David K. Bainbridge | 215e024 | 2017-09-05 23:18:24 -0700 | [diff] [blame] | 1 | // Copyright 2016 The Go Authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | package bpf |
| 6 | |
| 7 | import "fmt" |
| 8 | |
| 9 | // An Instruction is one instruction executed by the BPF virtual |
| 10 | // machine. |
| 11 | type Instruction interface { |
| 12 | // Assemble assembles the Instruction into a RawInstruction. |
| 13 | Assemble() (RawInstruction, error) |
| 14 | } |
| 15 | |
| 16 | // A RawInstruction is a raw BPF virtual machine instruction. |
| 17 | type RawInstruction struct { |
| 18 | // Operation to execute. |
| 19 | Op uint16 |
| 20 | // For conditional jump instructions, the number of instructions |
| 21 | // to skip if the condition is true/false. |
| 22 | Jt uint8 |
| 23 | Jf uint8 |
| 24 | // Constant parameter. The meaning depends on the Op. |
| 25 | K uint32 |
| 26 | } |
| 27 | |
| 28 | // Assemble implements the Instruction Assemble method. |
| 29 | func (ri RawInstruction) Assemble() (RawInstruction, error) { return ri, nil } |
| 30 | |
| 31 | // Disassemble parses ri into an Instruction and returns it. If ri is |
| 32 | // not recognized by this package, ri itself is returned. |
| 33 | func (ri RawInstruction) Disassemble() Instruction { |
| 34 | switch ri.Op & opMaskCls { |
| 35 | case opClsLoadA, opClsLoadX: |
| 36 | reg := Register(ri.Op & opMaskLoadDest) |
| 37 | sz := 0 |
| 38 | switch ri.Op & opMaskLoadWidth { |
| 39 | case opLoadWidth4: |
| 40 | sz = 4 |
| 41 | case opLoadWidth2: |
| 42 | sz = 2 |
| 43 | case opLoadWidth1: |
| 44 | sz = 1 |
| 45 | default: |
| 46 | return ri |
| 47 | } |
| 48 | switch ri.Op & opMaskLoadMode { |
| 49 | case opAddrModeImmediate: |
| 50 | if sz != 4 { |
| 51 | return ri |
| 52 | } |
| 53 | return LoadConstant{Dst: reg, Val: ri.K} |
| 54 | case opAddrModeScratch: |
| 55 | if sz != 4 || ri.K > 15 { |
| 56 | return ri |
| 57 | } |
| 58 | return LoadScratch{Dst: reg, N: int(ri.K)} |
| 59 | case opAddrModeAbsolute: |
| 60 | if ri.K > extOffset+0xffffffff { |
| 61 | return LoadExtension{Num: Extension(-extOffset + ri.K)} |
| 62 | } |
| 63 | return LoadAbsolute{Size: sz, Off: ri.K} |
| 64 | case opAddrModeIndirect: |
| 65 | return LoadIndirect{Size: sz, Off: ri.K} |
| 66 | case opAddrModePacketLen: |
| 67 | if sz != 4 { |
| 68 | return ri |
| 69 | } |
| 70 | return LoadExtension{Num: ExtLen} |
| 71 | case opAddrModeMemShift: |
| 72 | return LoadMemShift{Off: ri.K} |
| 73 | default: |
| 74 | return ri |
| 75 | } |
| 76 | |
| 77 | case opClsStoreA: |
| 78 | if ri.Op != opClsStoreA || ri.K > 15 { |
| 79 | return ri |
| 80 | } |
| 81 | return StoreScratch{Src: RegA, N: int(ri.K)} |
| 82 | |
| 83 | case opClsStoreX: |
| 84 | if ri.Op != opClsStoreX || ri.K > 15 { |
| 85 | return ri |
| 86 | } |
| 87 | return StoreScratch{Src: RegX, N: int(ri.K)} |
| 88 | |
| 89 | case opClsALU: |
| 90 | switch op := ALUOp(ri.Op & opMaskOperator); op { |
| 91 | case ALUOpAdd, ALUOpSub, ALUOpMul, ALUOpDiv, ALUOpOr, ALUOpAnd, ALUOpShiftLeft, ALUOpShiftRight, ALUOpMod, ALUOpXor: |
| 92 | if ri.Op&opMaskOperandSrc != 0 { |
| 93 | return ALUOpX{Op: op} |
| 94 | } |
| 95 | return ALUOpConstant{Op: op, Val: ri.K} |
| 96 | case aluOpNeg: |
| 97 | return NegateA{} |
| 98 | default: |
| 99 | return ri |
| 100 | } |
| 101 | |
| 102 | case opClsJump: |
| 103 | if ri.Op&opMaskJumpConst != opClsJump { |
| 104 | return ri |
| 105 | } |
| 106 | switch ri.Op & opMaskJumpCond { |
| 107 | case opJumpAlways: |
| 108 | return Jump{Skip: ri.K} |
| 109 | case opJumpEqual: |
| 110 | if ri.Jt == 0 { |
| 111 | return JumpIf{ |
| 112 | Cond: JumpNotEqual, |
| 113 | Val: ri.K, |
| 114 | SkipTrue: ri.Jf, |
| 115 | SkipFalse: 0, |
| 116 | } |
| 117 | } |
| 118 | return JumpIf{ |
| 119 | Cond: JumpEqual, |
| 120 | Val: ri.K, |
| 121 | SkipTrue: ri.Jt, |
| 122 | SkipFalse: ri.Jf, |
| 123 | } |
| 124 | case opJumpGT: |
| 125 | if ri.Jt == 0 { |
| 126 | return JumpIf{ |
| 127 | Cond: JumpLessOrEqual, |
| 128 | Val: ri.K, |
| 129 | SkipTrue: ri.Jf, |
| 130 | SkipFalse: 0, |
| 131 | } |
| 132 | } |
| 133 | return JumpIf{ |
| 134 | Cond: JumpGreaterThan, |
| 135 | Val: ri.K, |
| 136 | SkipTrue: ri.Jt, |
| 137 | SkipFalse: ri.Jf, |
| 138 | } |
| 139 | case opJumpGE: |
| 140 | if ri.Jt == 0 { |
| 141 | return JumpIf{ |
| 142 | Cond: JumpLessThan, |
| 143 | Val: ri.K, |
| 144 | SkipTrue: ri.Jf, |
| 145 | SkipFalse: 0, |
| 146 | } |
| 147 | } |
| 148 | return JumpIf{ |
| 149 | Cond: JumpGreaterOrEqual, |
| 150 | Val: ri.K, |
| 151 | SkipTrue: ri.Jt, |
| 152 | SkipFalse: ri.Jf, |
| 153 | } |
| 154 | case opJumpSet: |
| 155 | return JumpIf{ |
| 156 | Cond: JumpBitsSet, |
| 157 | Val: ri.K, |
| 158 | SkipTrue: ri.Jt, |
| 159 | SkipFalse: ri.Jf, |
| 160 | } |
| 161 | default: |
| 162 | return ri |
| 163 | } |
| 164 | |
| 165 | case opClsReturn: |
| 166 | switch ri.Op { |
| 167 | case opClsReturn | opRetSrcA: |
| 168 | return RetA{} |
| 169 | case opClsReturn | opRetSrcConstant: |
| 170 | return RetConstant{Val: ri.K} |
| 171 | default: |
| 172 | return ri |
| 173 | } |
| 174 | |
| 175 | case opClsMisc: |
| 176 | switch ri.Op { |
| 177 | case opClsMisc | opMiscTAX: |
| 178 | return TAX{} |
| 179 | case opClsMisc | opMiscTXA: |
| 180 | return TXA{} |
| 181 | default: |
| 182 | return ri |
| 183 | } |
| 184 | |
| 185 | default: |
| 186 | panic("unreachable") // switch is exhaustive on the bit pattern |
| 187 | } |
| 188 | } |
| 189 | |
| 190 | // LoadConstant loads Val into register Dst. |
| 191 | type LoadConstant struct { |
| 192 | Dst Register |
| 193 | Val uint32 |
| 194 | } |
| 195 | |
| 196 | // Assemble implements the Instruction Assemble method. |
| 197 | func (a LoadConstant) Assemble() (RawInstruction, error) { |
| 198 | return assembleLoad(a.Dst, 4, opAddrModeImmediate, a.Val) |
| 199 | } |
| 200 | |
| 201 | // String returns the the instruction in assembler notation. |
| 202 | func (a LoadConstant) String() string { |
| 203 | switch a.Dst { |
| 204 | case RegA: |
| 205 | return fmt.Sprintf("ld #%d", a.Val) |
| 206 | case RegX: |
| 207 | return fmt.Sprintf("ldx #%d", a.Val) |
| 208 | default: |
| 209 | return fmt.Sprintf("unknown instruction: %#v", a) |
| 210 | } |
| 211 | } |
| 212 | |
| 213 | // LoadScratch loads scratch[N] into register Dst. |
| 214 | type LoadScratch struct { |
| 215 | Dst Register |
| 216 | N int // 0-15 |
| 217 | } |
| 218 | |
| 219 | // Assemble implements the Instruction Assemble method. |
| 220 | func (a LoadScratch) Assemble() (RawInstruction, error) { |
| 221 | if a.N < 0 || a.N > 15 { |
| 222 | return RawInstruction{}, fmt.Errorf("invalid scratch slot %d", a.N) |
| 223 | } |
| 224 | return assembleLoad(a.Dst, 4, opAddrModeScratch, uint32(a.N)) |
| 225 | } |
| 226 | |
| 227 | // String returns the the instruction in assembler notation. |
| 228 | func (a LoadScratch) String() string { |
| 229 | switch a.Dst { |
| 230 | case RegA: |
| 231 | return fmt.Sprintf("ld M[%d]", a.N) |
| 232 | case RegX: |
| 233 | return fmt.Sprintf("ldx M[%d]", a.N) |
| 234 | default: |
| 235 | return fmt.Sprintf("unknown instruction: %#v", a) |
| 236 | } |
| 237 | } |
| 238 | |
| 239 | // LoadAbsolute loads packet[Off:Off+Size] as an integer value into |
| 240 | // register A. |
| 241 | type LoadAbsolute struct { |
| 242 | Off uint32 |
| 243 | Size int // 1, 2 or 4 |
| 244 | } |
| 245 | |
| 246 | // Assemble implements the Instruction Assemble method. |
| 247 | func (a LoadAbsolute) Assemble() (RawInstruction, error) { |
| 248 | return assembleLoad(RegA, a.Size, opAddrModeAbsolute, a.Off) |
| 249 | } |
| 250 | |
| 251 | // String returns the the instruction in assembler notation. |
| 252 | func (a LoadAbsolute) String() string { |
| 253 | switch a.Size { |
| 254 | case 1: // byte |
| 255 | return fmt.Sprintf("ldb [%d]", a.Off) |
| 256 | case 2: // half word |
| 257 | return fmt.Sprintf("ldh [%d]", a.Off) |
| 258 | case 4: // word |
| 259 | if a.Off > extOffset+0xffffffff { |
| 260 | return LoadExtension{Num: Extension(a.Off + 0x1000)}.String() |
| 261 | } |
| 262 | return fmt.Sprintf("ld [%d]", a.Off) |
| 263 | default: |
| 264 | return fmt.Sprintf("unknown instruction: %#v", a) |
| 265 | } |
| 266 | } |
| 267 | |
| 268 | // LoadIndirect loads packet[X+Off:X+Off+Size] as an integer value |
| 269 | // into register A. |
| 270 | type LoadIndirect struct { |
| 271 | Off uint32 |
| 272 | Size int // 1, 2 or 4 |
| 273 | } |
| 274 | |
| 275 | // Assemble implements the Instruction Assemble method. |
| 276 | func (a LoadIndirect) Assemble() (RawInstruction, error) { |
| 277 | return assembleLoad(RegA, a.Size, opAddrModeIndirect, a.Off) |
| 278 | } |
| 279 | |
| 280 | // String returns the the instruction in assembler notation. |
| 281 | func (a LoadIndirect) String() string { |
| 282 | switch a.Size { |
| 283 | case 1: // byte |
| 284 | return fmt.Sprintf("ldb [x + %d]", a.Off) |
| 285 | case 2: // half word |
| 286 | return fmt.Sprintf("ldh [x + %d]", a.Off) |
| 287 | case 4: // word |
| 288 | return fmt.Sprintf("ld [x + %d]", a.Off) |
| 289 | default: |
| 290 | return fmt.Sprintf("unknown instruction: %#v", a) |
| 291 | } |
| 292 | } |
| 293 | |
| 294 | // LoadMemShift multiplies the first 4 bits of the byte at packet[Off] |
| 295 | // by 4 and stores the result in register X. |
| 296 | // |
| 297 | // This instruction is mainly useful to load into X the length of an |
| 298 | // IPv4 packet header in a single instruction, rather than have to do |
| 299 | // the arithmetic on the header's first byte by hand. |
| 300 | type LoadMemShift struct { |
| 301 | Off uint32 |
| 302 | } |
| 303 | |
| 304 | // Assemble implements the Instruction Assemble method. |
| 305 | func (a LoadMemShift) Assemble() (RawInstruction, error) { |
| 306 | return assembleLoad(RegX, 1, opAddrModeMemShift, a.Off) |
| 307 | } |
| 308 | |
| 309 | // String returns the the instruction in assembler notation. |
| 310 | func (a LoadMemShift) String() string { |
| 311 | return fmt.Sprintf("ldx 4*([%d]&0xf)", a.Off) |
| 312 | } |
| 313 | |
| 314 | // LoadExtension invokes a linux-specific extension and stores the |
| 315 | // result in register A. |
| 316 | type LoadExtension struct { |
| 317 | Num Extension |
| 318 | } |
| 319 | |
| 320 | // Assemble implements the Instruction Assemble method. |
| 321 | func (a LoadExtension) Assemble() (RawInstruction, error) { |
| 322 | if a.Num == ExtLen { |
| 323 | return assembleLoad(RegA, 4, opAddrModePacketLen, 0) |
| 324 | } |
| 325 | return assembleLoad(RegA, 4, opAddrModeAbsolute, uint32(extOffset+a.Num)) |
| 326 | } |
| 327 | |
| 328 | // String returns the the instruction in assembler notation. |
| 329 | func (a LoadExtension) String() string { |
| 330 | switch a.Num { |
| 331 | case ExtLen: |
| 332 | return "ld #len" |
| 333 | case ExtProto: |
| 334 | return "ld #proto" |
| 335 | case ExtType: |
| 336 | return "ld #type" |
| 337 | case ExtPayloadOffset: |
| 338 | return "ld #poff" |
| 339 | case ExtInterfaceIndex: |
| 340 | return "ld #ifidx" |
| 341 | case ExtNetlinkAttr: |
| 342 | return "ld #nla" |
| 343 | case ExtNetlinkAttrNested: |
| 344 | return "ld #nlan" |
| 345 | case ExtMark: |
| 346 | return "ld #mark" |
| 347 | case ExtQueue: |
| 348 | return "ld #queue" |
| 349 | case ExtLinkLayerType: |
| 350 | return "ld #hatype" |
| 351 | case ExtRXHash: |
| 352 | return "ld #rxhash" |
| 353 | case ExtCPUID: |
| 354 | return "ld #cpu" |
| 355 | case ExtVLANTag: |
| 356 | return "ld #vlan_tci" |
| 357 | case ExtVLANTagPresent: |
| 358 | return "ld #vlan_avail" |
| 359 | case ExtVLANProto: |
| 360 | return "ld #vlan_tpid" |
| 361 | case ExtRand: |
| 362 | return "ld #rand" |
| 363 | default: |
| 364 | return fmt.Sprintf("unknown instruction: %#v", a) |
| 365 | } |
| 366 | } |
| 367 | |
| 368 | // StoreScratch stores register Src into scratch[N]. |
| 369 | type StoreScratch struct { |
| 370 | Src Register |
| 371 | N int // 0-15 |
| 372 | } |
| 373 | |
| 374 | // Assemble implements the Instruction Assemble method. |
| 375 | func (a StoreScratch) Assemble() (RawInstruction, error) { |
| 376 | if a.N < 0 || a.N > 15 { |
| 377 | return RawInstruction{}, fmt.Errorf("invalid scratch slot %d", a.N) |
| 378 | } |
| 379 | var op uint16 |
| 380 | switch a.Src { |
| 381 | case RegA: |
| 382 | op = opClsStoreA |
| 383 | case RegX: |
| 384 | op = opClsStoreX |
| 385 | default: |
| 386 | return RawInstruction{}, fmt.Errorf("invalid source register %v", a.Src) |
| 387 | } |
| 388 | |
| 389 | return RawInstruction{ |
| 390 | Op: op, |
| 391 | K: uint32(a.N), |
| 392 | }, nil |
| 393 | } |
| 394 | |
| 395 | // String returns the the instruction in assembler notation. |
| 396 | func (a StoreScratch) String() string { |
| 397 | switch a.Src { |
| 398 | case RegA: |
| 399 | return fmt.Sprintf("st M[%d]", a.N) |
| 400 | case RegX: |
| 401 | return fmt.Sprintf("stx M[%d]", a.N) |
| 402 | default: |
| 403 | return fmt.Sprintf("unknown instruction: %#v", a) |
| 404 | } |
| 405 | } |
| 406 | |
| 407 | // ALUOpConstant executes A = A <Op> Val. |
| 408 | type ALUOpConstant struct { |
| 409 | Op ALUOp |
| 410 | Val uint32 |
| 411 | } |
| 412 | |
| 413 | // Assemble implements the Instruction Assemble method. |
| 414 | func (a ALUOpConstant) Assemble() (RawInstruction, error) { |
| 415 | return RawInstruction{ |
| 416 | Op: opClsALU | opALUSrcConstant | uint16(a.Op), |
| 417 | K: a.Val, |
| 418 | }, nil |
| 419 | } |
| 420 | |
| 421 | // String returns the the instruction in assembler notation. |
| 422 | func (a ALUOpConstant) String() string { |
| 423 | switch a.Op { |
| 424 | case ALUOpAdd: |
| 425 | return fmt.Sprintf("add #%d", a.Val) |
| 426 | case ALUOpSub: |
| 427 | return fmt.Sprintf("sub #%d", a.Val) |
| 428 | case ALUOpMul: |
| 429 | return fmt.Sprintf("mul #%d", a.Val) |
| 430 | case ALUOpDiv: |
| 431 | return fmt.Sprintf("div #%d", a.Val) |
| 432 | case ALUOpMod: |
| 433 | return fmt.Sprintf("mod #%d", a.Val) |
| 434 | case ALUOpAnd: |
| 435 | return fmt.Sprintf("and #%d", a.Val) |
| 436 | case ALUOpOr: |
| 437 | return fmt.Sprintf("or #%d", a.Val) |
| 438 | case ALUOpXor: |
| 439 | return fmt.Sprintf("xor #%d", a.Val) |
| 440 | case ALUOpShiftLeft: |
| 441 | return fmt.Sprintf("lsh #%d", a.Val) |
| 442 | case ALUOpShiftRight: |
| 443 | return fmt.Sprintf("rsh #%d", a.Val) |
| 444 | default: |
| 445 | return fmt.Sprintf("unknown instruction: %#v", a) |
| 446 | } |
| 447 | } |
| 448 | |
| 449 | // ALUOpX executes A = A <Op> X |
| 450 | type ALUOpX struct { |
| 451 | Op ALUOp |
| 452 | } |
| 453 | |
| 454 | // Assemble implements the Instruction Assemble method. |
| 455 | func (a ALUOpX) Assemble() (RawInstruction, error) { |
| 456 | return RawInstruction{ |
| 457 | Op: opClsALU | opALUSrcX | uint16(a.Op), |
| 458 | }, nil |
| 459 | } |
| 460 | |
| 461 | // String returns the the instruction in assembler notation. |
| 462 | func (a ALUOpX) String() string { |
| 463 | switch a.Op { |
| 464 | case ALUOpAdd: |
| 465 | return "add x" |
| 466 | case ALUOpSub: |
| 467 | return "sub x" |
| 468 | case ALUOpMul: |
| 469 | return "mul x" |
| 470 | case ALUOpDiv: |
| 471 | return "div x" |
| 472 | case ALUOpMod: |
| 473 | return "mod x" |
| 474 | case ALUOpAnd: |
| 475 | return "and x" |
| 476 | case ALUOpOr: |
| 477 | return "or x" |
| 478 | case ALUOpXor: |
| 479 | return "xor x" |
| 480 | case ALUOpShiftLeft: |
| 481 | return "lsh x" |
| 482 | case ALUOpShiftRight: |
| 483 | return "rsh x" |
| 484 | default: |
| 485 | return fmt.Sprintf("unknown instruction: %#v", a) |
| 486 | } |
| 487 | } |
| 488 | |
| 489 | // NegateA executes A = -A. |
| 490 | type NegateA struct{} |
| 491 | |
| 492 | // Assemble implements the Instruction Assemble method. |
| 493 | func (a NegateA) Assemble() (RawInstruction, error) { |
| 494 | return RawInstruction{ |
| 495 | Op: opClsALU | uint16(aluOpNeg), |
| 496 | }, nil |
| 497 | } |
| 498 | |
| 499 | // String returns the the instruction in assembler notation. |
| 500 | func (a NegateA) String() string { |
| 501 | return fmt.Sprintf("neg") |
| 502 | } |
| 503 | |
| 504 | // Jump skips the following Skip instructions in the program. |
| 505 | type Jump struct { |
| 506 | Skip uint32 |
| 507 | } |
| 508 | |
| 509 | // Assemble implements the Instruction Assemble method. |
| 510 | func (a Jump) Assemble() (RawInstruction, error) { |
| 511 | return RawInstruction{ |
| 512 | Op: opClsJump | opJumpAlways, |
| 513 | K: a.Skip, |
| 514 | }, nil |
| 515 | } |
| 516 | |
| 517 | // String returns the the instruction in assembler notation. |
| 518 | func (a Jump) String() string { |
| 519 | return fmt.Sprintf("ja %d", a.Skip) |
| 520 | } |
| 521 | |
| 522 | // JumpIf skips the following Skip instructions in the program if A |
| 523 | // <Cond> Val is true. |
| 524 | type JumpIf struct { |
| 525 | Cond JumpTest |
| 526 | Val uint32 |
| 527 | SkipTrue uint8 |
| 528 | SkipFalse uint8 |
| 529 | } |
| 530 | |
| 531 | // Assemble implements the Instruction Assemble method. |
| 532 | func (a JumpIf) Assemble() (RawInstruction, error) { |
| 533 | var ( |
| 534 | cond uint16 |
| 535 | flip bool |
| 536 | ) |
| 537 | switch a.Cond { |
| 538 | case JumpEqual: |
| 539 | cond = opJumpEqual |
| 540 | case JumpNotEqual: |
| 541 | cond, flip = opJumpEqual, true |
| 542 | case JumpGreaterThan: |
| 543 | cond = opJumpGT |
| 544 | case JumpLessThan: |
| 545 | cond, flip = opJumpGE, true |
| 546 | case JumpGreaterOrEqual: |
| 547 | cond = opJumpGE |
| 548 | case JumpLessOrEqual: |
| 549 | cond, flip = opJumpGT, true |
| 550 | case JumpBitsSet: |
| 551 | cond = opJumpSet |
| 552 | case JumpBitsNotSet: |
| 553 | cond, flip = opJumpSet, true |
| 554 | default: |
| 555 | return RawInstruction{}, fmt.Errorf("unknown JumpTest %v", a.Cond) |
| 556 | } |
| 557 | jt, jf := a.SkipTrue, a.SkipFalse |
| 558 | if flip { |
| 559 | jt, jf = jf, jt |
| 560 | } |
| 561 | return RawInstruction{ |
| 562 | Op: opClsJump | cond, |
| 563 | Jt: jt, |
| 564 | Jf: jf, |
| 565 | K: a.Val, |
| 566 | }, nil |
| 567 | } |
| 568 | |
| 569 | // String returns the the instruction in assembler notation. |
| 570 | func (a JumpIf) String() string { |
| 571 | switch a.Cond { |
| 572 | // K == A |
| 573 | case JumpEqual: |
| 574 | return conditionalJump(a, "jeq", "jneq") |
| 575 | // K != A |
| 576 | case JumpNotEqual: |
| 577 | return fmt.Sprintf("jneq #%d,%d", a.Val, a.SkipTrue) |
| 578 | // K > A |
| 579 | case JumpGreaterThan: |
| 580 | return conditionalJump(a, "jgt", "jle") |
| 581 | // K < A |
| 582 | case JumpLessThan: |
| 583 | return fmt.Sprintf("jlt #%d,%d", a.Val, a.SkipTrue) |
| 584 | // K >= A |
| 585 | case JumpGreaterOrEqual: |
| 586 | return conditionalJump(a, "jge", "jlt") |
| 587 | // K <= A |
| 588 | case JumpLessOrEqual: |
| 589 | return fmt.Sprintf("jle #%d,%d", a.Val, a.SkipTrue) |
| 590 | // K & A != 0 |
| 591 | case JumpBitsSet: |
| 592 | if a.SkipFalse > 0 { |
| 593 | return fmt.Sprintf("jset #%d,%d,%d", a.Val, a.SkipTrue, a.SkipFalse) |
| 594 | } |
| 595 | return fmt.Sprintf("jset #%d,%d", a.Val, a.SkipTrue) |
| 596 | // K & A == 0, there is no assembler instruction for JumpBitNotSet, use JumpBitSet and invert skips |
| 597 | case JumpBitsNotSet: |
| 598 | return JumpIf{Cond: JumpBitsSet, SkipTrue: a.SkipFalse, SkipFalse: a.SkipTrue, Val: a.Val}.String() |
| 599 | default: |
| 600 | return fmt.Sprintf("unknown instruction: %#v", a) |
| 601 | } |
| 602 | } |
| 603 | |
| 604 | func conditionalJump(inst JumpIf, positiveJump, negativeJump string) string { |
| 605 | if inst.SkipTrue > 0 { |
| 606 | if inst.SkipFalse > 0 { |
| 607 | return fmt.Sprintf("%s #%d,%d,%d", positiveJump, inst.Val, inst.SkipTrue, inst.SkipFalse) |
| 608 | } |
| 609 | return fmt.Sprintf("%s #%d,%d", positiveJump, inst.Val, inst.SkipTrue) |
| 610 | } |
| 611 | return fmt.Sprintf("%s #%d,%d", negativeJump, inst.Val, inst.SkipFalse) |
| 612 | } |
| 613 | |
| 614 | // RetA exits the BPF program, returning the value of register A. |
| 615 | type RetA struct{} |
| 616 | |
| 617 | // Assemble implements the Instruction Assemble method. |
| 618 | func (a RetA) Assemble() (RawInstruction, error) { |
| 619 | return RawInstruction{ |
| 620 | Op: opClsReturn | opRetSrcA, |
| 621 | }, nil |
| 622 | } |
| 623 | |
| 624 | // String returns the the instruction in assembler notation. |
| 625 | func (a RetA) String() string { |
| 626 | return fmt.Sprintf("ret a") |
| 627 | } |
| 628 | |
| 629 | // RetConstant exits the BPF program, returning a constant value. |
| 630 | type RetConstant struct { |
| 631 | Val uint32 |
| 632 | } |
| 633 | |
| 634 | // Assemble implements the Instruction Assemble method. |
| 635 | func (a RetConstant) Assemble() (RawInstruction, error) { |
| 636 | return RawInstruction{ |
| 637 | Op: opClsReturn | opRetSrcConstant, |
| 638 | K: a.Val, |
| 639 | }, nil |
| 640 | } |
| 641 | |
| 642 | // String returns the the instruction in assembler notation. |
| 643 | func (a RetConstant) String() string { |
| 644 | return fmt.Sprintf("ret #%d", a.Val) |
| 645 | } |
| 646 | |
| 647 | // TXA copies the value of register X to register A. |
| 648 | type TXA struct{} |
| 649 | |
| 650 | // Assemble implements the Instruction Assemble method. |
| 651 | func (a TXA) Assemble() (RawInstruction, error) { |
| 652 | return RawInstruction{ |
| 653 | Op: opClsMisc | opMiscTXA, |
| 654 | }, nil |
| 655 | } |
| 656 | |
| 657 | // String returns the the instruction in assembler notation. |
| 658 | func (a TXA) String() string { |
| 659 | return fmt.Sprintf("txa") |
| 660 | } |
| 661 | |
| 662 | // TAX copies the value of register A to register X. |
| 663 | type TAX struct{} |
| 664 | |
| 665 | // Assemble implements the Instruction Assemble method. |
| 666 | func (a TAX) Assemble() (RawInstruction, error) { |
| 667 | return RawInstruction{ |
| 668 | Op: opClsMisc | opMiscTAX, |
| 669 | }, nil |
| 670 | } |
| 671 | |
| 672 | // String returns the the instruction in assembler notation. |
| 673 | func (a TAX) String() string { |
| 674 | return fmt.Sprintf("tax") |
| 675 | } |
| 676 | |
| 677 | func assembleLoad(dst Register, loadSize int, mode uint16, k uint32) (RawInstruction, error) { |
| 678 | var ( |
| 679 | cls uint16 |
| 680 | sz uint16 |
| 681 | ) |
| 682 | switch dst { |
| 683 | case RegA: |
| 684 | cls = opClsLoadA |
| 685 | case RegX: |
| 686 | cls = opClsLoadX |
| 687 | default: |
| 688 | return RawInstruction{}, fmt.Errorf("invalid target register %v", dst) |
| 689 | } |
| 690 | switch loadSize { |
| 691 | case 1: |
| 692 | sz = opLoadWidth1 |
| 693 | case 2: |
| 694 | sz = opLoadWidth2 |
| 695 | case 4: |
| 696 | sz = opLoadWidth4 |
| 697 | default: |
| 698 | return RawInstruction{}, fmt.Errorf("invalid load byte length %d", sz) |
| 699 | } |
| 700 | return RawInstruction{ |
| 701 | Op: cls | sz | mode, |
| 702 | K: k, |
| 703 | }, nil |
| 704 | } |