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/Config/config.h"
16#include "llvm/Support/DataTypes.h"
17#include "llvm/Support/ErrorHandling.h"
18#include "llvm/Support/Process.h"
19
20#ifdef HAVE_SYS_MMAN_H
21#include <sys/mman.h>
22#endif
23
24#ifdef __APPLE__
25#include <mach/mach.h>
26#endif
27
28#ifdef __Fuchsia__
29#include <zircon/syscalls.h>
30#endif
31
32#if defined(__mips__)
33#  if defined(__OpenBSD__)
34#    include <mips64/sysarch.h>
35#  elif !defined(__FreeBSD__)
36#    include <sys/cachectl.h>
37#  endif
38#endif
39
40#if defined(__APPLE__)
41extern "C" void sys_icache_invalidate(const void *Addr, size_t len);
42#else
43extern "C" void __clear_cache(void *, void*);
44#endif
45
46namespace {
47
48int getPosixProtectionFlags(unsigned Flags) {
49  switch (Flags) {
50  case llvm::sys::Memory::MF_READ:
51    return PROT_READ;
52  case llvm::sys::Memory::MF_WRITE:
53    return PROT_WRITE;
54  case llvm::sys::Memory::MF_READ|llvm::sys::Memory::MF_WRITE:
55    return PROT_READ | PROT_WRITE;
56  case llvm::sys::Memory::MF_READ|llvm::sys::Memory::MF_EXEC:
57    return PROT_READ | PROT_EXEC;
58  case llvm::sys::Memory::MF_READ | llvm::sys::Memory::MF_WRITE |
59      llvm::sys::Memory::MF_EXEC:
60    return PROT_READ | PROT_WRITE | PROT_EXEC;
61  case llvm::sys::Memory::MF_EXEC:
62#if defined(__FreeBSD__)
63    // On PowerPC, having an executable page that has no read permission
64    // can have unintended consequences.  The function InvalidateInstruction-
65    // Cache uses instructions dcbf and icbi, both of which are treated by
66    // the processor as loads.  If the page has no read permissions,
67    // executing these instructions will result in a segmentation fault.
68    // Somehow, this problem is not present on Linux, but it does happen
69    // on FreeBSD.
70    return PROT_READ | PROT_EXEC;
71#else
72    return PROT_EXEC;
73#endif
74  default:
75    llvm_unreachable("Illegal memory protection flag specified!");
76  }
77  // Provide a default return value as required by some compilers.
78  return PROT_NONE;
79}
80
81} // anonymous namespace
82
83namespace llvm {
84namespace sys {
85
86MemoryBlock
87Memory::allocateMappedMemory(size_t NumBytes,
88                             const MemoryBlock *const NearBlock,
89                             unsigned PFlags,
90                             std::error_code &EC) {
91  EC = std::error_code();
92  if (NumBytes == 0)
93    return MemoryBlock();
94
95  static const size_t PageSize = Process::getPageSize();
96  const size_t NumPages = (NumBytes+PageSize-1)/PageSize;
97
98  int fd = -1;
99
100  int MMFlags = MAP_PRIVATE |
101#ifdef MAP_ANONYMOUS
102  MAP_ANONYMOUS
103#else
104  MAP_ANON
105#endif
106  ; // Ends statement above
107
108  int Protect = getPosixProtectionFlags(PFlags);
109
110#if defined(__NetBSD__) && defined(PROT_MPROTECT)
111  Protect |= PROT_MPROTECT(PROT_READ | PROT_WRITE | PROT_EXEC);
112#endif
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  // Rely on protectMappedMemory to invalidate instruction cache.
135  if (PFlags & MF_EXEC) {
136    EC = Memory::protectMappedMemory (Result, PFlags);
137    if (EC != std::error_code())
138      return MemoryBlock();
139  }
140
141  return Result;
142}
143
144std::error_code
145Memory::releaseMappedMemory(MemoryBlock &M) {
146  if (M.Address == nullptr || M.Size == 0)
147    return std::error_code();
148
149  if (0 != ::munmap(M.Address, M.Size))
150    return std::error_code(errno, std::generic_category());
151
152  M.Address = nullptr;
153  M.Size = 0;
154
155  return std::error_code();
156}
157
158std::error_code
159Memory::protectMappedMemory(const MemoryBlock &M, unsigned Flags) {
160  static const size_t PageSize = Process::getPageSize();
161  if (M.Address == nullptr || M.Size == 0)
162    return std::error_code();
163
164  if (!Flags)
165    return std::error_code(EINVAL, std::generic_category());
166
167  int Protect = getPosixProtectionFlags(Flags);
168  uintptr_t Start = alignAddr((uint8_t *)M.Address - PageSize + 1, PageSize);
169  uintptr_t End = alignAddr((uint8_t *)M.Address + M.Size, PageSize);
170
171  bool InvalidateCache = (Flags & MF_EXEC);
172
173#if defined(__arm__) || defined(__aarch64__)
174  // Certain ARM implementations treat icache clear instruction as a memory read,
175  // and CPU segfaults on trying to clear cache on !PROT_READ page.  Therefore we need
176  // to temporarily add PROT_READ for the sake of flushing the instruction caches.
177  if (InvalidateCache && !(Protect & PROT_READ)) {
178    int Result = ::mprotect((void *)Start, End - Start, Protect | PROT_READ);
179    if (Result != 0)
180      return std::error_code(errno, std::generic_category());
181
182    Memory::InvalidateInstructionCache(M.Address, M.Size);
183    InvalidateCache = false;
184  }
185#endif
186
187  int Result = ::mprotect((void *)Start, End - Start, Protect);
188
189  if (Result != 0)
190    return std::error_code(errno, std::generic_category());
191
192  if (InvalidateCache)
193    Memory::InvalidateInstructionCache(M.Address, M.Size);
194
195  return std::error_code();
196}
197
198/// InvalidateInstructionCache - Before the JIT can run a block of code
199/// that has been emitted it must invalidate the instruction cache on some
200/// platforms.
201void Memory::InvalidateInstructionCache(const void *Addr,
202                                        size_t Len) {
203
204// icache invalidation for PPC and ARM.
205#if defined(__APPLE__)
206
207#  if (defined(__POWERPC__) || defined (__ppc__) || \
208       defined(_POWER) || defined(_ARCH_PPC) || defined(__arm__) || \
209       defined(__arm64__))
210  sys_icache_invalidate(const_cast<void *>(Addr), Len);
211#  endif
212
213#elif defined(__Fuchsia__)
214
215  zx_status_t Status = zx_cache_flush(Addr, Len, ZX_CACHE_FLUSH_INSN);
216  assert(Status == ZX_OK && "cannot invalidate instruction cache");
217
218#else
219
220#  if (defined(__POWERPC__) || defined (__ppc__) || \
221       defined(_POWER) || defined(_ARCH_PPC)) && defined(__GNUC__)
222  const size_t LineSize = 32;
223
224  const intptr_t Mask = ~(LineSize - 1);
225  const intptr_t StartLine = ((intptr_t) Addr) & Mask;
226  const intptr_t EndLine = ((intptr_t) Addr + Len + LineSize - 1) & Mask;
227
228  for (intptr_t Line = StartLine; Line < EndLine; Line += LineSize)
229    asm volatile("dcbf 0, %0" : : "r"(Line));
230  asm volatile("sync");
231
232  for (intptr_t Line = StartLine; Line < EndLine; Line += LineSize)
233    asm volatile("icbi 0, %0" : : "r"(Line));
234  asm volatile("isync");
235#  elif (defined(__arm__) || defined(__aarch64__) || defined(__mips__)) && \
236        defined(__GNUC__)
237  // FIXME: Can we safely always call this for __GNUC__ everywhere?
238  const char *Start = static_cast<const char *>(Addr);
239  const char *End = Start + Len;
240  __clear_cache(const_cast<char *>(Start), const_cast<char *>(End));
241#  endif
242
243#endif  // end apple
244
245  ValgrindDiscardTranslations(Addr, Len);
246}
247
248} // namespace sys
249} // namespace llvm
250