chrome/app/chrome_exe_load_config_win.cc

   1 // Copyright (c) 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include <windows.h>
   6
   7 // The whole object of this file is to define |_load_config_used| which
   8 // is a weakly-linked symbol that the linker knows about. The crt defines
   9 // it as well it but this one will be used if present.
  10 //
  11 // The _load_config_used appears in the exe as a special member of the PE
  12 // image format: the load config directory. This structure controls
  13 // global parameters which are hard or impossible to set otherwise. This
  14 // MSDN page https://goo.gl/zsGeVY documents some of the members.
  15 //
  16 // When making a changes to this stucture the only practical way to make
  17 // sure they are honored is to run dumpbin.exe <exe-file> /loadconfig
  18 // and inspect the results.
  19
  20 #if defined(_WIN64)
  21 typedef struct {
  22   DWORD      Size;
  23   DWORD      TimeDateStamp;
  24   WORD       MajorVersion;
  25   WORD       MinorVersion;
  26   DWORD      GlobalFlagsClear;
  27   DWORD      GlobalFlagsSet;
  28   DWORD      CriticalSectionDefaultTimeout;
  29   ULONGLONG  DeCommitFreeBlockThreshold;
  30   ULONGLONG  DeCommitTotalFreeThreshold;
  31   ULONGLONG  LockPrefixTable;
  32   ULONGLONG  MaximumAllocationSize;
  33   ULONGLONG  VirtualMemoryThreshold;
  34   ULONGLONG  ProcessAffinityMask;
  35   DWORD      ProcessHeapFlags;
  36   WORD       CSDVersion;
  37   WORD       Reserved1;
  38   ULONGLONG  EditList;
  39   ULONGLONG  SecurityCookie;
  40   ULONGLONG  SEHandlerTable;
  41   ULONGLONG  SEHandlerCount;
  42 } IMAGE_LOAD_CONFIG_DIRECTORY64_2;
  43 typedef IMAGE_LOAD_CONFIG_DIRECTORY64_2 IMAGE_LOAD_CONFIG_DIRECTORY_2;
  44 #else
  45 typedef struct {
  46   DWORD       Size;
  47   DWORD       TimeDateStamp;
  48   WORD        MajorVersion;
  49   WORD        MinorVersion;
  50   DWORD       GlobalFlagsClear;
  51   DWORD       GlobalFlagsSet;
  52   DWORD       CriticalSectionDefaultTimeout;
  53   DWORD       DeCommitFreeBlockThreshold;
  54   DWORD       DeCommitTotalFreeThreshold;
  55   DWORD       LockPrefixTable;
  56   DWORD       MaximumAllocationSize;
  57   DWORD       VirtualMemoryThreshold;
  58   DWORD       ProcessHeapFlags;
  59   DWORD       ProcessAffinityMask;
  60   WORD        CSDVersion;
  61   WORD        Reserved1;
  62   DWORD       EditList;
  63   PUINT_PTR   SecurityCookie;
  64   PVOID       *SEHandlerTable;
  65   DWORD       SEHandlerCount;
  66 } IMAGE_LOAD_CONFIG_DIRECTORY32_2;
  67 typedef IMAGE_LOAD_CONFIG_DIRECTORY32_2 IMAGE_LOAD_CONFIG_DIRECTORY_2;
  68 #endif
  69
  70 // What follows, except as indicated is verbatim (including casts) from
  71 // <visual studio path>\VC\crt\src\intel\loadcfg.c. The default values
  72 // are all 0 except for the last 3 members. See
  73 // https://msdn.microsoft.com/en-us/library/9a89h429.aspx for an
  74 // explanation of these members.
  75 extern "C" UINT_PTR __security_cookie;
  76 extern "C" PVOID __safe_se_handler_table[];
  77 extern "C" BYTE __safe_se_handler_count;
  78
  79 // DeCommitTotalFreeThreshold: increase the decomit free threshold for
  80 // the process heap, which is documented as "The size of the minimum
  81 // total memory that must be freed in the process heap before it is
  82 // freed (de-committed) in bytes".
  83 //
  84 // Set at 2 MiB what this does is prevent a lot of VirtualFree plus the
  85 // following VirtualAlloc because the default value makes the heap too
  86 // conservative on the ammount of memory it keeps for future allocations.
  87
  88 extern "C"
  89 const IMAGE_LOAD_CONFIG_DIRECTORY_2  _load_config_used = {
  90   sizeof(IMAGE_LOAD_CONFIG_DIRECTORY_2),
  91   0,  // TimeDateStamp.
  92   0,  // MajorVersion.
  93   0,  // MinorVersion.
  94   0,  // GlobalFlagsClear.
  95   0,  // GlobalFlagsSet.
  96   0,  // CriticalSectionDefaultTimeout.
  97   0,  // DeCommitFreeBlockThreshold.
  98   2 * 1024 * 1024,  // DeCommitTotalFreeThreshold.
  99   0,  // LockPrefixTable.
 100   0,  // MaximumAllocationSize.
 101   0,  // VirtualMemoryThreshold.
 102   0,  // ProcessHeapFlags.
 103   0,  // ProcessAffinityMask.
 104   0,  // CSDVersion.
 105   0,  // Reserved1.
 106   0 , // EditList.
 107 #ifdef _WIN64
 108   (ULONGLONG)&__security_cookie,
 109 #else
 110   &__security_cookie,
 111   __safe_se_handler_table,
 112   (DWORD)(DWORD_PTR)&__safe_se_handler_count
 113 #endif
 114 };