LCOV - code coverage report
Current view: top level - lib/Support/Unix - Memory.inc (source / functions) Hit Total Coverage
Test: llvm-toolchain.info Lines: 45 57 78.9 %
Date: 2018-06-17 00:07:59 Functions: 4 4 100.0 %
Legend: Lines: hit not hit

          Line data    Source code
       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__)
      41             : extern "C" void sys_icache_invalidate(const void *Addr, size_t len);
      42             : #else
      43             : extern "C" void __clear_cache(void *, void*);
      44             : #endif
      45             : 
      46             : namespace {
      47             : 
      48             : int getPosixProtectionFlags(unsigned Flags) {
      49        2066 :   switch (Flags) {
      50             :   case llvm::sys::Memory::MF_READ:
      51             :     return PROT_READ;
      52          22 :   case llvm::sys::Memory::MF_WRITE:
      53             :     return PROT_WRITE;
      54        1083 :   case llvm::sys::Memory::MF_READ|llvm::sys::Memory::MF_WRITE:
      55             :     return PROT_READ | PROT_WRITE;
      56         815 :   case llvm::sys::Memory::MF_READ|llvm::sys::Memory::MF_EXEC:
      57             :     return PROT_READ | PROT_EXEC;
      58          66 :   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          44 :   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           0 :   default:
      75           0 :     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             : 
      83             : namespace llvm {
      84             : namespace sys {
      85             : 
      86             : MemoryBlock
      87        1172 : Memory::allocateMappedMemory(size_t NumBytes,
      88             :                              const MemoryBlock *const NearBlock,
      89             :                              unsigned PFlags,
      90             :                              std::error_code &EC) {
      91        1172 :   EC = std::error_code();
      92        1172 :   if (NumBytes == 0)
      93           0 :     return MemoryBlock();
      94             : 
      95        1172 :   static const size_t PageSize = Process::getPageSize();
      96        1172 :   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        1965 :   uintptr_t Start = NearBlock ? reinterpret_cast<uintptr_t>(NearBlock->base()) +
     116         793 :                                       NearBlock->size() : 0;
     117         793 :   if (Start && Start % PageSize)
     118          24 :     Start += PageSize - Start % PageSize;
     119             : 
     120        1172 :   void *Addr = ::mmap(reinterpret_cast<void*>(Start), PageSize*NumPages,
     121        1172 :                       Protect, MMFlags, fd, 0);
     122        1172 :   if (Addr == MAP_FAILED) {
     123           0 :     if (NearBlock) //Try again without a near hint
     124           0 :       return allocateMappedMemory(NumBytes, nullptr, PFlags, EC);
     125             : 
     126           0 :     EC = std::error_code(errno, std::generic_category());
     127           0 :     return MemoryBlock();
     128             :   }
     129             : 
     130             :   MemoryBlock Result;
     131        1172 :   Result.Address = Addr;
     132        1172 :   Result.Size = NumPages*PageSize;
     133             : 
     134             :   // Rely on protectMappedMemory to invalidate instruction cache.
     135        1172 :   if (PFlags & MF_EXEC) {
     136          71 :     EC = Memory::protectMappedMemory (Result, PFlags);
     137             :     if (EC != std::error_code())
     138           0 :       return MemoryBlock();
     139             :   }
     140             : 
     141        1172 :   return Result;
     142             : }
     143             : 
     144             : std::error_code
     145         740 : Memory::releaseMappedMemory(MemoryBlock &M) {
     146         740 :   if (M.Address == nullptr || M.Size == 0)
     147          87 :     return std::error_code();
     148             : 
     149         653 :   if (0 != ::munmap(M.Address, M.Size))
     150           0 :     return std::error_code(errno, std::generic_category());
     151             : 
     152         653 :   M.Address = nullptr;
     153         653 :   M.Size = 0;
     154             : 
     155         653 :   return std::error_code();
     156             : }
     157             : 
     158             : std::error_code
     159         894 : Memory::protectMappedMemory(const MemoryBlock &M, unsigned Flags) {
     160         894 :   static const size_t PageSize = Process::getPageSize();
     161         894 :   if (M.Address == nullptr || M.Size == 0)
     162           0 :     return std::error_code();
     163             : 
     164         894 :   if (!Flags)
     165           0 :     return std::error_code(EINVAL, std::generic_category());
     166             : 
     167             :   int Protect = getPosixProtectionFlags(Flags);
     168         894 :   uintptr_t Start = alignAddr((uint8_t *)M.Address - PageSize + 1, PageSize);
     169         894 :   uintptr_t End = alignAddr((uint8_t *)M.Address + M.Size, PageSize);
     170             : 
     171         894 :   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         894 :   int Result = ::mprotect((void *)Start, End - Start, Protect);
     188             : 
     189         894 :   if (Result != 0)
     190           0 :     return std::error_code(errno, std::generic_category());
     191             : 
     192         894 :   if (InvalidateCache)
     193         854 :     Memory::InvalidateInstructionCache(M.Address, M.Size);
     194             : 
     195         894 :   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.
     201         854 : void 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             :   __builtin___clear_cache(const_cast<char *>(Start), const_cast<char *>(End));
     241             : #  endif
     242             : 
     243             : #endif  // end apple
     244             : 
     245         854 :   ValgrindDiscardTranslations(Addr, Len);
     246         854 : }
     247             : 
     248             : } // namespace sys
     249             : } // namespace llvm

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