Sync with upstream repo.

Changes include:
* CPU check has been broken up into a number of small libraries
* BoringSSL option has been removed
* Better abseil integration

malign_buffer.h

@@ -0,0 +1,124 @@
+// Copyright 2020 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef THIRD_PARTY_CPU_CHECK_MALIGN_BUFFER_H_
+#define THIRD_PARTY_CPU_CHECK_MALIGN_BUFFER_H_
+
+#include <random>
+#include <string>
+
+#include "absl/strings/string_view.h"
+
+namespace cpu_check {
+
+// Data buffer supporting various alignments, copy mechanisms, and verification
+// methods.
+class MalignBuffer {
+ public:
+  struct PunchedHole {
+    std::string ToString() const;
+    size_t start = 0;
+    size_t length = 0;
+    unsigned char v = 0x53;
+  };
+
+  enum CopyMethod {
+    kMemcpy,
+    kRepMov,
+    kSseBy128,
+    kAvxBy256,
+    kAvxBy512,
+  };
+
+  // Returns name of given CopyMethod.
+  static std::string ToString(CopyMethod m);
+
+  static const size_t kPageSize;
+  static const size_t kCacheLineSize;
+
+  // Returns a random alignment offset in range [0..kPageSize-1].
+  static size_t RandomAlignment(uint64_t seed);
+
+  // Helper to make MSAN happy. NOP if memory sanitizer is not enabled.
+  static void InitializeMemoryForSanitizer(char* addr, size_t size);
+
+  // Constructs MalignBuffer of specified capacity.
+  MalignBuffer(size_t capacity);
+
+  // Constructs and initializes MalignBuffer with specified alignment and
+  // content. Useful for unit tests.
+  // REQUIRES:
+  //   alignment_offset < kPageSize
+  MalignBuffer(size_t alignment_offset, absl::string_view s);
+
+  ~MalignBuffer();
+
+  // Initializes buffer to specified alignment.
+  // REQUIRES:
+  //   alignment_offset < kPageSize
+  //   length <= this.capacity_.
+  void Initialize(size_t alignment_offset, size_t length);
+
+  const char* data() const { return buffer_address_; }
+  char* data() { return buffer_address_; }
+  size_t size() const { return length_; }
+
+  // REQUIRES length <= capacity_.
+  void resize(size_t length);
+
+  // Compares 'this' to 'that' returning empty string if identical.
+  // If not identical, returns a syndrome, currently Hamming distance,
+  // corrupted subrange bounds, and the diffs.
+  std::string Syndrome(const MalignBuffer& that) const;
+
+  // Validated data copy from source to 'this'.
+  // 'this' must be appropriately sized.
+  // Returns syndrome upon copy failure.
+  std::string CopyFrom(const MalignBuffer& that, CopyMethod m);
+
+  // Unvalidated copy to 'this'.
+  void CopyFrom(absl::string_view src, CopyMethod m);
+  void CopyFrom(size_t pos, absl::string_view src, CopyMethod m);
+
+  // Randomly flushes cache lines.
+  void RandomFlush(std::knuth_b* rng) const;
+
+  // Conventional or rep;sto memset operation, according to 'use_rep_stos'.
+  void Memset(size_t offset, unsigned char v, size_t length, bool use_rep_stos);
+
+  // Memsets buffer to 'hole.v', using rep;stos operation if
+  // 'use_rep_stos' set;
+  void PunchHole(const PunchedHole& hole, bool use_rep_stos);
+
+  // Hints to the OS to release the buffer's memory.
+  void MadviseDontNeed() const;
+
+  // Returns random PunchedHole within 'this'.
+  MalignBuffer::PunchedHole RandomPunchedHole(uint64_t seed) const;
+
+ private:
+  static size_t RoundUpToPageSize(size_t k);
+  std::string CorruptionSyndrome(const MalignBuffer& that) const;
+  std::string CrackId(uint64_t) const;
+
+  const size_t capacity_;
+  void* base_address_ = nullptr;
+
+  size_t alignment_offset_ = 0;
+  size_t length_ = 0;  // Usable length
+  char* buffer_address_ = nullptr;
+};
+
+}  // namespace cpu_check
+#endif  // THIRD_PARTY_CPU_CHECK_MALIGN_BUFFER_H_