Training courses

Kernel and Embedded Linux

Bootlin training courses

Embedded Linux, kernel,
Yocto Project, Buildroot, real-time,
graphics, boot time, debugging...

Bootlin logo

Elixir Cross Referencer

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
//===-- BPFAsmParser.cpp - Parse BPF assembly to MCInst instructions --===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#include "MCTargetDesc/BPFMCTargetDesc.h"
#include "TargetInfo/BPFTargetInfo.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCParser/MCAsmLexer.h"
#include "llvm/MC/MCParser/MCParsedAsmOperand.h"
#include "llvm/MC/MCParser/MCTargetAsmParser.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/TargetRegistry.h"

using namespace llvm;

namespace {
struct BPFOperand;

class BPFAsmParser : public MCTargetAsmParser {

  SMLoc getLoc() const { return getParser().getTok().getLoc(); }

  bool PreMatchCheck(OperandVector &Operands);

  bool MatchAndEmitInstruction(SMLoc IDLoc, unsigned &Opcode,
                               OperandVector &Operands, MCStreamer &Out,
                               uint64_t &ErrorInfo,
                               bool MatchingInlineAsm) override;

  bool ParseRegister(unsigned &RegNo, SMLoc &StartLoc, SMLoc &EndLoc) override;
  OperandMatchResultTy tryParseRegister(unsigned &RegNo, SMLoc &StartLoc,
                                        SMLoc &EndLoc) override;

  bool ParseInstruction(ParseInstructionInfo &Info, StringRef Name,
                        SMLoc NameLoc, OperandVector &Operands) override;

  bool ParseDirective(AsmToken DirectiveID) override;

  // "=" is used as assignment operator for assembly statment, so can't be used
  // for symbol assignment.
  bool equalIsAsmAssignment() override { return false; }
  // "*" is used for dereferencing memory that it will be the start of
  // statement.
  bool starIsStartOfStatement() override { return true; }

#define GET_ASSEMBLER_HEADER
#include "BPFGenAsmMatcher.inc"

  OperandMatchResultTy parseImmediate(OperandVector &Operands);
  OperandMatchResultTy parseRegister(OperandVector &Operands);
  OperandMatchResultTy parseOperandAsOperator(OperandVector &Operands);

public:
  enum BPFMatchResultTy {
    Match_Dummy = FIRST_TARGET_MATCH_RESULT_TY,
#define GET_OPERAND_DIAGNOSTIC_TYPES
#include "BPFGenAsmMatcher.inc"
#undef GET_OPERAND_DIAGNOSTIC_TYPES
  };

  BPFAsmParser(const MCSubtargetInfo &STI, MCAsmParser &Parser,
               const MCInstrInfo &MII, const MCTargetOptions &Options)
      : MCTargetAsmParser(Options, STI, MII) {
    setAvailableFeatures(ComputeAvailableFeatures(STI.getFeatureBits()));
  }
};

/// BPFOperand - Instances of this class represent a parsed machine
/// instruction
struct BPFOperand : public MCParsedAsmOperand {

  enum KindTy {
    Token,
    Register,
    Immediate,
  } Kind;

  struct RegOp {
    unsigned RegNum;
  };

  struct ImmOp {
    const MCExpr *Val;
  };

  SMLoc StartLoc, EndLoc;
  union {
    StringRef Tok;
    RegOp Reg;
    ImmOp Imm;
  };

  BPFOperand(KindTy K) : MCParsedAsmOperand(), Kind(K) {}

public:
  BPFOperand(const BPFOperand &o) : MCParsedAsmOperand() {
    Kind = o.Kind;
    StartLoc = o.StartLoc;
    EndLoc = o.EndLoc;

    switch (Kind) {
    case Register:
      Reg = o.Reg;
      break;
    case Immediate:
      Imm = o.Imm;
      break;
    case Token:
      Tok = o.Tok;
      break;
    }
  }

  bool isToken() const override { return Kind == Token; }
  bool isReg() const override { return Kind == Register; }
  bool isImm() const override { return Kind == Immediate; }
  bool isMem() const override { return false; }

  bool isConstantImm() const {
    return isImm() && isa<MCConstantExpr>(getImm());
  }

  int64_t getConstantImm() const {
    const MCExpr *Val = getImm();
    return static_cast<const MCConstantExpr *>(Val)->getValue();
  }

  bool isSImm12() const {
    return (isConstantImm() && isInt<12>(getConstantImm()));
  }

  /// getStartLoc - Gets location of the first token of this operand
  SMLoc getStartLoc() const override { return StartLoc; }
  /// getEndLoc - Gets location of the last token of this operand
  SMLoc getEndLoc() const override { return EndLoc; }

  unsigned getReg() const override {
    assert(Kind == Register && "Invalid type access!");
    return Reg.RegNum;
  }

  const MCExpr *getImm() const {
    assert(Kind == Immediate && "Invalid type access!");
    return Imm.Val;
  }

  StringRef getToken() const {
    assert(Kind == Token && "Invalid type access!");
    return Tok;
  }

  void print(raw_ostream &OS) const override {
    switch (Kind) {
    case Immediate:
      OS << *getImm();
      break;
    case Register:
      OS << "<register x";
      OS << getReg() << ">";
      break;
    case Token:
      OS << "'" << getToken() << "'";
      break;
    }
  }

  void addExpr(MCInst &Inst, const MCExpr *Expr) const {
    assert(Expr && "Expr shouldn't be null!");

    if (auto *CE = dyn_cast<MCConstantExpr>(Expr))
      Inst.addOperand(MCOperand::createImm(CE->getValue()));
    else
      Inst.addOperand(MCOperand::createExpr(Expr));
  }

  // Used by the TableGen Code
  void addRegOperands(MCInst &Inst, unsigned N) const {
    assert(N == 1 && "Invalid number of operands!");
    Inst.addOperand(MCOperand::createReg(getReg()));
  }

  void addImmOperands(MCInst &Inst, unsigned N) const {
    assert(N == 1 && "Invalid number of operands!");
    addExpr(Inst, getImm());
  }

  static std::unique_ptr<BPFOperand> createToken(StringRef Str, SMLoc S) {
    auto Op = std::make_unique<BPFOperand>(Token);
    Op->Tok = Str;
    Op->StartLoc = S;
    Op->EndLoc = S;
    return Op;
  }

  static std::unique_ptr<BPFOperand> createReg(unsigned RegNo, SMLoc S,
                                               SMLoc E) {
    auto Op = std::make_unique<BPFOperand>(Register);
    Op->Reg.RegNum = RegNo;
    Op->StartLoc = S;
    Op->EndLoc = E;
    return Op;
  }

  static std::unique_ptr<BPFOperand> createImm(const MCExpr *Val, SMLoc S,
                                               SMLoc E) {
    auto Op = std::make_unique<BPFOperand>(Immediate);
    Op->Imm.Val = Val;
    Op->StartLoc = S;
    Op->EndLoc = E;
    return Op;
  }

  // Identifiers that can be used at the start of a statment.
  static bool isValidIdAtStart(StringRef Name) {
    return StringSwitch<bool>(Name.lower())
        .Case("if", true)
        .Case("call", true)
        .Case("goto", true)
        .Case("*", true)
        .Case("exit", true)
        .Case("lock", true)
        .Case("ld_pseudo", true)
        .Default(false);
  }

  // Identifiers that can be used in the middle of a statment.
  static bool isValidIdInMiddle(StringRef Name) {
    return StringSwitch<bool>(Name.lower())
        .Case("u64", true)
        .Case("u32", true)
        .Case("u16", true)
        .Case("u8", true)
        .Case("be64", true)
        .Case("be32", true)
        .Case("be16", true)
        .Case("le64", true)
        .Case("le32", true)
        .Case("le16", true)
        .Case("goto", true)
        .Case("ll", true)
        .Case("skb", true)
        .Case("s", true)
        .Default(false);
  }
};
} // end anonymous namespace.

#define GET_REGISTER_MATCHER
#define GET_MATCHER_IMPLEMENTATION
#include "BPFGenAsmMatcher.inc"

bool BPFAsmParser::PreMatchCheck(OperandVector &Operands) {

  if (Operands.size() == 4) {
    // check "reg1 = -reg2" and "reg1 = be16/be32/be64/le16/le32/le64 reg2",
    // reg1 must be the same as reg2
    BPFOperand &Op0 = (BPFOperand &)*Operands[0];
    BPFOperand &Op1 = (BPFOperand &)*Operands[1];
    BPFOperand &Op2 = (BPFOperand &)*Operands[2];
    BPFOperand &Op3 = (BPFOperand &)*Operands[3];
    if (Op0.isReg() && Op1.isToken() && Op2.isToken() && Op3.isReg()
        && Op1.getToken() == "="
        && (Op2.getToken() == "-" || Op2.getToken() == "be16"
            || Op2.getToken() == "be32" || Op2.getToken() == "be64"
            || Op2.getToken() == "le16" || Op2.getToken() == "le32"
            || Op2.getToken() == "le64")
        && Op0.getReg() != Op3.getReg())
      return true;
  }

  return false;
}

bool BPFAsmParser::MatchAndEmitInstruction(SMLoc IDLoc, unsigned &Opcode,
                                           OperandVector &Operands,
                                           MCStreamer &Out, uint64_t &ErrorInfo,
                                           bool MatchingInlineAsm) {
  MCInst Inst;
  SMLoc ErrorLoc;

  if (PreMatchCheck(Operands))
    return Error(IDLoc, "additional inst constraint not met");

  switch (MatchInstructionImpl(Operands, Inst, ErrorInfo, MatchingInlineAsm)) {
  default:
    break;
  case Match_Success:
    Inst.setLoc(IDLoc);
    Out.emitInstruction(Inst, getSTI());
    return false;
  case Match_MissingFeature:
    return Error(IDLoc, "instruction use requires an option to be enabled");
  case Match_MnemonicFail:
    return Error(IDLoc, "unrecognized instruction mnemonic");
  case Match_InvalidOperand:
    ErrorLoc = IDLoc;

    if (ErrorInfo != ~0U) {
      if (ErrorInfo >= Operands.size())
        return Error(ErrorLoc, "too few operands for instruction");

      ErrorLoc = ((BPFOperand &)*Operands[ErrorInfo]).getStartLoc();

      if (ErrorLoc == SMLoc())
        ErrorLoc = IDLoc;
    }

    return Error(ErrorLoc, "invalid operand for instruction");
  }

  llvm_unreachable("Unknown match type detected!");
}

bool BPFAsmParser::ParseRegister(unsigned &RegNo, SMLoc &StartLoc,
                                 SMLoc &EndLoc) {
  if (tryParseRegister(RegNo, StartLoc, EndLoc) != MatchOperand_Success)
    return Error(StartLoc, "invalid register name");
  return false;
}

OperandMatchResultTy BPFAsmParser::tryParseRegister(unsigned &RegNo,
                                                    SMLoc &StartLoc,
                                                    SMLoc &EndLoc) {
  const AsmToken &Tok = getParser().getTok();
  StartLoc = Tok.getLoc();
  EndLoc = Tok.getEndLoc();
  RegNo = 0;
  StringRef Name = getLexer().getTok().getIdentifier();

  if (!MatchRegisterName(Name)) {
    getParser().Lex(); // Eat identifier token.
    return MatchOperand_Success;
  }

  return MatchOperand_NoMatch;
}

OperandMatchResultTy
BPFAsmParser::parseOperandAsOperator(OperandVector &Operands) {
  SMLoc S = getLoc();

  if (getLexer().getKind() == AsmToken::Identifier) {
    StringRef Name = getLexer().getTok().getIdentifier();

    if (BPFOperand::isValidIdInMiddle(Name)) {
      getLexer().Lex();
      Operands.push_back(BPFOperand::createToken(Name, S));
      return MatchOperand_Success;
    }

    return MatchOperand_NoMatch;
  }

  switch (getLexer().getKind()) {
  case AsmToken::Minus:
  case AsmToken::Plus: {
    if (getLexer().peekTok().is(AsmToken::Integer))
      return MatchOperand_NoMatch;
    LLVM_FALLTHROUGH;
  }

  case AsmToken::Equal:
  case AsmToken::Greater:
  case AsmToken::Less:
  case AsmToken::Pipe:
  case AsmToken::Star:
  case AsmToken::LParen:
  case AsmToken::RParen:
  case AsmToken::LBrac:
  case AsmToken::RBrac:
  case AsmToken::Slash:
  case AsmToken::Amp:
  case AsmToken::Percent:
  case AsmToken::Caret: {
    StringRef Name = getLexer().getTok().getString();
    getLexer().Lex();
    Operands.push_back(BPFOperand::createToken(Name, S));

    return MatchOperand_Success;
  }

  case AsmToken::EqualEqual:
  case AsmToken::ExclaimEqual:
  case AsmToken::GreaterEqual:
  case AsmToken::GreaterGreater:
  case AsmToken::LessEqual:
  case AsmToken::LessLess: {
    Operands.push_back(BPFOperand::createToken(
        getLexer().getTok().getString().substr(0, 1), S));
    Operands.push_back(BPFOperand::createToken(
        getLexer().getTok().getString().substr(1, 1), S));
    getLexer().Lex();

    return MatchOperand_Success;
  }

  default:
    break;
  }

  return MatchOperand_NoMatch;
}

OperandMatchResultTy BPFAsmParser::parseRegister(OperandVector &Operands) {
  SMLoc S = getLoc();
  SMLoc E = SMLoc::getFromPointer(S.getPointer() - 1);

  switch (getLexer().getKind()) {
  default:
    return MatchOperand_NoMatch;
  case AsmToken::Identifier:
    StringRef Name = getLexer().getTok().getIdentifier();
    unsigned RegNo = MatchRegisterName(Name);

    if (RegNo == 0)
      return MatchOperand_NoMatch;

    getLexer().Lex();
    Operands.push_back(BPFOperand::createReg(RegNo, S, E));
  }
  return MatchOperand_Success;
}

OperandMatchResultTy BPFAsmParser::parseImmediate(OperandVector &Operands) {
  switch (getLexer().getKind()) {
  default:
    return MatchOperand_NoMatch;
  case AsmToken::LParen:
  case AsmToken::Minus:
  case AsmToken::Plus:
  case AsmToken::Integer:
  case AsmToken::String:
  case AsmToken::Identifier:
    break;
  }

  const MCExpr *IdVal;
  SMLoc S = getLoc();

  if (getParser().parseExpression(IdVal))
    return MatchOperand_ParseFail;

  SMLoc E = SMLoc::getFromPointer(S.getPointer() - 1);
  Operands.push_back(BPFOperand::createImm(IdVal, S, E));

  return MatchOperand_Success;
}

/// ParseInstruction - Parse an BPF instruction which is in BPF verifier
/// format.
bool BPFAsmParser::ParseInstruction(ParseInstructionInfo &Info, StringRef Name,
                                    SMLoc NameLoc, OperandVector &Operands) {
  // The first operand could be either register or actually an operator.
  unsigned RegNo = MatchRegisterName(Name);

  if (RegNo != 0) {
    SMLoc E = SMLoc::getFromPointer(NameLoc.getPointer() - 1);
    Operands.push_back(BPFOperand::createReg(RegNo, NameLoc, E));
  } else if (BPFOperand::isValidIdAtStart (Name))
    Operands.push_back(BPFOperand::createToken(Name, NameLoc));
  else
    return Error(NameLoc, "invalid register/token name");

  while (!getLexer().is(AsmToken::EndOfStatement)) {
    // Attempt to parse token as operator
    if (parseOperandAsOperator(Operands) == MatchOperand_Success)
      continue;

    // Attempt to parse token as register
    if (parseRegister(Operands) == MatchOperand_Success)
      continue;

    // Attempt to parse token as an immediate
    if (parseImmediate(Operands) != MatchOperand_Success) {
      SMLoc Loc = getLexer().getLoc();
      return Error(Loc, "unexpected token");
    }
  }

  if (getLexer().isNot(AsmToken::EndOfStatement)) {
    SMLoc Loc = getLexer().getLoc();

    getParser().eatToEndOfStatement();

    return Error(Loc, "unexpected token");
  }

  // Consume the EndOfStatement.
  getParser().Lex();
  return false;
}

bool BPFAsmParser::ParseDirective(AsmToken DirectiveID) { return true; }

extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeBPFAsmParser() {
  RegisterMCAsmParser<BPFAsmParser> X(getTheBPFTarget());
  RegisterMCAsmParser<BPFAsmParser> Y(getTheBPFleTarget());
  RegisterMCAsmParser<BPFAsmParser> Z(getTheBPFbeTarget());
}