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