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ArchitectureMips.cpp
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1 //===-- ArchitectureMips.cpp ----------------------------------------------===//
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 
10 #include "lldb/Core/Address.h"
11 #include "lldb/Core/Disassembler.h"
12 #include "lldb/Core/Module.h"
14 #include "lldb/Symbol/Function.h"
17 #include "lldb/Target/Target.h"
18 #include "lldb/Utility/ArchSpec.h"
19 #include "lldb/Utility/Log.h"
20 
21 using namespace lldb_private;
22 using namespace lldb;
23 
25 
26 ConstString ArchitectureMips::GetPluginNameStatic() {
27  return ConstString("mips");
28 }
29 
31  PluginManager::RegisterPlugin(GetPluginNameStatic(),
32  "Mips-specific algorithms",
34 }
35 
38 }
39 
40 std::unique_ptr<Architecture> ArchitectureMips::Create(const ArchSpec &arch) {
41  return arch.IsMIPS() ?
42  std::unique_ptr<Architecture>(new ArchitectureMips(arch)) : nullptr;
43 }
44 
45 ConstString ArchitectureMips::GetPluginName() { return GetPluginNameStatic(); }
47 
49  AddressClass addr_class) const {
50  bool is_alternate_isa = false;
51 
52  switch (addr_class) {
55  return LLDB_INVALID_ADDRESS;
57  is_alternate_isa = true;
58  break;
59  default: break;
60  }
61 
62  if ((code_addr & 2ull) || is_alternate_isa)
63  return code_addr | 1u;
64  return code_addr;
65 }
66 
68  AddressClass addr_class) const {
69  switch (addr_class) {
72  return LLDB_INVALID_ADDRESS;
73  default: break;
74  }
75  return opcode_addr & ~(1ull);
76 }
77 
79  Target &target) const {
80 
82 
83  Address resolved_addr;
84 
85  SectionLoadList &section_load_list = target.GetSectionLoadList();
86  if (section_load_list.IsEmpty())
87  // No sections are loaded, so we must assume we are not running yet and
88  // need to operate only on file address.
89  target.ResolveFileAddress(addr, resolved_addr);
90  else
91  target.ResolveLoadAddress(addr, resolved_addr);
92 
93  addr_t current_offset = 0;
94 
95  // Get the function boundaries to make sure we don't scan back before the
96  // beginning of the current function.
97  ModuleSP temp_addr_module_sp(resolved_addr.GetModule());
98  if (temp_addr_module_sp) {
99  SymbolContext sc;
100  SymbolContextItem resolve_scope =
101  eSymbolContextFunction | eSymbolContextSymbol;
102  temp_addr_module_sp->ResolveSymbolContextForAddress(resolved_addr,
103  resolve_scope, sc);
104  Address sym_addr;
105  if (sc.function)
106  sym_addr = sc.function->GetAddressRange().GetBaseAddress();
107  else if (sc.symbol)
108  sym_addr = sc.symbol->GetAddress();
109 
110  addr_t function_start = sym_addr.GetLoadAddress(&target);
111  if (function_start == LLDB_INVALID_ADDRESS)
112  function_start = sym_addr.GetFileAddress();
113 
114  if (function_start)
115  current_offset = addr - function_start;
116  }
117 
118  // If breakpoint address is start of function then we dont have to do
119  // anything.
120  if (current_offset == 0)
121  return addr;
122 
123  auto insn = GetInstructionAtAddress(target, current_offset, addr);
124 
125  if (nullptr == insn || !insn->HasDelaySlot())
126  return addr;
127 
128  // Adjust the breakable address
129  uint64_t breakable_addr = addr - insn->GetOpcode().GetByteSize();
130  LLDB_LOGF(log,
131  "Target::%s Breakpoint at 0x%8.8" PRIx64
132  " is adjusted to 0x%8.8" PRIx64 " due to delay slot\n",
133  __FUNCTION__, addr, breakable_addr);
134 
135  return breakable_addr;
136 }
137 
139  Target &target, const Address &resolved_addr, addr_t symbol_offset) const {
140 
141  auto loop_count = symbol_offset / 2;
142 
143  uint32_t arch_flags = m_arch.GetFlags();
144  bool IsMips16 = arch_flags & ArchSpec::eMIPSAse_mips16;
145  bool IsMicromips = arch_flags & ArchSpec::eMIPSAse_micromips;
146 
147  if (loop_count > 3) {
148  // Scan previous 6 bytes
149  if (IsMips16 | IsMicromips)
150  loop_count = 3;
151  // For mips-only, instructions are always 4 bytes, so scan previous 4
152  // bytes only.
153  else
154  loop_count = 2;
155  }
156 
157  // Create Disassembler Instance
158  lldb::DisassemblerSP disasm_sp(
159  Disassembler::FindPlugin(m_arch, nullptr, nullptr));
160 
161  InstructionList instruction_list;
162  InstructionSP prev_insn;
163  bool prefer_file_cache = true; // Read from file
164  uint32_t inst_to_choose = 0;
165 
166  Address addr = resolved_addr;
167 
168  for (uint32_t i = 1; i <= loop_count; i++) {
169  // Adjust the address to read from.
170  addr.Slide(-2);
171  uint32_t insn_size = 0;
172 
173  disasm_sp->ParseInstructions(target, addr,
174  {Disassembler::Limit::Bytes, i * 2}, nullptr,
175  prefer_file_cache);
176 
177  uint32_t num_insns = disasm_sp->GetInstructionList().GetSize();
178  if (num_insns) {
179  prev_insn = disasm_sp->GetInstructionList().GetInstructionAtIndex(0);
180  insn_size = prev_insn->GetOpcode().GetByteSize();
181  if (i == 1 && insn_size == 2) {
182  // This looks like a valid 2-byte instruction (but it could be a part
183  // of upper 4 byte instruction).
184  instruction_list.Append(prev_insn);
185  inst_to_choose = 1;
186  }
187  else if (i == 2) {
188  // Here we may get one 4-byte instruction or two 2-byte instructions.
189  if (num_insns == 2) {
190  // Looks like there are two 2-byte instructions above our
191  // breakpoint target address. Now the upper 2-byte instruction is
192  // either a valid 2-byte instruction or could be a part of it's
193  // upper 4-byte instruction. In both cases we don't care because in
194  // this case lower 2-byte instruction is definitely a valid
195  // instruction and whatever i=1 iteration has found out is true.
196  inst_to_choose = 1;
197  break;
198  }
199  else if (insn_size == 4) {
200  // This instruction claims its a valid 4-byte instruction. But it
201  // could be a part of it's upper 4-byte instruction. Lets try
202  // scanning upper 2 bytes to verify this.
203  instruction_list.Append(prev_insn);
204  inst_to_choose = 2;
205  }
206  }
207  else if (i == 3) {
208  if (insn_size == 4)
209  // FIXME: We reached here that means instruction at [target - 4] has
210  // already claimed to be a 4-byte instruction, and now instruction
211  // at [target - 6] is also claiming that it's a 4-byte instruction.
212  // This can not be true. In this case we can not decide the valid
213  // previous instruction so we let lldb set the breakpoint at the
214  // address given by user.
215  inst_to_choose = 0;
216  else
217  // This is straight-forward
218  inst_to_choose = 2;
219  break;
220  }
221  }
222  else {
223  // Decode failed, bytes do not form a valid instruction. So whatever
224  // previous iteration has found out is true.
225  if (i > 1) {
226  inst_to_choose = i - 1;
227  break;
228  }
229  }
230  }
231 
232  // Check if we are able to find any valid instruction.
233  if (inst_to_choose) {
234  if (inst_to_choose > instruction_list.GetSize())
235  inst_to_choose--;
236  return instruction_list.GetInstructionAtIndex(inst_to_choose - 1).get();
237  }
238 
239  return nullptr;
240 }
A class that represents a running process on the host machine.
Defines a symbol context baton that can be handed other debug core functions.
Definition: SymbolContext.h:33
lldb::addr_t GetLoadAddress(Target *target) const
Get the load address.
Definition: Address.cpp:310
lldb::addr_t GetOpcodeLoadAddress(lldb::addr_t load_addr, AddressClass addr_class) const override
Get load_addr as an opcode for this target.
lldb::addr_t GetBreakableLoadAddress(lldb::addr_t addr, Target &) const override
static bool RegisterPlugin(ConstString name, const char *description, ABICreateInstance create_callback)
An architecture specification class.
Definition: ArchSpec.h:33
lldb::addr_t GetFileAddress() const
Get the file address.
Definition: Address.cpp:290
ConstString GetPluginName() override
bool ResolveFileAddress(lldb::addr_t load_addr, Address &so_addr)
Definition: Target.cpp:2730
Address GetAddress() const
Definition: Symbol.h:73
Symbol * symbol
The Symbol for a given query.
static lldb::DisassemblerSP FindPlugin(const ArchSpec &arch, const char *flavor, const char *plugin_name)
Function * function
The Function for a given query.
bool Slide(int64_t offset)
Definition: Address.h:436
#define LLDB_INVALID_ADDRESS
Invalid value definitions.
Definition: lldb-defines.h:85
#define LLDB_PLUGIN_DEFINE(PluginName)
Definition: PluginManager.h:31
Log * GetLogIfAllCategoriesSet(uint32_t mask)
Definition: Logging.cpp:58
Instruction * GetInstructionAtAddress(Target &target, const Address &resolved_addr, lldb::addr_t symbol_offset) const
SectionLoadList & GetSectionLoadList()
Definition: Target.h:1012
#define LIBLLDB_LOG_BREAKPOINTS
Definition: Logging.h:19
A section + offset based address class.
Definition: Address.h:59
void Append(lldb::InstructionSP &inst_sp)
bool IsMIPS() const
if MIPS architecture return true.
Definition: ArchSpec.cpp:592
uint32_t GetPluginVersion() override
static std::unique_ptr< Architecture > Create(const ArchSpec &arch)
#define LLDB_LOGF(log,...)
Definition: Log.h:249
lldb::InstructionSP GetInstructionAtIndex(size_t idx) const
uint64_t addr_t
Definition: lldb-types.h:83
static bool UnregisterPlugin(ABICreateInstance create_callback)
A uniqued constant string class.
Definition: ConstString.h:40
lldb::ModuleSP GetModule() const
Get accessor for the module for this address.
Definition: Address.cpp:282
Definition: SBAddress.h:15
Address & GetBaseAddress()
Get accessor for the base address of the range.
Definition: AddressRange.h:210
bool ResolveLoadAddress(lldb::addr_t load_addr, Address &so_addr, uint32_t stop_id=SectionLoadHistory::eStopIDNow)
Definition: Target.cpp:2725
lldb::addr_t GetCallableLoadAddress(lldb::addr_t load_addr, AddressClass addr_class) const override
Get load_addr as a callable code load address for this target.
const AddressRange & GetAddressRange()
Definition: Function.h:438