[NOT TO COMMIT!] Merge Chromium-specific changes in tcmalloc thru. the original gperftools r136.

third_party/tcmalloc/chromium/src/windows/port.cc

 /* Copyright (c) 2007, Google Inc.
  * All rights reserved.
  * 
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  * 
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 43 matching lines @@
   static int pagesize = 0;
   if (pagesize == 0) {
     SYSTEM_INFO system_info;
     GetSystemInfo(&system_info);
     pagesize = std::max(system_info.dwPageSize,
                         system_info.dwAllocationGranularity);
   }
   return pagesize;
 }
 
-extern "C" PERFTOOLS_DLL_DECL void* __sbrk(ptrdiff_t increment) {
+extern "C" PERFTOOLS_DLL_DECL void* __sbrk(std::ptrdiff_t increment) {
   LOG(FATAL, "Windows doesn't implement sbrk!\n");
   return NULL;
 }
 
 // We need to write to 'stderr' without having windows allocate memory.
 // The safest way is via a low-level call like WriteConsoleA().  But
 // even then we need to be sure to print in small bursts so as to not
 // require memory allocation.
 extern "C" PERFTOOLS_DLL_DECL void WriteToStderr(const char* buf, int len) {
   // Looks like windows allocates for writes of >80 bytes
@@ skipping 72 matching lines @@
   }
 }
 
 #ifdef _MSC_VER
 
 // extern "C" suppresses C++ name mangling so we know the symbol names
 // for the linker /INCLUDE:symbol pragmas above.
 extern "C" {
 // This tells the linker to run these functions.
 #pragma data_seg(push, old_seg)
-#pragma data_seg(".CRT$XLB")
+  // Use CRT$XLY instead of CRT$XLB to ensure we're called LATER in sequence.
+#pragma data_seg(".CRT$XLY")
 void (NTAPI *p_thread_callback_tcmalloc)(
     HINSTANCE h, DWORD dwReason, PVOID pv) = on_tls_callback;
 #pragma data_seg(".CRT$XTU")
 int (*p_process_term_tcmalloc)(void) = on_process_term;
 #pragma data_seg(pop, old_seg)
 }  // extern "C"
 
 #else  // #ifdef _MSC_VER  [probably msys/mingw]
 
 // We have to try the DllMain solution here, because we can't use the
@@ skipping 52 matching lines @@
 
 // This is mostly like MmapSysAllocator::Alloc, except it does these weird
 // munmap's in the middle of the page, which is forbidden in windows.
 extern void* TCMalloc_SystemAlloc(size_t size, size_t *actual_size,
                                   size_t alignment) {
   // Align on the pagesize boundary
   const int pagesize = getpagesize();
   if (alignment < pagesize) alignment = pagesize;
   size = ((size + alignment - 1) / alignment) * alignment;
 
-  // Safest is to make actual_size same as input-size.
+  // Report the total number of bytes the OS actually delivered.  This might be
+  // greater than |size| because of alignment concerns.  The full size is
+  // necessary so that adjacent spans can be coalesced.
+  // TODO(antonm): proper processing of alignments
+  // in actual_size and decommitting.
   if (actual_size) {
     *actual_size = size;
   }
 
-  // Ask for extra memory if alignment > pagesize
-  size_t extra = 0;
-  if (alignment > pagesize) {
-    extra = alignment - pagesize;
-  }
+  // We currently do not support alignments larger than the pagesize or
+  // alignments that are not multiples of the pagesize after being floored.
+  // If this ability is needed it can be done by the caller (assuming it knows
+  // the page size).
+  assert(alignment <= pagesize);
 
-  void* result = VirtualAlloc(0, size + extra,
+  void* result = VirtualAlloc(0, size,
                               MEM_COMMIT|MEM_RESERVE, PAGE_READWRITE);
   if (result == NULL)
     return NULL;
 
-  // Adjust the return memory so it is aligned
-  uintptr_t ptr = reinterpret_cast<uintptr_t>(result);
-  size_t adjust = 0;
-  if ((ptr & (alignment - 1)) != 0) {
-    adjust = alignment - (ptr & (alignment - 1));
+  // If the result is not aligned memory fragmentation will result which can
+  // lead to pathological memory use.
+  assert((reinterpret_cast<uintptr_t>(result) & (alignment - 1)) == 0);
+
+  return result;
+}
+
+size_t TCMalloc_SystemAddGuard(void* start, size_t size) {
+  static size_t pagesize = 0;
+  if (pagesize == 0) {
+    SYSTEM_INFO system_info;
+    GetSystemInfo(&system_info);
+    pagesize = system_info.dwPageSize;
   }
 
-  ptr += adjust;
-  return reinterpret_cast<void*>(ptr);
+  // We know that TCMalloc_SystemAlloc will give us a correct page alignment
+  // regardless, so we can just assert to detect erroneous callers.
+  assert(reinterpret_cast<size_t>(start) % pagesize == 0);
+
+  // Add a guard page to catch metadata corruption. We're using the
+  // PAGE_GUARD flag rather than NO_ACCESS because we want the unique
+  // exception in crash reports.
+  DWORD permissions = 0;
+  if (size > pagesize &&
+      VirtualProtect(start, pagesize, PAGE_READONLY | PAGE_GUARD,
+                     &permissions)) {
+    return pagesize;
+  }
+
+  return 0;
 }
 
 void TCMalloc_SystemRelease(void* start, size_t length) {
-  // TODO(csilvers): should I be calling VirtualFree here?
+  if (VirtualFree(start, length, MEM_DECOMMIT))
+    return;
+
+  // The decommit may fail if the memory region consists of allocations
+  // from more than one call to VirtualAlloc.  In this case, fall back to
+  // using VirtualQuery to retrieve the allocation boundaries and decommit
+  // them each individually.
+
+  char* ptr = static_cast<char*>(start);
+  char* end = ptr + length;
+  MEMORY_BASIC_INFORMATION info;
+  while (ptr < end) {
+    size_t resultSize = VirtualQuery(ptr, &info, sizeof(info));
+    assert(resultSize == sizeof(info));
+    size_t decommitSize = std::min<size_t>(info.RegionSize, end - ptr);
+    BOOL success = VirtualFree(ptr, decommitSize, MEM_DECOMMIT);
+    assert(success == TRUE);
+    ptr += decommitSize;
+  }
+}
+
+void TCMalloc_SystemCommit(void* start, size_t length) {
+  if (VirtualAlloc(start, length, MEM_COMMIT, PAGE_READWRITE) == start)
+    return;
+
+  // The commit may fail if the memory region consists of allocations
+  // from more than one call to VirtualAlloc.  In this case, fall back to
+  // using VirtualQuery to retrieve the allocation boundaries and commit them
+  // each individually.
+
+  char* ptr = static_cast<char*>(start);
+  char* end = ptr + length;
+  MEMORY_BASIC_INFORMATION info;
+  while (ptr < end) {
+    size_t resultSize = VirtualQuery(ptr, &info, sizeof(info));
+    assert(resultSize == sizeof(info));
+
+    size_t commitSize = std::min<size_t>(info.RegionSize, end - ptr);
+    void* newAddress = VirtualAlloc(ptr, commitSize, MEM_COMMIT,
+                                    PAGE_READWRITE);
+    assert(newAddress == ptr);
+    ptr += commitSize;
+  }
 }
 
 bool RegisterSystemAllocator(SysAllocator *allocator, int priority) {
   return false;   // we don't allow registration on windows, right now
 }
 
 void DumpSystemAllocatorStats(TCMalloc_Printer* printer) {
   // We don't dump stats on windows, right now
 }
 
@@ skipping 16 matching lines @@
       if ((strlen(fname) >= prefix_length) &&
           (memcmp(fname, prefix, prefix_length) == 0)) {
         RAW_VLOG(0, "Removing old heap profile %s\n", fname);
         // TODO(csilvers): we really need to unlink dirname + fname
         _unlink(fname);
       }
     } while (FindNextFileA(hFind, &found) != FALSE);  // A is for Ansi
     FindClose(hFind);
   }
 }