/* * one_time_construction.cpp * * Copyright 2006 The Android Open Source Project * * This file contains C++ ABI support functions for one time * constructors as defined in the "Run-time ABI for the ARM Architecture" * section 4.4.2 */ #include <stddef.h> #include <sys/atomics.h> #include <bionic_futex.h> #include <bionic_atomic_inline.h> extern "C" int __cxa_guard_acquire(int volatile * gv) { // 0 -> 2, return 1 // 2 -> 6, wait and return 0 // 6 untouched, wait and return 0 // 1 untouched, return 0 retry: if (__atomic_cmpxchg(0, 0x2, gv) == 0) { ANDROID_MEMBAR_FULL(); return 1; } __atomic_cmpxchg(0x2, 0x6, gv); // Indicate there is a waiter __futex_wait(gv, 0x6, NULL); if(*gv != 1) // __cxa_guard_abort was called, let every thread try since there is no return code for this condition goto retry; ANDROID_MEMBAR_FULL(); return 0; } extern "C" void __cxa_guard_release(int volatile * gv) { // 2 -> 1 // 6 -> 1, and wake ANDROID_MEMBAR_FULL(); if (__atomic_cmpxchg(0x2, 0x1, gv) == 0) { return; } *gv = 0x1; __futex_wake(gv, 0x7fffffff); } extern "C" void __cxa_guard_abort(int volatile * gv) { ANDROID_MEMBAR_FULL(); *gv = 0; __futex_wake(gv, 0x7fffffff); }