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} // 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#ifdef NEED_DEV_ZERO_FOR_MMAP
95  static int zero_fd = open("/dev/zero", O_RDWR);
96  if (zero_fd == -1) {
97    EC = std::error_code(errno, std::generic_category());
98    return MemoryBlock();
99  }
100  fd = zero_fd;
101#endif
102
103  int MMFlags = MAP_PRIVATE |
104#ifdef HAVE_MMAP_ANONYMOUS
105  MAP_ANONYMOUS
106#else
107  MAP_ANON
108#endif
109  ; // Ends statement above
110
111  int Protect = getPosixProtectionFlags(PFlags);
112
113  // Use any near hint and the page size to set a page-aligned starting address
114  uintptr_t Start = NearBlock ? reinterpret_cast<uintptr_t>(NearBlock->base()) +
115                                      NearBlock->size() : 0;
116  if (Start && Start % PageSize)
117    Start += PageSize - Start % PageSize;
118
119  void *Addr = ::mmap(reinterpret_cast<void*>(Start), PageSize*NumPages,
120                      Protect, MMFlags, fd, 0);
121  if (Addr == MAP_FAILED) {
122    if (NearBlock) //Try again without a near hint
123      return allocateMappedMemory(NumBytes, nullptr, PFlags, EC);
124
125    EC = std::error_code(errno, std::generic_category());
126    return MemoryBlock();
127  }
128
129  MemoryBlock Result;
130  Result.Address = Addr;
131  Result.Size = NumPages*PageSize;
132
133  if (PFlags & MF_EXEC)
134    Memory::InvalidateInstructionCache(Result.Address, Result.Size);
135
136  return Result;
137}
138
139std::error_code
140Memory::releaseMappedMemory(MemoryBlock &M) {
141  if (M.Address == nullptr || M.Size == 0)
142    return std::error_code();
143
144  if (0 != ::munmap(M.Address, M.Size))
145    return std::error_code(errno, std::generic_category());
146
147  M.Address = nullptr;
148  M.Size = 0;
149
150  return std::error_code();
151}
152
153std::error_code
154Memory::protectMappedMemory(const MemoryBlock &M, unsigned Flags) {
155  if (M.Address == nullptr || M.Size == 0)
156    return std::error_code();
157
158  if (!Flags)
159    return std::error_code(EINVAL, std::generic_category());
160
161  int Protect = getPosixProtectionFlags(Flags);
162
163  int Result = ::mprotect(M.Address, M.Size, Protect);
164  if (Result != 0)
165    return std::error_code(errno, std::generic_category());
166
167  if (Flags & MF_EXEC)
168    Memory::InvalidateInstructionCache(M.Address, M.Size);
169
170  return std::error_code();
171}
172
173/// AllocateRWX - Allocate a slab of memory with read/write/execute
174/// permissions.  This is typically used for JIT applications where we want
175/// to emit code to the memory then jump to it.  Getting this type of memory
176/// is very OS specific.
177///
178MemoryBlock
179Memory::AllocateRWX(size_t NumBytes, const MemoryBlock* NearBlock,
180                    std::string *ErrMsg) {
181  if (NumBytes == 0) return MemoryBlock();
182
183  size_t PageSize = Process::getPageSize();
184  size_t NumPages = (NumBytes+PageSize-1)/PageSize;
185
186  int fd = -1;
187#ifdef NEED_DEV_ZERO_FOR_MMAP
188  static int zero_fd = open("/dev/zero", O_RDWR);
189  if (zero_fd == -1) {
190    MakeErrMsg(ErrMsg, "Can't open /dev/zero device");
191    return MemoryBlock();
192  }
193  fd = zero_fd;
194#endif
195
196  int flags = MAP_PRIVATE |
197#ifdef HAVE_MMAP_ANONYMOUS
198  MAP_ANONYMOUS
199#else
200  MAP_ANON
201#endif
202  ;
203
204  void* start = NearBlock ? (unsigned char*)NearBlock->base() +
205                            NearBlock->size() : nullptr;
206
207#if defined(__APPLE__) && (defined(__arm__) || defined(__arm64__))
208  void *pa = ::mmap(start, PageSize*NumPages, PROT_READ|PROT_EXEC,
209                    flags, fd, 0);
210#else
211  void *pa = ::mmap(start, PageSize*NumPages, PROT_READ|PROT_WRITE|PROT_EXEC,
212                    flags, fd, 0);
213#endif
214  if (pa == MAP_FAILED) {
215    if (NearBlock) //Try again without a near hint
216      return AllocateRWX(NumBytes, nullptr);
217
218    MakeErrMsg(ErrMsg, "Can't allocate RWX Memory");
219    return MemoryBlock();
220  }
221
222#if defined(__APPLE__) && (defined(__arm__) || defined(__arm64__))
223  kern_return_t kr = vm_protect(mach_task_self(), (vm_address_t)pa,
224                                (vm_size_t)(PageSize*NumPages), 0,
225                                VM_PROT_READ | VM_PROT_EXECUTE | VM_PROT_COPY);
226  if (KERN_SUCCESS != kr) {
227    MakeErrMsg(ErrMsg, "vm_protect max RX failed");
228    return MemoryBlock();
229  }
230
231  kr = vm_protect(mach_task_self(), (vm_address_t)pa,
232                  (vm_size_t)(PageSize*NumPages), 0,
233                  VM_PROT_READ | VM_PROT_WRITE);
234  if (KERN_SUCCESS != kr) {
235    MakeErrMsg(ErrMsg, "vm_protect RW failed");
236    return MemoryBlock();
237  }
238#endif
239
240  MemoryBlock result;
241  result.Address = pa;
242  result.Size = NumPages*PageSize;
243
244  return result;
245}
246
247bool Memory::ReleaseRWX(MemoryBlock &M, std::string *ErrMsg) {
248  if (M.Address == nullptr || M.Size == 0) return false;
249  if (0 != ::munmap(M.Address, M.Size))
250    return MakeErrMsg(ErrMsg, "Can't release RWX Memory");
251  return false;
252}
253
254bool Memory::setWritable (MemoryBlock &M, std::string *ErrMsg) {
255#if defined(__APPLE__) && (defined(__arm__) || defined(__arm64__))
256  if (M.Address == 0 || M.Size == 0) return false;
257  Memory::InvalidateInstructionCache(M.Address, M.Size);
258  kern_return_t kr = vm_protect(mach_task_self(), (vm_address_t)M.Address,
259    (vm_size_t)M.Size, 0, VM_PROT_READ | VM_PROT_WRITE);
260  return KERN_SUCCESS == kr;
261#else
262  return true;
263#endif
264}
265
266bool Memory::setExecutable (MemoryBlock &M, std::string *ErrMsg) {
267  if (M.Address == 0 || M.Size == 0) return false;
268  Memory::InvalidateInstructionCache(M.Address, M.Size);
269#if defined(__APPLE__) && (defined(__arm__) || defined(__arm64__))
270  kern_return_t kr = vm_protect(mach_task_self(), (vm_address_t)M.Address,
271    (vm_size_t)M.Size, 0, VM_PROT_READ | VM_PROT_EXECUTE | VM_PROT_COPY);
272  return KERN_SUCCESS == kr;
273#else
274  return true;
275#endif
276}
277
278bool Memory::setRangeWritable(const void *Addr, size_t Size) {
279#if defined(__APPLE__) && (defined(__arm__) || defined(__arm64__))
280  kern_return_t kr = vm_protect(mach_task_self(), (vm_address_t)Addr,
281                                (vm_size_t)Size, 0,
282                                VM_PROT_READ | VM_PROT_WRITE);
283  return KERN_SUCCESS == kr;
284#else
285  return true;
286#endif
287}
288
289bool Memory::setRangeExecutable(const void *Addr, size_t Size) {
290#if defined(__APPLE__) && (defined(__arm__) || defined(__arm64__))
291  kern_return_t kr = vm_protect(mach_task_self(), (vm_address_t)Addr,
292                                (vm_size_t)Size, 0,
293                                VM_PROT_READ | VM_PROT_EXECUTE | VM_PROT_COPY);
294  return KERN_SUCCESS == kr;
295#else
296  return true;
297#endif
298}
299
300/// InvalidateInstructionCache - Before the JIT can run a block of code
301/// that has been emitted it must invalidate the instruction cache on some
302/// platforms.
303void Memory::InvalidateInstructionCache(const void *Addr,
304                                        size_t Len) {
305
306// icache invalidation for PPC and ARM.
307#if defined(__APPLE__)
308
309#  if (defined(__POWERPC__) || defined (__ppc__) || \
310       defined(_POWER) || defined(_ARCH_PPC) || defined(__arm__) || \
311       defined(__arm64__))
312  sys_icache_invalidate(const_cast<void *>(Addr), Len);
313#  endif
314
315#else
316
317#  if (defined(__POWERPC__) || defined (__ppc__) || \
318       defined(_POWER) || defined(_ARCH_PPC)) && defined(__GNUC__)
319  const size_t LineSize = 32;
320
321  const intptr_t Mask = ~(LineSize - 1);
322  const intptr_t StartLine = ((intptr_t) Addr) & Mask;
323  const intptr_t EndLine = ((intptr_t) Addr + Len + LineSize - 1) & Mask;
324
325  for (intptr_t Line = StartLine; Line < EndLine; Line += LineSize)
326    asm volatile("dcbf 0, %0" : : "r"(Line));
327  asm volatile("sync");
328
329  for (intptr_t Line = StartLine; Line < EndLine; Line += LineSize)
330    asm volatile("icbi 0, %0" : : "r"(Line));
331  asm volatile("isync");
332#  elif (defined(__arm__) || defined(__aarch64__) || defined(__mips__)) && \
333        defined(__GNUC__)
334  // FIXME: Can we safely always call this for __GNUC__ everywhere?
335  const char *Start = static_cast<const char *>(Addr);
336  const char *End = Start + Len;
337  __clear_cache(const_cast<char *>(Start), const_cast<char *>(End));
338#  endif
339
340#endif  // end apple
341
342  ValgrindDiscardTranslations(Addr, Len);
343}
344
345} // namespace sys
346} // namespace llvm
347