forked from OSchip/llvm-project
81 lines
3.1 KiB
C++
81 lines
3.1 KiB
C++
//===- FuzzerExtraCountersWindows.cpp - Extra coverage counters for Win32 -===//
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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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// Extra coverage counters defined by user code for Windows.
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//===----------------------------------------------------------------------===//
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#include "FuzzerPlatform.h"
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#include <cstdint>
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#if LIBFUZZER_WINDOWS
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#include <windows.h>
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namespace fuzzer {
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//
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// The __start___libfuzzer_extra_counters variable is align 16, size 16 to
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// ensure the padding between it and the next variable in this section (either
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// __libfuzzer_extra_counters or __stop___libfuzzer_extra_counters) will be
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// located at (__start___libfuzzer_extra_counters +
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// sizeof(__start___libfuzzer_extra_counters)). Otherwise, the calculation of
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// (stop - (start + sizeof(start))) might be skewed.
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//
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// The section name, __libfuzzer_extra_countaaa ends with "aaa", so it sorts
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// before __libfuzzer_extra_counters alphabetically. We want the start symbol to
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// be placed in the section just before the user supplied counters (if present).
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//
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#pragma section(".data$__libfuzzer_extra_countaaa")
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ATTRIBUTE_ALIGNED(16)
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__declspec(allocate(".data$__libfuzzer_extra_countaaa")) uint8_t
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__start___libfuzzer_extra_counters[16] = {0};
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//
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// Example of what the user-supplied counters should look like. First, the
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// pragma to create the section name. It will fall alphabetically between
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// ".data$__libfuzzer_extra_countaaa" and ".data$__libfuzzer_extra_countzzz".
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// Next, the declspec to allocate the variable inside the specified section.
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// Finally, some array, struct, whatever that is used to track the counter data.
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// The size of this variable is computed at runtime by finding the difference of
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// __stop___libfuzzer_extra_counters and __start___libfuzzer_extra_counters +
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// sizeof(__start___libfuzzer_extra_counters).
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//
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//
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// #pragma section(".data$__libfuzzer_extra_counters")
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// __declspec(allocate(".data$__libfuzzer_extra_counters"))
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// uint8_t any_name_variable[64 * 1024];
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//
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//
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// Here, the section name, __libfuzzer_extra_countzzz ends with "zzz", so it
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// sorts after __libfuzzer_extra_counters alphabetically. We want the stop
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// symbol to be placed in the section just after the user supplied counters (if
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// present). Align to 1 so there isn't any padding placed between this and the
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// previous variable.
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//
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#pragma section(".data$__libfuzzer_extra_countzzz")
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ATTRIBUTE_ALIGNED(1)
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__declspec(allocate(".data$__libfuzzer_extra_countzzz")) uint8_t
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__stop___libfuzzer_extra_counters = 0;
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uint8_t *ExtraCountersBegin() {
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return __start___libfuzzer_extra_counters +
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sizeof(__start___libfuzzer_extra_counters);
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}
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uint8_t *ExtraCountersEnd() { return &__stop___libfuzzer_extra_counters; }
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ATTRIBUTE_NO_SANITIZE_ALL
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void ClearExtraCounters() {
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uint8_t *Beg = ExtraCountersBegin();
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SecureZeroMemory(Beg, ExtraCountersEnd() - Beg);
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}
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} // namespace fuzzer
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#endif
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