1 //===-- BPFAsmParser.cpp - Parse BPF assembly to MCInst instructions --===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #include "MCTargetDesc/BPFMCTargetDesc.h" 10 #include "TargetInfo/BPFTargetInfo.h" 11 #include "llvm/ADT/STLExtras.h" 12 #include "llvm/ADT/StringSwitch.h" 13 #include "llvm/MC/MCContext.h" 14 #include "llvm/MC/MCExpr.h" 15 #include "llvm/MC/MCInst.h" 16 #include "llvm/MC/MCParser/MCAsmLexer.h" 17 #include "llvm/MC/MCParser/MCParsedAsmOperand.h" 18 #include "llvm/MC/MCParser/MCTargetAsmParser.h" 19 #include "llvm/MC/MCRegisterInfo.h" 20 #include "llvm/MC/MCStreamer.h" 21 #include "llvm/MC/MCSubtargetInfo.h" 22 #include "llvm/Support/Casting.h" 23 #include "llvm/Support/TargetRegistry.h" 24 25 using namespace llvm; 26 27 namespace { 28 struct BPFOperand; 29 30 class BPFAsmParser : public MCTargetAsmParser { 31 32 SMLoc getLoc() const { return getParser().getTok().getLoc(); } 33 34 bool PreMatchCheck(OperandVector &Operands); 35 36 bool MatchAndEmitInstruction(SMLoc IDLoc, unsigned &Opcode, 37 OperandVector &Operands, MCStreamer &Out, 38 uint64_t &ErrorInfo, 39 bool MatchingInlineAsm) override; 40 41 bool ParseRegister(unsigned &RegNo, SMLoc &StartLoc, SMLoc &EndLoc) override; 42 OperandMatchResultTy tryParseRegister(unsigned &RegNo, SMLoc &StartLoc, 43 SMLoc &EndLoc) override; 44 45 bool ParseInstruction(ParseInstructionInfo &Info, StringRef Name, 46 SMLoc NameLoc, OperandVector &Operands) override; 47 48 bool ParseDirective(AsmToken DirectiveID) override; 49 50 // "=" is used as assignment operator for assembly statment, so can't be used 51 // for symbol assignment. 52 bool equalIsAsmAssignment() override { return false; } 53 // "*" is used for dereferencing memory that it will be the start of 54 // statement. 55 bool starIsStartOfStatement() override { return true; } 56 57 #define GET_ASSEMBLER_HEADER 58 #include "BPFGenAsmMatcher.inc" 59 60 OperandMatchResultTy parseImmediate(OperandVector &Operands); 61 OperandMatchResultTy parseRegister(OperandVector &Operands); 62 OperandMatchResultTy parseOperandAsOperator(OperandVector &Operands); 63 64 public: 65 enum BPFMatchResultTy { 66 Match_Dummy = FIRST_TARGET_MATCH_RESULT_TY, 67 #define GET_OPERAND_DIAGNOSTIC_TYPES 68 #include "BPFGenAsmMatcher.inc" 69 #undef GET_OPERAND_DIAGNOSTIC_TYPES 70 }; 71 72 BPFAsmParser(const MCSubtargetInfo &STI, MCAsmParser &Parser, 73 const MCInstrInfo &MII, const MCTargetOptions &Options) 74 : MCTargetAsmParser(Options, STI, MII) { 75 setAvailableFeatures(ComputeAvailableFeatures(STI.getFeatureBits())); 76 } 77 }; 78 79 /// BPFOperand - Instances of this class represent a parsed machine 80 /// instruction 81 struct BPFOperand : public MCParsedAsmOperand { 82 83 enum KindTy { 84 Token, 85 Register, 86 Immediate, 87 } Kind; 88 89 struct RegOp { 90 unsigned RegNum; 91 }; 92 93 struct ImmOp { 94 const MCExpr *Val; 95 }; 96 97 SMLoc StartLoc, EndLoc; 98 union { 99 StringRef Tok; 100 RegOp Reg; 101 ImmOp Imm; 102 }; 103 104 BPFOperand(KindTy K) : MCParsedAsmOperand(), Kind(K) {} 105 106 public: 107 BPFOperand(const BPFOperand &o) : MCParsedAsmOperand() { 108 Kind = o.Kind; 109 StartLoc = o.StartLoc; 110 EndLoc = o.EndLoc; 111 112 switch (Kind) { 113 case Register: 114 Reg = o.Reg; 115 break; 116 case Immediate: 117 Imm = o.Imm; 118 break; 119 case Token: 120 Tok = o.Tok; 121 break; 122 } 123 } 124 125 bool isToken() const override { return Kind == Token; } 126 bool isReg() const override { return Kind == Register; } 127 bool isImm() const override { return Kind == Immediate; } 128 bool isMem() const override { return false; } 129 130 bool isConstantImm() const { 131 return isImm() && isa<MCConstantExpr>(getImm()); 132 } 133 134 int64_t getConstantImm() const { 135 const MCExpr *Val = getImm(); 136 return static_cast<const MCConstantExpr *>(Val)->getValue(); 137 } 138 139 bool isSImm12() const { 140 return (isConstantImm() && isInt<12>(getConstantImm())); 141 } 142 143 /// getStartLoc - Gets location of the first token of this operand 144 SMLoc getStartLoc() const override { return StartLoc; } 145 /// getEndLoc - Gets location of the last token of this operand 146 SMLoc getEndLoc() const override { return EndLoc; } 147 148 unsigned getReg() const override { 149 assert(Kind == Register && "Invalid type access!"); 150 return Reg.RegNum; 151 } 152 153 const MCExpr *getImm() const { 154 assert(Kind == Immediate && "Invalid type access!"); 155 return Imm.Val; 156 } 157 158 StringRef getToken() const { 159 assert(Kind == Token && "Invalid type access!"); 160 return Tok; 161 } 162 163 void print(raw_ostream &OS) const override { 164 switch (Kind) { 165 case Immediate: 166 OS << *getImm(); 167 break; 168 case Register: 169 OS << "<register x"; 170 OS << getReg() << ">"; 171 break; 172 case Token: 173 OS << "'" << getToken() << "'"; 174 break; 175 } 176 } 177 178 void addExpr(MCInst &Inst, const MCExpr *Expr) const { 179 assert(Expr && "Expr shouldn't be null!"); 180 181 if (auto *CE = dyn_cast<MCConstantExpr>(Expr)) 182 Inst.addOperand(MCOperand::createImm(CE->getValue())); 183 else 184 Inst.addOperand(MCOperand::createExpr(Expr)); 185 } 186 187 // Used by the TableGen Code 188 void addRegOperands(MCInst &Inst, unsigned N) const { 189 assert(N == 1 && "Invalid number of operands!"); 190 Inst.addOperand(MCOperand::createReg(getReg())); 191 } 192 193 void addImmOperands(MCInst &Inst, unsigned N) const { 194 assert(N == 1 && "Invalid number of operands!"); 195 addExpr(Inst, getImm()); 196 } 197 198 static std::unique_ptr<BPFOperand> createToken(StringRef Str, SMLoc S) { 199 auto Op = std::make_unique<BPFOperand>(Token); 200 Op->Tok = Str; 201 Op->StartLoc = S; 202 Op->EndLoc = S; 203 return Op; 204 } 205 206 static std::unique_ptr<BPFOperand> createReg(unsigned RegNo, SMLoc S, 207 SMLoc E) { 208 auto Op = std::make_unique<BPFOperand>(Register); 209 Op->Reg.RegNum = RegNo; 210 Op->StartLoc = S; 211 Op->EndLoc = E; 212 return Op; 213 } 214 215 static std::unique_ptr<BPFOperand> createImm(const MCExpr *Val, SMLoc S, 216 SMLoc E) { 217 auto Op = std::make_unique<BPFOperand>(Immediate); 218 Op->Imm.Val = Val; 219 Op->StartLoc = S; 220 Op->EndLoc = E; 221 return Op; 222 } 223 224 // Identifiers that can be used at the start of a statment. 225 static bool isValidIdAtStart(StringRef Name) { 226 return StringSwitch<bool>(Name.lower()) 227 .Case("if", true) 228 .Case("call", true) 229 .Case("goto", true) 230 .Case("*", true) 231 .Case("exit", true) 232 .Case("lock", true) 233 .Case("ld_pseudo", true) 234 .Default(false); 235 } 236 237 // Identifiers that can be used in the middle of a statment. 238 static bool isValidIdInMiddle(StringRef Name) { 239 return StringSwitch<bool>(Name.lower()) 240 .Case("u64", true) 241 .Case("u32", true) 242 .Case("u16", true) 243 .Case("u8", true) 244 .Case("be64", true) 245 .Case("be32", true) 246 .Case("be16", true) 247 .Case("le64", true) 248 .Case("le32", true) 249 .Case("le16", true) 250 .Case("goto", true) 251 .Case("ll", true) 252 .Case("skb", true) 253 .Case("s", true) 254 .Default(false); 255 } 256 }; 257 } // end anonymous namespace. 258 259 #define GET_REGISTER_MATCHER 260 #define GET_MATCHER_IMPLEMENTATION 261 #include "BPFGenAsmMatcher.inc" 262 263 bool BPFAsmParser::PreMatchCheck(OperandVector &Operands) { 264 265 if (Operands.size() == 4) { 266 // check "reg1 = -reg2" and "reg1 = be16/be32/be64/le16/le32/le64 reg2", 267 // reg1 must be the same as reg2 268 BPFOperand &Op0 = (BPFOperand &)*Operands[0]; 269 BPFOperand &Op1 = (BPFOperand &)*Operands[1]; 270 BPFOperand &Op2 = (BPFOperand &)*Operands[2]; 271 BPFOperand &Op3 = (BPFOperand &)*Operands[3]; 272 if (Op0.isReg() && Op1.isToken() && Op2.isToken() && Op3.isReg() 273 && Op1.getToken() == "=" 274 && (Op2.getToken() == "-" || Op2.getToken() == "be16" 275 || Op2.getToken() == "be32" || Op2.getToken() == "be64" 276 || Op2.getToken() == "le16" || Op2.getToken() == "le32" 277 || Op2.getToken() == "le64") 278 && Op0.getReg() != Op3.getReg()) 279 return true; 280 } 281 282 return false; 283 } 284 285 bool BPFAsmParser::MatchAndEmitInstruction(SMLoc IDLoc, unsigned &Opcode, 286 OperandVector &Operands, 287 MCStreamer &Out, uint64_t &ErrorInfo, 288 bool MatchingInlineAsm) { 289 MCInst Inst; 290 SMLoc ErrorLoc; 291 292 if (PreMatchCheck(Operands)) 293 return Error(IDLoc, "additional inst constraint not met"); 294 295 switch (MatchInstructionImpl(Operands, Inst, ErrorInfo, MatchingInlineAsm)) { 296 default: 297 break; 298 case Match_Success: 299 Inst.setLoc(IDLoc); 300 Out.emitInstruction(Inst, getSTI()); 301 return false; 302 case Match_MissingFeature: 303 return Error(IDLoc, "instruction use requires an option to be enabled"); 304 case Match_MnemonicFail: 305 return Error(IDLoc, "unrecognized instruction mnemonic"); 306 case Match_InvalidOperand: 307 ErrorLoc = IDLoc; 308 309 if (ErrorInfo != ~0U) { 310 if (ErrorInfo >= Operands.size()) 311 return Error(ErrorLoc, "too few operands for instruction"); 312 313 ErrorLoc = ((BPFOperand &)*Operands[ErrorInfo]).getStartLoc(); 314 315 if (ErrorLoc == SMLoc()) 316 ErrorLoc = IDLoc; 317 } 318 319 return Error(ErrorLoc, "invalid operand for instruction"); 320 } 321 322 llvm_unreachable("Unknown match type detected!"); 323 } 324 325 bool BPFAsmParser::ParseRegister(unsigned &RegNo, SMLoc &StartLoc, 326 SMLoc &EndLoc) { 327 if (tryParseRegister(RegNo, StartLoc, EndLoc) != MatchOperand_Success) 328 return Error(StartLoc, "invalid register name"); 329 return false; 330 } 331 332 OperandMatchResultTy BPFAsmParser::tryParseRegister(unsigned &RegNo, 333 SMLoc &StartLoc, 334 SMLoc &EndLoc) { 335 const AsmToken &Tok = getParser().getTok(); 336 StartLoc = Tok.getLoc(); 337 EndLoc = Tok.getEndLoc(); 338 RegNo = 0; 339 StringRef Name = getLexer().getTok().getIdentifier(); 340 341 if (!MatchRegisterName(Name)) { 342 getParser().Lex(); // Eat identifier token. 343 return MatchOperand_Success; 344 } 345 346 return MatchOperand_NoMatch; 347 } 348 349 OperandMatchResultTy 350 BPFAsmParser::parseOperandAsOperator(OperandVector &Operands) { 351 SMLoc S = getLoc(); 352 353 if (getLexer().getKind() == AsmToken::Identifier) { 354 StringRef Name = getLexer().getTok().getIdentifier(); 355 356 if (BPFOperand::isValidIdInMiddle(Name)) { 357 getLexer().Lex(); 358 Operands.push_back(BPFOperand::createToken(Name, S)); 359 return MatchOperand_Success; 360 } 361 362 return MatchOperand_NoMatch; 363 } 364 365 switch (getLexer().getKind()) { 366 case AsmToken::Minus: 367 case AsmToken::Plus: { 368 if (getLexer().peekTok().is(AsmToken::Integer)) 369 return MatchOperand_NoMatch; 370 LLVM_FALLTHROUGH; 371 } 372 373 case AsmToken::Equal: 374 case AsmToken::Greater: 375 case AsmToken::Less: 376 case AsmToken::Pipe: 377 case AsmToken::Star: 378 case AsmToken::LParen: 379 case AsmToken::RParen: 380 case AsmToken::LBrac: 381 case AsmToken::RBrac: 382 case AsmToken::Slash: 383 case AsmToken::Amp: 384 case AsmToken::Percent: 385 case AsmToken::Caret: { 386 StringRef Name = getLexer().getTok().getString(); 387 getLexer().Lex(); 388 Operands.push_back(BPFOperand::createToken(Name, S)); 389 390 return MatchOperand_Success; 391 } 392 393 case AsmToken::EqualEqual: 394 case AsmToken::ExclaimEqual: 395 case AsmToken::GreaterEqual: 396 case AsmToken::GreaterGreater: 397 case AsmToken::LessEqual: 398 case AsmToken::LessLess: { 399 Operands.push_back(BPFOperand::createToken( 400 getLexer().getTok().getString().substr(0, 1), S)); 401 Operands.push_back(BPFOperand::createToken( 402 getLexer().getTok().getString().substr(1, 1), S)); 403 getLexer().Lex(); 404 405 return MatchOperand_Success; 406 } 407 408 default: 409 break; 410 } 411 412 return MatchOperand_NoMatch; 413 } 414 415 OperandMatchResultTy BPFAsmParser::parseRegister(OperandVector &Operands) { 416 SMLoc S = getLoc(); 417 SMLoc E = SMLoc::getFromPointer(S.getPointer() - 1); 418 419 switch (getLexer().getKind()) { 420 default: 421 return MatchOperand_NoMatch; 422 case AsmToken::Identifier: 423 StringRef Name = getLexer().getTok().getIdentifier(); 424 unsigned RegNo = MatchRegisterName(Name); 425 426 if (RegNo == 0) 427 return MatchOperand_NoMatch; 428 429 getLexer().Lex(); 430 Operands.push_back(BPFOperand::createReg(RegNo, S, E)); 431 } 432 return MatchOperand_Success; 433 } 434 435 OperandMatchResultTy BPFAsmParser::parseImmediate(OperandVector &Operands) { 436 switch (getLexer().getKind()) { 437 default: 438 return MatchOperand_NoMatch; 439 case AsmToken::LParen: 440 case AsmToken::Minus: 441 case AsmToken::Plus: 442 case AsmToken::Integer: 443 case AsmToken::String: 444 case AsmToken::Identifier: 445 break; 446 } 447 448 const MCExpr *IdVal; 449 SMLoc S = getLoc(); 450 451 if (getParser().parseExpression(IdVal)) 452 return MatchOperand_ParseFail; 453 454 SMLoc E = SMLoc::getFromPointer(S.getPointer() - 1); 455 Operands.push_back(BPFOperand::createImm(IdVal, S, E)); 456 457 return MatchOperand_Success; 458 } 459 460 /// ParseInstruction - Parse an BPF instruction which is in BPF verifier 461 /// format. 462 bool BPFAsmParser::ParseInstruction(ParseInstructionInfo &Info, StringRef Name, 463 SMLoc NameLoc, OperandVector &Operands) { 464 // The first operand could be either register or actually an operator. 465 unsigned RegNo = MatchRegisterName(Name); 466 467 if (RegNo != 0) { 468 SMLoc E = SMLoc::getFromPointer(NameLoc.getPointer() - 1); 469 Operands.push_back(BPFOperand::createReg(RegNo, NameLoc, E)); 470 } else if (BPFOperand::isValidIdAtStart (Name)) 471 Operands.push_back(BPFOperand::createToken(Name, NameLoc)); 472 else 473 return Error(NameLoc, "invalid register/token name"); 474 475 while (!getLexer().is(AsmToken::EndOfStatement)) { 476 // Attempt to parse token as operator 477 if (parseOperandAsOperator(Operands) == MatchOperand_Success) 478 continue; 479 480 // Attempt to parse token as register 481 if (parseRegister(Operands) == MatchOperand_Success) 482 continue; 483 484 // Attempt to parse token as an immediate 485 if (parseImmediate(Operands) != MatchOperand_Success) { 486 SMLoc Loc = getLexer().getLoc(); 487 return Error(Loc, "unexpected token"); 488 } 489 } 490 491 if (getLexer().isNot(AsmToken::EndOfStatement)) { 492 SMLoc Loc = getLexer().getLoc(); 493 494 getParser().eatToEndOfStatement(); 495 496 return Error(Loc, "unexpected token"); 497 } 498 499 // Consume the EndOfStatement. 500 getParser().Lex(); 501 return false; 502 } 503 504 bool BPFAsmParser::ParseDirective(AsmToken DirectiveID) { return true; } 505 506 extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeBPFAsmParser() { 507 RegisterMCAsmParser<BPFAsmParser> X(getTheBPFTarget()); 508 RegisterMCAsmParser<BPFAsmParser> Y(getTheBPFleTarget()); 509 RegisterMCAsmParser<BPFAsmParser> Z(getTheBPFbeTarget()); 510 } 511