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1//===-- tsan_platform_posix.cpp -------------------------------------------===//
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 ThreadSanitizer (TSan), a race detector.
10//
11// POSIX-specific code.
12//===----------------------------------------------------------------------===//
13
14#include "sanitizer_common/sanitizer_platform.h"
15#if SANITIZER_POSIX
16
17# include <dlfcn.h>
18
19# include "sanitizer_common/sanitizer_common.h"
20# include "sanitizer_common/sanitizer_errno.h"
21# include "sanitizer_common/sanitizer_libc.h"
22# include "sanitizer_common/sanitizer_procmaps.h"
23# include "tsan_platform.h"
24# include "tsan_rtl.h"
25
26namespace __tsan {
27
28static const char kShadowMemoryMappingWarning[] =
29 "FATAL: %s can not madvise shadow region [%zx, %zx] with %s (errno: %d)\n";
30static const char kShadowMemoryMappingHint[] =
31 "HINT: if %s is not supported in your environment, you may set "
32 "TSAN_OPTIONS=%s=0\n";
33
34# if !SANITIZER_GO
35void DontDumpShadow(uptr addr, uptr size) {
36 if (common_flags()->use_madv_dontdump)
37 if (!DontDumpShadowMemory(addr, size)) {
38 Printf(kShadowMemoryMappingWarning, SanitizerToolName, addr, addr + size,
39 "MADV_DONTDUMP", errno);
40 Printf(kShadowMemoryMappingHint, "MADV_DONTDUMP", "use_madv_dontdump");
41 Die();
42 }
43}
44
45void InitializeShadowMemory() {
46 // Map memory shadow.
47 if (!MmapFixedSuperNoReserve(ShadowBeg(), ShadowEnd() - ShadowBeg(),
48 "shadow")) {
49 Printf("FATAL: ThreadSanitizer can not mmap the shadow memory\n");
50 Printf("FATAL: Make sure to compile with -fPIE and to link with -pie.\n");
51 Die();
52 }
53 // This memory range is used for thread stacks and large user mmaps.
54 // Frequently a thread uses only a small part of stack and similarly
55 // a program uses a small part of large mmap. On some programs
56 // we see 20% memory usage reduction without huge pages for this range.
57 DontDumpShadow(ShadowBeg(), ShadowEnd() - ShadowBeg());
58 DPrintf("memory shadow: %zx-%zx (%zuGB)\n",
59 ShadowBeg(), ShadowEnd(),
60 (ShadowEnd() - ShadowBeg()) >> 30);
61
62 // Map meta shadow.
63 const uptr meta = MetaShadowBeg();
64 const uptr meta_size = MetaShadowEnd() - meta;
65 if (!MmapFixedSuperNoReserve(meta, meta_size, "meta shadow")) {
66 Printf("FATAL: ThreadSanitizer can not mmap the shadow memory\n");
67 Printf("FATAL: Make sure to compile with -fPIE and to link with -pie.\n");
68 Die();
69 }
70 DontDumpShadow(meta, meta_size);
71 DPrintf("meta shadow: %zx-%zx (%zuGB)\n",
72 meta, meta + meta_size, meta_size >> 30);
73
74 InitializeShadowMemoryPlatform();
75
76 on_initialize = reinterpret_cast<void (*)(void)>(
77 dlsym(RTLD_DEFAULT, "__tsan_on_initialize"));
78 on_finalize =
79 reinterpret_cast<int (*)(int)>(dlsym(RTLD_DEFAULT, "__tsan_on_finalize"));
80}
81
82static bool TryProtectRange(uptr beg, uptr end) {
83 CHECK_LE(beg, end);
84 if (beg == end)
85 return true;
86 return beg == (uptr)MmapFixedNoAccess(beg, end - beg);
87}
88
89static void ProtectRange(uptr beg, uptr end) {
90 if (!TryProtectRange(beg, end)) {
91 Printf("FATAL: ThreadSanitizer can not protect [%zx,%zx]\n", beg, end);
92 Printf("FATAL: Make sure you are not using unlimited stack\n");
93 Die();
94 }
95}
96
97// CheckAndProtect will check if the memory layout is compatible with TSan.
98// Optionally (if 'protect' is true), it will set the memory regions between
99// app memory to be inaccessible.
100// 'ignore_heap' means it will not consider heap memory allocations to be a
101// conflict. Set this based on whether we are calling CheckAndProtect before
102// or after the allocator has initialized the heap.
103bool CheckAndProtect(bool protect, bool ignore_heap, bool print_warnings) {
104 // Ensure that the binary is indeed compiled with -pie.
105 MemoryMappingLayout proc_maps(true);
106 MemoryMappedSegment segment;
107 while (proc_maps.Next(&segment)) {
108 if (segment.start >= HeapMemBeg() && segment.end <= HeapEnd()) {
109 if (ignore_heap) {
110 continue;
111 } else {
112 return false;
113 }
114 }
115
116 // Note: IsAppMem includes if it is heap memory, hence we must
117 // put this check after the heap bounds check.
118 if (IsAppMem(segment.start) && IsAppMem(segment.end - 1))
119 continue;
120
121 // Guard page after the heap end
122 if (segment.start >= HeapMemEnd() && segment.start < HeapEnd()) continue;
123
124 if (segment.protection == 0) // Zero page or mprotected.
125 continue;
126
127 if (segment.start >= VdsoBeg()) // vdso
128 break;
129
130 // Debug output can break tests. Suppress this message in most cases.
131 if (print_warnings)
132 Printf(
133 "WARNING: ThreadSanitizer: unexpected memory mapping 0x%zx-0x%zx\n",
134 segment.start, segment.end);
135
136 return false;
137 }
138
139 if (!protect)
140 return true;
141
142# if SANITIZER_IOS && !SANITIZER_IOSSIM
143 ProtectRange(HeapMemEnd(), ShadowBeg());
144 ProtectRange(ShadowEnd(), MetaShadowBeg());
145 ProtectRange(MetaShadowEnd(), HiAppMemBeg());
146# else
147 ProtectRange(LoAppMemEnd(), ShadowBeg());
148 ProtectRange(ShadowEnd(), MetaShadowBeg());
149 if (MidAppMemBeg()) {
150 ProtectRange(MetaShadowEnd(), MidAppMemBeg());
151 ProtectRange(MidAppMemEnd(), HeapMemBeg());
152 } else {
153 ProtectRange(MetaShadowEnd(), HeapMemBeg());
154 }
155 ProtectRange(HeapEnd(), HiAppMemBeg());
156# endif
157
158# if defined(__s390x__)
159 // Protect the rest of the address space.
160 const uptr user_addr_max_l4 = 0x0020000000000000ull;
161 const uptr user_addr_max_l5 = 0xfffffffffffff000ull;
162 // All the maintained s390x kernels support at least 4-level page tables.
163 ProtectRange(HiAppMemEnd(), user_addr_max_l4);
164 // Older s390x kernels may not support 5-level page tables.
165 TryProtectRange(user_addr_max_l4, user_addr_max_l5);
166#endif
167
168 return true;
169}
170# endif
171
172} // namespace __tsan
173
174#endif // SANITIZER_POSIX