1//===-- sanitizer_tls_get_addr.h --------------------------------*- 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// Handle the __tls_get_addr call. 10// 11// All this magic is specific to glibc and is required to workaround 12// the lack of interface that would tell us about the Dynamic TLS (DTLS). 13// https://sourceware.org/bugzilla/show_bug.cgi?id=16291 14// 15// The matters get worse because the glibc implementation changed between 16// 2.18 and 2.19: 17// https://groups.google.com/forum/#!topic/address-sanitizer/BfwYD8HMxTM 18// 19// Before 2.19, every DTLS chunk is allocated with __libc_memalign, 20// which we intercept and thus know where is the DTLS. 21// Since 2.19, DTLS chunks are allocated with __signal_safe_memalign, 22// which is an internal function that wraps a mmap call, neither of which 23// we can intercept. Luckily, __signal_safe_memalign has a simple parseable 24// header which we can use. 25// 26//===----------------------------------------------------------------------===// 27 28#ifndef SANITIZER_TLS_GET_ADDR_H 29#define SANITIZER_TLS_GET_ADDR_H 30 31#include "sanitizer_common.h" 32 33namespace __sanitizer { 34 35struct DTLS { 36 // Array of DTLS chunks for the current Thread. 37 // If beg == 0, the chunk is unused. 38 struct DTV { 39 uptr beg, size; 40 }; 41 42 uptr dtv_size; 43 DTV *dtv; // dtv_size elements, allocated by MmapOrDie. 44 45 // Auxiliary fields, don't access them outside sanitizer_tls_get_addr.cpp 46 uptr last_memalign_size; 47 uptr last_memalign_ptr; 48}; 49 50// Returns pointer and size of a linker-allocated TLS block. 51// Each block is returned exactly once. 52DTLS::DTV *DTLS_on_tls_get_addr(void *arg, void *res, uptr static_tls_begin, 53 uptr static_tls_end); 54void DTLS_on_libc_memalign(void *ptr, uptr size); 55DTLS *DTLS_Get(); 56void DTLS_Destroy(); // Make sure to call this before the thread is destroyed. 57// Returns true if DTLS of suspended thread is in destruction process. 58bool DTLSInDestruction(DTLS *dtls); 59 60} // namespace __sanitizer 61 62#endif // SANITIZER_TLS_GET_ADDR_H 63