libc/test/src/string/memory_utils/memory_check_utils.h

   1 //===-- Utils to test conformance of mem functions ------------------------===//
   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
   9 #ifndef LIBC_TEST_SRC_STRING_MEMORY_UTILS_MEMORY_CHECK_UTILS_H
  10 #define LIBC_TEST_SRC_STRING_MEMORY_UTILS_MEMORY_CHECK_UTILS_H
  11
  12 #include "src/__support/CPP/span.h"
  13 #include "src/__support/libc_assert.h" // LIBC_ASSERT
  14 #include "src/__support/macros/sanitizer.h"
  15 #include "src/string/memory_utils/utils.h"
  16 #include <stddef.h> // size_t
  17 #include <stdint.h> // uintxx_t
  18 #include <stdlib.h> // malloc/free
  19
  20 namespace LIBC_NAMESPACE {
  21
  22 // Simple structure to allocate a buffer of a particular size.
  23 // When ASAN is present it also poisons the whole memory.
  24 // This is a utility class to be used by Buffer below, do not use directly.
  25 struct PoisonedBuffer {
  26   PoisonedBuffer(size_t size) : ptr((char *)malloc(size)) {
  27     ASAN_POISON_MEMORY_REGION(ptr, size);
  28   }
  29   ~PoisonedBuffer() { free(ptr); }
  30
  31 protected:
  32   char *ptr = nullptr;
  33 };
  34
  35 // Simple structure to allocate a buffer (aligned or not) of a particular size.
  36 // It is backed by a wider buffer that is marked poisoned when ASAN is present.
  37 // The requested region is unpoisoned, this allows catching out of bounds
  38 // accesses.
  39 enum class Aligned : bool { NO = false, YES = true };
  40 struct Buffer : private PoisonedBuffer {
  41   static constexpr size_t kAlign = 64;
  42   static constexpr size_t kLeeway = 2 * kAlign;
  43   Buffer(size_t size, Aligned aligned = Aligned::YES)
  44       : PoisonedBuffer(size + kLeeway), size(size) {
  45     offset_ptr = ptr;
  46     offset_ptr += distance_to_next_aligned<kAlign>(ptr);
  47     if (aligned == Aligned::NO)
  48       ++offset_ptr;
  49     ASAN_UNPOISON_MEMORY_REGION(offset_ptr, size);
  50   }
  51   cpp::span<char> span() { return cpp::span<char>(offset_ptr, size); }
  52
  53 private:
  54   size_t size = 0;
  55   char *offset_ptr = nullptr;
  56 };
  57
  58 inline char GetRandomChar() {
  59   static constexpr const uint64_t a = 1103515245;
  60   static constexpr const uint64_t c = 12345;
  61   static constexpr const uint64_t m = 1ULL << 31;
  62   static uint64_t seed = 123456789;
  63   seed = (a * seed + c) % m;
  64   return static_cast<char>(seed);
  65 }
  66
  67 // Randomize the content of the buffer.
  68 inline void Randomize(cpp::span<char> buffer) {
  69   for (auto &current : buffer)
  70     current = GetRandomChar();
  71 }
  72
  73 // Copy one span to another.
  74 inline void ReferenceCopy(cpp::span<char> dst, const cpp::span<char> src) {
  75   for (size_t i = 0; i < dst.size(); ++i)
  76     dst[i] = src[i];
  77 }
  78
  79 inline bool IsEqual(const cpp::span<char> a, const cpp::span<char> b) {
  80   LIBC_ASSERT(a.size() == b.size());
  81   for (size_t i = 0; i < a.size(); ++i)
  82     if (a[i] != b[i])
  83       return false;
  84   return true;
  85 }
  86
  87 // Checks that FnImpl implements the memcpy semantic.
  88 template <auto FnImpl>
  89 inline bool CheckMemcpy(cpp::span<char> dst, cpp::span<char> src, size_t size) {
  90   Randomize(dst);
  91   FnImpl(dst, src, size);
  92   return IsEqual(dst, src);
  93 }
  94
  95 // Checks that FnImpl implements the memset semantic.
  96 template <auto FnImpl>
  97 inline bool CheckMemset(cpp::span<char> dst, uint8_t value, size_t size) {
  98   Randomize(dst);
  99   FnImpl(dst, value, size);
 100   for (char c : dst)
 101     if (c != (char)value)
 102       return false;
 103   return true;
 104 }
 105
 106 // Checks that FnImpl implements the bcmp semantic.
 107 template <auto FnImpl>
 108 inline bool CheckBcmp(cpp::span<char> span1, cpp::span<char> span2,
 109                       size_t size) {
 110   ReferenceCopy(span2, span1);
 111   // Compare equal
 112   if (int cmp = FnImpl(span1, span2, size); cmp != 0)
 113     return false;
 114   // Compare not equal if any byte differs
 115   for (size_t i = 0; i < size; ++i) {
 116     ++span2[i];
 117     if (int cmp = FnImpl(span1, span2, size); cmp == 0)
 118       return false;
 119     if (int cmp = FnImpl(span2, span1, size); cmp == 0)
 120       return false;
 121     --span2[i];
 122   }
 123   return true;
 124 }
 125
 126 // Checks that FnImpl implements the memcmp semantic.
 127 template <auto FnImpl>
 128 inline bool CheckMemcmp(cpp::span<char> span1, cpp::span<char> span2,
 129                         size_t size) {
 130   ReferenceCopy(span2, span1);
 131   // Compare equal
 132   if (int cmp = FnImpl(span1, span2, size); cmp != 0)
 133     return false;
 134   // Compare not equal if any byte differs
 135   for (size_t i = 0; i < size; ++i) {
 136     ++span2[i];
 137     int ground_truth = __builtin_memcmp(span1.data(), span2.data(), size);
 138     if (ground_truth > 0) {
 139       if (int cmp = FnImpl(span1, span2, size); cmp <= 0)
 140         return false;
 141       if (int cmp = FnImpl(span2, span1, size); cmp >= 0)
 142         return false;
 143     } else {
 144       if (int cmp = FnImpl(span1, span2, size); cmp >= 0)
 145         return false;
 146       if (int cmp = FnImpl(span2, span1, size); cmp <= 0)
 147         return false;
 148     }
 149     --span2[i];
 150   }
 151   return true;
 152 }
 153
 154 inline uint16_t Checksum(cpp::span<char> dst) {
 155   // We use Fletcher16 as it is trivial to implement.
 156   uint16_t sum1 = 0;
 157   uint16_t sum2 = 0;
 158   for (char c : dst) {
 159     sum1 = (sum1 + c) % 255U;
 160     sum2 = (sum2 + sum1) % 255U;
 161   }
 162   return static_cast<uint16_t>((sum2 << 8) | sum1);
 163 }
 164
 165 template <auto FnImpl>
 166 inline bool CheckMemmove(cpp::span<char> dst, cpp::span<char> src) {
 167   LIBC_ASSERT(dst.size() == src.size());
 168   // Memmove can override the src buffer. Technically we should save it into a
 169   // temporary buffer so we can check that 'dst' is equal to what 'src' was
 170   // before we called the function. To save on allocation and copy we use a
 171   // checksum instead.
 172   const auto src_checksum = Checksum(src);
 173   FnImpl(dst, src, dst.size());
 174   return Checksum(dst) == src_checksum;
 175 }
 176
 177 // Checks that FnImpl implements the memmove semantic.
 178 //  - Buffer size should be greater than 2 * size + 1.
 179 //  - Overlap refers to the number of bytes in common between the two buffers:
 180 //    - Negative means buffers are disjoint
 181 //    - zero mean they overlap exactly
 182 //  - Caller is responsible for randomizing the buffer.
 183 template <auto FnImpl>
 184 inline bool CheckMemmove(cpp::span<char> buffer, size_t size, int overlap) {
 185   LIBC_ASSERT(buffer.size() > (2 * size + 1));
 186   const size_t half_size = buffer.size() / 2;
 187   LIBC_ASSERT((size_t)(overlap >= 0 ? overlap : -overlap) < half_size);
 188   cpp::span<char> head = buffer.first(half_size + overlap).last(size);
 189   cpp::span<char> tail = buffer.last(half_size).first(size);
 190   LIBC_ASSERT(head.size() == size);
 191   LIBC_ASSERT(tail.size() == size);
 192   // dst before src
 193   if (!CheckMemmove<FnImpl>(head, tail))
 194     return false;
 195   // dst after src
 196   if (!CheckMemmove<FnImpl>(tail, head))
 197     return false;
 198   return true;
 199 }
 200
 201 } // namespace LIBC_NAMESPACE
 202
 203 #endif // LIBC_TEST_SRC_STRING_MEMORY_UTILS_MEMORY_CHECK_UTILS_H