1 /* 2 * BPF JIT compiler for ARM64 3 * 4 * Copyright (C) 2014-2016 Zi Shen Lim <zlim.lnx@gmail.com> 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 * 15 * You should have received a copy of the GNU General Public License 16 * along with this program. If not, see <http://www.gnu.org/licenses/>. 17 */ 18 19 #define pr_fmt(fmt) "bpf_jit: " fmt 20 21 #include <linux/bpf.h> 22 #include <linux/filter.h> 23 #include <linux/printk.h> 24 #include <linux/skbuff.h> 25 #include <linux/slab.h> 26 27 #include <asm/byteorder.h> 28 #include <asm/cacheflush.h> 29 #include <asm/debug-monitors.h> 30 #include <asm/set_memory.h> 31 32 #include "bpf_jit.h" 33 34 int bpf_jit_enable __read_mostly; 35 36 #define TMP_REG_1 (MAX_BPF_JIT_REG + 0) 37 #define TMP_REG_2 (MAX_BPF_JIT_REG + 1) 38 #define TCALL_CNT (MAX_BPF_JIT_REG + 2) 39 #define TMP_REG_3 (MAX_BPF_JIT_REG + 3) 40 41 /* Map BPF registers to A64 registers */ 42 static const int bpf2a64[] = { 43 /* return value from in-kernel function, and exit value from eBPF */ 44 [BPF_REG_0] = A64_R(7), 45 /* arguments from eBPF program to in-kernel function */ 46 [BPF_REG_1] = A64_R(0), 47 [BPF_REG_2] = A64_R(1), 48 [BPF_REG_3] = A64_R(2), 49 [BPF_REG_4] = A64_R(3), 50 [BPF_REG_5] = A64_R(4), 51 /* callee saved registers that in-kernel function will preserve */ 52 [BPF_REG_6] = A64_R(19), 53 [BPF_REG_7] = A64_R(20), 54 [BPF_REG_8] = A64_R(21), 55 [BPF_REG_9] = A64_R(22), 56 /* read-only frame pointer to access stack */ 57 [BPF_REG_FP] = A64_R(25), 58 /* temporary registers for internal BPF JIT */ 59 [TMP_REG_1] = A64_R(10), 60 [TMP_REG_2] = A64_R(11), 61 [TMP_REG_3] = A64_R(12), 62 /* tail_call_cnt */ 63 [TCALL_CNT] = A64_R(26), 64 /* temporary register for blinding constants */ 65 [BPF_REG_AX] = A64_R(9), 66 }; 67 68 struct jit_ctx { 69 const struct bpf_prog *prog; 70 int idx; 71 int epilogue_offset; 72 int *offset; 73 __le32 *image; 74 u32 stack_size; 75 }; 76 77 static inline void emit(const u32 insn, struct jit_ctx *ctx) 78 { 79 if (ctx->image != NULL) 80 ctx->image[ctx->idx] = cpu_to_le32(insn); 81 82 ctx->idx++; 83 } 84 85 static inline void emit_a64_mov_i64(const int reg, const u64 val, 86 struct jit_ctx *ctx) 87 { 88 u64 tmp = val; 89 int shift = 0; 90 91 emit(A64_MOVZ(1, reg, tmp & 0xffff, shift), ctx); 92 tmp >>= 16; 93 shift += 16; 94 while (tmp) { 95 if (tmp & 0xffff) 96 emit(A64_MOVK(1, reg, tmp & 0xffff, shift), ctx); 97 tmp >>= 16; 98 shift += 16; 99 } 100 } 101 102 static inline void emit_a64_mov_i(const int is64, const int reg, 103 const s32 val, struct jit_ctx *ctx) 104 { 105 u16 hi = val >> 16; 106 u16 lo = val & 0xffff; 107 108 if (hi & 0x8000) { 109 if (hi == 0xffff) { 110 emit(A64_MOVN(is64, reg, (u16)~lo, 0), ctx); 111 } else { 112 emit(A64_MOVN(is64, reg, (u16)~hi, 16), ctx); 113 emit(A64_MOVK(is64, reg, lo, 0), ctx); 114 } 115 } else { 116 emit(A64_MOVZ(is64, reg, lo, 0), ctx); 117 if (hi) 118 emit(A64_MOVK(is64, reg, hi, 16), ctx); 119 } 120 } 121 122 static inline int bpf2a64_offset(int bpf_to, int bpf_from, 123 const struct jit_ctx *ctx) 124 { 125 int to = ctx->offset[bpf_to]; 126 /* -1 to account for the Branch instruction */ 127 int from = ctx->offset[bpf_from] - 1; 128 129 return to - from; 130 } 131 132 static void jit_fill_hole(void *area, unsigned int size) 133 { 134 __le32 *ptr; 135 /* We are guaranteed to have aligned memory. */ 136 for (ptr = area; size >= sizeof(u32); size -= sizeof(u32)) 137 *ptr++ = cpu_to_le32(AARCH64_BREAK_FAULT); 138 } 139 140 static inline int epilogue_offset(const struct jit_ctx *ctx) 141 { 142 int to = ctx->epilogue_offset; 143 int from = ctx->idx; 144 145 return to - from; 146 } 147 148 /* Stack must be multiples of 16B */ 149 #define STACK_ALIGN(sz) (((sz) + 15) & ~15) 150 151 #define PROLOGUE_OFFSET 8 152 153 static int build_prologue(struct jit_ctx *ctx) 154 { 155 const struct bpf_prog *prog = ctx->prog; 156 const u8 r6 = bpf2a64[BPF_REG_6]; 157 const u8 r7 = bpf2a64[BPF_REG_7]; 158 const u8 r8 = bpf2a64[BPF_REG_8]; 159 const u8 r9 = bpf2a64[BPF_REG_9]; 160 const u8 fp = bpf2a64[BPF_REG_FP]; 161 const u8 tcc = bpf2a64[TCALL_CNT]; 162 const int idx0 = ctx->idx; 163 int cur_offset; 164 165 /* 166 * BPF prog stack layout 167 * 168 * high 169 * original A64_SP => 0:+-----+ BPF prologue 170 * |FP/LR| 171 * current A64_FP => -16:+-----+ 172 * | ... | callee saved registers 173 * BPF fp register => -64:+-----+ <= (BPF_FP) 174 * | | 175 * | ... | BPF prog stack 176 * | | 177 * +-----+ <= (BPF_FP - prog->aux->stack_depth) 178 * |RSVD | JIT scratchpad 179 * current A64_SP => +-----+ <= (BPF_FP - ctx->stack_size) 180 * | | 181 * | ... | Function call stack 182 * | | 183 * +-----+ 184 * low 185 * 186 */ 187 188 /* Save FP and LR registers to stay align with ARM64 AAPCS */ 189 emit(A64_PUSH(A64_FP, A64_LR, A64_SP), ctx); 190 emit(A64_MOV(1, A64_FP, A64_SP), ctx); 191 192 /* Save callee-saved registers */ 193 emit(A64_PUSH(r6, r7, A64_SP), ctx); 194 emit(A64_PUSH(r8, r9, A64_SP), ctx); 195 emit(A64_PUSH(fp, tcc, A64_SP), ctx); 196 197 /* Set up BPF prog stack base register */ 198 emit(A64_MOV(1, fp, A64_SP), ctx); 199 200 /* Initialize tail_call_cnt */ 201 emit(A64_MOVZ(1, tcc, 0, 0), ctx); 202 203 /* 4 byte extra for skb_copy_bits buffer */ 204 ctx->stack_size = prog->aux->stack_depth + 4; 205 ctx->stack_size = STACK_ALIGN(ctx->stack_size); 206 207 /* Set up function call stack */ 208 emit(A64_SUB_I(1, A64_SP, A64_SP, ctx->stack_size), ctx); 209 210 cur_offset = ctx->idx - idx0; 211 if (cur_offset != PROLOGUE_OFFSET) { 212 pr_err_once("PROLOGUE_OFFSET = %d, expected %d!\n", 213 cur_offset, PROLOGUE_OFFSET); 214 return -1; 215 } 216 return 0; 217 } 218 219 static int out_offset = -1; /* initialized on the first pass of build_body() */ 220 static int emit_bpf_tail_call(struct jit_ctx *ctx) 221 { 222 /* bpf_tail_call(void *prog_ctx, struct bpf_array *array, u64 index) */ 223 const u8 r2 = bpf2a64[BPF_REG_2]; 224 const u8 r3 = bpf2a64[BPF_REG_3]; 225 226 const u8 tmp = bpf2a64[TMP_REG_1]; 227 const u8 prg = bpf2a64[TMP_REG_2]; 228 const u8 tcc = bpf2a64[TCALL_CNT]; 229 const int idx0 = ctx->idx; 230 #define cur_offset (ctx->idx - idx0) 231 #define jmp_offset (out_offset - (cur_offset)) 232 size_t off; 233 234 /* if (index >= array->map.max_entries) 235 * goto out; 236 */ 237 off = offsetof(struct bpf_array, map.max_entries); 238 emit_a64_mov_i64(tmp, off, ctx); 239 emit(A64_LDR32(tmp, r2, tmp), ctx); 240 emit(A64_CMP(0, r3, tmp), ctx); 241 emit(A64_B_(A64_COND_GE, jmp_offset), ctx); 242 243 /* if (tail_call_cnt > MAX_TAIL_CALL_CNT) 244 * goto out; 245 * tail_call_cnt++; 246 */ 247 emit_a64_mov_i64(tmp, MAX_TAIL_CALL_CNT, ctx); 248 emit(A64_CMP(1, tcc, tmp), ctx); 249 emit(A64_B_(A64_COND_GT, jmp_offset), ctx); 250 emit(A64_ADD_I(1, tcc, tcc, 1), ctx); 251 252 /* prog = array->ptrs[index]; 253 * if (prog == NULL) 254 * goto out; 255 */ 256 off = offsetof(struct bpf_array, ptrs); 257 emit_a64_mov_i64(tmp, off, ctx); 258 emit(A64_ADD(1, tmp, r2, tmp), ctx); 259 emit(A64_LSL(1, prg, r3, 3), ctx); 260 emit(A64_LDR64(prg, tmp, prg), ctx); 261 emit(A64_CBZ(1, prg, jmp_offset), ctx); 262 263 /* goto *(prog->bpf_func + prologue_size); */ 264 off = offsetof(struct bpf_prog, bpf_func); 265 emit_a64_mov_i64(tmp, off, ctx); 266 emit(A64_LDR64(tmp, prg, tmp), ctx); 267 emit(A64_ADD_I(1, tmp, tmp, sizeof(u32) * PROLOGUE_OFFSET), ctx); 268 emit(A64_BR(tmp), ctx); 269 270 /* out: */ 271 if (out_offset == -1) 272 out_offset = cur_offset; 273 if (cur_offset != out_offset) { 274 pr_err_once("tail_call out_offset = %d, expected %d!\n", 275 cur_offset, out_offset); 276 return -1; 277 } 278 return 0; 279 #undef cur_offset 280 #undef jmp_offset 281 } 282 283 static void build_epilogue(struct jit_ctx *ctx) 284 { 285 const u8 r0 = bpf2a64[BPF_REG_0]; 286 const u8 r6 = bpf2a64[BPF_REG_6]; 287 const u8 r7 = bpf2a64[BPF_REG_7]; 288 const u8 r8 = bpf2a64[BPF_REG_8]; 289 const u8 r9 = bpf2a64[BPF_REG_9]; 290 const u8 fp = bpf2a64[BPF_REG_FP]; 291 292 /* We're done with BPF stack */ 293 emit(A64_ADD_I(1, A64_SP, A64_SP, ctx->stack_size), ctx); 294 295 /* Restore fs (x25) and x26 */ 296 emit(A64_POP(fp, A64_R(26), A64_SP), ctx); 297 298 /* Restore callee-saved register */ 299 emit(A64_POP(r8, r9, A64_SP), ctx); 300 emit(A64_POP(r6, r7, A64_SP), ctx); 301 302 /* Restore FP/LR registers */ 303 emit(A64_POP(A64_FP, A64_LR, A64_SP), ctx); 304 305 /* Set return value */ 306 emit(A64_MOV(1, A64_R(0), r0), ctx); 307 308 emit(A64_RET(A64_LR), ctx); 309 } 310 311 /* JITs an eBPF instruction. 312 * Returns: 313 * 0 - successfully JITed an 8-byte eBPF instruction. 314 * >0 - successfully JITed a 16-byte eBPF instruction. 315 * <0 - failed to JIT. 316 */ 317 static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx) 318 { 319 const u8 code = insn->code; 320 const u8 dst = bpf2a64[insn->dst_reg]; 321 const u8 src = bpf2a64[insn->src_reg]; 322 const u8 tmp = bpf2a64[TMP_REG_1]; 323 const u8 tmp2 = bpf2a64[TMP_REG_2]; 324 const u8 tmp3 = bpf2a64[TMP_REG_3]; 325 const s16 off = insn->off; 326 const s32 imm = insn->imm; 327 const int i = insn - ctx->prog->insnsi; 328 const bool is64 = BPF_CLASS(code) == BPF_ALU64; 329 const bool isdw = BPF_SIZE(code) == BPF_DW; 330 u8 jmp_cond; 331 s32 jmp_offset; 332 333 #define check_imm(bits, imm) do { \ 334 if ((((imm) > 0) && ((imm) >> (bits))) || \ 335 (((imm) < 0) && (~(imm) >> (bits)))) { \ 336 pr_info("[%2d] imm=%d(0x%x) out of range\n", \ 337 i, imm, imm); \ 338 return -EINVAL; \ 339 } \ 340 } while (0) 341 #define check_imm19(imm) check_imm(19, imm) 342 #define check_imm26(imm) check_imm(26, imm) 343 344 switch (code) { 345 /* dst = src */ 346 case BPF_ALU | BPF_MOV | BPF_X: 347 case BPF_ALU64 | BPF_MOV | BPF_X: 348 emit(A64_MOV(is64, dst, src), ctx); 349 break; 350 /* dst = dst OP src */ 351 case BPF_ALU | BPF_ADD | BPF_X: 352 case BPF_ALU64 | BPF_ADD | BPF_X: 353 emit(A64_ADD(is64, dst, dst, src), ctx); 354 break; 355 case BPF_ALU | BPF_SUB | BPF_X: 356 case BPF_ALU64 | BPF_SUB | BPF_X: 357 emit(A64_SUB(is64, dst, dst, src), ctx); 358 break; 359 case BPF_ALU | BPF_AND | BPF_X: 360 case BPF_ALU64 | BPF_AND | BPF_X: 361 emit(A64_AND(is64, dst, dst, src), ctx); 362 break; 363 case BPF_ALU | BPF_OR | BPF_X: 364 case BPF_ALU64 | BPF_OR | BPF_X: 365 emit(A64_ORR(is64, dst, dst, src), ctx); 366 break; 367 case BPF_ALU | BPF_XOR | BPF_X: 368 case BPF_ALU64 | BPF_XOR | BPF_X: 369 emit(A64_EOR(is64, dst, dst, src), ctx); 370 break; 371 case BPF_ALU | BPF_MUL | BPF_X: 372 case BPF_ALU64 | BPF_MUL | BPF_X: 373 emit(A64_MUL(is64, dst, dst, src), ctx); 374 break; 375 case BPF_ALU | BPF_DIV | BPF_X: 376 case BPF_ALU64 | BPF_DIV | BPF_X: 377 case BPF_ALU | BPF_MOD | BPF_X: 378 case BPF_ALU64 | BPF_MOD | BPF_X: 379 { 380 const u8 r0 = bpf2a64[BPF_REG_0]; 381 382 /* if (src == 0) return 0 */ 383 jmp_offset = 3; /* skip ahead to else path */ 384 check_imm19(jmp_offset); 385 emit(A64_CBNZ(is64, src, jmp_offset), ctx); 386 emit(A64_MOVZ(1, r0, 0, 0), ctx); 387 jmp_offset = epilogue_offset(ctx); 388 check_imm26(jmp_offset); 389 emit(A64_B(jmp_offset), ctx); 390 /* else */ 391 switch (BPF_OP(code)) { 392 case BPF_DIV: 393 emit(A64_UDIV(is64, dst, dst, src), ctx); 394 break; 395 case BPF_MOD: 396 emit(A64_UDIV(is64, tmp, dst, src), ctx); 397 emit(A64_MUL(is64, tmp, tmp, src), ctx); 398 emit(A64_SUB(is64, dst, dst, tmp), ctx); 399 break; 400 } 401 break; 402 } 403 case BPF_ALU | BPF_LSH | BPF_X: 404 case BPF_ALU64 | BPF_LSH | BPF_X: 405 emit(A64_LSLV(is64, dst, dst, src), ctx); 406 break; 407 case BPF_ALU | BPF_RSH | BPF_X: 408 case BPF_ALU64 | BPF_RSH | BPF_X: 409 emit(A64_LSRV(is64, dst, dst, src), ctx); 410 break; 411 case BPF_ALU | BPF_ARSH | BPF_X: 412 case BPF_ALU64 | BPF_ARSH | BPF_X: 413 emit(A64_ASRV(is64, dst, dst, src), ctx); 414 break; 415 /* dst = -dst */ 416 case BPF_ALU | BPF_NEG: 417 case BPF_ALU64 | BPF_NEG: 418 emit(A64_NEG(is64, dst, dst), ctx); 419 break; 420 /* dst = BSWAP##imm(dst) */ 421 case BPF_ALU | BPF_END | BPF_FROM_LE: 422 case BPF_ALU | BPF_END | BPF_FROM_BE: 423 #ifdef CONFIG_CPU_BIG_ENDIAN 424 if (BPF_SRC(code) == BPF_FROM_BE) 425 goto emit_bswap_uxt; 426 #else /* !CONFIG_CPU_BIG_ENDIAN */ 427 if (BPF_SRC(code) == BPF_FROM_LE) 428 goto emit_bswap_uxt; 429 #endif 430 switch (imm) { 431 case 16: 432 emit(A64_REV16(is64, dst, dst), ctx); 433 /* zero-extend 16 bits into 64 bits */ 434 emit(A64_UXTH(is64, dst, dst), ctx); 435 break; 436 case 32: 437 emit(A64_REV32(is64, dst, dst), ctx); 438 /* upper 32 bits already cleared */ 439 break; 440 case 64: 441 emit(A64_REV64(dst, dst), ctx); 442 break; 443 } 444 break; 445 emit_bswap_uxt: 446 switch (imm) { 447 case 16: 448 /* zero-extend 16 bits into 64 bits */ 449 emit(A64_UXTH(is64, dst, dst), ctx); 450 break; 451 case 32: 452 /* zero-extend 32 bits into 64 bits */ 453 emit(A64_UXTW(is64, dst, dst), ctx); 454 break; 455 case 64: 456 /* nop */ 457 break; 458 } 459 break; 460 /* dst = imm */ 461 case BPF_ALU | BPF_MOV | BPF_K: 462 case BPF_ALU64 | BPF_MOV | BPF_K: 463 emit_a64_mov_i(is64, dst, imm, ctx); 464 break; 465 /* dst = dst OP imm */ 466 case BPF_ALU | BPF_ADD | BPF_K: 467 case BPF_ALU64 | BPF_ADD | BPF_K: 468 emit_a64_mov_i(is64, tmp, imm, ctx); 469 emit(A64_ADD(is64, dst, dst, tmp), ctx); 470 break; 471 case BPF_ALU | BPF_SUB | BPF_K: 472 case BPF_ALU64 | BPF_SUB | BPF_K: 473 emit_a64_mov_i(is64, tmp, imm, ctx); 474 emit(A64_SUB(is64, dst, dst, tmp), ctx); 475 break; 476 case BPF_ALU | BPF_AND | BPF_K: 477 case BPF_ALU64 | BPF_AND | BPF_K: 478 emit_a64_mov_i(is64, tmp, imm, ctx); 479 emit(A64_AND(is64, dst, dst, tmp), ctx); 480 break; 481 case BPF_ALU | BPF_OR | BPF_K: 482 case BPF_ALU64 | BPF_OR | BPF_K: 483 emit_a64_mov_i(is64, tmp, imm, ctx); 484 emit(A64_ORR(is64, dst, dst, tmp), ctx); 485 break; 486 case BPF_ALU | BPF_XOR | BPF_K: 487 case BPF_ALU64 | BPF_XOR | BPF_K: 488 emit_a64_mov_i(is64, tmp, imm, ctx); 489 emit(A64_EOR(is64, dst, dst, tmp), ctx); 490 break; 491 case BPF_ALU | BPF_MUL | BPF_K: 492 case BPF_ALU64 | BPF_MUL | BPF_K: 493 emit_a64_mov_i(is64, tmp, imm, ctx); 494 emit(A64_MUL(is64, dst, dst, tmp), ctx); 495 break; 496 case BPF_ALU | BPF_DIV | BPF_K: 497 case BPF_ALU64 | BPF_DIV | BPF_K: 498 emit_a64_mov_i(is64, tmp, imm, ctx); 499 emit(A64_UDIV(is64, dst, dst, tmp), ctx); 500 break; 501 case BPF_ALU | BPF_MOD | BPF_K: 502 case BPF_ALU64 | BPF_MOD | BPF_K: 503 emit_a64_mov_i(is64, tmp2, imm, ctx); 504 emit(A64_UDIV(is64, tmp, dst, tmp2), ctx); 505 emit(A64_MUL(is64, tmp, tmp, tmp2), ctx); 506 emit(A64_SUB(is64, dst, dst, tmp), ctx); 507 break; 508 case BPF_ALU | BPF_LSH | BPF_K: 509 case BPF_ALU64 | BPF_LSH | BPF_K: 510 emit(A64_LSL(is64, dst, dst, imm), ctx); 511 break; 512 case BPF_ALU | BPF_RSH | BPF_K: 513 case BPF_ALU64 | BPF_RSH | BPF_K: 514 emit(A64_LSR(is64, dst, dst, imm), ctx); 515 break; 516 case BPF_ALU | BPF_ARSH | BPF_K: 517 case BPF_ALU64 | BPF_ARSH | BPF_K: 518 emit(A64_ASR(is64, dst, dst, imm), ctx); 519 break; 520 521 /* JUMP off */ 522 case BPF_JMP | BPF_JA: 523 jmp_offset = bpf2a64_offset(i + off, i, ctx); 524 check_imm26(jmp_offset); 525 emit(A64_B(jmp_offset), ctx); 526 break; 527 /* IF (dst COND src) JUMP off */ 528 case BPF_JMP | BPF_JEQ | BPF_X: 529 case BPF_JMP | BPF_JGT | BPF_X: 530 case BPF_JMP | BPF_JGE | BPF_X: 531 case BPF_JMP | BPF_JNE | BPF_X: 532 case BPF_JMP | BPF_JSGT | BPF_X: 533 case BPF_JMP | BPF_JSGE | BPF_X: 534 emit(A64_CMP(1, dst, src), ctx); 535 emit_cond_jmp: 536 jmp_offset = bpf2a64_offset(i + off, i, ctx); 537 check_imm19(jmp_offset); 538 switch (BPF_OP(code)) { 539 case BPF_JEQ: 540 jmp_cond = A64_COND_EQ; 541 break; 542 case BPF_JGT: 543 jmp_cond = A64_COND_HI; 544 break; 545 case BPF_JGE: 546 jmp_cond = A64_COND_CS; 547 break; 548 case BPF_JSET: 549 case BPF_JNE: 550 jmp_cond = A64_COND_NE; 551 break; 552 case BPF_JSGT: 553 jmp_cond = A64_COND_GT; 554 break; 555 case BPF_JSGE: 556 jmp_cond = A64_COND_GE; 557 break; 558 default: 559 return -EFAULT; 560 } 561 emit(A64_B_(jmp_cond, jmp_offset), ctx); 562 break; 563 case BPF_JMP | BPF_JSET | BPF_X: 564 emit(A64_TST(1, dst, src), ctx); 565 goto emit_cond_jmp; 566 /* IF (dst COND imm) JUMP off */ 567 case BPF_JMP | BPF_JEQ | BPF_K: 568 case BPF_JMP | BPF_JGT | BPF_K: 569 case BPF_JMP | BPF_JGE | BPF_K: 570 case BPF_JMP | BPF_JNE | BPF_K: 571 case BPF_JMP | BPF_JSGT | BPF_K: 572 case BPF_JMP | BPF_JSGE | BPF_K: 573 emit_a64_mov_i(1, tmp, imm, ctx); 574 emit(A64_CMP(1, dst, tmp), ctx); 575 goto emit_cond_jmp; 576 case BPF_JMP | BPF_JSET | BPF_K: 577 emit_a64_mov_i(1, tmp, imm, ctx); 578 emit(A64_TST(1, dst, tmp), ctx); 579 goto emit_cond_jmp; 580 /* function call */ 581 case BPF_JMP | BPF_CALL: 582 { 583 const u8 r0 = bpf2a64[BPF_REG_0]; 584 const u64 func = (u64)__bpf_call_base + imm; 585 586 emit_a64_mov_i64(tmp, func, ctx); 587 emit(A64_BLR(tmp), ctx); 588 emit(A64_MOV(1, r0, A64_R(0)), ctx); 589 break; 590 } 591 /* tail call */ 592 case BPF_JMP | BPF_TAIL_CALL: 593 if (emit_bpf_tail_call(ctx)) 594 return -EFAULT; 595 break; 596 /* function return */ 597 case BPF_JMP | BPF_EXIT: 598 /* Optimization: when last instruction is EXIT, 599 simply fallthrough to epilogue. */ 600 if (i == ctx->prog->len - 1) 601 break; 602 jmp_offset = epilogue_offset(ctx); 603 check_imm26(jmp_offset); 604 emit(A64_B(jmp_offset), ctx); 605 break; 606 607 /* dst = imm64 */ 608 case BPF_LD | BPF_IMM | BPF_DW: 609 { 610 const struct bpf_insn insn1 = insn[1]; 611 u64 imm64; 612 613 imm64 = (u64)insn1.imm << 32 | (u32)imm; 614 emit_a64_mov_i64(dst, imm64, ctx); 615 616 return 1; 617 } 618 619 /* LDX: dst = *(size *)(src + off) */ 620 case BPF_LDX | BPF_MEM | BPF_W: 621 case BPF_LDX | BPF_MEM | BPF_H: 622 case BPF_LDX | BPF_MEM | BPF_B: 623 case BPF_LDX | BPF_MEM | BPF_DW: 624 emit_a64_mov_i(1, tmp, off, ctx); 625 switch (BPF_SIZE(code)) { 626 case BPF_W: 627 emit(A64_LDR32(dst, src, tmp), ctx); 628 break; 629 case BPF_H: 630 emit(A64_LDRH(dst, src, tmp), ctx); 631 break; 632 case BPF_B: 633 emit(A64_LDRB(dst, src, tmp), ctx); 634 break; 635 case BPF_DW: 636 emit(A64_LDR64(dst, src, tmp), ctx); 637 break; 638 } 639 break; 640 641 /* ST: *(size *)(dst + off) = imm */ 642 case BPF_ST | BPF_MEM | BPF_W: 643 case BPF_ST | BPF_MEM | BPF_H: 644 case BPF_ST | BPF_MEM | BPF_B: 645 case BPF_ST | BPF_MEM | BPF_DW: 646 /* Load imm to a register then store it */ 647 emit_a64_mov_i(1, tmp2, off, ctx); 648 emit_a64_mov_i(1, tmp, imm, ctx); 649 switch (BPF_SIZE(code)) { 650 case BPF_W: 651 emit(A64_STR32(tmp, dst, tmp2), ctx); 652 break; 653 case BPF_H: 654 emit(A64_STRH(tmp, dst, tmp2), ctx); 655 break; 656 case BPF_B: 657 emit(A64_STRB(tmp, dst, tmp2), ctx); 658 break; 659 case BPF_DW: 660 emit(A64_STR64(tmp, dst, tmp2), ctx); 661 break; 662 } 663 break; 664 665 /* STX: *(size *)(dst + off) = src */ 666 case BPF_STX | BPF_MEM | BPF_W: 667 case BPF_STX | BPF_MEM | BPF_H: 668 case BPF_STX | BPF_MEM | BPF_B: 669 case BPF_STX | BPF_MEM | BPF_DW: 670 emit_a64_mov_i(1, tmp, off, ctx); 671 switch (BPF_SIZE(code)) { 672 case BPF_W: 673 emit(A64_STR32(src, dst, tmp), ctx); 674 break; 675 case BPF_H: 676 emit(A64_STRH(src, dst, tmp), ctx); 677 break; 678 case BPF_B: 679 emit(A64_STRB(src, dst, tmp), ctx); 680 break; 681 case BPF_DW: 682 emit(A64_STR64(src, dst, tmp), ctx); 683 break; 684 } 685 break; 686 /* STX XADD: lock *(u32 *)(dst + off) += src */ 687 case BPF_STX | BPF_XADD | BPF_W: 688 /* STX XADD: lock *(u64 *)(dst + off) += src */ 689 case BPF_STX | BPF_XADD | BPF_DW: 690 emit_a64_mov_i(1, tmp, off, ctx); 691 emit(A64_ADD(1, tmp, tmp, dst), ctx); 692 emit(A64_PRFM(tmp, PST, L1, STRM), ctx); 693 emit(A64_LDXR(isdw, tmp2, tmp), ctx); 694 emit(A64_ADD(isdw, tmp2, tmp2, src), ctx); 695 emit(A64_STXR(isdw, tmp2, tmp, tmp3), ctx); 696 jmp_offset = -3; 697 check_imm19(jmp_offset); 698 emit(A64_CBNZ(0, tmp3, jmp_offset), ctx); 699 break; 700 701 /* R0 = ntohx(*(size *)(((struct sk_buff *)R6)->data + imm)) */ 702 case BPF_LD | BPF_ABS | BPF_W: 703 case BPF_LD | BPF_ABS | BPF_H: 704 case BPF_LD | BPF_ABS | BPF_B: 705 /* R0 = ntohx(*(size *)(((struct sk_buff *)R6)->data + src + imm)) */ 706 case BPF_LD | BPF_IND | BPF_W: 707 case BPF_LD | BPF_IND | BPF_H: 708 case BPF_LD | BPF_IND | BPF_B: 709 { 710 const u8 r0 = bpf2a64[BPF_REG_0]; /* r0 = return value */ 711 const u8 r6 = bpf2a64[BPF_REG_6]; /* r6 = pointer to sk_buff */ 712 const u8 fp = bpf2a64[BPF_REG_FP]; 713 const u8 r1 = bpf2a64[BPF_REG_1]; /* r1: struct sk_buff *skb */ 714 const u8 r2 = bpf2a64[BPF_REG_2]; /* r2: int k */ 715 const u8 r3 = bpf2a64[BPF_REG_3]; /* r3: unsigned int size */ 716 const u8 r4 = bpf2a64[BPF_REG_4]; /* r4: void *buffer */ 717 const u8 r5 = bpf2a64[BPF_REG_5]; /* r5: void *(*func)(...) */ 718 int size; 719 720 emit(A64_MOV(1, r1, r6), ctx); 721 emit_a64_mov_i(0, r2, imm, ctx); 722 if (BPF_MODE(code) == BPF_IND) 723 emit(A64_ADD(0, r2, r2, src), ctx); 724 switch (BPF_SIZE(code)) { 725 case BPF_W: 726 size = 4; 727 break; 728 case BPF_H: 729 size = 2; 730 break; 731 case BPF_B: 732 size = 1; 733 break; 734 default: 735 return -EINVAL; 736 } 737 emit_a64_mov_i64(r3, size, ctx); 738 emit(A64_SUB_I(1, r4, fp, ctx->stack_size), ctx); 739 emit_a64_mov_i64(r5, (unsigned long)bpf_load_pointer, ctx); 740 emit(A64_BLR(r5), ctx); 741 emit(A64_MOV(1, r0, A64_R(0)), ctx); 742 743 jmp_offset = epilogue_offset(ctx); 744 check_imm19(jmp_offset); 745 emit(A64_CBZ(1, r0, jmp_offset), ctx); 746 emit(A64_MOV(1, r5, r0), ctx); 747 switch (BPF_SIZE(code)) { 748 case BPF_W: 749 emit(A64_LDR32(r0, r5, A64_ZR), ctx); 750 #ifndef CONFIG_CPU_BIG_ENDIAN 751 emit(A64_REV32(0, r0, r0), ctx); 752 #endif 753 break; 754 case BPF_H: 755 emit(A64_LDRH(r0, r5, A64_ZR), ctx); 756 #ifndef CONFIG_CPU_BIG_ENDIAN 757 emit(A64_REV16(0, r0, r0), ctx); 758 #endif 759 break; 760 case BPF_B: 761 emit(A64_LDRB(r0, r5, A64_ZR), ctx); 762 break; 763 } 764 break; 765 } 766 default: 767 pr_err_once("unknown opcode %02x\n", code); 768 return -EINVAL; 769 } 770 771 return 0; 772 } 773 774 static int build_body(struct jit_ctx *ctx) 775 { 776 const struct bpf_prog *prog = ctx->prog; 777 int i; 778 779 for (i = 0; i < prog->len; i++) { 780 const struct bpf_insn *insn = &prog->insnsi[i]; 781 int ret; 782 783 ret = build_insn(insn, ctx); 784 if (ret > 0) { 785 i++; 786 if (ctx->image == NULL) 787 ctx->offset[i] = ctx->idx; 788 continue; 789 } 790 if (ctx->image == NULL) 791 ctx->offset[i] = ctx->idx; 792 if (ret) 793 return ret; 794 } 795 796 return 0; 797 } 798 799 static int validate_code(struct jit_ctx *ctx) 800 { 801 int i; 802 803 for (i = 0; i < ctx->idx; i++) { 804 u32 a64_insn = le32_to_cpu(ctx->image[i]); 805 806 if (a64_insn == AARCH64_BREAK_FAULT) 807 return -1; 808 } 809 810 return 0; 811 } 812 813 static inline void bpf_flush_icache(void *start, void *end) 814 { 815 flush_icache_range((unsigned long)start, (unsigned long)end); 816 } 817 818 struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) 819 { 820 struct bpf_prog *tmp, *orig_prog = prog; 821 struct bpf_binary_header *header; 822 bool tmp_blinded = false; 823 struct jit_ctx ctx; 824 int image_size; 825 u8 *image_ptr; 826 827 if (!bpf_jit_enable) 828 return orig_prog; 829 830 tmp = bpf_jit_blind_constants(prog); 831 /* If blinding was requested and we failed during blinding, 832 * we must fall back to the interpreter. 833 */ 834 if (IS_ERR(tmp)) 835 return orig_prog; 836 if (tmp != prog) { 837 tmp_blinded = true; 838 prog = tmp; 839 } 840 841 memset(&ctx, 0, sizeof(ctx)); 842 ctx.prog = prog; 843 844 ctx.offset = kcalloc(prog->len, sizeof(int), GFP_KERNEL); 845 if (ctx.offset == NULL) { 846 prog = orig_prog; 847 goto out; 848 } 849 850 /* 1. Initial fake pass to compute ctx->idx. */ 851 852 /* Fake pass to fill in ctx->offset. */ 853 if (build_body(&ctx)) { 854 prog = orig_prog; 855 goto out_off; 856 } 857 858 if (build_prologue(&ctx)) { 859 prog = orig_prog; 860 goto out_off; 861 } 862 863 ctx.epilogue_offset = ctx.idx; 864 build_epilogue(&ctx); 865 866 /* Now we know the actual image size. */ 867 image_size = sizeof(u32) * ctx.idx; 868 header = bpf_jit_binary_alloc(image_size, &image_ptr, 869 sizeof(u32), jit_fill_hole); 870 if (header == NULL) { 871 prog = orig_prog; 872 goto out_off; 873 } 874 875 /* 2. Now, the actual pass. */ 876 877 ctx.image = (__le32 *)image_ptr; 878 ctx.idx = 0; 879 880 build_prologue(&ctx); 881 882 if (build_body(&ctx)) { 883 bpf_jit_binary_free(header); 884 prog = orig_prog; 885 goto out_off; 886 } 887 888 build_epilogue(&ctx); 889 890 /* 3. Extra pass to validate JITed code. */ 891 if (validate_code(&ctx)) { 892 bpf_jit_binary_free(header); 893 prog = orig_prog; 894 goto out_off; 895 } 896 897 /* And we're done. */ 898 if (bpf_jit_enable > 1) 899 bpf_jit_dump(prog->len, image_size, 2, ctx.image); 900 901 bpf_flush_icache(header, ctx.image + ctx.idx); 902 903 bpf_jit_binary_lock_ro(header); 904 prog->bpf_func = (void *)ctx.image; 905 prog->jited = 1; 906 prog->jited_len = image_size; 907 908 out_off: 909 kfree(ctx.offset); 910 out: 911 if (tmp_blinded) 912 bpf_jit_prog_release_other(prog, prog == orig_prog ? 913 tmp : orig_prog); 914 return prog; 915 } 916