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1 //===-- msan_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 a part of MemorySanitizer.
11 //
12 // MemorySanitizer allocator.
13 //===----------------------------------------------------------------------===//
14 
15 #include "sanitizer_common/sanitizer_allocator.h"
16 #include "sanitizer_common/sanitizer_stackdepot.h"
17 #include "msan.h"
18 
19 namespace __msan {
20 
21 struct Metadata {
22   uptr requested_size;
23 };
24 
25 static const uptr kAllocatorSpace = 0x600000000000ULL;
26 static const uptr kAllocatorSize   = 0x80000000000;  // 8T.
27 static const uptr kMetadataSize  = sizeof(Metadata);
28 
29 typedef SizeClassAllocator64<kAllocatorSpace, kAllocatorSize, kMetadataSize,
30                              DefaultSizeClassMap> PrimaryAllocator;
31 typedef SizeClassAllocatorLocalCache<PrimaryAllocator> AllocatorCache;
32 typedef LargeMmapAllocator<> SecondaryAllocator;
33 typedef CombinedAllocator<PrimaryAllocator, AllocatorCache,
34                           SecondaryAllocator> Allocator;
35 
36 static THREADLOCAL AllocatorCache cache;
37 static Allocator allocator;
38 
39 static int inited = 0;
40 
Init()41 static inline void Init() {
42   if (inited) return;
43   __msan_init();
44   inited = true;  // this must happen before any threads are created.
45   allocator.Init();
46 }
47 
MsanAllocate(StackTrace * stack,uptr size,uptr alignment,bool zeroise)48 static void *MsanAllocate(StackTrace *stack, uptr size,
49                           uptr alignment, bool zeroise) {
50   Init();
51   void *res = allocator.Allocate(&cache, size, alignment, false);
52   Metadata *meta = reinterpret_cast<Metadata*>(allocator.GetMetaData(res));
53   meta->requested_size = size;
54   if (zeroise)
55     __msan_clear_and_unpoison(res, size);
56   else if (flags()->poison_in_malloc)
57     __msan_poison(res, size);
58   if (__msan_get_track_origins()) {
59     u32 stack_id = StackDepotPut(stack->trace, stack->size);
60     CHECK(stack_id);
61     CHECK_EQ((stack_id >> 31), 0);  // Higher bit is occupied by stack origins.
62     __msan_set_origin(res, size, stack_id);
63   }
64   return res;
65 }
66 
MsanDeallocate(void * p)67 void MsanDeallocate(void *p) {
68   CHECK(p);
69   Init();
70   Metadata *meta = reinterpret_cast<Metadata*>(allocator.GetMetaData(p));
71   uptr size = meta->requested_size;
72   // This memory will not be reused by anyone else, so we are free to keep it
73   // poisoned.
74   __msan_poison(p, size);
75   if (__msan_get_track_origins())
76     __msan_set_origin(p, size, -1);
77   allocator.Deallocate(&cache, p);
78 }
79 
MsanReallocate(StackTrace * stack,void * old_p,uptr new_size,uptr alignment,bool zeroise)80 void *MsanReallocate(StackTrace *stack, void *old_p, uptr new_size,
81                      uptr alignment, bool zeroise) {
82   if (!old_p)
83     return MsanAllocate(stack, new_size, alignment, zeroise);
84   if (!new_size) {
85     MsanDeallocate(old_p);
86     return 0;
87   }
88   Metadata *meta = reinterpret_cast<Metadata*>(allocator.GetMetaData(old_p));
89   uptr old_size = meta->requested_size;
90   uptr actually_allocated_size = allocator.GetActuallyAllocatedSize(old_p);
91   if (new_size <= actually_allocated_size) {
92     // We are not reallocating here.
93     meta->requested_size = new_size;
94     if (new_size > old_size)
95       __msan_poison((char*)old_p + old_size, new_size - old_size);
96     return old_p;
97   }
98   uptr memcpy_size = Min(new_size, old_size);
99   void *new_p = MsanAllocate(stack, new_size, alignment, zeroise);
100   // Printf("realloc: old_size %zd new_size %zd\n", old_size, new_size);
101   if (new_p)
102     __msan_memcpy(new_p, old_p, memcpy_size);
103   MsanDeallocate(old_p);
104   return new_p;
105 }
106 
107 }  // namespace __msan
108