1//===-- RTDyldMemoryManager.cpp - Memory manager for MC-JIT -----*- C++ -*-===//
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// Implementation of the runtime dynamic memory manager base class.
10//
11//===----------------------------------------------------------------------===//
12
13#include "llvm/Config/config.h"
14#include "llvm/ExecutionEngine/RTDyldMemoryManager.h"
15#include "llvm/Support/Compiler.h"
16#include "llvm/Support/DynamicLibrary.h"
17#include "llvm/Support/ErrorHandling.h"
18#include <cstdlib>
19
20#ifdef __linux__
21  // These includes used by RTDyldMemoryManager::getPointerToNamedFunction()
22  // for Glibc trickery. See comments in this function for more information.
23  #ifdef HAVE_SYS_STAT_H
24    #include <sys/stat.h>
25  #endif
26  #include <fcntl.h>
27  #include <unistd.h>
28#endif
29
30namespace llvm {
31
32RTDyldMemoryManager::~RTDyldMemoryManager() {}
33
34// Determine whether we can register EH tables.
35#if (defined(__GNUC__) && !defined(__ARM_EABI__) && !defined(__ia64__) &&      \
36     !(defined(_AIX) && defined(__ibmxl__)) && !defined(__SEH__) &&            \
37     !defined(__USING_SJLJ_EXCEPTIONS__))
38#define HAVE_EHTABLE_SUPPORT 1
39#else
40#define HAVE_EHTABLE_SUPPORT 0
41#endif
42
43#if HAVE_EHTABLE_SUPPORT
44extern "C" void __register_frame(void *);
45extern "C" void __deregister_frame(void *);
46#else
47// The building compiler does not have __(de)register_frame but
48// it may be found at runtime in a dynamically-loaded library.
49// For example, this happens when building LLVM with Visual C++
50// but using the MingW runtime.
51static void __register_frame(void *p) {
52  static bool Searched = false;
53  static void((*rf)(void *)) = 0;
54
55  if (!Searched) {
56    Searched = true;
57    *(void **)&rf =
58        llvm::sys::DynamicLibrary::SearchForAddressOfSymbol("__register_frame");
59  }
60  if (rf)
61    rf(p);
62}
63
64static void __deregister_frame(void *p) {
65  static bool Searched = false;
66  static void((*df)(void *)) = 0;
67
68  if (!Searched) {
69    Searched = true;
70    *(void **)&df = llvm::sys::DynamicLibrary::SearchForAddressOfSymbol(
71        "__deregister_frame");
72  }
73  if (df)
74    df(p);
75}
76#endif
77
78#ifdef __APPLE__
79
80static const char *processFDE(const char *Entry, bool isDeregister) {
81  const char *P = Entry;
82  uint32_t Length = *((const uint32_t *)P);
83  P += 4;
84  uint32_t Offset = *((const uint32_t *)P);
85  if (Offset != 0) {
86    if (isDeregister)
87      __deregister_frame(const_cast<char *>(Entry));
88    else
89      __register_frame(const_cast<char *>(Entry));
90  }
91  return P + Length;
92}
93
94// This implementation handles frame registration for local targets.
95// Memory managers for remote targets should re-implement this function
96// and use the LoadAddr parameter.
97void RTDyldMemoryManager::registerEHFramesInProcess(uint8_t *Addr,
98                                                    size_t Size) {
99  // On OS X OS X __register_frame takes a single FDE as an argument.
100  // See http://lists.llvm.org/pipermail/llvm-dev/2013-April/061737.html
101  // and projects/libunwind/src/UnwindLevel1-gcc-ext.c.
102  const char *P = (const char *)Addr;
103  const char *End = P + Size;
104  do  {
105    P = processFDE(P, false);
106  } while(P != End);
107}
108
109void RTDyldMemoryManager::deregisterEHFramesInProcess(uint8_t *Addr,
110                                                      size_t Size) {
111  const char *P = (const char *)Addr;
112  const char *End = P + Size;
113  do  {
114    P = processFDE(P, true);
115  } while(P != End);
116}
117
118#else
119
120void RTDyldMemoryManager::registerEHFramesInProcess(uint8_t *Addr,
121                                                    size_t Size) {
122  // On Linux __register_frame takes a single argument:
123  // a pointer to the start of the .eh_frame section.
124
125  // How can it find the end? Because crtendS.o is linked
126  // in and it has an .eh_frame section with four zero chars.
127  __register_frame(Addr);
128}
129
130void RTDyldMemoryManager::deregisterEHFramesInProcess(uint8_t *Addr,
131                                                      size_t Size) {
132  __deregister_frame(Addr);
133}
134
135#endif
136
137void RTDyldMemoryManager::registerEHFrames(uint8_t *Addr, uint64_t LoadAddr,
138                                          size_t Size) {
139  registerEHFramesInProcess(Addr, Size);
140  EHFrames.push_back({Addr, Size});
141}
142
143void RTDyldMemoryManager::deregisterEHFrames() {
144  for (auto &Frame : EHFrames)
145    deregisterEHFramesInProcess(Frame.Addr, Frame.Size);
146  EHFrames.clear();
147}
148
149static int jit_noop() {
150  return 0;
151}
152
153// ARM math functions are statically linked on Android from libgcc.a, but not
154// available at runtime for dynamic linking. On Linux these are usually placed
155// in libgcc_s.so so can be found by normal dynamic lookup.
156#if defined(__BIONIC__) && defined(__arm__)
157// List of functions which are statically linked on Android and can be generated
158// by LLVM. This is done as a nested macro which is used once to declare the
159// imported functions with ARM_MATH_DECL and once to compare them to the
160// user-requested symbol in getSymbolAddress with ARM_MATH_CHECK. The test
161// assumes that all functions start with __aeabi_ and getSymbolAddress must be
162// modified if that changes.
163#define ARM_MATH_IMPORTS(PP) \
164  PP(__aeabi_d2f) \
165  PP(__aeabi_d2iz) \
166  PP(__aeabi_d2lz) \
167  PP(__aeabi_d2uiz) \
168  PP(__aeabi_d2ulz) \
169  PP(__aeabi_dadd) \
170  PP(__aeabi_dcmpeq) \
171  PP(__aeabi_dcmpge) \
172  PP(__aeabi_dcmpgt) \
173  PP(__aeabi_dcmple) \
174  PP(__aeabi_dcmplt) \
175  PP(__aeabi_dcmpun) \
176  PP(__aeabi_ddiv) \
177  PP(__aeabi_dmul) \
178  PP(__aeabi_dsub) \
179  PP(__aeabi_f2d) \
180  PP(__aeabi_f2iz) \
181  PP(__aeabi_f2lz) \
182  PP(__aeabi_f2uiz) \
183  PP(__aeabi_f2ulz) \
184  PP(__aeabi_fadd) \
185  PP(__aeabi_fcmpeq) \
186  PP(__aeabi_fcmpge) \
187  PP(__aeabi_fcmpgt) \
188  PP(__aeabi_fcmple) \
189  PP(__aeabi_fcmplt) \
190  PP(__aeabi_fcmpun) \
191  PP(__aeabi_fdiv) \
192  PP(__aeabi_fmul) \
193  PP(__aeabi_fsub) \
194  PP(__aeabi_i2d) \
195  PP(__aeabi_i2f) \
196  PP(__aeabi_idiv) \
197  PP(__aeabi_idivmod) \
198  PP(__aeabi_l2d) \
199  PP(__aeabi_l2f) \
200  PP(__aeabi_lasr) \
201  PP(__aeabi_ldivmod) \
202  PP(__aeabi_llsl) \
203  PP(__aeabi_llsr) \
204  PP(__aeabi_lmul) \
205  PP(__aeabi_ui2d) \
206  PP(__aeabi_ui2f) \
207  PP(__aeabi_uidiv) \
208  PP(__aeabi_uidivmod) \
209  PP(__aeabi_ul2d) \
210  PP(__aeabi_ul2f) \
211  PP(__aeabi_uldivmod)
212
213// Declare statically linked math functions on ARM. The function declarations
214// here do not have the correct prototypes for each function in
215// ARM_MATH_IMPORTS, but it doesn't matter because only the symbol addresses are
216// needed. In particular the __aeabi_*divmod functions do not have calling
217// conventions which match any C prototype.
218#define ARM_MATH_DECL(name) extern "C" void name();
219ARM_MATH_IMPORTS(ARM_MATH_DECL)
220#undef ARM_MATH_DECL
221#endif
222
223#if defined(__linux__) && defined(__GLIBC__) && \
224      (defined(__i386__) || defined(__x86_64__))
225extern "C" LLVM_ATTRIBUTE_WEAK void __morestack();
226#endif
227
228uint64_t
229RTDyldMemoryManager::getSymbolAddressInProcess(const std::string &Name) {
230  // This implementation assumes that the host program is the target.
231  // Clients generating code for a remote target should implement their own
232  // memory manager.
233#if defined(__linux__) && defined(__GLIBC__)
234  //===--------------------------------------------------------------------===//
235  // Function stubs that are invoked instead of certain library calls
236  //
237  // Force the following functions to be linked in to anything that uses the
238  // JIT. This is a hack designed to work around the all-too-clever Glibc
239  // strategy of making these functions work differently when inlined vs. when
240  // not inlined, and hiding their real definitions in a separate archive file
241  // that the dynamic linker can't see. For more info, search for
242  // 'libc_nonshared.a' on Google, or read http://llvm.org/PR274.
243  if (Name == "stat") return (uint64_t)&stat;
244  if (Name == "fstat") return (uint64_t)&fstat;
245  if (Name == "lstat") return (uint64_t)&lstat;
246  if (Name == "stat64") return (uint64_t)&stat64;
247  if (Name == "fstat64") return (uint64_t)&fstat64;
248  if (Name == "lstat64") return (uint64_t)&lstat64;
249  if (Name == "atexit") return (uint64_t)&atexit;
250  if (Name == "mknod") return (uint64_t)&mknod;
251
252#if defined(__i386__) || defined(__x86_64__)
253  // __morestack lives in libgcc, a static library.
254  if (&__morestack && Name == "__morestack")
255    return (uint64_t)&__morestack;
256#endif
257#endif // __linux__ && __GLIBC__
258
259  // See ARM_MATH_IMPORTS definition for explanation
260#if defined(__BIONIC__) && defined(__arm__)
261  if (Name.compare(0, 8, "__aeabi_") == 0) {
262    // Check if the user has requested any of the functions listed in
263    // ARM_MATH_IMPORTS, and if so redirect to the statically linked symbol.
264#define ARM_MATH_CHECK(fn) if (Name == #fn) return (uint64_t)&fn;
265    ARM_MATH_IMPORTS(ARM_MATH_CHECK)
266#undef ARM_MATH_CHECK
267  }
268#endif
269
270  // We should not invoke parent's ctors/dtors from generated main()!
271  // On Mingw and Cygwin, the symbol __main is resolved to
272  // callee's(eg. tools/lli) one, to invoke wrong duplicated ctors
273  // (and register wrong callee's dtors with atexit(3)).
274  // We expect ExecutionEngine::runStaticConstructorsDestructors()
275  // is called before ExecutionEngine::runFunctionAsMain() is called.
276  if (Name == "__main") return (uint64_t)&jit_noop;
277
278  const char *NameStr = Name.c_str();
279
280  // DynamicLibrary::SearchForAddresOfSymbol expects an unmangled 'C' symbol
281  // name so ff we're on Darwin, strip the leading '_' off.
282#ifdef __APPLE__
283  if (NameStr[0] == '_')
284    ++NameStr;
285#endif
286
287  return (uint64_t)sys::DynamicLibrary::SearchForAddressOfSymbol(NameStr);
288}
289
290void *RTDyldMemoryManager::getPointerToNamedFunction(const std::string &Name,
291                                                     bool AbortOnFailure) {
292  uint64_t Addr = getSymbolAddress(Name);
293
294  if (!Addr && AbortOnFailure)
295    report_fatal_error("Program used external function '" + Name +
296                       "' which could not be resolved!");
297
298  return (void*)Addr;
299}
300
301void RTDyldMemoryManager::anchor() {}
302void MCJITMemoryManager::anchor() {}
303} // namespace llvm
304