1 //===--- RuntimeDyldChecker.cpp - RuntimeDyld tester framework --*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "llvm/ADT/STLExtras.h"
11 #include "RuntimeDyldCheckerImpl.h"
12 #include "RuntimeDyldImpl.h"
13 #include "llvm/ExecutionEngine/RuntimeDyldChecker.h"
14 #include "llvm/MC/MCContext.h"
15 #include "llvm/MC/MCDisassembler.h"
16 #include "llvm/MC/MCInst.h"
17 #include "llvm/Support/Path.h"
18 #include <cctype>
19 #include <memory>
20 
21 #define DEBUG_TYPE "rtdyld"
22 
23 using namespace llvm;
24 
25 namespace llvm {
26 
27 // Helper class that implements the language evaluated by RuntimeDyldChecker.
28 class RuntimeDyldCheckerExprEval {
29 public:
30   RuntimeDyldCheckerExprEval(const RuntimeDyldCheckerImpl &Checker,
31                              raw_ostream &ErrStream)
32       : Checker(Checker) {}
33 
34   bool evaluate(StringRef Expr) const {
35     // Expect equality expression of the form 'LHS = RHS'.
36     Expr = Expr.trim();
37     size_t EQIdx = Expr.find('=');
38 
39     ParseContext OutsideLoad(false);
40 
41     // Evaluate LHS.
42     StringRef LHSExpr = Expr.substr(0, EQIdx).rtrim();
43     StringRef RemainingExpr;
44     EvalResult LHSResult;
45     std::tie(LHSResult, RemainingExpr) =
46         evalComplexExpr(evalSimpleExpr(LHSExpr, OutsideLoad), OutsideLoad);
47     if (LHSResult.hasError())
48       return handleError(Expr, LHSResult);
49     if (RemainingExpr != "")
50       return handleError(Expr, unexpectedToken(RemainingExpr, LHSExpr, ""));
51 
52     // Evaluate RHS.
53     StringRef RHSExpr = Expr.substr(EQIdx + 1).ltrim();
54     EvalResult RHSResult;
55     std::tie(RHSResult, RemainingExpr) =
56         evalComplexExpr(evalSimpleExpr(RHSExpr, OutsideLoad), OutsideLoad);
57     if (RHSResult.hasError())
58       return handleError(Expr, RHSResult);
59     if (RemainingExpr != "")
60       return handleError(Expr, unexpectedToken(RemainingExpr, RHSExpr, ""));
61 
62     if (LHSResult.getValue() != RHSResult.getValue()) {
63       Checker.ErrStream << "Expression '" << Expr << "' is false: "
64                         << format("0x%" PRIx64, LHSResult.getValue())
65                         << " != " << format("0x%" PRIx64, RHSResult.getValue())
66                         << "\n";
67       return false;
68     }
69     return true;
70   }
71 
72 private:
73   // RuntimeDyldCheckerExprEval requires some context when parsing exprs. In
74   // particular, it needs to know whether a symbol is being evaluated in the
75   // context of a load, in which case we want the linker's local address for
76   // the symbol, or outside of a load, in which case we want the symbol's
77   // address in the remote target.
78 
79   struct ParseContext {
80     bool IsInsideLoad;
81     ParseContext(bool IsInsideLoad) : IsInsideLoad(IsInsideLoad) {}
82   };
83 
84   const RuntimeDyldCheckerImpl &Checker;
85 
86   enum class BinOpToken : unsigned {
87     Invalid,
88     Add,
89     Sub,
90     BitwiseAnd,
91     BitwiseOr,
92     ShiftLeft,
93     ShiftRight
94   };
95 
96   class EvalResult {
97   public:
98     EvalResult() : Value(0), ErrorMsg("") {}
99     EvalResult(uint64_t Value) : Value(Value), ErrorMsg("") {}
100     EvalResult(std::string ErrorMsg) : Value(0), ErrorMsg(ErrorMsg) {}
101     uint64_t getValue() const { return Value; }
102     bool hasError() const { return ErrorMsg != ""; }
103     const std::string &getErrorMsg() const { return ErrorMsg; }
104 
105   private:
106     uint64_t Value;
107     std::string ErrorMsg;
108   };
109 
110   StringRef getTokenForError(StringRef Expr) const {
111     if (Expr.empty())
112       return "";
113 
114     StringRef Token, Remaining;
115     if (isalpha(Expr[0]))
116       std::tie(Token, Remaining) = parseSymbol(Expr);
117     else if (isdigit(Expr[0]))
118       std::tie(Token, Remaining) = parseNumberString(Expr);
119     else {
120       unsigned TokLen = 1;
121       if (Expr.startswith("<<") || Expr.startswith(">>"))
122         TokLen = 2;
123       Token = Expr.substr(0, TokLen);
124     }
125     return Token;
126   }
127 
128   EvalResult unexpectedToken(StringRef TokenStart, StringRef SubExpr,
129                              StringRef ErrText) const {
130     std::string ErrorMsg("Encountered unexpected token '");
131     ErrorMsg += getTokenForError(TokenStart);
132     if (SubExpr != "") {
133       ErrorMsg += "' while parsing subexpression '";
134       ErrorMsg += SubExpr;
135     }
136     ErrorMsg += "'";
137     if (ErrText != "") {
138       ErrorMsg += " ";
139       ErrorMsg += ErrText;
140     }
141     return EvalResult(std::move(ErrorMsg));
142   }
143 
144   bool handleError(StringRef Expr, const EvalResult &R) const {
145     assert(R.hasError() && "Not an error result.");
146     Checker.ErrStream << "Error evaluating expression '" << Expr
147                       << "': " << R.getErrorMsg() << "\n";
148     return false;
149   }
150 
151   std::pair<BinOpToken, StringRef> parseBinOpToken(StringRef Expr) const {
152     if (Expr.empty())
153       return std::make_pair(BinOpToken::Invalid, "");
154 
155     // Handle the two 2-character tokens.
156     if (Expr.startswith("<<"))
157       return std::make_pair(BinOpToken::ShiftLeft, Expr.substr(2).ltrim());
158     if (Expr.startswith(">>"))
159       return std::make_pair(BinOpToken::ShiftRight, Expr.substr(2).ltrim());
160 
161     // Handle one-character tokens.
162     BinOpToken Op;
163     switch (Expr[0]) {
164     default:
165       return std::make_pair(BinOpToken::Invalid, Expr);
166     case '+':
167       Op = BinOpToken::Add;
168       break;
169     case '-':
170       Op = BinOpToken::Sub;
171       break;
172     case '&':
173       Op = BinOpToken::BitwiseAnd;
174       break;
175     case '|':
176       Op = BinOpToken::BitwiseOr;
177       break;
178     }
179 
180     return std::make_pair(Op, Expr.substr(1).ltrim());
181   }
182 
183   EvalResult computeBinOpResult(BinOpToken Op, const EvalResult &LHSResult,
184                                 const EvalResult &RHSResult) const {
185     switch (Op) {
186     default:
187       llvm_unreachable("Tried to evaluate unrecognized operation.");
188     case BinOpToken::Add:
189       return EvalResult(LHSResult.getValue() + RHSResult.getValue());
190     case BinOpToken::Sub:
191       return EvalResult(LHSResult.getValue() - RHSResult.getValue());
192     case BinOpToken::BitwiseAnd:
193       return EvalResult(LHSResult.getValue() & RHSResult.getValue());
194     case BinOpToken::BitwiseOr:
195       return EvalResult(LHSResult.getValue() | RHSResult.getValue());
196     case BinOpToken::ShiftLeft:
197       return EvalResult(LHSResult.getValue() << RHSResult.getValue());
198     case BinOpToken::ShiftRight:
199       return EvalResult(LHSResult.getValue() >> RHSResult.getValue());
200     }
201   }
202 
203   // Parse a symbol and return a (string, string) pair representing the symbol
204   // name and expression remaining to be parsed.
205   std::pair<StringRef, StringRef> parseSymbol(StringRef Expr) const {
206     size_t FirstNonSymbol = Expr.find_first_not_of("0123456789"
207                                                    "abcdefghijklmnopqrstuvwxyz"
208                                                    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
209                                                    ":_.$");
210     return std::make_pair(Expr.substr(0, FirstNonSymbol),
211                           Expr.substr(FirstNonSymbol).ltrim());
212   }
213 
214   // Evaluate a call to decode_operand. Decode the instruction operand at the
215   // given symbol and get the value of the requested operand.
216   // Returns an error if the instruction cannot be decoded, or the requested
217   // operand is not an immediate.
218   // On success, retuns a pair containing the value of the operand, plus
219   // the expression remaining to be evaluated.
220   std::pair<EvalResult, StringRef> evalDecodeOperand(StringRef Expr) const {
221     if (!Expr.startswith("("))
222       return std::make_pair(unexpectedToken(Expr, Expr, "expected '('"), "");
223     StringRef RemainingExpr = Expr.substr(1).ltrim();
224     StringRef Symbol;
225     std::tie(Symbol, RemainingExpr) = parseSymbol(RemainingExpr);
226 
227     if (!Checker.isSymbolValid(Symbol))
228       return std::make_pair(
229           EvalResult(("Cannot decode unknown symbol '" + Symbol + "'").str()),
230           "");
231 
232     if (!RemainingExpr.startswith(","))
233       return std::make_pair(
234           unexpectedToken(RemainingExpr, RemainingExpr, "expected ','"), "");
235     RemainingExpr = RemainingExpr.substr(1).ltrim();
236 
237     EvalResult OpIdxExpr;
238     std::tie(OpIdxExpr, RemainingExpr) = evalNumberExpr(RemainingExpr);
239     if (OpIdxExpr.hasError())
240       return std::make_pair(OpIdxExpr, "");
241 
242     if (!RemainingExpr.startswith(")"))
243       return std::make_pair(
244           unexpectedToken(RemainingExpr, RemainingExpr, "expected ')'"), "");
245     RemainingExpr = RemainingExpr.substr(1).ltrim();
246 
247     MCInst Inst;
248     uint64_t Size;
249     if (!decodeInst(Symbol, Inst, Size))
250       return std::make_pair(
251           EvalResult(("Couldn't decode instruction at '" + Symbol + "'").str()),
252           "");
253 
254     unsigned OpIdx = OpIdxExpr.getValue();
255     if (OpIdx >= Inst.getNumOperands()) {
256       std::string ErrMsg;
257       raw_string_ostream ErrMsgStream(ErrMsg);
258       ErrMsgStream << "Invalid operand index '" << format("%i", OpIdx)
259                    << "' for instruction '" << Symbol
260                    << "'. Instruction has only "
261                    << format("%i", Inst.getNumOperands())
262                    << " operands.\nInstruction is:\n  ";
263       Inst.dump_pretty(ErrMsgStream,
264                        Checker.Disassembler->getContext().getAsmInfo(),
265                        Checker.InstPrinter);
266       return std::make_pair(EvalResult(ErrMsgStream.str()), "");
267     }
268 
269     const MCOperand &Op = Inst.getOperand(OpIdx);
270     if (!Op.isImm()) {
271       std::string ErrMsg;
272       raw_string_ostream ErrMsgStream(ErrMsg);
273       ErrMsgStream << "Operand '" << format("%i", OpIdx) << "' of instruction '"
274                    << Symbol << "' is not an immediate.\nInstruction is:\n  ";
275       Inst.dump_pretty(ErrMsgStream,
276                        Checker.Disassembler->getContext().getAsmInfo(),
277                        Checker.InstPrinter);
278 
279       return std::make_pair(EvalResult(ErrMsgStream.str()), "");
280     }
281 
282     return std::make_pair(EvalResult(Op.getImm()), RemainingExpr);
283   }
284 
285   // Evaluate a call to next_pc.
286   // Decode the instruction at the given symbol and return the following program
287   // counter.
288   // Returns an error if the instruction cannot be decoded.
289   // On success, returns a pair containing the next PC, plus of the
290   // expression remaining to be evaluated.
291   std::pair<EvalResult, StringRef> evalNextPC(StringRef Expr,
292                                               ParseContext PCtx) const {
293     if (!Expr.startswith("("))
294       return std::make_pair(unexpectedToken(Expr, Expr, "expected '('"), "");
295     StringRef RemainingExpr = Expr.substr(1).ltrim();
296     StringRef Symbol;
297     std::tie(Symbol, RemainingExpr) = parseSymbol(RemainingExpr);
298 
299     if (!Checker.isSymbolValid(Symbol))
300       return std::make_pair(
301           EvalResult(("Cannot decode unknown symbol '" + Symbol + "'").str()),
302           "");
303 
304     if (!RemainingExpr.startswith(")"))
305       return std::make_pair(
306           unexpectedToken(RemainingExpr, RemainingExpr, "expected ')'"), "");
307     RemainingExpr = RemainingExpr.substr(1).ltrim();
308 
309     MCInst Inst;
310     uint64_t InstSize;
311     if (!decodeInst(Symbol, Inst, InstSize))
312       return std::make_pair(
313           EvalResult(("Couldn't decode instruction at '" + Symbol + "'").str()),
314           "");
315 
316     uint64_t SymbolAddr = PCtx.IsInsideLoad
317                               ? Checker.getSymbolLinkerAddr(Symbol)
318                               : Checker.getSymbolRemoteAddr(Symbol);
319     uint64_t NextPC = SymbolAddr + InstSize;
320 
321     return std::make_pair(EvalResult(NextPC), RemainingExpr);
322   }
323 
324   // Evaluate a call to stub_addr.
325   // Look up and return the address of the stub for the given
326   // (<file name>, <section name>, <symbol name>) tuple.
327   // On success, returns a pair containing the stub address, plus the expression
328   // remaining to be evaluated.
329   std::pair<EvalResult, StringRef> evalStubAddr(StringRef Expr,
330                                                 ParseContext PCtx) const {
331     if (!Expr.startswith("("))
332       return std::make_pair(unexpectedToken(Expr, Expr, "expected '('"), "");
333     StringRef RemainingExpr = Expr.substr(1).ltrim();
334 
335     // Handle file-name specially, as it may contain characters that aren't
336     // legal for symbols.
337     StringRef FileName;
338     size_t ComaIdx = RemainingExpr.find(',');
339     FileName = RemainingExpr.substr(0, ComaIdx).rtrim();
340     RemainingExpr = RemainingExpr.substr(ComaIdx).ltrim();
341 
342     if (!RemainingExpr.startswith(","))
343       return std::make_pair(
344           unexpectedToken(RemainingExpr, Expr, "expected ','"), "");
345     RemainingExpr = RemainingExpr.substr(1).ltrim();
346 
347     StringRef SectionName;
348     std::tie(SectionName, RemainingExpr) = parseSymbol(RemainingExpr);
349 
350     if (!RemainingExpr.startswith(","))
351       return std::make_pair(
352           unexpectedToken(RemainingExpr, Expr, "expected ','"), "");
353     RemainingExpr = RemainingExpr.substr(1).ltrim();
354 
355     StringRef Symbol;
356     std::tie(Symbol, RemainingExpr) = parseSymbol(RemainingExpr);
357 
358     if (!RemainingExpr.startswith(")"))
359       return std::make_pair(
360           unexpectedToken(RemainingExpr, Expr, "expected ')'"), "");
361     RemainingExpr = RemainingExpr.substr(1).ltrim();
362 
363     uint64_t StubAddr;
364     std::string ErrorMsg = "";
365     std::tie(StubAddr, ErrorMsg) = Checker.getStubAddrFor(
366         FileName, SectionName, Symbol, PCtx.IsInsideLoad);
367 
368     if (ErrorMsg != "")
369       return std::make_pair(EvalResult(ErrorMsg), "");
370 
371     return std::make_pair(EvalResult(StubAddr), RemainingExpr);
372   }
373 
374   std::pair<EvalResult, StringRef> evalSectionAddr(StringRef Expr,
375                                                    ParseContext PCtx) const {
376     if (!Expr.startswith("("))
377       return std::make_pair(unexpectedToken(Expr, Expr, "expected '('"), "");
378     StringRef RemainingExpr = Expr.substr(1).ltrim();
379 
380     // Handle file-name specially, as it may contain characters that aren't
381     // legal for symbols.
382     StringRef FileName;
383     size_t ComaIdx = RemainingExpr.find(',');
384     FileName = RemainingExpr.substr(0, ComaIdx).rtrim();
385     RemainingExpr = RemainingExpr.substr(ComaIdx).ltrim();
386 
387     if (!RemainingExpr.startswith(","))
388       return std::make_pair(
389           unexpectedToken(RemainingExpr, Expr, "expected ','"), "");
390     RemainingExpr = RemainingExpr.substr(1).ltrim();
391 
392     StringRef SectionName;
393     std::tie(SectionName, RemainingExpr) = parseSymbol(RemainingExpr);
394 
395     if (!RemainingExpr.startswith(")"))
396       return std::make_pair(
397           unexpectedToken(RemainingExpr, Expr, "expected ')'"), "");
398     RemainingExpr = RemainingExpr.substr(1).ltrim();
399 
400     uint64_t StubAddr;
401     std::string ErrorMsg = "";
402     std::tie(StubAddr, ErrorMsg) = Checker.getSectionAddr(
403         FileName, SectionName, PCtx.IsInsideLoad);
404 
405     if (ErrorMsg != "")
406       return std::make_pair(EvalResult(ErrorMsg), "");
407 
408     return std::make_pair(EvalResult(StubAddr), RemainingExpr);
409   }
410 
411   // Evaluate an identiefer expr, which may be a symbol, or a call to
412   // one of the builtin functions: get_insn_opcode or get_insn_length.
413   // Return the result, plus the expression remaining to be parsed.
414   std::pair<EvalResult, StringRef> evalIdentifierExpr(StringRef Expr,
415                                                       ParseContext PCtx) const {
416     StringRef Symbol;
417     StringRef RemainingExpr;
418     std::tie(Symbol, RemainingExpr) = parseSymbol(Expr);
419 
420     // Check for builtin function calls.
421     if (Symbol == "decode_operand")
422       return evalDecodeOperand(RemainingExpr);
423     else if (Symbol == "next_pc")
424       return evalNextPC(RemainingExpr, PCtx);
425     else if (Symbol == "stub_addr")
426       return evalStubAddr(RemainingExpr, PCtx);
427     else if (Symbol == "section_addr")
428       return evalSectionAddr(RemainingExpr, PCtx);
429 
430     if (!Checker.isSymbolValid(Symbol)) {
431       std::string ErrMsg("No known address for symbol '");
432       ErrMsg += Symbol;
433       ErrMsg += "'";
434       if (Symbol.startswith("L"))
435         ErrMsg += " (this appears to be an assembler local label - "
436                   " perhaps drop the 'L'?)";
437 
438       return std::make_pair(EvalResult(ErrMsg), "");
439     }
440 
441     // The value for the symbol depends on the context we're evaluating in:
442     // Inside a load this is the address in the linker's memory, outside a
443     // load it's the address in the target processes memory.
444     uint64_t Value = PCtx.IsInsideLoad ? Checker.getSymbolLinkerAddr(Symbol)
445                                        : Checker.getSymbolRemoteAddr(Symbol);
446 
447     // Looks like a plain symbol reference.
448     return std::make_pair(EvalResult(Value), RemainingExpr);
449   }
450 
451   // Parse a number (hexadecimal or decimal) and return a (string, string)
452   // pair representing the number and the expression remaining to be parsed.
453   std::pair<StringRef, StringRef> parseNumberString(StringRef Expr) const {
454     size_t FirstNonDigit = StringRef::npos;
455     if (Expr.startswith("0x")) {
456       FirstNonDigit = Expr.find_first_not_of("0123456789abcdefABCDEF", 2);
457       if (FirstNonDigit == StringRef::npos)
458         FirstNonDigit = Expr.size();
459     } else {
460       FirstNonDigit = Expr.find_first_not_of("0123456789");
461       if (FirstNonDigit == StringRef::npos)
462         FirstNonDigit = Expr.size();
463     }
464     return std::make_pair(Expr.substr(0, FirstNonDigit),
465                           Expr.substr(FirstNonDigit));
466   }
467 
468   // Evaluate a constant numeric expression (hexidecimal or decimal) and
469   // return a pair containing the result, and the expression remaining to be
470   // evaluated.
471   std::pair<EvalResult, StringRef> evalNumberExpr(StringRef Expr) const {
472     StringRef ValueStr;
473     StringRef RemainingExpr;
474     std::tie(ValueStr, RemainingExpr) = parseNumberString(Expr);
475 
476     if (ValueStr.empty() || !isdigit(ValueStr[0]))
477       return std::make_pair(
478           unexpectedToken(RemainingExpr, RemainingExpr, "expected number"), "");
479     uint64_t Value;
480     ValueStr.getAsInteger(0, Value);
481     return std::make_pair(EvalResult(Value), RemainingExpr);
482   }
483 
484   // Evaluate an expression of the form "(<expr>)" and return a pair
485   // containing the result of evaluating <expr>, plus the expression
486   // remaining to be parsed.
487   std::pair<EvalResult, StringRef> evalParensExpr(StringRef Expr,
488                                                   ParseContext PCtx) const {
489     assert(Expr.startswith("(") && "Not a parenthesized expression");
490     EvalResult SubExprResult;
491     StringRef RemainingExpr;
492     std::tie(SubExprResult, RemainingExpr) =
493         evalComplexExpr(evalSimpleExpr(Expr.substr(1).ltrim(), PCtx), PCtx);
494     if (SubExprResult.hasError())
495       return std::make_pair(SubExprResult, "");
496     if (!RemainingExpr.startswith(")"))
497       return std::make_pair(
498           unexpectedToken(RemainingExpr, Expr, "expected ')'"), "");
499     RemainingExpr = RemainingExpr.substr(1).ltrim();
500     return std::make_pair(SubExprResult, RemainingExpr);
501   }
502 
503   // Evaluate an expression in one of the following forms:
504   //   *{<number>}<expr>
505   // Return a pair containing the result, plus the expression remaining to be
506   // parsed.
507   std::pair<EvalResult, StringRef> evalLoadExpr(StringRef Expr) const {
508     assert(Expr.startswith("*") && "Not a load expression");
509     StringRef RemainingExpr = Expr.substr(1).ltrim();
510 
511     // Parse read size.
512     if (!RemainingExpr.startswith("{"))
513       return std::make_pair(EvalResult("Expected '{' following '*'."), "");
514     RemainingExpr = RemainingExpr.substr(1).ltrim();
515     EvalResult ReadSizeExpr;
516     std::tie(ReadSizeExpr, RemainingExpr) = evalNumberExpr(RemainingExpr);
517     if (ReadSizeExpr.hasError())
518       return std::make_pair(ReadSizeExpr, RemainingExpr);
519     uint64_t ReadSize = ReadSizeExpr.getValue();
520     if (ReadSize < 1 || ReadSize > 8)
521       return std::make_pair(EvalResult("Invalid size for dereference."), "");
522     if (!RemainingExpr.startswith("}"))
523       return std::make_pair(EvalResult("Missing '}' for dereference."), "");
524     RemainingExpr = RemainingExpr.substr(1).ltrim();
525 
526     // Evaluate the expression representing the load address.
527     ParseContext LoadCtx(true);
528     EvalResult LoadAddrExprResult;
529     std::tie(LoadAddrExprResult, RemainingExpr) =
530         evalComplexExpr(evalSimpleExpr(RemainingExpr, LoadCtx), LoadCtx);
531 
532     if (LoadAddrExprResult.hasError())
533       return std::make_pair(LoadAddrExprResult, "");
534 
535     uint64_t LoadAddr = LoadAddrExprResult.getValue();
536 
537     return std::make_pair(
538         EvalResult(Checker.readMemoryAtAddr(LoadAddr, ReadSize)),
539         RemainingExpr);
540   }
541 
542   // Evaluate a "simple" expression. This is any expression that _isn't_ an
543   // un-parenthesized binary expression.
544   //
545   // "Simple" expressions can be optionally bit-sliced. See evalSlicedExpr.
546   //
547   // Returns a pair containing the result of the evaluation, plus the
548   // expression remaining to be parsed.
549   std::pair<EvalResult, StringRef> evalSimpleExpr(StringRef Expr,
550                                                   ParseContext PCtx) const {
551     EvalResult SubExprResult;
552     StringRef RemainingExpr;
553 
554     if (Expr.empty())
555       return std::make_pair(EvalResult("Unexpected end of expression"), "");
556 
557     if (Expr[0] == '(')
558       std::tie(SubExprResult, RemainingExpr) = evalParensExpr(Expr, PCtx);
559     else if (Expr[0] == '*')
560       std::tie(SubExprResult, RemainingExpr) = evalLoadExpr(Expr);
561     else if (isalpha(Expr[0]) || Expr[0] == '_')
562       std::tie(SubExprResult, RemainingExpr) = evalIdentifierExpr(Expr, PCtx);
563     else if (isdigit(Expr[0]))
564       std::tie(SubExprResult, RemainingExpr) = evalNumberExpr(Expr);
565     else
566       return std::make_pair(
567           unexpectedToken(Expr, Expr,
568                           "expected '(', '*', identifier, or number"), "");
569 
570     if (SubExprResult.hasError())
571       return std::make_pair(SubExprResult, RemainingExpr);
572 
573     // Evaluate bit-slice if present.
574     if (RemainingExpr.startswith("["))
575       std::tie(SubExprResult, RemainingExpr) =
576           evalSliceExpr(std::make_pair(SubExprResult, RemainingExpr));
577 
578     return std::make_pair(SubExprResult, RemainingExpr);
579   }
580 
581   // Evaluate a bit-slice of an expression.
582   // A bit-slice has the form "<expr>[high:low]". The result of evaluating a
583   // slice is the bits between high and low (inclusive) in the original
584   // expression, right shifted so that the "low" bit is in position 0 in the
585   // result.
586   // Returns a pair containing the result of the slice operation, plus the
587   // expression remaining to be parsed.
588   std::pair<EvalResult, StringRef>
589   evalSliceExpr(std::pair<EvalResult, StringRef> Ctx) const {
590     EvalResult SubExprResult;
591     StringRef RemainingExpr;
592     std::tie(SubExprResult, RemainingExpr) = Ctx;
593 
594     assert(RemainingExpr.startswith("[") && "Not a slice expr.");
595     RemainingExpr = RemainingExpr.substr(1).ltrim();
596 
597     EvalResult HighBitExpr;
598     std::tie(HighBitExpr, RemainingExpr) = evalNumberExpr(RemainingExpr);
599 
600     if (HighBitExpr.hasError())
601       return std::make_pair(HighBitExpr, RemainingExpr);
602 
603     if (!RemainingExpr.startswith(":"))
604       return std::make_pair(
605           unexpectedToken(RemainingExpr, RemainingExpr, "expected ':'"), "");
606     RemainingExpr = RemainingExpr.substr(1).ltrim();
607 
608     EvalResult LowBitExpr;
609     std::tie(LowBitExpr, RemainingExpr) = evalNumberExpr(RemainingExpr);
610 
611     if (LowBitExpr.hasError())
612       return std::make_pair(LowBitExpr, RemainingExpr);
613 
614     if (!RemainingExpr.startswith("]"))
615       return std::make_pair(
616           unexpectedToken(RemainingExpr, RemainingExpr, "expected ']'"), "");
617     RemainingExpr = RemainingExpr.substr(1).ltrim();
618 
619     unsigned HighBit = HighBitExpr.getValue();
620     unsigned LowBit = LowBitExpr.getValue();
621     uint64_t Mask = ((uint64_t)1 << (HighBit - LowBit + 1)) - 1;
622     uint64_t SlicedValue = (SubExprResult.getValue() >> LowBit) & Mask;
623     return std::make_pair(EvalResult(SlicedValue), RemainingExpr);
624   }
625 
626   // Evaluate a "complex" expression.
627   // Takes an already evaluated subexpression and checks for the presence of a
628   // binary operator, computing the result of the binary operation if one is
629   // found. Used to make arithmetic expressions left-associative.
630   // Returns a pair containing the ultimate result of evaluating the
631   // expression, plus the expression remaining to be evaluated.
632   std::pair<EvalResult, StringRef>
633   evalComplexExpr(std::pair<EvalResult, StringRef> LHSAndRemaining,
634                   ParseContext PCtx) const {
635     EvalResult LHSResult;
636     StringRef RemainingExpr;
637     std::tie(LHSResult, RemainingExpr) = LHSAndRemaining;
638 
639     // If there was an error, or there's nothing left to evaluate, return the
640     // result.
641     if (LHSResult.hasError() || RemainingExpr == "")
642       return std::make_pair(LHSResult, RemainingExpr);
643 
644     // Otherwise check if this is a binary expressioan.
645     BinOpToken BinOp;
646     std::tie(BinOp, RemainingExpr) = parseBinOpToken(RemainingExpr);
647 
648     // If this isn't a recognized expression just return.
649     if (BinOp == BinOpToken::Invalid)
650       return std::make_pair(LHSResult, RemainingExpr);
651 
652     // This is a recognized bin-op. Evaluate the RHS, then evaluate the binop.
653     EvalResult RHSResult;
654     std::tie(RHSResult, RemainingExpr) = evalSimpleExpr(RemainingExpr, PCtx);
655 
656     // If there was an error evaluating the RHS, return it.
657     if (RHSResult.hasError())
658       return std::make_pair(RHSResult, RemainingExpr);
659 
660     // This is a binary expression - evaluate and try to continue as a
661     // complex expr.
662     EvalResult ThisResult(computeBinOpResult(BinOp, LHSResult, RHSResult));
663 
664     return evalComplexExpr(std::make_pair(ThisResult, RemainingExpr), PCtx);
665   }
666 
667   bool decodeInst(StringRef Symbol, MCInst &Inst, uint64_t &Size) const {
668     MCDisassembler *Dis = Checker.Disassembler;
669     StringRef SectionMem = Checker.getSubsectionStartingAt(Symbol);
670     ArrayRef<uint8_t> SectionBytes(
671         reinterpret_cast<const uint8_t *>(SectionMem.data()),
672         SectionMem.size());
673 
674     MCDisassembler::DecodeStatus S =
675         Dis->getInstruction(Inst, Size, SectionBytes, 0, nulls(), nulls());
676 
677     return (S == MCDisassembler::Success);
678   }
679 };
680 }
681 
682 RuntimeDyldCheckerImpl::RuntimeDyldCheckerImpl(RuntimeDyld &RTDyld,
683                                                MCDisassembler *Disassembler,
684                                                MCInstPrinter *InstPrinter,
685                                                raw_ostream &ErrStream)
686     : RTDyld(RTDyld), Disassembler(Disassembler), InstPrinter(InstPrinter),
687       ErrStream(ErrStream) {
688   RTDyld.Checker = this;
689 }
690 
691 bool RuntimeDyldCheckerImpl::check(StringRef CheckExpr) const {
692   CheckExpr = CheckExpr.trim();
693   DEBUG(dbgs() << "RuntimeDyldChecker: Checking '" << CheckExpr << "'...\n");
694   RuntimeDyldCheckerExprEval P(*this, ErrStream);
695   bool Result = P.evaluate(CheckExpr);
696   (void)Result;
697   DEBUG(dbgs() << "RuntimeDyldChecker: '" << CheckExpr << "' "
698                << (Result ? "passed" : "FAILED") << ".\n");
699   return Result;
700 }
701 
702 bool RuntimeDyldCheckerImpl::checkAllRulesInBuffer(StringRef RulePrefix,
703                                                    MemoryBuffer *MemBuf) const {
704   bool DidAllTestsPass = true;
705   unsigned NumRules = 0;
706 
707   const char *LineStart = MemBuf->getBufferStart();
708 
709   // Eat whitespace.
710   while (LineStart != MemBuf->getBufferEnd() && std::isspace(*LineStart))
711     ++LineStart;
712 
713   while (LineStart != MemBuf->getBufferEnd() && *LineStart != '\0') {
714     const char *LineEnd = LineStart;
715     while (LineEnd != MemBuf->getBufferEnd() && *LineEnd != '\r' &&
716            *LineEnd != '\n')
717       ++LineEnd;
718 
719     StringRef Line(LineStart, LineEnd - LineStart);
720     if (Line.startswith(RulePrefix)) {
721       DidAllTestsPass &= check(Line.substr(RulePrefix.size()));
722       ++NumRules;
723     }
724 
725     // Eat whitespace.
726     LineStart = LineEnd;
727     while (LineStart != MemBuf->getBufferEnd() && std::isspace(*LineStart))
728       ++LineStart;
729   }
730   return DidAllTestsPass && (NumRules != 0);
731 }
732 
733 bool RuntimeDyldCheckerImpl::isSymbolValid(StringRef Symbol) const {
734   return getRTDyld().getSymbolAddress(Symbol) != nullptr;
735 }
736 
737 uint64_t RuntimeDyldCheckerImpl::getSymbolLinkerAddr(StringRef Symbol) const {
738   return static_cast<uint64_t>(
739       reinterpret_cast<uintptr_t>(getRTDyld().getSymbolAddress(Symbol)));
740 }
741 
742 uint64_t RuntimeDyldCheckerImpl::getSymbolRemoteAddr(StringRef Symbol) const {
743   if (uint64_t InternalSymbolAddr = getRTDyld().getSymbolLoadAddress(Symbol))
744       return InternalSymbolAddr;
745   return getRTDyld().MemMgr->getSymbolAddress(Symbol);
746 }
747 
748 uint64_t RuntimeDyldCheckerImpl::readMemoryAtAddr(uint64_t SrcAddr,
749                                                   unsigned Size) const {
750   uintptr_t PtrSizedAddr = static_cast<uintptr_t>(SrcAddr);
751   assert(PtrSizedAddr == SrcAddr && "Linker memory pointer out-of-range.");
752   uint8_t *Src = reinterpret_cast<uint8_t*>(PtrSizedAddr);
753   return getRTDyld().readBytesUnaligned(Src, Size);
754 }
755 
756 
757 std::pair<const RuntimeDyldCheckerImpl::SectionAddressInfo*, std::string>
758 RuntimeDyldCheckerImpl::findSectionAddrInfo(StringRef FileName,
759                                             StringRef SectionName) const {
760 
761   auto SectionMapItr = Stubs.find(FileName);
762   if (SectionMapItr == Stubs.end()) {
763     std::string ErrorMsg = "File '";
764     ErrorMsg += FileName;
765     ErrorMsg += "' not found. ";
766     if (Stubs.empty())
767       ErrorMsg += "No stubs registered.";
768     else {
769       ErrorMsg += "Available files are:";
770       for (const auto& StubEntry : Stubs) {
771         ErrorMsg += " '";
772         ErrorMsg += StubEntry.first;
773         ErrorMsg += "'";
774       }
775     }
776     ErrorMsg += "\n";
777     return std::make_pair(nullptr, ErrorMsg);
778   }
779 
780   auto SectionInfoItr = SectionMapItr->second.find(SectionName);
781   if (SectionInfoItr == SectionMapItr->second.end())
782     return std::make_pair(nullptr,
783                           ("Section '" + SectionName + "' not found in file '" +
784                            FileName + "'\n").str());
785 
786   return std::make_pair(&SectionInfoItr->second, std::string(""));
787 }
788 
789 std::pair<uint64_t, std::string> RuntimeDyldCheckerImpl::getSectionAddr(
790     StringRef FileName, StringRef SectionName, bool IsInsideLoad) const {
791 
792   const SectionAddressInfo *SectionInfo = nullptr;
793   {
794     std::string ErrorMsg;
795     std::tie(SectionInfo, ErrorMsg) =
796       findSectionAddrInfo(FileName, SectionName);
797     if (ErrorMsg != "")
798       return std::make_pair(0, ErrorMsg);
799   }
800 
801   unsigned SectionID = SectionInfo->SectionID;
802   uint64_t Addr;
803   if (IsInsideLoad)
804     Addr =
805       static_cast<uint64_t>(
806         reinterpret_cast<uintptr_t>(getRTDyld().Sections[SectionID].Address));
807   else
808     Addr = getRTDyld().Sections[SectionID].LoadAddress;
809 
810   return std::make_pair(Addr, std::string(""));
811 }
812 
813 std::pair<uint64_t, std::string> RuntimeDyldCheckerImpl::getStubAddrFor(
814     StringRef FileName, StringRef SectionName, StringRef SymbolName,
815     bool IsInsideLoad) const {
816 
817   const SectionAddressInfo *SectionInfo = nullptr;
818   {
819     std::string ErrorMsg;
820     std::tie(SectionInfo, ErrorMsg) =
821       findSectionAddrInfo(FileName, SectionName);
822     if (ErrorMsg != "")
823       return std::make_pair(0, ErrorMsg);
824   }
825 
826   unsigned SectionID = SectionInfo->SectionID;
827   const StubOffsetsMap &SymbolStubs = SectionInfo->StubOffsets;
828   auto StubOffsetItr = SymbolStubs.find(SymbolName);
829   if (StubOffsetItr == SymbolStubs.end())
830     return std::make_pair(0,
831                           ("Stub for symbol '" + SymbolName + "' not found. "
832                            "If '" + SymbolName + "' is an internal symbol this "
833                            "may indicate that the stub target offset is being "
834                            "computed incorrectly.\n").str());
835 
836   uint64_t StubOffset = StubOffsetItr->second;
837 
838   uint64_t Addr;
839   if (IsInsideLoad) {
840     uintptr_t SectionBase =
841         reinterpret_cast<uintptr_t>(getRTDyld().Sections[SectionID].Address);
842     Addr = static_cast<uint64_t>(SectionBase) + StubOffset;
843   } else {
844     uint64_t SectionBase = getRTDyld().Sections[SectionID].LoadAddress;
845     Addr = SectionBase + StubOffset;
846   }
847 
848   return std::make_pair(Addr, std::string(""));
849 }
850 
851 StringRef
852 RuntimeDyldCheckerImpl::getSubsectionStartingAt(StringRef Name) const {
853   RuntimeDyldImpl::SymbolTableMap::const_iterator pos =
854       getRTDyld().GlobalSymbolTable.find(Name);
855   if (pos == getRTDyld().GlobalSymbolTable.end())
856     return StringRef();
857   RuntimeDyldImpl::SymbolLoc Loc = pos->second;
858   uint8_t *SectionAddr = getRTDyld().getSectionAddress(Loc.first);
859   return StringRef(reinterpret_cast<const char *>(SectionAddr) + Loc.second,
860                    getRTDyld().Sections[Loc.first].Size - Loc.second);
861 }
862 
863 void RuntimeDyldCheckerImpl::registerSection(
864     StringRef FilePath, unsigned SectionID) {
865   StringRef FileName = sys::path::filename(FilePath);
866   const SectionEntry &Section = getRTDyld().Sections[SectionID];
867   StringRef SectionName = Section.Name;
868 
869   Stubs[FileName][SectionName].SectionID = SectionID;
870 }
871 
872 void RuntimeDyldCheckerImpl::registerStubMap(
873     StringRef FilePath, unsigned SectionID,
874     const RuntimeDyldImpl::StubMap &RTDyldStubs) {
875   StringRef FileName = sys::path::filename(FilePath);
876   const SectionEntry &Section = getRTDyld().Sections[SectionID];
877   StringRef SectionName = Section.Name;
878 
879   Stubs[FileName][SectionName].SectionID = SectionID;
880 
881   for (auto &StubMapEntry : RTDyldStubs) {
882     std::string SymbolName = "";
883 
884     if (StubMapEntry.first.SymbolName)
885       SymbolName = StubMapEntry.first.SymbolName;
886     else {
887       // If this is a (Section, Offset) pair, do a reverse lookup in the
888       // global symbol table to find the name.
889       for (auto &GSTEntry : getRTDyld().GlobalSymbolTable) {
890         if (GSTEntry.second.first == StubMapEntry.first.SectionID &&
891             GSTEntry.second.second ==
892                 static_cast<uint64_t>(StubMapEntry.first.Offset)) {
893           SymbolName = GSTEntry.first();
894           break;
895         }
896       }
897     }
898 
899     if (SymbolName != "")
900       Stubs[FileName][SectionName].StubOffsets[SymbolName] =
901         StubMapEntry.second;
902   }
903 }
904 
905 RuntimeDyldChecker::RuntimeDyldChecker(RuntimeDyld &RTDyld,
906                                        MCDisassembler *Disassembler,
907                                        MCInstPrinter *InstPrinter,
908                                        raw_ostream &ErrStream)
909     : Impl(make_unique<RuntimeDyldCheckerImpl>(RTDyld, Disassembler,
910                                                InstPrinter, ErrStream)) {}
911 
912 RuntimeDyldChecker::~RuntimeDyldChecker() {}
913 
914 RuntimeDyld& RuntimeDyldChecker::getRTDyld() {
915   return Impl->RTDyld;
916 }
917 
918 const RuntimeDyld& RuntimeDyldChecker::getRTDyld() const {
919   return Impl->RTDyld;
920 }
921 
922 bool RuntimeDyldChecker::check(StringRef CheckExpr) const {
923   return Impl->check(CheckExpr);
924 }
925 
926 bool RuntimeDyldChecker::checkAllRulesInBuffer(StringRef RulePrefix,
927                                                MemoryBuffer *MemBuf) const {
928   return Impl->checkAllRulesInBuffer(RulePrefix, MemBuf);
929 }
930 
931 std::pair<uint64_t, std::string>
932 RuntimeDyldChecker::getSectionAddr(StringRef FileName, StringRef SectionName,
933                                    bool LinkerAddress) {
934   return Impl->getSectionAddr(FileName, SectionName, LinkerAddress);
935 }
936