1 //===-- RTDyldMemoryManager.cpp - Memory manager for MC-JIT -----*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // Implementation of the runtime dynamic memory manager base class.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/Config/config.h"
15 #include "llvm/ExecutionEngine/RTDyldMemoryManager.h"
16 #include "llvm/Support/Compiler.h"
17 #include "llvm/Support/DynamicLibrary.h"
18 #include "llvm/Support/ErrorHandling.h"
19 #include <cstdlib>
20 
21 #ifdef __linux__
22   // These includes used by RTDyldMemoryManager::getPointerToNamedFunction()
23   // for Glibc trickery. See comments in this function for more information.
24   #ifdef HAVE_SYS_STAT_H
25     #include <sys/stat.h>
26   #endif
27   #include <fcntl.h>
28   #include <unistd.h>
29 #endif
30 
31 namespace llvm {
32 
~RTDyldMemoryManager()33 RTDyldMemoryManager::~RTDyldMemoryManager() {}
34 
35 // Determine whether we can register EH tables.
36 #if (defined(__GNUC__) && !defined(__ARM_EABI__) && !defined(__ia64__) && \
37      !defined(__SEH__) && !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
44 extern "C" void __register_frame(void*);
45 extern "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.
__register_frame(void * p)51 void __register_frame(void *p) {
52   static bool Searched = false;
53   static void *rf = 0;
54 
55   if (!Searched) {
56     Searched = true;
57     rf = llvm::sys::DynamicLibrary::SearchForAddressOfSymbol(
58                                                       "__register_frame");
59   }
60   if (rf)
61     ((void (*)(void *))rf)(p);
62 }
63 
__deregister_frame(void * p)64 void __deregister_frame(void *p) {
65   static bool Searched = false;
66   static void *df = 0;
67 
68   if (!Searched) {
69     Searched = true;
70     df = llvm::sys::DynamicLibrary::SearchForAddressOfSymbol(
71                                                       "__deregister_frame");
72   }
73   if (df)
74     ((void (*)(void *))df)(p);
75 }
76 #endif
77 
78 #ifdef __APPLE__
79 
processFDE(const char * Entry,bool isDeregister)80 static 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.
registerEHFrames(uint8_t * Addr,uint64_t LoadAddr,size_t Size)97 void RTDyldMemoryManager::registerEHFrames(uint8_t *Addr,
98                                            uint64_t LoadAddr,
99                                            size_t Size) {
100   // On OS X OS X __register_frame takes a single FDE as an argument.
101   // See http://lists.cs.uiuc.edu/pipermail/llvmdev/2013-April/061768.html
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 
deregisterEHFrames(uint8_t * Addr,uint64_t LoadAddr,size_t Size)109 void RTDyldMemoryManager::deregisterEHFrames(uint8_t *Addr,
110                                            uint64_t LoadAddr,
111                                            size_t Size) {
112   const char *P = (const char *)Addr;
113   const char *End = P + Size;
114   do  {
115     P = processFDE(P, true);
116   } while(P != End);
117 }
118 
119 #else
120 
registerEHFrames(uint8_t * Addr,uint64_t LoadAddr,size_t Size)121 void RTDyldMemoryManager::registerEHFrames(uint8_t *Addr,
122                                            uint64_t LoadAddr,
123                                            size_t Size) {
124   // On Linux __register_frame takes a single argument:
125   // a pointer to the start of the .eh_frame section.
126 
127   // How can it find the end? Because crtendS.o is linked
128   // in and it has an .eh_frame section with four zero chars.
129   __register_frame(Addr);
130 }
131 
deregisterEHFrames(uint8_t * Addr,uint64_t LoadAddr,size_t Size)132 void RTDyldMemoryManager::deregisterEHFrames(uint8_t *Addr,
133                                            uint64_t LoadAddr,
134                                            size_t Size) {
135   __deregister_frame(Addr);
136 }
137 
138 #endif
139 
jit_noop()140 static int jit_noop() {
141   return 0;
142 }
143 
144 // ARM math functions are statically linked on Android from libgcc.a, but not
145 // available at runtime for dynamic linking. On Linux these are usually placed
146 // in libgcc_s.so so can be found by normal dynamic lookup.
147 #if defined(__BIONIC__) && defined(__arm__)
148 // List of functions which are statically linked on Android and can be generated
149 // by LLVM. This is done as a nested macro which is used once to declare the
150 // imported functions with ARM_MATH_DECL and once to compare them to the
151 // user-requested symbol in getSymbolAddress with ARM_MATH_CHECK. The test
152 // assumes that all functions start with __aeabi_ and getSymbolAddress must be
153 // modified if that changes.
154 #define ARM_MATH_IMPORTS(PP) \
155   PP(__aeabi_d2f) \
156   PP(__aeabi_d2iz) \
157   PP(__aeabi_d2lz) \
158   PP(__aeabi_d2uiz) \
159   PP(__aeabi_d2ulz) \
160   PP(__aeabi_dadd) \
161   PP(__aeabi_dcmpeq) \
162   PP(__aeabi_dcmpge) \
163   PP(__aeabi_dcmpgt) \
164   PP(__aeabi_dcmple) \
165   PP(__aeabi_dcmplt) \
166   PP(__aeabi_dcmpun) \
167   PP(__aeabi_ddiv) \
168   PP(__aeabi_dmul) \
169   PP(__aeabi_dsub) \
170   PP(__aeabi_f2d) \
171   PP(__aeabi_f2iz) \
172   PP(__aeabi_f2lz) \
173   PP(__aeabi_f2uiz) \
174   PP(__aeabi_f2ulz) \
175   PP(__aeabi_fadd) \
176   PP(__aeabi_fcmpeq) \
177   PP(__aeabi_fcmpge) \
178   PP(__aeabi_fcmpgt) \
179   PP(__aeabi_fcmple) \
180   PP(__aeabi_fcmplt) \
181   PP(__aeabi_fcmpun) \
182   PP(__aeabi_fdiv) \
183   PP(__aeabi_fmul) \
184   PP(__aeabi_fsub) \
185   PP(__aeabi_i2d) \
186   PP(__aeabi_i2f) \
187   PP(__aeabi_idiv) \
188   PP(__aeabi_idivmod) \
189   PP(__aeabi_l2d) \
190   PP(__aeabi_l2f) \
191   PP(__aeabi_lasr) \
192   PP(__aeabi_ldivmod) \
193   PP(__aeabi_llsl) \
194   PP(__aeabi_llsr) \
195   PP(__aeabi_lmul) \
196   PP(__aeabi_ui2d) \
197   PP(__aeabi_ui2f) \
198   PP(__aeabi_uidiv) \
199   PP(__aeabi_uidivmod) \
200   PP(__aeabi_ul2d) \
201   PP(__aeabi_ul2f) \
202   PP(__aeabi_uldivmod)
203 
204 // Declare statically linked math functions on ARM. The function declarations
205 // here do not have the correct prototypes for each function in
206 // ARM_MATH_IMPORTS, but it doesn't matter because only the symbol addresses are
207 // needed. In particular the __aeabi_*divmod functions do not have calling
208 // conventions which match any C prototype.
209 #define ARM_MATH_DECL(name) extern "C" void name();
210 ARM_MATH_IMPORTS(ARM_MATH_DECL)
211 #undef ARM_MATH_DECL
212 #endif
213 
214 #if defined(__linux__) && defined(__GLIBC__) && \
215       (defined(__i386__) || defined(__x86_64__))
216 extern "C" LLVM_ATTRIBUTE_WEAK void __morestack();
217 #endif
218 
219 uint64_t
getSymbolAddressInProcess(const std::string & Name)220 RTDyldMemoryManager::getSymbolAddressInProcess(const std::string &Name) {
221   // This implementation assumes that the host program is the target.
222   // Clients generating code for a remote target should implement their own
223   // memory manager.
224 #if defined(__linux__) && defined(__GLIBC__)
225   //===--------------------------------------------------------------------===//
226   // Function stubs that are invoked instead of certain library calls
227   //
228   // Force the following functions to be linked in to anything that uses the
229   // JIT. This is a hack designed to work around the all-too-clever Glibc
230   // strategy of making these functions work differently when inlined vs. when
231   // not inlined, and hiding their real definitions in a separate archive file
232   // that the dynamic linker can't see. For more info, search for
233   // 'libc_nonshared.a' on Google, or read http://llvm.org/PR274.
234   if (Name == "stat") return (uint64_t)&stat;
235   if (Name == "fstat") return (uint64_t)&fstat;
236   if (Name == "lstat") return (uint64_t)&lstat;
237   if (Name == "stat64") return (uint64_t)&stat64;
238   if (Name == "fstat64") return (uint64_t)&fstat64;
239   if (Name == "lstat64") return (uint64_t)&lstat64;
240   if (Name == "atexit") return (uint64_t)&atexit;
241   if (Name == "mknod") return (uint64_t)&mknod;
242 
243 #if defined(__i386__) || defined(__x86_64__)
244   // __morestack lives in libgcc, a static library.
245   if (&__morestack && Name == "__morestack")
246     return (uint64_t)&__morestack;
247 #endif
248 #endif // __linux__ && __GLIBC__
249 
250   // See ARM_MATH_IMPORTS definition for explanation
251 #if defined(__BIONIC__) && defined(__arm__)
252   if (Name.compare(0, 8, "__aeabi_") == 0) {
253     // Check if the user has requested any of the functions listed in
254     // ARM_MATH_IMPORTS, and if so redirect to the statically linked symbol.
255 #define ARM_MATH_CHECK(fn) if (Name == #fn) return (uint64_t)&fn;
256     ARM_MATH_IMPORTS(ARM_MATH_CHECK)
257 #undef ARM_MATH_CHECK
258   }
259 #endif
260 
261   // We should not invoke parent's ctors/dtors from generated main()!
262   // On Mingw and Cygwin, the symbol __main is resolved to
263   // callee's(eg. tools/lli) one, to invoke wrong duplicated ctors
264   // (and register wrong callee's dtors with atexit(3)).
265   // We expect ExecutionEngine::runStaticConstructorsDestructors()
266   // is called before ExecutionEngine::runFunctionAsMain() is called.
267   if (Name == "__main") return (uint64_t)&jit_noop;
268 
269   // Try to demangle Name before looking it up in the process, otherwise symbol
270   // '_<Name>' (if present) will shadow '<Name>', and there will be no way to
271   // refer to the latter.
272 
273   const char *NameStr = Name.c_str();
274 
275   if (NameStr[0] == '_')
276     if (void *Ptr = sys::DynamicLibrary::SearchForAddressOfSymbol(NameStr + 1))
277       return (uint64_t)Ptr;
278 
279   // If we Name did not require demangling, or we failed to find the demangled
280   // name, try again without demangling.
281   return (uint64_t)sys::DynamicLibrary::SearchForAddressOfSymbol(NameStr);
282 }
283 
getPointerToNamedFunction(const std::string & Name,bool AbortOnFailure)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("Program used external function '" + Name +
290                        "' which could not be resolved!");
291   return (void*)Addr;
292 }
293 
294 } // namespace llvm
295