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
57using namespace llvm;
58
59namespace {
60
61typedef GenericValue (*ExFunc)(FunctionType *, ArrayRef<GenericValue>);
62typedef void (*RawFunc)();
63
64struct 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
73Functions &getFunctions() {
74 static Functions F;
75 return F;
76}
77
78} // anonymous namespace
79
80static Interpreter *TheInterpreter;
81
82static char getTypeID(Type *Ty) {
83 switch (Ty->getTypeID()) {
84 case Type::VoidTyID: return 'V';
85 case Type::IntegerTyID:
86 switch (cast<IntegerType>(Val: 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.
109static 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(Ty: FT->getReturnType());
115 for (Type *T : FT->params())
116 ExtName += getTypeID(Ty: 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 symbolName: ("lle_X_" + F->getName()).str());
127 if (FnPtr)
128 Fns.ExportedFunctions.insert(x: std::make_pair(x&: F, y&: FnPtr)); // Cache for later
129 return FnPtr;
130}
131
132#ifdef USE_LIBFFI
133static 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
154static 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
203static 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
269GenericValue 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(x: 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(reason: "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*)
324static GenericValue lle_X_atexit(FunctionType *FT,
325 ArrayRef<GenericValue> Args) {
326 assert(Args.size() == 1);
327 TheInterpreter->addAtExitHandler(F: (Function*)GVTOP(GV: Args[0]));
328 GenericValue GV;
329 GV.IntVal = 0;
330 return GV;
331}
332
333// void exit(int)
334static GenericValue lle_X_exit(FunctionType *FT, ArrayRef<GenericValue> Args) {
335 TheInterpreter->exitCalled(GV: Args[0]);
336 return GenericValue();
337}
338
339// void abort(void)
340static 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.
355static GenericValue lle_X_sprintf(FunctionType *FT,
356 ArrayRef<GenericValue> Args) {
357 char *OutputBuffer = (char *)GVTOP(GV: Args[0]);
358 const char *FmtStr = (const char *)GVTOP(GV: 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(s: FmtStr));
365 while (true) {
366 switch (*FmtStr) {
367 case 0: return GV; // Null terminator...
368 default: // Normal nonspecial character
369 sprintf(s: OutputBuffer++, format: "%c", *FmtStr++);
370 break;
371 case '\\': { // Handle escape codes
372 sprintf(s: OutputBuffer, format: "%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(dest: Buffer, src: "%", n: 2); break;
394 case 'c':
395 sprintf(s: Buffer, format: 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(s: FmtBuf);
407 FmtBuf[Size] = FmtBuf[Size-1];
408 FmtBuf[Size+1] = 0;
409 FmtBuf[Size-1] = 'l';
410 }
411 sprintf(s: Buffer, format: FmtBuf, Args[ArgNo++].IntVal.getZExtValue());
412 } else
413 sprintf(s: Buffer, format: FmtBuf,uint32_t(Args[ArgNo++].IntVal.getZExtValue()));
414 break;
415 case 'e': case 'E': case 'g': case 'G': case 'f':
416 sprintf(s: Buffer, format: FmtBuf, Args[ArgNo++].DoubleVal); break;
417 case 'p':
418 sprintf(s: Buffer, format: FmtBuf, (void*)GVTOP(GV: Args[ArgNo++])); break;
419 case 's':
420 sprintf(s: Buffer, format: FmtBuf, (char*)GVTOP(GV: Args[ArgNo++])); break;
421 default:
422 errs() << "<unknown printf code '" << *FmtStr << "'!>";
423 ArgNo++; break;
424 }
425 size_t Len = strlen(s: Buffer);
426 memcpy(dest: OutputBuffer, src: Buffer, n: 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.
440static GenericValue lle_X_printf(FunctionType *FT,
441 ArrayRef<GenericValue> Args) {
442 char Buffer[10000];
443 std::vector<GenericValue> NewArgs;
444 NewArgs.push_back(x: PTOGV(P: (void*)&Buffer[0]));
445 llvm::append_range(C&: NewArgs, R&: Args);
446 GenericValue GV = lle_X_sprintf(FT, Args: NewArgs);
447 outs() << Buffer;
448 return GV;
449}
450
451// int sscanf(const char *format, ...);
452static 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(GV: args[i]);
459
460 GenericValue GV;
461 GV.IntVal = APInt(32, sscanf(s: Args[0], format: 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, ...);
467static 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(GV: args[i]);
473
474 GenericValue GV;
475 GV.IntVal = APInt(32, scanf( format: 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.
482static 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(x: PTOGV(P: Buffer));
488 llvm::append_range(C&: NewArgs, R: llvm::drop_begin(RangeOrContainer&: Args));
489 GenericValue GV = lle_X_sprintf(FT, Args: NewArgs);
490
491 fputs(s: Buffer, stream: (FILE *) GVTOP(GV: Args[0]));
492 return GV;
493}
494
495static 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(s: (void *)GVTOP(GV: Args[0]), c: val, n: 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
507static GenericValue lle_X_memcpy(FunctionType *FT,
508 ArrayRef<GenericValue> Args) {
509 memcpy(dest: GVTOP(GV: Args[0]), src: GVTOP(GV: Args[1]),
510 n: (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
519void 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