mozglue/misc/MmapFaultHandler.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #ifndef MmapFaultHandler_h_
   7 #define MmapFaultHandler_h_
   8
   9 #if defined(XP_WIN)
  10 // Windows
  11
  12 #  ifdef HAVE_SEH_EXCEPTIONS
  13 #    define MMAP_FAULT_HANDLER_BEGIN_HANDLE(fd) __try {
  14 #    define MMAP_FAULT_HANDLER_BEGIN_BUFFER(buf, bufLen) __try {
  15 #    define MMAP_FAULT_HANDLER_CATCH(retval)                  \
  16       }                                                       \
  17       __except (GetExceptionCode() == EXCEPTION_IN_PAGE_ERROR \
  18                     ? EXCEPTION_EXECUTE_HANDLER               \
  19                     : EXCEPTION_CONTINUE_SEARCH) {            \
  20         NS_WARNING("unexpected EXCEPTION_IN_PAGE_ERROR");     \
  21         return retval;                                        \
  22       }
  23 #  else
  24 #    define MMAP_FAULT_HANDLER_BEGIN_HANDLE(fd) {
  25 #    define MMAP_FAULT_HANDLER_BEGIN_BUFFER(buf, bufLen) {
  26 #    define MMAP_FAULT_HANDLER_CATCH(retval) }
  27 #  endif
  28
  29 #elif defined(XP_DARWIN)
  30 // MacOS
  31
  32 #  define MMAP_FAULT_HANDLER_BEGIN_HANDLE(fd) {
  33 #  define MMAP_FAULT_HANDLER_BEGIN_BUFFER(buf, bufLen) {
  34 #  define MMAP_FAULT_HANDLER_CATCH(retval) }
  35
  36 #elif defined(__wasi__)
  37
  38 #  define MMAP_FAULT_HANDLER_BEGIN_HANDLE(fd) {
  39 #  define MMAP_FAULT_HANDLER_BEGIN_BUFFER(buf, bufLen) {
  40 #  define MMAP_FAULT_HANDLER_CATCH(retval) }
  41
  42 #else
  43 // Linux
  44
  45 #  include "mozilla/Attributes.h"
  46 #  include "mozilla/Types.h"
  47 #  include <stdint.h>
  48 #  include <setjmp.h>
  49
  50 class MOZ_RAII MmapAccessScope {
  51  public:
  52   MFBT_API MmapAccessScope(void* aBuf, uint32_t aBufLen,
  53                            const char* aFilename = nullptr);
  54   MFBT_API ~MmapAccessScope();
  55
  56   MmapAccessScope(const MmapAccessScope&) = delete;
  57   MmapAccessScope& operator=(const MmapAccessScope&) = delete;
  58
  59   void SetThreadLocalScope();
  60   bool IsInsideBuffer(void* aPtr);
  61   void CrashWithInfo(void* aPtr);
  62
  63   // sigsetjmp cannot be called from a method that returns before calling
  64   // siglongjmp, so the macro must call sigsetjmp directly and mJmpBuf must be
  65   // public.
  66   sigjmp_buf mJmpBuf;
  67
  68  private:
  69   void* mBuf;
  70   const char* mFilename;
  71   uint32_t mBufLen;
  72   MmapAccessScope* mPreviousScope;
  73 };
  74
  75 // Gets around warnings for null-checking in a macro.
  76 template <typename T>
  77 inline bool ValidFD(T fd) {
  78   return !!fd;
  79 }
  80
  81 #  define MMAP_FAULT_HANDLER_BEGIN_HANDLE(fd)                  \
  82     {                                                          \
  83       void* mmapScopeBuf = nullptr;                            \
  84       nsCString mmapScopeFilename;                             \
  85       uint32_t mmapScopeBufLen = 0;                            \
  86       if (ValidFD(fd) && fd->mMap) {                           \
  87         mmapScopeBuf = (void*)fd->mFileStart;                  \
  88         mmapScopeBufLen = fd->mTotalLen;                       \
  89       }                                                        \
  90       if (ValidFD(fd) && fd->mFile) {                          \
  91         nsCOMPtr<nsIFile> file = fd->mFile.GetBaseFile();      \
  92         file->GetNativeLeafName(mmapScopeFilename);            \
  93       }                                                        \
  94       MmapAccessScope mmapScope(mmapScopeBuf, mmapScopeBufLen, \
  95                                 mmapScopeFilename.get());      \
  96       if (sigsetjmp(mmapScope.mJmpBuf, 0) == 0) {
  97 #  define MMAP_FAULT_HANDLER_BEGIN_BUFFER(buf, bufLen)   \
  98     {                                                    \
  99       MmapAccessScope mmapScope((void*)(buf), (bufLen)); \
 100       if (sigsetjmp(mmapScope.mJmpBuf, 0) == 0) {
 101 #  define MMAP_FAULT_HANDLER_CATCH(retval)                       \
 102     }                                                            \
 103     else {                                                       \
 104       NS_WARNING("SIGBUS received when accessing mmapped file"); \
 105       return retval;                                             \
 106     }                                                            \
 107     }
 108
 109 #endif
 110
 111 #endif