1//===-- llvm/Support/WinARMEH.h - Windows on ARM EH Constants ---*- 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#ifndef LLVM_SUPPORT_WINARMEH_H 11#define LLVM_SUPPORT_WINARMEH_H 12 13#include "llvm/ADT/ArrayRef.h" 14#include "llvm/Support/Endian.h" 15 16namespace llvm { 17namespace ARM { 18namespace WinEH { 19enum class RuntimeFunctionFlag { 20 RFF_Unpacked, /// unpacked entry 21 RFF_Packed, /// packed entry 22 RFF_PackedFragment, /// packed entry representing a fragment 23 RFF_Reserved, /// reserved 24}; 25 26enum class ReturnType { 27 RT_POP, /// return via pop {pc} (L flag must be set) 28 RT_B, /// 16-bit branch 29 RT_BW, /// 32-bit branch 30 RT_NoEpilogue, /// no epilogue (fragment) 31}; 32 33/// RuntimeFunction - An entry in the table of procedure data (.pdata) 34/// 35/// 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 36/// 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 37/// +---------------------------------------------------------------+ 38/// | Function Start RVA | 39/// +-------------------+-+-+-+-----+-+---+---------------------+---+ 40/// | Stack Adjust |C|L|R| Reg |H|Ret| Function Length |Flg| 41/// +-------------------+-+-+-+-----+-+---+---------------------+---+ 42/// 43/// Flag : 2-bit field with the following meanings: 44/// - 00 = packed unwind data not used; reamining bits point to .xdata record 45/// - 01 = packed unwind data 46/// - 10 = packed unwind data, function assumed to have no prologue; useful 47/// for function fragments that are discontiguous with the start of the 48/// function 49/// - 11 = reserved 50/// Function Length : 11-bit field providing the length of the entire function 51/// in bytes, divided by 2; if the function is greater than 52/// 4KB, a full .xdata record must be used instead 53/// Ret : 2-bit field indicating how the function returns 54/// - 00 = return via pop {pc} (the L bit must be set) 55/// - 01 = return via 16-bit branch 56/// - 10 = return via 32-bit branch 57/// - 11 = no epilogue; useful for function fragments that may only contain a 58/// prologue but the epilogue is elsewhere 59/// H : 1-bit flag indicating whether the function "homes" the integer parameter 60/// registers (r0-r3), allocating 16-bytes on the stack 61/// Reg : 3-bit field indicating the index of the last saved non-volatile 62/// register. If the R bit is set to 0, then only integer registers are 63/// saved (r4-rN, where N is 4 + Reg). If the R bit is set to 1, then 64/// only floating-point registers are being saved (d8-dN, where N is 65/// 8 + Reg). The special case of the R bit being set to 1 and Reg equal 66/// to 7 indicates that no registers are saved. 67/// R : 1-bit flag indicating whether the non-volatile registers are integer or 68/// floating-point. 0 indicates integer, 1 indicates floating-point. The 69/// special case of the R-flag being set and Reg being set to 7 indicates 70/// that no non-volatile registers are saved. 71/// L : 1-bit flag indicating whether the function saves/restores the link 72/// register (LR) 73/// C : 1-bit flag indicating whether the function includes extra instructions 74/// to setup a frame chain for fast walking. If this flag is set, r11 is 75/// implicitly added to the list of saved non-volatile integer registers. 76/// Stack Adjust : 10-bit field indicating the number of bytes of stack that are 77/// allocated for this function. Only values between 0x000 and 78/// 0x3f3 can be directly encoded. If the value is 0x3f4 or 79/// greater, then the low 4 bits have special meaning as follows: 80/// - Bit 0-1 81/// indicate the number of words' of adjustment (1-4), minus 1 82/// - Bit 2 83/// indicates if the prologue combined adjustment into push 84/// - Bit 3 85/// indicates if the epilogue combined adjustment into pop 86/// 87/// RESTRICTIONS: 88/// - IF C is SET: 89/// + L flag must be set since frame chaining requires r11 and lr 90/// + r11 must NOT be included in the set of registers described by Reg 91/// - IF Ret is 0: 92/// + L flag must be set 93 94// NOTE: RuntimeFunction is meant to be a simple class that provides raw access 95// to all fields in the structure. The accessor methods reflect the names of 96// the bitfields that they correspond to. Although some obvious simplifications 97// are possible via merging of methods, it would prevent the use of this class 98// to fully inspect the contents of the data structure which is particularly 99// useful for scenarios such as llvm-readobj to aid in testing. 100 101class RuntimeFunction { 102public: 103 const support::ulittle32_t BeginAddress; 104 const support::ulittle32_t UnwindData; 105 106 RuntimeFunction(const support::ulittle32_t *Data) 107 : BeginAddress(Data[0]), UnwindData(Data[1]) {} 108 109 RuntimeFunction(const support::ulittle32_t BeginAddress, 110 const support::ulittle32_t UnwindData) 111 : BeginAddress(BeginAddress), UnwindData(UnwindData) {} 112 113 RuntimeFunctionFlag Flag() const { 114 return RuntimeFunctionFlag(UnwindData & 0x3); 115 } 116 117 uint32_t ExceptionInformationRVA() const { 118 assert(Flag() == RuntimeFunctionFlag::RFF_Unpacked && 119 "unpacked form required for this operation"); 120 return (UnwindData & ~0x3); 121 } 122 123 uint32_t PackedUnwindData() const { 124 assert((Flag() == RuntimeFunctionFlag::RFF_Packed || 125 Flag() == RuntimeFunctionFlag::RFF_PackedFragment) && 126 "packed form required for this operation"); 127 return (UnwindData & ~0x3); 128 } 129 uint32_t FunctionLength() const { 130 assert((Flag() == RuntimeFunctionFlag::RFF_Packed || 131 Flag() == RuntimeFunctionFlag::RFF_PackedFragment) && 132 "packed form required for this operation"); 133 return (((UnwindData & 0x00001ffc) >> 2) << 1); 134 } 135 ReturnType Ret() const { 136 assert((Flag() == RuntimeFunctionFlag::RFF_Packed || 137 Flag() == RuntimeFunctionFlag::RFF_PackedFragment) && 138 "packed form required for this operation"); 139 assert(((UnwindData & 0x00006000) || L()) && "L must be set to 1"); 140 return ReturnType((UnwindData & 0x00006000) >> 13); 141 } 142 bool H() const { 143 assert((Flag() == RuntimeFunctionFlag::RFF_Packed || 144 Flag() == RuntimeFunctionFlag::RFF_PackedFragment) && 145 "packed form required for this operation"); 146 return ((UnwindData & 0x00008000) >> 15); 147 } 148 uint8_t Reg() const { 149 assert((Flag() == RuntimeFunctionFlag::RFF_Packed || 150 Flag() == RuntimeFunctionFlag::RFF_PackedFragment) && 151 "packed form required for this operation"); 152 return ((UnwindData & 0x00070000) >> 16); 153 } 154 bool R() const { 155 assert((Flag() == RuntimeFunctionFlag::RFF_Packed || 156 Flag() == RuntimeFunctionFlag::RFF_PackedFragment) && 157 "packed form required for this operation"); 158 return ((UnwindData & 0x00080000) >> 19); 159 } 160 bool L() const { 161 assert((Flag() == RuntimeFunctionFlag::RFF_Packed || 162 Flag() == RuntimeFunctionFlag::RFF_PackedFragment) && 163 "packed form required for this operation"); 164 return ((UnwindData & 0x00100000) >> 20); 165 } 166 bool C() const { 167 assert((Flag() == RuntimeFunctionFlag::RFF_Packed || 168 Flag() == RuntimeFunctionFlag::RFF_PackedFragment) && 169 "packed form required for this operation"); 170 assert(((~UnwindData & 0x00200000) || L()) && 171 "L flag must be set, chaining requires r11 and LR"); 172 assert(((~UnwindData & 0x00200000) || (Reg() < 7) || R()) && 173 "r11 must not be included in Reg; C implies r11"); 174 return ((UnwindData & 0x00200000) >> 21); 175 } 176 uint16_t StackAdjust() const { 177 assert((Flag() == RuntimeFunctionFlag::RFF_Packed || 178 Flag() == RuntimeFunctionFlag::RFF_PackedFragment) && 179 "packed form required for this operation"); 180 return ((UnwindData & 0xffc00000) >> 22); 181 } 182}; 183 184/// PrologueFolding - pseudo-flag derived from Stack Adjust indicating that the 185/// prologue has stack adjustment combined into the push 186inline bool PrologueFolding(const RuntimeFunction &RF) { 187 return RF.StackAdjust() >= 0x3f4 && (RF.StackAdjust() & 0x4); 188} 189/// Epilogue - pseudo-flag derived from Stack Adjust indicating that the 190/// epilogue has stack adjustment combined into the pop 191inline bool EpilogueFolding(const RuntimeFunction &RF) { 192 return RF.StackAdjust() >= 0x3f4 && (RF.StackAdjust() & 0x8); 193} 194/// StackAdjustment - calculated stack adjustment in words. The stack 195/// adjustment should be determined via this function to account for the special 196/// handling the special encoding when the value is >= 0x3f4. 197inline uint16_t StackAdjustment(const RuntimeFunction &RF) { 198 uint16_t Adjustment = RF.StackAdjust(); 199 if (Adjustment >= 0x3f4) 200 return (Adjustment & 0x3) ? ((Adjustment & 0x3) << 2) - 1 : 0; 201 return Adjustment; 202} 203 204/// SavedRegisterMask - Utility function to calculate the set of saved general 205/// purpose (r0-r15) and VFP (d0-d31) registers. 206std::pair<uint16_t, uint32_t> SavedRegisterMask(const RuntimeFunction &RF); 207 208/// ExceptionDataRecord - An entry in the table of exception data (.xdata) 209/// 210/// 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 211/// 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 212/// +-------+---------+-+-+-+---+-----------------------------------+ 213/// | C Wrd | Epi Cnt |F|E|X|Ver| Function Length | 214/// +-------+--------+'-'-'-'---'---+-------------------------------+ 215/// | Reserved |Ex. Code Words| (Extended Epilogue Count) | 216/// +-------+--------+--------------+-------------------------------+ 217/// 218/// Function Length : 18-bit field indicating the total length of the function 219/// in bytes divided by 2. If a function is larger than 220/// 512KB, then multiple pdata and xdata records must be used. 221/// Vers : 2-bit field describing the version of the remaining structure. Only 222/// version 0 is currently defined (values 1-3 are not permitted). 223/// X : 1-bit field indicating the presence of exception data 224/// E : 1-bit field indicating that the single epilogue is packed into the 225/// header 226/// F : 1-bit field indicating that the record describes a function fragment 227/// (implies that no prologue is present, and prologue processing should be 228/// skipped) 229/// Epilogue Count : 5-bit field that differs in meaning based on the E field. 230/// 231/// If E is set, then this field specifies the index of the 232/// first unwind code describing the (only) epilogue. 233/// 234/// Otherwise, this field indicates the number of exception 235/// scopes. If more than 31 scopes exist, then this field and 236/// the Code Words field must both be set to 0 to indicate that 237/// an extension word is required. 238/// Code Words : 4-bit field that species the number of 32-bit words needed to 239/// contain all the unwind codes. If more than 15 words (63 code 240/// bytes) are required, then this field and the Epilogue Count 241/// field must both be set to 0 to indicate that an extension word 242/// is required. 243/// Extended Epilogue Count, Extended Code Words : 244/// Valid only if Epilog Count and Code Words are both 245/// set to 0. Provides an 8-bit extended code word 246/// count and 16-bits for epilogue count 247/// 248/// 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 249/// 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 250/// +----------------+------+---+---+-------------------------------+ 251/// | Ep Start Idx | Cond |Res| Epilogue Start Offset | 252/// +----------------+------+---+-----------------------------------+ 253/// 254/// If the E bit is unset in the header, the header is followed by a series of 255/// epilogue scopes, which are sorted by their offset. 256/// 257/// Epilogue Start Offset: 18-bit field encoding the offset of epilogue relative 258/// to the start of the function in bytes divided by two 259/// Res : 2-bit field reserved for future expansion (must be set to 0) 260/// Condition : 4-bit field providing the condition under which the epilogue is 261/// executed. Unconditional epilogues should set this field to 0xe. 262/// Epilogues must be entirely conditional or unconditional, and in 263/// Thumb-2 mode. The epilogue beings with the first instruction 264/// after the IT opcode. 265/// Epilogue Start Index : 8-bit field indicating the byte index of the first 266/// unwind code describing the epilogue 267/// 268/// 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 269/// 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 270/// +---------------+---------------+---------------+---------------+ 271/// | Unwind Code 3 | Unwind Code 2 | Unwind Code 1 | Unwind Code 0 | 272/// +---------------+---------------+---------------+---------------+ 273/// 274/// Following the epilogue scopes, the byte code describing the unwinding 275/// follows. This is padded to align up to word alignment. Bytes are stored in 276/// little endian. 277/// 278/// 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 279/// 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 280/// +---------------------------------------------------------------+ 281/// | Exception Handler RVA (requires X = 1) | 282/// +---------------------------------------------------------------+ 283/// | (possibly followed by data required for exception handler) | 284/// +---------------------------------------------------------------+ 285/// 286/// If the X bit is set in the header, the unwind byte code is followed by the 287/// exception handler information. This constants of one Exception Handler RVA 288/// which is the address to the exception handler, followed immediately by the 289/// variable length data associated with the exception handler. 290/// 291 292struct EpilogueScope { 293 const support::ulittle32_t ES; 294 295 EpilogueScope(const support::ulittle32_t Data) : ES(Data) {} 296 uint32_t EpilogueStartOffset() const { 297 return (ES & 0x0003ffff); 298 } 299 uint8_t Res() const { 300 return ((ES & 0x000c0000) >> 18); 301 } 302 uint8_t Condition() const { 303 return ((ES & 0x00f00000) >> 20); 304 } 305 uint8_t EpilogueStartIndex() const { 306 return ((ES & 0xff000000) >> 24); 307 } 308}; 309 310struct ExceptionDataRecord; 311inline size_t HeaderWords(const ExceptionDataRecord &XR); 312 313struct ExceptionDataRecord { 314 const support::ulittle32_t *Data; 315 316 ExceptionDataRecord(const support::ulittle32_t *Data) : Data(Data) {} 317 318 uint32_t FunctionLength() const { 319 return (Data[0] & 0x0003ffff); 320 } 321 322 uint8_t Vers() const { 323 return (Data[0] & 0x000C0000) >> 18; 324 } 325 326 bool X() const { 327 return ((Data[0] & 0x00100000) >> 20); 328 } 329 330 bool E() const { 331 return ((Data[0] & 0x00200000) >> 21); 332 } 333 334 bool F() const { 335 return ((Data[0] & 0x00400000) >> 22); 336 } 337 338 uint8_t EpilogueCount() const { 339 if (HeaderWords(*this) == 1) 340 return (Data[0] & 0x0f800000) >> 23; 341 return Data[1] & 0x0000ffff; 342 } 343 344 uint8_t CodeWords() const { 345 if (HeaderWords(*this) == 1) 346 return (Data[0] & 0xf0000000) >> 28; 347 return (Data[1] & 0x00ff0000) >> 16; 348 } 349 350 ArrayRef<support::ulittle32_t> EpilogueScopes() const { 351 assert(E() == 0 && "epilogue scopes are only present when the E bit is 0"); 352 size_t Offset = HeaderWords(*this); 353 return ArrayRef<support::ulittle32_t>(&Data[Offset], EpilogueCount()); 354 } 355 356 ArrayRef<support::ulittle8_t> UnwindByteCode() const { 357 const size_t Offset = HeaderWords(*this) 358 + (E() ? 0 : EpilogueCount()); 359 const support::ulittle8_t *ByteCode = 360 reinterpret_cast<const support::ulittle8_t *>(&Data[Offset]); 361 return ArrayRef<support::ulittle8_t>(ByteCode, 362 CodeWords() * sizeof(uint32_t)); 363 } 364 365 uint32_t ExceptionHandlerRVA() const { 366 assert(X() && "Exception Handler RVA is only valid if the X bit is set"); 367 return Data[HeaderWords(*this) + EpilogueCount() + CodeWords()]; 368 } 369 370 uint32_t ExceptionHandlerParameter() const { 371 assert(X() && "Exception Handler RVA is only valid if the X bit is set"); 372 return Data[HeaderWords(*this) + EpilogueCount() + CodeWords() + 1]; 373 } 374}; 375 376inline size_t HeaderWords(const ExceptionDataRecord &XR) { 377 return (XR.Data[0] & 0xff800000) ? 1 : 2; 378} 379} 380} 381} 382 383#endif 384 385