1//===- Unix/Memory.cpp - Generic UNIX System Configuration ------*- 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// This file defines some functions for various memory management utilities.
11//
12//===----------------------------------------------------------------------===//
13
14#include "Unix.h"
15#include "llvm/Support/DataTypes.h"
16#include "llvm/Support/ErrorHandling.h"
17#include "llvm/Support/Process.h"
18
19#ifdef HAVE_SYS_MMAN_H
20#include <sys/mman.h>
21#endif
22
23#ifdef __APPLE__
24#include <mach/mach.h>
25#endif
26
27#if defined(__mips__)
28#  if defined(__OpenBSD__)
29#    include <mips64/sysarch.h>
30#  else
31#    include <sys/cachectl.h>
32#  endif
33#endif
34
35#ifdef __APPLE__
36extern "C" void sys_icache_invalidate(const void *Addr, size_t len);
37#else
38extern "C" void __clear_cache(void *, void*);
39#endif
40
41namespace {
42
43int getPosixProtectionFlags(unsigned Flags) {
44  switch (Flags) {
45  case llvm::sys::Memory::MF_READ:
46    return PROT_READ;
47  case llvm::sys::Memory::MF_WRITE:
48    return PROT_WRITE;
49  case llvm::sys::Memory::MF_READ|llvm::sys::Memory::MF_WRITE:
50    return PROT_READ | PROT_WRITE;
51  case llvm::sys::Memory::MF_READ|llvm::sys::Memory::MF_EXEC:
52    return PROT_READ | PROT_EXEC;
53  case llvm::sys::Memory::MF_READ | llvm::sys::Memory::MF_WRITE |
54      llvm::sys::Memory::MF_EXEC:
55    return PROT_READ | PROT_WRITE | PROT_EXEC;
56  case llvm::sys::Memory::MF_EXEC:
57#if defined(__FreeBSD__)
58    // On PowerPC, having an executable page that has no read permission
59    // can have unintended consequences.  The function InvalidateInstruction-
60    // Cache uses instructions dcbf and icbi, both of which are treated by
61    // the processor as loads.  If the page has no read permissions,
62    // executing these instructions will result in a segmentation fault.
63    // Somehow, this problem is not present on Linux, but it does happen
64    // on FreeBSD.
65    return PROT_READ | PROT_EXEC;
66#else
67    return PROT_EXEC;
68#endif
69  default:
70    llvm_unreachable("Illegal memory protection flag specified!");
71  }
72  // Provide a default return value as required by some compilers.
73  return PROT_NONE;
74}
75
76} // anonymous namespace
77
78namespace llvm {
79namespace sys {
80
81MemoryBlock
82Memory::allocateMappedMemory(size_t NumBytes,
83                             const MemoryBlock *const NearBlock,
84                             unsigned PFlags,
85                             std::error_code &EC) {
86  EC = std::error_code();
87  if (NumBytes == 0)
88    return MemoryBlock();
89
90  static const size_t PageSize = Process::getPageSize();
91  const size_t NumPages = (NumBytes+PageSize-1)/PageSize;
92
93  int fd = -1;
94
95  int MMFlags = MAP_PRIVATE |
96#ifdef MAP_ANONYMOUS
97  MAP_ANONYMOUS
98#else
99  MAP_ANON
100#endif
101  ; // Ends statement above
102
103  int Protect = getPosixProtectionFlags(PFlags);
104
105  // Use any near hint and the page size to set a page-aligned starting address
106  uintptr_t Start = NearBlock ? reinterpret_cast<uintptr_t>(NearBlock->base()) +
107                                      NearBlock->size() : 0;
108  if (Start && Start % PageSize)
109    Start += PageSize - Start % PageSize;
110
111  void *Addr = ::mmap(reinterpret_cast<void*>(Start), PageSize*NumPages,
112                      Protect, MMFlags, fd, 0);
113  if (Addr == MAP_FAILED) {
114    if (NearBlock) //Try again without a near hint
115      return allocateMappedMemory(NumBytes, nullptr, PFlags, EC);
116
117    EC = std::error_code(errno, std::generic_category());
118    return MemoryBlock();
119  }
120
121  MemoryBlock Result;
122  Result.Address = Addr;
123  Result.Size = NumPages*PageSize;
124
125  if (PFlags & MF_EXEC)
126    Memory::InvalidateInstructionCache(Result.Address, Result.Size);
127
128  return Result;
129}
130
131std::error_code
132Memory::releaseMappedMemory(MemoryBlock &M) {
133  if (M.Address == nullptr || M.Size == 0)
134    return std::error_code();
135
136  if (0 != ::munmap(M.Address, M.Size))
137    return std::error_code(errno, std::generic_category());
138
139  M.Address = nullptr;
140  M.Size = 0;
141
142  return std::error_code();
143}
144
145std::error_code
146Memory::protectMappedMemory(const MemoryBlock &M, unsigned Flags) {
147  static const size_t PageSize = Process::getPageSize();
148  if (M.Address == nullptr || M.Size == 0)
149    return std::error_code();
150
151  if (!Flags)
152    return std::error_code(EINVAL, std::generic_category());
153
154  int Protect = getPosixProtectionFlags(Flags);
155
156  uintptr_t Start = alignAddr((uint8_t *)M.Address - PageSize + 1, PageSize);
157  uintptr_t End = alignAddr((uint8_t *)M.Address + M.Size, PageSize);
158  int Result = ::mprotect((void *)Start, End - Start, Protect);
159
160  if (Result != 0)
161    return std::error_code(errno, std::generic_category());
162
163  if (Flags & MF_EXEC)
164    Memory::InvalidateInstructionCache(M.Address, M.Size);
165
166  return std::error_code();
167}
168
169/// AllocateRWX - Allocate a slab of memory with read/write/execute
170/// permissions.  This is typically used for JIT applications where we want
171/// to emit code to the memory then jump to it.  Getting this type of memory
172/// is very OS specific.
173///
174MemoryBlock
175Memory::AllocateRWX(size_t NumBytes, const MemoryBlock* NearBlock,
176                    std::string *ErrMsg) {
177  if (NumBytes == 0) return MemoryBlock();
178
179  static const size_t PageSize = Process::getPageSize();
180  size_t NumPages = (NumBytes+PageSize-1)/PageSize;
181
182  int fd = -1;
183
184  int flags = MAP_PRIVATE |
185#ifdef MAP_ANONYMOUS
186  MAP_ANONYMOUS
187#else
188  MAP_ANON
189#endif
190  ;
191
192  void* start = NearBlock ? (unsigned char*)NearBlock->base() +
193                            NearBlock->size() : nullptr;
194
195#if defined(__APPLE__) && (defined(__arm__) || defined(__arm64__))
196  void *pa = ::mmap(start, PageSize*NumPages, PROT_READ|PROT_EXEC,
197                    flags, fd, 0);
198#elif defined(__NetBSD__) && defined(PROT_MPROTECT)
199  void *pa =
200      ::mmap(start, PageSize * NumPages,
201             PROT_READ | PROT_WRITE | PROT_MPROTECT(PROT_EXEC), flags, fd, 0);
202#else
203  void *pa = ::mmap(start, PageSize*NumPages, PROT_READ|PROT_WRITE|PROT_EXEC,
204                    flags, fd, 0);
205#endif
206  if (pa == MAP_FAILED) {
207    if (NearBlock) //Try again without a near hint
208      return AllocateRWX(NumBytes, nullptr);
209
210    MakeErrMsg(ErrMsg, "Can't allocate RWX Memory");
211    return MemoryBlock();
212  }
213
214#if defined(__APPLE__) && (defined(__arm__) || defined(__arm64__))
215  kern_return_t kr = vm_protect(mach_task_self(), (vm_address_t)pa,
216                                (vm_size_t)(PageSize*NumPages), 0,
217                                VM_PROT_READ | VM_PROT_EXECUTE | VM_PROT_COPY);
218  if (KERN_SUCCESS != kr) {
219    MakeErrMsg(ErrMsg, "vm_protect max RX failed");
220    return MemoryBlock();
221  }
222
223  kr = vm_protect(mach_task_self(), (vm_address_t)pa,
224                  (vm_size_t)(PageSize*NumPages), 0,
225                  VM_PROT_READ | VM_PROT_WRITE);
226  if (KERN_SUCCESS != kr) {
227    MakeErrMsg(ErrMsg, "vm_protect RW failed");
228    return MemoryBlock();
229  }
230#endif
231
232  MemoryBlock result;
233  result.Address = pa;
234  result.Size = NumPages*PageSize;
235
236  return result;
237}
238
239bool Memory::ReleaseRWX(MemoryBlock &M, std::string *ErrMsg) {
240  if (M.Address == nullptr || M.Size == 0) return false;
241  if (0 != ::munmap(M.Address, M.Size))
242    return MakeErrMsg(ErrMsg, "Can't release RWX Memory");
243  return false;
244}
245
246bool Memory::setWritable (MemoryBlock &M, std::string *ErrMsg) {
247#if defined(__APPLE__) && (defined(__arm__) || defined(__arm64__))
248  if (M.Address == 0 || M.Size == 0) return false;
249  Memory::InvalidateInstructionCache(M.Address, M.Size);
250  kern_return_t kr = vm_protect(mach_task_self(), (vm_address_t)M.Address,
251    (vm_size_t)M.Size, 0, VM_PROT_READ | VM_PROT_WRITE);
252  return KERN_SUCCESS == kr;
253#else
254  return true;
255#endif
256}
257
258bool Memory::setExecutable (MemoryBlock &M, std::string *ErrMsg) {
259  if (M.Address == nullptr || M.Size == 0) return false;
260  Memory::InvalidateInstructionCache(M.Address, M.Size);
261#if defined(__APPLE__) && (defined(__arm__) || defined(__arm64__))
262  kern_return_t kr = vm_protect(mach_task_self(), (vm_address_t)M.Address,
263    (vm_size_t)M.Size, 0, VM_PROT_READ | VM_PROT_EXECUTE | VM_PROT_COPY);
264  return KERN_SUCCESS == kr;
265#else
266  return true;
267#endif
268}
269
270bool Memory::setRangeWritable(const void *Addr, size_t Size) {
271#if defined(__APPLE__) && (defined(__arm__) || defined(__arm64__))
272  kern_return_t kr = vm_protect(mach_task_self(), (vm_address_t)Addr,
273                                (vm_size_t)Size, 0,
274                                VM_PROT_READ | VM_PROT_WRITE);
275  return KERN_SUCCESS == kr;
276#else
277  return true;
278#endif
279}
280
281bool Memory::setRangeExecutable(const void *Addr, size_t Size) {
282#if defined(__APPLE__) && (defined(__arm__) || defined(__arm64__))
283  kern_return_t kr = vm_protect(mach_task_self(), (vm_address_t)Addr,
284                                (vm_size_t)Size, 0,
285                                VM_PROT_READ | VM_PROT_EXECUTE | VM_PROT_COPY);
286  return KERN_SUCCESS == kr;
287#else
288  return true;
289#endif
290}
291
292/// InvalidateInstructionCache - Before the JIT can run a block of code
293/// that has been emitted it must invalidate the instruction cache on some
294/// platforms.
295void Memory::InvalidateInstructionCache(const void *Addr,
296                                        size_t Len) {
297
298// icache invalidation for PPC and ARM.
299#if defined(__APPLE__)
300
301#  if (defined(__POWERPC__) || defined (__ppc__) || \
302       defined(_POWER) || defined(_ARCH_PPC) || defined(__arm__) || \
303       defined(__arm64__))
304  sys_icache_invalidate(const_cast<void *>(Addr), Len);
305#  endif
306
307#else
308
309#  if (defined(__POWERPC__) || defined (__ppc__) || \
310       defined(_POWER) || defined(_ARCH_PPC)) && defined(__GNUC__)
311  const size_t LineSize = 32;
312
313  const intptr_t Mask = ~(LineSize - 1);
314  const intptr_t StartLine = ((intptr_t) Addr) & Mask;
315  const intptr_t EndLine = ((intptr_t) Addr + Len + LineSize - 1) & Mask;
316
317  for (intptr_t Line = StartLine; Line < EndLine; Line += LineSize)
318    asm volatile("dcbf 0, %0" : : "r"(Line));
319  asm volatile("sync");
320
321  for (intptr_t Line = StartLine; Line < EndLine; Line += LineSize)
322    asm volatile("icbi 0, %0" : : "r"(Line));
323  asm volatile("isync");
324#  elif (defined(__arm__) || defined(__aarch64__) || defined(__mips__)) && \
325        defined(__GNUC__)
326  // FIXME: Can we safely always call this for __GNUC__ everywhere?
327  const char *Start = static_cast<const char *>(Addr);
328  const char *End = Start + Len;
329  __clear_cache(const_cast<char *>(Start), const_cast<char *>(End));
330#  endif
331
332#endif  // end apple
333
334  ValgrindDiscardTranslations(Addr, Len);
335}
336
337} // namespace sys
338} // namespace llvm
339