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
35extern "C" void sys_icache_invalidate(const void *Addr, size_t len);
36
37namespace {
38
39int getPosixProtectionFlags(unsigned Flags) {
40  switch (Flags) {
41  case llvm::sys::Memory::MF_READ:
42    return PROT_READ;
43  case llvm::sys::Memory::MF_WRITE:
44    return PROT_WRITE;
45  case llvm::sys::Memory::MF_READ|llvm::sys::Memory::MF_WRITE:
46    return PROT_READ | PROT_WRITE;
47  case llvm::sys::Memory::MF_READ|llvm::sys::Memory::MF_EXEC:
48    return PROT_READ | PROT_EXEC;
49  case llvm::sys::Memory::MF_READ |
50	 llvm::sys::Memory::MF_WRITE |
51	 llvm::sys::Memory::MF_EXEC:
52    return PROT_READ | PROT_WRITE | PROT_EXEC;
53  case llvm::sys::Memory::MF_EXEC:
54#if defined(__FreeBSD__)
55    // On PowerPC, having an executable page that has no read permission
56    // can have unintended consequences.  The function InvalidateInstruction-
57    // Cache uses instructions dcbf and icbi, both of which are treated by
58    // the processor as loads.  If the page has no read permissions,
59    // executing these instructions will result in a segmentation fault.
60    // Somehow, this problem is not present on Linux, but it does happen
61    // on FreeBSD.
62    return PROT_READ | PROT_EXEC;
63#else
64    return PROT_EXEC;
65#endif
66  default:
67    llvm_unreachable("Illegal memory protection flag specified!");
68  }
69  // Provide a default return value as required by some compilers.
70  return PROT_NONE;
71}
72
73} // namespace
74
75namespace llvm {
76namespace sys {
77
78MemoryBlock
79Memory::allocateMappedMemory(size_t NumBytes,
80                             const MemoryBlock *const NearBlock,
81                             unsigned PFlags,
82                             error_code &EC) {
83  EC = error_code::success();
84  if (NumBytes == 0)
85    return MemoryBlock();
86
87  static const size_t PageSize = process::get_self()->page_size();
88  const size_t NumPages = (NumBytes+PageSize-1)/PageSize;
89
90  int fd = -1;
91#ifdef NEED_DEV_ZERO_FOR_MMAP
92  static int zero_fd = open("/dev/zero", O_RDWR);
93  if (zero_fd == -1) {
94    EC = error_code(errno, system_category());
95    return MemoryBlock();
96  }
97  fd = zero_fd;
98#endif
99
100  int MMFlags = MAP_PRIVATE |
101#ifdef HAVE_MMAP_ANONYMOUS
102  MAP_ANONYMOUS
103#else
104  MAP_ANON
105#endif
106  ; // Ends statement above
107
108  int Protect = getPosixProtectionFlags(PFlags);
109
110  // Use any near hint and the page size to set a page-aligned starting address
111  uintptr_t Start = NearBlock ? reinterpret_cast<uintptr_t>(NearBlock->base()) +
112                                      NearBlock->size() : 0;
113  if (Start && Start % PageSize)
114    Start += PageSize - Start % PageSize;
115
116  void *Addr = ::mmap(reinterpret_cast<void*>(Start), PageSize*NumPages,
117                      Protect, MMFlags, fd, 0);
118  if (Addr == MAP_FAILED) {
119    if (NearBlock) //Try again without a near hint
120      return allocateMappedMemory(NumBytes, 0, PFlags, EC);
121
122    EC = error_code(errno, system_category());
123    return MemoryBlock();
124  }
125
126  MemoryBlock Result;
127  Result.Address = Addr;
128  Result.Size = NumPages*PageSize;
129
130  if (PFlags & MF_EXEC)
131    Memory::InvalidateInstructionCache(Result.Address, Result.Size);
132
133  return Result;
134}
135
136error_code
137Memory::releaseMappedMemory(MemoryBlock &M) {
138  if (M.Address == 0 || M.Size == 0)
139    return error_code::success();
140
141  if (0 != ::munmap(M.Address, M.Size))
142    return error_code(errno, system_category());
143
144  M.Address = 0;
145  M.Size = 0;
146
147  return error_code::success();
148}
149
150error_code
151Memory::protectMappedMemory(const MemoryBlock &M, unsigned Flags) {
152  if (M.Address == 0 || M.Size == 0)
153    return error_code::success();
154
155  if (!Flags)
156    return error_code(EINVAL, generic_category());
157
158  int Protect = getPosixProtectionFlags(Flags);
159
160  int Result = ::mprotect(M.Address, M.Size, Protect);
161  if (Result != 0)
162    return error_code(errno, system_category());
163
164  if (Flags & MF_EXEC)
165    Memory::InvalidateInstructionCache(M.Address, M.Size);
166
167  return error_code::success();
168}
169
170/// AllocateRWX - Allocate a slab of memory with read/write/execute
171/// permissions.  This is typically used for JIT applications where we want
172/// to emit code to the memory then jump to it.  Getting this type of memory
173/// is very OS specific.
174///
175MemoryBlock
176Memory::AllocateRWX(size_t NumBytes, const MemoryBlock* NearBlock,
177                    std::string *ErrMsg) {
178  if (NumBytes == 0) return MemoryBlock();
179
180  size_t PageSize = process::get_self()->page_size();
181  size_t NumPages = (NumBytes+PageSize-1)/PageSize;
182
183  int fd = -1;
184#ifdef NEED_DEV_ZERO_FOR_MMAP
185  static int zero_fd = open("/dev/zero", O_RDWR);
186  if (zero_fd == -1) {
187    MakeErrMsg(ErrMsg, "Can't open /dev/zero device");
188    return MemoryBlock();
189  }
190  fd = zero_fd;
191#endif
192
193  int flags = MAP_PRIVATE |
194#ifdef HAVE_MMAP_ANONYMOUS
195  MAP_ANONYMOUS
196#else
197  MAP_ANON
198#endif
199  ;
200
201  void* start = NearBlock ? (unsigned char*)NearBlock->base() +
202                            NearBlock->size() : 0;
203
204#if defined(__APPLE__) && defined(__arm__)
205  void *pa = ::mmap(start, PageSize*NumPages, PROT_READ|PROT_EXEC,
206                    flags, fd, 0);
207#else
208  void *pa = ::mmap(start, PageSize*NumPages, PROT_READ|PROT_WRITE|PROT_EXEC,
209                    flags, fd, 0);
210#endif
211  if (pa == MAP_FAILED) {
212    if (NearBlock) //Try again without a near hint
213      return AllocateRWX(NumBytes, 0);
214
215    MakeErrMsg(ErrMsg, "Can't allocate RWX Memory");
216    return MemoryBlock();
217  }
218
219#if defined(__APPLE__) && defined(__arm__)
220  kern_return_t kr = vm_protect(mach_task_self(), (vm_address_t)pa,
221                                (vm_size_t)(PageSize*NumPages), 0,
222                                VM_PROT_READ | VM_PROT_EXECUTE | VM_PROT_COPY);
223  if (KERN_SUCCESS != kr) {
224    MakeErrMsg(ErrMsg, "vm_protect max RX failed");
225    return MemoryBlock();
226  }
227
228  kr = vm_protect(mach_task_self(), (vm_address_t)pa,
229                  (vm_size_t)(PageSize*NumPages), 0,
230                  VM_PROT_READ | VM_PROT_WRITE);
231  if (KERN_SUCCESS != kr) {
232    MakeErrMsg(ErrMsg, "vm_protect RW failed");
233    return MemoryBlock();
234  }
235#endif
236
237  MemoryBlock result;
238  result.Address = pa;
239  result.Size = NumPages*PageSize;
240
241  return result;
242}
243
244bool Memory::ReleaseRWX(MemoryBlock &M, std::string *ErrMsg) {
245  if (M.Address == 0 || M.Size == 0) return false;
246  if (0 != ::munmap(M.Address, M.Size))
247    return MakeErrMsg(ErrMsg, "Can't release RWX Memory");
248  return false;
249}
250
251bool Memory::setWritable (MemoryBlock &M, std::string *ErrMsg) {
252#if defined(__APPLE__) && defined(__arm__)
253  if (M.Address == 0 || M.Size == 0) return false;
254  Memory::InvalidateInstructionCache(M.Address, M.Size);
255  kern_return_t kr = vm_protect(mach_task_self(), (vm_address_t)M.Address,
256    (vm_size_t)M.Size, 0, VM_PROT_READ | VM_PROT_WRITE);
257  return KERN_SUCCESS == kr;
258#else
259  return true;
260#endif
261}
262
263bool Memory::setExecutable (MemoryBlock &M, std::string *ErrMsg) {
264#if defined(__APPLE__) && defined(__arm__)
265  if (M.Address == 0 || M.Size == 0) return false;
266  Memory::InvalidateInstructionCache(M.Address, M.Size);
267  kern_return_t kr = vm_protect(mach_task_self(), (vm_address_t)M.Address,
268    (vm_size_t)M.Size, 0, VM_PROT_READ | VM_PROT_EXECUTE | VM_PROT_COPY);
269  return KERN_SUCCESS == kr;
270#else
271  return true;
272#endif
273}
274
275bool Memory::setRangeWritable(const void *Addr, size_t Size) {
276#if defined(__APPLE__) && defined(__arm__)
277  kern_return_t kr = vm_protect(mach_task_self(), (vm_address_t)Addr,
278                                (vm_size_t)Size, 0,
279                                VM_PROT_READ | VM_PROT_WRITE);
280  return KERN_SUCCESS == kr;
281#else
282  return true;
283#endif
284}
285
286bool Memory::setRangeExecutable(const void *Addr, size_t Size) {
287#if defined(__APPLE__) && defined(__arm__)
288  kern_return_t kr = vm_protect(mach_task_self(), (vm_address_t)Addr,
289                                (vm_size_t)Size, 0,
290                                VM_PROT_READ | VM_PROT_EXECUTE | VM_PROT_COPY);
291  return KERN_SUCCESS == kr;
292#else
293  return true;
294#endif
295}
296
297/// InvalidateInstructionCache - Before the JIT can run a block of code
298/// that has been emitted it must invalidate the instruction cache on some
299/// platforms.
300void Memory::InvalidateInstructionCache(const void *Addr,
301                                        size_t Len) {
302
303// icache invalidation for PPC and ARM.
304#if defined(__APPLE__)
305
306#  if (defined(__POWERPC__) || defined (__ppc__) || \
307     defined(_POWER) || defined(_ARCH_PPC)) || defined(__arm__)
308  sys_icache_invalidate(const_cast<void *>(Addr), Len);
309#  endif
310
311#else
312
313#  if (defined(__POWERPC__) || defined (__ppc__) || \
314       defined(_POWER) || defined(_ARCH_PPC)) && defined(__GNUC__)
315  const size_t LineSize = 32;
316
317  const intptr_t Mask = ~(LineSize - 1);
318  const intptr_t StartLine = ((intptr_t) Addr) & Mask;
319  const intptr_t EndLine = ((intptr_t) Addr + Len + LineSize - 1) & Mask;
320
321  for (intptr_t Line = StartLine; Line < EndLine; Line += LineSize)
322    asm volatile("dcbf 0, %0" : : "r"(Line));
323  asm volatile("sync");
324
325  for (intptr_t Line = StartLine; Line < EndLine; Line += LineSize)
326    asm volatile("icbi 0, %0" : : "r"(Line));
327  asm volatile("isync");
328#  elif defined(__arm__) && defined(__GNUC__)
329  // FIXME: Can we safely always call this for __GNUC__ everywhere?
330  const char *Start = static_cast<const char *>(Addr);
331  const char *End = Start + Len;
332  __clear_cache(const_cast<char *>(Start), const_cast<char *>(End));
333#  elif defined(__mips__)
334  const char *Start = static_cast<const char *>(Addr);
335#    if defined(ANDROID)
336  // The declaration of "cacheflush" in Android bionic:
337  // extern int cacheflush(long start, long end, long flags);
338  const char *End = Start + Len;
339  long LStart = reinterpret_cast<long>(const_cast<char *>(Start));
340  long LEnd = reinterpret_cast<long>(const_cast<char *>(End));
341  cacheflush(LStart, LEnd, BCACHE);
342#    else
343  cacheflush(const_cast<char *>(Start), Len, BCACHE);
344#    endif
345#  endif
346
347#endif  // end apple
348
349  ValgrindDiscardTranslations(Addr, Len);
350}
351
352} // namespace sys
353} // namespace llvm
354