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1 //===-- sanitizer_allocator.cc --------------------------------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file is shared between AddressSanitizer and ThreadSanitizer
11 // run-time libraries.
12 // This allocator is used inside run-times.
13 //===----------------------------------------------------------------------===//
14 
15 #include "sanitizer_allocator.h"
16 #include "sanitizer_allocator_internal.h"
17 #include "sanitizer_common.h"
18 
19 namespace __sanitizer {
20 
21 // ThreadSanitizer for Go uses libc malloc/free.
22 #if defined(SANITIZER_GO) || defined(SANITIZER_USE_MALLOC)
23 # if SANITIZER_LINUX && !SANITIZER_ANDROID
24 extern "C" void *__libc_malloc(uptr size);
25 extern "C" void *__libc_memalign(uptr alignment, uptr size);
26 extern "C" void *__libc_realloc(void *ptr, uptr size);
27 extern "C" void __libc_free(void *ptr);
28 # else
29 #  include <stdlib.h>
30 #  define __libc_malloc malloc
31 static void *__libc_memalign(uptr alignment, uptr size) {
32   void *p;
33   uptr error = posix_memalign(&p, alignment, size);
34   if (error) return nullptr;
35   return p;
36 }
37 #  define __libc_realloc realloc
38 #  define __libc_free free
39 # endif
40 
RawInternalAlloc(uptr size,InternalAllocatorCache * cache,uptr alignment)41 static void *RawInternalAlloc(uptr size, InternalAllocatorCache *cache,
42                               uptr alignment) {
43   (void)cache;
44   if (alignment == 0)
45     return __libc_malloc(size);
46   else
47     return __libc_memalign(alignment, size);
48 }
49 
RawInternalRealloc(void * ptr,uptr size,InternalAllocatorCache * cache)50 static void *RawInternalRealloc(void *ptr, uptr size,
51                                 InternalAllocatorCache *cache) {
52   (void)cache;
53   return __libc_realloc(ptr, size);
54 }
55 
RawInternalFree(void * ptr,InternalAllocatorCache * cache)56 static void RawInternalFree(void *ptr, InternalAllocatorCache *cache) {
57   (void)cache;
58   __libc_free(ptr);
59 }
60 
internal_allocator()61 InternalAllocator *internal_allocator() {
62   return 0;
63 }
64 
65 #else  // defined(SANITIZER_GO) || defined(SANITIZER_USE_MALLOC)
66 
67 static ALIGNED(64) char internal_alloc_placeholder[sizeof(InternalAllocator)];
68 static atomic_uint8_t internal_allocator_initialized;
69 static StaticSpinMutex internal_alloc_init_mu;
70 
71 static InternalAllocatorCache internal_allocator_cache;
72 static StaticSpinMutex internal_allocator_cache_mu;
73 
74 InternalAllocator *internal_allocator() {
75   InternalAllocator *internal_allocator_instance =
76       reinterpret_cast<InternalAllocator *>(&internal_alloc_placeholder);
77   if (atomic_load(&internal_allocator_initialized, memory_order_acquire) == 0) {
78     SpinMutexLock l(&internal_alloc_init_mu);
79     if (atomic_load(&internal_allocator_initialized, memory_order_relaxed) ==
80         0) {
81       internal_allocator_instance->Init(/* may_return_null*/ false);
82       atomic_store(&internal_allocator_initialized, 1, memory_order_release);
83     }
84   }
85   return internal_allocator_instance;
86 }
87 
88 static void *RawInternalAlloc(uptr size, InternalAllocatorCache *cache,
89                               uptr alignment) {
90   if (alignment == 0) alignment = 8;
91   if (cache == 0) {
92     SpinMutexLock l(&internal_allocator_cache_mu);
93     return internal_allocator()->Allocate(&internal_allocator_cache, size,
94                                           alignment, false);
95   }
96   return internal_allocator()->Allocate(cache, size, alignment, false);
97 }
98 
99 static void *RawInternalRealloc(void *ptr, uptr size,
100                                 InternalAllocatorCache *cache) {
101   uptr alignment = 8;
102   if (cache == 0) {
103     SpinMutexLock l(&internal_allocator_cache_mu);
104     return internal_allocator()->Reallocate(&internal_allocator_cache, ptr,
105                                             size, alignment);
106   }
107   return internal_allocator()->Reallocate(cache, ptr, size, alignment);
108 }
109 
110 static void RawInternalFree(void *ptr, InternalAllocatorCache *cache) {
111   if (!cache) {
112     SpinMutexLock l(&internal_allocator_cache_mu);
113     return internal_allocator()->Deallocate(&internal_allocator_cache, ptr);
114   }
115   internal_allocator()->Deallocate(cache, ptr);
116 }
117 
118 #endif  // defined(SANITIZER_GO) || defined(SANITIZER_USE_MALLOC)
119 
120 const u64 kBlockMagic = 0x6A6CB03ABCEBC041ull;
121 
InternalAlloc(uptr size,InternalAllocatorCache * cache,uptr alignment)122 void *InternalAlloc(uptr size, InternalAllocatorCache *cache, uptr alignment) {
123   if (size + sizeof(u64) < size)
124     return nullptr;
125   void *p = RawInternalAlloc(size + sizeof(u64), cache, alignment);
126   if (!p)
127     return nullptr;
128   ((u64*)p)[0] = kBlockMagic;
129   return (char*)p + sizeof(u64);
130 }
131 
InternalRealloc(void * addr,uptr size,InternalAllocatorCache * cache)132 void *InternalRealloc(void *addr, uptr size, InternalAllocatorCache *cache) {
133   if (!addr)
134     return InternalAlloc(size, cache);
135   if (size + sizeof(u64) < size)
136     return nullptr;
137   addr = (char*)addr - sizeof(u64);
138   size = size + sizeof(u64);
139   CHECK_EQ(kBlockMagic, ((u64*)addr)[0]);
140   void *p = RawInternalRealloc(addr, size, cache);
141   if (!p)
142     return nullptr;
143   return (char*)p + sizeof(u64);
144 }
145 
InternalCalloc(uptr count,uptr size,InternalAllocatorCache * cache)146 void *InternalCalloc(uptr count, uptr size, InternalAllocatorCache *cache) {
147   if (CallocShouldReturnNullDueToOverflow(count, size))
148     return internal_allocator()->ReturnNullOrDie();
149   void *p = InternalAlloc(count * size, cache);
150   if (p) internal_memset(p, 0, count * size);
151   return p;
152 }
153 
InternalFree(void * addr,InternalAllocatorCache * cache)154 void InternalFree(void *addr, InternalAllocatorCache *cache) {
155   if (!addr)
156     return;
157   addr = (char*)addr - sizeof(u64);
158   CHECK_EQ(kBlockMagic, ((u64*)addr)[0]);
159   ((u64*)addr)[0] = 0;
160   RawInternalFree(addr, cache);
161 }
162 
163 // LowLevelAllocator
164 static LowLevelAllocateCallback low_level_alloc_callback;
165 
Allocate(uptr size)166 void *LowLevelAllocator::Allocate(uptr size) {
167   // Align allocation size.
168   size = RoundUpTo(size, 8);
169   if (allocated_end_ - allocated_current_ < (sptr)size) {
170     uptr size_to_allocate = Max(size, GetPageSizeCached());
171     allocated_current_ =
172         (char*)MmapOrDie(size_to_allocate, __func__);
173     allocated_end_ = allocated_current_ + size_to_allocate;
174     if (low_level_alloc_callback) {
175       low_level_alloc_callback((uptr)allocated_current_,
176                                size_to_allocate);
177     }
178   }
179   CHECK(allocated_end_ - allocated_current_ >= (sptr)size);
180   void *res = allocated_current_;
181   allocated_current_ += size;
182   return res;
183 }
184 
SetLowLevelAllocateCallback(LowLevelAllocateCallback callback)185 void SetLowLevelAllocateCallback(LowLevelAllocateCallback callback) {
186   low_level_alloc_callback = callback;
187 }
188 
CallocShouldReturnNullDueToOverflow(uptr size,uptr n)189 bool CallocShouldReturnNullDueToOverflow(uptr size, uptr n) {
190   if (!size) return false;
191   uptr max = (uptr)-1L;
192   return (max / size) < n;
193 }
194 
ReportAllocatorCannotReturnNull()195 void NORETURN ReportAllocatorCannotReturnNull() {
196   Report("%s's allocator is terminating the process instead of returning 0\n",
197          SanitizerToolName);
198   Report("If you don't like this behavior set allocator_may_return_null=1\n");
199   CHECK(0);
200   Die();
201 }
202 
203 } // namespace __sanitizer
204