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/* ===---------- emutls.c - Implements __emutls_get_address ---------------=== |
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* |
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* The LLVM Compiler Infrastructure |
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* |
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* This file is dual licensed under the MIT and the University of Illinois Open |
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* Source Licenses. See LICENSE.TXT for details. |
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* |
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* ===----------------------------------------------------------------------=== |
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*/ |
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#include <pthread.h> |
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#include <stdint.h> |
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#include <stdlib.h> |
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#include <string.h> |
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//#include "int_util.h" |
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/* Default is not to use posix_memalign, so systems like Android |
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* can use thread local data without heavier POSIX memory allocators. |
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*/ |
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#ifndef EMUTLS_USE_POSIX_MEMALIGN |
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#define EMUTLS_USE_POSIX_MEMALIGN 0 |
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#endif |
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/* For every TLS variable xyz, |
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* there is one __emutls_control variable named __emutls_v.xyz. |
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* If xyz has non-zero initial value, __emutls_v.xyz's "value" |
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* will point to __emutls_t.xyz, which has the initial value. |
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*/ |
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typedef struct __emutls_control { |
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size_t size; /* size of the object in bytes */ |
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size_t align; /* alignment of the object in bytes */ |
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union { |
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uintptr_t index; /* data[index-1] is the object address */ |
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void* address; /* object address, when in single thread env */ |
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} object; |
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void* value; /* null or non-zero initial value for the object */ |
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} __emutls_control; |
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static inline void* emutls_memalign_alloc(size_t align, size_t size) { |
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void *base; |
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#if EMUTLS_USE_POSIX_MEMALIGN |
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if (posix_memalign(&base, align, size) != 0) |
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abort(); |
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#else |
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#define EXTRA_ALIGN_PTR_BYTES (align - 1 + sizeof(void*)) |
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char* object; |
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if ((object = malloc(EXTRA_ALIGN_PTR_BYTES + size)) == NULL) |
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abort(); |
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base = (void*)(((uintptr_t)(object + EXTRA_ALIGN_PTR_BYTES)) |
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& ~(uintptr_t)(align - 1)); |
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((void**)base)[-1] = object; |
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#endif |
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return base; |
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} |
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static inline void emutls_memalign_free(void* base) { |
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#if EMUTLS_USE_POSIX_MEMALIGN |
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free(base); |
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#else |
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/* The mallocated address is in ((void**)base)[-1] */ |
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free(((void**)base)[-1]); |
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#endif |
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} |
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/* Emulated TLS objects are always allocated at run-time. */ |
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static inline void* emutls_allocate_object(__emutls_control* control) { |
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/* Use standard C types, check with gcc's emutls.o. */ |
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//typedef unsigned int gcc_word __attribute__((mode(word))); |
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//typedef unsigned int gcc_pointer __attribute__((mode(pointer))); |
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//COMPILE_TIME_ASSERT(sizeof(size_t) == sizeof(gcc_word)); |
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//COMPILE_TIME_ASSERT(sizeof(uintptr_t) == sizeof(gcc_pointer)); |
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//COMPILE_TIME_ASSERT(sizeof(uintptr_t) == sizeof(void*)); |
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size_t size = control->size; |
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size_t align = control->align; |
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if (align < sizeof(void*)) |
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align = sizeof(void*); |
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/* Make sure that align is power of 2. */ |
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if ((align & (align - 1)) != 0) |
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abort(); |
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void* base = emutls_memalign_alloc(align, size); |
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if (control->value) |
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memcpy(base, control->value, size); |
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else |
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memset(base, 0, size); |
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return base; |
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} |
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static pthread_mutex_t emutls_mutex = PTHREAD_MUTEX_INITIALIZER; |
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static size_t emutls_num_object = 0; /* number of allocated TLS objects */ |
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typedef struct emutls_address_array { |
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uintptr_t size; /* number of elements in the 'data' array */ |
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void* data[]; |
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} emutls_address_array; |
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static pthread_key_t emutls_pthread_key; |
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static void emutls_key_destructor(void* ptr) { |
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emutls_address_array* array = (emutls_address_array*)ptr; |
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uintptr_t i; |
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for (i = 0; i < array->size; ++i) { |
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if (array->data[i]) |
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emutls_memalign_free(array->data[i]); |
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} |
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free(ptr); |
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} |
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static void emutls_init(void) { |
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if (pthread_key_create(&emutls_pthread_key, emutls_key_destructor) != 0) |
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abort(); |
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} |
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|
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/* Returns control->object.index; set index if not allocated yet. */ |
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static inline uintptr_t emutls_get_index(__emutls_control* control) { |
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uintptr_t index = __atomic_load_n(&control->object.index, __ATOMIC_ACQUIRE); |
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if (!index) { |
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static pthread_once_t once = PTHREAD_ONCE_INIT; |
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pthread_once(&once, emutls_init); |
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pthread_mutex_lock(&emutls_mutex); |
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index = control->object.index; |
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if (!index) { |
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index = ++emutls_num_object; |
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__atomic_store_n(&control->object.index, index, __ATOMIC_RELEASE); |
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} |
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pthread_mutex_unlock(&emutls_mutex); |
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} |
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return index; |
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} |
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|
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/* Updates newly allocated thread local emutls_address_array. */ |
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static inline void emutls_check_array_set_size(emutls_address_array* array, |
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uintptr_t size) { |
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if (array == NULL) |
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abort(); |
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array->size = size; |
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pthread_setspecific(emutls_pthread_key, (void*)array); |
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} |
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/* Returns the new 'data' array size, number of elements, |
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* which must be no smaller than the given index. |
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*/ |
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static inline uintptr_t emutls_new_data_array_size(uintptr_t index) { |
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/* Need to allocate emutls_address_array with one extra slot |
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* to store the data array size. |
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* Round up the emutls_address_array size to multiple of 16. |
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*/ |
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return ((index + 1 + 15) & ~((uintptr_t)15)) - 1; |
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} |
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|
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/* Returns the thread local emutls_address_array. |
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* Extends its size if necessary to hold address at index. |
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*/ |
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static inline emutls_address_array* emutls_get_address_array(uintptr_t index) { |
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emutls_address_array* array = pthread_getspecific(emutls_pthread_key); |
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if (array == NULL) { |
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uintptr_t new_size = emutls_new_data_array_size(index); |
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array = calloc(new_size + 1, sizeof(void*)); |
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emutls_check_array_set_size(array, new_size); |
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} else if (index > array->size) { |
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uintptr_t orig_size = array->size; |
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uintptr_t new_size = emutls_new_data_array_size(index); |
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array = realloc(array, (new_size + 1) * sizeof(void*)); |
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if (array) |
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memset(array->data + orig_size, 0, |
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(new_size - orig_size) * sizeof(void*)); |
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emutls_check_array_set_size(array, new_size); |
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} |
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return array; |
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} |
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|
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void* __emutls_get_address(__emutls_control* control) { |
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uintptr_t index = emutls_get_index(control); |
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emutls_address_array* array = emutls_get_address_array(index); |
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if (array->data[index - 1] == NULL) |
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array->data[index - 1] = emutls_allocate_object(control); |
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return array->data[index - 1]; |
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} |
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