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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 #include "sanitizer_allocator.h"
     15 #include "sanitizer_allocator_internal.h"
     16 #include "sanitizer_common.h"
     17 #include "sanitizer_flags.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_free(void *ptr);
     26 #  define LIBC_MALLOC __libc_malloc
     27 #  define LIBC_FREE __libc_free
     28 # else
     29 #  include <stdlib.h>
     30 #  define LIBC_MALLOC malloc
     31 #  define LIBC_FREE free
     32 # endif
     33 
     34 static void *RawInternalAlloc(uptr size, InternalAllocatorCache *cache) {
     35   (void)cache;
     36   return LIBC_MALLOC(size);
     37 }
     38 
     39 static void RawInternalFree(void *ptr, InternalAllocatorCache *cache) {
     40   (void)cache;
     41   LIBC_FREE(ptr);
     42 }
     43 
     44 InternalAllocator *internal_allocator() {
     45   return 0;
     46 }
     47 
     48 #else  // SANITIZER_GO
     49 
     50 static ALIGNED(64) char internal_alloc_placeholder[sizeof(InternalAllocator)];
     51 static atomic_uint8_t internal_allocator_initialized;
     52 static StaticSpinMutex internal_alloc_init_mu;
     53 
     54 static InternalAllocatorCache internal_allocator_cache;
     55 static StaticSpinMutex internal_allocator_cache_mu;
     56 
     57 InternalAllocator *internal_allocator() {
     58   InternalAllocator *internal_allocator_instance =
     59       reinterpret_cast<InternalAllocator *>(&internal_alloc_placeholder);
     60   if (atomic_load(&internal_allocator_initialized, memory_order_acquire) == 0) {
     61     SpinMutexLock l(&internal_alloc_init_mu);
     62     if (atomic_load(&internal_allocator_initialized, memory_order_relaxed) ==
     63         0) {
     64       internal_allocator_instance->Init();
     65       atomic_store(&internal_allocator_initialized, 1, memory_order_release);
     66     }
     67   }
     68   return internal_allocator_instance;
     69 }
     70 
     71 static void *RawInternalAlloc(uptr size, InternalAllocatorCache *cache) {
     72   if (cache == 0) {
     73     SpinMutexLock l(&internal_allocator_cache_mu);
     74     return internal_allocator()->Allocate(&internal_allocator_cache, size, 8,
     75                                           false);
     76   }
     77   return internal_allocator()->Allocate(cache, size, 8, false);
     78 }
     79 
     80 static void RawInternalFree(void *ptr, InternalAllocatorCache *cache) {
     81   if (cache == 0) {
     82     SpinMutexLock l(&internal_allocator_cache_mu);
     83     return internal_allocator()->Deallocate(&internal_allocator_cache, ptr);
     84   }
     85   internal_allocator()->Deallocate(cache, ptr);
     86 }
     87 
     88 #endif  // SANITIZER_GO
     89 
     90 const u64 kBlockMagic = 0x6A6CB03ABCEBC041ull;
     91 
     92 void *InternalAlloc(uptr size, InternalAllocatorCache *cache) {
     93   if (size + sizeof(u64) < size)
     94     return 0;
     95   void *p = RawInternalAlloc(size + sizeof(u64), cache);
     96   if (p == 0)
     97     return 0;
     98   ((u64*)p)[0] = kBlockMagic;
     99   return (char*)p + sizeof(u64);
    100 }
    101 
    102 void InternalFree(void *addr, InternalAllocatorCache *cache) {
    103   if (addr == 0)
    104     return;
    105   addr = (char*)addr - sizeof(u64);
    106   CHECK_EQ(kBlockMagic, ((u64*)addr)[0]);
    107   ((u64*)addr)[0] = 0;
    108   RawInternalFree(addr, cache);
    109 }
    110 
    111 // LowLevelAllocator
    112 static LowLevelAllocateCallback low_level_alloc_callback;
    113 
    114 void *LowLevelAllocator::Allocate(uptr size) {
    115   // Align allocation size.
    116   size = RoundUpTo(size, 8);
    117   if (allocated_end_ - allocated_current_ < (sptr)size) {
    118     uptr size_to_allocate = Max(size, GetPageSizeCached());
    119     allocated_current_ =
    120         (char*)MmapOrDie(size_to_allocate, __func__);
    121     allocated_end_ = allocated_current_ + size_to_allocate;
    122     if (low_level_alloc_callback) {
    123       low_level_alloc_callback((uptr)allocated_current_,
    124                                size_to_allocate);
    125     }
    126   }
    127   CHECK(allocated_end_ - allocated_current_ >= (sptr)size);
    128   void *res = allocated_current_;
    129   allocated_current_ += size;
    130   return res;
    131 }
    132 
    133 void SetLowLevelAllocateCallback(LowLevelAllocateCallback callback) {
    134   low_level_alloc_callback = callback;
    135 }
    136 
    137 bool CallocShouldReturnNullDueToOverflow(uptr size, uptr n) {
    138   if (!size) return false;
    139   uptr max = (uptr)-1L;
    140   return (max / size) < n;
    141 }
    142 
    143 void *AllocatorReturnNull() {
    144   if (common_flags()->allocator_may_return_null)
    145     return 0;
    146   Report("%s's allocator is terminating the process instead of returning 0\n",
    147          SanitizerToolName);
    148   Report("If you don't like this behavior set allocator_may_return_null=1\n");
    149   CHECK(0);
    150   return 0;
    151 }
    152 
    153 }  // namespace __sanitizer
    154