1 //===-- random.cpp ----------------------------------------------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #include "gwp_asan/random.h" 10 #include "gwp_asan/common.h" 11 12 #include <time.h> 13 14 // Initialised to a magic constant so that an uninitialised GWP-ASan won't 15 // regenerate its sample counter for as long as possible. The xorshift32() 16 // algorithm used below results in getRandomUnsigned32(0xff82eb50) == 17 // 0xfffffea4. 18 GWP_ASAN_TLS_INITIAL_EXEC uint32_t RandomState = 0xff82eb50; 19 20 namespace gwp_asan { initPRNG()21void initPRNG() { 22 RandomState = time(nullptr) + getThreadID(); 23 } 24 getRandomUnsigned32()25uint32_t getRandomUnsigned32() { 26 RandomState ^= RandomState << 13; 27 RandomState ^= RandomState >> 17; 28 RandomState ^= RandomState << 5; 29 return RandomState; 30 } 31 } // namespace gwp_asan 32