[Tracing] Add allocation register for heap profiling

base/trace_event/memory_profiler_allocation_register_linux.cc

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/trace_event/memory_profiler_allocation_register.h"
+
+#include <sys/mman.h>
+#include <unistd.h>
+
+#include "base/basictypes.h"
+#include "base/logging.h"
+
+namespace base {
+namespace trace_event {
+
+size_t GetSystemPageSize() {
+  return sysconf(_SC_PAGE_SIZE);
+}
+
+void* AllocateVirtualMemory(size_t min_size, VirtualMemoryGuard guard) {
+  size_t size = RoundUpToPageSize(min_size);
+  size_t map_size = size;
+
+  if (guard == VirtualMemoryGuard::kGuardPageAfter)
+    map_size += GetSystemPageSize();
+
+  void* addr = mmap(nullptr, map_size, PROT_READ | PROT_WRITE,
+                    MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+
+  PCHECK(addr != MAP_FAILED);
+
+  // If there is a guard page after, mark the last page of the allocated
+  // address space as inaccessible (PROT_NONE). The read/write accessible space
+  // is still at least |min_size| bytes.
+  if (guard == VirtualMemoryGuard::kGuardPageAfter) {
+    void* guard_addr = static_cast<void*>(static_cast<uint8_t*>(addr) + size);
+    size_t guard_size = map_size - size;
+    int result = mprotect(guard_addr, guard_size, PROT_NONE);
+    PCHECK(result == 0);
+  }
+
+  return addr;
+}
+
+void FreeVirtualMemory(void* address,
+                       size_t allocated_min_size,
+                       VirtualMemoryGuard allocated_guard) {
+  size_t size = RoundUpToPageSize(allocated_min_size);
+
+  if (allocated_guard == VirtualMemoryGuard::kGuardPageAfter)
+    size += GetSystemPageSize();
+
+  munmap(address, size);
+}
+
+}  // namespace trace_event
+}  // namespace base