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