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
getFunctions()73 Functions &getFunctions() {
74 static Functions F;
75 return F;
76 }
77
78 } // anonymous namespace
79
80 static Interpreter *TheInterpreter;
81
getTypeID(Type * Ty)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.
lookupFunction(const Function * F)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
ffiTypeFor(Type * Ty)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
ffiValueFor(Type * Ty,const GenericValue & AV,void * ArgDataPtr)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
ffiInvoke(RawFunc Fn,Function * F,ArrayRef<GenericValue> ArgVals,const DataLayout & TD,GenericValue & Result)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
callExternalFunction(Function * F,ArrayRef<GenericValue> ArgVals)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*)
lle_X_atexit(FunctionType * FT,ArrayRef<GenericValue> Args)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)
lle_X_exit(FunctionType * FT,ArrayRef<GenericValue> Args)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)
lle_X_abort(FunctionType * FT,ArrayRef<GenericValue> Args)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 #if defined(__clang__)
350 #pragma clang diagnostic push
351 #pragma clang diagnostic ignored "-Wdeprecated-declarations"
352 #endif
353 // int sprintf(char *, const char *, ...) - a very rough implementation to make
354 // output useful.
lle_X_sprintf(FunctionType * FT,ArrayRef<GenericValue> Args)355 static GenericValue lle_X_sprintf(FunctionType *FT,
356 ArrayRef<GenericValue> Args) {
357 char *OutputBuffer = (char *)GVTOP(Args[0]);
358 const char *FmtStr = (const char *)GVTOP(Args[1]);
359 unsigned ArgNo = 2;
360
361 // printf should return # chars printed. This is completely incorrect, but
362 // close enough for now.
363 GenericValue GV;
364 GV.IntVal = APInt(32, strlen(FmtStr));
365 while (true) {
366 switch (*FmtStr) {
367 case 0: return GV; // Null terminator...
368 default: // Normal nonspecial character
369 sprintf(OutputBuffer++, "%c", *FmtStr++);
370 break;
371 case '\\': { // Handle escape codes
372 sprintf(OutputBuffer, "%c%c", *FmtStr, *(FmtStr+1));
373 FmtStr += 2; OutputBuffer += 2;
374 break;
375 }
376 case '%': { // Handle format specifiers
377 char FmtBuf[100] = "", Buffer[1000] = "";
378 char *FB = FmtBuf;
379 *FB++ = *FmtStr++;
380 char Last = *FB++ = *FmtStr++;
381 unsigned HowLong = 0;
382 while (Last != 'c' && Last != 'd' && Last != 'i' && Last != 'u' &&
383 Last != 'o' && Last != 'x' && Last != 'X' && Last != 'e' &&
384 Last != 'E' && Last != 'g' && Last != 'G' && Last != 'f' &&
385 Last != 'p' && Last != 's' && Last != '%') {
386 if (Last == 'l' || Last == 'L') HowLong++; // Keep track of l's
387 Last = *FB++ = *FmtStr++;
388 }
389 *FB = 0;
390
391 switch (Last) {
392 case '%':
393 memcpy(Buffer, "%", 2); break;
394 case 'c':
395 sprintf(Buffer, FmtBuf, uint32_t(Args[ArgNo++].IntVal.getZExtValue()));
396 break;
397 case 'd': case 'i':
398 case 'u': case 'o':
399 case 'x': case 'X':
400 if (HowLong >= 1) {
401 if (HowLong == 1 &&
402 TheInterpreter->getDataLayout().getPointerSizeInBits() == 64 &&
403 sizeof(long) < sizeof(int64_t)) {
404 // Make sure we use %lld with a 64 bit argument because we might be
405 // compiling LLI on a 32 bit compiler.
406 unsigned Size = strlen(FmtBuf);
407 FmtBuf[Size] = FmtBuf[Size-1];
408 FmtBuf[Size+1] = 0;
409 FmtBuf[Size-1] = 'l';
410 }
411 sprintf(Buffer, FmtBuf, Args[ArgNo++].IntVal.getZExtValue());
412 } else
413 sprintf(Buffer, FmtBuf,uint32_t(Args[ArgNo++].IntVal.getZExtValue()));
414 break;
415 case 'e': case 'E': case 'g': case 'G': case 'f':
416 sprintf(Buffer, FmtBuf, Args[ArgNo++].DoubleVal); break;
417 case 'p':
418 sprintf(Buffer, FmtBuf, (void*)GVTOP(Args[ArgNo++])); break;
419 case 's':
420 sprintf(Buffer, FmtBuf, (char*)GVTOP(Args[ArgNo++])); break;
421 default:
422 errs() << "<unknown printf code '" << *FmtStr << "'!>";
423 ArgNo++; break;
424 }
425 size_t Len = strlen(Buffer);
426 memcpy(OutputBuffer, Buffer, Len + 1);
427 OutputBuffer += Len;
428 }
429 break;
430 }
431 }
432 return GV;
433 }
434 #if defined(__clang__)
435 #pragma clang diagnostic pop
436 #endif
437
438 // int printf(const char *, ...) - a very rough implementation to make output
439 // useful.
lle_X_printf(FunctionType * FT,ArrayRef<GenericValue> Args)440 static GenericValue lle_X_printf(FunctionType *FT,
441 ArrayRef<GenericValue> Args) {
442 char Buffer[10000];
443 std::vector<GenericValue> NewArgs;
444 NewArgs.push_back(PTOGV((void*)&Buffer[0]));
445 llvm::append_range(NewArgs, Args);
446 GenericValue GV = lle_X_sprintf(FT, NewArgs);
447 outs() << Buffer;
448 return GV;
449 }
450
451 // int sscanf(const char *format, ...);
lle_X_sscanf(FunctionType * FT,ArrayRef<GenericValue> args)452 static GenericValue lle_X_sscanf(FunctionType *FT,
453 ArrayRef<GenericValue> args) {
454 assert(args.size() < 10 && "Only handle up to 10 args to sscanf right now!");
455
456 char *Args[10];
457 for (unsigned i = 0; i < args.size(); ++i)
458 Args[i] = (char*)GVTOP(args[i]);
459
460 GenericValue GV;
461 GV.IntVal = APInt(32, sscanf(Args[0], Args[1], Args[2], Args[3], Args[4],
462 Args[5], Args[6], Args[7], Args[8], Args[9]));
463 return GV;
464 }
465
466 // int scanf(const char *format, ...);
lle_X_scanf(FunctionType * FT,ArrayRef<GenericValue> args)467 static GenericValue lle_X_scanf(FunctionType *FT, ArrayRef<GenericValue> args) {
468 assert(args.size() < 10 && "Only handle up to 10 args to scanf right now!");
469
470 char *Args[10];
471 for (unsigned i = 0; i < args.size(); ++i)
472 Args[i] = (char*)GVTOP(args[i]);
473
474 GenericValue GV;
475 GV.IntVal = APInt(32, scanf( Args[0], Args[1], Args[2], Args[3], Args[4],
476 Args[5], Args[6], Args[7], Args[8], Args[9]));
477 return GV;
478 }
479
480 // int fprintf(FILE *, const char *, ...) - a very rough implementation to make
481 // output useful.
lle_X_fprintf(FunctionType * FT,ArrayRef<GenericValue> Args)482 static GenericValue lle_X_fprintf(FunctionType *FT,
483 ArrayRef<GenericValue> Args) {
484 assert(Args.size() >= 2);
485 char Buffer[10000];
486 std::vector<GenericValue> NewArgs;
487 NewArgs.push_back(PTOGV(Buffer));
488 NewArgs.insert(NewArgs.end(), Args.begin()+1, Args.end());
489 GenericValue GV = lle_X_sprintf(FT, NewArgs);
490
491 fputs(Buffer, (FILE *) GVTOP(Args[0]));
492 return GV;
493 }
494
lle_X_memset(FunctionType * FT,ArrayRef<GenericValue> Args)495 static GenericValue lle_X_memset(FunctionType *FT,
496 ArrayRef<GenericValue> Args) {
497 int val = (int)Args[1].IntVal.getSExtValue();
498 size_t len = (size_t)Args[2].IntVal.getZExtValue();
499 memset((void *)GVTOP(Args[0]), val, len);
500 // llvm.memset.* returns void, lle_X_* returns GenericValue,
501 // so here we return GenericValue with IntVal set to zero
502 GenericValue GV;
503 GV.IntVal = 0;
504 return GV;
505 }
506
lle_X_memcpy(FunctionType * FT,ArrayRef<GenericValue> Args)507 static GenericValue lle_X_memcpy(FunctionType *FT,
508 ArrayRef<GenericValue> Args) {
509 memcpy(GVTOP(Args[0]), GVTOP(Args[1]),
510 (size_t)(Args[2].IntVal.getLimitedValue()));
511
512 // llvm.memcpy* returns void, lle_X_* returns GenericValue,
513 // so here we return GenericValue with IntVal set to zero
514 GenericValue GV;
515 GV.IntVal = 0;
516 return GV;
517 }
518
initializeExternalFunctions()519 void Interpreter::initializeExternalFunctions() {
520 auto &Fns = getFunctions();
521 sys::ScopedLock Writer(Fns.Lock);
522 Fns.FuncNames["lle_X_atexit"] = lle_X_atexit;
523 Fns.FuncNames["lle_X_exit"] = lle_X_exit;
524 Fns.FuncNames["lle_X_abort"] = lle_X_abort;
525
526 Fns.FuncNames["lle_X_printf"] = lle_X_printf;
527 Fns.FuncNames["lle_X_sprintf"] = lle_X_sprintf;
528 Fns.FuncNames["lle_X_sscanf"] = lle_X_sscanf;
529 Fns.FuncNames["lle_X_scanf"] = lle_X_scanf;
530 Fns.FuncNames["lle_X_fprintf"] = lle_X_fprintf;
531 Fns.FuncNames["lle_X_memset"] = lle_X_memset;
532 Fns.FuncNames["lle_X_memcpy"] = lle_X_memcpy;
533 }
534