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