1 /* bpf_jit_comp.c : BPF JIT compiler 2 * 3 * Copyright (C) 2011 Eric Dumazet (eric.dumazet@gmail.com) 4 * 5 * This program is free software; you can redistribute it and/or 6 * modify it under the terms of the GNU General Public License 7 * as published by the Free Software Foundation; version 2 8 * of the License. 9 */ 10 #include <linux/moduleloader.h> 11 #include <asm/cacheflush.h> 12 #include <linux/netdevice.h> 13 #include <linux/filter.h> 14 15 /* 16 * Conventions : 17 * EAX : BPF A accumulator 18 * EBX : BPF X accumulator 19 * RDI : pointer to skb (first argument given to JIT function) 20 * RBP : frame pointer (even if CONFIG_FRAME_POINTER=n) 21 * ECX,EDX,ESI : scratch registers 22 * r9d : skb->len - skb->data_len (headlen) 23 * r8 : skb->data 24 * -8(RBP) : saved RBX value 25 * -16(RBP)..-80(RBP) : BPF_MEMWORDS values 26 */ 27 int bpf_jit_enable __read_mostly; 28 29 /* 30 * assembly code in arch/x86/net/bpf_jit.S 31 */ 32 extern u8 sk_load_word[], sk_load_half[], sk_load_byte[], sk_load_byte_msh[]; 33 extern u8 sk_load_word_positive_offset[], sk_load_half_positive_offset[]; 34 extern u8 sk_load_byte_positive_offset[], sk_load_byte_msh_positive_offset[]; 35 extern u8 sk_load_word_negative_offset[], sk_load_half_negative_offset[]; 36 extern u8 sk_load_byte_negative_offset[], sk_load_byte_msh_negative_offset[]; 37 38 static inline u8 *emit_code(u8 *ptr, u32 bytes, unsigned int len) 39 { 40 if (len == 1) 41 *ptr = bytes; 42 else if (len == 2) 43 *(u16 *)ptr = bytes; 44 else { 45 *(u32 *)ptr = bytes; 46 barrier(); 47 } 48 return ptr + len; 49 } 50 51 #define EMIT(bytes, len) do { prog = emit_code(prog, bytes, len); } while (0) 52 53 #define EMIT1(b1) EMIT(b1, 1) 54 #define EMIT2(b1, b2) EMIT((b1) + ((b2) << 8), 2) 55 #define EMIT3(b1, b2, b3) EMIT((b1) + ((b2) << 8) + ((b3) << 16), 3) 56 #define EMIT4(b1, b2, b3, b4) EMIT((b1) + ((b2) << 8) + ((b3) << 16) + ((b4) << 24), 4) 57 #define EMIT1_off32(b1, off) do { EMIT1(b1); EMIT(off, 4);} while (0) 58 59 #define CLEAR_A() EMIT2(0x31, 0xc0) /* xor %eax,%eax */ 60 #define CLEAR_X() EMIT2(0x31, 0xdb) /* xor %ebx,%ebx */ 61 62 static inline bool is_imm8(int value) 63 { 64 return value <= 127 && value >= -128; 65 } 66 67 static inline bool is_near(int offset) 68 { 69 return offset <= 127 && offset >= -128; 70 } 71 72 #define EMIT_JMP(offset) \ 73 do { \ 74 if (offset) { \ 75 if (is_near(offset)) \ 76 EMIT2(0xeb, offset); /* jmp .+off8 */ \ 77 else \ 78 EMIT1_off32(0xe9, offset); /* jmp .+off32 */ \ 79 } \ 80 } while (0) 81 82 /* list of x86 cond jumps opcodes (. + s8) 83 * Add 0x10 (and an extra 0x0f) to generate far jumps (. + s32) 84 */ 85 #define X86_JB 0x72 86 #define X86_JAE 0x73 87 #define X86_JE 0x74 88 #define X86_JNE 0x75 89 #define X86_JBE 0x76 90 #define X86_JA 0x77 91 92 #define EMIT_COND_JMP(op, offset) \ 93 do { \ 94 if (is_near(offset)) \ 95 EMIT2(op, offset); /* jxx .+off8 */ \ 96 else { \ 97 EMIT2(0x0f, op + 0x10); \ 98 EMIT(offset, 4); /* jxx .+off32 */ \ 99 } \ 100 } while (0) 101 102 #define COND_SEL(CODE, TOP, FOP) \ 103 case CODE: \ 104 t_op = TOP; \ 105 f_op = FOP; \ 106 goto cond_branch 107 108 109 #define SEEN_DATAREF 1 /* might call external helpers */ 110 #define SEEN_XREG 2 /* ebx is used */ 111 #define SEEN_MEM 4 /* use mem[] for temporary storage */ 112 113 static inline void bpf_flush_icache(void *start, void *end) 114 { 115 mm_segment_t old_fs = get_fs(); 116 117 set_fs(KERNEL_DS); 118 smp_wmb(); 119 flush_icache_range((unsigned long)start, (unsigned long)end); 120 set_fs(old_fs); 121 } 122 123 #define CHOOSE_LOAD_FUNC(K, func) \ 124 ((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative_offset : func) : func##_positive_offset) 125 126 void bpf_jit_compile(struct sk_filter *fp) 127 { 128 u8 temp[64]; 129 u8 *prog; 130 unsigned int proglen, oldproglen = 0; 131 int ilen, i; 132 int t_offset, f_offset; 133 u8 t_op, f_op, seen = 0, pass; 134 u8 *image = NULL; 135 u8 *func; 136 int pc_ret0 = -1; /* bpf index of first RET #0 instruction (if any) */ 137 unsigned int cleanup_addr; /* epilogue code offset */ 138 unsigned int *addrs; 139 const struct sock_filter *filter = fp->insns; 140 int flen = fp->len; 141 142 if (!bpf_jit_enable) 143 return; 144 145 addrs = kmalloc(flen * sizeof(*addrs), GFP_KERNEL); 146 if (addrs == NULL) 147 return; 148 149 /* Before first pass, make a rough estimation of addrs[] 150 * each bpf instruction is translated to less than 64 bytes 151 */ 152 for (proglen = 0, i = 0; i < flen; i++) { 153 proglen += 64; 154 addrs[i] = proglen; 155 } 156 cleanup_addr = proglen; /* epilogue address */ 157 158 for (pass = 0; pass < 10; pass++) { 159 u8 seen_or_pass0 = (pass == 0) ? (SEEN_XREG | SEEN_DATAREF | SEEN_MEM) : seen; 160 /* no prologue/epilogue for trivial filters (RET something) */ 161 proglen = 0; 162 prog = temp; 163 164 if (seen_or_pass0) { 165 EMIT4(0x55, 0x48, 0x89, 0xe5); /* push %rbp; mov %rsp,%rbp */ 166 EMIT4(0x48, 0x83, 0xec, 96); /* subq $96,%rsp */ 167 /* note : must save %rbx in case bpf_error is hit */ 168 if (seen_or_pass0 & (SEEN_XREG | SEEN_DATAREF)) 169 EMIT4(0x48, 0x89, 0x5d, 0xf8); /* mov %rbx, -8(%rbp) */ 170 if (seen_or_pass0 & SEEN_XREG) 171 CLEAR_X(); /* make sure we dont leek kernel memory */ 172 173 /* 174 * If this filter needs to access skb data, 175 * loads r9 and r8 with : 176 * r9 = skb->len - skb->data_len 177 * r8 = skb->data 178 */ 179 if (seen_or_pass0 & SEEN_DATAREF) { 180 if (offsetof(struct sk_buff, len) <= 127) 181 /* mov off8(%rdi),%r9d */ 182 EMIT4(0x44, 0x8b, 0x4f, offsetof(struct sk_buff, len)); 183 else { 184 /* mov off32(%rdi),%r9d */ 185 EMIT3(0x44, 0x8b, 0x8f); 186 EMIT(offsetof(struct sk_buff, len), 4); 187 } 188 if (is_imm8(offsetof(struct sk_buff, data_len))) 189 /* sub off8(%rdi),%r9d */ 190 EMIT4(0x44, 0x2b, 0x4f, offsetof(struct sk_buff, data_len)); 191 else { 192 EMIT3(0x44, 0x2b, 0x8f); 193 EMIT(offsetof(struct sk_buff, data_len), 4); 194 } 195 196 if (is_imm8(offsetof(struct sk_buff, data))) 197 /* mov off8(%rdi),%r8 */ 198 EMIT4(0x4c, 0x8b, 0x47, offsetof(struct sk_buff, data)); 199 else { 200 /* mov off32(%rdi),%r8 */ 201 EMIT3(0x4c, 0x8b, 0x87); 202 EMIT(offsetof(struct sk_buff, data), 4); 203 } 204 } 205 } 206 207 switch (filter[0].code) { 208 case BPF_S_RET_K: 209 case BPF_S_LD_W_LEN: 210 case BPF_S_ANC_PROTOCOL: 211 case BPF_S_ANC_IFINDEX: 212 case BPF_S_ANC_MARK: 213 case BPF_S_ANC_RXHASH: 214 case BPF_S_ANC_CPU: 215 case BPF_S_ANC_QUEUE: 216 case BPF_S_LD_W_ABS: 217 case BPF_S_LD_H_ABS: 218 case BPF_S_LD_B_ABS: 219 /* first instruction sets A register (or is RET 'constant') */ 220 break; 221 default: 222 /* make sure we dont leak kernel information to user */ 223 CLEAR_A(); /* A = 0 */ 224 } 225 226 for (i = 0; i < flen; i++) { 227 unsigned int K = filter[i].k; 228 229 switch (filter[i].code) { 230 case BPF_S_ALU_ADD_X: /* A += X; */ 231 seen |= SEEN_XREG; 232 EMIT2(0x01, 0xd8); /* add %ebx,%eax */ 233 break; 234 case BPF_S_ALU_ADD_K: /* A += K; */ 235 if (!K) 236 break; 237 if (is_imm8(K)) 238 EMIT3(0x83, 0xc0, K); /* add imm8,%eax */ 239 else 240 EMIT1_off32(0x05, K); /* add imm32,%eax */ 241 break; 242 case BPF_S_ALU_SUB_X: /* A -= X; */ 243 seen |= SEEN_XREG; 244 EMIT2(0x29, 0xd8); /* sub %ebx,%eax */ 245 break; 246 case BPF_S_ALU_SUB_K: /* A -= K */ 247 if (!K) 248 break; 249 if (is_imm8(K)) 250 EMIT3(0x83, 0xe8, K); /* sub imm8,%eax */ 251 else 252 EMIT1_off32(0x2d, K); /* sub imm32,%eax */ 253 break; 254 case BPF_S_ALU_MUL_X: /* A *= X; */ 255 seen |= SEEN_XREG; 256 EMIT3(0x0f, 0xaf, 0xc3); /* imul %ebx,%eax */ 257 break; 258 case BPF_S_ALU_MUL_K: /* A *= K */ 259 if (is_imm8(K)) 260 EMIT3(0x6b, 0xc0, K); /* imul imm8,%eax,%eax */ 261 else { 262 EMIT2(0x69, 0xc0); /* imul imm32,%eax */ 263 EMIT(K, 4); 264 } 265 break; 266 case BPF_S_ALU_DIV_X: /* A /= X; */ 267 seen |= SEEN_XREG; 268 EMIT2(0x85, 0xdb); /* test %ebx,%ebx */ 269 if (pc_ret0 > 0) { 270 /* addrs[pc_ret0 - 1] is start address of target 271 * (addrs[i] - 4) is the address following this jmp 272 * ("xor %edx,%edx; div %ebx" being 4 bytes long) 273 */ 274 EMIT_COND_JMP(X86_JE, addrs[pc_ret0 - 1] - 275 (addrs[i] - 4)); 276 } else { 277 EMIT_COND_JMP(X86_JNE, 2 + 5); 278 CLEAR_A(); 279 EMIT1_off32(0xe9, cleanup_addr - (addrs[i] - 4)); /* jmp .+off32 */ 280 } 281 EMIT4(0x31, 0xd2, 0xf7, 0xf3); /* xor %edx,%edx; div %ebx */ 282 break; 283 case BPF_S_ALU_DIV_K: /* A = reciprocal_divide(A, K); */ 284 EMIT3(0x48, 0x69, 0xc0); /* imul imm32,%rax,%rax */ 285 EMIT(K, 4); 286 EMIT4(0x48, 0xc1, 0xe8, 0x20); /* shr $0x20,%rax */ 287 break; 288 case BPF_S_ALU_AND_X: 289 seen |= SEEN_XREG; 290 EMIT2(0x21, 0xd8); /* and %ebx,%eax */ 291 break; 292 case BPF_S_ALU_AND_K: 293 if (K >= 0xFFFFFF00) { 294 EMIT2(0x24, K & 0xFF); /* and imm8,%al */ 295 } else if (K >= 0xFFFF0000) { 296 EMIT2(0x66, 0x25); /* and imm16,%ax */ 297 EMIT(K, 2); 298 } else { 299 EMIT1_off32(0x25, K); /* and imm32,%eax */ 300 } 301 break; 302 case BPF_S_ALU_OR_X: 303 seen |= SEEN_XREG; 304 EMIT2(0x09, 0xd8); /* or %ebx,%eax */ 305 break; 306 case BPF_S_ALU_OR_K: 307 if (is_imm8(K)) 308 EMIT3(0x83, 0xc8, K); /* or imm8,%eax */ 309 else 310 EMIT1_off32(0x0d, K); /* or imm32,%eax */ 311 break; 312 case BPF_S_ANC_ALU_XOR_X: /* A ^= X; */ 313 seen |= SEEN_XREG; 314 EMIT2(0x31, 0xd8); /* xor %ebx,%eax */ 315 break; 316 case BPF_S_ALU_LSH_X: /* A <<= X; */ 317 seen |= SEEN_XREG; 318 EMIT4(0x89, 0xd9, 0xd3, 0xe0); /* mov %ebx,%ecx; shl %cl,%eax */ 319 break; 320 case BPF_S_ALU_LSH_K: 321 if (K == 0) 322 break; 323 else if (K == 1) 324 EMIT2(0xd1, 0xe0); /* shl %eax */ 325 else 326 EMIT3(0xc1, 0xe0, K); 327 break; 328 case BPF_S_ALU_RSH_X: /* A >>= X; */ 329 seen |= SEEN_XREG; 330 EMIT4(0x89, 0xd9, 0xd3, 0xe8); /* mov %ebx,%ecx; shr %cl,%eax */ 331 break; 332 case BPF_S_ALU_RSH_K: /* A >>= K; */ 333 if (K == 0) 334 break; 335 else if (K == 1) 336 EMIT2(0xd1, 0xe8); /* shr %eax */ 337 else 338 EMIT3(0xc1, 0xe8, K); 339 break; 340 case BPF_S_ALU_NEG: 341 EMIT2(0xf7, 0xd8); /* neg %eax */ 342 break; 343 case BPF_S_RET_K: 344 if (!K) { 345 if (pc_ret0 == -1) 346 pc_ret0 = i; 347 CLEAR_A(); 348 } else { 349 EMIT1_off32(0xb8, K); /* mov $imm32,%eax */ 350 } 351 /* fallinto */ 352 case BPF_S_RET_A: 353 if (seen_or_pass0) { 354 if (i != flen - 1) { 355 EMIT_JMP(cleanup_addr - addrs[i]); 356 break; 357 } 358 if (seen_or_pass0 & SEEN_XREG) 359 EMIT4(0x48, 0x8b, 0x5d, 0xf8); /* mov -8(%rbp),%rbx */ 360 EMIT1(0xc9); /* leaveq */ 361 } 362 EMIT1(0xc3); /* ret */ 363 break; 364 case BPF_S_MISC_TAX: /* X = A */ 365 seen |= SEEN_XREG; 366 EMIT2(0x89, 0xc3); /* mov %eax,%ebx */ 367 break; 368 case BPF_S_MISC_TXA: /* A = X */ 369 seen |= SEEN_XREG; 370 EMIT2(0x89, 0xd8); /* mov %ebx,%eax */ 371 break; 372 case BPF_S_LD_IMM: /* A = K */ 373 if (!K) 374 CLEAR_A(); 375 else 376 EMIT1_off32(0xb8, K); /* mov $imm32,%eax */ 377 break; 378 case BPF_S_LDX_IMM: /* X = K */ 379 seen |= SEEN_XREG; 380 if (!K) 381 CLEAR_X(); 382 else 383 EMIT1_off32(0xbb, K); /* mov $imm32,%ebx */ 384 break; 385 case BPF_S_LD_MEM: /* A = mem[K] : mov off8(%rbp),%eax */ 386 seen |= SEEN_MEM; 387 EMIT3(0x8b, 0x45, 0xf0 - K*4); 388 break; 389 case BPF_S_LDX_MEM: /* X = mem[K] : mov off8(%rbp),%ebx */ 390 seen |= SEEN_XREG | SEEN_MEM; 391 EMIT3(0x8b, 0x5d, 0xf0 - K*4); 392 break; 393 case BPF_S_ST: /* mem[K] = A : mov %eax,off8(%rbp) */ 394 seen |= SEEN_MEM; 395 EMIT3(0x89, 0x45, 0xf0 - K*4); 396 break; 397 case BPF_S_STX: /* mem[K] = X : mov %ebx,off8(%rbp) */ 398 seen |= SEEN_XREG | SEEN_MEM; 399 EMIT3(0x89, 0x5d, 0xf0 - K*4); 400 break; 401 case BPF_S_LD_W_LEN: /* A = skb->len; */ 402 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4); 403 if (is_imm8(offsetof(struct sk_buff, len))) 404 /* mov off8(%rdi),%eax */ 405 EMIT3(0x8b, 0x47, offsetof(struct sk_buff, len)); 406 else { 407 EMIT2(0x8b, 0x87); 408 EMIT(offsetof(struct sk_buff, len), 4); 409 } 410 break; 411 case BPF_S_LDX_W_LEN: /* X = skb->len; */ 412 seen |= SEEN_XREG; 413 if (is_imm8(offsetof(struct sk_buff, len))) 414 /* mov off8(%rdi),%ebx */ 415 EMIT3(0x8b, 0x5f, offsetof(struct sk_buff, len)); 416 else { 417 EMIT2(0x8b, 0x9f); 418 EMIT(offsetof(struct sk_buff, len), 4); 419 } 420 break; 421 case BPF_S_ANC_PROTOCOL: /* A = ntohs(skb->protocol); */ 422 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2); 423 if (is_imm8(offsetof(struct sk_buff, protocol))) { 424 /* movzwl off8(%rdi),%eax */ 425 EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, protocol)); 426 } else { 427 EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */ 428 EMIT(offsetof(struct sk_buff, protocol), 4); 429 } 430 EMIT2(0x86, 0xc4); /* ntohs() : xchg %al,%ah */ 431 break; 432 case BPF_S_ANC_IFINDEX: 433 if (is_imm8(offsetof(struct sk_buff, dev))) { 434 /* movq off8(%rdi),%rax */ 435 EMIT4(0x48, 0x8b, 0x47, offsetof(struct sk_buff, dev)); 436 } else { 437 EMIT3(0x48, 0x8b, 0x87); /* movq off32(%rdi),%rax */ 438 EMIT(offsetof(struct sk_buff, dev), 4); 439 } 440 EMIT3(0x48, 0x85, 0xc0); /* test %rax,%rax */ 441 EMIT_COND_JMP(X86_JE, cleanup_addr - (addrs[i] - 6)); 442 BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4); 443 EMIT2(0x8b, 0x80); /* mov off32(%rax),%eax */ 444 EMIT(offsetof(struct net_device, ifindex), 4); 445 break; 446 case BPF_S_ANC_MARK: 447 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4); 448 if (is_imm8(offsetof(struct sk_buff, mark))) { 449 /* mov off8(%rdi),%eax */ 450 EMIT3(0x8b, 0x47, offsetof(struct sk_buff, mark)); 451 } else { 452 EMIT2(0x8b, 0x87); 453 EMIT(offsetof(struct sk_buff, mark), 4); 454 } 455 break; 456 case BPF_S_ANC_RXHASH: 457 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, rxhash) != 4); 458 if (is_imm8(offsetof(struct sk_buff, rxhash))) { 459 /* mov off8(%rdi),%eax */ 460 EMIT3(0x8b, 0x47, offsetof(struct sk_buff, rxhash)); 461 } else { 462 EMIT2(0x8b, 0x87); 463 EMIT(offsetof(struct sk_buff, rxhash), 4); 464 } 465 break; 466 case BPF_S_ANC_QUEUE: 467 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, queue_mapping) != 2); 468 if (is_imm8(offsetof(struct sk_buff, queue_mapping))) { 469 /* movzwl off8(%rdi),%eax */ 470 EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, queue_mapping)); 471 } else { 472 EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */ 473 EMIT(offsetof(struct sk_buff, queue_mapping), 4); 474 } 475 break; 476 case BPF_S_ANC_CPU: 477 #ifdef CONFIG_SMP 478 EMIT4(0x65, 0x8b, 0x04, 0x25); /* mov %gs:off32,%eax */ 479 EMIT((u32)(unsigned long)&cpu_number, 4); /* A = smp_processor_id(); */ 480 #else 481 CLEAR_A(); 482 #endif 483 break; 484 case BPF_S_LD_W_ABS: 485 func = CHOOSE_LOAD_FUNC(K, sk_load_word); 486 common_load: seen |= SEEN_DATAREF; 487 t_offset = func - (image + addrs[i]); 488 EMIT1_off32(0xbe, K); /* mov imm32,%esi */ 489 EMIT1_off32(0xe8, t_offset); /* call */ 490 break; 491 case BPF_S_LD_H_ABS: 492 func = CHOOSE_LOAD_FUNC(K, sk_load_half); 493 goto common_load; 494 case BPF_S_LD_B_ABS: 495 func = CHOOSE_LOAD_FUNC(K, sk_load_byte); 496 goto common_load; 497 case BPF_S_LDX_B_MSH: 498 func = CHOOSE_LOAD_FUNC(K, sk_load_byte_msh); 499 seen |= SEEN_DATAREF | SEEN_XREG; 500 t_offset = func - (image + addrs[i]); 501 EMIT1_off32(0xbe, K); /* mov imm32,%esi */ 502 EMIT1_off32(0xe8, t_offset); /* call sk_load_byte_msh */ 503 break; 504 case BPF_S_LD_W_IND: 505 func = sk_load_word; 506 common_load_ind: seen |= SEEN_DATAREF | SEEN_XREG; 507 t_offset = func - (image + addrs[i]); 508 if (K) { 509 if (is_imm8(K)) { 510 EMIT3(0x8d, 0x73, K); /* lea imm8(%rbx), %esi */ 511 } else { 512 EMIT2(0x8d, 0xb3); /* lea imm32(%rbx),%esi */ 513 EMIT(K, 4); 514 } 515 } else { 516 EMIT2(0x89,0xde); /* mov %ebx,%esi */ 517 } 518 EMIT1_off32(0xe8, t_offset); /* call sk_load_xxx_ind */ 519 break; 520 case BPF_S_LD_H_IND: 521 func = sk_load_half; 522 goto common_load_ind; 523 case BPF_S_LD_B_IND: 524 func = sk_load_byte; 525 goto common_load_ind; 526 case BPF_S_JMP_JA: 527 t_offset = addrs[i + K] - addrs[i]; 528 EMIT_JMP(t_offset); 529 break; 530 COND_SEL(BPF_S_JMP_JGT_K, X86_JA, X86_JBE); 531 COND_SEL(BPF_S_JMP_JGE_K, X86_JAE, X86_JB); 532 COND_SEL(BPF_S_JMP_JEQ_K, X86_JE, X86_JNE); 533 COND_SEL(BPF_S_JMP_JSET_K,X86_JNE, X86_JE); 534 COND_SEL(BPF_S_JMP_JGT_X, X86_JA, X86_JBE); 535 COND_SEL(BPF_S_JMP_JGE_X, X86_JAE, X86_JB); 536 COND_SEL(BPF_S_JMP_JEQ_X, X86_JE, X86_JNE); 537 COND_SEL(BPF_S_JMP_JSET_X,X86_JNE, X86_JE); 538 539 cond_branch: f_offset = addrs[i + filter[i].jf] - addrs[i]; 540 t_offset = addrs[i + filter[i].jt] - addrs[i]; 541 542 /* same targets, can avoid doing the test :) */ 543 if (filter[i].jt == filter[i].jf) { 544 EMIT_JMP(t_offset); 545 break; 546 } 547 548 switch (filter[i].code) { 549 case BPF_S_JMP_JGT_X: 550 case BPF_S_JMP_JGE_X: 551 case BPF_S_JMP_JEQ_X: 552 seen |= SEEN_XREG; 553 EMIT2(0x39, 0xd8); /* cmp %ebx,%eax */ 554 break; 555 case BPF_S_JMP_JSET_X: 556 seen |= SEEN_XREG; 557 EMIT2(0x85, 0xd8); /* test %ebx,%eax */ 558 break; 559 case BPF_S_JMP_JEQ_K: 560 if (K == 0) { 561 EMIT2(0x85, 0xc0); /* test %eax,%eax */ 562 break; 563 } 564 case BPF_S_JMP_JGT_K: 565 case BPF_S_JMP_JGE_K: 566 if (K <= 127) 567 EMIT3(0x83, 0xf8, K); /* cmp imm8,%eax */ 568 else 569 EMIT1_off32(0x3d, K); /* cmp imm32,%eax */ 570 break; 571 case BPF_S_JMP_JSET_K: 572 if (K <= 0xFF) 573 EMIT2(0xa8, K); /* test imm8,%al */ 574 else if (!(K & 0xFFFF00FF)) 575 EMIT3(0xf6, 0xc4, K >> 8); /* test imm8,%ah */ 576 else if (K <= 0xFFFF) { 577 EMIT2(0x66, 0xa9); /* test imm16,%ax */ 578 EMIT(K, 2); 579 } else { 580 EMIT1_off32(0xa9, K); /* test imm32,%eax */ 581 } 582 break; 583 } 584 if (filter[i].jt != 0) { 585 if (filter[i].jf && f_offset) 586 t_offset += is_near(f_offset) ? 2 : 5; 587 EMIT_COND_JMP(t_op, t_offset); 588 if (filter[i].jf) 589 EMIT_JMP(f_offset); 590 break; 591 } 592 EMIT_COND_JMP(f_op, f_offset); 593 break; 594 default: 595 /* hmm, too complex filter, give up with jit compiler */ 596 goto out; 597 } 598 ilen = prog - temp; 599 if (image) { 600 if (unlikely(proglen + ilen > oldproglen)) { 601 pr_err("bpb_jit_compile fatal error\n"); 602 kfree(addrs); 603 module_free(NULL, image); 604 return; 605 } 606 memcpy(image + proglen, temp, ilen); 607 } 608 proglen += ilen; 609 addrs[i] = proglen; 610 prog = temp; 611 } 612 /* last bpf instruction is always a RET : 613 * use it to give the cleanup instruction(s) addr 614 */ 615 cleanup_addr = proglen - 1; /* ret */ 616 if (seen_or_pass0) 617 cleanup_addr -= 1; /* leaveq */ 618 if (seen_or_pass0 & SEEN_XREG) 619 cleanup_addr -= 4; /* mov -8(%rbp),%rbx */ 620 621 if (image) { 622 if (proglen != oldproglen) 623 pr_err("bpb_jit_compile proglen=%u != oldproglen=%u\n", proglen, oldproglen); 624 break; 625 } 626 if (proglen == oldproglen) { 627 image = module_alloc(max_t(unsigned int, 628 proglen, 629 sizeof(struct work_struct))); 630 if (!image) 631 goto out; 632 } 633 oldproglen = proglen; 634 } 635 if (bpf_jit_enable > 1) 636 pr_err("flen=%d proglen=%u pass=%d image=%p\n", 637 flen, proglen, pass, image); 638 639 if (image) { 640 if (bpf_jit_enable > 1) 641 print_hex_dump(KERN_ERR, "JIT code: ", DUMP_PREFIX_ADDRESS, 642 16, 1, image, proglen, false); 643 644 bpf_flush_icache(image, image + proglen); 645 646 fp->bpf_func = (void *)image; 647 } 648 out: 649 kfree(addrs); 650 return; 651 } 652 653 static void jit_free_defer(struct work_struct *arg) 654 { 655 module_free(NULL, arg); 656 } 657 658 /* run from softirq, we must use a work_struct to call 659 * module_free() from process context 660 */ 661 void bpf_jit_free(struct sk_filter *fp) 662 { 663 if (fp->bpf_func != sk_run_filter) { 664 struct work_struct *work = (struct work_struct *)fp->bpf_func; 665 666 INIT_WORK(work, jit_free_defer); 667 schedule_work(work); 668 } 669 } 670