Commit 881faf41 authored by Matt Morehouse's avatar Matt Morehouse
Browse files

Enable extra coverage counters on Windows 

- Enable extra coverage counters on Windows.
- Update extra_counters.test to run on Windows also.
- Update TableLookupTest.cpp to include the required pragma/declspec for the extra coverage counters.

Patch By: MichaelSquires

Reviewed By: morehouse

Differential Revision: https://reviews.llvm.org/D106676
parent 892990c5

compiler-rt/lib/fuzzer/CMakeLists.txt

+2 −0
Original line number Diff line number Diff line
@@ -6,6 +6,8 @@ set(LIBFUZZER_SOURCES 
  FuzzerExtFunctionsWeak.cpp

  FuzzerExtFunctionsWindows.cpp

  FuzzerExtraCounters.cpp

  FuzzerExtraCountersDarwin.cpp

  FuzzerExtraCountersWindows.cpp

  FuzzerFork.cpp

  FuzzerIO.cpp

  FuzzerIOPosix.cpp

compiler-rt/lib/fuzzer/FuzzerExtraCounters.cpp

+0 −8
Original line number Diff line number Diff line
@@ -31,12 +31,4 @@ void ClearExtraCounters() { // hand-written memset, don't asan-ify. 


}  // namespace fuzzer



#else

// TODO: implement for other platforms.

namespace fuzzer {

uint8_t *ExtraCountersBegin() { return nullptr; }

uint8_t *ExtraCountersEnd() { return nullptr; }

void ClearExtraCounters() {}

}  // namespace fuzzer



#endif

compiler-rt/lib/fuzzer/FuzzerExtraCountersDarwin.cpp

0 → 100644
+21 −0
Original line number Diff line number Diff line 
//===- FuzzerExtraCountersDarwin.cpp - Extra coverage counters for Darwin -===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

// Extra coverage counters defined by user code for Darwin.

//===----------------------------------------------------------------------===//



#include "FuzzerPlatform.h"



#if LIBFUZZER_APPLE



namespace fuzzer {

uint8_t *ExtraCountersBegin() { return nullptr; }

uint8_t *ExtraCountersEnd() { return nullptr; }

void ClearExtraCounters() {}

} // namespace fuzzer



#endif

compiler-rt/lib/fuzzer/FuzzerExtraCountersWindows.cpp

0 → 100644
+80 −0
Original line number Diff line number Diff line 
//===- FuzzerExtraCountersWindows.cpp - Extra coverage counters for Win32 -===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

// Extra coverage counters defined by user code for Windows.

//===----------------------------------------------------------------------===//



#include "FuzzerPlatform.h"

#include <cstdint>



#if LIBFUZZER_WINDOWS

#include <Windows.h>



namespace fuzzer {



//

// The __start___libfuzzer_extra_counters variable is align 16, size 16 to

// ensure the padding between it and the next variable in this section (either

// __libfuzzer_extra_counters or __stop___libfuzzer_extra_counters) will be

// located at (__start___libfuzzer_extra_counters +

// sizeof(__start___libfuzzer_extra_counters)). Otherwise, the calculation of

// (stop - (start + sizeof(start))) might be skewed.

//

// The section name, __libfuzzer_extra_countaaa ends with "aaa", so it sorts

// before __libfuzzer_extra_counters alphabetically. We want the start symbol to

// be placed in the section just before the user supplied counters (if present).

//

#pragma section(".data$__libfuzzer_extra_countaaa")

ATTRIBUTE_ALIGNED(16)

__declspec(allocate(".data$__libfuzzer_extra_countaaa")) uint8_t

    __start___libfuzzer_extra_counters[16] = {0};



//

// Example of what the user-supplied counters should look like. First, the

// pragma to create the section name. It will fall alphabetically between

// ".data$__libfuzzer_extra_countaaa" and ".data$__libfuzzer_extra_countzzz".

// Next, the declspec to allocate the variable inside the specified section.

// Finally, some array, struct, whatever that is used to track the counter data.

// The size of this variable is computed at runtime by finding the difference of

// __stop___libfuzzer_extra_counters and __start___libfuzzer_extra_counters +

// sizeof(__start___libfuzzer_extra_counters).

//



//

//     #pragma section(".data$__libfuzzer_extra_counters")

//     __declspec(allocate(".data$__libfuzzer_extra_counters"))

//         uint8_t any_name_variable[64 * 1024];

//



//

// Here, the section name, __libfuzzer_extra_countzzz ends with "zzz", so it

// sorts after __libfuzzer_extra_counters alphabetically. We want the stop

// symbol to be placed in the section just after the user supplied counters (if

// present). Align to 1 so there isn't any padding placed between this and the

// previous variable.

//

#pragma section(".data$__libfuzzer_extra_countzzz")

ATTRIBUTE_ALIGNED(1)

__declspec(allocate(".data$__libfuzzer_extra_countzzz")) uint8_t

    __stop___libfuzzer_extra_counters = 0;



uint8_t *ExtraCountersBegin() {

  return __start___libfuzzer_extra_counters +

         sizeof(__start___libfuzzer_extra_counters);

}



uint8_t *ExtraCountersEnd() { return &__stop___libfuzzer_extra_counters; }



ATTRIBUTE_NO_SANITIZE_ALL

void ClearExtraCounters() {

  uint8_t *Beg = ExtraCountersBegin();

  SecureZeroMemory(Beg, ExtraCountersEnd() - Beg);

}



} // namespace fuzzer



#endif

compiler-rt/test/fuzzer/TableLookupTest.cpp

+5 −1
Original line number Diff line number Diff line
@@ -24,6 +24,10 @@ const size_t N = 1 << 12; 
// is important to distinguish from one occurrence.

#ifdef __linux__

__attribute__((section("__libfuzzer_extra_counters")))

#endif

#ifdef _WIN32

#  pragma section(".data$__libfuzzer_extra_counters")

__declspec(allocate(".data$__libfuzzer_extra_counters"))

#endif

    static uint8_t Counters[N];