1 /* bpf_jit_comp.c : BPF JIT compiler 2 * 3 * Copyright (C) 2011-2013 Eric Dumazet (eric.dumazet@gmail.com) 4 * Internal BPF Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; version 2 9 * of the License. 10 */ 11 #include <linux/netdevice.h> 12 #include <linux/filter.h> 13 #include <linux/if_vlan.h> 14 #include <asm/cacheflush.h> 15 16 int bpf_jit_enable __read_mostly; 17 18 /* 19 * assembly code in arch/x86/net/bpf_jit.S 20 */ 21 extern u8 sk_load_word[], sk_load_half[], sk_load_byte[]; 22 extern u8 sk_load_word_positive_offset[], sk_load_half_positive_offset[]; 23 extern u8 sk_load_byte_positive_offset[]; 24 extern u8 sk_load_word_negative_offset[], sk_load_half_negative_offset[]; 25 extern u8 sk_load_byte_negative_offset[]; 26 27 static u8 *emit_code(u8 *ptr, u32 bytes, unsigned int len) 28 { 29 if (len == 1) 30 *ptr = bytes; 31 else if (len == 2) 32 *(u16 *)ptr = bytes; 33 else { 34 *(u32 *)ptr = bytes; 35 barrier(); 36 } 37 return ptr + len; 38 } 39 40 #define EMIT(bytes, len) do { prog = emit_code(prog, bytes, len); } while (0) 41 42 #define EMIT1(b1) EMIT(b1, 1) 43 #define EMIT2(b1, b2) EMIT((b1) + ((b2) << 8), 2) 44 #define EMIT3(b1, b2, b3) EMIT((b1) + ((b2) << 8) + ((b3) << 16), 3) 45 #define EMIT4(b1, b2, b3, b4) EMIT((b1) + ((b2) << 8) + ((b3) << 16) + ((b4) << 24), 4) 46 #define EMIT1_off32(b1, off) \ 47 do {EMIT1(b1); EMIT(off, 4); } while (0) 48 #define EMIT2_off32(b1, b2, off) \ 49 do {EMIT2(b1, b2); EMIT(off, 4); } while (0) 50 #define EMIT3_off32(b1, b2, b3, off) \ 51 do {EMIT3(b1, b2, b3); EMIT(off, 4); } while (0) 52 #define EMIT4_off32(b1, b2, b3, b4, off) \ 53 do {EMIT4(b1, b2, b3, b4); EMIT(off, 4); } while (0) 54 55 static bool is_imm8(int value) 56 { 57 return value <= 127 && value >= -128; 58 } 59 60 static bool is_simm32(s64 value) 61 { 62 return value == (s64) (s32) value; 63 } 64 65 /* mov dst, src */ 66 #define EMIT_mov(DST, SRC) \ 67 do {if (DST != SRC) \ 68 EMIT3(add_2mod(0x48, DST, SRC), 0x89, add_2reg(0xC0, DST, SRC)); \ 69 } while (0) 70 71 static int bpf_size_to_x86_bytes(int bpf_size) 72 { 73 if (bpf_size == BPF_W) 74 return 4; 75 else if (bpf_size == BPF_H) 76 return 2; 77 else if (bpf_size == BPF_B) 78 return 1; 79 else if (bpf_size == BPF_DW) 80 return 4; /* imm32 */ 81 else 82 return 0; 83 } 84 85 /* list of x86 cond jumps opcodes (. + s8) 86 * Add 0x10 (and an extra 0x0f) to generate far jumps (. + s32) 87 */ 88 #define X86_JB 0x72 89 #define X86_JAE 0x73 90 #define X86_JE 0x74 91 #define X86_JNE 0x75 92 #define X86_JBE 0x76 93 #define X86_JA 0x77 94 #define X86_JGE 0x7D 95 #define X86_JG 0x7F 96 97 static void bpf_flush_icache(void *start, void *end) 98 { 99 mm_segment_t old_fs = get_fs(); 100 101 set_fs(KERNEL_DS); 102 smp_wmb(); 103 flush_icache_range((unsigned long)start, (unsigned long)end); 104 set_fs(old_fs); 105 } 106 107 #define CHOOSE_LOAD_FUNC(K, func) \ 108 ((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative_offset : func) : func##_positive_offset) 109 110 /* pick a register outside of BPF range for JIT internal work */ 111 #define AUX_REG (MAX_BPF_REG + 1) 112 113 /* the following table maps BPF registers to x64 registers. 114 * x64 register r12 is unused, since if used as base address register 115 * in load/store instructions, it always needs an extra byte of encoding 116 */ 117 static const int reg2hex[] = { 118 [BPF_REG_0] = 0, /* rax */ 119 [BPF_REG_1] = 7, /* rdi */ 120 [BPF_REG_2] = 6, /* rsi */ 121 [BPF_REG_3] = 2, /* rdx */ 122 [BPF_REG_4] = 1, /* rcx */ 123 [BPF_REG_5] = 0, /* r8 */ 124 [BPF_REG_6] = 3, /* rbx callee saved */ 125 [BPF_REG_7] = 5, /* r13 callee saved */ 126 [BPF_REG_8] = 6, /* r14 callee saved */ 127 [BPF_REG_9] = 7, /* r15 callee saved */ 128 [BPF_REG_FP] = 5, /* rbp readonly */ 129 [AUX_REG] = 3, /* r11 temp register */ 130 }; 131 132 /* is_ereg() == true if BPF register 'reg' maps to x64 r8..r15 133 * which need extra byte of encoding. 134 * rax,rcx,...,rbp have simpler encoding 135 */ 136 static bool is_ereg(u32 reg) 137 { 138 return (1 << reg) & (BIT(BPF_REG_5) | 139 BIT(AUX_REG) | 140 BIT(BPF_REG_7) | 141 BIT(BPF_REG_8) | 142 BIT(BPF_REG_9)); 143 } 144 145 /* add modifiers if 'reg' maps to x64 registers r8..r15 */ 146 static u8 add_1mod(u8 byte, u32 reg) 147 { 148 if (is_ereg(reg)) 149 byte |= 1; 150 return byte; 151 } 152 153 static u8 add_2mod(u8 byte, u32 r1, u32 r2) 154 { 155 if (is_ereg(r1)) 156 byte |= 1; 157 if (is_ereg(r2)) 158 byte |= 4; 159 return byte; 160 } 161 162 /* encode 'dst_reg' register into x64 opcode 'byte' */ 163 static u8 add_1reg(u8 byte, u32 dst_reg) 164 { 165 return byte + reg2hex[dst_reg]; 166 } 167 168 /* encode 'dst_reg' and 'src_reg' registers into x64 opcode 'byte' */ 169 static u8 add_2reg(u8 byte, u32 dst_reg, u32 src_reg) 170 { 171 return byte + reg2hex[dst_reg] + (reg2hex[src_reg] << 3); 172 } 173 174 static void jit_fill_hole(void *area, unsigned int size) 175 { 176 /* fill whole space with int3 instructions */ 177 memset(area, 0xcc, size); 178 } 179 180 struct jit_context { 181 int cleanup_addr; /* epilogue code offset */ 182 bool seen_ld_abs; 183 }; 184 185 /* maximum number of bytes emitted while JITing one eBPF insn */ 186 #define BPF_MAX_INSN_SIZE 128 187 #define BPF_INSN_SAFETY 64 188 189 static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, 190 int oldproglen, struct jit_context *ctx) 191 { 192 struct bpf_insn *insn = bpf_prog->insnsi; 193 int insn_cnt = bpf_prog->len; 194 bool seen_ld_abs = ctx->seen_ld_abs | (oldproglen == 0); 195 bool seen_exit = false; 196 u8 temp[BPF_MAX_INSN_SIZE + BPF_INSN_SAFETY]; 197 int i; 198 int proglen = 0; 199 u8 *prog = temp; 200 int stacksize = MAX_BPF_STACK + 201 32 /* space for rbx, r13, r14, r15 */ + 202 8 /* space for skb_copy_bits() buffer */; 203 204 EMIT1(0x55); /* push rbp */ 205 EMIT3(0x48, 0x89, 0xE5); /* mov rbp,rsp */ 206 207 /* sub rsp, stacksize */ 208 EMIT3_off32(0x48, 0x81, 0xEC, stacksize); 209 210 /* all classic BPF filters use R6(rbx) save it */ 211 212 /* mov qword ptr [rbp-X],rbx */ 213 EMIT3_off32(0x48, 0x89, 0x9D, -stacksize); 214 215 /* bpf_convert_filter() maps classic BPF register X to R7 and uses R8 216 * as temporary, so all tcpdump filters need to spill/fill R7(r13) and 217 * R8(r14). R9(r15) spill could be made conditional, but there is only 218 * one 'bpf_error' return path out of helper functions inside bpf_jit.S 219 * The overhead of extra spill is negligible for any filter other 220 * than synthetic ones. Therefore not worth adding complexity. 221 */ 222 223 /* mov qword ptr [rbp-X],r13 */ 224 EMIT3_off32(0x4C, 0x89, 0xAD, -stacksize + 8); 225 /* mov qword ptr [rbp-X],r14 */ 226 EMIT3_off32(0x4C, 0x89, 0xB5, -stacksize + 16); 227 /* mov qword ptr [rbp-X],r15 */ 228 EMIT3_off32(0x4C, 0x89, 0xBD, -stacksize + 24); 229 230 /* clear A and X registers */ 231 EMIT2(0x31, 0xc0); /* xor eax, eax */ 232 EMIT3(0x4D, 0x31, 0xED); /* xor r13, r13 */ 233 234 if (seen_ld_abs) { 235 /* r9d : skb->len - skb->data_len (headlen) 236 * r10 : skb->data 237 */ 238 if (is_imm8(offsetof(struct sk_buff, len))) 239 /* mov %r9d, off8(%rdi) */ 240 EMIT4(0x44, 0x8b, 0x4f, 241 offsetof(struct sk_buff, len)); 242 else 243 /* mov %r9d, off32(%rdi) */ 244 EMIT3_off32(0x44, 0x8b, 0x8f, 245 offsetof(struct sk_buff, len)); 246 247 if (is_imm8(offsetof(struct sk_buff, data_len))) 248 /* sub %r9d, off8(%rdi) */ 249 EMIT4(0x44, 0x2b, 0x4f, 250 offsetof(struct sk_buff, data_len)); 251 else 252 EMIT3_off32(0x44, 0x2b, 0x8f, 253 offsetof(struct sk_buff, data_len)); 254 255 if (is_imm8(offsetof(struct sk_buff, data))) 256 /* mov %r10, off8(%rdi) */ 257 EMIT4(0x4c, 0x8b, 0x57, 258 offsetof(struct sk_buff, data)); 259 else 260 /* mov %r10, off32(%rdi) */ 261 EMIT3_off32(0x4c, 0x8b, 0x97, 262 offsetof(struct sk_buff, data)); 263 } 264 265 for (i = 0; i < insn_cnt; i++, insn++) { 266 const s32 imm32 = insn->imm; 267 u32 dst_reg = insn->dst_reg; 268 u32 src_reg = insn->src_reg; 269 u8 b1 = 0, b2 = 0, b3 = 0; 270 s64 jmp_offset; 271 u8 jmp_cond; 272 int ilen; 273 u8 *func; 274 275 switch (insn->code) { 276 /* ALU */ 277 case BPF_ALU | BPF_ADD | BPF_X: 278 case BPF_ALU | BPF_SUB | BPF_X: 279 case BPF_ALU | BPF_AND | BPF_X: 280 case BPF_ALU | BPF_OR | BPF_X: 281 case BPF_ALU | BPF_XOR | BPF_X: 282 case BPF_ALU64 | BPF_ADD | BPF_X: 283 case BPF_ALU64 | BPF_SUB | BPF_X: 284 case BPF_ALU64 | BPF_AND | BPF_X: 285 case BPF_ALU64 | BPF_OR | BPF_X: 286 case BPF_ALU64 | BPF_XOR | BPF_X: 287 switch (BPF_OP(insn->code)) { 288 case BPF_ADD: b2 = 0x01; break; 289 case BPF_SUB: b2 = 0x29; break; 290 case BPF_AND: b2 = 0x21; break; 291 case BPF_OR: b2 = 0x09; break; 292 case BPF_XOR: b2 = 0x31; break; 293 } 294 if (BPF_CLASS(insn->code) == BPF_ALU64) 295 EMIT1(add_2mod(0x48, dst_reg, src_reg)); 296 else if (is_ereg(dst_reg) || is_ereg(src_reg)) 297 EMIT1(add_2mod(0x40, dst_reg, src_reg)); 298 EMIT2(b2, add_2reg(0xC0, dst_reg, src_reg)); 299 break; 300 301 /* mov dst, src */ 302 case BPF_ALU64 | BPF_MOV | BPF_X: 303 EMIT_mov(dst_reg, src_reg); 304 break; 305 306 /* mov32 dst, src */ 307 case BPF_ALU | BPF_MOV | BPF_X: 308 if (is_ereg(dst_reg) || is_ereg(src_reg)) 309 EMIT1(add_2mod(0x40, dst_reg, src_reg)); 310 EMIT2(0x89, add_2reg(0xC0, dst_reg, src_reg)); 311 break; 312 313 /* neg dst */ 314 case BPF_ALU | BPF_NEG: 315 case BPF_ALU64 | BPF_NEG: 316 if (BPF_CLASS(insn->code) == BPF_ALU64) 317 EMIT1(add_1mod(0x48, dst_reg)); 318 else if (is_ereg(dst_reg)) 319 EMIT1(add_1mod(0x40, dst_reg)); 320 EMIT2(0xF7, add_1reg(0xD8, dst_reg)); 321 break; 322 323 case BPF_ALU | BPF_ADD | BPF_K: 324 case BPF_ALU | BPF_SUB | BPF_K: 325 case BPF_ALU | BPF_AND | BPF_K: 326 case BPF_ALU | BPF_OR | BPF_K: 327 case BPF_ALU | BPF_XOR | BPF_K: 328 case BPF_ALU64 | BPF_ADD | BPF_K: 329 case BPF_ALU64 | BPF_SUB | BPF_K: 330 case BPF_ALU64 | BPF_AND | BPF_K: 331 case BPF_ALU64 | BPF_OR | BPF_K: 332 case BPF_ALU64 | BPF_XOR | BPF_K: 333 if (BPF_CLASS(insn->code) == BPF_ALU64) 334 EMIT1(add_1mod(0x48, dst_reg)); 335 else if (is_ereg(dst_reg)) 336 EMIT1(add_1mod(0x40, dst_reg)); 337 338 switch (BPF_OP(insn->code)) { 339 case BPF_ADD: b3 = 0xC0; break; 340 case BPF_SUB: b3 = 0xE8; break; 341 case BPF_AND: b3 = 0xE0; break; 342 case BPF_OR: b3 = 0xC8; break; 343 case BPF_XOR: b3 = 0xF0; break; 344 } 345 346 if (is_imm8(imm32)) 347 EMIT3(0x83, add_1reg(b3, dst_reg), imm32); 348 else 349 EMIT2_off32(0x81, add_1reg(b3, dst_reg), imm32); 350 break; 351 352 case BPF_ALU64 | BPF_MOV | BPF_K: 353 /* optimization: if imm32 is positive, 354 * use 'mov eax, imm32' (which zero-extends imm32) 355 * to save 2 bytes 356 */ 357 if (imm32 < 0) { 358 /* 'mov rax, imm32' sign extends imm32 */ 359 b1 = add_1mod(0x48, dst_reg); 360 b2 = 0xC7; 361 b3 = 0xC0; 362 EMIT3_off32(b1, b2, add_1reg(b3, dst_reg), imm32); 363 break; 364 } 365 366 case BPF_ALU | BPF_MOV | BPF_K: 367 /* mov %eax, imm32 */ 368 if (is_ereg(dst_reg)) 369 EMIT1(add_1mod(0x40, dst_reg)); 370 EMIT1_off32(add_1reg(0xB8, dst_reg), imm32); 371 break; 372 373 case BPF_LD | BPF_IMM | BPF_DW: 374 if (insn[1].code != 0 || insn[1].src_reg != 0 || 375 insn[1].dst_reg != 0 || insn[1].off != 0) { 376 /* verifier must catch invalid insns */ 377 pr_err("invalid BPF_LD_IMM64 insn\n"); 378 return -EINVAL; 379 } 380 381 /* movabsq %rax, imm64 */ 382 EMIT2(add_1mod(0x48, dst_reg), add_1reg(0xB8, dst_reg)); 383 EMIT(insn[0].imm, 4); 384 EMIT(insn[1].imm, 4); 385 386 insn++; 387 i++; 388 break; 389 390 /* dst %= src, dst /= src, dst %= imm32, dst /= imm32 */ 391 case BPF_ALU | BPF_MOD | BPF_X: 392 case BPF_ALU | BPF_DIV | BPF_X: 393 case BPF_ALU | BPF_MOD | BPF_K: 394 case BPF_ALU | BPF_DIV | BPF_K: 395 case BPF_ALU64 | BPF_MOD | BPF_X: 396 case BPF_ALU64 | BPF_DIV | BPF_X: 397 case BPF_ALU64 | BPF_MOD | BPF_K: 398 case BPF_ALU64 | BPF_DIV | BPF_K: 399 EMIT1(0x50); /* push rax */ 400 EMIT1(0x52); /* push rdx */ 401 402 if (BPF_SRC(insn->code) == BPF_X) 403 /* mov r11, src_reg */ 404 EMIT_mov(AUX_REG, src_reg); 405 else 406 /* mov r11, imm32 */ 407 EMIT3_off32(0x49, 0xC7, 0xC3, imm32); 408 409 /* mov rax, dst_reg */ 410 EMIT_mov(BPF_REG_0, dst_reg); 411 412 /* xor edx, edx 413 * equivalent to 'xor rdx, rdx', but one byte less 414 */ 415 EMIT2(0x31, 0xd2); 416 417 if (BPF_SRC(insn->code) == BPF_X) { 418 /* if (src_reg == 0) return 0 */ 419 420 /* cmp r11, 0 */ 421 EMIT4(0x49, 0x83, 0xFB, 0x00); 422 423 /* jne .+9 (skip over pop, pop, xor and jmp) */ 424 EMIT2(X86_JNE, 1 + 1 + 2 + 5); 425 EMIT1(0x5A); /* pop rdx */ 426 EMIT1(0x58); /* pop rax */ 427 EMIT2(0x31, 0xc0); /* xor eax, eax */ 428 429 /* jmp cleanup_addr 430 * addrs[i] - 11, because there are 11 bytes 431 * after this insn: div, mov, pop, pop, mov 432 */ 433 jmp_offset = ctx->cleanup_addr - (addrs[i] - 11); 434 EMIT1_off32(0xE9, jmp_offset); 435 } 436 437 if (BPF_CLASS(insn->code) == BPF_ALU64) 438 /* div r11 */ 439 EMIT3(0x49, 0xF7, 0xF3); 440 else 441 /* div r11d */ 442 EMIT3(0x41, 0xF7, 0xF3); 443 444 if (BPF_OP(insn->code) == BPF_MOD) 445 /* mov r11, rdx */ 446 EMIT3(0x49, 0x89, 0xD3); 447 else 448 /* mov r11, rax */ 449 EMIT3(0x49, 0x89, 0xC3); 450 451 EMIT1(0x5A); /* pop rdx */ 452 EMIT1(0x58); /* pop rax */ 453 454 /* mov dst_reg, r11 */ 455 EMIT_mov(dst_reg, AUX_REG); 456 break; 457 458 case BPF_ALU | BPF_MUL | BPF_K: 459 case BPF_ALU | BPF_MUL | BPF_X: 460 case BPF_ALU64 | BPF_MUL | BPF_K: 461 case BPF_ALU64 | BPF_MUL | BPF_X: 462 EMIT1(0x50); /* push rax */ 463 EMIT1(0x52); /* push rdx */ 464 465 /* mov r11, dst_reg */ 466 EMIT_mov(AUX_REG, dst_reg); 467 468 if (BPF_SRC(insn->code) == BPF_X) 469 /* mov rax, src_reg */ 470 EMIT_mov(BPF_REG_0, src_reg); 471 else 472 /* mov rax, imm32 */ 473 EMIT3_off32(0x48, 0xC7, 0xC0, imm32); 474 475 if (BPF_CLASS(insn->code) == BPF_ALU64) 476 EMIT1(add_1mod(0x48, AUX_REG)); 477 else if (is_ereg(AUX_REG)) 478 EMIT1(add_1mod(0x40, AUX_REG)); 479 /* mul(q) r11 */ 480 EMIT2(0xF7, add_1reg(0xE0, AUX_REG)); 481 482 /* mov r11, rax */ 483 EMIT_mov(AUX_REG, BPF_REG_0); 484 485 EMIT1(0x5A); /* pop rdx */ 486 EMIT1(0x58); /* pop rax */ 487 488 /* mov dst_reg, r11 */ 489 EMIT_mov(dst_reg, AUX_REG); 490 break; 491 492 /* shifts */ 493 case BPF_ALU | BPF_LSH | BPF_K: 494 case BPF_ALU | BPF_RSH | BPF_K: 495 case BPF_ALU | BPF_ARSH | BPF_K: 496 case BPF_ALU64 | BPF_LSH | BPF_K: 497 case BPF_ALU64 | BPF_RSH | BPF_K: 498 case BPF_ALU64 | BPF_ARSH | BPF_K: 499 if (BPF_CLASS(insn->code) == BPF_ALU64) 500 EMIT1(add_1mod(0x48, dst_reg)); 501 else if (is_ereg(dst_reg)) 502 EMIT1(add_1mod(0x40, dst_reg)); 503 504 switch (BPF_OP(insn->code)) { 505 case BPF_LSH: b3 = 0xE0; break; 506 case BPF_RSH: b3 = 0xE8; break; 507 case BPF_ARSH: b3 = 0xF8; break; 508 } 509 EMIT3(0xC1, add_1reg(b3, dst_reg), imm32); 510 break; 511 512 case BPF_ALU | BPF_LSH | BPF_X: 513 case BPF_ALU | BPF_RSH | BPF_X: 514 case BPF_ALU | BPF_ARSH | BPF_X: 515 case BPF_ALU64 | BPF_LSH | BPF_X: 516 case BPF_ALU64 | BPF_RSH | BPF_X: 517 case BPF_ALU64 | BPF_ARSH | BPF_X: 518 519 /* check for bad case when dst_reg == rcx */ 520 if (dst_reg == BPF_REG_4) { 521 /* mov r11, dst_reg */ 522 EMIT_mov(AUX_REG, dst_reg); 523 dst_reg = AUX_REG; 524 } 525 526 if (src_reg != BPF_REG_4) { /* common case */ 527 EMIT1(0x51); /* push rcx */ 528 529 /* mov rcx, src_reg */ 530 EMIT_mov(BPF_REG_4, src_reg); 531 } 532 533 /* shl %rax, %cl | shr %rax, %cl | sar %rax, %cl */ 534 if (BPF_CLASS(insn->code) == BPF_ALU64) 535 EMIT1(add_1mod(0x48, dst_reg)); 536 else if (is_ereg(dst_reg)) 537 EMIT1(add_1mod(0x40, dst_reg)); 538 539 switch (BPF_OP(insn->code)) { 540 case BPF_LSH: b3 = 0xE0; break; 541 case BPF_RSH: b3 = 0xE8; break; 542 case BPF_ARSH: b3 = 0xF8; break; 543 } 544 EMIT2(0xD3, add_1reg(b3, dst_reg)); 545 546 if (src_reg != BPF_REG_4) 547 EMIT1(0x59); /* pop rcx */ 548 549 if (insn->dst_reg == BPF_REG_4) 550 /* mov dst_reg, r11 */ 551 EMIT_mov(insn->dst_reg, AUX_REG); 552 break; 553 554 case BPF_ALU | BPF_END | BPF_FROM_BE: 555 switch (imm32) { 556 case 16: 557 /* emit 'ror %ax, 8' to swap lower 2 bytes */ 558 EMIT1(0x66); 559 if (is_ereg(dst_reg)) 560 EMIT1(0x41); 561 EMIT3(0xC1, add_1reg(0xC8, dst_reg), 8); 562 563 /* emit 'movzwl eax, ax' */ 564 if (is_ereg(dst_reg)) 565 EMIT3(0x45, 0x0F, 0xB7); 566 else 567 EMIT2(0x0F, 0xB7); 568 EMIT1(add_2reg(0xC0, dst_reg, dst_reg)); 569 break; 570 case 32: 571 /* emit 'bswap eax' to swap lower 4 bytes */ 572 if (is_ereg(dst_reg)) 573 EMIT2(0x41, 0x0F); 574 else 575 EMIT1(0x0F); 576 EMIT1(add_1reg(0xC8, dst_reg)); 577 break; 578 case 64: 579 /* emit 'bswap rax' to swap 8 bytes */ 580 EMIT3(add_1mod(0x48, dst_reg), 0x0F, 581 add_1reg(0xC8, dst_reg)); 582 break; 583 } 584 break; 585 586 case BPF_ALU | BPF_END | BPF_FROM_LE: 587 switch (imm32) { 588 case 16: 589 /* emit 'movzwl eax, ax' to zero extend 16-bit 590 * into 64 bit 591 */ 592 if (is_ereg(dst_reg)) 593 EMIT3(0x45, 0x0F, 0xB7); 594 else 595 EMIT2(0x0F, 0xB7); 596 EMIT1(add_2reg(0xC0, dst_reg, dst_reg)); 597 break; 598 case 32: 599 /* emit 'mov eax, eax' to clear upper 32-bits */ 600 if (is_ereg(dst_reg)) 601 EMIT1(0x45); 602 EMIT2(0x89, add_2reg(0xC0, dst_reg, dst_reg)); 603 break; 604 case 64: 605 /* nop */ 606 break; 607 } 608 break; 609 610 /* ST: *(u8*)(dst_reg + off) = imm */ 611 case BPF_ST | BPF_MEM | BPF_B: 612 if (is_ereg(dst_reg)) 613 EMIT2(0x41, 0xC6); 614 else 615 EMIT1(0xC6); 616 goto st; 617 case BPF_ST | BPF_MEM | BPF_H: 618 if (is_ereg(dst_reg)) 619 EMIT3(0x66, 0x41, 0xC7); 620 else 621 EMIT2(0x66, 0xC7); 622 goto st; 623 case BPF_ST | BPF_MEM | BPF_W: 624 if (is_ereg(dst_reg)) 625 EMIT2(0x41, 0xC7); 626 else 627 EMIT1(0xC7); 628 goto st; 629 case BPF_ST | BPF_MEM | BPF_DW: 630 EMIT2(add_1mod(0x48, dst_reg), 0xC7); 631 632 st: if (is_imm8(insn->off)) 633 EMIT2(add_1reg(0x40, dst_reg), insn->off); 634 else 635 EMIT1_off32(add_1reg(0x80, dst_reg), insn->off); 636 637 EMIT(imm32, bpf_size_to_x86_bytes(BPF_SIZE(insn->code))); 638 break; 639 640 /* STX: *(u8*)(dst_reg + off) = src_reg */ 641 case BPF_STX | BPF_MEM | BPF_B: 642 /* emit 'mov byte ptr [rax + off], al' */ 643 if (is_ereg(dst_reg) || is_ereg(src_reg) || 644 /* have to add extra byte for x86 SIL, DIL regs */ 645 src_reg == BPF_REG_1 || src_reg == BPF_REG_2) 646 EMIT2(add_2mod(0x40, dst_reg, src_reg), 0x88); 647 else 648 EMIT1(0x88); 649 goto stx; 650 case BPF_STX | BPF_MEM | BPF_H: 651 if (is_ereg(dst_reg) || is_ereg(src_reg)) 652 EMIT3(0x66, add_2mod(0x40, dst_reg, src_reg), 0x89); 653 else 654 EMIT2(0x66, 0x89); 655 goto stx; 656 case BPF_STX | BPF_MEM | BPF_W: 657 if (is_ereg(dst_reg) || is_ereg(src_reg)) 658 EMIT2(add_2mod(0x40, dst_reg, src_reg), 0x89); 659 else 660 EMIT1(0x89); 661 goto stx; 662 case BPF_STX | BPF_MEM | BPF_DW: 663 EMIT2(add_2mod(0x48, dst_reg, src_reg), 0x89); 664 stx: if (is_imm8(insn->off)) 665 EMIT2(add_2reg(0x40, dst_reg, src_reg), insn->off); 666 else 667 EMIT1_off32(add_2reg(0x80, dst_reg, src_reg), 668 insn->off); 669 break; 670 671 /* LDX: dst_reg = *(u8*)(src_reg + off) */ 672 case BPF_LDX | BPF_MEM | BPF_B: 673 /* emit 'movzx rax, byte ptr [rax + off]' */ 674 EMIT3(add_2mod(0x48, src_reg, dst_reg), 0x0F, 0xB6); 675 goto ldx; 676 case BPF_LDX | BPF_MEM | BPF_H: 677 /* emit 'movzx rax, word ptr [rax + off]' */ 678 EMIT3(add_2mod(0x48, src_reg, dst_reg), 0x0F, 0xB7); 679 goto ldx; 680 case BPF_LDX | BPF_MEM | BPF_W: 681 /* emit 'mov eax, dword ptr [rax+0x14]' */ 682 if (is_ereg(dst_reg) || is_ereg(src_reg)) 683 EMIT2(add_2mod(0x40, src_reg, dst_reg), 0x8B); 684 else 685 EMIT1(0x8B); 686 goto ldx; 687 case BPF_LDX | BPF_MEM | BPF_DW: 688 /* emit 'mov rax, qword ptr [rax+0x14]' */ 689 EMIT2(add_2mod(0x48, src_reg, dst_reg), 0x8B); 690 ldx: /* if insn->off == 0 we can save one extra byte, but 691 * special case of x86 r13 which always needs an offset 692 * is not worth the hassle 693 */ 694 if (is_imm8(insn->off)) 695 EMIT2(add_2reg(0x40, src_reg, dst_reg), insn->off); 696 else 697 EMIT1_off32(add_2reg(0x80, src_reg, dst_reg), 698 insn->off); 699 break; 700 701 /* STX XADD: lock *(u32*)(dst_reg + off) += src_reg */ 702 case BPF_STX | BPF_XADD | BPF_W: 703 /* emit 'lock add dword ptr [rax + off], eax' */ 704 if (is_ereg(dst_reg) || is_ereg(src_reg)) 705 EMIT3(0xF0, add_2mod(0x40, dst_reg, src_reg), 0x01); 706 else 707 EMIT2(0xF0, 0x01); 708 goto xadd; 709 case BPF_STX | BPF_XADD | BPF_DW: 710 EMIT3(0xF0, add_2mod(0x48, dst_reg, src_reg), 0x01); 711 xadd: if (is_imm8(insn->off)) 712 EMIT2(add_2reg(0x40, dst_reg, src_reg), insn->off); 713 else 714 EMIT1_off32(add_2reg(0x80, dst_reg, src_reg), 715 insn->off); 716 break; 717 718 /* call */ 719 case BPF_JMP | BPF_CALL: 720 func = (u8 *) __bpf_call_base + imm32; 721 jmp_offset = func - (image + addrs[i]); 722 if (seen_ld_abs) { 723 EMIT2(0x41, 0x52); /* push %r10 */ 724 EMIT2(0x41, 0x51); /* push %r9 */ 725 /* need to adjust jmp offset, since 726 * pop %r9, pop %r10 take 4 bytes after call insn 727 */ 728 jmp_offset += 4; 729 } 730 if (!imm32 || !is_simm32(jmp_offset)) { 731 pr_err("unsupported bpf func %d addr %p image %p\n", 732 imm32, func, image); 733 return -EINVAL; 734 } 735 EMIT1_off32(0xE8, jmp_offset); 736 if (seen_ld_abs) { 737 EMIT2(0x41, 0x59); /* pop %r9 */ 738 EMIT2(0x41, 0x5A); /* pop %r10 */ 739 } 740 break; 741 742 /* cond jump */ 743 case BPF_JMP | BPF_JEQ | BPF_X: 744 case BPF_JMP | BPF_JNE | BPF_X: 745 case BPF_JMP | BPF_JGT | BPF_X: 746 case BPF_JMP | BPF_JGE | BPF_X: 747 case BPF_JMP | BPF_JSGT | BPF_X: 748 case BPF_JMP | BPF_JSGE | BPF_X: 749 /* cmp dst_reg, src_reg */ 750 EMIT3(add_2mod(0x48, dst_reg, src_reg), 0x39, 751 add_2reg(0xC0, dst_reg, src_reg)); 752 goto emit_cond_jmp; 753 754 case BPF_JMP | BPF_JSET | BPF_X: 755 /* test dst_reg, src_reg */ 756 EMIT3(add_2mod(0x48, dst_reg, src_reg), 0x85, 757 add_2reg(0xC0, dst_reg, src_reg)); 758 goto emit_cond_jmp; 759 760 case BPF_JMP | BPF_JSET | BPF_K: 761 /* test dst_reg, imm32 */ 762 EMIT1(add_1mod(0x48, dst_reg)); 763 EMIT2_off32(0xF7, add_1reg(0xC0, dst_reg), imm32); 764 goto emit_cond_jmp; 765 766 case BPF_JMP | BPF_JEQ | BPF_K: 767 case BPF_JMP | BPF_JNE | BPF_K: 768 case BPF_JMP | BPF_JGT | BPF_K: 769 case BPF_JMP | BPF_JGE | BPF_K: 770 case BPF_JMP | BPF_JSGT | BPF_K: 771 case BPF_JMP | BPF_JSGE | BPF_K: 772 /* cmp dst_reg, imm8/32 */ 773 EMIT1(add_1mod(0x48, dst_reg)); 774 775 if (is_imm8(imm32)) 776 EMIT3(0x83, add_1reg(0xF8, dst_reg), imm32); 777 else 778 EMIT2_off32(0x81, add_1reg(0xF8, dst_reg), imm32); 779 780 emit_cond_jmp: /* convert BPF opcode to x86 */ 781 switch (BPF_OP(insn->code)) { 782 case BPF_JEQ: 783 jmp_cond = X86_JE; 784 break; 785 case BPF_JSET: 786 case BPF_JNE: 787 jmp_cond = X86_JNE; 788 break; 789 case BPF_JGT: 790 /* GT is unsigned '>', JA in x86 */ 791 jmp_cond = X86_JA; 792 break; 793 case BPF_JGE: 794 /* GE is unsigned '>=', JAE in x86 */ 795 jmp_cond = X86_JAE; 796 break; 797 case BPF_JSGT: 798 /* signed '>', GT in x86 */ 799 jmp_cond = X86_JG; 800 break; 801 case BPF_JSGE: 802 /* signed '>=', GE in x86 */ 803 jmp_cond = X86_JGE; 804 break; 805 default: /* to silence gcc warning */ 806 return -EFAULT; 807 } 808 jmp_offset = addrs[i + insn->off] - addrs[i]; 809 if (is_imm8(jmp_offset)) { 810 EMIT2(jmp_cond, jmp_offset); 811 } else if (is_simm32(jmp_offset)) { 812 EMIT2_off32(0x0F, jmp_cond + 0x10, jmp_offset); 813 } else { 814 pr_err("cond_jmp gen bug %llx\n", jmp_offset); 815 return -EFAULT; 816 } 817 818 break; 819 820 case BPF_JMP | BPF_JA: 821 jmp_offset = addrs[i + insn->off] - addrs[i]; 822 if (!jmp_offset) 823 /* optimize out nop jumps */ 824 break; 825 emit_jmp: 826 if (is_imm8(jmp_offset)) { 827 EMIT2(0xEB, jmp_offset); 828 } else if (is_simm32(jmp_offset)) { 829 EMIT1_off32(0xE9, jmp_offset); 830 } else { 831 pr_err("jmp gen bug %llx\n", jmp_offset); 832 return -EFAULT; 833 } 834 break; 835 836 case BPF_LD | BPF_IND | BPF_W: 837 func = sk_load_word; 838 goto common_load; 839 case BPF_LD | BPF_ABS | BPF_W: 840 func = CHOOSE_LOAD_FUNC(imm32, sk_load_word); 841 common_load: 842 ctx->seen_ld_abs = seen_ld_abs = true; 843 jmp_offset = func - (image + addrs[i]); 844 if (!func || !is_simm32(jmp_offset)) { 845 pr_err("unsupported bpf func %d addr %p image %p\n", 846 imm32, func, image); 847 return -EINVAL; 848 } 849 if (BPF_MODE(insn->code) == BPF_ABS) { 850 /* mov %esi, imm32 */ 851 EMIT1_off32(0xBE, imm32); 852 } else { 853 /* mov %rsi, src_reg */ 854 EMIT_mov(BPF_REG_2, src_reg); 855 if (imm32) { 856 if (is_imm8(imm32)) 857 /* add %esi, imm8 */ 858 EMIT3(0x83, 0xC6, imm32); 859 else 860 /* add %esi, imm32 */ 861 EMIT2_off32(0x81, 0xC6, imm32); 862 } 863 } 864 /* skb pointer is in R6 (%rbx), it will be copied into 865 * %rdi if skb_copy_bits() call is necessary. 866 * sk_load_* helpers also use %r10 and %r9d. 867 * See bpf_jit.S 868 */ 869 EMIT1_off32(0xE8, jmp_offset); /* call */ 870 break; 871 872 case BPF_LD | BPF_IND | BPF_H: 873 func = sk_load_half; 874 goto common_load; 875 case BPF_LD | BPF_ABS | BPF_H: 876 func = CHOOSE_LOAD_FUNC(imm32, sk_load_half); 877 goto common_load; 878 case BPF_LD | BPF_IND | BPF_B: 879 func = sk_load_byte; 880 goto common_load; 881 case BPF_LD | BPF_ABS | BPF_B: 882 func = CHOOSE_LOAD_FUNC(imm32, sk_load_byte); 883 goto common_load; 884 885 case BPF_JMP | BPF_EXIT: 886 if (seen_exit) { 887 jmp_offset = ctx->cleanup_addr - addrs[i]; 888 goto emit_jmp; 889 } 890 seen_exit = true; 891 /* update cleanup_addr */ 892 ctx->cleanup_addr = proglen; 893 /* mov rbx, qword ptr [rbp-X] */ 894 EMIT3_off32(0x48, 0x8B, 0x9D, -stacksize); 895 /* mov r13, qword ptr [rbp-X] */ 896 EMIT3_off32(0x4C, 0x8B, 0xAD, -stacksize + 8); 897 /* mov r14, qword ptr [rbp-X] */ 898 EMIT3_off32(0x4C, 0x8B, 0xB5, -stacksize + 16); 899 /* mov r15, qword ptr [rbp-X] */ 900 EMIT3_off32(0x4C, 0x8B, 0xBD, -stacksize + 24); 901 902 EMIT1(0xC9); /* leave */ 903 EMIT1(0xC3); /* ret */ 904 break; 905 906 default: 907 /* By design x64 JIT should support all BPF instructions 908 * This error will be seen if new instruction was added 909 * to interpreter, but not to JIT 910 * or if there is junk in bpf_prog 911 */ 912 pr_err("bpf_jit: unknown opcode %02x\n", insn->code); 913 return -EINVAL; 914 } 915 916 ilen = prog - temp; 917 if (ilen > BPF_MAX_INSN_SIZE) { 918 pr_err("bpf_jit_compile fatal insn size error\n"); 919 return -EFAULT; 920 } 921 922 if (image) { 923 if (unlikely(proglen + ilen > oldproglen)) { 924 pr_err("bpf_jit_compile fatal error\n"); 925 return -EFAULT; 926 } 927 memcpy(image + proglen, temp, ilen); 928 } 929 proglen += ilen; 930 addrs[i] = proglen; 931 prog = temp; 932 } 933 return proglen; 934 } 935 936 void bpf_jit_compile(struct bpf_prog *prog) 937 { 938 } 939 940 void bpf_int_jit_compile(struct bpf_prog *prog) 941 { 942 struct bpf_binary_header *header = NULL; 943 int proglen, oldproglen = 0; 944 struct jit_context ctx = {}; 945 u8 *image = NULL; 946 int *addrs; 947 int pass; 948 int i; 949 950 if (!bpf_jit_enable) 951 return; 952 953 if (!prog || !prog->len) 954 return; 955 956 addrs = kmalloc(prog->len * sizeof(*addrs), GFP_KERNEL); 957 if (!addrs) 958 return; 959 960 /* Before first pass, make a rough estimation of addrs[] 961 * each bpf instruction is translated to less than 64 bytes 962 */ 963 for (proglen = 0, i = 0; i < prog->len; i++) { 964 proglen += 64; 965 addrs[i] = proglen; 966 } 967 ctx.cleanup_addr = proglen; 968 969 for (pass = 0; pass < 10; pass++) { 970 proglen = do_jit(prog, addrs, image, oldproglen, &ctx); 971 if (proglen <= 0) { 972 image = NULL; 973 if (header) 974 bpf_jit_binary_free(header); 975 goto out; 976 } 977 if (image) { 978 if (proglen != oldproglen) { 979 pr_err("bpf_jit: proglen=%d != oldproglen=%d\n", 980 proglen, oldproglen); 981 goto out; 982 } 983 break; 984 } 985 if (proglen == oldproglen) { 986 header = bpf_jit_binary_alloc(proglen, &image, 987 1, jit_fill_hole); 988 if (!header) 989 goto out; 990 } 991 oldproglen = proglen; 992 } 993 994 if (bpf_jit_enable > 1) 995 bpf_jit_dump(prog->len, proglen, 0, image); 996 997 if (image) { 998 bpf_flush_icache(header, image + proglen); 999 set_memory_ro((unsigned long)header, header->pages); 1000 prog->bpf_func = (void *)image; 1001 prog->jited = true; 1002 } 1003 out: 1004 kfree(addrs); 1005 } 1006 1007 void bpf_jit_free(struct bpf_prog *fp) 1008 { 1009 unsigned long addr = (unsigned long)fp->bpf_func & PAGE_MASK; 1010 struct bpf_binary_header *header = (void *)addr; 1011 1012 if (!fp->jited) 1013 goto free_filter; 1014 1015 set_memory_rw(addr, header->pages); 1016 bpf_jit_binary_free(header); 1017 1018 free_filter: 1019 bpf_prog_unlock_free(fp); 1020 } 1021