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53 lines
1.5 KiB
C++
53 lines
1.5 KiB
C++
//===- FuzzerTracePC.cpp - PC tracing--------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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// Trace PCs.
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// This module implements __sanitizer_cov_trace_pc, a callback required
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// for -fsanitize-coverage=trace-pc instrumentation.
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//
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//===----------------------------------------------------------------------===//
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#include "FuzzerInternal.h"
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namespace fuzzer {
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static size_t PreviouslyComputedPCHash;
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static ValueBitMap CurrentPCMap;
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// Merges CurrentPCMap into M, returns the number of new bits.
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size_t PCMapMergeFromCurrent(ValueBitMap &M) {
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if (!PreviouslyComputedPCHash)
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return 0;
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PreviouslyComputedPCHash = 0;
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return M.MergeFrom(CurrentPCMap);
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}
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static void HandlePC(uint32_t PC) {
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// We take 12 bits of PC and mix it with the previous PCs.
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uintptr_t Next = (PreviouslyComputedPCHash << 5) ^ (PC & 4095);
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CurrentPCMap.AddValue(Next);
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PreviouslyComputedPCHash = Next;
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}
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} // namespace fuzzer
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extern "C" {
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__attribute__((visibility("default")))
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void __sanitizer_cov_trace_pc() {
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fuzzer::HandlePC(static_cast<uint32_t>(
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reinterpret_cast<uintptr_t>(__builtin_return_address(0))));
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}
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__attribute__((visibility("default")))
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void __sanitizer_cov_trace_pc_indir(int *) {
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// Stub to allow linking with code built with
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// -fsanitize=indirect-calls,trace-pc.
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// This isn't used currently.
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}
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}
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