1 //===-- ExternalFunctions.cpp - Implement External Functions --------------===// 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 file contains both code to deal with invoking "external" functions, but 10 // also contains code that implements "exported" external functions. 11 // 12 // There are currently two mechanisms for handling external functions in the 13 // Interpreter. The first is to implement lle_* wrapper functions that are 14 // specific to well-known library functions which manually translate the 15 // arguments from GenericValues and make the call. If such a wrapper does 16 // not exist, and libffi is available, then the Interpreter will attempt to 17 // invoke the function using libffi, after finding its address. 18 // 19 //===----------------------------------------------------------------------===// 20 21 #include "Interpreter.h" 22 #include "llvm/ADT/APInt.h" 23 #include "llvm/ADT/ArrayRef.h" 24 #include "llvm/Config/config.h" // Detect libffi 25 #include "llvm/ExecutionEngine/GenericValue.h" 26 #include "llvm/IR/DataLayout.h" 27 #include "llvm/IR/DerivedTypes.h" 28 #include "llvm/IR/Function.h" 29 #include "llvm/IR/Type.h" 30 #include "llvm/Support/Casting.h" 31 #include "llvm/Support/DynamicLibrary.h" 32 #include "llvm/Support/ErrorHandling.h" 33 #include "llvm/Support/Mutex.h" 34 #include "llvm/Support/raw_ostream.h" 35 #include <cassert> 36 #include <cmath> 37 #include <csignal> 38 #include <cstdint> 39 #include <cstdio> 40 #include <cstring> 41 #include <map> 42 #include <mutex> 43 #include <string> 44 #include <utility> 45 #include <vector> 46 47 #ifdef HAVE_FFI_CALL 48 #ifdef HAVE_FFI_H 49 #include <ffi.h> 50 #define USE_LIBFFI 51 #elif HAVE_FFI_FFI_H 52 #include <ffi/ffi.h> 53 #define USE_LIBFFI 54 #endif 55 #endif 56 57 using namespace llvm; 58 59 namespace { 60 61 typedef GenericValue (*ExFunc)(FunctionType *, ArrayRef<GenericValue>); 62 typedef void (*RawFunc)(); 63 64 struct Functions { 65 sys::Mutex Lock; 66 std::map<const Function *, ExFunc> ExportedFunctions; 67 std::map<std::string, ExFunc> FuncNames; 68 #ifdef USE_LIBFFI 69 std::map<const Function *, RawFunc> RawFunctions; 70 #endif 71 }; 72 73 Functions &getFunctions() { 74 static Functions F; 75 return F; 76 } 77 78 } // anonymous namespace 79 80 static Interpreter *TheInterpreter; 81 82 static char getTypeID(Type *Ty) { 83 switch (Ty->getTypeID()) { 84 case Type::VoidTyID: return 'V'; 85 case Type::IntegerTyID: 86 switch (cast<IntegerType>(Ty)->getBitWidth()) { 87 case 1: return 'o'; 88 case 8: return 'B'; 89 case 16: return 'S'; 90 case 32: return 'I'; 91 case 64: return 'L'; 92 default: return 'N'; 93 } 94 case Type::FloatTyID: return 'F'; 95 case Type::DoubleTyID: return 'D'; 96 case Type::PointerTyID: return 'P'; 97 case Type::FunctionTyID:return 'M'; 98 case Type::StructTyID: return 'T'; 99 case Type::ArrayTyID: return 'A'; 100 default: return 'U'; 101 } 102 } 103 104 // Try to find address of external function given a Function object. 105 // Please note, that interpreter doesn't know how to assemble a 106 // real call in general case (this is JIT job), that's why it assumes, 107 // that all external functions has the same (and pretty "general") signature. 108 // The typical example of such functions are "lle_X_" ones. 109 static ExFunc lookupFunction(const Function *F) { 110 // Function not found, look it up... start by figuring out what the 111 // composite function name should be. 112 std::string ExtName = "lle_"; 113 FunctionType *FT = F->getFunctionType(); 114 ExtName += getTypeID(FT->getReturnType()); 115 for (Type *T : FT->params()) 116 ExtName += getTypeID(T); 117 ExtName += ("_" + F->getName()).str(); 118 119 auto &Fns = getFunctions(); 120 sys::ScopedLock Writer(Fns.Lock); 121 ExFunc FnPtr = Fns.FuncNames[ExtName]; 122 if (!FnPtr) 123 FnPtr = Fns.FuncNames[("lle_X_" + F->getName()).str()]; 124 if (!FnPtr) // Try calling a generic function... if it exists... 125 FnPtr = (ExFunc)(intptr_t)sys::DynamicLibrary::SearchForAddressOfSymbol( 126 ("lle_X_" + F->getName()).str()); 127 if (FnPtr) 128 Fns.ExportedFunctions.insert(std::make_pair(F, FnPtr)); // Cache for later 129 return FnPtr; 130 } 131 132 #ifdef USE_LIBFFI 133 static ffi_type *ffiTypeFor(Type *Ty) { 134 switch (Ty->getTypeID()) { 135 case Type::VoidTyID: return &ffi_type_void; 136 case Type::IntegerTyID: 137 switch (cast<IntegerType>(Ty)->getBitWidth()) { 138 case 8: return &ffi_type_sint8; 139 case 16: return &ffi_type_sint16; 140 case 32: return &ffi_type_sint32; 141 case 64: return &ffi_type_sint64; 142 } 143 llvm_unreachable("Unhandled integer type bitwidth"); 144 case Type::FloatTyID: return &ffi_type_float; 145 case Type::DoubleTyID: return &ffi_type_double; 146 case Type::PointerTyID: return &ffi_type_pointer; 147 default: break; 148 } 149 // TODO: Support other types such as StructTyID, ArrayTyID, OpaqueTyID, etc. 150 report_fatal_error("Type could not be mapped for use with libffi."); 151 return NULL; 152 } 153 154 static void *ffiValueFor(Type *Ty, const GenericValue &AV, 155 void *ArgDataPtr) { 156 switch (Ty->getTypeID()) { 157 case Type::IntegerTyID: 158 switch (cast<IntegerType>(Ty)->getBitWidth()) { 159 case 8: { 160 int8_t *I8Ptr = (int8_t *) ArgDataPtr; 161 *I8Ptr = (int8_t) AV.IntVal.getZExtValue(); 162 return ArgDataPtr; 163 } 164 case 16: { 165 int16_t *I16Ptr = (int16_t *) ArgDataPtr; 166 *I16Ptr = (int16_t) AV.IntVal.getZExtValue(); 167 return ArgDataPtr; 168 } 169 case 32: { 170 int32_t *I32Ptr = (int32_t *) ArgDataPtr; 171 *I32Ptr = (int32_t) AV.IntVal.getZExtValue(); 172 return ArgDataPtr; 173 } 174 case 64: { 175 int64_t *I64Ptr = (int64_t *) ArgDataPtr; 176 *I64Ptr = (int64_t) AV.IntVal.getZExtValue(); 177 return ArgDataPtr; 178 } 179 } 180 llvm_unreachable("Unhandled integer type bitwidth"); 181 case Type::FloatTyID: { 182 float *FloatPtr = (float *) ArgDataPtr; 183 *FloatPtr = AV.FloatVal; 184 return ArgDataPtr; 185 } 186 case Type::DoubleTyID: { 187 double *DoublePtr = (double *) ArgDataPtr; 188 *DoublePtr = AV.DoubleVal; 189 return ArgDataPtr; 190 } 191 case Type::PointerTyID: { 192 void **PtrPtr = (void **) ArgDataPtr; 193 *PtrPtr = GVTOP(AV); 194 return ArgDataPtr; 195 } 196 default: break; 197 } 198 // TODO: Support other types such as StructTyID, ArrayTyID, OpaqueTyID, etc. 199 report_fatal_error("Type value could not be mapped for use with libffi."); 200 return NULL; 201 } 202 203 static bool ffiInvoke(RawFunc Fn, Function *F, ArrayRef<GenericValue> ArgVals, 204 const DataLayout &TD, GenericValue &Result) { 205 ffi_cif cif; 206 FunctionType *FTy = F->getFunctionType(); 207 const unsigned NumArgs = F->arg_size(); 208 209 // TODO: We don't have type information about the remaining arguments, because 210 // this information is never passed into ExecutionEngine::runFunction(). 211 if (ArgVals.size() > NumArgs && F->isVarArg()) { 212 report_fatal_error("Calling external var arg function '" + F->getName() 213 + "' is not supported by the Interpreter."); 214 } 215 216 unsigned ArgBytes = 0; 217 218 std::vector<ffi_type*> args(NumArgs); 219 for (Function::const_arg_iterator A = F->arg_begin(), E = F->arg_end(); 220 A != E; ++A) { 221 const unsigned ArgNo = A->getArgNo(); 222 Type *ArgTy = FTy->getParamType(ArgNo); 223 args[ArgNo] = ffiTypeFor(ArgTy); 224 ArgBytes += TD.getTypeStoreSize(ArgTy); 225 } 226 227 SmallVector<uint8_t, 128> ArgData; 228 ArgData.resize(ArgBytes); 229 uint8_t *ArgDataPtr = ArgData.data(); 230 SmallVector<void*, 16> values(NumArgs); 231 for (Function::const_arg_iterator A = F->arg_begin(), E = F->arg_end(); 232 A != E; ++A) { 233 const unsigned ArgNo = A->getArgNo(); 234 Type *ArgTy = FTy->getParamType(ArgNo); 235 values[ArgNo] = ffiValueFor(ArgTy, ArgVals[ArgNo], ArgDataPtr); 236 ArgDataPtr += TD.getTypeStoreSize(ArgTy); 237 } 238 239 Type *RetTy = FTy->getReturnType(); 240 ffi_type *rtype = ffiTypeFor(RetTy); 241 242 if (ffi_prep_cif(&cif, FFI_DEFAULT_ABI, NumArgs, rtype, args.data()) == 243 FFI_OK) { 244 SmallVector<uint8_t, 128> ret; 245 if (RetTy->getTypeID() != Type::VoidTyID) 246 ret.resize(TD.getTypeStoreSize(RetTy)); 247 ffi_call(&cif, Fn, ret.data(), values.data()); 248 switch (RetTy->getTypeID()) { 249 case Type::IntegerTyID: 250 switch (cast<IntegerType>(RetTy)->getBitWidth()) { 251 case 8: Result.IntVal = APInt(8 , *(int8_t *) ret.data()); break; 252 case 16: Result.IntVal = APInt(16, *(int16_t*) ret.data()); break; 253 case 32: Result.IntVal = APInt(32, *(int32_t*) ret.data()); break; 254 case 64: Result.IntVal = APInt(64, *(int64_t*) ret.data()); break; 255 } 256 break; 257 case Type::FloatTyID: Result.FloatVal = *(float *) ret.data(); break; 258 case Type::DoubleTyID: Result.DoubleVal = *(double*) ret.data(); break; 259 case Type::PointerTyID: Result.PointerVal = *(void **) ret.data(); break; 260 default: break; 261 } 262 return true; 263 } 264 265 return false; 266 } 267 #endif // USE_LIBFFI 268 269 GenericValue Interpreter::callExternalFunction(Function *F, 270 ArrayRef<GenericValue> ArgVals) { 271 TheInterpreter = this; 272 273 auto &Fns = getFunctions(); 274 std::unique_lock<sys::Mutex> Guard(Fns.Lock); 275 276 // Do a lookup to see if the function is in our cache... this should just be a 277 // deferred annotation! 278 std::map<const Function *, ExFunc>::iterator FI = 279 Fns.ExportedFunctions.find(F); 280 if (ExFunc Fn = (FI == Fns.ExportedFunctions.end()) ? lookupFunction(F) 281 : FI->second) { 282 Guard.unlock(); 283 return Fn(F->getFunctionType(), ArgVals); 284 } 285 286 #ifdef USE_LIBFFI 287 std::map<const Function *, RawFunc>::iterator RF = Fns.RawFunctions.find(F); 288 RawFunc RawFn; 289 if (RF == Fns.RawFunctions.end()) { 290 RawFn = (RawFunc)(intptr_t) 291 sys::DynamicLibrary::SearchForAddressOfSymbol(std::string(F->getName())); 292 if (!RawFn) 293 RawFn = (RawFunc)(intptr_t)getPointerToGlobalIfAvailable(F); 294 if (RawFn != 0) 295 Fns.RawFunctions.insert(std::make_pair(F, RawFn)); // Cache for later 296 } else { 297 RawFn = RF->second; 298 } 299 300 Guard.unlock(); 301 302 GenericValue Result; 303 if (RawFn != 0 && ffiInvoke(RawFn, F, ArgVals, getDataLayout(), Result)) 304 return Result; 305 #endif // USE_LIBFFI 306 307 if (F->getName() == "__main") 308 errs() << "Tried to execute an unknown external function: " 309 << *F->getType() << " __main\n"; 310 else 311 report_fatal_error("Tried to execute an unknown external function: " + 312 F->getName()); 313 #ifndef USE_LIBFFI 314 errs() << "Recompiling LLVM with --enable-libffi might help.\n"; 315 #endif 316 return GenericValue(); 317 } 318 319 //===----------------------------------------------------------------------===// 320 // Functions "exported" to the running application... 321 // 322 323 // void atexit(Function*) 324 static GenericValue lle_X_atexit(FunctionType *FT, 325 ArrayRef<GenericValue> Args) { 326 assert(Args.size() == 1); 327 TheInterpreter->addAtExitHandler((Function*)GVTOP(Args[0])); 328 GenericValue GV; 329 GV.IntVal = 0; 330 return GV; 331 } 332 333 // void exit(int) 334 static GenericValue lle_X_exit(FunctionType *FT, ArrayRef<GenericValue> Args) { 335 TheInterpreter->exitCalled(Args[0]); 336 return GenericValue(); 337 } 338 339 // void abort(void) 340 static GenericValue lle_X_abort(FunctionType *FT, ArrayRef<GenericValue> Args) { 341 //FIXME: should we report or raise here? 342 //report_fatal_error("Interpreted program raised SIGABRT"); 343 raise (SIGABRT); 344 return GenericValue(); 345 } 346 347 // Silence warnings about sprintf. (See also 348 // https://github.com/llvm/llvm-project/issues/58086) 349 #pragma clang diagnostic push 350 #pragma clang diagnostic ignored "-Wdeprecated-declarations" 351 // int sprintf(char *, const char *, ...) - a very rough implementation to make 352 // output useful. 353 static GenericValue lle_X_sprintf(FunctionType *FT, 354 ArrayRef<GenericValue> Args) { 355 char *OutputBuffer = (char *)GVTOP(Args[0]); 356 const char *FmtStr = (const char *)GVTOP(Args[1]); 357 unsigned ArgNo = 2; 358 359 // printf should return # chars printed. This is completely incorrect, but 360 // close enough for now. 361 GenericValue GV; 362 GV.IntVal = APInt(32, strlen(FmtStr)); 363 while (true) { 364 switch (*FmtStr) { 365 case 0: return GV; // Null terminator... 366 default: // Normal nonspecial character 367 sprintf(OutputBuffer++, "%c", *FmtStr++); 368 break; 369 case '\\': { // Handle escape codes 370 sprintf(OutputBuffer, "%c%c", *FmtStr, *(FmtStr+1)); 371 FmtStr += 2; OutputBuffer += 2; 372 break; 373 } 374 case '%': { // Handle format specifiers 375 char FmtBuf[100] = "", Buffer[1000] = ""; 376 char *FB = FmtBuf; 377 *FB++ = *FmtStr++; 378 char Last = *FB++ = *FmtStr++; 379 unsigned HowLong = 0; 380 while (Last != 'c' && Last != 'd' && Last != 'i' && Last != 'u' && 381 Last != 'o' && Last != 'x' && Last != 'X' && Last != 'e' && 382 Last != 'E' && Last != 'g' && Last != 'G' && Last != 'f' && 383 Last != 'p' && Last != 's' && Last != '%') { 384 if (Last == 'l' || Last == 'L') HowLong++; // Keep track of l's 385 Last = *FB++ = *FmtStr++; 386 } 387 *FB = 0; 388 389 switch (Last) { 390 case '%': 391 memcpy(Buffer, "%", 2); break; 392 case 'c': 393 sprintf(Buffer, FmtBuf, uint32_t(Args[ArgNo++].IntVal.getZExtValue())); 394 break; 395 case 'd': case 'i': 396 case 'u': case 'o': 397 case 'x': case 'X': 398 if (HowLong >= 1) { 399 if (HowLong == 1 && 400 TheInterpreter->getDataLayout().getPointerSizeInBits() == 64 && 401 sizeof(long) < sizeof(int64_t)) { 402 // Make sure we use %lld with a 64 bit argument because we might be 403 // compiling LLI on a 32 bit compiler. 404 unsigned Size = strlen(FmtBuf); 405 FmtBuf[Size] = FmtBuf[Size-1]; 406 FmtBuf[Size+1] = 0; 407 FmtBuf[Size-1] = 'l'; 408 } 409 sprintf(Buffer, FmtBuf, Args[ArgNo++].IntVal.getZExtValue()); 410 } else 411 sprintf(Buffer, FmtBuf,uint32_t(Args[ArgNo++].IntVal.getZExtValue())); 412 break; 413 case 'e': case 'E': case 'g': case 'G': case 'f': 414 sprintf(Buffer, FmtBuf, Args[ArgNo++].DoubleVal); break; 415 case 'p': 416 sprintf(Buffer, FmtBuf, (void*)GVTOP(Args[ArgNo++])); break; 417 case 's': 418 sprintf(Buffer, FmtBuf, (char*)GVTOP(Args[ArgNo++])); break; 419 default: 420 errs() << "<unknown printf code '" << *FmtStr << "'!>"; 421 ArgNo++; break; 422 } 423 size_t Len = strlen(Buffer); 424 memcpy(OutputBuffer, Buffer, Len + 1); 425 OutputBuffer += Len; 426 } 427 break; 428 } 429 } 430 return GV; 431 } 432 #pragma clang diagnostic pop 433 434 // int printf(const char *, ...) - a very rough implementation to make output 435 // useful. 436 static GenericValue lle_X_printf(FunctionType *FT, 437 ArrayRef<GenericValue> Args) { 438 char Buffer[10000]; 439 std::vector<GenericValue> NewArgs; 440 NewArgs.push_back(PTOGV((void*)&Buffer[0])); 441 llvm::append_range(NewArgs, Args); 442 GenericValue GV = lle_X_sprintf(FT, NewArgs); 443 outs() << Buffer; 444 return GV; 445 } 446 447 // int sscanf(const char *format, ...); 448 static GenericValue lle_X_sscanf(FunctionType *FT, 449 ArrayRef<GenericValue> args) { 450 assert(args.size() < 10 && "Only handle up to 10 args to sscanf right now!"); 451 452 char *Args[10]; 453 for (unsigned i = 0; i < args.size(); ++i) 454 Args[i] = (char*)GVTOP(args[i]); 455 456 GenericValue GV; 457 GV.IntVal = APInt(32, sscanf(Args[0], Args[1], Args[2], Args[3], Args[4], 458 Args[5], Args[6], Args[7], Args[8], Args[9])); 459 return GV; 460 } 461 462 // int scanf(const char *format, ...); 463 static GenericValue lle_X_scanf(FunctionType *FT, ArrayRef<GenericValue> args) { 464 assert(args.size() < 10 && "Only handle up to 10 args to scanf right now!"); 465 466 char *Args[10]; 467 for (unsigned i = 0; i < args.size(); ++i) 468 Args[i] = (char*)GVTOP(args[i]); 469 470 GenericValue GV; 471 GV.IntVal = APInt(32, scanf( Args[0], Args[1], Args[2], Args[3], Args[4], 472 Args[5], Args[6], Args[7], Args[8], Args[9])); 473 return GV; 474 } 475 476 // int fprintf(FILE *, const char *, ...) - a very rough implementation to make 477 // output useful. 478 static GenericValue lle_X_fprintf(FunctionType *FT, 479 ArrayRef<GenericValue> Args) { 480 assert(Args.size() >= 2); 481 char Buffer[10000]; 482 std::vector<GenericValue> NewArgs; 483 NewArgs.push_back(PTOGV(Buffer)); 484 NewArgs.insert(NewArgs.end(), Args.begin()+1, Args.end()); 485 GenericValue GV = lle_X_sprintf(FT, NewArgs); 486 487 fputs(Buffer, (FILE *) GVTOP(Args[0])); 488 return GV; 489 } 490 491 static GenericValue lle_X_memset(FunctionType *FT, 492 ArrayRef<GenericValue> Args) { 493 int val = (int)Args[1].IntVal.getSExtValue(); 494 size_t len = (size_t)Args[2].IntVal.getZExtValue(); 495 memset((void *)GVTOP(Args[0]), val, len); 496 // llvm.memset.* returns void, lle_X_* returns GenericValue, 497 // so here we return GenericValue with IntVal set to zero 498 GenericValue GV; 499 GV.IntVal = 0; 500 return GV; 501 } 502 503 static GenericValue lle_X_memcpy(FunctionType *FT, 504 ArrayRef<GenericValue> Args) { 505 memcpy(GVTOP(Args[0]), GVTOP(Args[1]), 506 (size_t)(Args[2].IntVal.getLimitedValue())); 507 508 // llvm.memcpy* returns void, lle_X_* returns GenericValue, 509 // so here we return GenericValue with IntVal set to zero 510 GenericValue GV; 511 GV.IntVal = 0; 512 return GV; 513 } 514 515 void Interpreter::initializeExternalFunctions() { 516 auto &Fns = getFunctions(); 517 sys::ScopedLock Writer(Fns.Lock); 518 Fns.FuncNames["lle_X_atexit"] = lle_X_atexit; 519 Fns.FuncNames["lle_X_exit"] = lle_X_exit; 520 Fns.FuncNames["lle_X_abort"] = lle_X_abort; 521 522 Fns.FuncNames["lle_X_printf"] = lle_X_printf; 523 Fns.FuncNames["lle_X_sprintf"] = lle_X_sprintf; 524 Fns.FuncNames["lle_X_sscanf"] = lle_X_sscanf; 525 Fns.FuncNames["lle_X_scanf"] = lle_X_scanf; 526 Fns.FuncNames["lle_X_fprintf"] = lle_X_fprintf; 527 Fns.FuncNames["lle_X_memset"] = lle_X_memset; 528 Fns.FuncNames["lle_X_memcpy"] = lle_X_memcpy; 529 } 530