[hwasan] Record and display stack history in stack-based reports.
Summary:
Display a list of recent stack frames (not a stack trace!) when
tag-mismatch is detected on a stack address.
The implementation uses alignment tricks to get both the address of
the history buffer, and the base address of the shadow with a single
8-byte load. See the comment in hwasan_thread_list.h for more
details.
Developed in collaboration with Kostya Serebryany.
Reviewers: kcc
Subscribers: srhines, kubamracek, mgorny, hiraditya, jfb, llvm-commits
Differential Revision: https://reviews.llvm.org/D52249
llvm-svn: 342923
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_ring_buffer.h b/compiler-rt/lib/sanitizer_common/sanitizer_ring_buffer.h
index c4649c2..d15f27f 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_ring_buffer.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_ring_buffer.h
@@ -72,12 +72,91 @@
// L: last_, always points to the last data element.
// N: next_, initially equals to last_, is decremented on every push,
// wraps around if it's less or equal than its own address.
-
T *last_;
T *next_;
T data_[1]; // flexible array.
};
+// A ring buffer with externally provided storage that encodes its state in 8
+// bytes. Has significant constraints on size and alignment of storage.
+// See a comment in hwasan/hwasan_thread_list.h for the motivation behind this.
+#if SANITIZER_WORDSIZE == 64
+template <class T>
+class CompactRingBuffer {
+ // Top byte of long_ stores the buffer size in pages.
+ // Lower bytes store the address of the next buffer element.
+ static constexpr int kPageSizeBits = 12;
+ static constexpr int kSizeShift = 56;
+ static constexpr uptr kNextMask = (1ULL << kSizeShift) - 1;
+
+ uptr GetStorageSize() const { return (long_ >> kSizeShift) << kPageSizeBits; }
+
+ void Init(void *storage, uptr size) {
+ CHECK_EQ(sizeof(CompactRingBuffer<T>), sizeof(void *));
+ CHECK(IsPowerOfTwo(size));
+ CHECK_GE(size, 1 << kPageSizeBits);
+ CHECK_LE(size, 128 << kPageSizeBits);
+ CHECK_EQ(size % 4096, 0);
+ CHECK_EQ(size % sizeof(T), 0);
+ CHECK_EQ((uptr)storage % (size * 2), 0);
+ long_ = (uptr)storage | ((size >> kPageSizeBits) << kSizeShift);
+ }
+
+ void SetNext(const T *next) {
+ long_ = (long_ & ~kNextMask) | (uptr)next;
+ }
+
+ public:
+ CompactRingBuffer(void *storage, uptr size) {
+ Init(storage, size);
+ }
+
+ // A copy constructor of sorts.
+ CompactRingBuffer(const CompactRingBuffer &other, void *storage) {
+ uptr size = other.GetStorageSize();
+ internal_memcpy(storage, other.StartOfStorage(), size);
+ Init(storage, size);
+ uptr Idx = other.Next() - (const T *)other.StartOfStorage();
+ SetNext((const T *)storage + Idx);
+ }
+
+ T *Next() const { return (T *)(long_ & kNextMask); }
+
+ void *StartOfStorage() const {
+ return (void *)((uptr)Next() & ~(GetStorageSize() - 1));
+ }
+
+ void *EndOfStorage() const {
+ return (void *)((uptr)StartOfStorage() + GetStorageSize());
+ }
+
+ uptr size() const { return GetStorageSize() / sizeof(T); }
+
+ void push(T t) {
+ T *next = Next();
+ *next = t;
+ next++;
+ next = (T *)((uptr)next & ~GetStorageSize());
+ SetNext(next);
+ }
+
+ T operator[](uptr Idx) const {
+ CHECK_LT(Idx, size());
+ const T *Begin = (const T *)StartOfStorage();
+ sptr StorageIdx = Next() - Begin;
+ StorageIdx -= (sptr)(Idx + 1);
+ if (StorageIdx < 0)
+ StorageIdx += size();
+ return Begin[StorageIdx];
+ }
+
+ public:
+ ~CompactRingBuffer() {}
+ CompactRingBuffer(const CompactRingBuffer &) = delete;
+
+ uptr long_;
+};
+#endif
} // namespace __sanitizer
#endif // SANITIZER_RING_BUFFER_H
diff --git a/compiler-rt/lib/sanitizer_common/tests/sanitizer_ring_buffer_test.cc b/compiler-rt/lib/sanitizer_common/tests/sanitizer_ring_buffer_test.cc
index a9286ce..80aa57c 100644
--- a/compiler-rt/lib/sanitizer_common/tests/sanitizer_ring_buffer_test.cc
+++ b/compiler-rt/lib/sanitizer_common/tests/sanitizer_ring_buffer_test.cc
@@ -66,6 +66,7 @@
#undef EXPECT_RING_BUFFER
}
+#if SANITIZER_WORDSIZE == 64
TEST(RingBuffer, int64) {
TestRB<int64_t>();
}
@@ -74,4 +75,25 @@
TestRB<LargeStruct>();
}
+template<typename T>
+CompactRingBuffer<T> *AllocCompactRingBuffer(size_t count) {
+ size_t sz = sizeof(T) * count;
+ EXPECT_EQ(0ULL, sz % 4096);
+ void *p = MmapAlignedOrDieOnFatalError(sz, sz * 2, "CompactRingBuffer");
+ return new CompactRingBuffer<T>(p, sz);
+}
+
+TEST(CompactRingBuffer, int64) {
+ const size_t page_sizes[] = {1, 2, 4, 128};
+
+ for (size_t pages : page_sizes) {
+ size_t count = 4096 * pages / sizeof(int64_t);
+ auto R = AllocCompactRingBuffer<int64_t>(count);
+ int64_t top = count * 3 + 13;
+ for (int64_t i = 0; i < top; ++i) R->push(i);
+ for (int64_t i = 0; i < (int64_t)count; ++i)
+ EXPECT_EQ(top - i - 1, (*R)[i]);
+ }
+}
+#endif
} // namespace __sanitizer