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#include "llvm/Support/Valgrind.h" 20 21#ifdef HAVE_SYS_MMAN_H 22#include <sys/mman.h> 23#endif 24 25#ifdef __APPLE__ 26#include <mach/mach.h> 27#endif 28 29#ifdef __Fuchsia__ 30#include <zircon/syscalls.h> 31#endif 32 33#if defined(__APPLE__) 34extern "C" void sys_icache_invalidate(const void *Addr, size_t len); 35#else 36extern "C" void __clear_cache(void *, void*); 37#endif 38 39static int getPosixProtectionFlags(unsigned Flags) { 40 switch (Flags & llvm::sys::Memory::MF_RWE_MASK) { 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 | llvm::sys::Memory::MF_WRITE | 50 llvm::sys::Memory::MF_EXEC: 51 return PROT_READ | PROT_WRITE | PROT_EXEC; 52 case llvm::sys::Memory::MF_EXEC: 53#if (defined(__FreeBSD__) || defined(__POWERPC__) || defined (__ppc__) || \ 54 defined(_POWER) || defined(_ARCH_PPC)) 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 return PROT_READ | PROT_EXEC; 61#else 62 return PROT_EXEC; 63#endif 64 default: 65 llvm_unreachable("Illegal memory protection flag specified!"); 66 } 67 // Provide a default return value as required by some compilers. 68 return PROT_NONE; 69} 70 71namespace llvm { 72namespace sys { 73 74MemoryBlock 75Memory::allocateMappedMemory(size_t NumBytes, 76 const MemoryBlock *const NearBlock, 77 unsigned PFlags, 78 std::error_code &EC) { 79 EC = std::error_code(); 80 if (NumBytes == 0) 81 return MemoryBlock(); 82 83 // On platforms that have it, we can use MAP_ANON to get a memory-mapped 84 // page without file backing, but we need a fallback of opening /dev/zero 85 // for strictly POSIX platforms instead. 86 int fd; 87#if defined(MAP_ANON) 88 fd = -1; 89#else 90 fd = open("/dev/zero", O_RDWR); 91 if (fd == -1) { 92 EC = std::error_code(errno, std::generic_category()); 93 return MemoryBlock(); 94 } 95#endif 96 97 int MMFlags = MAP_PRIVATE; 98#if defined(MAP_ANON) 99 MMFlags |= MAP_ANON; 100#endif 101 int Protect = getPosixProtectionFlags(PFlags); 102 103#if defined(__NetBSD__) && defined(PROT_MPROTECT) 104 Protect |= PROT_MPROTECT(PROT_READ | PROT_WRITE | PROT_EXEC); 105#endif 106 107 // Use any near hint and the page size to set a page-aligned starting address 108 uintptr_t Start = NearBlock ? reinterpret_cast<uintptr_t>(NearBlock->base()) + 109 NearBlock->allocatedSize() : 0; 110 static const size_t PageSize = Process::getPageSizeEstimate(); 111 const size_t NumPages = (NumBytes+PageSize-1)/PageSize; 112 113 if (Start && Start % PageSize) 114 Start += PageSize - Start % PageSize; 115 116 // FIXME: Handle huge page requests (MF_HUGE_HINT). 117 void *Addr = ::mmap(reinterpret_cast<void *>(Start), PageSize*NumPages, Protect, 118 MMFlags, fd, 0); 119 if (Addr == MAP_FAILED) { 120 if (NearBlock) { //Try again without a near hint 121#if !defined(MAP_ANON) 122 close(fd); 123#endif 124 return allocateMappedMemory(NumBytes, nullptr, PFlags, EC); 125 } 126 127 EC = std::error_code(errno, std::generic_category()); 128#if !defined(MAP_ANON) 129 close(fd); 130#endif 131 return MemoryBlock(); 132 } 133 134#if !defined(MAP_ANON) 135 close(fd); 136#endif 137 138 MemoryBlock Result; 139 Result.Address = Addr; 140 Result.AllocatedSize = PageSize*NumPages; 141 Result.Flags = PFlags; 142 143 // Rely on protectMappedMemory to invalidate instruction cache. 144 if (PFlags & MF_EXEC) { 145 EC = Memory::protectMappedMemory (Result, PFlags); 146 if (EC != std::error_code()) 147 return MemoryBlock(); 148 } 149 150 return Result; 151} 152 153std::error_code 154Memory::releaseMappedMemory(MemoryBlock &M) { 155 if (M.Address == nullptr || M.AllocatedSize == 0) 156 return std::error_code(); 157 158 if (0 != ::munmap(M.Address, M.AllocatedSize)) 159 return std::error_code(errno, std::generic_category()); 160 161 M.Address = nullptr; 162 M.AllocatedSize = 0; 163 164 return std::error_code(); 165} 166 167std::error_code 168Memory::protectMappedMemory(const MemoryBlock &M, unsigned Flags) { 169 static const Align PageSize = Align(Process::getPageSizeEstimate()); 170 if (M.Address == nullptr || M.AllocatedSize == 0) 171 return std::error_code(); 172 173 if (!Flags) 174 return std::error_code(EINVAL, std::generic_category()); 175 176 int Protect = getPosixProtectionFlags(Flags); 177 uintptr_t Start = alignAddr((const uint8_t *)M.Address - PageSize.value() + 1, PageSize); 178 uintptr_t End = alignAddr((const uint8_t *)M.Address + M.AllocatedSize, PageSize); 179 180 bool InvalidateCache = (Flags & MF_EXEC); 181 182#if defined(__arm__) || defined(__aarch64__) 183 // Certain ARM implementations treat icache clear instruction as a memory read, 184 // and CPU segfaults on trying to clear cache on !PROT_READ page. Therefore we need 185 // to temporarily add PROT_READ for the sake of flushing the instruction caches. 186 if (InvalidateCache && !(Protect & PROT_READ)) { 187 int Result = ::mprotect((void *)Start, End - Start, Protect | PROT_READ); 188 if (Result != 0) 189 return std::error_code(errno, std::generic_category()); 190 191 Memory::InvalidateInstructionCache(M.Address, M.AllocatedSize); 192 InvalidateCache = false; 193 } 194#endif 195 196 int Result = ::mprotect((void *)Start, End - Start, Protect); 197 198 if (Result != 0) 199 return std::error_code(errno, std::generic_category()); 200 201 if (InvalidateCache) 202 Memory::InvalidateInstructionCache(M.Address, M.AllocatedSize); 203 204 return std::error_code(); 205} 206 207/// InvalidateInstructionCache - Before the JIT can run a block of code 208/// that has been emitted it must invalidate the instruction cache on some 209/// platforms. 210void Memory::InvalidateInstructionCache(const void *Addr, 211 size_t Len) { 212 213// icache invalidation for PPC and ARM. 214#if defined(__APPLE__) 215 216# if (defined(__POWERPC__) || defined (__ppc__) || \ 217 defined(_POWER) || defined(_ARCH_PPC) || defined(__arm__) || \ 218 defined(__arm64__)) 219 sys_icache_invalidate(const_cast<void *>(Addr), Len); 220# endif 221 222#elif defined(__Fuchsia__) 223 224 zx_status_t Status = zx_cache_flush(Addr, Len, ZX_CACHE_FLUSH_INSN); 225 assert(Status == ZX_OK && "cannot invalidate instruction cache"); 226 227#else 228 229# if (defined(__POWERPC__) || defined (__ppc__) || \ 230 defined(_POWER) || defined(_ARCH_PPC)) && defined(__GNUC__) 231 const size_t LineSize = 32; 232 233 const intptr_t Mask = ~(LineSize - 1); 234 const intptr_t StartLine = ((intptr_t) Addr) & Mask; 235 const intptr_t EndLine = ((intptr_t) Addr + Len + LineSize - 1) & Mask; 236 237 for (intptr_t Line = StartLine; Line < EndLine; Line += LineSize) 238 asm volatile("dcbf 0, %0" : : "r"(Line)); 239 asm volatile("sync"); 240 241 for (intptr_t Line = StartLine; Line < EndLine; Line += LineSize) 242 asm volatile("icbi 0, %0" : : "r"(Line)); 243 asm volatile("isync"); 244# elif (defined(__arm__) || defined(__aarch64__) || defined(__mips__)) && \ 245 defined(__GNUC__) 246 // FIXME: Can we safely always call this for __GNUC__ everywhere? 247 const char *Start = static_cast<const char *>(Addr); 248 const char *End = Start + Len; 249 __clear_cache(const_cast<char *>(Start), const_cast<char *>(End)); 250# endif 251 252#endif // end apple 253 254 ValgrindDiscardTranslations(Addr, Len); 255} 256 257} // namespace sys 258} // namespace llvm 259