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