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 |
54	 llvm::sys::Memory::MF_WRITE |
55	 llvm::sys::Memory::MF_EXEC:
56    return PROT_READ | PROT_WRITE | PROT_EXEC;
57  case llvm::sys::Memory::MF_EXEC:
58#if defined(__FreeBSD__)
59    // On PowerPC, having an executable page that has no read permission
60    // can have unintended consequences.  The function InvalidateInstruction-
61    // Cache uses instructions dcbf and icbi, both of which are treated by
62    // the processor as loads.  If the page has no read permissions,
63    // executing these instructions will result in a segmentation fault.
64    // Somehow, this problem is not present on Linux, but it does happen
65    // on FreeBSD.
66    return PROT_READ | PROT_EXEC;
67#else
68    return PROT_EXEC;
69#endif
70  default:
71    llvm_unreachable("Illegal memory protection flag specified!");
72  }
73  // Provide a default return value as required by some compilers.
74  return PROT_NONE;
75}
76
77} // namespace
78
79namespace llvm {
80namespace sys {
81
82MemoryBlock
83Memory::allocateMappedMemory(size_t NumBytes,
84                             const MemoryBlock *const NearBlock,
85                             unsigned PFlags,
86                             std::error_code &EC) {
87  EC = std::error_code();
88  if (NumBytes == 0)
89    return MemoryBlock();
90
91  static const size_t PageSize = process::get_self()->page_size();
92  const size_t NumPages = (NumBytes+PageSize-1)/PageSize;
93
94  int fd = -1;
95#ifdef NEED_DEV_ZERO_FOR_MMAP
96  static int zero_fd = open("/dev/zero", O_RDWR);
97  if (zero_fd == -1) {
98    EC = std::error_code(errno, std::generic_category());
99    return MemoryBlock();
100  }
101  fd = zero_fd;
102#endif
103
104  int MMFlags = MAP_PRIVATE |
105#ifdef HAVE_MMAP_ANONYMOUS
106  MAP_ANONYMOUS
107#else
108  MAP_ANON
109#endif
110  ; // Ends statement above
111
112  int Protect = getPosixProtectionFlags(PFlags);
113
114  // Use any near hint and the page size to set a page-aligned starting address
115  uintptr_t Start = NearBlock ? reinterpret_cast<uintptr_t>(NearBlock->base()) +
116                                      NearBlock->size() : 0;
117  if (Start && Start % PageSize)
118    Start += PageSize - Start % PageSize;
119
120  void *Addr = ::mmap(reinterpret_cast<void*>(Start), PageSize*NumPages,
121                      Protect, MMFlags, fd, 0);
122  if (Addr == MAP_FAILED) {
123    if (NearBlock) //Try again without a near hint
124      return allocateMappedMemory(NumBytes, nullptr, PFlags, EC);
125
126    EC = std::error_code(errno, std::generic_category());
127    return MemoryBlock();
128  }
129
130  MemoryBlock Result;
131  Result.Address = Addr;
132  Result.Size = NumPages*PageSize;
133
134  if (PFlags & MF_EXEC)
135    Memory::InvalidateInstructionCache(Result.Address, Result.Size);
136
137  return Result;
138}
139
140std::error_code
141Memory::releaseMappedMemory(MemoryBlock &M) {
142  if (M.Address == nullptr || M.Size == 0)
143    return std::error_code();
144
145  if (0 != ::munmap(M.Address, M.Size))
146    return std::error_code(errno, std::generic_category());
147
148  M.Address = nullptr;
149  M.Size = 0;
150
151  return std::error_code();
152}
153
154std::error_code
155Memory::protectMappedMemory(const MemoryBlock &M, unsigned Flags) {
156  if (M.Address == nullptr || M.Size == 0)
157    return std::error_code();
158
159  if (!Flags)
160    return std::error_code(EINVAL, std::generic_category());
161
162  int Protect = getPosixProtectionFlags(Flags);
163
164  int Result = ::mprotect(M.Address, M.Size, Protect);
165  if (Result != 0)
166    return std::error_code(errno, std::generic_category());
167
168  if (Flags & MF_EXEC)
169    Memory::InvalidateInstructionCache(M.Address, M.Size);
170
171  return std::error_code();
172}
173
174/// AllocateRWX - Allocate a slab of memory with read/write/execute
175/// permissions.  This is typically used for JIT applications where we want
176/// to emit code to the memory then jump to it.  Getting this type of memory
177/// is very OS specific.
178///
179MemoryBlock
180Memory::AllocateRWX(size_t NumBytes, const MemoryBlock* NearBlock,
181                    std::string *ErrMsg) {
182  if (NumBytes == 0) return MemoryBlock();
183
184  size_t PageSize = process::get_self()->page_size();
185  size_t NumPages = (NumBytes+PageSize-1)/PageSize;
186
187  int fd = -1;
188#ifdef NEED_DEV_ZERO_FOR_MMAP
189  static int zero_fd = open("/dev/zero", O_RDWR);
190  if (zero_fd == -1) {
191    MakeErrMsg(ErrMsg, "Can't open /dev/zero device");
192    return MemoryBlock();
193  }
194  fd = zero_fd;
195#endif
196
197  int flags = MAP_PRIVATE |
198#ifdef HAVE_MMAP_ANONYMOUS
199  MAP_ANONYMOUS
200#else
201  MAP_ANON
202#endif
203  ;
204
205  void* start = NearBlock ? (unsigned char*)NearBlock->base() +
206                            NearBlock->size() : nullptr;
207
208#if defined(__APPLE__) && (defined(__arm__) || defined(__arm64__))
209  void *pa = ::mmap(start, PageSize*NumPages, PROT_READ|PROT_EXEC,
210                    flags, fd, 0);
211#else
212  void *pa = ::mmap(start, PageSize*NumPages, PROT_READ|PROT_WRITE|PROT_EXEC,
213                    flags, fd, 0);
214#endif
215  if (pa == MAP_FAILED) {
216    if (NearBlock) //Try again without a near hint
217      return AllocateRWX(NumBytes, nullptr);
218
219    MakeErrMsg(ErrMsg, "Can't allocate RWX Memory");
220    return MemoryBlock();
221  }
222
223#if defined(__APPLE__) && (defined(__arm__) || defined(__arm64__))
224  kern_return_t kr = vm_protect(mach_task_self(), (vm_address_t)pa,
225                                (vm_size_t)(PageSize*NumPages), 0,
226                                VM_PROT_READ | VM_PROT_EXECUTE | VM_PROT_COPY);
227  if (KERN_SUCCESS != kr) {
228    MakeErrMsg(ErrMsg, "vm_protect max RX failed");
229    return MemoryBlock();
230  }
231
232  kr = vm_protect(mach_task_self(), (vm_address_t)pa,
233                  (vm_size_t)(PageSize*NumPages), 0,
234                  VM_PROT_READ | VM_PROT_WRITE);
235  if (KERN_SUCCESS != kr) {
236    MakeErrMsg(ErrMsg, "vm_protect RW failed");
237    return MemoryBlock();
238  }
239#endif
240
241  MemoryBlock result;
242  result.Address = pa;
243  result.Size = NumPages*PageSize;
244
245  return result;
246}
247
248bool Memory::ReleaseRWX(MemoryBlock &M, std::string *ErrMsg) {
249  if (M.Address == nullptr || M.Size == 0) return false;
250  if (0 != ::munmap(M.Address, M.Size))
251    return MakeErrMsg(ErrMsg, "Can't release RWX Memory");
252  return false;
253}
254
255bool Memory::setWritable (MemoryBlock &M, std::string *ErrMsg) {
256#if defined(__APPLE__) && (defined(__arm__) || defined(__arm64__))
257  if (M.Address == 0 || M.Size == 0) return false;
258  Memory::InvalidateInstructionCache(M.Address, M.Size);
259  kern_return_t kr = vm_protect(mach_task_self(), (vm_address_t)M.Address,
260    (vm_size_t)M.Size, 0, VM_PROT_READ | VM_PROT_WRITE);
261  return KERN_SUCCESS == kr;
262#else
263  return true;
264#endif
265}
266
267bool Memory::setExecutable (MemoryBlock &M, std::string *ErrMsg) {
268#if defined(__APPLE__) && (defined(__arm__) || defined(__arm64__))
269  if (M.Address == 0 || M.Size == 0) return false;
270  Memory::InvalidateInstructionCache(M.Address, M.Size);
271  kern_return_t kr = vm_protect(mach_task_self(), (vm_address_t)M.Address,
272    (vm_size_t)M.Size, 0, VM_PROT_READ | VM_PROT_EXECUTE | VM_PROT_COPY);
273  return KERN_SUCCESS == kr;
274#elif defined(__arm__) || defined(__aarch64__)
275  Memory::InvalidateInstructionCache(M.Address, M.Size);
276  return true;
277#else
278  return true;
279#endif
280}
281
282bool Memory::setRangeWritable(const void *Addr, size_t Size) {
283#if defined(__APPLE__) && (defined(__arm__) || defined(__arm64__))
284  kern_return_t kr = vm_protect(mach_task_self(), (vm_address_t)Addr,
285                                (vm_size_t)Size, 0,
286                                VM_PROT_READ | VM_PROT_WRITE);
287  return KERN_SUCCESS == kr;
288#else
289  return true;
290#endif
291}
292
293bool Memory::setRangeExecutable(const void *Addr, size_t Size) {
294#if defined(__APPLE__) && (defined(__arm__) || defined(__arm64__))
295  kern_return_t kr = vm_protect(mach_task_self(), (vm_address_t)Addr,
296                                (vm_size_t)Size, 0,
297                                VM_PROT_READ | VM_PROT_EXECUTE | VM_PROT_COPY);
298  return KERN_SUCCESS == kr;
299#else
300  return true;
301#endif
302}
303
304/// InvalidateInstructionCache - Before the JIT can run a block of code
305/// that has been emitted it must invalidate the instruction cache on some
306/// platforms.
307void Memory::InvalidateInstructionCache(const void *Addr,
308                                        size_t Len) {
309
310// icache invalidation for PPC and ARM.
311#if defined(__APPLE__)
312
313#  if (defined(__POWERPC__) || defined (__ppc__) || \
314       defined(_POWER) || defined(_ARCH_PPC) || defined(__arm__) || \
315       defined(__arm64__))
316  sys_icache_invalidate(const_cast<void *>(Addr), Len);
317#  endif
318
319#else
320
321#  if (defined(__POWERPC__) || defined (__ppc__) || \
322       defined(_POWER) || defined(_ARCH_PPC)) && defined(__GNUC__)
323  const size_t LineSize = 32;
324
325  const intptr_t Mask = ~(LineSize - 1);
326  const intptr_t StartLine = ((intptr_t) Addr) & Mask;
327  const intptr_t EndLine = ((intptr_t) Addr + Len + LineSize - 1) & Mask;
328
329  for (intptr_t Line = StartLine; Line < EndLine; Line += LineSize)
330    asm volatile("dcbf 0, %0" : : "r"(Line));
331  asm volatile("sync");
332
333  for (intptr_t Line = StartLine; Line < EndLine; Line += LineSize)
334    asm volatile("icbi 0, %0" : : "r"(Line));
335  asm volatile("isync");
336#  elif (defined(__arm__) || defined(__aarch64__)) && defined(__GNUC__)
337  // FIXME: Can we safely always call this for __GNUC__ everywhere?
338  const char *Start = static_cast<const char *>(Addr);
339  const char *End = Start + Len;
340  __clear_cache(const_cast<char *>(Start), const_cast<char *>(End));
341#  elif defined(__mips__)
342  const char *Start = static_cast<const char *>(Addr);
343#    if defined(ANDROID)
344  // The declaration of "cacheflush" in Android bionic:
345  // extern int cacheflush(long start, long end, long flags);
346  const char *End = Start + Len;
347  long LStart = reinterpret_cast<long>(const_cast<char *>(Start));
348  long LEnd = reinterpret_cast<long>(const_cast<char *>(End));
349  cacheflush(LStart, LEnd, BCACHE);
350#    else
351  cacheflush(const_cast<char *>(Start), Len, BCACHE);
352#    endif
353#  endif
354
355#endif  // end apple
356
357  ValgrindDiscardTranslations(Addr, Len);
358}
359
360} // namespace sys
361} // namespace llvm
362