1 //===-- hwasan_poisoning.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 // This file is a part of HWAddressSanitizer.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "hwasan_poisoning.h"
14 
15 #include "hwasan_mapping.h"
16 #include "interception/interception.h"
17 #include "sanitizer_common/sanitizer_common.h"
18 #include "sanitizer_common/sanitizer_linux.h"
19 
20 namespace __hwasan {
21 
TagMemoryAligned(uptr p,usize size,tag_t tag)22 uptr TagMemoryAligned(uptr p, usize size, tag_t tag) {
23   CHECK(IsAligned(p, kShadowAlignment));
24   CHECK(IsAligned(size, kShadowAlignment));
25   uptr shadow_start = MemToShadow(p);
26   uptr shadow_size = MemToShadowSize(size);
27 
28   uptr page_size = GetPageSizeCached();
29   uptr page_start = RoundUpTo(shadow_start, page_size);
30   uptr page_end = RoundDownTo(shadow_start + shadow_size, page_size);
31   uptr threshold = common_flags()->clear_shadow_mmap_threshold;
32   if (SANITIZER_LINUX &&
33       UNLIKELY(page_end >= page_start + threshold && tag == 0)) {
34     internal_memset((void *)shadow_start, tag, page_start - shadow_start);
35     internal_memset((void *)page_end, tag,
36                     shadow_start + shadow_size - page_end);
37     // For an anonymous private mapping MADV_DONTNEED will return a zero page on
38     // Linux.
39     ReleaseMemoryPagesToOSAndZeroFill(page_start, page_end);
40   } else {
41     internal_memset((void *)shadow_start, tag, shadow_size);
42   }
43   return AddTagToPointer(p, tag);
44 }
45 
TagMemory(uptr p,usize size,tag_t tag)46 uptr TagMemory(uptr p, usize size, tag_t tag) {
47   uptr start = RoundDownTo(p, kShadowAlignment);
48   uptr end = RoundUpTo(p + size, kShadowAlignment);
49   return TagMemoryAligned(start, end - start, tag);
50 }
51 
52 }  // namespace __hwasan
53