1//===- Disassembler.cpp - Disassembler for hex strings --------------------===//
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// This class implements the disassembler of strings of bytes written in
10// hexadecimal, from standard input or from a file.
11//
12//===----------------------------------------------------------------------===//
13
14#include "Disassembler.h"
15#include "llvm/ADT/Triple.h"
16#include "llvm/MC/MCAsmInfo.h"
17#include "llvm/MC/MCContext.h"
18#include "llvm/MC/MCDisassembler/MCDisassembler.h"
19#include "llvm/MC/MCInst.h"
20#include "llvm/MC/MCRegisterInfo.h"
21#include "llvm/MC/MCStreamer.h"
22#include "llvm/MC/MCSubtargetInfo.h"
23#include "llvm/MC/TargetRegistry.h"
24#include "llvm/Support/MemoryBuffer.h"
25#include "llvm/Support/SourceMgr.h"
26#include "llvm/Support/raw_ostream.h"
27
28using namespace llvm;
29
30typedef std::pair<std::vector<unsigned char>, std::vector<const char *>>
31    ByteArrayTy;
32
33static bool PrintInsts(const MCDisassembler &DisAsm, const ByteArrayTy &Bytes,
34                       SourceMgr &SM, raw_ostream &Out, MCStreamer &Streamer,
35                       bool InAtomicBlock, const MCSubtargetInfo &STI) {
36  ArrayRef<uint8_t> Data(Bytes.first.data(), Bytes.first.size());
37
38  // Disassemble it to strings.
39  uint64_t Size;
40  uint64_t Index;
41
42  for (Index = 0; Index < Bytes.first.size(); Index += Size) {
43    MCInst Inst;
44
45    MCDisassembler::DecodeStatus S;
46    S = DisAsm.getInstruction(Inst, Size, Data.slice(Index), Index, nulls());
47    switch (S) {
48    case MCDisassembler::Fail:
49      SM.PrintMessage(SMLoc::getFromPointer(Bytes.second[Index]),
50                      SourceMgr::DK_Warning, "invalid instruction encoding");
51      // Don't try to resynchronise the stream in a block
52      if (InAtomicBlock)
53        return true;
54
55      if (Size == 0)
56        Size = 1;  // skip illegible bytes
57
58      break;
59
60    case MCDisassembler::SoftFail:
61      SM.PrintMessage(SMLoc::getFromPointer(Bytes.second[Index]),
62                      SourceMgr::DK_Warning,
63                      "potentially undefined instruction encoding");
64      [[fallthrough]];
65
66    case MCDisassembler::Success:
67      Streamer.emitInstruction(Inst, STI);
68      break;
69    }
70  }
71
72  return false;
73}
74
75static bool SkipToToken(StringRef &Str) {
76  for (;;) {
77    if (Str.empty())
78      return false;
79
80    // Strip horizontal whitespace and commas.
81    if (size_t Pos = Str.find_first_not_of(" \t\r\n,")) {
82      Str = Str.substr(Pos);
83      continue;
84    }
85
86    // If this is the start of a comment, remove the rest of the line.
87    if (Str[0] == '#') {
88      Str = Str.substr(Str.find_first_of('\n'));
89      continue;
90    }
91    return true;
92  }
93}
94
95static bool ByteArrayFromString(ByteArrayTy &ByteArray, StringRef &Str,
96                                SourceMgr &SM) {
97  while (SkipToToken(Str)) {
98    // Handled by higher level
99    if (Str[0] == '[' || Str[0] == ']')
100      return false;
101
102    // Get the current token.
103    size_t Next = Str.find_first_of(" \t\n\r,#[]");
104    StringRef Value = Str.substr(0, Next);
105
106    // Convert to a byte and add to the byte vector.
107    unsigned ByteVal;
108    if (Value.getAsInteger(0, ByteVal) || ByteVal > 255) {
109      // If we have an error, print it and skip to the end of line.
110      SM.PrintMessage(SMLoc::getFromPointer(Value.data()), SourceMgr::DK_Error,
111                      "invalid input token");
112      Str = Str.substr(Str.find('\n'));
113      ByteArray.first.clear();
114      ByteArray.second.clear();
115      continue;
116    }
117
118    ByteArray.first.push_back(ByteVal);
119    ByteArray.second.push_back(Value.data());
120    Str = Str.substr(Next);
121  }
122
123  return false;
124}
125
126int Disassembler::disassemble(const Target &T, const std::string &TripleName,
127                              MCSubtargetInfo &STI, MCStreamer &Streamer,
128                              MemoryBuffer &Buffer, SourceMgr &SM,
129                              raw_ostream &Out) {
130  std::unique_ptr<const MCRegisterInfo> MRI(T.createMCRegInfo(TripleName));
131  if (!MRI) {
132    errs() << "error: no register info for target " << TripleName << "\n";
133    return -1;
134  }
135
136  MCTargetOptions MCOptions;
137  std::unique_ptr<const MCAsmInfo> MAI(
138      T.createMCAsmInfo(*MRI, TripleName, MCOptions));
139  if (!MAI) {
140    errs() << "error: no assembly info for target " << TripleName << "\n";
141    return -1;
142  }
143
144  // Set up the MCContext for creating symbols and MCExpr's.
145  MCContext Ctx(Triple(TripleName), MAI.get(), MRI.get(), &STI);
146
147  std::unique_ptr<const MCDisassembler> DisAsm(
148      T.createMCDisassembler(STI, Ctx));
149  if (!DisAsm) {
150    errs() << "error: no disassembler for target " << TripleName << "\n";
151    return -1;
152  }
153
154  // Set up initial section manually here
155  Streamer.initSections(false, STI);
156
157  bool ErrorOccurred = false;
158
159  // Convert the input to a vector for disassembly.
160  ByteArrayTy ByteArray;
161  StringRef Str = Buffer.getBuffer();
162  bool InAtomicBlock = false;
163
164  while (SkipToToken(Str)) {
165    ByteArray.first.clear();
166    ByteArray.second.clear();
167
168    if (Str[0] == '[') {
169      if (InAtomicBlock) {
170        SM.PrintMessage(SMLoc::getFromPointer(Str.data()), SourceMgr::DK_Error,
171                        "nested atomic blocks make no sense");
172        ErrorOccurred = true;
173      }
174      InAtomicBlock = true;
175      Str = Str.drop_front();
176      continue;
177    } else if (Str[0] == ']') {
178      if (!InAtomicBlock) {
179        SM.PrintMessage(SMLoc::getFromPointer(Str.data()), SourceMgr::DK_Error,
180                        "attempt to close atomic block without opening");
181        ErrorOccurred = true;
182      }
183      InAtomicBlock = false;
184      Str = Str.drop_front();
185      continue;
186    }
187
188    // It's a real token, get the bytes and emit them
189    ErrorOccurred |= ByteArrayFromString(ByteArray, Str, SM);
190
191    if (!ByteArray.first.empty())
192      ErrorOccurred |=
193          PrintInsts(*DisAsm, ByteArray, SM, Out, Streamer, InAtomicBlock, STI);
194  }
195
196  if (InAtomicBlock) {
197    SM.PrintMessage(SMLoc::getFromPointer(Str.data()), SourceMgr::DK_Error,
198                    "unclosed atomic block");
199    ErrorOccurred = true;
200  }
201
202  return ErrorOccurred;
203}
204