1 /* 2 * one_time_construction.cpp 3 * 4 * Copyright 2006 The Android Open Source Project 5 * 6 * This file contains C++ ABI support functions for one time 7 * constructors as defined in the "Run-time ABI for the ARM Architecture" 8 * section 4.4.2 9 */ 10 11 #include <stddef.h> 12 #include <sys/atomics.h> 13 #include <bionic_futex.h> 14 #include <bionic_atomic_inline.h> 15 16 extern "C" int __cxa_guard_acquire(int volatile * gv) 17 { 18 // 0 -> 2, return 1 19 // 2 -> 6, wait and return 0 20 // 6 untouched, wait and return 0 21 // 1 untouched, return 0 22 retry: 23 if (__atomic_cmpxchg(0, 0x2, gv) == 0) { 24 ANDROID_MEMBAR_FULL(); 25 return 1; 26 } 27 __atomic_cmpxchg(0x2, 0x6, gv); // Indicate there is a waiter 28 __futex_wait(gv, 0x6, NULL); 29 30 if(*gv != 1) // __cxa_guard_abort was called, let every thread try since there is no return code for this condition 31 goto retry; 32 33 ANDROID_MEMBAR_FULL(); 34 return 0; 35 } 36 37 extern "C" void __cxa_guard_release(int volatile * gv) 38 { 39 // 2 -> 1 40 // 6 -> 1, and wake 41 ANDROID_MEMBAR_FULL(); 42 if (__atomic_cmpxchg(0x2, 0x1, gv) == 0) { 43 return; 44 } 45 46 *gv = 0x1; 47 __futex_wake(gv, 0x7fffffff); 48 } 49 50 extern "C" void __cxa_guard_abort(int volatile * gv) 51 { 52 ANDROID_MEMBAR_FULL(); 53 *gv = 0; 54 __futex_wake(gv, 0x7fffffff); 55 } 56
