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_MOD_X: /* A %= X; */ 284 seen |= SEEN_XREG; 285 EMIT2(0x85, 0xdb); /* test %ebx,%ebx */ 286 if (pc_ret0 > 0) { 287 /* addrs[pc_ret0 - 1] is start address of target 288 * (addrs[i] - 6) is the address following this jmp 289 * ("xor %edx,%edx; div %ebx;mov %edx,%eax" being 6 bytes long) 290 */ 291 EMIT_COND_JMP(X86_JE, addrs[pc_ret0 - 1] - 292 (addrs[i] - 6)); 293 } else { 294 EMIT_COND_JMP(X86_JNE, 2 + 5); 295 CLEAR_A(); 296 EMIT1_off32(0xe9, cleanup_addr - (addrs[i] - 6)); /* jmp .+off32 */ 297 } 298 EMIT2(0x31, 0xd2); /* xor %edx,%edx */ 299 EMIT2(0xf7, 0xf3); /* div %ebx */ 300 EMIT2(0x89, 0xd0); /* mov %edx,%eax */ 301 break; 302 case BPF_S_ALU_MOD_K: /* A %= K; */ 303 EMIT2(0x31, 0xd2); /* xor %edx,%edx */ 304 EMIT1(0xb9);EMIT(K, 4); /* mov imm32,%ecx */ 305 EMIT2(0xf7, 0xf1); /* div %ecx */ 306 EMIT2(0x89, 0xd0); /* mov %edx,%eax */ 307 break; 308 case BPF_S_ALU_DIV_K: /* A = reciprocal_divide(A, K); */ 309 EMIT3(0x48, 0x69, 0xc0); /* imul imm32,%rax,%rax */ 310 EMIT(K, 4); 311 EMIT4(0x48, 0xc1, 0xe8, 0x20); /* shr $0x20,%rax */ 312 break; 313 case BPF_S_ALU_AND_X: 314 seen |= SEEN_XREG; 315 EMIT2(0x21, 0xd8); /* and %ebx,%eax */ 316 break; 317 case BPF_S_ALU_AND_K: 318 if (K >= 0xFFFFFF00) { 319 EMIT2(0x24, K & 0xFF); /* and imm8,%al */ 320 } else if (K >= 0xFFFF0000) { 321 EMIT2(0x66, 0x25); /* and imm16,%ax */ 322 EMIT(K, 2); 323 } else { 324 EMIT1_off32(0x25, K); /* and imm32,%eax */ 325 } 326 break; 327 case BPF_S_ALU_OR_X: 328 seen |= SEEN_XREG; 329 EMIT2(0x09, 0xd8); /* or %ebx,%eax */ 330 break; 331 case BPF_S_ALU_OR_K: 332 if (is_imm8(K)) 333 EMIT3(0x83, 0xc8, K); /* or imm8,%eax */ 334 else 335 EMIT1_off32(0x0d, K); /* or imm32,%eax */ 336 break; 337 case BPF_S_ANC_ALU_XOR_X: /* A ^= X; */ 338 case BPF_S_ALU_XOR_X: 339 seen |= SEEN_XREG; 340 EMIT2(0x31, 0xd8); /* xor %ebx,%eax */ 341 break; 342 case BPF_S_ALU_XOR_K: /* A ^= K; */ 343 if (K == 0) 344 break; 345 if (is_imm8(K)) 346 EMIT3(0x83, 0xf0, K); /* xor imm8,%eax */ 347 else 348 EMIT1_off32(0x35, K); /* xor imm32,%eax */ 349 break; 350 case BPF_S_ALU_LSH_X: /* A <<= X; */ 351 seen |= SEEN_XREG; 352 EMIT4(0x89, 0xd9, 0xd3, 0xe0); /* mov %ebx,%ecx; shl %cl,%eax */ 353 break; 354 case BPF_S_ALU_LSH_K: 355 if (K == 0) 356 break; 357 else if (K == 1) 358 EMIT2(0xd1, 0xe0); /* shl %eax */ 359 else 360 EMIT3(0xc1, 0xe0, K); 361 break; 362 case BPF_S_ALU_RSH_X: /* A >>= X; */ 363 seen |= SEEN_XREG; 364 EMIT4(0x89, 0xd9, 0xd3, 0xe8); /* mov %ebx,%ecx; shr %cl,%eax */ 365 break; 366 case BPF_S_ALU_RSH_K: /* A >>= K; */ 367 if (K == 0) 368 break; 369 else if (K == 1) 370 EMIT2(0xd1, 0xe8); /* shr %eax */ 371 else 372 EMIT3(0xc1, 0xe8, K); 373 break; 374 case BPF_S_ALU_NEG: 375 EMIT2(0xf7, 0xd8); /* neg %eax */ 376 break; 377 case BPF_S_RET_K: 378 if (!K) { 379 if (pc_ret0 == -1) 380 pc_ret0 = i; 381 CLEAR_A(); 382 } else { 383 EMIT1_off32(0xb8, K); /* mov $imm32,%eax */ 384 } 385 /* fallinto */ 386 case BPF_S_RET_A: 387 if (seen_or_pass0) { 388 if (i != flen - 1) { 389 EMIT_JMP(cleanup_addr - addrs[i]); 390 break; 391 } 392 if (seen_or_pass0 & SEEN_XREG) 393 EMIT4(0x48, 0x8b, 0x5d, 0xf8); /* mov -8(%rbp),%rbx */ 394 EMIT1(0xc9); /* leaveq */ 395 } 396 EMIT1(0xc3); /* ret */ 397 break; 398 case BPF_S_MISC_TAX: /* X = A */ 399 seen |= SEEN_XREG; 400 EMIT2(0x89, 0xc3); /* mov %eax,%ebx */ 401 break; 402 case BPF_S_MISC_TXA: /* A = X */ 403 seen |= SEEN_XREG; 404 EMIT2(0x89, 0xd8); /* mov %ebx,%eax */ 405 break; 406 case BPF_S_LD_IMM: /* A = K */ 407 if (!K) 408 CLEAR_A(); 409 else 410 EMIT1_off32(0xb8, K); /* mov $imm32,%eax */ 411 break; 412 case BPF_S_LDX_IMM: /* X = K */ 413 seen |= SEEN_XREG; 414 if (!K) 415 CLEAR_X(); 416 else 417 EMIT1_off32(0xbb, K); /* mov $imm32,%ebx */ 418 break; 419 case BPF_S_LD_MEM: /* A = mem[K] : mov off8(%rbp),%eax */ 420 seen |= SEEN_MEM; 421 EMIT3(0x8b, 0x45, 0xf0 - K*4); 422 break; 423 case BPF_S_LDX_MEM: /* X = mem[K] : mov off8(%rbp),%ebx */ 424 seen |= SEEN_XREG | SEEN_MEM; 425 EMIT3(0x8b, 0x5d, 0xf0 - K*4); 426 break; 427 case BPF_S_ST: /* mem[K] = A : mov %eax,off8(%rbp) */ 428 seen |= SEEN_MEM; 429 EMIT3(0x89, 0x45, 0xf0 - K*4); 430 break; 431 case BPF_S_STX: /* mem[K] = X : mov %ebx,off8(%rbp) */ 432 seen |= SEEN_XREG | SEEN_MEM; 433 EMIT3(0x89, 0x5d, 0xf0 - K*4); 434 break; 435 case BPF_S_LD_W_LEN: /* A = skb->len; */ 436 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4); 437 if (is_imm8(offsetof(struct sk_buff, len))) 438 /* mov off8(%rdi),%eax */ 439 EMIT3(0x8b, 0x47, offsetof(struct sk_buff, len)); 440 else { 441 EMIT2(0x8b, 0x87); 442 EMIT(offsetof(struct sk_buff, len), 4); 443 } 444 break; 445 case BPF_S_LDX_W_LEN: /* X = skb->len; */ 446 seen |= SEEN_XREG; 447 if (is_imm8(offsetof(struct sk_buff, len))) 448 /* mov off8(%rdi),%ebx */ 449 EMIT3(0x8b, 0x5f, offsetof(struct sk_buff, len)); 450 else { 451 EMIT2(0x8b, 0x9f); 452 EMIT(offsetof(struct sk_buff, len), 4); 453 } 454 break; 455 case BPF_S_ANC_PROTOCOL: /* A = ntohs(skb->protocol); */ 456 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2); 457 if (is_imm8(offsetof(struct sk_buff, protocol))) { 458 /* movzwl off8(%rdi),%eax */ 459 EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, protocol)); 460 } else { 461 EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */ 462 EMIT(offsetof(struct sk_buff, protocol), 4); 463 } 464 EMIT2(0x86, 0xc4); /* ntohs() : xchg %al,%ah */ 465 break; 466 case BPF_S_ANC_IFINDEX: 467 if (is_imm8(offsetof(struct sk_buff, dev))) { 468 /* movq off8(%rdi),%rax */ 469 EMIT4(0x48, 0x8b, 0x47, offsetof(struct sk_buff, dev)); 470 } else { 471 EMIT3(0x48, 0x8b, 0x87); /* movq off32(%rdi),%rax */ 472 EMIT(offsetof(struct sk_buff, dev), 4); 473 } 474 EMIT3(0x48, 0x85, 0xc0); /* test %rax,%rax */ 475 EMIT_COND_JMP(X86_JE, cleanup_addr - (addrs[i] - 6)); 476 BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4); 477 EMIT2(0x8b, 0x80); /* mov off32(%rax),%eax */ 478 EMIT(offsetof(struct net_device, ifindex), 4); 479 break; 480 case BPF_S_ANC_MARK: 481 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4); 482 if (is_imm8(offsetof(struct sk_buff, mark))) { 483 /* mov off8(%rdi),%eax */ 484 EMIT3(0x8b, 0x47, offsetof(struct sk_buff, mark)); 485 } else { 486 EMIT2(0x8b, 0x87); 487 EMIT(offsetof(struct sk_buff, mark), 4); 488 } 489 break; 490 case BPF_S_ANC_RXHASH: 491 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, rxhash) != 4); 492 if (is_imm8(offsetof(struct sk_buff, rxhash))) { 493 /* mov off8(%rdi),%eax */ 494 EMIT3(0x8b, 0x47, offsetof(struct sk_buff, rxhash)); 495 } else { 496 EMIT2(0x8b, 0x87); 497 EMIT(offsetof(struct sk_buff, rxhash), 4); 498 } 499 break; 500 case BPF_S_ANC_QUEUE: 501 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, queue_mapping) != 2); 502 if (is_imm8(offsetof(struct sk_buff, queue_mapping))) { 503 /* movzwl off8(%rdi),%eax */ 504 EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, queue_mapping)); 505 } else { 506 EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */ 507 EMIT(offsetof(struct sk_buff, queue_mapping), 4); 508 } 509 break; 510 case BPF_S_ANC_CPU: 511 #ifdef CONFIG_SMP 512 EMIT4(0x65, 0x8b, 0x04, 0x25); /* mov %gs:off32,%eax */ 513 EMIT((u32)(unsigned long)&cpu_number, 4); /* A = smp_processor_id(); */ 514 #else 515 CLEAR_A(); 516 #endif 517 break; 518 case BPF_S_LD_W_ABS: 519 func = CHOOSE_LOAD_FUNC(K, sk_load_word); 520 common_load: seen |= SEEN_DATAREF; 521 t_offset = func - (image + addrs[i]); 522 EMIT1_off32(0xbe, K); /* mov imm32,%esi */ 523 EMIT1_off32(0xe8, t_offset); /* call */ 524 break; 525 case BPF_S_LD_H_ABS: 526 func = CHOOSE_LOAD_FUNC(K, sk_load_half); 527 goto common_load; 528 case BPF_S_LD_B_ABS: 529 func = CHOOSE_LOAD_FUNC(K, sk_load_byte); 530 goto common_load; 531 case BPF_S_LDX_B_MSH: 532 func = CHOOSE_LOAD_FUNC(K, sk_load_byte_msh); 533 seen |= SEEN_DATAREF | SEEN_XREG; 534 t_offset = func - (image + addrs[i]); 535 EMIT1_off32(0xbe, K); /* mov imm32,%esi */ 536 EMIT1_off32(0xe8, t_offset); /* call sk_load_byte_msh */ 537 break; 538 case BPF_S_LD_W_IND: 539 func = sk_load_word; 540 common_load_ind: seen |= SEEN_DATAREF | SEEN_XREG; 541 t_offset = func - (image + addrs[i]); 542 if (K) { 543 if (is_imm8(K)) { 544 EMIT3(0x8d, 0x73, K); /* lea imm8(%rbx), %esi */ 545 } else { 546 EMIT2(0x8d, 0xb3); /* lea imm32(%rbx),%esi */ 547 EMIT(K, 4); 548 } 549 } else { 550 EMIT2(0x89,0xde); /* mov %ebx,%esi */ 551 } 552 EMIT1_off32(0xe8, t_offset); /* call sk_load_xxx_ind */ 553 break; 554 case BPF_S_LD_H_IND: 555 func = sk_load_half; 556 goto common_load_ind; 557 case BPF_S_LD_B_IND: 558 func = sk_load_byte; 559 goto common_load_ind; 560 case BPF_S_JMP_JA: 561 t_offset = addrs[i + K] - addrs[i]; 562 EMIT_JMP(t_offset); 563 break; 564 COND_SEL(BPF_S_JMP_JGT_K, X86_JA, X86_JBE); 565 COND_SEL(BPF_S_JMP_JGE_K, X86_JAE, X86_JB); 566 COND_SEL(BPF_S_JMP_JEQ_K, X86_JE, X86_JNE); 567 COND_SEL(BPF_S_JMP_JSET_K,X86_JNE, X86_JE); 568 COND_SEL(BPF_S_JMP_JGT_X, X86_JA, X86_JBE); 569 COND_SEL(BPF_S_JMP_JGE_X, X86_JAE, X86_JB); 570 COND_SEL(BPF_S_JMP_JEQ_X, X86_JE, X86_JNE); 571 COND_SEL(BPF_S_JMP_JSET_X,X86_JNE, X86_JE); 572 573 cond_branch: f_offset = addrs[i + filter[i].jf] - addrs[i]; 574 t_offset = addrs[i + filter[i].jt] - addrs[i]; 575 576 /* same targets, can avoid doing the test :) */ 577 if (filter[i].jt == filter[i].jf) { 578 EMIT_JMP(t_offset); 579 break; 580 } 581 582 switch (filter[i].code) { 583 case BPF_S_JMP_JGT_X: 584 case BPF_S_JMP_JGE_X: 585 case BPF_S_JMP_JEQ_X: 586 seen |= SEEN_XREG; 587 EMIT2(0x39, 0xd8); /* cmp %ebx,%eax */ 588 break; 589 case BPF_S_JMP_JSET_X: 590 seen |= SEEN_XREG; 591 EMIT2(0x85, 0xd8); /* test %ebx,%eax */ 592 break; 593 case BPF_S_JMP_JEQ_K: 594 if (K == 0) { 595 EMIT2(0x85, 0xc0); /* test %eax,%eax */ 596 break; 597 } 598 case BPF_S_JMP_JGT_K: 599 case BPF_S_JMP_JGE_K: 600 if (K <= 127) 601 EMIT3(0x83, 0xf8, K); /* cmp imm8,%eax */ 602 else 603 EMIT1_off32(0x3d, K); /* cmp imm32,%eax */ 604 break; 605 case BPF_S_JMP_JSET_K: 606 if (K <= 0xFF) 607 EMIT2(0xa8, K); /* test imm8,%al */ 608 else if (!(K & 0xFFFF00FF)) 609 EMIT3(0xf6, 0xc4, K >> 8); /* test imm8,%ah */ 610 else if (K <= 0xFFFF) { 611 EMIT2(0x66, 0xa9); /* test imm16,%ax */ 612 EMIT(K, 2); 613 } else { 614 EMIT1_off32(0xa9, K); /* test imm32,%eax */ 615 } 616 break; 617 } 618 if (filter[i].jt != 0) { 619 if (filter[i].jf && f_offset) 620 t_offset += is_near(f_offset) ? 2 : 5; 621 EMIT_COND_JMP(t_op, t_offset); 622 if (filter[i].jf) 623 EMIT_JMP(f_offset); 624 break; 625 } 626 EMIT_COND_JMP(f_op, f_offset); 627 break; 628 default: 629 /* hmm, too complex filter, give up with jit compiler */ 630 goto out; 631 } 632 ilen = prog - temp; 633 if (image) { 634 if (unlikely(proglen + ilen > oldproglen)) { 635 pr_err("bpb_jit_compile fatal error\n"); 636 kfree(addrs); 637 module_free(NULL, image); 638 return; 639 } 640 memcpy(image + proglen, temp, ilen); 641 } 642 proglen += ilen; 643 addrs[i] = proglen; 644 prog = temp; 645 } 646 /* last bpf instruction is always a RET : 647 * use it to give the cleanup instruction(s) addr 648 */ 649 cleanup_addr = proglen - 1; /* ret */ 650 if (seen_or_pass0) 651 cleanup_addr -= 1; /* leaveq */ 652 if (seen_or_pass0 & SEEN_XREG) 653 cleanup_addr -= 4; /* mov -8(%rbp),%rbx */ 654 655 if (image) { 656 if (proglen != oldproglen) 657 pr_err("bpb_jit_compile proglen=%u != oldproglen=%u\n", proglen, oldproglen); 658 break; 659 } 660 if (proglen == oldproglen) { 661 image = module_alloc(max_t(unsigned int, 662 proglen, 663 sizeof(struct work_struct))); 664 if (!image) 665 goto out; 666 } 667 oldproglen = proglen; 668 } 669 if (bpf_jit_enable > 1) 670 pr_err("flen=%d proglen=%u pass=%d image=%p\n", 671 flen, proglen, pass, image); 672 673 if (image) { 674 if (bpf_jit_enable > 1) 675 print_hex_dump(KERN_ERR, "JIT code: ", DUMP_PREFIX_ADDRESS, 676 16, 1, image, proglen, false); 677 678 bpf_flush_icache(image, image + proglen); 679 680 fp->bpf_func = (void *)image; 681 } 682 out: 683 kfree(addrs); 684 return; 685 } 686 687 static void jit_free_defer(struct work_struct *arg) 688 { 689 module_free(NULL, arg); 690 } 691 692 /* run from softirq, we must use a work_struct to call 693 * module_free() from process context 694 */ 695 void bpf_jit_free(struct sk_filter *fp) 696 { 697 if (fp->bpf_func != sk_run_filter) { 698 struct work_struct *work = (struct work_struct *)fp->bpf_func; 699 700 INIT_WORK(work, jit_free_defer); 701 schedule_work(work); 702 } 703 } 704