1 //===-- sanitizer_tls_get_addr.h --------------------------------*- C++ -*-===// 2 // 3 // This file is distributed under the University of Illinois Open Source 4 // License. See LICENSE.TXT for details. 5 // 6 //===----------------------------------------------------------------------===// 7 // 8 // Handle the __tls_get_addr call. 9 // 10 // All this magic is specific to glibc and is required to workaround 11 // the lack of interface that would tell us about the Dynamic TLS (DTLS). 12 // https://sourceware.org/bugzilla/show_bug.cgi?id=16291 13 // 14 // The matters get worse because the glibc implementation changed between 15 // 2.18 and 2.19: 16 // https://groups.google.com/forum/#!topic/address-sanitizer/BfwYD8HMxTM 17 // 18 // Before 2.19, every DTLS chunk is allocated with __libc_memalign, 19 // which we intercept and thus know where is the DTLS. 20 // Since 2.19, DTLS chunks are allocated with __signal_safe_memalign, 21 // which is an internal function that wraps a mmap call, neither of which 22 // we can intercept. Luckily, __signal_safe_memalign has a simple parseable 23 // header which we can use. 24 // 25 //===----------------------------------------------------------------------===// 26 27 #ifndef SANITIZER_TLS_GET_ADDR_H 28 #define SANITIZER_TLS_GET_ADDR_H 29 30 #include "sanitizer_common.h" 31 32 namespace __sanitizer { 33 34 struct DTLS { 35 // Array of DTLS chunks for the current Thread. 36 // If beg == 0, the chunk is unused. 37 struct DTV { 38 uptr beg, size; 39 }; 40 41 uptr dtv_size; 42 DTV *dtv; // dtv_size elements, allocated by MmapOrDie. 43 44 // Auxiliary fields, don't access them outside sanitizer_tls_get_addr.cc 45 uptr last_memalign_size; 46 uptr last_memalign_ptr; 47 }; 48 49 // Returns pointer and size of a linker-allocated TLS block. 50 // Each block is returned exactly once. 51 DTLS::DTV *DTLS_on_tls_get_addr(void *arg, void *res, uptr static_tls_begin, 52 uptr static_tls_end); 53 void DTLS_on_libc_memalign(void *ptr, uptr size); 54 DTLS *DTLS_Get(); 55 void DTLS_Destroy(); // Make sure to call this before the thread is destroyed. 56 // Returns true if DTLS of suspended thread is in destruction process. 57 bool DTLSInDestruction(DTLS *dtls); 58 59 } // namespace __sanitizer 60 61 #endif // SANITIZER_TLS_GET_ADDR_H 62