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/slab.h> 25 26 #include <asm/byteorder.h> 27 #include <asm/cacheflush.h> 28 #include <asm/debug-monitors.h> 29 #include <asm/set_memory.h> 30 31 #include "bpf_jit.h" 32 33 #define TMP_REG_1 (MAX_BPF_JIT_REG + 0) 34 #define TMP_REG_2 (MAX_BPF_JIT_REG + 1) 35 #define TCALL_CNT (MAX_BPF_JIT_REG + 2) 36 #define TMP_REG_3 (MAX_BPF_JIT_REG + 3) 37 38 /* Map BPF registers to A64 registers */ 39 static const int bpf2a64[] = { 40 /* return value from in-kernel function, and exit value from eBPF */ 41 [BPF_REG_0] = A64_R(7), 42 /* arguments from eBPF program to in-kernel function */ 43 [BPF_REG_1] = A64_R(0), 44 [BPF_REG_2] = A64_R(1), 45 [BPF_REG_3] = A64_R(2), 46 [BPF_REG_4] = A64_R(3), 47 [BPF_REG_5] = A64_R(4), 48 /* callee saved registers that in-kernel function will preserve */ 49 [BPF_REG_6] = A64_R(19), 50 [BPF_REG_7] = A64_R(20), 51 [BPF_REG_8] = A64_R(21), 52 [BPF_REG_9] = A64_R(22), 53 /* read-only frame pointer to access stack */ 54 [BPF_REG_FP] = A64_R(25), 55 /* temporary registers for internal BPF JIT */ 56 [TMP_REG_1] = A64_R(10), 57 [TMP_REG_2] = A64_R(11), 58 [TMP_REG_3] = A64_R(12), 59 /* tail_call_cnt */ 60 [TCALL_CNT] = A64_R(26), 61 /* temporary register for blinding constants */ 62 [BPF_REG_AX] = A64_R(9), 63 }; 64 65 struct jit_ctx { 66 const struct bpf_prog *prog; 67 int idx; 68 int epilogue_offset; 69 int *offset; 70 __le32 *image; 71 u32 stack_size; 72 }; 73 74 static inline void emit(const u32 insn, struct jit_ctx *ctx) 75 { 76 if (ctx->image != NULL) 77 ctx->image[ctx->idx] = cpu_to_le32(insn); 78 79 ctx->idx++; 80 } 81 82 static inline void emit_a64_mov_i(const int is64, const int reg, 83 const s32 val, struct jit_ctx *ctx) 84 { 85 u16 hi = val >> 16; 86 u16 lo = val & 0xffff; 87 88 if (hi & 0x8000) { 89 if (hi == 0xffff) { 90 emit(A64_MOVN(is64, reg, (u16)~lo, 0), ctx); 91 } else { 92 emit(A64_MOVN(is64, reg, (u16)~hi, 16), ctx); 93 if (lo != 0xffff) 94 emit(A64_MOVK(is64, reg, lo, 0), ctx); 95 } 96 } else { 97 emit(A64_MOVZ(is64, reg, lo, 0), ctx); 98 if (hi) 99 emit(A64_MOVK(is64, reg, hi, 16), ctx); 100 } 101 } 102 103 static int i64_i16_blocks(const u64 val, bool inverse) 104 { 105 return (((val >> 0) & 0xffff) != (inverse ? 0xffff : 0x0000)) + 106 (((val >> 16) & 0xffff) != (inverse ? 0xffff : 0x0000)) + 107 (((val >> 32) & 0xffff) != (inverse ? 0xffff : 0x0000)) + 108 (((val >> 48) & 0xffff) != (inverse ? 0xffff : 0x0000)); 109 } 110 111 static inline void emit_a64_mov_i64(const int reg, const u64 val, 112 struct jit_ctx *ctx) 113 { 114 u64 nrm_tmp = val, rev_tmp = ~val; 115 bool inverse; 116 int shift; 117 118 if (!(nrm_tmp >> 32)) 119 return emit_a64_mov_i(0, reg, (u32)val, ctx); 120 121 inverse = i64_i16_blocks(nrm_tmp, true) < i64_i16_blocks(nrm_tmp, false); 122 shift = max(round_down((inverse ? (fls64(rev_tmp) - 1) : 123 (fls64(nrm_tmp) - 1)), 16), 0); 124 if (inverse) 125 emit(A64_MOVN(1, reg, (rev_tmp >> shift) & 0xffff, shift), ctx); 126 else 127 emit(A64_MOVZ(1, reg, (nrm_tmp >> shift) & 0xffff, shift), ctx); 128 shift -= 16; 129 while (shift >= 0) { 130 if (((nrm_tmp >> shift) & 0xffff) != (inverse ? 0xffff : 0x0000)) 131 emit(A64_MOVK(1, reg, (nrm_tmp >> shift) & 0xffff, shift), ctx); 132 shift -= 16; 133 } 134 } 135 136 /* 137 * Kernel addresses in the vmalloc space use at most 48 bits, and the 138 * remaining bits are guaranteed to be 0x1. So we can compose the address 139 * with a fixed length movn/movk/movk sequence. 140 */ 141 static inline void emit_addr_mov_i64(const int reg, const u64 val, 142 struct jit_ctx *ctx) 143 { 144 u64 tmp = val; 145 int shift = 0; 146 147 emit(A64_MOVN(1, reg, ~tmp & 0xffff, shift), ctx); 148 while (shift < 32) { 149 tmp >>= 16; 150 shift += 16; 151 emit(A64_MOVK(1, reg, tmp & 0xffff, shift), ctx); 152 } 153 } 154 155 static inline int bpf2a64_offset(int bpf_to, int bpf_from, 156 const struct jit_ctx *ctx) 157 { 158 int to = ctx->offset[bpf_to]; 159 /* -1 to account for the Branch instruction */ 160 int from = ctx->offset[bpf_from] - 1; 161 162 return to - from; 163 } 164 165 static void jit_fill_hole(void *area, unsigned int size) 166 { 167 __le32 *ptr; 168 /* We are guaranteed to have aligned memory. */ 169 for (ptr = area; size >= sizeof(u32); size -= sizeof(u32)) 170 *ptr++ = cpu_to_le32(AARCH64_BREAK_FAULT); 171 } 172 173 static inline int epilogue_offset(const struct jit_ctx *ctx) 174 { 175 int to = ctx->epilogue_offset; 176 int from = ctx->idx; 177 178 return to - from; 179 } 180 181 /* Stack must be multiples of 16B */ 182 #define STACK_ALIGN(sz) (((sz) + 15) & ~15) 183 184 /* Tail call offset to jump into */ 185 #define PROLOGUE_OFFSET 7 186 187 static int build_prologue(struct jit_ctx *ctx, bool ebpf_from_cbpf) 188 { 189 const struct bpf_prog *prog = ctx->prog; 190 const u8 r6 = bpf2a64[BPF_REG_6]; 191 const u8 r7 = bpf2a64[BPF_REG_7]; 192 const u8 r8 = bpf2a64[BPF_REG_8]; 193 const u8 r9 = bpf2a64[BPF_REG_9]; 194 const u8 fp = bpf2a64[BPF_REG_FP]; 195 const u8 tcc = bpf2a64[TCALL_CNT]; 196 const int idx0 = ctx->idx; 197 int cur_offset; 198 199 /* 200 * BPF prog stack layout 201 * 202 * high 203 * original A64_SP => 0:+-----+ BPF prologue 204 * |FP/LR| 205 * current A64_FP => -16:+-----+ 206 * | ... | callee saved registers 207 * BPF fp register => -64:+-----+ <= (BPF_FP) 208 * | | 209 * | ... | BPF prog stack 210 * | | 211 * +-----+ <= (BPF_FP - prog->aux->stack_depth) 212 * |RSVD | padding 213 * current A64_SP => +-----+ <= (BPF_FP - ctx->stack_size) 214 * | | 215 * | ... | Function call stack 216 * | | 217 * +-----+ 218 * low 219 * 220 */ 221 222 /* Save FP and LR registers to stay align with ARM64 AAPCS */ 223 emit(A64_PUSH(A64_FP, A64_LR, A64_SP), ctx); 224 emit(A64_MOV(1, A64_FP, A64_SP), ctx); 225 226 /* Save callee-saved registers */ 227 emit(A64_PUSH(r6, r7, A64_SP), ctx); 228 emit(A64_PUSH(r8, r9, A64_SP), ctx); 229 emit(A64_PUSH(fp, tcc, A64_SP), ctx); 230 231 /* Set up BPF prog stack base register */ 232 emit(A64_MOV(1, fp, A64_SP), ctx); 233 234 if (!ebpf_from_cbpf) { 235 /* Initialize tail_call_cnt */ 236 emit(A64_MOVZ(1, tcc, 0, 0), ctx); 237 238 cur_offset = ctx->idx - idx0; 239 if (cur_offset != PROLOGUE_OFFSET) { 240 pr_err_once("PROLOGUE_OFFSET = %d, expected %d!\n", 241 cur_offset, PROLOGUE_OFFSET); 242 return -1; 243 } 244 } 245 246 ctx->stack_size = STACK_ALIGN(prog->aux->stack_depth); 247 248 /* Set up function call stack */ 249 emit(A64_SUB_I(1, A64_SP, A64_SP, ctx->stack_size), ctx); 250 return 0; 251 } 252 253 static int out_offset = -1; /* initialized on the first pass of build_body() */ 254 static int emit_bpf_tail_call(struct jit_ctx *ctx) 255 { 256 /* bpf_tail_call(void *prog_ctx, struct bpf_array *array, u64 index) */ 257 const u8 r2 = bpf2a64[BPF_REG_2]; 258 const u8 r3 = bpf2a64[BPF_REG_3]; 259 260 const u8 tmp = bpf2a64[TMP_REG_1]; 261 const u8 prg = bpf2a64[TMP_REG_2]; 262 const u8 tcc = bpf2a64[TCALL_CNT]; 263 const int idx0 = ctx->idx; 264 #define cur_offset (ctx->idx - idx0) 265 #define jmp_offset (out_offset - (cur_offset)) 266 size_t off; 267 268 /* if (index >= array->map.max_entries) 269 * goto out; 270 */ 271 off = offsetof(struct bpf_array, map.max_entries); 272 emit_a64_mov_i64(tmp, off, ctx); 273 emit(A64_LDR32(tmp, r2, tmp), ctx); 274 emit(A64_MOV(0, r3, r3), ctx); 275 emit(A64_CMP(0, r3, tmp), ctx); 276 emit(A64_B_(A64_COND_CS, jmp_offset), ctx); 277 278 /* if (tail_call_cnt > MAX_TAIL_CALL_CNT) 279 * goto out; 280 * tail_call_cnt++; 281 */ 282 emit_a64_mov_i64(tmp, MAX_TAIL_CALL_CNT, ctx); 283 emit(A64_CMP(1, tcc, tmp), ctx); 284 emit(A64_B_(A64_COND_HI, jmp_offset), ctx); 285 emit(A64_ADD_I(1, tcc, tcc, 1), ctx); 286 287 /* prog = array->ptrs[index]; 288 * if (prog == NULL) 289 * goto out; 290 */ 291 off = offsetof(struct bpf_array, ptrs); 292 emit_a64_mov_i64(tmp, off, ctx); 293 emit(A64_ADD(1, tmp, r2, tmp), ctx); 294 emit(A64_LSL(1, prg, r3, 3), ctx); 295 emit(A64_LDR64(prg, tmp, prg), ctx); 296 emit(A64_CBZ(1, prg, jmp_offset), ctx); 297 298 /* goto *(prog->bpf_func + prologue_offset); */ 299 off = offsetof(struct bpf_prog, bpf_func); 300 emit_a64_mov_i64(tmp, off, ctx); 301 emit(A64_LDR64(tmp, prg, tmp), ctx); 302 emit(A64_ADD_I(1, tmp, tmp, sizeof(u32) * PROLOGUE_OFFSET), ctx); 303 emit(A64_ADD_I(1, A64_SP, A64_SP, ctx->stack_size), ctx); 304 emit(A64_BR(tmp), ctx); 305 306 /* out: */ 307 if (out_offset == -1) 308 out_offset = cur_offset; 309 if (cur_offset != out_offset) { 310 pr_err_once("tail_call out_offset = %d, expected %d!\n", 311 cur_offset, out_offset); 312 return -1; 313 } 314 return 0; 315 #undef cur_offset 316 #undef jmp_offset 317 } 318 319 static void build_epilogue(struct jit_ctx *ctx) 320 { 321 const u8 r0 = bpf2a64[BPF_REG_0]; 322 const u8 r6 = bpf2a64[BPF_REG_6]; 323 const u8 r7 = bpf2a64[BPF_REG_7]; 324 const u8 r8 = bpf2a64[BPF_REG_8]; 325 const u8 r9 = bpf2a64[BPF_REG_9]; 326 const u8 fp = bpf2a64[BPF_REG_FP]; 327 328 /* We're done with BPF stack */ 329 emit(A64_ADD_I(1, A64_SP, A64_SP, ctx->stack_size), ctx); 330 331 /* Restore fs (x25) and x26 */ 332 emit(A64_POP(fp, A64_R(26), A64_SP), ctx); 333 334 /* Restore callee-saved register */ 335 emit(A64_POP(r8, r9, A64_SP), ctx); 336 emit(A64_POP(r6, r7, A64_SP), ctx); 337 338 /* Restore FP/LR registers */ 339 emit(A64_POP(A64_FP, A64_LR, A64_SP), ctx); 340 341 /* Set return value */ 342 emit(A64_MOV(1, A64_R(0), r0), ctx); 343 344 emit(A64_RET(A64_LR), ctx); 345 } 346 347 /* JITs an eBPF instruction. 348 * Returns: 349 * 0 - successfully JITed an 8-byte eBPF instruction. 350 * >0 - successfully JITed a 16-byte eBPF instruction. 351 * <0 - failed to JIT. 352 */ 353 static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, 354 bool extra_pass) 355 { 356 const u8 code = insn->code; 357 const u8 dst = bpf2a64[insn->dst_reg]; 358 const u8 src = bpf2a64[insn->src_reg]; 359 const u8 tmp = bpf2a64[TMP_REG_1]; 360 const u8 tmp2 = bpf2a64[TMP_REG_2]; 361 const u8 tmp3 = bpf2a64[TMP_REG_3]; 362 const s16 off = insn->off; 363 const s32 imm = insn->imm; 364 const int i = insn - ctx->prog->insnsi; 365 const bool is64 = BPF_CLASS(code) == BPF_ALU64; 366 const bool isdw = BPF_SIZE(code) == BPF_DW; 367 u8 jmp_cond; 368 s32 jmp_offset; 369 370 #define check_imm(bits, imm) do { \ 371 if ((((imm) > 0) && ((imm) >> (bits))) || \ 372 (((imm) < 0) && (~(imm) >> (bits)))) { \ 373 pr_info("[%2d] imm=%d(0x%x) out of range\n", \ 374 i, imm, imm); \ 375 return -EINVAL; \ 376 } \ 377 } while (0) 378 #define check_imm19(imm) check_imm(19, imm) 379 #define check_imm26(imm) check_imm(26, imm) 380 381 switch (code) { 382 /* dst = src */ 383 case BPF_ALU | BPF_MOV | BPF_X: 384 case BPF_ALU64 | BPF_MOV | BPF_X: 385 emit(A64_MOV(is64, dst, src), ctx); 386 break; 387 /* dst = dst OP src */ 388 case BPF_ALU | BPF_ADD | BPF_X: 389 case BPF_ALU64 | BPF_ADD | BPF_X: 390 emit(A64_ADD(is64, dst, dst, src), ctx); 391 break; 392 case BPF_ALU | BPF_SUB | BPF_X: 393 case BPF_ALU64 | BPF_SUB | BPF_X: 394 emit(A64_SUB(is64, dst, dst, src), ctx); 395 break; 396 case BPF_ALU | BPF_AND | BPF_X: 397 case BPF_ALU64 | BPF_AND | BPF_X: 398 emit(A64_AND(is64, dst, dst, src), ctx); 399 break; 400 case BPF_ALU | BPF_OR | BPF_X: 401 case BPF_ALU64 | BPF_OR | BPF_X: 402 emit(A64_ORR(is64, dst, dst, src), ctx); 403 break; 404 case BPF_ALU | BPF_XOR | BPF_X: 405 case BPF_ALU64 | BPF_XOR | BPF_X: 406 emit(A64_EOR(is64, dst, dst, src), ctx); 407 break; 408 case BPF_ALU | BPF_MUL | BPF_X: 409 case BPF_ALU64 | BPF_MUL | BPF_X: 410 emit(A64_MUL(is64, dst, dst, src), ctx); 411 break; 412 case BPF_ALU | BPF_DIV | BPF_X: 413 case BPF_ALU64 | BPF_DIV | BPF_X: 414 case BPF_ALU | BPF_MOD | BPF_X: 415 case BPF_ALU64 | BPF_MOD | BPF_X: 416 switch (BPF_OP(code)) { 417 case BPF_DIV: 418 emit(A64_UDIV(is64, dst, dst, src), ctx); 419 break; 420 case BPF_MOD: 421 emit(A64_UDIV(is64, tmp, dst, src), ctx); 422 emit(A64_MUL(is64, tmp, tmp, src), ctx); 423 emit(A64_SUB(is64, dst, dst, tmp), ctx); 424 break; 425 } 426 break; 427 case BPF_ALU | BPF_LSH | BPF_X: 428 case BPF_ALU64 | BPF_LSH | BPF_X: 429 emit(A64_LSLV(is64, dst, dst, src), ctx); 430 break; 431 case BPF_ALU | BPF_RSH | BPF_X: 432 case BPF_ALU64 | BPF_RSH | BPF_X: 433 emit(A64_LSRV(is64, dst, dst, src), ctx); 434 break; 435 case BPF_ALU | BPF_ARSH | BPF_X: 436 case BPF_ALU64 | BPF_ARSH | BPF_X: 437 emit(A64_ASRV(is64, dst, dst, src), ctx); 438 break; 439 /* dst = -dst */ 440 case BPF_ALU | BPF_NEG: 441 case BPF_ALU64 | BPF_NEG: 442 emit(A64_NEG(is64, dst, dst), ctx); 443 break; 444 /* dst = BSWAP##imm(dst) */ 445 case BPF_ALU | BPF_END | BPF_FROM_LE: 446 case BPF_ALU | BPF_END | BPF_FROM_BE: 447 #ifdef CONFIG_CPU_BIG_ENDIAN 448 if (BPF_SRC(code) == BPF_FROM_BE) 449 goto emit_bswap_uxt; 450 #else /* !CONFIG_CPU_BIG_ENDIAN */ 451 if (BPF_SRC(code) == BPF_FROM_LE) 452 goto emit_bswap_uxt; 453 #endif 454 switch (imm) { 455 case 16: 456 emit(A64_REV16(is64, dst, dst), ctx); 457 /* zero-extend 16 bits into 64 bits */ 458 emit(A64_UXTH(is64, dst, dst), ctx); 459 break; 460 case 32: 461 emit(A64_REV32(is64, dst, dst), ctx); 462 /* upper 32 bits already cleared */ 463 break; 464 case 64: 465 emit(A64_REV64(dst, dst), ctx); 466 break; 467 } 468 break; 469 emit_bswap_uxt: 470 switch (imm) { 471 case 16: 472 /* zero-extend 16 bits into 64 bits */ 473 emit(A64_UXTH(is64, dst, dst), ctx); 474 break; 475 case 32: 476 /* zero-extend 32 bits into 64 bits */ 477 emit(A64_UXTW(is64, dst, dst), ctx); 478 break; 479 case 64: 480 /* nop */ 481 break; 482 } 483 break; 484 /* dst = imm */ 485 case BPF_ALU | BPF_MOV | BPF_K: 486 case BPF_ALU64 | BPF_MOV | BPF_K: 487 emit_a64_mov_i(is64, dst, imm, ctx); 488 break; 489 /* dst = dst OP imm */ 490 case BPF_ALU | BPF_ADD | BPF_K: 491 case BPF_ALU64 | BPF_ADD | BPF_K: 492 emit_a64_mov_i(is64, tmp, imm, ctx); 493 emit(A64_ADD(is64, dst, dst, tmp), ctx); 494 break; 495 case BPF_ALU | BPF_SUB | BPF_K: 496 case BPF_ALU64 | BPF_SUB | BPF_K: 497 emit_a64_mov_i(is64, tmp, imm, ctx); 498 emit(A64_SUB(is64, dst, dst, tmp), ctx); 499 break; 500 case BPF_ALU | BPF_AND | BPF_K: 501 case BPF_ALU64 | BPF_AND | BPF_K: 502 emit_a64_mov_i(is64, tmp, imm, ctx); 503 emit(A64_AND(is64, dst, dst, tmp), ctx); 504 break; 505 case BPF_ALU | BPF_OR | BPF_K: 506 case BPF_ALU64 | BPF_OR | BPF_K: 507 emit_a64_mov_i(is64, tmp, imm, ctx); 508 emit(A64_ORR(is64, dst, dst, tmp), ctx); 509 break; 510 case BPF_ALU | BPF_XOR | BPF_K: 511 case BPF_ALU64 | BPF_XOR | BPF_K: 512 emit_a64_mov_i(is64, tmp, imm, ctx); 513 emit(A64_EOR(is64, dst, dst, tmp), ctx); 514 break; 515 case BPF_ALU | BPF_MUL | BPF_K: 516 case BPF_ALU64 | BPF_MUL | BPF_K: 517 emit_a64_mov_i(is64, tmp, imm, ctx); 518 emit(A64_MUL(is64, dst, dst, tmp), ctx); 519 break; 520 case BPF_ALU | BPF_DIV | BPF_K: 521 case BPF_ALU64 | BPF_DIV | BPF_K: 522 emit_a64_mov_i(is64, tmp, imm, ctx); 523 emit(A64_UDIV(is64, dst, dst, tmp), ctx); 524 break; 525 case BPF_ALU | BPF_MOD | BPF_K: 526 case BPF_ALU64 | BPF_MOD | BPF_K: 527 emit_a64_mov_i(is64, tmp2, imm, ctx); 528 emit(A64_UDIV(is64, tmp, dst, tmp2), ctx); 529 emit(A64_MUL(is64, tmp, tmp, tmp2), ctx); 530 emit(A64_SUB(is64, dst, dst, tmp), ctx); 531 break; 532 case BPF_ALU | BPF_LSH | BPF_K: 533 case BPF_ALU64 | BPF_LSH | BPF_K: 534 emit(A64_LSL(is64, dst, dst, imm), ctx); 535 break; 536 case BPF_ALU | BPF_RSH | BPF_K: 537 case BPF_ALU64 | BPF_RSH | BPF_K: 538 emit(A64_LSR(is64, dst, dst, imm), ctx); 539 break; 540 case BPF_ALU | BPF_ARSH | BPF_K: 541 case BPF_ALU64 | BPF_ARSH | BPF_K: 542 emit(A64_ASR(is64, dst, dst, imm), ctx); 543 break; 544 545 /* JUMP off */ 546 case BPF_JMP | BPF_JA: 547 jmp_offset = bpf2a64_offset(i + off, i, ctx); 548 check_imm26(jmp_offset); 549 emit(A64_B(jmp_offset), ctx); 550 break; 551 /* IF (dst COND src) JUMP off */ 552 case BPF_JMP | BPF_JEQ | BPF_X: 553 case BPF_JMP | BPF_JGT | BPF_X: 554 case BPF_JMP | BPF_JLT | BPF_X: 555 case BPF_JMP | BPF_JGE | BPF_X: 556 case BPF_JMP | BPF_JLE | BPF_X: 557 case BPF_JMP | BPF_JNE | BPF_X: 558 case BPF_JMP | BPF_JSGT | BPF_X: 559 case BPF_JMP | BPF_JSLT | BPF_X: 560 case BPF_JMP | BPF_JSGE | BPF_X: 561 case BPF_JMP | BPF_JSLE | BPF_X: 562 emit(A64_CMP(1, dst, src), ctx); 563 emit_cond_jmp: 564 jmp_offset = bpf2a64_offset(i + off, i, ctx); 565 check_imm19(jmp_offset); 566 switch (BPF_OP(code)) { 567 case BPF_JEQ: 568 jmp_cond = A64_COND_EQ; 569 break; 570 case BPF_JGT: 571 jmp_cond = A64_COND_HI; 572 break; 573 case BPF_JLT: 574 jmp_cond = A64_COND_CC; 575 break; 576 case BPF_JGE: 577 jmp_cond = A64_COND_CS; 578 break; 579 case BPF_JLE: 580 jmp_cond = A64_COND_LS; 581 break; 582 case BPF_JSET: 583 case BPF_JNE: 584 jmp_cond = A64_COND_NE; 585 break; 586 case BPF_JSGT: 587 jmp_cond = A64_COND_GT; 588 break; 589 case BPF_JSLT: 590 jmp_cond = A64_COND_LT; 591 break; 592 case BPF_JSGE: 593 jmp_cond = A64_COND_GE; 594 break; 595 case BPF_JSLE: 596 jmp_cond = A64_COND_LE; 597 break; 598 default: 599 return -EFAULT; 600 } 601 emit(A64_B_(jmp_cond, jmp_offset), ctx); 602 break; 603 case BPF_JMP | BPF_JSET | BPF_X: 604 emit(A64_TST(1, dst, src), ctx); 605 goto emit_cond_jmp; 606 /* IF (dst COND imm) JUMP off */ 607 case BPF_JMP | BPF_JEQ | BPF_K: 608 case BPF_JMP | BPF_JGT | BPF_K: 609 case BPF_JMP | BPF_JLT | BPF_K: 610 case BPF_JMP | BPF_JGE | BPF_K: 611 case BPF_JMP | BPF_JLE | BPF_K: 612 case BPF_JMP | BPF_JNE | BPF_K: 613 case BPF_JMP | BPF_JSGT | BPF_K: 614 case BPF_JMP | BPF_JSLT | BPF_K: 615 case BPF_JMP | BPF_JSGE | BPF_K: 616 case BPF_JMP | BPF_JSLE | BPF_K: 617 emit_a64_mov_i(1, tmp, imm, ctx); 618 emit(A64_CMP(1, dst, tmp), ctx); 619 goto emit_cond_jmp; 620 case BPF_JMP | BPF_JSET | BPF_K: 621 emit_a64_mov_i(1, tmp, imm, ctx); 622 emit(A64_TST(1, dst, tmp), ctx); 623 goto emit_cond_jmp; 624 /* function call */ 625 case BPF_JMP | BPF_CALL: 626 { 627 const u8 r0 = bpf2a64[BPF_REG_0]; 628 bool func_addr_fixed; 629 u64 func_addr; 630 int ret; 631 632 ret = bpf_jit_get_func_addr(ctx->prog, insn, extra_pass, 633 &func_addr, &func_addr_fixed); 634 if (ret < 0) 635 return ret; 636 emit_addr_mov_i64(tmp, func_addr, ctx); 637 emit(A64_BLR(tmp), ctx); 638 emit(A64_MOV(1, r0, A64_R(0)), ctx); 639 break; 640 } 641 /* tail call */ 642 case BPF_JMP | BPF_TAIL_CALL: 643 if (emit_bpf_tail_call(ctx)) 644 return -EFAULT; 645 break; 646 /* function return */ 647 case BPF_JMP | BPF_EXIT: 648 /* Optimization: when last instruction is EXIT, 649 simply fallthrough to epilogue. */ 650 if (i == ctx->prog->len - 1) 651 break; 652 jmp_offset = epilogue_offset(ctx); 653 check_imm26(jmp_offset); 654 emit(A64_B(jmp_offset), ctx); 655 break; 656 657 /* dst = imm64 */ 658 case BPF_LD | BPF_IMM | BPF_DW: 659 { 660 const struct bpf_insn insn1 = insn[1]; 661 u64 imm64; 662 663 imm64 = (u64)insn1.imm << 32 | (u32)imm; 664 emit_a64_mov_i64(dst, imm64, ctx); 665 666 return 1; 667 } 668 669 /* LDX: dst = *(size *)(src + off) */ 670 case BPF_LDX | BPF_MEM | BPF_W: 671 case BPF_LDX | BPF_MEM | BPF_H: 672 case BPF_LDX | BPF_MEM | BPF_B: 673 case BPF_LDX | BPF_MEM | BPF_DW: 674 emit_a64_mov_i(1, tmp, off, ctx); 675 switch (BPF_SIZE(code)) { 676 case BPF_W: 677 emit(A64_LDR32(dst, src, tmp), ctx); 678 break; 679 case BPF_H: 680 emit(A64_LDRH(dst, src, tmp), ctx); 681 break; 682 case BPF_B: 683 emit(A64_LDRB(dst, src, tmp), ctx); 684 break; 685 case BPF_DW: 686 emit(A64_LDR64(dst, src, tmp), ctx); 687 break; 688 } 689 break; 690 691 /* ST: *(size *)(dst + off) = imm */ 692 case BPF_ST | BPF_MEM | BPF_W: 693 case BPF_ST | BPF_MEM | BPF_H: 694 case BPF_ST | BPF_MEM | BPF_B: 695 case BPF_ST | BPF_MEM | BPF_DW: 696 /* Load imm to a register then store it */ 697 emit_a64_mov_i(1, tmp2, off, ctx); 698 emit_a64_mov_i(1, tmp, imm, ctx); 699 switch (BPF_SIZE(code)) { 700 case BPF_W: 701 emit(A64_STR32(tmp, dst, tmp2), ctx); 702 break; 703 case BPF_H: 704 emit(A64_STRH(tmp, dst, tmp2), ctx); 705 break; 706 case BPF_B: 707 emit(A64_STRB(tmp, dst, tmp2), ctx); 708 break; 709 case BPF_DW: 710 emit(A64_STR64(tmp, dst, tmp2), ctx); 711 break; 712 } 713 break; 714 715 /* STX: *(size *)(dst + off) = src */ 716 case BPF_STX | BPF_MEM | BPF_W: 717 case BPF_STX | BPF_MEM | BPF_H: 718 case BPF_STX | BPF_MEM | BPF_B: 719 case BPF_STX | BPF_MEM | BPF_DW: 720 emit_a64_mov_i(1, tmp, off, ctx); 721 switch (BPF_SIZE(code)) { 722 case BPF_W: 723 emit(A64_STR32(src, dst, tmp), ctx); 724 break; 725 case BPF_H: 726 emit(A64_STRH(src, dst, tmp), ctx); 727 break; 728 case BPF_B: 729 emit(A64_STRB(src, dst, tmp), ctx); 730 break; 731 case BPF_DW: 732 emit(A64_STR64(src, dst, tmp), ctx); 733 break; 734 } 735 break; 736 /* STX XADD: lock *(u32 *)(dst + off) += src */ 737 case BPF_STX | BPF_XADD | BPF_W: 738 /* STX XADD: lock *(u64 *)(dst + off) += src */ 739 case BPF_STX | BPF_XADD | BPF_DW: 740 emit_a64_mov_i(1, tmp, off, ctx); 741 emit(A64_ADD(1, tmp, tmp, dst), ctx); 742 emit(A64_PRFM(tmp, PST, L1, STRM), ctx); 743 emit(A64_LDXR(isdw, tmp2, tmp), ctx); 744 emit(A64_ADD(isdw, tmp2, tmp2, src), ctx); 745 emit(A64_STXR(isdw, tmp2, tmp, tmp3), ctx); 746 jmp_offset = -3; 747 check_imm19(jmp_offset); 748 emit(A64_CBNZ(0, tmp3, jmp_offset), ctx); 749 break; 750 751 default: 752 pr_err_once("unknown opcode %02x\n", code); 753 return -EINVAL; 754 } 755 756 return 0; 757 } 758 759 static int build_body(struct jit_ctx *ctx, bool extra_pass) 760 { 761 const struct bpf_prog *prog = ctx->prog; 762 int i; 763 764 for (i = 0; i < prog->len; i++) { 765 const struct bpf_insn *insn = &prog->insnsi[i]; 766 int ret; 767 768 ret = build_insn(insn, ctx, extra_pass); 769 if (ret > 0) { 770 i++; 771 if (ctx->image == NULL) 772 ctx->offset[i] = ctx->idx; 773 continue; 774 } 775 if (ctx->image == NULL) 776 ctx->offset[i] = ctx->idx; 777 if (ret) 778 return ret; 779 } 780 781 return 0; 782 } 783 784 static int validate_code(struct jit_ctx *ctx) 785 { 786 int i; 787 788 for (i = 0; i < ctx->idx; i++) { 789 u32 a64_insn = le32_to_cpu(ctx->image[i]); 790 791 if (a64_insn == AARCH64_BREAK_FAULT) 792 return -1; 793 } 794 795 return 0; 796 } 797 798 static inline void bpf_flush_icache(void *start, void *end) 799 { 800 flush_icache_range((unsigned long)start, (unsigned long)end); 801 } 802 803 struct arm64_jit_data { 804 struct bpf_binary_header *header; 805 u8 *image; 806 struct jit_ctx ctx; 807 }; 808 809 struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) 810 { 811 struct bpf_prog *tmp, *orig_prog = prog; 812 struct bpf_binary_header *header; 813 struct arm64_jit_data *jit_data; 814 bool was_classic = bpf_prog_was_classic(prog); 815 bool tmp_blinded = false; 816 bool extra_pass = false; 817 struct jit_ctx ctx; 818 int image_size; 819 u8 *image_ptr; 820 821 if (!prog->jit_requested) 822 return orig_prog; 823 824 tmp = bpf_jit_blind_constants(prog); 825 /* If blinding was requested and we failed during blinding, 826 * we must fall back to the interpreter. 827 */ 828 if (IS_ERR(tmp)) 829 return orig_prog; 830 if (tmp != prog) { 831 tmp_blinded = true; 832 prog = tmp; 833 } 834 835 jit_data = prog->aux->jit_data; 836 if (!jit_data) { 837 jit_data = kzalloc(sizeof(*jit_data), GFP_KERNEL); 838 if (!jit_data) { 839 prog = orig_prog; 840 goto out; 841 } 842 prog->aux->jit_data = jit_data; 843 } 844 if (jit_data->ctx.offset) { 845 ctx = jit_data->ctx; 846 image_ptr = jit_data->image; 847 header = jit_data->header; 848 extra_pass = true; 849 image_size = sizeof(u32) * ctx.idx; 850 goto skip_init_ctx; 851 } 852 memset(&ctx, 0, sizeof(ctx)); 853 ctx.prog = prog; 854 855 ctx.offset = kcalloc(prog->len, sizeof(int), GFP_KERNEL); 856 if (ctx.offset == NULL) { 857 prog = orig_prog; 858 goto out_off; 859 } 860 861 /* 1. Initial fake pass to compute ctx->idx. */ 862 863 /* Fake pass to fill in ctx->offset. */ 864 if (build_body(&ctx, extra_pass)) { 865 prog = orig_prog; 866 goto out_off; 867 } 868 869 if (build_prologue(&ctx, was_classic)) { 870 prog = orig_prog; 871 goto out_off; 872 } 873 874 ctx.epilogue_offset = ctx.idx; 875 build_epilogue(&ctx); 876 877 /* Now we know the actual image size. */ 878 image_size = sizeof(u32) * ctx.idx; 879 header = bpf_jit_binary_alloc(image_size, &image_ptr, 880 sizeof(u32), jit_fill_hole); 881 if (header == NULL) { 882 prog = orig_prog; 883 goto out_off; 884 } 885 886 /* 2. Now, the actual pass. */ 887 888 ctx.image = (__le32 *)image_ptr; 889 skip_init_ctx: 890 ctx.idx = 0; 891 892 build_prologue(&ctx, was_classic); 893 894 if (build_body(&ctx, extra_pass)) { 895 bpf_jit_binary_free(header); 896 prog = orig_prog; 897 goto out_off; 898 } 899 900 build_epilogue(&ctx); 901 902 /* 3. Extra pass to validate JITed code. */ 903 if (validate_code(&ctx)) { 904 bpf_jit_binary_free(header); 905 prog = orig_prog; 906 goto out_off; 907 } 908 909 /* And we're done. */ 910 if (bpf_jit_enable > 1) 911 bpf_jit_dump(prog->len, image_size, 2, ctx.image); 912 913 bpf_flush_icache(header, ctx.image + ctx.idx); 914 915 if (!prog->is_func || extra_pass) { 916 if (extra_pass && ctx.idx != jit_data->ctx.idx) { 917 pr_err_once("multi-func JIT bug %d != %d\n", 918 ctx.idx, jit_data->ctx.idx); 919 bpf_jit_binary_free(header); 920 prog->bpf_func = NULL; 921 prog->jited = 0; 922 goto out_off; 923 } 924 bpf_jit_binary_lock_ro(header); 925 } else { 926 jit_data->ctx = ctx; 927 jit_data->image = image_ptr; 928 jit_data->header = header; 929 } 930 prog->bpf_func = (void *)ctx.image; 931 prog->jited = 1; 932 prog->jited_len = image_size; 933 934 if (!prog->is_func || extra_pass) { 935 bpf_prog_fill_jited_linfo(prog, ctx.offset); 936 out_off: 937 kfree(ctx.offset); 938 kfree(jit_data); 939 prog->aux->jit_data = NULL; 940 } 941 out: 942 if (tmp_blinded) 943 bpf_jit_prog_release_other(prog, prog == orig_prog ? 944 tmp : orig_prog); 945 return prog; 946 } 947 948 void *bpf_jit_alloc_exec(unsigned long size) 949 { 950 return __vmalloc_node_range(size, PAGE_SIZE, BPF_JIT_REGION_START, 951 BPF_JIT_REGION_END, GFP_KERNEL, 952 PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE, 953 __builtin_return_address(0)); 954 } 955 956 void bpf_jit_free_exec(void *addr) 957 { 958 return vfree(addr); 959 } 960