[scudo] Add memtag_test

[hctim]

compiler-rt/lib/scudo/standalone/tests/memtag_test.cpp

50

Should we restore to the previous MTE mode (SYNC/ASYNC) instead of just turning it to SYNC?

100

It wasn't obvious to me on first glance why *P was a deterministic fault. Might be worth adding a comment to selectRandomTag that tag zero is excluded from when the prctl was issued.

105

Wouldn't we want to die if the prctl failed?

152

Untag after test?

173

Implicit invariant that 0x100 >= 4 * archMemoryTagGranuleSize(). Maybe make it explicit?

uptr WorkingRegionSize = 4 * archMemoryTagGranuleSize();
for (uptr Size = 0; Size < WorkingRegionSize; ++Size, P += WorkingRegionSize) {

[pcc]

compiler-rt/lib/scudo/standalone/memtag.h

160

This isn't necessary, the caller should do that themselves.

compiler-rt/lib/scudo/standalone/tests/memtag_test.cpp

51

We normally handle this by skipping the tests if the system isn't detecting tag faults. Can we set the tagging mode in the main function? That way, both these tests and the combined allocator tests should run.

103

We have ScopedDisableMemoryTagChecks for this purpose.

[vitalybuka]

updates

[vitalybuka]

compiler-rt/lib/scudo/standalone/memtag.h

160

DCHECK?

compiler-rt/lib/scudo/standalone/tests/memtag_test.cpp

50

going with main() function, so nothing to restore

100

And removing 0 from prctl does not look nice.
I don't need selectRandomTag here anyway.

103

That one uses TSO, here I tests prctl.
I may use ScopedDisableMemoryTagChecks in the next test,
however ScopedDisableMemoryTagChecks is unused in the code, so maybe we should remove it at all?

152

::TearDown munpap entire buffer

[vitalybuka]

ping

[hctim]

LGTM, but WANT_LGTM=pcc.

[pcc]

compiler-rt/lib/scudo/standalone/tests/memtag_test.cpp

103

The {disable,enable}MemoryTagChecksTestOnly functions use TCO, same as ScopedDisableMemoryTagChecks. There's a use of ScopedDisableMemoryTagChecks in combined.h and we could probably start using ScopedDisableMemoryTagChecks in combined_test.cpp which would let us remove {disable,enable}MemoryTagChecksTestOnly.

[vitalybuka]

Removed MemoryTagChecksTestOnly test

[pcc]

LGTM

[hubert.reinterpretcast]

This is causing failures https://lab.llvm.org/buildbot/#/builders/57/builds/7002/steps/6/logs/stdio:

/home/buildbots/docker-RHEL-buildbot/SetupBot/worker_env/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/utils/unittest/googletest/include/gtest/gtest.h:1527:11: error: comparison of integers of different signs: 'const int' and 'const unsigned long' [-Werror,-Wsign-compare]
  if (lhs == rhs) {
      ~~~ ^  ~~~
/home/buildbots/docker-RHEL-buildbot/SetupBot/worker_env/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/utils/unittest/googletest/include/gtest/gtest.h:1554:12: note: in instantiation of function template specialization 'testing::internal::CmpHelperEQ<int, unsigned long>' requested here
    return CmpHelperEQ(lhs_expression, rhs_expression, lhs, rhs);
           ^
/home/buildbots/docker-RHEL-buildbot/SetupBot/worker_env/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/compiler-rt/lib/scudo/standalone/tests/memtag_test.cpp:77:3: note: in instantiation of function template specialization 'testing::internal::EqHelper::Compare<int, unsigned long, nullptr>' requested here
  EXPECT_EQ(0xffff, Tags);
  ^
/home/buildbots/docker-RHEL-buildbot/SetupBot/worker_env/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/utils/unittest/googletest/include/gtest/gtest.h:2028:54: note: expanded from macro 'EXPECT_EQ'
  EXPECT_PRED_FORMAT2(::testing::internal::EqHelper::Compare, val1, val2)
                                                     ^
1 error generated.

[pcc]

compiler-rt/lib/scudo/standalone/tests/memtag_test.cpp

14

Why do we need this? The tests should all fail to detect MTE on non-Linux platforms, shouldn't they?

[vitalybuka]

compiler-rt/lib/scudo/standalone/tests/memtag_test.cpp

14

it uses GTEST stuff which is likely not available on zxtest of Fucsia

compiler-rt/lib/scudo/standalone/memtag.h

__asm__ __volatile__(
       )"
       : [TaggedPtr] "=r"(TaggedPtr)
       : [Ptr] "r"(Ptr), [ExcludeMask] "r"(ExcludeMask));
   return TaggedPtr;
 }
 
 inline uptr addFixedTag(uptr Ptr, uptr Tag) {
   DCHECK_LT(Tag, 16);
+  DCHECK_EQ(untagPointer(Ptr), Ptr);
   return Ptr | (Tag << 56);
 }
 
 inline uptr storeTags(uptr Begin, uptr End) {
   DCHECK_EQ(0, Begin % 16);
   uptr LineSize, Next, Tmp;
   __asm__ __volatile__(
       R"(
     .arch_extension memtag

compiler-rt/lib/scudo/standalone/tests/CMakeLists.txt

set(SCUDO_UNIT_TEST_SOURCES
   bytemap_test.cpp
   checksum_test.cpp
   chunk_test.cpp
   combined_test.cpp
   common_test.cpp
   flags_test.cpp
   list_test.cpp
   map_test.cpp
+  memtag_test.cpp
   mutex_test.cpp
   primary_test.cpp
   quarantine_test.cpp
   release_test.cpp
   report_test.cpp
   secondary_test.cpp
   size_class_map_test.cpp
   stats_test.cpp

compiler-rt/lib/scudo/standalone/tests/memtag_test.cpp

+//===-- memtag_test.cpp -----------------------------------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "common.h"
+#include "memtag.h"
+#include "platform.h"
+#include "tests/scudo_unit_test.h"
+
+#if SCUDO_LINUX
+namespace scudo {
+
+TEST(MemtagBasicTest, Unsupported) {
+  if (archSupportsMemoryTagging())
+    GTEST_SKIP();
+
+  EXPECT_DEATH(archMemoryTagGranuleSize(), "not supported");
+  EXPECT_DEATH(untagPointer((uptr)0), "not supported");
+  EXPECT_DEATH(extractTag((uptr)0), "not supported");
+
+  EXPECT_DEATH(systemSupportsMemoryTagging(), "not supported");
+  EXPECT_DEATH(systemDetectsMemoryTagFaultsTestOnly(), "not supported");
+  EXPECT_DEATH(enableSystemMemoryTaggingTestOnly(), "not supported");
+
+  EXPECT_DEATH(selectRandomTag((uptr)0, 0), "not supported");
+  EXPECT_DEATH(addFixedTag((uptr)0, 1), "not supported");
+  EXPECT_DEATH(storeTags((uptr)0, (uptr)0 + sizeof(0)), "not supported");
+  EXPECT_DEATH(storeTag((uptr)0), "not supported");
+  EXPECT_DEATH(loadTag((uptr)0), "not supported");
+
+  EXPECT_DEATH(setRandomTag(nullptr, 64, 0, nullptr, nullptr), "not supported");
+  EXPECT_DEATH(untagPointer(nullptr), "not supported");
+  EXPECT_DEATH(loadTag(nullptr), "not supported");
+  EXPECT_DEATH(addFixedTag(nullptr, 0), "not supported");
+}
+
+class MemtagTest : public ::testing::Test {
+protected:
+  void SetUp() override {
+    if (!archSupportsMemoryTagging() || !systemDetectsMemoryTagFaultsTestOnly())
+      GTEST_SKIP() << "Memory tagging is not supported";
+
+    BufferSize = getPageSizeCached();
+    Buffer = reinterpret_cast<u8 *>(
+        map(nullptr, BufferSize, "MemtagTest", MAP_MEMTAG, &Data));
+    Addr = reinterpret_cast<uptr>(Buffer);
+    EXPECT_TRUE(isAligned(Addr, archMemoryTagGranuleSize()));
+    EXPECT_EQ(Addr, untagPointer(Addr));
+  }
+
+  void TearDown() override {
+    if (Buffer)
+      unmap(Buffer, BufferSize, 0, &Data);
+  }
+
+  uptr BufferSize = 0;
+  MapPlatformData Data = {};
+  u8 *Buffer = nullptr;
+  uptr Addr = 0;
+};
+
+TEST_F(MemtagTest, ArchMemoryTagGranuleSize) {
+  EXPECT_GT(archMemoryTagGranuleSize(), 1u);
+  EXPECT_TRUE(isPowerOfTwo(archMemoryTagGranuleSize()));
+}
+
+TEST_F(MemtagTest, ExtractTag) {
+  uptr Tags = 0;
+  // Try all value for the top byte and check the tags values are in the
+  // expected range.
+  for (u64 Top = 0; Top < 0x100; ++Top)
+    Tags = Tags | (1u << extractTag(Addr | (Top << 56)));
+  EXPECT_EQ(0xffff, Tags);
+}
+
+TEST_F(MemtagTest, AddFixedTag) {
+  for (uptr Tag = 0; Tag < 0x10; ++Tag)
+    EXPECT_EQ(Tag, extractTag(addFixedTag(Addr, Tag)));
+  if (SCUDO_DEBUG) {
+    EXPECT_DEBUG_DEATH(addFixedTag(Addr, 16), "");
+    EXPECT_DEBUG_DEATH(addFixedTag(~Addr, 0), "");
+  }
+}
+
+TEST_F(MemtagTest, UntagPointer) {
+  uptr UnTagMask = untagPointer(~uptr(0));
+  for (u64 Top = 0; Top < 0x100; ++Top) {
+    uptr Ptr = (Addr | (Top << 56)) & UnTagMask;
+    EXPECT_EQ(addFixedTag(Ptr, 0), untagPointer(Ptr));
+  }
+}
+
+TEST_F(MemtagTest, ScopedDisableMemoryTagChecks) {
+  u8 *P = reinterpret_cast<u8 *>(addFixedTag(Addr, 1));
+  EXPECT_NE(P, Buffer);
+
+  EXPECT_DEATH(*P = 20, "");
+  ScopedDisableMemoryTagChecks Disable;
+  *P = 10;
+}
+
+TEST_F(MemtagTest, SelectRandomTag) {
+  for (uptr SrcTag = 0; SrcTag < 0x10; ++SrcTag) {
+    uptr Ptr = addFixedTag(Addr, SrcTag);
+    uptr Tags = 0;
+    for (uptr I = 0; I < 100000; ++I)
+      Tags = Tags | (1u << extractTag(selectRandomTag(Ptr, 0)));
+    EXPECT_EQ(0xfffe, Tags);
+  }
+}
+
+TEST_F(MemtagTest, SelectRandomTagWithMask) {
+  for (uptr j = 0; j < 32; ++j) {
+    for (uptr i = 0; i < 1000; ++i)
+      EXPECT_NE(j, extractTag(selectRandomTag(Addr, 1ull << j)));
+  }
+}
+
+TEST_F(MemtagTest, SKIP_NO_DEBUG(LoadStoreTagUnaligned)) {
+  for (uptr P = Addr; P < Addr + 4 * archMemoryTagGranuleSize(); ++P) {
+    if (P % archMemoryTagGranuleSize() == 0)
+      continue;
+    EXPECT_DEBUG_DEATH(loadTag(P), "");
+    EXPECT_DEBUG_DEATH(storeTag(P), "");
+  }
+}
+
+TEST_F(MemtagTest, LoadStoreTag) {
+  uptr Base = Addr + 0x100;
+  uptr Tagged = addFixedTag(Base, 7);
+  storeTag(Tagged);
+
+  EXPECT_EQ(Base - archMemoryTagGranuleSize(),
+            loadTag(Base - archMemoryTagGranuleSize()));
+  EXPECT_EQ(Tagged, loadTag(Base));
+  EXPECT_EQ(Base + archMemoryTagGranuleSize(),
+            loadTag(Base + archMemoryTagGranuleSize()));
+}
+
+TEST_F(MemtagTest, SKIP_NO_DEBUG(StoreTagsUnaligned)) {
+  for (uptr P = Addr; P < Addr + 4 * archMemoryTagGranuleSize(); ++P) {
+    uptr Tagged = addFixedTag(P, 5);
+    if (Tagged % archMemoryTagGranuleSize() == 0)
+      continue;
+    EXPECT_DEBUG_DEATH(storeTags(Tagged, Tagged), "");
+  }
+}
+
+TEST_F(MemtagTest, StoreTags) {
+  const uptr MaxTaggedSize = 4 * archMemoryTagGranuleSize();
+  for (uptr Size = 0; Size <= MaxTaggedSize; ++Size) {
+    uptr NoTagBegin = Addr + archMemoryTagGranuleSize();
+    uptr NoTagEnd = NoTagBegin + Size;
+
+    u8 Tag = 5;
+
+    uptr TaggedBegin = addFixedTag(NoTagBegin, Tag);
+    uptr TaggedEnd = addFixedTag(NoTagEnd, Tag);
+
+    EXPECT_EQ(roundUpTo(TaggedEnd, archMemoryTagGranuleSize()),
+              storeTags(TaggedBegin, TaggedEnd));
+
+    uptr LoadPtr = Addr;
+    // Untagged left granule.
+    EXPECT_EQ(LoadPtr, loadTag(LoadPtr));
+
+    for (LoadPtr += archMemoryTagGranuleSize(); LoadPtr < NoTagEnd;
+         LoadPtr += archMemoryTagGranuleSize()) {
+      EXPECT_EQ(addFixedTag(LoadPtr, 5), loadTag(LoadPtr));
+    }
+
+    // Untagged right granule.
+    EXPECT_EQ(LoadPtr, loadTag(LoadPtr));
+
+    // Reset tags without using StoreTags.
+    releasePagesToOS(Addr, 0, BufferSize, &Data);
+  }
+}
+
+} // namespace scudo
+
+#endif

compiler-rt/lib/scudo/standalone/tests/scudo_unit_test.h

 #endif
 
 #if SCUDO_FUCHSIA
 #define SKIP_ON_FUCHSIA(T) DISABLED_##T
 #else
 #define SKIP_ON_FUCHSIA(T) T
 #endif
 
+#if SCUDO_DEBUG
+#define SKIP_NO_DEBUG(T) T
+#else
+#define SKIP_NO_DEBUG(T) DISABLED_##T
+#endif
+
 extern bool UseQuarantine;