tools/fuzzing/libfuzzer/FuzzerExtraCounters.cpp

   1 //===- FuzzerExtraCounters.cpp - Extra coverage counters ------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 // Extra coverage counters defined by user code.
   9 //===----------------------------------------------------------------------===//
  10
  11 #include "FuzzerPlatform.h"
  12 #include <cstdint>
  13
  14 #if LIBFUZZER_LINUX || LIBFUZZER_NETBSD || LIBFUZZER_FREEBSD ||                \
  15     LIBFUZZER_OPENBSD || LIBFUZZER_FUCHSIA || LIBFUZZER_EMSCRIPTEN
  16 __attribute__((weak)) extern uint8_t __start___libfuzzer_extra_counters;
  17 __attribute__((weak)) extern uint8_t __stop___libfuzzer_extra_counters;
  18
  19 namespace fuzzer {
  20 uint8_t *ExtraCountersBegin() { return &__start___libfuzzer_extra_counters; }
  21 uint8_t *ExtraCountersEnd() { return &__stop___libfuzzer_extra_counters; }
  22 ATTRIBUTE_NO_SANITIZE_ALL
  23 void ClearExtraCounters() {  // hand-written memset, don't asan-ify.
  24   uintptr_t *Beg = reinterpret_cast<uintptr_t*>(ExtraCountersBegin());
  25   uintptr_t *End = reinterpret_cast<uintptr_t*>(ExtraCountersEnd());
  26   for (; Beg < End; Beg++) {
  27     *Beg = 0;
  28     __asm__ __volatile__("" : : : "memory");
  29   }
  30 }
  31
  32 }  // namespace fuzzer
  33
  34 #else
  35 // TODO: implement for other platforms.
  36 namespace fuzzer {
  37 uint8_t *ExtraCountersBegin() { return nullptr; }
  38 uint8_t *ExtraCountersEnd() { return nullptr; }
  39 void ClearExtraCounters() {}
  40 }  // namespace fuzzer
  41
  42 #endif