1 //===---------- emutls.c - Implements __emutls_get_address ---------------===//
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
18 //  - Android versions older than M lack __cxa_thread_atexit_impl, so apps
20 //  - Apps might use __thread/thread_local variables in pthread destructors.
22 // after the final malloc/free call to free its thread-specific data (see
31 // sized element in this array. Disable this for warn-as-error builds.
38   uintptr_t size; // number of elements in the 'data' array  member
65 static __inline void *emutls_memalign_alloc(size_t align, size_t size) {  in emutls_memalign_alloc()  argument
68   if (posix_memalign(&base, align, size) != 0)  in emutls_memalign_alloc()
71 #define EXTRA_ALIGN_PTR_BYTES (align - 1 + sizeof(void *))  in emutls_memalign_alloc()
73   if ((object = (char *)malloc(EXTRA_ALIGN_PTR_BYTES + size)) == NULL)  in emutls_memalign_alloc()
76                   ~(uintptr_t)(align - 1));  in emutls_memalign_alloc()
78   ((void **)base)[-1] = object;  in emutls_memalign_alloc()
87   // The mallocated address is in ((void**)base)[-1]  in emutls_memalign_free()
88   free(((void **)base)[-1]);  in emutls_memalign_free()
102   if (array->skip_destructor_rounds > 0) {  in emutls_key_destructor()
106     // Delay the emutls deallocation to accommodate other end-of-thread  in emutls_key_destructor()
109     array->skip_destructor_rounds--;  in emutls_key_destructor()
163 static __inline void *emutls_memalign_alloc(size_t align, size_t size) {  in emutls_memalign_alloc()  argument
164   void *base = _aligned_malloc(size, align);  in emutls_memalign_alloc()
239   // These return the previous value - but since we do an OR with 0,  in __atomic_load_n()
263     for (i = 0; i < array->size; ++i) {  in emutls_shutdown()
264       if (array->data[i])  in emutls_shutdown()
265         emutls_memalign_free(array->data[i]);  in emutls_shutdown()
272 // If xyz has non-zero initial value, __emutls_v.xyz's "value"
277   // zeros.  We can use variables of size_t to operate on size and
278   // align.
279   gcc_word size;  // size of the object in bytes  member
280   gcc_word align; // alignment of the object in bytes  member
282     uintptr_t index; // data[index-1] is the object address
285   void *value; // null or non-zero initial value for the object
288 // Emulated TLS objects are always allocated at run-time.
294   size_t size = control->size;  in emutls_allocate_object()  local
295   size_t align = control->align;  in emutls_allocate_object()  local
297   if (align < sizeof(void *))  in emutls_allocate_object()
298     align = sizeof(void *);  in emutls_allocate_object()
299   // Make sure that align is power of 2.  in emutls_allocate_object()
300   if ((align & (align - 1)) != 0)  in emutls_allocate_object()
303   base = emutls_memalign_alloc(align, size);  in emutls_allocate_object()
304   if (control->value)  in emutls_allocate_object()
305     memcpy(base, control->value, size);  in emutls_allocate_object()
307     memset(base, 0, size);  in emutls_allocate_object()
311 // Returns control->object.index; set index if not allocated yet.
313   uintptr_t index = __atomic_load_n(&control->object.index, __ATOMIC_ACQUIRE);  in emutls_get_index()
317     index = control->object.index;  in emutls_get_index()
320       __atomic_store_n(&control->object.index, index, __ATOMIC_RELEASE);  in emutls_get_index()
329                                                  uintptr_t size) {  in emutls_check_array_set_size()  argument
332   array->size = size;  in emutls_check_array_set_size()
336 // Returns the new 'data' array size, number of elements,
341   // Round up the emutls_address_array size to multiple of 16.  in emutls_new_data_array_size()
343   return ((index + header_words + 15) & ~((uintptr_t)15)) - header_words;  in emutls_new_data_array_size()
346 // Returns the size in bytes required for an emutls_address_array with
353 // Extends its size if necessary to hold address at index.
361       memset(array->data, 0, new_size * sizeof(void *));  in emutls_get_address_array()
362       array->skip_destructor_rounds = EMUTLS_SKIP_DESTRUCTOR_ROUNDS;  in emutls_get_address_array()
365   } else if (index > array->size) {  in emutls_get_address_array()
366     uintptr_t orig_size = array->size;  in emutls_get_address_array()
370       memset(array->data + orig_size, 0,  in emutls_get_address_array()
371              (new_size - orig_size) * sizeof(void *));  in emutls_get_address_array()
386 // with -Bsymbolic or -Bsymbolic-functions, and it also won't work on Windows,
394   emutls_address_array *array = emutls_get_address_array(index--);  in __emutls_get_address()
395   if (array->data[index] == NULL)  in __emutls_get_address()
396     array->data[index] = emutls_allocate_object(control);  in __emutls_get_address()
397   return array->data[index];  in __emutls_get_address()