lldb/source/Symbol/ArmUnwindInfo.cpp

   1 //===-- ArmUnwindInfo.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
   9 #include <vector>
  10
  11 #include "Utility/ARM_DWARF_Registers.h"
  12 #include "lldb/Core/Module.h"
  13 #include "lldb/Core/Section.h"
  14 #include "lldb/Symbol/ArmUnwindInfo.h"
  15 #include "lldb/Symbol/SymbolVendor.h"
  16 #include "lldb/Symbol/UnwindPlan.h"
  17 #include "lldb/Utility/Endian.h"
  18
  19 /*
  20  * Unwind information reader and parser for the ARM exception handling ABI
  21  *
  22  * Implemented based on:
  23  *     Exception Handling ABI for the ARM Architecture
  24  *     Document number: ARM IHI 0038A (current through ABI r2.09)
  25  *     Date of Issue: 25th January 2007, reissued 30th November 2012
  26  *     http://infocenter.arm.com/help/topic/com.arm.doc.ihi0038a/IHI0038A_ehabi.pdf
  27  */
  28
  29 using namespace lldb;
  30 using namespace lldb_private;
  31
  32 // Converts a prel31 value to lldb::addr_t with sign extension
  33 static addr_t Prel31ToAddr(uint32_t prel31) {
  34   addr_t res = prel31;
  35   if (prel31 & (1 << 30))
  36     res |= 0xffffffff80000000ULL;
  37   return res;
  38 }
  39
  40 ArmUnwindInfo::ArmExidxEntry::ArmExidxEntry(uint32_t f, lldb::addr_t a,
  41                                             uint32_t d)
  42     : file_address(f), address(a), data(d) {}
  43
  44 bool ArmUnwindInfo::ArmExidxEntry::operator<(const ArmExidxEntry &other) const {
  45   return address < other.address;
  46 }
  47
  48 ArmUnwindInfo::ArmUnwindInfo(ObjectFile &objfile, SectionSP &arm_exidx,
  49                              SectionSP &arm_extab)
  50     : m_byte_order(objfile.GetByteOrder()), m_arm_exidx_sp(arm_exidx),
  51       m_arm_extab_sp(arm_extab) {
  52   objfile.ReadSectionData(arm_exidx.get(), m_arm_exidx_data);
  53   objfile.ReadSectionData(arm_extab.get(), m_arm_extab_data);
  54
  55   addr_t exidx_base_addr = m_arm_exidx_sp->GetFileAddress();
  56
  57   offset_t offset = 0;
  58   while (m_arm_exidx_data.ValidOffset(offset)) {
  59     lldb::addr_t file_addr = exidx_base_addr + offset;
  60     lldb::addr_t addr = exidx_base_addr + (addr_t)offset +
  61                         Prel31ToAddr(m_arm_exidx_data.GetU32(&offset));
  62     uint32_t data = m_arm_exidx_data.GetU32(&offset);
  63     m_exidx_entries.emplace_back(file_addr, addr, data);
  64   }
  65
  66   // Sort the entries in the exidx section. The entries should be sorted inside
  67   // the section but some old compiler isn't sorted them.
  68   llvm::sort(m_exidx_entries.begin(), m_exidx_entries.end());
  69 }
  70
  71 ArmUnwindInfo::~ArmUnwindInfo() = default;
  72
  73 // Read a byte from the unwind instruction stream with the given offset. Custom
  74 // function is required because have to red in order of significance within
  75 // their containing word (most significant byte first) and in increasing word
  76 // address order.
  77 uint8_t ArmUnwindInfo::GetByteAtOffset(const uint32_t *data,
  78                                        uint16_t offset) const {
  79   uint32_t value = data[offset / 4];
  80   if (m_byte_order != endian::InlHostByteOrder())
  81     value = llvm::ByteSwap_32(value);
  82   return (value >> ((3 - (offset % 4)) * 8)) & 0xff;
  83 }
  84
  85 uint64_t ArmUnwindInfo::GetULEB128(const uint32_t *data, uint16_t &offset,
  86                                    uint16_t max_offset) const {
  87   uint64_t result = 0;
  88   uint8_t shift = 0;
  89   while (offset < max_offset) {
  90     uint8_t byte = GetByteAtOffset(data, offset++);
  91     result |= (uint64_t)(byte & 0x7f) << shift;
  92     if ((byte & 0x80) == 0)
  93       break;
  94     shift += 7;
  95   }
  96   return result;
  97 }
  98
  99 bool ArmUnwindInfo::GetUnwindPlan(Target &target, const Address &addr,
 100                                   UnwindPlan &unwind_plan) {
 101   const uint32_t *data = (const uint32_t *)GetExceptionHandlingTableEntry(addr);
 102   if (data == nullptr)
 103     return false; // No unwind information for the function
 104
 105   if (data[0] == 0x1)
 106     return false; // EXIDX_CANTUNWIND
 107
 108   uint16_t byte_count = 0;
 109   uint16_t byte_offset = 0;
 110   if (data[0] & 0x80000000) {
 111     switch ((data[0] >> 24) & 0x0f) {
 112     case 0:
 113       byte_count = 4;
 114       byte_offset = 1;
 115       break;
 116     case 1:
 117     case 2:
 118       byte_count = 4 * ((data[0] >> 16) & 0xff) + 4;
 119       byte_offset = 2;
 120       break;
 121     default:
 122       // Unhandled personality routine index
 123       return false;
 124     }
 125   } else {
 126     byte_count = 4 * ((data[1] >> 24) & 0xff) + 8;
 127     byte_offset = 5;
 128   }
 129
 130   uint8_t vsp_reg = dwarf_sp;
 131   int32_t vsp = 0;
 132   std::vector<std::pair<uint32_t, int32_t>>
 133       register_offsets; // register -> (offset from vsp_reg)
 134
 135   while (byte_offset < byte_count) {
 136     uint8_t byte1 = GetByteAtOffset(data, byte_offset++);
 137     if ((byte1 & 0xc0) == 0x00) {
 138       // 00xxxxxx
 139       // vsp = vsp + (xxxxxx << 2) + 4. Covers range 0x04-0x100 inclusive
 140       vsp += ((byte1 & 0x3f) << 2) + 4;
 141     } else if ((byte1 & 0xc0) == 0x40) {
 142       // 01xxxxxx
 143       // vsp = vsp – (xxxxxx << 2) - 4. Covers range 0x04-0x100 inclusive
 144       vsp -= ((byte1 & 0x3f) << 2) + 4;
 145     } else if ((byte1 & 0xf0) == 0x80) {
 146       if (byte_offset >= byte_count)
 147         return false;
 148
 149       uint8_t byte2 = GetByteAtOffset(data, byte_offset++);
 150       if (byte1 == 0x80 && byte2 == 0) {
 151         // 10000000 00000000
 152         // Refuse to unwind (for example, out of a cleanup) (see remark a)
 153         return false;
 154       } else {
 155         // 1000iiii iiiiiiii (i not all 0)
 156         // Pop up to 12 integer registers under masks {r15-r12}, {r11-r4} (see
 157         // remark b)
 158         uint16_t regs = ((byte1 & 0x0f) << 8) | byte2;
 159         for (uint8_t i = 0; i < 12; ++i) {
 160           if (regs & (1 << i)) {
 161             register_offsets.emplace_back(dwarf_r4 + i, vsp);
 162             vsp += 4;
 163           }
 164         }
 165       }
 166     } else if ((byte1 & 0xff) == 0x9d) {
 167       // 10011101
 168       // Reserved as prefix for ARM register to register moves
 169       return false;
 170     } else if ((byte1 & 0xff) == 0x9f) {
 171       // 10011111
 172       // Reserved as prefix for Intel Wireless MMX register to register moves
 173       return false;
 174     } else if ((byte1 & 0xf0) == 0x90) {
 175       // 1001nnnn (nnnn != 13,15)
 176       // Set vsp = r[nnnn]
 177       vsp_reg = dwarf_r0 + (byte1 & 0x0f);
 178     } else if ((byte1 & 0xf8) == 0xa0) {
 179       // 10100nnn
 180       // Pop r4-r[4+nnn]
 181       uint8_t n = byte1 & 0x7;
 182       for (uint8_t i = 0; i <= n; ++i) {
 183         register_offsets.emplace_back(dwarf_r4 + i, vsp);
 184         vsp += 4;
 185       }
 186     } else if ((byte1 & 0xf8) == 0xa8) {
 187       // 10101nnn
 188       // Pop r4-r[4+nnn], r14
 189       uint8_t n = byte1 & 0x7;
 190       for (uint8_t i = 0; i <= n; ++i) {
 191         register_offsets.emplace_back(dwarf_r4 + i, vsp);
 192         vsp += 4;
 193       }
 194
 195       register_offsets.emplace_back(dwarf_lr, vsp);
 196       vsp += 4;
 197     } else if ((byte1 & 0xff) == 0xb0) {
 198       // 10110000
 199       // Finish (see remark c)
 200       break;
 201     } else if ((byte1 & 0xff) == 0xb1) {
 202       if (byte_offset >= byte_count)
 203         return false;
 204
 205       uint8_t byte2 = GetByteAtOffset(data, byte_offset++);
 206       if ((byte2 & 0xff) == 0x00) {
 207         // 10110001 00000000
 208         // Spare (see remark f)
 209         return false;
 210       } else if ((byte2 & 0xf0) == 0x00) {
 211         // 10110001 0000iiii (i not all 0)
 212         // Pop integer registers under mask {r3, r2, r1, r0}
 213         for (uint8_t i = 0; i < 4; ++i) {
 214           if (byte2 & (1 << i)) {
 215             register_offsets.emplace_back(dwarf_r0 + i, vsp);
 216             vsp += 4;
 217           }
 218         }
 219       } else {
 220         // 10110001 xxxxyyyy
 221         // Spare (xxxx != 0000)
 222         return false;
 223       }
 224     } else if ((byte1 & 0xff) == 0xb2) {
 225       // 10110010 uleb128
 226       // vsp = vsp + 0x204+ (uleb128 << 2)
 227       uint64_t uleb128 = GetULEB128(data, byte_offset, byte_count);
 228       vsp += 0x204 + (uleb128 << 2);
 229     } else if ((byte1 & 0xff) == 0xb3) {
 230       // 10110011 sssscccc
 231       // Pop VFP double-precision registers D[ssss]-D[ssss+cccc] saved (as if)
 232       // by FSTMFDX (see remark d)
 233       if (byte_offset >= byte_count)
 234         return false;
 235
 236       uint8_t byte2 = GetByteAtOffset(data, byte_offset++);
 237       uint8_t s = (byte2 & 0xf0) >> 4;
 238       uint8_t c = (byte2 & 0x0f) >> 0;
 239       for (uint8_t i = 0; i <= c; ++i) {
 240         register_offsets.emplace_back(dwarf_d0 + s + i, vsp);
 241         vsp += 8;
 242       }
 243       vsp += 4;
 244     } else if ((byte1 & 0xfc) == 0xb4) {
 245       // 101101nn
 246       // Spare (was Pop FPA)
 247       return false;
 248     } else if ((byte1 & 0xf8) == 0xb8) {
 249       // 10111nnn
 250       // Pop VFP double-precision registers D[8]-D[8+nnn] saved (as if) by
 251       // FSTMFDX (see remark d)
 252       uint8_t n = byte1 & 0x07;
 253       for (uint8_t i = 0; i <= n; ++i) {
 254         register_offsets.emplace_back(dwarf_d8 + i, vsp);
 255         vsp += 8;
 256       }
 257       vsp += 4;
 258     } else if ((byte1 & 0xf8) == 0xc0) {
 259       // 11000nnn (nnn != 6,7)
 260       // Intel Wireless MMX pop wR[10]-wR[10+nnn]
 261
 262       // 11000110 sssscccc
 263       // Intel Wireless MMX pop wR[ssss]-wR[ssss+cccc] (see remark e)
 264
 265       // 11000111 00000000
 266       // Spare
 267
 268       // 11000111 0000iiii
 269       // Intel Wireless MMX pop wCGR registers under mask {wCGR3,2,1,0}
 270
 271       // 11000111 xxxxyyyy
 272       // Spare (xxxx != 0000)
 273
 274       return false;
 275     } else if ((byte1 & 0xff) == 0xc8) {
 276       // 11001000 sssscccc
 277       // Pop VFP double precision registers D[16+ssss]-D[16+ssss+cccc] saved
 278       // (as if) by FSTMFDD (see remarks d,e)
 279       if (byte_offset >= byte_count)
 280         return false;
 281
 282       uint8_t byte2 = GetByteAtOffset(data, byte_offset++);
 283       uint8_t s = (byte2 & 0xf0) >> 4;
 284       uint8_t c = (byte2 & 0x0f) >> 0;
 285       for (uint8_t i = 0; i <= c; ++i) {
 286         register_offsets.emplace_back(dwarf_d16 + s + i, vsp);
 287         vsp += 8;
 288       }
 289     } else if ((byte1 & 0xff) == 0xc9) {
 290       // 11001001 sssscccc
 291       // Pop VFP double precision registers D[ssss]-D[ssss+cccc] saved (as if)
 292       // by FSTMFDD (see remark d)
 293       if (byte_offset >= byte_count)
 294         return false;
 295
 296       uint8_t byte2 = GetByteAtOffset(data, byte_offset++);
 297       uint8_t s = (byte2 & 0xf0) >> 4;
 298       uint8_t c = (byte2 & 0x0f) >> 0;
 299       for (uint8_t i = 0; i <= c; ++i) {
 300         register_offsets.emplace_back(dwarf_d0 + s + i, vsp);
 301         vsp += 8;
 302       }
 303     } else if ((byte1 & 0xf8) == 0xc8) {
 304       // 11001yyy
 305       // Spare (yyy != 000, 001)
 306       return false;
 307     } else if ((byte1 & 0xf8) == 0xd0) {
 308       // 11010nnn
 309       // Pop VFP double-precision registers D[8]-D[8+nnn] saved (as if) by
 310       // FSTMFDD (see remark d)
 311       uint8_t n = byte1 & 0x07;
 312       for (uint8_t i = 0; i <= n; ++i) {
 313         register_offsets.emplace_back(dwarf_d8 + i, vsp);
 314         vsp += 8;
 315       }
 316     } else if ((byte1 & 0xc0) == 0xc0) {
 317       // 11xxxyyy Spare (xxx != 000, 001, 010)
 318       return false;
 319     } else {
 320       return false;
 321     }
 322   }
 323
 324   UnwindPlan::RowSP row = std::make_shared<UnwindPlan::Row>();
 325   row->SetOffset(0);
 326   row->GetCFAValue().SetIsRegisterPlusOffset(vsp_reg, vsp);
 327
 328   bool have_location_for_pc = false;
 329   for (const auto &offset : register_offsets) {
 330     have_location_for_pc |= offset.first == dwarf_pc;
 331     row->SetRegisterLocationToAtCFAPlusOffset(offset.first, offset.second - vsp,
 332                                               true);
 333   }
 334
 335   if (!have_location_for_pc) {
 336     UnwindPlan::Row::RegisterLocation lr_location;
 337     if (row->GetRegisterInfo(dwarf_lr, lr_location))
 338       row->SetRegisterInfo(dwarf_pc, lr_location);
 339     else
 340       row->SetRegisterLocationToRegister(dwarf_pc, dwarf_lr, false);
 341   }
 342
 343   unwind_plan.AppendRow(row);
 344   unwind_plan.SetSourceName("ARM.exidx unwind info");
 345   unwind_plan.SetSourcedFromCompiler(eLazyBoolYes);
 346   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
 347   unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
 348   unwind_plan.SetRegisterKind(eRegisterKindDWARF);
 349
 350   return true;
 351 }
 352
 353 const uint8_t *
 354 ArmUnwindInfo::GetExceptionHandlingTableEntry(const Address &addr) {
 355   auto it = std::upper_bound(m_exidx_entries.begin(), m_exidx_entries.end(),
 356                              ArmExidxEntry{0, addr.GetFileAddress(), 0});
 357   if (it == m_exidx_entries.begin())
 358     return nullptr;
 359   --it;
 360
 361   if (it->data == 0x1)
 362     return nullptr; // EXIDX_CANTUNWIND
 363
 364   if (it->data & 0x80000000)
 365     return (const uint8_t *)&it->data;
 366
 367   addr_t data_file_addr = it->file_address + 4 + Prel31ToAddr(it->data);
 368   return m_arm_extab_data.GetDataStart() +
 369          (data_file_addr - m_arm_extab_sp->GetFileAddress());
 370 }