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#  elif !defined(__FreeBSD__)
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#if defined(__NetBSD__) && defined(PROT_MPROTECT)
106  Protect |= PROT_MPROTECT(PROT_READ | PROT_WRITE | PROT_EXEC);
107#endif
108
109  // Use any near hint and the page size to set a page-aligned starting address
110  uintptr_t Start = NearBlock ? reinterpret_cast<uintptr_t>(NearBlock->base()) +
111                                      NearBlock->size() : 0;
112  if (Start && Start % PageSize)
113    Start += PageSize - Start % PageSize;
114
115  void *Addr = ::mmap(reinterpret_cast<void*>(Start), PageSize*NumPages,
116                      Protect, MMFlags, fd, 0);
117  if (Addr == MAP_FAILED) {
118    if (NearBlock) //Try again without a near hint
119      return allocateMappedMemory(NumBytes, nullptr, PFlags, EC);
120
121    EC = std::error_code(errno, std::generic_category());
122    return MemoryBlock();
123  }
124
125  MemoryBlock Result;
126  Result.Address = Addr;
127  Result.Size = NumPages*PageSize;
128
129  // Rely on protectMappedMemory to invalidate instruction cache.
130  if (PFlags & MF_EXEC) {
131    EC = Memory::protectMappedMemory (Result, PFlags);
132    if (EC != std::error_code())
133      return MemoryBlock();
134  }
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  static const size_t PageSize = Process::getPageSize();
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  uintptr_t Start = alignAddr((uint8_t *)M.Address - PageSize + 1, PageSize);
164  uintptr_t End = alignAddr((uint8_t *)M.Address + M.Size, PageSize);
165
166  bool InvalidateCache = (Flags & MF_EXEC);
167
168#if defined(__arm__) || defined(__aarch64__)
169  // Certain ARM implementations treat icache clear instruction as a memory read,
170  // and CPU segfaults on trying to clear cache on !PROT_READ page.  Therefore we need
171  // to temporarily add PROT_READ for the sake of flushing the instruction caches.
172  if (InvalidateCache && !(Protect & PROT_READ)) {
173    int Result = ::mprotect((void *)Start, End - Start, Protect | PROT_READ);
174    if (Result != 0)
175      return std::error_code(errno, std::generic_category());
176
177    Memory::InvalidateInstructionCache(M.Address, M.Size);
178    InvalidateCache = false;
179  }
180#endif
181
182  int Result = ::mprotect((void *)Start, End - Start, Protect);
183
184  if (Result != 0)
185    return std::error_code(errno, std::generic_category());
186
187  if (InvalidateCache)
188    Memory::InvalidateInstructionCache(M.Address, M.Size);
189
190  return std::error_code();
191}
192
193/// InvalidateInstructionCache - Before the JIT can run a block of code
194/// that has been emitted it must invalidate the instruction cache on some
195/// platforms.
196void Memory::InvalidateInstructionCache(const void *Addr,
197                                        size_t Len) {
198
199// icache invalidation for PPC and ARM.
200#if defined(__APPLE__)
201
202#  if (defined(__POWERPC__) || defined (__ppc__) || \
203       defined(_POWER) || defined(_ARCH_PPC) || defined(__arm__) || \
204       defined(__arm64__))
205  sys_icache_invalidate(const_cast<void *>(Addr), Len);
206#  endif
207
208#else
209
210#  if (defined(__POWERPC__) || defined (__ppc__) || \
211       defined(_POWER) || defined(_ARCH_PPC)) && defined(__GNUC__)
212  const size_t LineSize = 32;
213
214  const intptr_t Mask = ~(LineSize - 1);
215  const intptr_t StartLine = ((intptr_t) Addr) & Mask;
216  const intptr_t EndLine = ((intptr_t) Addr + Len + LineSize - 1) & Mask;
217
218  for (intptr_t Line = StartLine; Line < EndLine; Line += LineSize)
219    asm volatile("dcbf 0, %0" : : "r"(Line));
220  asm volatile("sync");
221
222  for (intptr_t Line = StartLine; Line < EndLine; Line += LineSize)
223    asm volatile("icbi 0, %0" : : "r"(Line));
224  asm volatile("isync");
225#  elif (defined(__arm__) || defined(__aarch64__) || defined(__mips__)) && \
226        defined(__GNUC__)
227  // FIXME: Can we safely always call this for __GNUC__ everywhere?
228  const char *Start = static_cast<const char *>(Addr);
229  const char *End = Start + Len;
230  __clear_cache(const_cast<char *>(Start), const_cast<char *>(End));
231#  endif
232
233#endif  // end apple
234
235  ValgrindDiscardTranslations(Addr, Len);
236}
237
238} // namespace sys
239} // namespace llvm
240