1 /* 2 * Just-In-Time compiler for BPF filters on 32bit ARM 3 * 4 * Copyright (c) 2011 Mircea Gherzan <mgherzan@gmail.com> 5 * 6 * This program is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License as published by the 8 * Free Software Foundation; version 2 of the License. 9 */ 10 11 #include <linux/bitops.h> 12 #include <linux/compiler.h> 13 #include <linux/errno.h> 14 #include <linux/filter.h> 15 #include <linux/moduleloader.h> 16 #include <linux/netdevice.h> 17 #include <linux/string.h> 18 #include <linux/slab.h> 19 #include <linux/if_vlan.h> 20 #include <asm/cacheflush.h> 21 #include <asm/hwcap.h> 22 23 #include "bpf_jit_32.h" 24 25 /* 26 * ABI: 27 * 28 * r0 scratch register 29 * r4 BPF register A 30 * r5 BPF register X 31 * r6 pointer to the skb 32 * r7 skb->data 33 * r8 skb_headlen(skb) 34 */ 35 36 #define r_scratch ARM_R0 37 /* r1-r3 are (also) used for the unaligned loads on the non-ARMv7 slowpath */ 38 #define r_off ARM_R1 39 #define r_A ARM_R4 40 #define r_X ARM_R5 41 #define r_skb ARM_R6 42 #define r_skb_data ARM_R7 43 #define r_skb_hl ARM_R8 44 45 #define SCRATCH_SP_OFFSET 0 46 #define SCRATCH_OFF(k) (SCRATCH_SP_OFFSET + 4 * (k)) 47 48 #define SEEN_MEM ((1 << BPF_MEMWORDS) - 1) 49 #define SEEN_MEM_WORD(k) (1 << (k)) 50 #define SEEN_X (1 << BPF_MEMWORDS) 51 #define SEEN_CALL (1 << (BPF_MEMWORDS + 1)) 52 #define SEEN_SKB (1 << (BPF_MEMWORDS + 2)) 53 #define SEEN_DATA (1 << (BPF_MEMWORDS + 3)) 54 55 #define FLAG_NEED_X_RESET (1 << 0) 56 57 struct jit_ctx { 58 const struct sk_filter *skf; 59 unsigned idx; 60 unsigned prologue_bytes; 61 int ret0_fp_idx; 62 u32 seen; 63 u32 flags; 64 u32 *offsets; 65 u32 *target; 66 #if __LINUX_ARM_ARCH__ < 7 67 u16 epilogue_bytes; 68 u16 imm_count; 69 u32 *imms; 70 #endif 71 }; 72 73 int bpf_jit_enable __read_mostly; 74 75 static u64 jit_get_skb_b(struct sk_buff *skb, unsigned offset) 76 { 77 u8 ret; 78 int err; 79 80 err = skb_copy_bits(skb, offset, &ret, 1); 81 82 return (u64)err << 32 | ret; 83 } 84 85 static u64 jit_get_skb_h(struct sk_buff *skb, unsigned offset) 86 { 87 u16 ret; 88 int err; 89 90 err = skb_copy_bits(skb, offset, &ret, 2); 91 92 return (u64)err << 32 | ntohs(ret); 93 } 94 95 static u64 jit_get_skb_w(struct sk_buff *skb, unsigned offset) 96 { 97 u32 ret; 98 int err; 99 100 err = skb_copy_bits(skb, offset, &ret, 4); 101 102 return (u64)err << 32 | ntohl(ret); 103 } 104 105 /* 106 * Wrapper that handles both OABI and EABI and assures Thumb2 interworking 107 * (where the assembly routines like __aeabi_uidiv could cause problems). 108 */ 109 static u32 jit_udiv(u32 dividend, u32 divisor) 110 { 111 return dividend / divisor; 112 } 113 114 static inline void _emit(int cond, u32 inst, struct jit_ctx *ctx) 115 { 116 if (ctx->target != NULL) 117 ctx->target[ctx->idx] = inst | (cond << 28); 118 119 ctx->idx++; 120 } 121 122 /* 123 * Emit an instruction that will be executed unconditionally. 124 */ 125 static inline void emit(u32 inst, struct jit_ctx *ctx) 126 { 127 _emit(ARM_COND_AL, inst, ctx); 128 } 129 130 static u16 saved_regs(struct jit_ctx *ctx) 131 { 132 u16 ret = 0; 133 134 if ((ctx->skf->len > 1) || 135 (ctx->skf->insns[0].code == BPF_S_RET_A)) 136 ret |= 1 << r_A; 137 138 #ifdef CONFIG_FRAME_POINTER 139 ret |= (1 << ARM_FP) | (1 << ARM_IP) | (1 << ARM_LR) | (1 << ARM_PC); 140 #else 141 if (ctx->seen & SEEN_CALL) 142 ret |= 1 << ARM_LR; 143 #endif 144 if (ctx->seen & (SEEN_DATA | SEEN_SKB)) 145 ret |= 1 << r_skb; 146 if (ctx->seen & SEEN_DATA) 147 ret |= (1 << r_skb_data) | (1 << r_skb_hl); 148 if (ctx->seen & SEEN_X) 149 ret |= 1 << r_X; 150 151 return ret; 152 } 153 154 static inline int mem_words_used(struct jit_ctx *ctx) 155 { 156 /* yes, we do waste some stack space IF there are "holes" in the set" */ 157 return fls(ctx->seen & SEEN_MEM); 158 } 159 160 static inline bool is_load_to_a(u16 inst) 161 { 162 switch (inst) { 163 case BPF_S_LD_W_LEN: 164 case BPF_S_LD_W_ABS: 165 case BPF_S_LD_H_ABS: 166 case BPF_S_LD_B_ABS: 167 case BPF_S_ANC_CPU: 168 case BPF_S_ANC_IFINDEX: 169 case BPF_S_ANC_MARK: 170 case BPF_S_ANC_PROTOCOL: 171 case BPF_S_ANC_RXHASH: 172 case BPF_S_ANC_VLAN_TAG: 173 case BPF_S_ANC_VLAN_TAG_PRESENT: 174 case BPF_S_ANC_QUEUE: 175 return true; 176 default: 177 return false; 178 } 179 } 180 181 static void build_prologue(struct jit_ctx *ctx) 182 { 183 u16 reg_set = saved_regs(ctx); 184 u16 first_inst = ctx->skf->insns[0].code; 185 u16 off; 186 187 #ifdef CONFIG_FRAME_POINTER 188 emit(ARM_MOV_R(ARM_IP, ARM_SP), ctx); 189 emit(ARM_PUSH(reg_set), ctx); 190 emit(ARM_SUB_I(ARM_FP, ARM_IP, 4), ctx); 191 #else 192 if (reg_set) 193 emit(ARM_PUSH(reg_set), ctx); 194 #endif 195 196 if (ctx->seen & (SEEN_DATA | SEEN_SKB)) 197 emit(ARM_MOV_R(r_skb, ARM_R0), ctx); 198 199 if (ctx->seen & SEEN_DATA) { 200 off = offsetof(struct sk_buff, data); 201 emit(ARM_LDR_I(r_skb_data, r_skb, off), ctx); 202 /* headlen = len - data_len */ 203 off = offsetof(struct sk_buff, len); 204 emit(ARM_LDR_I(r_skb_hl, r_skb, off), ctx); 205 off = offsetof(struct sk_buff, data_len); 206 emit(ARM_LDR_I(r_scratch, r_skb, off), ctx); 207 emit(ARM_SUB_R(r_skb_hl, r_skb_hl, r_scratch), ctx); 208 } 209 210 if (ctx->flags & FLAG_NEED_X_RESET) 211 emit(ARM_MOV_I(r_X, 0), ctx); 212 213 /* do not leak kernel data to userspace */ 214 if ((first_inst != BPF_S_RET_K) && !(is_load_to_a(first_inst))) 215 emit(ARM_MOV_I(r_A, 0), ctx); 216 217 /* stack space for the BPF_MEM words */ 218 if (ctx->seen & SEEN_MEM) 219 emit(ARM_SUB_I(ARM_SP, ARM_SP, mem_words_used(ctx) * 4), ctx); 220 } 221 222 static void build_epilogue(struct jit_ctx *ctx) 223 { 224 u16 reg_set = saved_regs(ctx); 225 226 if (ctx->seen & SEEN_MEM) 227 emit(ARM_ADD_I(ARM_SP, ARM_SP, mem_words_used(ctx) * 4), ctx); 228 229 reg_set &= ~(1 << ARM_LR); 230 231 #ifdef CONFIG_FRAME_POINTER 232 /* the first instruction of the prologue was: mov ip, sp */ 233 reg_set &= ~(1 << ARM_IP); 234 reg_set |= (1 << ARM_SP); 235 emit(ARM_LDM(ARM_SP, reg_set), ctx); 236 #else 237 if (reg_set) { 238 if (ctx->seen & SEEN_CALL) 239 reg_set |= 1 << ARM_PC; 240 emit(ARM_POP(reg_set), ctx); 241 } 242 243 if (!(ctx->seen & SEEN_CALL)) 244 emit(ARM_BX(ARM_LR), ctx); 245 #endif 246 } 247 248 static int16_t imm8m(u32 x) 249 { 250 u32 rot; 251 252 for (rot = 0; rot < 16; rot++) 253 if ((x & ~ror32(0xff, 2 * rot)) == 0) 254 return rol32(x, 2 * rot) | (rot << 8); 255 256 return -1; 257 } 258 259 #if __LINUX_ARM_ARCH__ < 7 260 261 static u16 imm_offset(u32 k, struct jit_ctx *ctx) 262 { 263 unsigned i = 0, offset; 264 u16 imm; 265 266 /* on the "fake" run we just count them (duplicates included) */ 267 if (ctx->target == NULL) { 268 ctx->imm_count++; 269 return 0; 270 } 271 272 while ((i < ctx->imm_count) && ctx->imms[i]) { 273 if (ctx->imms[i] == k) 274 break; 275 i++; 276 } 277 278 if (ctx->imms[i] == 0) 279 ctx->imms[i] = k; 280 281 /* constants go just after the epilogue */ 282 offset = ctx->offsets[ctx->skf->len]; 283 offset += ctx->prologue_bytes; 284 offset += ctx->epilogue_bytes; 285 offset += i * 4; 286 287 ctx->target[offset / 4] = k; 288 289 /* PC in ARM mode == address of the instruction + 8 */ 290 imm = offset - (8 + ctx->idx * 4); 291 292 return imm; 293 } 294 295 #endif /* __LINUX_ARM_ARCH__ */ 296 297 /* 298 * Move an immediate that's not an imm8m to a core register. 299 */ 300 static inline void emit_mov_i_no8m(int rd, u32 val, struct jit_ctx *ctx) 301 { 302 #if __LINUX_ARM_ARCH__ < 7 303 emit(ARM_LDR_I(rd, ARM_PC, imm_offset(val, ctx)), ctx); 304 #else 305 emit(ARM_MOVW(rd, val & 0xffff), ctx); 306 if (val > 0xffff) 307 emit(ARM_MOVT(rd, val >> 16), ctx); 308 #endif 309 } 310 311 static inline void emit_mov_i(int rd, u32 val, struct jit_ctx *ctx) 312 { 313 int imm12 = imm8m(val); 314 315 if (imm12 >= 0) 316 emit(ARM_MOV_I(rd, imm12), ctx); 317 else 318 emit_mov_i_no8m(rd, val, ctx); 319 } 320 321 #if __LINUX_ARM_ARCH__ < 6 322 323 static void emit_load_be32(u8 cond, u8 r_res, u8 r_addr, struct jit_ctx *ctx) 324 { 325 _emit(cond, ARM_LDRB_I(ARM_R3, r_addr, 1), ctx); 326 _emit(cond, ARM_LDRB_I(ARM_R1, r_addr, 0), ctx); 327 _emit(cond, ARM_LDRB_I(ARM_R2, r_addr, 3), ctx); 328 _emit(cond, ARM_LSL_I(ARM_R3, ARM_R3, 16), ctx); 329 _emit(cond, ARM_LDRB_I(ARM_R0, r_addr, 2), ctx); 330 _emit(cond, ARM_ORR_S(ARM_R3, ARM_R3, ARM_R1, SRTYPE_LSL, 24), ctx); 331 _emit(cond, ARM_ORR_R(ARM_R3, ARM_R3, ARM_R2), ctx); 332 _emit(cond, ARM_ORR_S(r_res, ARM_R3, ARM_R0, SRTYPE_LSL, 8), ctx); 333 } 334 335 static void emit_load_be16(u8 cond, u8 r_res, u8 r_addr, struct jit_ctx *ctx) 336 { 337 _emit(cond, ARM_LDRB_I(ARM_R1, r_addr, 0), ctx); 338 _emit(cond, ARM_LDRB_I(ARM_R2, r_addr, 1), ctx); 339 _emit(cond, ARM_ORR_S(r_res, ARM_R2, ARM_R1, SRTYPE_LSL, 8), ctx); 340 } 341 342 static inline void emit_swap16(u8 r_dst, u8 r_src, struct jit_ctx *ctx) 343 { 344 /* r_dst = (r_src << 8) | (r_src >> 8) */ 345 emit(ARM_LSL_I(ARM_R1, r_src, 8), ctx); 346 emit(ARM_ORR_S(r_dst, ARM_R1, r_src, SRTYPE_LSR, 8), ctx); 347 348 /* 349 * we need to mask out the bits set in r_dst[23:16] due to 350 * the first shift instruction. 351 * 352 * note that 0x8ff is the encoded immediate 0x00ff0000. 353 */ 354 emit(ARM_BIC_I(r_dst, r_dst, 0x8ff), ctx); 355 } 356 357 #else /* ARMv6+ */ 358 359 static void emit_load_be32(u8 cond, u8 r_res, u8 r_addr, struct jit_ctx *ctx) 360 { 361 _emit(cond, ARM_LDR_I(r_res, r_addr, 0), ctx); 362 #ifdef __LITTLE_ENDIAN 363 _emit(cond, ARM_REV(r_res, r_res), ctx); 364 #endif 365 } 366 367 static void emit_load_be16(u8 cond, u8 r_res, u8 r_addr, struct jit_ctx *ctx) 368 { 369 _emit(cond, ARM_LDRH_I(r_res, r_addr, 0), ctx); 370 #ifdef __LITTLE_ENDIAN 371 _emit(cond, ARM_REV16(r_res, r_res), ctx); 372 #endif 373 } 374 375 static inline void emit_swap16(u8 r_dst __maybe_unused, 376 u8 r_src __maybe_unused, 377 struct jit_ctx *ctx __maybe_unused) 378 { 379 #ifdef __LITTLE_ENDIAN 380 emit(ARM_REV16(r_dst, r_src), ctx); 381 #endif 382 } 383 384 #endif /* __LINUX_ARM_ARCH__ < 6 */ 385 386 387 /* Compute the immediate value for a PC-relative branch. */ 388 static inline u32 b_imm(unsigned tgt, struct jit_ctx *ctx) 389 { 390 u32 imm; 391 392 if (ctx->target == NULL) 393 return 0; 394 /* 395 * BPF allows only forward jumps and the offset of the target is 396 * still the one computed during the first pass. 397 */ 398 imm = ctx->offsets[tgt] + ctx->prologue_bytes - (ctx->idx * 4 + 8); 399 400 return imm >> 2; 401 } 402 403 #define OP_IMM3(op, r1, r2, imm_val, ctx) \ 404 do { \ 405 imm12 = imm8m(imm_val); \ 406 if (imm12 < 0) { \ 407 emit_mov_i_no8m(r_scratch, imm_val, ctx); \ 408 emit(op ## _R((r1), (r2), r_scratch), ctx); \ 409 } else { \ 410 emit(op ## _I((r1), (r2), imm12), ctx); \ 411 } \ 412 } while (0) 413 414 static inline void emit_err_ret(u8 cond, struct jit_ctx *ctx) 415 { 416 if (ctx->ret0_fp_idx >= 0) { 417 _emit(cond, ARM_B(b_imm(ctx->ret0_fp_idx, ctx)), ctx); 418 /* NOP to keep the size constant between passes */ 419 emit(ARM_MOV_R(ARM_R0, ARM_R0), ctx); 420 } else { 421 _emit(cond, ARM_MOV_I(ARM_R0, 0), ctx); 422 _emit(cond, ARM_B(b_imm(ctx->skf->len, ctx)), ctx); 423 } 424 } 425 426 static inline void emit_blx_r(u8 tgt_reg, struct jit_ctx *ctx) 427 { 428 #if __LINUX_ARM_ARCH__ < 5 429 emit(ARM_MOV_R(ARM_LR, ARM_PC), ctx); 430 431 if (elf_hwcap & HWCAP_THUMB) 432 emit(ARM_BX(tgt_reg), ctx); 433 else 434 emit(ARM_MOV_R(ARM_PC, tgt_reg), ctx); 435 #else 436 emit(ARM_BLX_R(tgt_reg), ctx); 437 #endif 438 } 439 440 static inline void emit_udiv(u8 rd, u8 rm, u8 rn, struct jit_ctx *ctx) 441 { 442 #if __LINUX_ARM_ARCH__ == 7 443 if (elf_hwcap & HWCAP_IDIVA) { 444 emit(ARM_UDIV(rd, rm, rn), ctx); 445 return; 446 } 447 #endif 448 if (rm != ARM_R0) 449 emit(ARM_MOV_R(ARM_R0, rm), ctx); 450 if (rn != ARM_R1) 451 emit(ARM_MOV_R(ARM_R1, rn), ctx); 452 453 ctx->seen |= SEEN_CALL; 454 emit_mov_i(ARM_R3, (u32)jit_udiv, ctx); 455 emit_blx_r(ARM_R3, ctx); 456 457 if (rd != ARM_R0) 458 emit(ARM_MOV_R(rd, ARM_R0), ctx); 459 } 460 461 static inline void update_on_xread(struct jit_ctx *ctx) 462 { 463 if (!(ctx->seen & SEEN_X)) 464 ctx->flags |= FLAG_NEED_X_RESET; 465 466 ctx->seen |= SEEN_X; 467 } 468 469 static int build_body(struct jit_ctx *ctx) 470 { 471 void *load_func[] = {jit_get_skb_b, jit_get_skb_h, jit_get_skb_w}; 472 const struct sk_filter *prog = ctx->skf; 473 const struct sock_filter *inst; 474 unsigned i, load_order, off, condt; 475 int imm12; 476 u32 k; 477 478 for (i = 0; i < prog->len; i++) { 479 inst = &(prog->insns[i]); 480 /* K as an immediate value operand */ 481 k = inst->k; 482 483 /* compute offsets only in the fake pass */ 484 if (ctx->target == NULL) 485 ctx->offsets[i] = ctx->idx * 4; 486 487 switch (inst->code) { 488 case BPF_S_LD_IMM: 489 emit_mov_i(r_A, k, ctx); 490 break; 491 case BPF_S_LD_W_LEN: 492 ctx->seen |= SEEN_SKB; 493 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4); 494 emit(ARM_LDR_I(r_A, r_skb, 495 offsetof(struct sk_buff, len)), ctx); 496 break; 497 case BPF_S_LD_MEM: 498 /* A = scratch[k] */ 499 ctx->seen |= SEEN_MEM_WORD(k); 500 emit(ARM_LDR_I(r_A, ARM_SP, SCRATCH_OFF(k)), ctx); 501 break; 502 case BPF_S_LD_W_ABS: 503 load_order = 2; 504 goto load; 505 case BPF_S_LD_H_ABS: 506 load_order = 1; 507 goto load; 508 case BPF_S_LD_B_ABS: 509 load_order = 0; 510 load: 511 /* the interpreter will deal with the negative K */ 512 if ((int)k < 0) 513 return -ENOTSUPP; 514 emit_mov_i(r_off, k, ctx); 515 load_common: 516 ctx->seen |= SEEN_DATA | SEEN_CALL; 517 518 if (load_order > 0) { 519 emit(ARM_SUB_I(r_scratch, r_skb_hl, 520 1 << load_order), ctx); 521 emit(ARM_CMP_R(r_scratch, r_off), ctx); 522 condt = ARM_COND_HS; 523 } else { 524 emit(ARM_CMP_R(r_skb_hl, r_off), ctx); 525 condt = ARM_COND_HI; 526 } 527 528 _emit(condt, ARM_ADD_R(r_scratch, r_off, r_skb_data), 529 ctx); 530 531 if (load_order == 0) 532 _emit(condt, ARM_LDRB_I(r_A, r_scratch, 0), 533 ctx); 534 else if (load_order == 1) 535 emit_load_be16(condt, r_A, r_scratch, ctx); 536 else if (load_order == 2) 537 emit_load_be32(condt, r_A, r_scratch, ctx); 538 539 _emit(condt, ARM_B(b_imm(i + 1, ctx)), ctx); 540 541 /* the slowpath */ 542 emit_mov_i(ARM_R3, (u32)load_func[load_order], ctx); 543 emit(ARM_MOV_R(ARM_R0, r_skb), ctx); 544 /* the offset is already in R1 */ 545 emit_blx_r(ARM_R3, ctx); 546 /* check the result of skb_copy_bits */ 547 emit(ARM_CMP_I(ARM_R1, 0), ctx); 548 emit_err_ret(ARM_COND_NE, ctx); 549 emit(ARM_MOV_R(r_A, ARM_R0), ctx); 550 break; 551 case BPF_S_LD_W_IND: 552 load_order = 2; 553 goto load_ind; 554 case BPF_S_LD_H_IND: 555 load_order = 1; 556 goto load_ind; 557 case BPF_S_LD_B_IND: 558 load_order = 0; 559 load_ind: 560 OP_IMM3(ARM_ADD, r_off, r_X, k, ctx); 561 goto load_common; 562 case BPF_S_LDX_IMM: 563 ctx->seen |= SEEN_X; 564 emit_mov_i(r_X, k, ctx); 565 break; 566 case BPF_S_LDX_W_LEN: 567 ctx->seen |= SEEN_X | SEEN_SKB; 568 emit(ARM_LDR_I(r_X, r_skb, 569 offsetof(struct sk_buff, len)), ctx); 570 break; 571 case BPF_S_LDX_MEM: 572 ctx->seen |= SEEN_X | SEEN_MEM_WORD(k); 573 emit(ARM_LDR_I(r_X, ARM_SP, SCRATCH_OFF(k)), ctx); 574 break; 575 case BPF_S_LDX_B_MSH: 576 /* x = ((*(frame + k)) & 0xf) << 2; */ 577 ctx->seen |= SEEN_X | SEEN_DATA | SEEN_CALL; 578 /* the interpreter should deal with the negative K */ 579 if ((int)k < 0) 580 return -1; 581 /* offset in r1: we might have to take the slow path */ 582 emit_mov_i(r_off, k, ctx); 583 emit(ARM_CMP_R(r_skb_hl, r_off), ctx); 584 585 /* load in r0: common with the slowpath */ 586 _emit(ARM_COND_HI, ARM_LDRB_R(ARM_R0, r_skb_data, 587 ARM_R1), ctx); 588 /* 589 * emit_mov_i() might generate one or two instructions, 590 * the same holds for emit_blx_r() 591 */ 592 _emit(ARM_COND_HI, ARM_B(b_imm(i + 1, ctx) - 2), ctx); 593 594 emit(ARM_MOV_R(ARM_R0, r_skb), ctx); 595 /* r_off is r1 */ 596 emit_mov_i(ARM_R3, (u32)jit_get_skb_b, ctx); 597 emit_blx_r(ARM_R3, ctx); 598 /* check the return value of skb_copy_bits */ 599 emit(ARM_CMP_I(ARM_R1, 0), ctx); 600 emit_err_ret(ARM_COND_NE, ctx); 601 602 emit(ARM_AND_I(r_X, ARM_R0, 0x00f), ctx); 603 emit(ARM_LSL_I(r_X, r_X, 2), ctx); 604 break; 605 case BPF_S_ST: 606 ctx->seen |= SEEN_MEM_WORD(k); 607 emit(ARM_STR_I(r_A, ARM_SP, SCRATCH_OFF(k)), ctx); 608 break; 609 case BPF_S_STX: 610 update_on_xread(ctx); 611 ctx->seen |= SEEN_MEM_WORD(k); 612 emit(ARM_STR_I(r_X, ARM_SP, SCRATCH_OFF(k)), ctx); 613 break; 614 case BPF_S_ALU_ADD_K: 615 /* A += K */ 616 OP_IMM3(ARM_ADD, r_A, r_A, k, ctx); 617 break; 618 case BPF_S_ALU_ADD_X: 619 update_on_xread(ctx); 620 emit(ARM_ADD_R(r_A, r_A, r_X), ctx); 621 break; 622 case BPF_S_ALU_SUB_K: 623 /* A -= K */ 624 OP_IMM3(ARM_SUB, r_A, r_A, k, ctx); 625 break; 626 case BPF_S_ALU_SUB_X: 627 update_on_xread(ctx); 628 emit(ARM_SUB_R(r_A, r_A, r_X), ctx); 629 break; 630 case BPF_S_ALU_MUL_K: 631 /* A *= K */ 632 emit_mov_i(r_scratch, k, ctx); 633 emit(ARM_MUL(r_A, r_A, r_scratch), ctx); 634 break; 635 case BPF_S_ALU_MUL_X: 636 update_on_xread(ctx); 637 emit(ARM_MUL(r_A, r_A, r_X), ctx); 638 break; 639 case BPF_S_ALU_DIV_K: 640 /* current k == reciprocal_value(userspace k) */ 641 emit_mov_i(r_scratch, k, ctx); 642 /* A = top 32 bits of the product */ 643 emit(ARM_UMULL(r_scratch, r_A, r_A, r_scratch), ctx); 644 break; 645 case BPF_S_ALU_DIV_X: 646 update_on_xread(ctx); 647 emit(ARM_CMP_I(r_X, 0), ctx); 648 emit_err_ret(ARM_COND_EQ, ctx); 649 emit_udiv(r_A, r_A, r_X, ctx); 650 break; 651 case BPF_S_ALU_OR_K: 652 /* A |= K */ 653 OP_IMM3(ARM_ORR, r_A, r_A, k, ctx); 654 break; 655 case BPF_S_ALU_OR_X: 656 update_on_xread(ctx); 657 emit(ARM_ORR_R(r_A, r_A, r_X), ctx); 658 break; 659 case BPF_S_ALU_XOR_K: 660 /* A ^= K; */ 661 OP_IMM3(ARM_EOR, r_A, r_A, k, ctx); 662 break; 663 case BPF_S_ANC_ALU_XOR_X: 664 case BPF_S_ALU_XOR_X: 665 /* A ^= X */ 666 update_on_xread(ctx); 667 emit(ARM_EOR_R(r_A, r_A, r_X), ctx); 668 break; 669 case BPF_S_ALU_AND_K: 670 /* A &= K */ 671 OP_IMM3(ARM_AND, r_A, r_A, k, ctx); 672 break; 673 case BPF_S_ALU_AND_X: 674 update_on_xread(ctx); 675 emit(ARM_AND_R(r_A, r_A, r_X), ctx); 676 break; 677 case BPF_S_ALU_LSH_K: 678 if (unlikely(k > 31)) 679 return -1; 680 emit(ARM_LSL_I(r_A, r_A, k), ctx); 681 break; 682 case BPF_S_ALU_LSH_X: 683 update_on_xread(ctx); 684 emit(ARM_LSL_R(r_A, r_A, r_X), ctx); 685 break; 686 case BPF_S_ALU_RSH_K: 687 if (unlikely(k > 31)) 688 return -1; 689 emit(ARM_LSR_I(r_A, r_A, k), ctx); 690 break; 691 case BPF_S_ALU_RSH_X: 692 update_on_xread(ctx); 693 emit(ARM_LSR_R(r_A, r_A, r_X), ctx); 694 break; 695 case BPF_S_ALU_NEG: 696 /* A = -A */ 697 emit(ARM_RSB_I(r_A, r_A, 0), ctx); 698 break; 699 case BPF_S_JMP_JA: 700 /* pc += K */ 701 emit(ARM_B(b_imm(i + k + 1, ctx)), ctx); 702 break; 703 case BPF_S_JMP_JEQ_K: 704 /* pc += (A == K) ? pc->jt : pc->jf */ 705 condt = ARM_COND_EQ; 706 goto cmp_imm; 707 case BPF_S_JMP_JGT_K: 708 /* pc += (A > K) ? pc->jt : pc->jf */ 709 condt = ARM_COND_HI; 710 goto cmp_imm; 711 case BPF_S_JMP_JGE_K: 712 /* pc += (A >= K) ? pc->jt : pc->jf */ 713 condt = ARM_COND_HS; 714 cmp_imm: 715 imm12 = imm8m(k); 716 if (imm12 < 0) { 717 emit_mov_i_no8m(r_scratch, k, ctx); 718 emit(ARM_CMP_R(r_A, r_scratch), ctx); 719 } else { 720 emit(ARM_CMP_I(r_A, imm12), ctx); 721 } 722 cond_jump: 723 if (inst->jt) 724 _emit(condt, ARM_B(b_imm(i + inst->jt + 1, 725 ctx)), ctx); 726 if (inst->jf) 727 _emit(condt ^ 1, ARM_B(b_imm(i + inst->jf + 1, 728 ctx)), ctx); 729 break; 730 case BPF_S_JMP_JEQ_X: 731 /* pc += (A == X) ? pc->jt : pc->jf */ 732 condt = ARM_COND_EQ; 733 goto cmp_x; 734 case BPF_S_JMP_JGT_X: 735 /* pc += (A > X) ? pc->jt : pc->jf */ 736 condt = ARM_COND_HI; 737 goto cmp_x; 738 case BPF_S_JMP_JGE_X: 739 /* pc += (A >= X) ? pc->jt : pc->jf */ 740 condt = ARM_COND_CS; 741 cmp_x: 742 update_on_xread(ctx); 743 emit(ARM_CMP_R(r_A, r_X), ctx); 744 goto cond_jump; 745 case BPF_S_JMP_JSET_K: 746 /* pc += (A & K) ? pc->jt : pc->jf */ 747 condt = ARM_COND_NE; 748 /* not set iff all zeroes iff Z==1 iff EQ */ 749 750 imm12 = imm8m(k); 751 if (imm12 < 0) { 752 emit_mov_i_no8m(r_scratch, k, ctx); 753 emit(ARM_TST_R(r_A, r_scratch), ctx); 754 } else { 755 emit(ARM_TST_I(r_A, imm12), ctx); 756 } 757 goto cond_jump; 758 case BPF_S_JMP_JSET_X: 759 /* pc += (A & X) ? pc->jt : pc->jf */ 760 update_on_xread(ctx); 761 condt = ARM_COND_NE; 762 emit(ARM_TST_R(r_A, r_X), ctx); 763 goto cond_jump; 764 case BPF_S_RET_A: 765 emit(ARM_MOV_R(ARM_R0, r_A), ctx); 766 goto b_epilogue; 767 case BPF_S_RET_K: 768 if ((k == 0) && (ctx->ret0_fp_idx < 0)) 769 ctx->ret0_fp_idx = i; 770 emit_mov_i(ARM_R0, k, ctx); 771 b_epilogue: 772 if (i != ctx->skf->len - 1) 773 emit(ARM_B(b_imm(prog->len, ctx)), ctx); 774 break; 775 case BPF_S_MISC_TAX: 776 /* X = A */ 777 ctx->seen |= SEEN_X; 778 emit(ARM_MOV_R(r_X, r_A), ctx); 779 break; 780 case BPF_S_MISC_TXA: 781 /* A = X */ 782 update_on_xread(ctx); 783 emit(ARM_MOV_R(r_A, r_X), ctx); 784 break; 785 case BPF_S_ANC_PROTOCOL: 786 /* A = ntohs(skb->protocol) */ 787 ctx->seen |= SEEN_SKB; 788 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, 789 protocol) != 2); 790 off = offsetof(struct sk_buff, protocol); 791 emit(ARM_LDRH_I(r_scratch, r_skb, off), ctx); 792 emit_swap16(r_A, r_scratch, ctx); 793 break; 794 case BPF_S_ANC_CPU: 795 /* r_scratch = current_thread_info() */ 796 OP_IMM3(ARM_BIC, r_scratch, ARM_SP, THREAD_SIZE - 1, ctx); 797 /* A = current_thread_info()->cpu */ 798 BUILD_BUG_ON(FIELD_SIZEOF(struct thread_info, cpu) != 4); 799 off = offsetof(struct thread_info, cpu); 800 emit(ARM_LDR_I(r_A, r_scratch, off), ctx); 801 break; 802 case BPF_S_ANC_IFINDEX: 803 /* A = skb->dev->ifindex */ 804 ctx->seen |= SEEN_SKB; 805 off = offsetof(struct sk_buff, dev); 806 emit(ARM_LDR_I(r_scratch, r_skb, off), ctx); 807 808 emit(ARM_CMP_I(r_scratch, 0), ctx); 809 emit_err_ret(ARM_COND_EQ, ctx); 810 811 BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, 812 ifindex) != 4); 813 off = offsetof(struct net_device, ifindex); 814 emit(ARM_LDR_I(r_A, r_scratch, off), ctx); 815 break; 816 case BPF_S_ANC_MARK: 817 ctx->seen |= SEEN_SKB; 818 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4); 819 off = offsetof(struct sk_buff, mark); 820 emit(ARM_LDR_I(r_A, r_skb, off), ctx); 821 break; 822 case BPF_S_ANC_RXHASH: 823 ctx->seen |= SEEN_SKB; 824 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, rxhash) != 4); 825 off = offsetof(struct sk_buff, rxhash); 826 emit(ARM_LDR_I(r_A, r_skb, off), ctx); 827 break; 828 case BPF_S_ANC_VLAN_TAG: 829 case BPF_S_ANC_VLAN_TAG_PRESENT: 830 ctx->seen |= SEEN_SKB; 831 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, vlan_tci) != 2); 832 off = offsetof(struct sk_buff, vlan_tci); 833 emit(ARM_LDRH_I(r_A, r_skb, off), ctx); 834 if (inst->code == BPF_S_ANC_VLAN_TAG) 835 OP_IMM3(ARM_AND, r_A, r_A, VLAN_VID_MASK, ctx); 836 else 837 OP_IMM3(ARM_AND, r_A, r_A, VLAN_TAG_PRESENT, ctx); 838 break; 839 case BPF_S_ANC_QUEUE: 840 ctx->seen |= SEEN_SKB; 841 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, 842 queue_mapping) != 2); 843 BUILD_BUG_ON(offsetof(struct sk_buff, 844 queue_mapping) > 0xff); 845 off = offsetof(struct sk_buff, queue_mapping); 846 emit(ARM_LDRH_I(r_A, r_skb, off), ctx); 847 break; 848 default: 849 return -1; 850 } 851 } 852 853 /* compute offsets only during the first pass */ 854 if (ctx->target == NULL) 855 ctx->offsets[i] = ctx->idx * 4; 856 857 return 0; 858 } 859 860 861 void bpf_jit_compile(struct sk_filter *fp) 862 { 863 struct jit_ctx ctx; 864 unsigned tmp_idx; 865 unsigned alloc_size; 866 867 if (!bpf_jit_enable) 868 return; 869 870 memset(&ctx, 0, sizeof(ctx)); 871 ctx.skf = fp; 872 ctx.ret0_fp_idx = -1; 873 874 ctx.offsets = kzalloc(4 * (ctx.skf->len + 1), GFP_KERNEL); 875 if (ctx.offsets == NULL) 876 return; 877 878 /* fake pass to fill in the ctx->seen */ 879 if (unlikely(build_body(&ctx))) 880 goto out; 881 882 tmp_idx = ctx.idx; 883 build_prologue(&ctx); 884 ctx.prologue_bytes = (ctx.idx - tmp_idx) * 4; 885 886 #if __LINUX_ARM_ARCH__ < 7 887 tmp_idx = ctx.idx; 888 build_epilogue(&ctx); 889 ctx.epilogue_bytes = (ctx.idx - tmp_idx) * 4; 890 891 ctx.idx += ctx.imm_count; 892 if (ctx.imm_count) { 893 ctx.imms = kzalloc(4 * ctx.imm_count, GFP_KERNEL); 894 if (ctx.imms == NULL) 895 goto out; 896 } 897 #else 898 /* there's nothing after the epilogue on ARMv7 */ 899 build_epilogue(&ctx); 900 #endif 901 902 alloc_size = 4 * ctx.idx; 903 ctx.target = module_alloc(alloc_size); 904 if (unlikely(ctx.target == NULL)) 905 goto out; 906 907 ctx.idx = 0; 908 build_prologue(&ctx); 909 build_body(&ctx); 910 build_epilogue(&ctx); 911 912 flush_icache_range((u32)ctx.target, (u32)(ctx.target + ctx.idx)); 913 914 #if __LINUX_ARM_ARCH__ < 7 915 if (ctx.imm_count) 916 kfree(ctx.imms); 917 #endif 918 919 if (bpf_jit_enable > 1) 920 /* there are 2 passes here */ 921 bpf_jit_dump(fp->len, alloc_size, 2, ctx.target); 922 923 fp->bpf_func = (void *)ctx.target; 924 out: 925 kfree(ctx.offsets); 926 return; 927 } 928 929 void bpf_jit_free(struct sk_filter *fp) 930 { 931 if (fp->bpf_func != sk_run_filter) 932 module_free(NULL, fp->bpf_func); 933 kfree(fp); 934 } 935