1//===- Unix/Memory.cpp - Generic UNIX System Configuration ------*- C++ -*-===// 2// 3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4// See https://llvm.org/LICENSE.txt for license information. 5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6// 7//===----------------------------------------------------------------------===// 8// 9// This file defines some functions for various memory management utilities. 10// 11//===----------------------------------------------------------------------===// 12 13#include "Unix.h" 14#include "llvm/Config/config.h" 15#include "llvm/Support/Alignment.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(__APPLE__) 33extern "C" void sys_icache_invalidate(const void *Addr, size_t len); 34#else 35extern "C" void __clear_cache(void *, void*); 36#endif 37 38static int getPosixProtectionFlags(unsigned Flags) { 39 switch (Flags & llvm::sys::Memory::MF_RWE_MASK) { 40 case llvm::sys::Memory::MF_READ: 41 return PROT_READ; 42 case llvm::sys::Memory::MF_WRITE: 43 return PROT_WRITE; 44 case llvm::sys::Memory::MF_READ|llvm::sys::Memory::MF_WRITE: 45 return PROT_READ | PROT_WRITE; 46 case llvm::sys::Memory::MF_READ|llvm::sys::Memory::MF_EXEC: 47 return PROT_READ | PROT_EXEC; 48 case llvm::sys::Memory::MF_READ | llvm::sys::Memory::MF_WRITE | 49 llvm::sys::Memory::MF_EXEC: 50 return PROT_READ | PROT_WRITE | PROT_EXEC; 51 case llvm::sys::Memory::MF_EXEC: 52#if (defined(__FreeBSD__) || defined(__POWERPC__) || defined (__ppc__) || \ 53 defined(_POWER) || defined(_ARCH_PPC)) 54 // On PowerPC, having an executable page that has no read permission 55 // can have unintended consequences. The function InvalidateInstruction- 56 // Cache uses instructions dcbf and icbi, both of which are treated by 57 // the processor as loads. If the page has no read permissions, 58 // executing these instructions will result in a segmentation fault. 59 return PROT_READ | PROT_EXEC; 60#else 61 return PROT_EXEC; 62#endif 63 default: 64 llvm_unreachable("Illegal memory protection flag specified!"); 65 } 66 // Provide a default return value as required by some compilers. 67 return PROT_NONE; 68} 69 70namespace llvm { 71namespace sys { 72 73MemoryBlock 74Memory::allocateMappedMemory(size_t NumBytes, 75 const MemoryBlock *const NearBlock, 76 unsigned PFlags, 77 std::error_code &EC) { 78 EC = std::error_code(); 79 if (NumBytes == 0) 80 return MemoryBlock(); 81 82 // On platforms that have it, we can use MAP_ANON to get a memory-mapped 83 // page without file backing, but we need a fallback of opening /dev/zero 84 // for strictly POSIX platforms instead. 85 int fd; 86#if defined(MAP_ANON) 87 fd = -1; 88#else 89 fd = open("/dev/zero", O_RDWR); 90 if (fd == -1) { 91 EC = std::error_code(errno, std::generic_category()); 92 return MemoryBlock(); 93 } 94#endif 95 96 int MMFlags = MAP_PRIVATE; 97#if defined(MAP_ANON) 98 MMFlags |= MAP_ANON; 99#endif 100 int Protect = getPosixProtectionFlags(PFlags); 101 102#if defined(__NetBSD__) && defined(PROT_MPROTECT) 103 Protect |= PROT_MPROTECT(PROT_READ | PROT_WRITE | PROT_EXEC); 104#endif 105 106 // Use any near hint and the page size to set a page-aligned starting address 107 uintptr_t Start = NearBlock ? reinterpret_cast<uintptr_t>(NearBlock->base()) + 108 NearBlock->allocatedSize() : 0; 109 static const size_t PageSize = Process::getPageSizeEstimate(); 110 const size_t NumPages = (NumBytes+PageSize-1)/PageSize; 111 112 if (Start && Start % PageSize) 113 Start += PageSize - Start % PageSize; 114 115 // FIXME: Handle huge page requests (MF_HUGE_HINT). 116 void *Addr = ::mmap(reinterpret_cast<void *>(Start), PageSize*NumPages, Protect, 117 MMFlags, fd, 0); 118 if (Addr == MAP_FAILED) { 119 if (NearBlock) { //Try again without a near hint 120#if !defined(MAP_ANON) 121 close(fd); 122#endif 123 return allocateMappedMemory(NumBytes, nullptr, PFlags, EC); 124 } 125 126 EC = std::error_code(errno, std::generic_category()); 127#if !defined(MAP_ANON) 128 close(fd); 129#endif 130 return MemoryBlock(); 131 } 132 133#if !defined(MAP_ANON) 134 close(fd); 135#endif 136 137 MemoryBlock Result; 138 Result.Address = Addr; 139 Result.AllocatedSize = PageSize*NumPages; 140 Result.Flags = PFlags; 141 142 // Rely on protectMappedMemory to invalidate instruction cache. 143 if (PFlags & MF_EXEC) { 144 EC = Memory::protectMappedMemory (Result, PFlags); 145 if (EC != std::error_code()) 146 return MemoryBlock(); 147 } 148 149 return Result; 150} 151 152std::error_code 153Memory::releaseMappedMemory(MemoryBlock &M) { 154 if (M.Address == nullptr || M.AllocatedSize == 0) 155 return std::error_code(); 156 157 if (0 != ::munmap(M.Address, M.AllocatedSize)) 158 return std::error_code(errno, std::generic_category()); 159 160 M.Address = nullptr; 161 M.AllocatedSize = 0; 162 163 return std::error_code(); 164} 165 166std::error_code 167Memory::protectMappedMemory(const MemoryBlock &M, unsigned Flags) { 168 static const Align PageSize = Align(Process::getPageSizeEstimate()); 169 if (M.Address == nullptr || M.AllocatedSize == 0) 170 return std::error_code(); 171 172 if (!Flags) 173 return std::error_code(EINVAL, std::generic_category()); 174 175 int Protect = getPosixProtectionFlags(Flags); 176 uintptr_t Start = alignAddr((const uint8_t *)M.Address - PageSize.value() + 1, PageSize); 177 uintptr_t End = alignAddr((const uint8_t *)M.Address + M.AllocatedSize, PageSize); 178 179 bool InvalidateCache = (Flags & MF_EXEC); 180 181#if defined(__arm__) || defined(__aarch64__) 182 // Certain ARM implementations treat icache clear instruction as a memory read, 183 // and CPU segfaults on trying to clear cache on !PROT_READ page. Therefore we need 184 // to temporarily add PROT_READ for the sake of flushing the instruction caches. 185 if (InvalidateCache && !(Protect & PROT_READ)) { 186 int Result = ::mprotect((void *)Start, End - Start, Protect | PROT_READ); 187 if (Result != 0) 188 return std::error_code(errno, std::generic_category()); 189 190 Memory::InvalidateInstructionCache(M.Address, M.AllocatedSize); 191 InvalidateCache = false; 192 } 193#endif 194 195 int Result = ::mprotect((void *)Start, End - Start, Protect); 196 197 if (Result != 0) 198 return std::error_code(errno, std::generic_category()); 199 200 if (InvalidateCache) 201 Memory::InvalidateInstructionCache(M.Address, M.AllocatedSize); 202 203 return std::error_code(); 204} 205 206/// InvalidateInstructionCache - Before the JIT can run a block of code 207/// that has been emitted it must invalidate the instruction cache on some 208/// platforms. 209void Memory::InvalidateInstructionCache(const void *Addr, 210 size_t Len) { 211 212// icache invalidation for PPC and ARM. 213#if defined(__APPLE__) 214 215# if (defined(__POWERPC__) || defined (__ppc__) || \ 216 defined(_POWER) || defined(_ARCH_PPC) || defined(__arm__) || \ 217 defined(__arm64__)) 218 sys_icache_invalidate(const_cast<void *>(Addr), Len); 219# endif 220 221#elif defined(__Fuchsia__) 222 223 zx_status_t Status = zx_cache_flush(Addr, Len, ZX_CACHE_FLUSH_INSN); 224 assert(Status == ZX_OK && "cannot invalidate instruction cache"); 225 226#else 227 228# if (defined(__POWERPC__) || defined (__ppc__) || \ 229 defined(_POWER) || defined(_ARCH_PPC)) && defined(__GNUC__) 230 const size_t LineSize = 32; 231 232 const intptr_t Mask = ~(LineSize - 1); 233 const intptr_t StartLine = ((intptr_t) Addr) & Mask; 234 const intptr_t EndLine = ((intptr_t) Addr + Len + LineSize - 1) & Mask; 235 236 for (intptr_t Line = StartLine; Line < EndLine; Line += LineSize) 237 asm volatile("dcbf 0, %0" : : "r"(Line)); 238 asm volatile("sync"); 239 240 for (intptr_t Line = StartLine; Line < EndLine; Line += LineSize) 241 asm volatile("icbi 0, %0" : : "r"(Line)); 242 asm volatile("isync"); 243# elif (defined(__arm__) || defined(__aarch64__) || defined(__mips__)) && \ 244 defined(__GNUC__) 245 // FIXME: Can we safely always call this for __GNUC__ everywhere? 246 const char *Start = static_cast<const char *>(Addr); 247 const char *End = Start + Len; 248 __clear_cache(const_cast<char *>(Start), const_cast<char *>(End)); 249# endif 250 251#endif // end apple 252 253 ValgrindDiscardTranslations(Addr, Len); 254} 255 256} // namespace sys 257} // namespace llvm 258