src/llvm/include/llvm/ExecutionEngine/SectionMemoryManager.h

   1 //===- SectionMemoryManager.h - Memory manager for MCJIT/RtDyld -*- 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 contains the declaration of a section-based memory manager used by
  11 // the MCJIT execution engine and RuntimeDyld.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #ifndef LLVM_EXECUTIONENGINE_SECTIONMEMORYMANAGER_H
  16 #define LLVM_EXECUTIONENGINE_SECTIONMEMORYMANAGER_H
  17
  18 #include "llvm/ADT/SmallVector.h"
  19 #include "llvm/ExecutionEngine/RuntimeDyld.h"
  20 #include "llvm/Support/ErrorHandling.h"
  21 #include "llvm/Support/Memory.h"
  22
  23 namespace llvm {
  24 /// This is a simple memory manager which implements the methods called by
  25 /// the RuntimeDyld class to allocate memory for section-based loading of
  26 /// objects, usually those generated by the MCJIT execution engine.
  27 ///
  28 /// This memory manager allocates all section memory as read-write.  The
  29 /// RuntimeDyld will copy JITed section memory into these allocated blocks
  30 /// and perform any necessary linking and relocations.
  31 ///
  32 /// Any client using this memory manager MUST ensure that section-specific
  33 /// page permissions have been applied before attempting to execute functions
  34 /// in the JITed object.  Permissions can be applied either by calling
  35 /// MCJIT::finalizeObject or by calling SectionMemoryManager::finalizeMemory
  36 /// directly.  Clients of MCJIT should call MCJIT::finalizeObject.
  37 class SectionMemoryManager : public RTDyldMemoryManager {
  38   SectionMemoryManager(const SectionMemoryManager&) LLVM_DELETED_FUNCTION;
  39   void operator=(const SectionMemoryManager&) LLVM_DELETED_FUNCTION;
  40
  41 public:
  42   SectionMemoryManager() { }
  43   virtual ~SectionMemoryManager();
  44
  45   /// \brief Allocates a memory block of (at least) the given size suitable for
  46   /// executable code.
  47   ///
  48   /// The value of \p Alignment must be a power of two.  If \p Alignment is zero
  49   /// a default alignment of 16 will be used.
  50   uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment,
  51                                unsigned SectionID,
  52                                StringRef SectionName) override;
  53
  54   /// \brief Allocates a memory block of (at least) the given size suitable for
  55   /// executable code.
  56   ///
  57   /// The value of \p Alignment must be a power of two.  If \p Alignment is zero
  58   /// a default alignment of 16 will be used.
  59   uint8_t *allocateDataSection(uintptr_t Size, unsigned Alignment,
  60                                unsigned SectionID, StringRef SectionName,
  61                                bool isReadOnly) override;
  62
  63   /// \brief Update section-specific memory permissions and other attributes.
  64   ///
  65   /// This method is called when object loading is complete and section page
  66   /// permissions can be applied.  It is up to the memory manager implementation
  67   /// to decide whether or not to act on this method.  The memory manager will
  68   /// typically allocate all sections as read-write and then apply specific
  69   /// permissions when this method is called.  Code sections cannot be executed
  70   /// until this function has been called.  In addition, any cache coherency
  71   /// operations needed to reliably use the memory are also performed.
  72   ///
  73   /// \returns true if an error occurred, false otherwise.
  74   bool finalizeMemory(std::string *ErrMsg = nullptr) override;
  75
  76   /// \brief Invalidate instruction cache for code sections.
  77   ///
  78   /// Some platforms with separate data cache and instruction cache require
  79   /// explicit cache flush, otherwise JIT code manipulations (like resolved
  80   /// relocations) will get to the data cache but not to the instruction cache.
  81   ///
  82   /// This method is called from finalizeMemory.
  83   virtual void invalidateInstructionCache();
  84
  85 private:
  86   struct MemoryGroup {
  87       SmallVector<sys::MemoryBlock, 16> AllocatedMem;
  88       SmallVector<sys::MemoryBlock, 16> FreeMem;
  89       sys::MemoryBlock Near;
  90   };
  91
  92   uint8_t *allocateSection(MemoryGroup &MemGroup, uintptr_t Size,
  93                            unsigned Alignment);
  94
  95   std::error_code applyMemoryGroupPermissions(MemoryGroup &MemGroup,
  96                                               unsigned Permissions);
  97
  98   MemoryGroup CodeMem;
  99   MemoryGroup RWDataMem;
 100   MemoryGroup RODataMem;
 101 };
 102
 103 }
 104
 105 #endif // LLVM_EXECUTION_ENGINE_SECTION_MEMORY_MANAGER_H
 106