lib/XRay/FDRRecordProducer.cpp

   1 //===- FDRRecordProducer.cpp - XRay FDR Mode Record Producer --------------===//
   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 #include "llvm/XRay/FDRRecordProducer.h"
   9 #include "llvm/Support/DataExtractor.h"
  10
  11 #include <cstdint>
  12
  13 namespace llvm {
  14 namespace xray {
  15
  16 namespace {
  17
  18 // Keep this in sync with the values written in the XRay FDR mode runtime in
  19 // compiler-rt.
  20 enum MetadataRecordKinds : uint8_t {
  21   NewBufferKind,
  22   EndOfBufferKind,
  23   NewCPUIdKind,
  24   TSCWrapKind,
  25   WalltimeMarkerKind,
  26   CustomEventMarkerKind,
  27   CallArgumentKind,
  28   BufferExtentsKind,
  29   TypedEventMarkerKind,
  30   PidKind,
  31   // This is an end marker, used to identify the upper bound for this enum.
  32   EnumEndMarker,
  33 };
  34
  35 Expected<std::unique_ptr<Record>>
  36 metadataRecordType(const XRayFileHeader &Header, uint8_t T) {
  37
  38   if (T >= static_cast<uint8_t>(MetadataRecordKinds::EnumEndMarker))
  39     return createStringError(std::make_error_code(std::errc::invalid_argument),
  40                              "Invalid metadata record type: %d", T);
  41   switch (T) {
  42   case MetadataRecordKinds::NewBufferKind:
  43     return make_unique<NewBufferRecord>();
  44   case MetadataRecordKinds::EndOfBufferKind:
  45     if (Header.Version >= 2)
  46       return createStringError(
  47           std::make_error_code(std::errc::executable_format_error),
  48           "End of buffer records are no longer supported starting version "
  49           "2 of the log.");
  50     return make_unique<EndBufferRecord>();
  51   case MetadataRecordKinds::NewCPUIdKind:
  52     return make_unique<NewCPUIDRecord>();
  53   case MetadataRecordKinds::TSCWrapKind:
  54     return make_unique<TSCWrapRecord>();
  55   case MetadataRecordKinds::WalltimeMarkerKind:
  56     return make_unique<WallclockRecord>();
  57   case MetadataRecordKinds::CustomEventMarkerKind:
  58     if (Header.Version >= 5)
  59       return make_unique<CustomEventRecordV5>();
  60     return make_unique<CustomEventRecord>();
  61   case MetadataRecordKinds::CallArgumentKind:
  62     return make_unique<CallArgRecord>();
  63   case MetadataRecordKinds::BufferExtentsKind:
  64     return make_unique<BufferExtents>();
  65   case MetadataRecordKinds::TypedEventMarkerKind:
  66     return make_unique<TypedEventRecord>();
  67   case MetadataRecordKinds::PidKind:
  68     return make_unique<PIDRecord>();
  69   case MetadataRecordKinds::EnumEndMarker:
  70     llvm_unreachable("Invalid MetadataRecordKind");
  71   }
  72   llvm_unreachable("Unhandled MetadataRecordKinds enum value");
  73 }
  74
  75 constexpr bool isMetadataIntroducer(uint8_t FirstByte) {
  76   return FirstByte & 0x01u;
  77 }
  78
  79 } // namespace
  80
  81 Expected<std::unique_ptr<Record>>
  82 FileBasedRecordProducer::findNextBufferExtent() {
  83   // We seek one byte at a time until we find a suitable buffer extents metadata
  84   // record introducer.
  85   std::unique_ptr<Record> R;
  86   while (!R) {
  87     auto PreReadOffset = OffsetPtr;
  88     uint8_t FirstByte = E.getU8(&OffsetPtr);
  89     if (OffsetPtr == PreReadOffset)
  90       return createStringError(
  91           std::make_error_code(std::errc::executable_format_error),
  92           "Failed reading one byte from offset %d.", OffsetPtr);
  93
  94     if (isMetadataIntroducer(FirstByte)) {
  95       auto LoadedType = FirstByte >> 1;
  96       if (LoadedType == MetadataRecordKinds::BufferExtentsKind) {
  97         auto MetadataRecordOrErr = metadataRecordType(Header, LoadedType);
  98         if (!MetadataRecordOrErr)
  99           return MetadataRecordOrErr.takeError();
 100
 101         R = std::move(MetadataRecordOrErr.get());
 102         RecordInitializer RI(E, OffsetPtr);
 103         if (auto Err = R->apply(RI))
 104           return std::move(Err);
 105         return std::move(R);
 106       }
 107     }
 108   }
 109   llvm_unreachable("Must always terminate with either an error or a record.");
 110 }
 111
 112 Expected<std::unique_ptr<Record>> FileBasedRecordProducer::produce() {
 113   // First, we set up our result record.
 114   std::unique_ptr<Record> R;
 115
 116   // Before we do any further reading, we should check whether we're at the end
 117   // of the current buffer we're been consuming. In FDR logs version >= 3, we
 118   // rely on the buffer extents record to determine how many bytes we should be
 119   // considering as valid records.
 120   if (Header.Version >= 3 && CurrentBufferBytes == 0) {
 121     // Find the next buffer extents record.
 122     auto BufferExtentsOrError = findNextBufferExtent();
 123     if (!BufferExtentsOrError)
 124       return joinErrors(
 125           BufferExtentsOrError.takeError(),
 126           createStringError(
 127               std::make_error_code(std::errc::executable_format_error),
 128               "Failed to find the next BufferExtents record."));
 129
 130     R = std::move(BufferExtentsOrError.get());
 131     assert(R != nullptr);
 132     assert(isa<BufferExtents>(R.get()));
 133     auto BE = dyn_cast<BufferExtents>(R.get());
 134     CurrentBufferBytes = BE->size();
 135     return std::move(R);
 136   }
 137
 138   //
 139   // At the top level, we read one byte to determine the type of the record to
 140   // create. This byte will comprise of the following bits:
 141   //
 142   //   - offset 0: A '1' indicates a metadata record, a '0' indicates a function
 143   //     record.
 144   //   - offsets 1-7: For metadata records, this will indicate the kind of
 145   //     metadata record should be loaded.
 146   //
 147   // We read first byte, then create the appropriate type of record to consume
 148   // the rest of the bytes.
 149   auto PreReadOffset = OffsetPtr;
 150   uint8_t FirstByte = E.getU8(&OffsetPtr);
 151   if (OffsetPtr == PreReadOffset)
 152     return createStringError(
 153         std::make_error_code(std::errc::executable_format_error),
 154         "Failed reading one byte from offset %d.", OffsetPtr);
 155
 156   // For metadata records, handle especially here.
 157   if (isMetadataIntroducer(FirstByte)) {
 158     auto LoadedType = FirstByte >> 1;
 159     auto MetadataRecordOrErr = metadataRecordType(Header, LoadedType);
 160     if (!MetadataRecordOrErr)
 161       return joinErrors(
 162           MetadataRecordOrErr.takeError(),
 163           createStringError(
 164               std::make_error_code(std::errc::executable_format_error),
 165               "Encountered an unsupported metadata record (%d) at offset %d.",
 166               LoadedType, PreReadOffset));
 167     R = std::move(MetadataRecordOrErr.get());
 168   } else {
 169     R = llvm::make_unique<FunctionRecord>();
 170   }
 171   RecordInitializer RI(E, OffsetPtr);
 172
 173   if (auto Err = R->apply(RI))
 174     return std::move(Err);
 175
 176   // If we encountered a BufferExtents record, we should record the remaining
 177   // bytes for the current buffer, to determine when we should start ignoring
 178   // potentially malformed data and looking for buffer extents records.
 179   if (auto BE = dyn_cast<BufferExtents>(R.get())) {
 180     CurrentBufferBytes = BE->size();
 181   } else if (Header.Version >= 3) {
 182     if (OffsetPtr - PreReadOffset > CurrentBufferBytes)
 183       return createStringError(
 184           std::make_error_code(std::errc::executable_format_error),
 185           "Buffer over-read at offset %d (over-read by %d bytes); Record Type "
 186           "= %s.",
 187           OffsetPtr, (OffsetPtr - PreReadOffset) - CurrentBufferBytes,
 188           Record::kindToString(R->getRecordType()).data());
 189
 190     CurrentBufferBytes -= OffsetPtr - PreReadOffset;
 191   }
 192   assert(R != nullptr);
 193   return std::move(R);
 194 }
 195
 196 } // namespace xray
 197 } // namespace llvm