1 // Copyright 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 "base/trace_event/heap_profiler_allocation_register.h"
6
7 #include <stddef.h>
8 #include <sys/mman.h>
9 #include <unistd.h>
10
11 #include "base/bits.h"
12 #include "base/logging.h"
13 #include "base/process/process_metrics.h"
14
15 #ifndef MAP_ANONYMOUS
16 #define MAP_ANONYMOUS MAP_ANON
17 #endif
18
19 namespace base {
20 namespace trace_event {
21 namespace internal {
22
23 namespace {
GetGuardSize()24 size_t GetGuardSize() {
25 return GetPageSize();
26 }
27 }
28
AllocateGuardedVirtualMemory(size_t size)29 void* AllocateGuardedVirtualMemory(size_t size) {
30 size = bits::Align(size, GetPageSize());
31
32 // Add space for a guard page at the end.
33 size_t map_size = size + GetGuardSize();
34
35 void* addr = mmap(nullptr, map_size, PROT_READ | PROT_WRITE,
36 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
37
38 PCHECK(addr != MAP_FAILED);
39
40 // Mark the last page of the allocated address space as inaccessible
41 // (PROT_NONE). The read/write accessible space is still at least |min_size|
42 // bytes.
43 void* guard_addr =
44 reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(addr) + size);
45 int result = mprotect(guard_addr, GetGuardSize(), PROT_NONE);
46 PCHECK(result == 0);
47
48 return addr;
49 }
50
FreeGuardedVirtualMemory(void * address,size_t allocated_size)51 void FreeGuardedVirtualMemory(void* address, size_t allocated_size) {
52 size_t size = bits::Align(allocated_size, GetPageSize()) + GetGuardSize();
53 munmap(address, size);
54 }
55
56 } // namespace internal
57 } // namespace trace_event
58 } // namespace base
59