; |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 2170 | struct bpf_insn *fp; |
| 2171 | |
| 2172 | /* |
| 2173 | * Loop doing convert_code_r() until no branches remain |
| 2174 | * with too-large offsets. |
| 2175 | */ |
| 2176 | while (1) { |
| 2177 | unMarkAll(); |
| 2178 | n = *lenp = count_stmts(root); |
| 2179 | |
| 2180 | fp = (struct bpf_insn *)malloc(sizeof(*fp) * n); |
| 2181 | if (fp == NULL) |
| 2182 | bpf_error("malloc"); |
| 2183 | memset((char *)fp, 0, sizeof(*fp) * n); |
| 2184 | fstart = fp; |
| 2185 | ftail = fp + n; |
| 2186 | |
| 2187 | unMarkAll(); |
| 2188 | if (convert_code_r(root)) |
| 2189 | break; |
| 2190 | free(fp); |
| 2191 | } |
| 2192 | |
| 2193 | return fp; |
| 2194 | } |
| 2195 | |
| 2196 | /* |
| 2197 | * Make a copy of a BPF program and put it in the "fcode" member of |
| 2198 | * a "pcap_t". |
| 2199 | * |
| 2200 | * If we fail to allocate memory for the copy, fill in the "errbuf" |
| 2201 | * member of the "pcap_t" with an error message, and return -1; |
| 2202 | * otherwise, return 0. |
| 2203 | */ |
| 2204 | int |
| 2205 | install_bpf_program(pcap_t *p, struct bpf_program *fp) |
| 2206 | { |
| 2207 | size_t prog_size; |
| 2208 | |
| 2209 | /* |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 2210 | * Validate the program. |
| 2211 | */ |
| 2212 | if (!bpf_validate(fp->bf_insns, fp->bf_len)) { |
| 2213 | snprintf(p->errbuf, sizeof(p->errbuf), |
| 2214 | "BPF program is not valid"); |
| 2215 | return (-1); |
| 2216 | } |
| 2217 | |
| 2218 | /* |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 2219 | * Free up any already installed program. |
| 2220 | */ |
| 2221 | pcap_freecode(&p->fcode); |
| 2222 | |
| 2223 | prog_size = sizeof(*fp->bf_insns) * fp->bf_len; |
| 2224 | p->fcode.bf_len = fp->bf_len; |
| 2225 | p->fcode.bf_insns = (struct bpf_insn *)malloc(prog_size); |
| 2226 | if (p->fcode.bf_insns == NULL) { |
| 2227 | snprintf(p->errbuf, sizeof(p->errbuf), |
| 2228 | "malloc: %s", pcap_strerror(errno)); |
| 2229 | return (-1); |
| 2230 | } |
| 2231 | memcpy(p->fcode.bf_insns, fp->bf_insns, prog_size); |
| 2232 | return (0); |
| 2233 | } |
| 2234 | |
| 2235 | #ifdef BDEBUG |
| 2236 | static void |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 2237 | opt_dump(struct block *root) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 2238 | { |
| 2239 | struct bpf_program f; |
| 2240 | |
| 2241 | memset(bids, 0, sizeof bids); |
| 2242 | f.bf_insns = icode_to_fcode(root, &f.bf_len); |
| 2243 | bpf_dump(&f, 1); |
| 2244 | putchar('\n'); |
| 2245 | free((char *)f.bf_insns); |
| 2246 | } |
| 2247 | #endif |