1 //===-- sanitizer_allocator.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 shared between AddressSanitizer and ThreadSanitizer
10 // run-time libraries.
11 // This allocator is used inside run-times.
12 //===----------------------------------------------------------------------===//
13 
14 #include "sanitizer_allocator.h"
15 
16 #include "sanitizer_allocator_checks.h"
17 #include "sanitizer_allocator_internal.h"
18 #include "sanitizer_atomic.h"
19 #include "sanitizer_common.h"
20 
21 namespace __sanitizer {
22 
23 // Default allocator names.
24 const char *PrimaryAllocatorName = "SizeClassAllocator";
25 const char *SecondaryAllocatorName = "LargeMmapAllocator";
26 
27 // ThreadSanitizer for Go uses libc malloc/free.
28 #if defined(SANITIZER_USE_MALLOC)
29 # if SANITIZER_LINUX && !SANITIZER_ANDROID
30 extern "C" void *__libc_malloc(uptr size);
31 #  if !SANITIZER_GO
32 extern "C" void *__libc_memalign(uptr alignment, uptr size);
33 #  endif
34 extern "C" void *__libc_realloc(void *ptr, uptr size);
35 extern "C" void __libc_free(void *ptr);
36 # else
37 #  include <stdlib.h>
38 #  define __libc_malloc malloc
39 #  if !SANITIZER_GO
40 static void *__libc_memalign(uptr alignment, uptr size) {
41   void *p;
42   uptr error = posix_memalign(&p, alignment, size);
43   if (error) return nullptr;
44   return p;
45 }
46 #  endif
47 #  define __libc_realloc realloc
48 #  define __libc_free free
49 # endif
50 
51 static void *RawInternalAlloc(uptr size, InternalAllocatorCache *cache,
52                               uptr alignment) {
53   (void)cache;
54 #if !SANITIZER_GO
55   if (alignment == 0)
56     return __libc_malloc(size);
57   else
58     return __libc_memalign(alignment, size);
59 #else
60   // Windows does not provide __libc_memalign/posix_memalign. It provides
61   // __aligned_malloc, but the allocated blocks can't be passed to free,
62   // they need to be passed to __aligned_free. InternalAlloc interface does
63   // not account for such requirement. Alignemnt does not seem to be used
64   // anywhere in runtime, so just call __libc_malloc for now.
65   DCHECK_EQ(alignment, 0);
66   return __libc_malloc(size);
67 #endif
68 }
69 
70 static void *RawInternalRealloc(void *ptr, uptr size,
71                                 InternalAllocatorCache *cache) {
72   (void)cache;
73   return __libc_realloc(ptr, size);
74 }
75 
76 static void RawInternalFree(void *ptr, InternalAllocatorCache *cache) {
77   (void)cache;
78   __libc_free(ptr);
79 }
80 
81 InternalAllocator *internal_allocator() {
82   return 0;
83 }
84 
85 #else  // SANITIZER_GO || defined(SANITIZER_USE_MALLOC)
86 
87 static ALIGNED(64) char internal_alloc_placeholder[sizeof(InternalAllocator)];
88 static atomic_uint8_t internal_allocator_initialized;
89 static StaticSpinMutex internal_alloc_init_mu;
90 
91 static InternalAllocatorCache internal_allocator_cache;
92 static StaticSpinMutex internal_allocator_cache_mu;
93 
94 InternalAllocator *internal_allocator() {
95   InternalAllocator *internal_allocator_instance =
96       reinterpret_cast<InternalAllocator *>(&internal_alloc_placeholder);
97   if (atomic_load(&internal_allocator_initialized, memory_order_acquire) == 0) {
98     SpinMutexLock l(&internal_alloc_init_mu);
99     if (atomic_load(&internal_allocator_initialized, memory_order_relaxed) ==
100         0) {
101       internal_allocator_instance->Init(kReleaseToOSIntervalNever);
102       atomic_store(&internal_allocator_initialized, 1, memory_order_release);
103     }
104   }
105   return internal_allocator_instance;
106 }
107 
108 static void *RawInternalAlloc(uptr size, InternalAllocatorCache *cache,
109                               uptr alignment) {
110   if (alignment == 0) alignment = 8;
111   if (cache == 0) {
112     SpinMutexLock l(&internal_allocator_cache_mu);
113     return internal_allocator()->Allocate(&internal_allocator_cache, size,
114                                           alignment);
115   }
116   return internal_allocator()->Allocate(cache, size, alignment);
117 }
118 
119 static void *RawInternalRealloc(void *ptr, uptr size,
120                                 InternalAllocatorCache *cache) {
121   uptr alignment = 8;
122   if (cache == 0) {
123     SpinMutexLock l(&internal_allocator_cache_mu);
124     return internal_allocator()->Reallocate(&internal_allocator_cache, ptr,
125                                             size, alignment);
126   }
127   return internal_allocator()->Reallocate(cache, ptr, size, alignment);
128 }
129 
130 static void RawInternalFree(void *ptr, InternalAllocatorCache *cache) {
131   if (!cache) {
132     SpinMutexLock l(&internal_allocator_cache_mu);
133     return internal_allocator()->Deallocate(&internal_allocator_cache, ptr);
134   }
135   internal_allocator()->Deallocate(cache, ptr);
136 }
137 
138 #endif  // SANITIZER_GO || defined(SANITIZER_USE_MALLOC)
139 
140 namespace {
141 const u64 kBlockMagic = 0x6A6CB03ABCEBC041ull;
142 
143 struct BlockHeader {
144   u64 magic;
145 };
146 }  // namespace
147 
148 static void NORETURN ReportInternalAllocatorOutOfMemory(uptr requested_size) {
149   SetAllocatorOutOfMemory();
150   Report("FATAL: %s: internal allocator is out of memory trying to allocate "
151          "0x%zx bytes\n", SanitizerToolName, requested_size);
152   Die();
153 }
154 
155 void *InternalAlloc(uptr size, InternalAllocatorCache *cache, uptr alignment) {
156   uptr s = size + sizeof(BlockHeader);
157   if (s < size)
158     return nullptr;
159   BlockHeader *p = (BlockHeader *)RawInternalAlloc(s, cache, alignment);
160   if (UNLIKELY(!p))
161     ReportInternalAllocatorOutOfMemory(s);
162   p->magic = kBlockMagic;
163   return p + 1;
164 }
165 
166 void *InternalRealloc(void *addr, uptr size, InternalAllocatorCache *cache) {
167   if (!addr)
168     return InternalAlloc(size, cache);
169   uptr s = size + sizeof(BlockHeader);
170   if (s < size)
171     return nullptr;
172   BlockHeader *p = (BlockHeader *)addr - 1;
173   CHECK_EQ(kBlockMagic, p->magic);
174   p = (BlockHeader *)RawInternalRealloc(p, s, cache);
175   if (UNLIKELY(!p))
176     ReportInternalAllocatorOutOfMemory(s);
177   return p + 1;
178 }
179 
180 void *InternalReallocArray(void *addr, uptr count, uptr size,
181                            InternalAllocatorCache *cache) {
182   if (UNLIKELY(CheckForCallocOverflow(count, size))) {
183     Report(
184         "FATAL: %s: reallocarray parameters overflow: count * size (%zd * %zd) "
185         "cannot be represented in type size_t\n",
186         SanitizerToolName, count, size);
187     Die();
188   }
189   return InternalRealloc(addr, count * size, cache);
190 }
191 
192 void *InternalCalloc(uptr count, uptr size, InternalAllocatorCache *cache) {
193   if (UNLIKELY(CheckForCallocOverflow(count, size))) {
194     Report("FATAL: %s: calloc parameters overflow: count * size (%zd * %zd) "
195            "cannot be represented in type size_t\n", SanitizerToolName, count,
196            size);
197     Die();
198   }
199   void *p = InternalAlloc(count * size, cache);
200   if (LIKELY(p))
201     internal_memset(p, 0, count * size);
202   return p;
203 }
204 
205 void InternalFree(void *addr, InternalAllocatorCache *cache) {
206   if (!addr)
207     return;
208   BlockHeader *p = (BlockHeader *)addr - 1;
209   CHECK_EQ(kBlockMagic, p->magic);
210   p->magic = 0;
211   RawInternalFree(p, cache);
212 }
213 
214 // LowLevelAllocator
215 constexpr uptr kLowLevelAllocatorDefaultAlignment = 8;
216 static uptr low_level_alloc_min_alignment = kLowLevelAllocatorDefaultAlignment;
217 static LowLevelAllocateCallback low_level_alloc_callback;
218 
219 void *LowLevelAllocator::Allocate(uptr size) {
220   // Align allocation size.
221   size = RoundUpTo(size, low_level_alloc_min_alignment);
222   if (allocated_end_ - allocated_current_ < (sptr)size) {
223     uptr size_to_allocate = RoundUpTo(size, GetPageSizeCached());
224     allocated_current_ =
225         (char*)MmapOrDie(size_to_allocate, __func__);
226     allocated_end_ = allocated_current_ + size_to_allocate;
227     if (low_level_alloc_callback) {
228       low_level_alloc_callback((uptr)allocated_current_,
229                                size_to_allocate);
230     }
231   }
232   CHECK(allocated_end_ - allocated_current_ >= (sptr)size);
233   void *res = allocated_current_;
234   allocated_current_ += size;
235   return res;
236 }
237 
238 void SetLowLevelAllocateMinAlignment(uptr alignment) {
239   CHECK(IsPowerOfTwo(alignment));
240   low_level_alloc_min_alignment = Max(alignment, low_level_alloc_min_alignment);
241 }
242 
243 void SetLowLevelAllocateCallback(LowLevelAllocateCallback callback) {
244   low_level_alloc_callback = callback;
245 }
246 
247 // Allocator's OOM and other errors handling support.
248 
249 static atomic_uint8_t allocator_out_of_memory = {0};
250 static atomic_uint8_t allocator_may_return_null = {0};
251 
252 bool IsAllocatorOutOfMemory() {
253   return atomic_load_relaxed(&allocator_out_of_memory);
254 }
255 
256 void SetAllocatorOutOfMemory() {
257   atomic_store_relaxed(&allocator_out_of_memory, 1);
258 }
259 
260 bool AllocatorMayReturnNull() {
261   return atomic_load(&allocator_may_return_null, memory_order_relaxed);
262 }
263 
264 void SetAllocatorMayReturnNull(bool may_return_null) {
265   atomic_store(&allocator_may_return_null, may_return_null,
266                memory_order_relaxed);
267 }
268 
269 void PrintHintAllocatorCannotReturnNull() {
270   Report("HINT: if you don't care about these errors you may set "
271          "allocator_may_return_null=1\n");
272 }
273 
274 } // namespace __sanitizer
275