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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 
     18 namespace __sanitizer {
     19 
     20 // ThreadSanitizer for Go uses libc malloc/free.
     21 #if defined(SANITIZER_GO) || defined(SANITIZER_USE_MALLOC)
     22 # if SANITIZER_LINUX && !SANITIZER_ANDROID
     23 extern "C" void *__libc_malloc(uptr size);
     24 extern "C" void __libc_free(void *ptr);
     25 #  define LIBC_MALLOC __libc_malloc
     26 #  define LIBC_FREE __libc_free
     27 # else
     28 #  include <stdlib.h>
     29 #  define LIBC_MALLOC malloc
     30 #  define LIBC_FREE free
     31 # endif
     32 
     33 static void *RawInternalAlloc(uptr size, InternalAllocatorCache *cache) {
     34   (void)cache;
     35   return LIBC_MALLOC(size);
     36 }
     37 
     38 static void RawInternalFree(void *ptr, InternalAllocatorCache *cache) {
     39   (void)cache;
     40   LIBC_FREE(ptr);
     41 }
     42 
     43 InternalAllocator *internal_allocator() {
     44   return 0;
     45 }
     46 
     47 #else  // SANITIZER_GO
     48 
     49 static ALIGNED(64) char internal_alloc_placeholder[sizeof(InternalAllocator)];
     50 static atomic_uint8_t internal_allocator_initialized;
     51 static StaticSpinMutex internal_alloc_init_mu;
     52 
     53 static InternalAllocatorCache internal_allocator_cache;
     54 static StaticSpinMutex internal_allocator_cache_mu;
     55 
     56 InternalAllocator *internal_allocator() {
     57   InternalAllocator *internal_allocator_instance =
     58       reinterpret_cast<InternalAllocator *>(&internal_alloc_placeholder);
     59   if (atomic_load(&internal_allocator_initialized, memory_order_acquire) == 0) {
     60     SpinMutexLock l(&internal_alloc_init_mu);
     61     if (atomic_load(&internal_allocator_initialized, memory_order_relaxed) ==
     62         0) {
     63       internal_allocator_instance->Init(/* may_return_null*/ false);
     64       atomic_store(&internal_allocator_initialized, 1, memory_order_release);
     65     }
     66   }
     67   return internal_allocator_instance;
     68 }
     69 
     70 static void *RawInternalAlloc(uptr size, InternalAllocatorCache *cache) {
     71   if (cache == 0) {
     72     SpinMutexLock l(&internal_allocator_cache_mu);
     73     return internal_allocator()->Allocate(&internal_allocator_cache, size, 8,
     74                                           false);
     75   }
     76   return internal_allocator()->Allocate(cache, size, 8, false);
     77 }
     78 
     79 static void RawInternalFree(void *ptr, InternalAllocatorCache *cache) {
     80   if (cache == 0) {
     81     SpinMutexLock l(&internal_allocator_cache_mu);
     82     return internal_allocator()->Deallocate(&internal_allocator_cache, ptr);
     83   }
     84   internal_allocator()->Deallocate(cache, ptr);
     85 }
     86 
     87 #endif  // SANITIZER_GO
     88 
     89 const u64 kBlockMagic = 0x6A6CB03ABCEBC041ull;
     90 
     91 void *InternalAlloc(uptr size, InternalAllocatorCache *cache) {
     92   if (size + sizeof(u64) < size)
     93     return 0;
     94   void *p = RawInternalAlloc(size + sizeof(u64), cache);
     95   if (p == 0)
     96     return 0;
     97   ((u64*)p)[0] = kBlockMagic;
     98   return (char*)p + sizeof(u64);
     99 }
    100 
    101 void InternalFree(void *addr, InternalAllocatorCache *cache) {
    102   if (addr == 0)
    103     return;
    104   addr = (char*)addr - sizeof(u64);
    105   CHECK_EQ(kBlockMagic, ((u64*)addr)[0]);
    106   ((u64*)addr)[0] = 0;
    107   RawInternalFree(addr, cache);
    108 }
    109 
    110 // LowLevelAllocator
    111 static LowLevelAllocateCallback low_level_alloc_callback;
    112 
    113 void *LowLevelAllocator::Allocate(uptr size) {
    114   // Align allocation size.
    115   size = RoundUpTo(size, 8);
    116   if (allocated_end_ - allocated_current_ < (sptr)size) {
    117     uptr size_to_allocate = Max(size, GetPageSizeCached());
    118     allocated_current_ =
    119         (char*)MmapOrDie(size_to_allocate, __func__);
    120     allocated_end_ = allocated_current_ + size_to_allocate;
    121     if (low_level_alloc_callback) {
    122       low_level_alloc_callback((uptr)allocated_current_,
    123                                size_to_allocate);
    124     }
    125   }
    126   CHECK(allocated_end_ - allocated_current_ >= (sptr)size);
    127   void *res = allocated_current_;
    128   allocated_current_ += size;
    129   return res;
    130 }
    131 
    132 void SetLowLevelAllocateCallback(LowLevelAllocateCallback callback) {
    133   low_level_alloc_callback = callback;
    134 }
    135 
    136 bool CallocShouldReturnNullDueToOverflow(uptr size, uptr n) {
    137   if (!size) return false;
    138   uptr max = (uptr)-1L;
    139   return (max / size) < n;
    140 }
    141 
    142 void NORETURN ReportAllocatorCannotReturnNull() {
    143   Report("%s's allocator is terminating the process instead of returning 0\n",
    144          SanitizerToolName);
    145   Report("If you don't like this behavior set allocator_may_return_null=1\n");
    146   CHECK(0);
    147   Die();
    148 }
    149 
    150 }  // namespace __sanitizer
    151