80 lines
2.7 KiB
C++
80 lines
2.7 KiB
C++
//===-- sanitizer_tls_get_addr.h --------------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// Handle the __tls_get_addr call.
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//
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// All this magic is specific to glibc and is required to workaround
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// the lack of interface that would tell us about the Dynamic TLS (DTLS).
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// https://sourceware.org/bugzilla/show_bug.cgi?id=16291
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//
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// The matters get worse because the glibc implementation changed between
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// 2.18 and 2.19:
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// https://groups.google.com/forum/#!topic/address-sanitizer/BfwYD8HMxTM
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//
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// Before 2.19, every DTLS chunk is allocated with __libc_memalign,
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// which we intercept and thus know where is the DTLS.
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// Since 2.19, DTLS chunks are allocated with __signal_safe_memalign,
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// which is an internal function that wraps a mmap call, neither of which
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// we can intercept. Luckily, __signal_safe_memalign has a simple parseable
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// header which we can use.
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//
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//===----------------------------------------------------------------------===//
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#ifndef SANITIZER_TLS_GET_ADDR_H
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#define SANITIZER_TLS_GET_ADDR_H
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#include "sanitizer_atomic.h"
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#include "sanitizer_common.h"
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namespace __sanitizer {
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struct DTLS {
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// Array of DTLS chunks for the current Thread.
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// If beg == 0, the chunk is unused.
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struct DTV {
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uptr beg, size;
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};
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struct DTVBlock {
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atomic_uintptr_t next;
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DTV dtvs[(4096UL - sizeof(next)) / sizeof(DTLS::DTV)];
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};
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static_assert(sizeof(DTVBlock) <= 4096UL, "Unexpected block size");
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atomic_uintptr_t dtv_block;
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// Auxiliary fields, don't access them outside sanitizer_tls_get_addr.cpp
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uptr last_memalign_size;
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uptr last_memalign_ptr;
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};
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template <typename Fn>
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void ForEachDVT(DTLS *dtls, const Fn &fn) {
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DTLS::DTVBlock *block =
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(DTLS::DTVBlock *)atomic_load(&dtls->dtv_block, memory_order_acquire);
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while (block) {
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int id = 0;
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for (auto &d : block->dtvs) fn(d, id++);
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block = (DTLS::DTVBlock *)atomic_load(&block->next, memory_order_acquire);
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}
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}
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// Returns pointer and size of a linker-allocated TLS block.
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// Each block is returned exactly once.
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DTLS::DTV *DTLS_on_tls_get_addr(void *arg, void *res, uptr static_tls_begin,
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uptr static_tls_end);
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void DTLS_on_libc_memalign(void *ptr, uptr size);
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DTLS *DTLS_Get();
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void DTLS_Destroy(); // Make sure to call this before the thread is destroyed.
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// Returns true if DTLS of suspended thread is in destruction process.
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bool DTLSInDestruction(DTLS *dtls);
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} // namespace __sanitizer
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#endif // SANITIZER_TLS_GET_ADDR_H
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