src/libcompiler_builtins/compiler-rt/lib/sanitizer_common/sanitizer_tls_get_addr.h

   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