1 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) 2 /* Copyright (C) 2018 Netronome Systems, Inc. */ 3 4 #include <linux/list.h> 5 #include <stdlib.h> 6 #include <string.h> 7 8 #include "cfg.h" 9 #include "main.h" 10 #include "xlated_dumper.h" 11 12 struct cfg { 13 struct list_head funcs; 14 int func_num; 15 }; 16 17 struct func_node { 18 struct list_head l; 19 struct list_head bbs; 20 struct bpf_insn *start; 21 struct bpf_insn *end; 22 int idx; 23 int bb_num; 24 }; 25 26 struct bb_node { 27 struct list_head l; 28 struct list_head e_prevs; 29 struct list_head e_succs; 30 struct bpf_insn *head; 31 struct bpf_insn *tail; 32 int idx; 33 }; 34 35 #define EDGE_FLAG_EMPTY 0x0 36 #define EDGE_FLAG_FALLTHROUGH 0x1 37 #define EDGE_FLAG_JUMP 0x2 38 struct edge_node { 39 struct list_head l; 40 struct bb_node *src; 41 struct bb_node *dst; 42 int flags; 43 }; 44 45 #define ENTRY_BLOCK_INDEX 0 46 #define EXIT_BLOCK_INDEX 1 47 #define NUM_FIXED_BLOCKS 2 48 #define func_prev(func) list_prev_entry(func, l) 49 #define func_next(func) list_next_entry(func, l) 50 #define bb_prev(bb) list_prev_entry(bb, l) 51 #define bb_next(bb) list_next_entry(bb, l) 52 #define entry_bb(func) func_first_bb(func) 53 #define exit_bb(func) func_last_bb(func) 54 #define cfg_first_func(cfg) \ 55 list_first_entry(&cfg->funcs, struct func_node, l) 56 #define cfg_last_func(cfg) \ 57 list_last_entry(&cfg->funcs, struct func_node, l) 58 #define func_first_bb(func) \ 59 list_first_entry(&func->bbs, struct bb_node, l) 60 #define func_last_bb(func) \ 61 list_last_entry(&func->bbs, struct bb_node, l) 62 63 static struct func_node *cfg_append_func(struct cfg *cfg, struct bpf_insn *insn) 64 { 65 struct func_node *new_func, *func; 66 67 list_for_each_entry(func, &cfg->funcs, l) { 68 if (func->start == insn) 69 return func; 70 else if (func->start > insn) 71 break; 72 } 73 74 func = func_prev(func); 75 new_func = calloc(1, sizeof(*new_func)); 76 if (!new_func) { 77 p_err("OOM when allocating FUNC node"); 78 return NULL; 79 } 80 new_func->start = insn; 81 new_func->idx = cfg->func_num; 82 list_add(&new_func->l, &func->l); 83 cfg->func_num++; 84 85 return new_func; 86 } 87 88 static struct bb_node *func_append_bb(struct func_node *func, 89 struct bpf_insn *insn) 90 { 91 struct bb_node *new_bb, *bb; 92 93 list_for_each_entry(bb, &func->bbs, l) { 94 if (bb->head == insn) 95 return bb; 96 else if (bb->head > insn) 97 break; 98 } 99 100 bb = bb_prev(bb); 101 new_bb = calloc(1, sizeof(*new_bb)); 102 if (!new_bb) { 103 p_err("OOM when allocating BB node"); 104 return NULL; 105 } 106 new_bb->head = insn; 107 INIT_LIST_HEAD(&new_bb->e_prevs); 108 INIT_LIST_HEAD(&new_bb->e_succs); 109 list_add(&new_bb->l, &bb->l); 110 111 return new_bb; 112 } 113 114 static struct bb_node *func_insert_dummy_bb(struct list_head *after) 115 { 116 struct bb_node *bb; 117 118 bb = calloc(1, sizeof(*bb)); 119 if (!bb) { 120 p_err("OOM when allocating BB node"); 121 return NULL; 122 } 123 124 INIT_LIST_HEAD(&bb->e_prevs); 125 INIT_LIST_HEAD(&bb->e_succs); 126 list_add(&bb->l, after); 127 128 return bb; 129 } 130 131 static bool cfg_partition_funcs(struct cfg *cfg, struct bpf_insn *cur, 132 struct bpf_insn *end) 133 { 134 struct func_node *func, *last_func; 135 136 func = cfg_append_func(cfg, cur); 137 if (!func) 138 return true; 139 140 for (; cur < end; cur++) { 141 if (cur->code != (BPF_JMP | BPF_CALL)) 142 continue; 143 if (cur->src_reg != BPF_PSEUDO_CALL) 144 continue; 145 func = cfg_append_func(cfg, cur + cur->off + 1); 146 if (!func) 147 return true; 148 } 149 150 last_func = cfg_last_func(cfg); 151 last_func->end = end - 1; 152 func = cfg_first_func(cfg); 153 list_for_each_entry_from(func, &last_func->l, l) { 154 func->end = func_next(func)->start - 1; 155 } 156 157 return false; 158 } 159 160 static bool is_jmp_insn(u8 code) 161 { 162 return BPF_CLASS(code) == BPF_JMP || BPF_CLASS(code) == BPF_JMP32; 163 } 164 165 static bool func_partition_bb_head(struct func_node *func) 166 { 167 struct bpf_insn *cur, *end; 168 struct bb_node *bb; 169 170 cur = func->start; 171 end = func->end; 172 INIT_LIST_HEAD(&func->bbs); 173 bb = func_append_bb(func, cur); 174 if (!bb) 175 return true; 176 177 for (; cur <= end; cur++) { 178 if (is_jmp_insn(cur->code)) { 179 u8 opcode = BPF_OP(cur->code); 180 181 if (opcode == BPF_EXIT || opcode == BPF_CALL) 182 continue; 183 184 bb = func_append_bb(func, cur + cur->off + 1); 185 if (!bb) 186 return true; 187 188 if (opcode != BPF_JA) { 189 bb = func_append_bb(func, cur + 1); 190 if (!bb) 191 return true; 192 } 193 } 194 } 195 196 return false; 197 } 198 199 static void func_partition_bb_tail(struct func_node *func) 200 { 201 unsigned int bb_idx = NUM_FIXED_BLOCKS; 202 struct bb_node *bb, *last; 203 204 last = func_last_bb(func); 205 last->tail = func->end; 206 bb = func_first_bb(func); 207 list_for_each_entry_from(bb, &last->l, l) { 208 bb->tail = bb_next(bb)->head - 1; 209 bb->idx = bb_idx++; 210 } 211 212 last->idx = bb_idx++; 213 func->bb_num = bb_idx; 214 } 215 216 static bool func_add_special_bb(struct func_node *func) 217 { 218 struct bb_node *bb; 219 220 bb = func_insert_dummy_bb(&func->bbs); 221 if (!bb) 222 return true; 223 bb->idx = ENTRY_BLOCK_INDEX; 224 225 bb = func_insert_dummy_bb(&func_last_bb(func)->l); 226 if (!bb) 227 return true; 228 bb->idx = EXIT_BLOCK_INDEX; 229 230 return false; 231 } 232 233 static bool func_partition_bb(struct func_node *func) 234 { 235 if (func_partition_bb_head(func)) 236 return true; 237 238 func_partition_bb_tail(func); 239 240 return false; 241 } 242 243 static struct bb_node *func_search_bb_with_head(struct func_node *func, 244 struct bpf_insn *insn) 245 { 246 struct bb_node *bb; 247 248 list_for_each_entry(bb, &func->bbs, l) { 249 if (bb->head == insn) 250 return bb; 251 } 252 253 return NULL; 254 } 255 256 static struct edge_node *new_edge(struct bb_node *src, struct bb_node *dst, 257 int flags) 258 { 259 struct edge_node *e; 260 261 e = calloc(1, sizeof(*e)); 262 if (!e) { 263 p_err("OOM when allocating edge node"); 264 return NULL; 265 } 266 267 if (src) 268 e->src = src; 269 if (dst) 270 e->dst = dst; 271 272 e->flags |= flags; 273 274 return e; 275 } 276 277 static bool func_add_bb_edges(struct func_node *func) 278 { 279 struct bpf_insn *insn; 280 struct edge_node *e; 281 struct bb_node *bb; 282 283 bb = entry_bb(func); 284 e = new_edge(bb, bb_next(bb), EDGE_FLAG_FALLTHROUGH); 285 if (!e) 286 return true; 287 list_add_tail(&e->l, &bb->e_succs); 288 289 bb = exit_bb(func); 290 e = new_edge(bb_prev(bb), bb, EDGE_FLAG_FALLTHROUGH); 291 if (!e) 292 return true; 293 list_add_tail(&e->l, &bb->e_prevs); 294 295 bb = entry_bb(func); 296 bb = bb_next(bb); 297 list_for_each_entry_from(bb, &exit_bb(func)->l, l) { 298 e = new_edge(bb, NULL, EDGE_FLAG_EMPTY); 299 if (!e) 300 return true; 301 e->src = bb; 302 303 insn = bb->tail; 304 if (!is_jmp_insn(insn->code) || 305 BPF_OP(insn->code) == BPF_EXIT) { 306 e->dst = bb_next(bb); 307 e->flags |= EDGE_FLAG_FALLTHROUGH; 308 list_add_tail(&e->l, &bb->e_succs); 309 continue; 310 } else if (BPF_OP(insn->code) == BPF_JA) { 311 e->dst = func_search_bb_with_head(func, 312 insn + insn->off + 1); 313 e->flags |= EDGE_FLAG_JUMP; 314 list_add_tail(&e->l, &bb->e_succs); 315 continue; 316 } 317 318 e->dst = bb_next(bb); 319 e->flags |= EDGE_FLAG_FALLTHROUGH; 320 list_add_tail(&e->l, &bb->e_succs); 321 322 e = new_edge(bb, NULL, EDGE_FLAG_JUMP); 323 if (!e) 324 return true; 325 e->src = bb; 326 e->dst = func_search_bb_with_head(func, insn + insn->off + 1); 327 list_add_tail(&e->l, &bb->e_succs); 328 } 329 330 return false; 331 } 332 333 static bool cfg_build(struct cfg *cfg, struct bpf_insn *insn, unsigned int len) 334 { 335 int cnt = len / sizeof(*insn); 336 struct func_node *func; 337 338 INIT_LIST_HEAD(&cfg->funcs); 339 340 if (cfg_partition_funcs(cfg, insn, insn + cnt)) 341 return true; 342 343 list_for_each_entry(func, &cfg->funcs, l) { 344 if (func_partition_bb(func) || func_add_special_bb(func)) 345 return true; 346 347 if (func_add_bb_edges(func)) 348 return true; 349 } 350 351 return false; 352 } 353 354 static void cfg_destroy(struct cfg *cfg) 355 { 356 struct func_node *func, *func2; 357 358 list_for_each_entry_safe(func, func2, &cfg->funcs, l) { 359 struct bb_node *bb, *bb2; 360 361 list_for_each_entry_safe(bb, bb2, &func->bbs, l) { 362 struct edge_node *e, *e2; 363 364 list_for_each_entry_safe(e, e2, &bb->e_prevs, l) { 365 list_del(&e->l); 366 free(e); 367 } 368 369 list_for_each_entry_safe(e, e2, &bb->e_succs, l) { 370 list_del(&e->l); 371 free(e); 372 } 373 374 list_del(&bb->l); 375 free(bb); 376 } 377 378 list_del(&func->l); 379 free(func); 380 } 381 } 382 383 static void draw_bb_node(struct func_node *func, struct bb_node *bb) 384 { 385 const char *shape; 386 387 if (bb->idx == ENTRY_BLOCK_INDEX || bb->idx == EXIT_BLOCK_INDEX) 388 shape = "Mdiamond"; 389 else 390 shape = "record"; 391 392 printf("\tfn_%d_bb_%d [shape=%s,style=filled,label=\"", 393 func->idx, bb->idx, shape); 394 395 if (bb->idx == ENTRY_BLOCK_INDEX) { 396 printf("ENTRY"); 397 } else if (bb->idx == EXIT_BLOCK_INDEX) { 398 printf("EXIT"); 399 } else { 400 unsigned int start_idx; 401 struct dump_data dd = {}; 402 403 printf("{"); 404 kernel_syms_load(&dd); 405 start_idx = bb->head - func->start; 406 dump_xlated_for_graph(&dd, bb->head, bb->tail, start_idx); 407 kernel_syms_destroy(&dd); 408 printf("}"); 409 } 410 411 printf("\"];\n\n"); 412 } 413 414 static void draw_bb_succ_edges(struct func_node *func, struct bb_node *bb) 415 { 416 const char *style = "\"solid,bold\""; 417 const char *color = "black"; 418 int func_idx = func->idx; 419 struct edge_node *e; 420 int weight = 10; 421 422 if (list_empty(&bb->e_succs)) 423 return; 424 425 list_for_each_entry(e, &bb->e_succs, l) { 426 printf("\tfn_%d_bb_%d:s -> fn_%d_bb_%d:n [style=%s, color=%s, weight=%d, constraint=true", 427 func_idx, e->src->idx, func_idx, e->dst->idx, 428 style, color, weight); 429 printf("];\n"); 430 } 431 } 432 433 static void func_output_bb_def(struct func_node *func) 434 { 435 struct bb_node *bb; 436 437 list_for_each_entry(bb, &func->bbs, l) { 438 draw_bb_node(func, bb); 439 } 440 } 441 442 static void func_output_edges(struct func_node *func) 443 { 444 int func_idx = func->idx; 445 struct bb_node *bb; 446 447 list_for_each_entry(bb, &func->bbs, l) { 448 draw_bb_succ_edges(func, bb); 449 } 450 451 /* Add an invisible edge from ENTRY to EXIT, this is to 452 * improve the graph layout. 453 */ 454 printf("\tfn_%d_bb_%d:s -> fn_%d_bb_%d:n [style=\"invis\", constraint=true];\n", 455 func_idx, ENTRY_BLOCK_INDEX, func_idx, EXIT_BLOCK_INDEX); 456 } 457 458 static void cfg_dump(struct cfg *cfg) 459 { 460 struct func_node *func; 461 462 printf("digraph \"DOT graph for eBPF program\" {\n"); 463 list_for_each_entry(func, &cfg->funcs, l) { 464 printf("subgraph \"cluster_%d\" {\n\tstyle=\"dashed\";\n\tcolor=\"black\";\n\tlabel=\"func_%d ()\";\n", 465 func->idx, func->idx); 466 func_output_bb_def(func); 467 func_output_edges(func); 468 printf("}\n"); 469 } 470 printf("}\n"); 471 } 472 473 void dump_xlated_cfg(void *buf, unsigned int len) 474 { 475 struct bpf_insn *insn = buf; 476 struct cfg cfg; 477 478 memset(&cfg, 0, sizeof(cfg)); 479 if (cfg_build(&cfg, insn, len)) 480 return; 481 482 cfg_dump(&cfg); 483 484 cfg_destroy(&cfg); 485 } 486