1//===-- utilities_posix.cpp -------------------------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "gwp_asan/definitions.h"
10#include "gwp_asan/utilities.h"
11
12#include <assert.h>
13
14#ifdef __BIONIC__
15#include <stdlib.h>
16extern "C" GWP_ASAN_WEAK void android_set_abort_message(const char *);
17#else // __BIONIC__
18#include <stdio.h>
19#endif
20
21namespace gwp_asan {
22
23#ifdef __BIONIC__
24void Check(bool Condition, const char *Message) {
25  if (Condition)
26    return;
27  if (&android_set_abort_message != nullptr)
28    android_set_abort_message(Message);
29  abort();
30}
31#else  // __BIONIC__
32void Check(bool Condition, const char *Message) {
33  if (Condition)
34    return;
35  fprintf(stderr, "%s", Message);
36  __builtin_trap();
37}
38#endif // __BIONIC__
39
40// See `bionic/tests/malloc_test.cpp` in the Android source for documentation
41// regarding their alignment guarantees. We always round up to the closest
42// 8-byte window. As GWP-ASan's malloc(X) can always get exactly an X-sized
43// allocation, an allocation that rounds up to 16-bytes will always be given a
44// 16-byte aligned allocation.
45static size_t alignBionic(size_t RealAllocationSize) {
46  if (RealAllocationSize % 8 == 0)
47    return RealAllocationSize;
48  return RealAllocationSize + 8 - (RealAllocationSize % 8);
49}
50
51static size_t alignPowerOfTwo(size_t RealAllocationSize) {
52  if (RealAllocationSize <= 2)
53    return RealAllocationSize;
54  if (RealAllocationSize <= 4)
55    return 4;
56  if (RealAllocationSize <= 8)
57    return 8;
58  if (RealAllocationSize % 16 == 0)
59    return RealAllocationSize;
60  return RealAllocationSize + 16 - (RealAllocationSize % 16);
61}
62
63#ifdef __BIONIC__
64static constexpr AlignmentStrategy PlatformDefaultAlignment =
65    AlignmentStrategy::BIONIC;
66#else  // __BIONIC__
67static constexpr AlignmentStrategy PlatformDefaultAlignment =
68    AlignmentStrategy::POWER_OF_TWO;
69#endif // __BIONIC__
70
71size_t rightAlignedAllocationSize(size_t RealAllocationSize,
72                                  AlignmentStrategy Align) {
73  assert(RealAllocationSize > 0);
74  if (Align == AlignmentStrategy::DEFAULT)
75    Align = PlatformDefaultAlignment;
76
77  switch (Align) {
78  case AlignmentStrategy::BIONIC:
79    return alignBionic(RealAllocationSize);
80  case AlignmentStrategy::POWER_OF_TWO:
81    return alignPowerOfTwo(RealAllocationSize);
82  case AlignmentStrategy::PERFECT:
83    return RealAllocationSize;
84  case AlignmentStrategy::DEFAULT:
85    __builtin_unreachable();
86  }
87  __builtin_unreachable();
88}
89
90} // namespace gwp_asan
91