[Sanitizers] Make sanitizer allocator linker-initialize compliant.

[alekseyshl]

Summary

These four SpinMutex ctors was the only code executed in the ctor for
the static __asan::Allocator instance (same for the other sanitizers
allocators), which is supposed to be fully linker-initialized.

Also, when the global ctor for this allocator instance is executed,
this instance might already be initialized by __asan_init called from
.preinit_array.

Issue: https://github.com/google/sanitizers/issues/194

[cryptoad]

Interesting I was looking at that recently!
If you could add the one in scudo_allocator_secondary.h as well in this patch it would be great. Otherwise I can do a separate one.

[cryptoad]

Please ignore the last comment I'll do a separate patch, Scudo doesn't belong in this one.

[filcab]

Clang still warns:

/Users/filcab/dev/llvm/compiler-rt/lib/asan/asan_allocator.cc:793:18: warning: declaration requires a global constructor [-Wglobal-constructors]
static Allocator instance(LINKER_INITIALIZED);
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.

[filcab]

In D48142#1142349, @filcab wrote:

Clang still warns:

/Users/filcab/dev/llvm/compiler-rt/lib/asan/asan_allocator.cc:793:18: warning: declaration requires a global constructor [-Wglobal-constructors]
static Allocator instance(LINKER_INITIALIZED);
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.

Ah, that's the Asan allocator, which might be bringing something else on. It's probably not about this patch. Sorry for the noise.

[alekseyshl]

In D48142#1142351, @filcab wrote:

In D48142#1142349, @filcab wrote:

Clang still warns:

/Users/filcab/dev/llvm/compiler-rt/lib/asan/asan_allocator.cc:793:18: warning: declaration requires a global constructor [-Wglobal-constructors]
static Allocator instance(LINKER_INITIALIZED);
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.

Ah, that's the Asan allocator, which might be bringing something else on. It's probably not about this patch. Sorry for the noise.

Yep, clang warns about all of those LINKER_INITIALIZED instances, although no code ends up in the binary. Well, maybe this warning is worth investigating and improving...

lib/sanitizer_common/sanitizer_allocator_secondary.h

private:
   uptr page_size_;
   Header **chunks_;
   PtrArrayT ptr_array_;
   uptr n_chunks_;
   bool chunks_sorted_;
   struct Stats {
     uptr n_allocs, n_frees, currently_allocated, max_allocated, by_size_log[64];
   } stats;
-  SpinMutex mutex_;
+  StaticSpinMutex mutex_;
 };
 

lib/sanitizer_common/sanitizer_allocator_stats.h

for (;;) {
         break;
     }
     // All stats must be non-negative.
     for (int i = 0; i < AllocatorStatCount; i++)
       s[i] = ((sptr)s[i]) >= 0 ? s[i] : 0;
   }
 
  private:
-  mutable SpinMutex mu_;
+  mutable StaticSpinMutex mu_;
 };
 
 

lib/sanitizer_common/sanitizer_quarantine.h

public:
   void Init(uptr size, uptr cache_size) {
     // Thread local quarantine size can be zero only when global quarantine size
     // is zero (it allows us to perform just one atomic read per Put() call).
     CHECK((size == 0 && cache_size == 0) || cache_size != 0);
 
     atomic_store_relaxed(&max_size_, size);
     atomic_store_relaxed(&min_size_, size / 10 * 9);  // 90% of max size.
     atomic_store_relaxed(&max_cache_size_, cache_size);
+
+    cache_mutex_.Init();
+    recycle_mutex_.Init();
   }
 
   uptr GetSize() const { return atomic_load_relaxed(&max_size_); }
   uptr GetCacheSize() const {
     return atomic_load_relaxed(&max_cache_size_);
   }
 
   void Put(Cache *c, Callback cb, Node *ptr, uptr size) {

 
  private:
   // Read-only data.
   char pad0_[kCacheLineSize];
   atomic_uintptr_t max_size_;
   atomic_uintptr_t min_size_;
   atomic_uintptr_t max_cache_size_;
   char pad1_[kCacheLineSize];
-  SpinMutex cache_mutex_;
-  SpinMutex recycle_mutex_;
+  StaticSpinMutex cache_mutex_;
+  StaticSpinMutex recycle_mutex_;
   Cache cache_;
   char pad2_[kCacheLineSize];
 
   void NOINLINE Recycle(uptr min_size, Callback cb) {
     Cache tmp;
     {
       SpinMutexLock l(&cache_mutex_);
       // Go over the batches and merge partially filled ones to