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llvm-project/llvm/lib/XRay/Trace.cpp

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//===- Trace.cpp - XRay Trace Loading implementation. ---------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// XRay log reader implementation.
//
//===----------------------------------------------------------------------===//
#include "llvm/XRay/Trace.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/DataExtractor.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/XRay/FileHeaderReader.h"
#include "llvm/XRay/YAMLXRayRecord.h"
using namespace llvm;
using namespace llvm::xray;
using llvm::yaml::Input;
namespace {
using XRayRecordStorage =
std::aligned_storage<sizeof(XRayRecord), alignof(XRayRecord)>::type;
// This is the number of bytes in the "body" of a MetadataRecord in FDR Mode.
// This already excludes the first byte, which indicates the type of metadata
// record it is.
constexpr auto kFDRMetadataBodySize = 15;
Error loadNaiveFormatLog(StringRef Data, XRayFileHeader &FileHeader,
std::vector<XRayRecord> &Records) {
if (Data.size() < 32)
return make_error<StringError>(
"Not enough bytes for an XRay log.",
std::make_error_code(std::errc::invalid_argument));
if (Data.size() - 32 == 0 || Data.size() % 32 != 0)
return make_error<StringError>(
"Invalid-sized XRay data.",
std::make_error_code(std::errc::invalid_argument));
DataExtractor Reader(Data, true, 8);
uint32_t OffsetPtr = 0;
auto FileHeaderOrError = readBinaryFormatHeader(Reader, OffsetPtr);
if (!FileHeaderOrError)
return FileHeaderOrError.takeError();
FileHeader = std::move(FileHeaderOrError.get());
// Each record after the header will be 32 bytes, in the following format:
//
// (2) uint16 : record type
// (1) uint8 : cpu id
// (1) uint8 : type
// (4) sint32 : function id
// (8) uint64 : tsc
// (4) uint32 : thread id
// (4) uint32 : process id
// (8) - : padding
while (Reader.isValidOffset(OffsetPtr)) {
if (!Reader.isValidOffsetForDataOfSize(OffsetPtr, 32))
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Not enough bytes to read a full record at offset %d.", OffsetPtr);
auto PreReadOffset = OffsetPtr;
auto RecordType = Reader.getU16(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading record type at offset %d.", OffsetPtr);
switch (RecordType) {
case 0: { // Normal records.
Records.emplace_back();
auto &Record = Records.back();
Record.RecordType = RecordType;
PreReadOffset = OffsetPtr;
Record.CPU = Reader.getU8(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading CPU field at offset %d.", OffsetPtr);
PreReadOffset = OffsetPtr;
auto Type = Reader.getU8(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading record type field at offset %d.", OffsetPtr);
switch (Type) {
case 0:
Record.Type = RecordTypes::ENTER;
break;
case 1:
Record.Type = RecordTypes::EXIT;
break;
case 2:
Record.Type = RecordTypes::TAIL_EXIT;
break;
case 3:
Record.Type = RecordTypes::ENTER_ARG;
break;
default:
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Unknown record type '%d' at offset %d.", Type, OffsetPtr);
}
PreReadOffset = OffsetPtr;
Record.FuncId = Reader.getSigned(&OffsetPtr, sizeof(int32_t));
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading function id field at offset %d.", OffsetPtr);
PreReadOffset = OffsetPtr;
Record.TSC = Reader.getU64(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading TSC field at offset %d.", OffsetPtr);
PreReadOffset = OffsetPtr;
Record.TId = Reader.getU32(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading thread id field at offset %d.", OffsetPtr);
PreReadOffset = OffsetPtr;
Record.PId = Reader.getU32(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading process id at offset %d.", OffsetPtr);
break;
}
case 1: { // Arg payload record.
auto &Record = Records.back();
// We skip the next two bytes of the record, because we don't need the
// type and the CPU record for arg payloads.
OffsetPtr += 2;
PreReadOffset = OffsetPtr;
int32_t FuncId = Reader.getSigned(&OffsetPtr, sizeof(int32_t));
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading function id field at offset %d.", OffsetPtr);
PreReadOffset = OffsetPtr;
auto TId = Reader.getU32(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading thread id field at offset %d.", OffsetPtr);
PreReadOffset = OffsetPtr;
auto PId = Reader.getU32(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading process id field at offset %d.", OffsetPtr);
// Make a check for versions above 3 for the Pid field
if (Record.FuncId != FuncId || Record.TId != TId ||
(FileHeader.Version >= 3 ? Record.PId != PId : false))
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Corrupted log, found arg payload following non-matching "
"function+thread record. Record for function %d != %d at offset "
"%d",
Record.FuncId, FuncId, OffsetPtr);
PreReadOffset = OffsetPtr;
auto Arg = Reader.getU64(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading argument payload at offset %d.", OffsetPtr);
Record.CallArgs.push_back(Arg);
break;
}
default:
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Unknown record type '%d' at offset %d.", RecordType, OffsetPtr);
}
// Advance the offset pointer enough bytes to align to 32-byte records for
// basic mode logs.
OffsetPtr += 8;
}
return Error::success();
}
/// When reading from a Flight Data Recorder mode log, metadata records are
/// sparse compared to packed function records, so we must maintain state as we
/// read through the sequence of entries. This allows the reader to denormalize
/// the CPUId and Thread Id onto each Function Record and transform delta
/// encoded TSC values into absolute encodings on each record.
struct FDRState {
uint16_t CPUId;
uint16_t ThreadId;
int32_t ProcessId;
uint64_t BaseTSC;
/// Encode some of the state transitions for the FDR log reader as explicit
/// checks. These are expectations for the next Record in the stream.
enum class Token {
NEW_BUFFER_RECORD_OR_EOF,
WALLCLOCK_RECORD,
NEW_CPU_ID_RECORD,
FUNCTION_SEQUENCE,
SCAN_TO_END_OF_THREAD_BUF,
CUSTOM_EVENT_DATA,
CALL_ARGUMENT,
BUFFER_EXTENTS,
PID_RECORD,
};
Token Expects;
// Each threads buffer may have trailing garbage to scan over, so we track our
// progress.
uint64_t CurrentBufferSize;
uint64_t CurrentBufferConsumed;
};
const char *fdrStateToTwine(const FDRState::Token &state) {
switch (state) {
case FDRState::Token::NEW_BUFFER_RECORD_OR_EOF:
return "NEW_BUFFER_RECORD_OR_EOF";
case FDRState::Token::WALLCLOCK_RECORD:
return "WALLCLOCK_RECORD";
case FDRState::Token::NEW_CPU_ID_RECORD:
return "NEW_CPU_ID_RECORD";
case FDRState::Token::FUNCTION_SEQUENCE:
return "FUNCTION_SEQUENCE";
case FDRState::Token::SCAN_TO_END_OF_THREAD_BUF:
return "SCAN_TO_END_OF_THREAD_BUF";
case FDRState::Token::CUSTOM_EVENT_DATA:
return "CUSTOM_EVENT_DATA";
case FDRState::Token::CALL_ARGUMENT:
return "CALL_ARGUMENT";
case FDRState::Token::BUFFER_EXTENTS:
return "BUFFER_EXTENTS";
case FDRState::Token::PID_RECORD:
return "PID_RECORD";
}
return "UNKNOWN";
}
/// State transition when a NewBufferRecord is encountered.
Error processFDRNewBufferRecord(FDRState &State, DataExtractor &RecordExtractor,
uint32_t &OffsetPtr) {
if (State.Expects != FDRState::Token::NEW_BUFFER_RECORD_OR_EOF)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Malformed log: Read New Buffer record kind out of sequence; expected: "
"%s at offset %d.",
fdrStateToTwine(State.Expects), OffsetPtr);
auto PreReadOffset = OffsetPtr;
State.ThreadId = RecordExtractor.getU16(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading the thread id at offset %d.", OffsetPtr);
State.Expects = FDRState::Token::WALLCLOCK_RECORD;
// Advance the offset pointer by enough bytes representing the remaining
// padding in a metadata record.
OffsetPtr += kFDRMetadataBodySize - 2;
assert(OffsetPtr - PreReadOffset == kFDRMetadataBodySize);
return Error::success();
}
/// State transition when an EndOfBufferRecord is encountered.
Error processFDREndOfBufferRecord(FDRState &State, uint32_t &OffsetPtr) {
if (State.Expects == FDRState::Token::NEW_BUFFER_RECORD_OR_EOF)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Malformed log: Received EOB message without current buffer; expected: "
"%s at offset %d.",
fdrStateToTwine(State.Expects), OffsetPtr);
State.Expects = FDRState::Token::SCAN_TO_END_OF_THREAD_BUF;
// Advance the offset pointer by enough bytes representing the remaining
// padding in a metadata record.
OffsetPtr += kFDRMetadataBodySize;
return Error::success();
}
/// State transition when a NewCPUIdRecord is encountered.
Error processFDRNewCPUIdRecord(FDRState &State, DataExtractor &RecordExtractor,
uint32_t &OffsetPtr) {
if (State.Expects != FDRState::Token::FUNCTION_SEQUENCE &&
State.Expects != FDRState::Token::NEW_CPU_ID_RECORD)
return make_error<StringError>(
Twine("Malformed log. Read NewCPUId record kind out of sequence; "
"expected: ") +
fdrStateToTwine(State.Expects),
std::make_error_code(std::errc::executable_format_error));
auto BeginOffset = OffsetPtr;
auto PreReadOffset = OffsetPtr;
State.CPUId = RecordExtractor.getU16(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading the CPU field at offset %d.", OffsetPtr);
PreReadOffset = OffsetPtr;
State.BaseTSC = RecordExtractor.getU64(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading the base TSC field at offset %d.", OffsetPtr);
State.Expects = FDRState::Token::FUNCTION_SEQUENCE;
// Advance the offset pointer by a few bytes, to account for the padding in
// CPU ID metadata records that we've already advanced through.
OffsetPtr += kFDRMetadataBodySize - (OffsetPtr - BeginOffset);
assert(OffsetPtr - BeginOffset == kFDRMetadataBodySize);
return Error::success();
}
/// State transition when a TSCWrapRecord (overflow detection) is encountered.
Error processFDRTSCWrapRecord(FDRState &State, DataExtractor &RecordExtractor,
uint32_t &OffsetPtr) {
if (State.Expects != FDRState::Token::FUNCTION_SEQUENCE)
return make_error<StringError>(
Twine("Malformed log. Read TSCWrap record kind out of sequence; "
"expecting: ") +
fdrStateToTwine(State.Expects),
std::make_error_code(std::errc::executable_format_error));
auto PreReadOffset = OffsetPtr;
State.BaseTSC = RecordExtractor.getU64(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading the base TSC field at offset %d.", OffsetPtr);
// Advance the offset pointer by a few more bytes, accounting for the padding
// in the metadata record after reading the base TSC.
OffsetPtr += kFDRMetadataBodySize - 8;
assert(OffsetPtr - PreReadOffset == kFDRMetadataBodySize);
return Error::success();
}
/// State transition when a WallTimeMarkerRecord is encountered.
Error processFDRWallTimeRecord(FDRState &State, DataExtractor &RecordExtractor,
uint32_t &OffsetPtr) {
if (State.Expects != FDRState::Token::WALLCLOCK_RECORD)
return make_error<StringError>(
Twine("Malformed log. Read Wallclock record kind out of sequence; "
"expecting: ") +
fdrStateToTwine(State.Expects),
std::make_error_code(std::errc::executable_format_error));
// Read in the data from the walltime record.
auto PreReadOffset = OffsetPtr;
auto WallTime = RecordExtractor.getU64(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading the walltime record at offset %d.", OffsetPtr);
// TODO: Someday, reconcile the TSC ticks to wall clock time for presentation
// purposes. For now, we're ignoring these records.
(void)WallTime;
State.Expects = FDRState::Token::NEW_CPU_ID_RECORD;
// Advance the offset pointer by a few more bytes, accounting for the padding
// in the metadata record after reading in the walltime data.
OffsetPtr += kFDRMetadataBodySize - 8;
assert(OffsetPtr - PreReadOffset == kFDRMetadataBodySize);
return Error::success();
}
/// State transition when a PidRecord is encountered.
Error processFDRPidRecord(FDRState &State, DataExtractor &RecordExtractor,
uint32_t &OffsetPtr) {
if (State.Expects != FDRState::Token::PID_RECORD)
return make_error<StringError>(
Twine("Malformed log. Read Pid record kind out of sequence; "
"expected: ") +
fdrStateToTwine(State.Expects),
std::make_error_code(std::errc::executable_format_error));
auto PreReadOffset = OffsetPtr;
State.ProcessId = RecordExtractor.getU32(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading the process ID at offset %d.", OffsetPtr);
State.Expects = FDRState::Token::NEW_CPU_ID_RECORD;
// Advance the offset pointer by a few more bytes, accounting for the padding
// in the metadata record after reading in the PID.
OffsetPtr += kFDRMetadataBodySize - 4;
assert(OffsetPtr - PreReadOffset == kFDRMetadataBodySize);
return Error::success();
}
/// State transition when a CustomEventMarker is encountered.
Error processCustomEventMarker(FDRState &State, DataExtractor &RecordExtractor,
uint32_t &OffsetPtr) {
// We can encounter a CustomEventMarker anywhere in the log, so we can handle
// it regardless of the expectation. However, we do set the expectation to
// read a set number of fixed bytes, as described in the metadata.
auto BeginOffset = OffsetPtr;
auto PreReadOffset = OffsetPtr;
uint32_t DataSize = RecordExtractor.getU32(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading a custom event marker at offset %d.", OffsetPtr);
PreReadOffset = OffsetPtr;
uint64_t TSC = RecordExtractor.getU64(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading the TSC at offset %d.", OffsetPtr);
// FIXME: Actually represent the record through the API. For now we only
// skip through the data.
(void)TSC;
// Advance the offset ptr by the size of the data associated with the custom
// event, as well as the padding associated with the remainder of the metadata
// record.
OffsetPtr += (kFDRMetadataBodySize - (OffsetPtr - BeginOffset)) + DataSize;
if (!RecordExtractor.isValidOffset(OffsetPtr))
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Reading custom event data moves past addressable trace data (starting "
"at offset %d, advancing to offset %d).",
BeginOffset, OffsetPtr);
return Error::success();
}
/// State transition when an BufferExtents record is encountered.
Error processBufferExtents(FDRState &State, DataExtractor &RecordExtractor,
uint32_t &OffsetPtr) {
if (State.Expects != FDRState::Token::BUFFER_EXTENTS)
return make_error<StringError>(
Twine("Malformed log. Buffer Extents unexpected; expected: ") +
fdrStateToTwine(State.Expects),
std::make_error_code(std::errc::executable_format_error));
auto PreReadOffset = OffsetPtr;
State.CurrentBufferSize = RecordExtractor.getU64(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed to read current buffer size at offset %d.", OffsetPtr);
State.Expects = FDRState::Token::NEW_BUFFER_RECORD_OR_EOF;
// Advance the offset pointer by enough bytes accounting for the padding in a
// metadata record, after we read in the buffer extents.
OffsetPtr += kFDRMetadataBodySize - 8;
return Error::success();
}
/// State transition when a CallArgumentRecord is encountered.
Error processFDRCallArgumentRecord(FDRState &State,
DataExtractor &RecordExtractor,
std::vector<XRayRecord> &Records,
uint32_t &OffsetPtr) {
auto &Enter = Records.back();
if (Enter.Type != RecordTypes::ENTER && Enter.Type != RecordTypes::ENTER_ARG)
return make_error<StringError>(
"CallArgument needs to be right after a function entry",
std::make_error_code(std::errc::executable_format_error));
auto PreReadOffset = OffsetPtr;
auto Arg = RecordExtractor.getU64(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed to read argument record at offset %d.", OffsetPtr);
Enter.Type = RecordTypes::ENTER_ARG;
Enter.CallArgs.emplace_back(Arg);
// Advance the offset pointer by enough bytes accounting for the padding in a
// metadata record, after reading the payload.
OffsetPtr += kFDRMetadataBodySize - 8;
return Error::success();
}
/// Advances the state machine for reading the FDR record type by reading one
/// Metadata Record and updating the State appropriately based on the kind of
/// record encountered. The RecordKind is encoded in the first byte of the
/// Record, which the caller should pass in because they have already read it
/// to determine that this is a metadata record as opposed to a function record.
///
/// Beginning with Version 2 of the FDR log, we do not depend on the size of the
/// buffer, but rather use the extents to determine how far to read in the log
/// for this particular buffer.
///
/// In Version 3, FDR log now includes a pid metadata record after
/// WallTimeMarker
Error processFDRMetadataRecord(FDRState &State, DataExtractor &RecordExtractor,
uint32_t &OffsetPtr,
std::vector<XRayRecord> &Records,
uint16_t Version, uint8_t FirstByte) {
// The remaining 7 bits of the first byte are the RecordKind enum for each
// Metadata Record.
switch (FirstByte >> 1) {
case 0: // NewBuffer
if (auto E = processFDRNewBufferRecord(State, RecordExtractor, OffsetPtr))
return E;
break;
case 1: // EndOfBuffer
if (Version >= 2)
return make_error<StringError>(
"Since Version 2 of FDR logging, we no longer support EOB records.",
std::make_error_code(std::errc::executable_format_error));
if (auto E = processFDREndOfBufferRecord(State, OffsetPtr))
return E;
break;
case 2: // NewCPUId
if (auto E = processFDRNewCPUIdRecord(State, RecordExtractor, OffsetPtr))
return E;
break;
case 3: // TSCWrap
if (auto E = processFDRTSCWrapRecord(State, RecordExtractor, OffsetPtr))
return E;
break;
case 4: // WallTimeMarker
if (auto E = processFDRWallTimeRecord(State, RecordExtractor, OffsetPtr))
return E;
// In Version 3 and and above, a PidRecord is expected after WallTimeRecord
if (Version >= 3)
State.Expects = FDRState::Token::PID_RECORD;
break;
case 5: // CustomEventMarker
if (auto E = processCustomEventMarker(State, RecordExtractor, OffsetPtr))
return E;
break;
case 6: // CallArgument
if (auto E = processFDRCallArgumentRecord(State, RecordExtractor, Records,
OffsetPtr))
return E;
break;
case 7: // BufferExtents
if (auto E = processBufferExtents(State, RecordExtractor, OffsetPtr))
return E;
break;
case 9: // Pid
if (auto E = processFDRPidRecord(State, RecordExtractor, OffsetPtr))
return E;
break;
default:
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Illegal metadata record type: '%d' at offset %d.", FirstByte >> 1,
OffsetPtr);
}
return Error::success();
}
/// Reads a function record from an FDR format log, appending a new XRayRecord
/// to the vector being populated and updating the State with a new value
/// reference value to interpret TSC deltas.
///
/// The XRayRecord constructed includes information from the function record
/// processed here as well as Thread ID and CPU ID formerly extracted into
/// State.
Error processFDRFunctionRecord(FDRState &State, DataExtractor &RecordExtractor,
uint32_t &OffsetPtr, uint8_t FirstByte,
std::vector<XRayRecord> &Records) {
switch (State.Expects) {
case FDRState::Token::NEW_BUFFER_RECORD_OR_EOF:
return make_error<StringError>(
"Malformed log. Received Function Record before new buffer setup.",
std::make_error_code(std::errc::executable_format_error));
case FDRState::Token::WALLCLOCK_RECORD:
return make_error<StringError>(
"Malformed log. Received Function Record when expecting wallclock.",
std::make_error_code(std::errc::executable_format_error));
case FDRState::Token::PID_RECORD:
return make_error<StringError>(
"Malformed log. Received Function Record when expecting pid.",
std::make_error_code(std::errc::executable_format_error));
case FDRState::Token::NEW_CPU_ID_RECORD:
return make_error<StringError>(
"Malformed log. Received Function Record before first CPU record.",
std::make_error_code(std::errc::executable_format_error));
default:
Records.emplace_back();
auto &Record = Records.back();
Record.RecordType = 0; // Record is type NORMAL.
// Strip off record type bit and use the next three bits.
auto T = (FirstByte >> 1) & 0x07;
switch (T) {
case static_cast<decltype(T)>(RecordTypes::ENTER):
Record.Type = RecordTypes::ENTER;
break;
case static_cast<decltype(T)>(RecordTypes::EXIT):
Record.Type = RecordTypes::EXIT;
break;
case static_cast<decltype(T)>(RecordTypes::TAIL_EXIT):
Record.Type = RecordTypes::TAIL_EXIT;
break;
case static_cast<decltype(T)>(RecordTypes::ENTER_ARG):
Record.Type = RecordTypes::ENTER_ARG;
State.Expects = FDRState::Token::CALL_ARGUMENT;
break;
default:
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Illegal function record type '%d' at offset %d.", T, OffsetPtr);
}
Record.CPU = State.CPUId;
Record.TId = State.ThreadId;
Record.PId = State.ProcessId;
// Back up one byte to re-read the first byte, which is important for
// computing the function id for a record.
--OffsetPtr;
// Despite function Id being a signed int on XRayRecord,
// when it is written to an FDR format, the top bits are truncated,
// so it is effectively an unsigned value. When we shift off the
// top four bits, we want the shift to be logical, so we read as
// uint32_t.
auto PreReadOffset = OffsetPtr;
uint32_t FuncIdBitField = RecordExtractor.getU32(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading truncated function id field at offset %d.",
OffsetPtr);
Record.FuncId = FuncIdBitField >> 4;
// FunctionRecords have a 32 bit delta from the previous absolute TSC
// or TSC delta. If this would overflow, we should read a TSCWrap record
// with an absolute TSC reading.
PreReadOffset = OffsetPtr;
uint64_t NewTSC = State.BaseTSC + RecordExtractor.getU32(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading TSC delta at offset %d.", OffsetPtr);
State.BaseTSC = NewTSC;
Record.TSC = NewTSC;
}
return Error::success();
}
/// Reads a log in FDR mode for version 1 of this binary format. FDR mode is
/// defined as part of the compiler-rt project in xray_fdr_logging.h, and such
/// a log consists of the familiar 32 bit XRayHeader, followed by sequences of
/// of interspersed 16 byte Metadata Records and 8 byte Function Records.
///
/// The following is an attempt to document the grammar of the format, which is
/// parsed by this function for little-endian machines. Since the format makes
/// use of BitFields, when we support big-endian architectures, we will need to
/// adjust not only the endianness parameter to llvm's RecordExtractor, but also
/// the bit twiddling logic, which is consistent with the little-endian
/// convention that BitFields within a struct will first be packed into the
/// least significant bits the address they belong to.
///
/// We expect a format complying with the grammar in the following pseudo-EBNF
/// in Version 1 of the FDR log.
///
/// FDRLog: XRayFileHeader ThreadBuffer*
/// XRayFileHeader: 32 bytes to identify the log as FDR with machine metadata.
/// Includes BufferSize
/// ThreadBuffer: NewBuffer WallClockTime NewCPUId FunctionSequence EOB
/// BufSize: 8 byte unsigned integer indicating how large the buffer is.
/// NewBuffer: 16 byte metadata record with Thread Id.
/// WallClockTime: 16 byte metadata record with human readable time.
/// Pid: 16 byte metadata record with Pid
/// NewCPUId: 16 byte metadata record with CPUId and a 64 bit TSC reading.
/// EOB: 16 byte record in a thread buffer plus mem garbage to fill BufSize.
/// FunctionSequence: NewCPUId | TSCWrap | FunctionRecord
/// TSCWrap: 16 byte metadata record with a full 64 bit TSC reading.
/// FunctionRecord: 8 byte record with FunctionId, entry/exit, and TSC delta.
///
/// In Version 2, we make the following changes:
///
/// ThreadBuffer: BufferExtents NewBuffer WallClockTime NewCPUId
/// FunctionSequence
/// BufferExtents: 16 byte metdata record describing how many usable bytes are
/// in the buffer. This is measured from the start of the buffer
/// and must always be at least 48 (bytes).
///
/// In Version 3, we make the following changes:
///
/// ThreadBuffer: BufferExtents NewBuffer WallClockTime Pid NewCPUId
/// FunctionSequence
/// EOB: *deprecated*
Error loadFDRLog(StringRef Data, XRayFileHeader &FileHeader,
std::vector<XRayRecord> &Records) {
if (Data.size() < 32)
return make_error<StringError>(
"Not enough bytes for an XRay log.",
std::make_error_code(std::errc::invalid_argument));
DataExtractor Reader(Data, true, 8);
uint32_t OffsetPtr = 0;
auto FileHeaderOrError = readBinaryFormatHeader(Reader, OffsetPtr);
if (!FileHeaderOrError)
return FileHeaderOrError.takeError();
FileHeader = std::move(FileHeaderOrError.get());
uint64_t BufferSize = 0;
{
StringRef ExtraDataRef(FileHeader.FreeFormData, 16);
DataExtractor ExtraDataExtractor(ExtraDataRef, true, 8);
uint32_t ExtraDataOffset = 0;
BufferSize = ExtraDataExtractor.getU64(&ExtraDataOffset);
}
FDRState::Token InitialExpectation;
switch (FileHeader.Version) {
case 1:
InitialExpectation = FDRState::Token::NEW_BUFFER_RECORD_OR_EOF;
break;
case 2:
case 3:
InitialExpectation = FDRState::Token::BUFFER_EXTENTS;
break;
default:
return make_error<StringError>(
Twine("Unsupported version '") + Twine(FileHeader.Version) + "'",
std::make_error_code(std::errc::executable_format_error));
}
FDRState State{0, 0, 0, 0, InitialExpectation, BufferSize, 0};
// RecordSize will tell the loop how far to seek ahead based on the record
// type that we have just read.
while (Reader.isValidOffset(OffsetPtr)) {
auto BeginOffset = OffsetPtr;
if (State.Expects == FDRState::Token::SCAN_TO_END_OF_THREAD_BUF) {
OffsetPtr += State.CurrentBufferSize - State.CurrentBufferConsumed;
State.CurrentBufferConsumed = 0;
State.Expects = FDRState::Token::NEW_BUFFER_RECORD_OR_EOF;
continue;
}
auto PreReadOffset = OffsetPtr;
uint8_t BitField = Reader.getU8(&OffsetPtr);
if (OffsetPtr == PreReadOffset)
return createStringError(
std::make_error_code(std::errc::executable_format_error),
"Failed reading first byte of record at offset %d.", OffsetPtr);
bool isMetadataRecord = BitField & 0x01uL;
bool isBufferExtents =
(BitField >> 1) == 7; // BufferExtents record kind == 7
if (isMetadataRecord) {
if (auto E = processFDRMetadataRecord(State, Reader, OffsetPtr, Records,
FileHeader.Version, BitField))
return E;
} else { // Process Function Record
if (auto E = processFDRFunctionRecord(State, Reader, OffsetPtr, BitField,
Records))
return E;
}
// The BufferExtents record is technically not part of the buffer, so we
// don't count the size of that record against the buffer's actual size.
if (!isBufferExtents)
State.CurrentBufferConsumed += OffsetPtr - BeginOffset;
assert(State.CurrentBufferConsumed <= State.CurrentBufferSize);
if ((FileHeader.Version == 2 || FileHeader.Version == 3) &&
State.CurrentBufferSize == State.CurrentBufferConsumed) {
// In Version 2 of the log, we don't need to scan to the end of the thread
// buffer if we've already consumed all the bytes we need to.
State.Expects = FDRState::Token::BUFFER_EXTENTS;
State.CurrentBufferSize = BufferSize;
State.CurrentBufferConsumed = 0;
}
}
// Having iterated over everything we've been given, we've either consumed
// everything and ended up in the end state, or were told to skip the rest.
bool Finished = State.Expects == FDRState::Token::SCAN_TO_END_OF_THREAD_BUF &&
State.CurrentBufferSize == State.CurrentBufferConsumed;
if ((State.Expects != FDRState::Token::NEW_BUFFER_RECORD_OR_EOF &&
State.Expects != FDRState::Token::BUFFER_EXTENTS) &&
!Finished)
return make_error<StringError>(
Twine("Encountered EOF with unexpected state expectation ") +
fdrStateToTwine(State.Expects) +
". Remaining expected bytes in thread buffer total " +
Twine(State.CurrentBufferSize - State.CurrentBufferConsumed),
std::make_error_code(std::errc::executable_format_error));
return Error::success();
}
Error loadYAMLLog(StringRef Data, XRayFileHeader &FileHeader,
std::vector<XRayRecord> &Records) {
YAMLXRayTrace Trace;
Input In(Data);
In >> Trace;
if (In.error())
return make_error<StringError>("Failed loading YAML Data.", In.error());
FileHeader.Version = Trace.Header.Version;
FileHeader.Type = Trace.Header.Type;
FileHeader.ConstantTSC = Trace.Header.ConstantTSC;
FileHeader.NonstopTSC = Trace.Header.NonstopTSC;
FileHeader.CycleFrequency = Trace.Header.CycleFrequency;
if (FileHeader.Version != 1)
return make_error<StringError>(
Twine("Unsupported XRay file version: ") + Twine(FileHeader.Version),
std::make_error_code(std::errc::invalid_argument));
Records.clear();
std::transform(Trace.Records.begin(), Trace.Records.end(),
std::back_inserter(Records), [&](const YAMLXRayRecord &R) {
return XRayRecord{R.RecordType, R.CPU, R.Type, R.FuncId,
R.TSC, R.TId, R.PId, R.CallArgs};
});
return Error::success();
}
} // namespace
Expected<Trace> llvm::xray::loadTraceFile(StringRef Filename, bool Sort) {
int Fd;
if (auto EC = sys::fs::openFileForRead(Filename, Fd)) {
return make_error<StringError>(
Twine("Cannot read log from '") + Filename + "'", EC);
}
uint64_t FileSize;
if (auto EC = sys::fs::file_size(Filename, FileSize)) {
return make_error<StringError>(
Twine("Cannot read log from '") + Filename + "'", EC);
}
if (FileSize < 4) {
return make_error<StringError>(
Twine("File '") + Filename + "' too small for XRay.",
std::make_error_code(std::errc::executable_format_error));
}
// Map the opened file into memory and use a StringRef to access it later.
std::error_code EC;
sys::fs::mapped_file_region MappedFile(
Fd, sys::fs::mapped_file_region::mapmode::readonly, FileSize, 0, EC);
if (EC) {
return make_error<StringError>(
Twine("Cannot read log from '") + Filename + "'", EC);
}
auto Data = StringRef(MappedFile.data(), MappedFile.size());
DataExtractor DE(Data, true, 8);
return loadTrace(DE, Sort);
}
Expected<Trace> llvm::xray::loadTrace(const DataExtractor &DE, bool Sort) {
// Attempt to detect the file type using file magic. We have a slight bias
// towards the binary format, and we do this by making sure that the first 4
// bytes of the binary file is some combination of the following byte
// patterns: (observe the code loading them assumes they're little endian)
//
// 0x01 0x00 0x00 0x00 - version 1, "naive" format
// 0x01 0x00 0x01 0x00 - version 1, "flight data recorder" format
// 0x02 0x00 0x01 0x00 - version 2, "flight data recorder" format
//
// YAML files don't typically have those first four bytes as valid text so we
// try loading assuming YAML if we don't find these bytes.
//
// Only if we can't load either the binary or the YAML format will we yield an
// error.
DataExtractor HeaderExtractor(DE.getData(), true, 8);
uint32_t OffsetPtr = 0;
uint16_t Version = HeaderExtractor.getU16(&OffsetPtr);
uint16_t Type = HeaderExtractor.getU16(&OffsetPtr);
enum BinaryFormatType { NAIVE_FORMAT = 0, FLIGHT_DATA_RECORDER_FORMAT = 1 };
Trace T;
switch (Type) {
case NAIVE_FORMAT:
if (Version == 1 || Version == 2 || Version == 3) {
if (auto E = loadNaiveFormatLog(DE.getData(), T.FileHeader, T.Records))
return std::move(E);
} else {
return make_error<StringError>(
Twine("Unsupported version for Basic/Naive Mode logging: ") +
Twine(Version),
std::make_error_code(std::errc::executable_format_error));
}
break;
case FLIGHT_DATA_RECORDER_FORMAT:
if (Version == 1 || Version == 2 || Version == 3) {
if (auto E = loadFDRLog(DE.getData(), T.FileHeader, T.Records))
return std::move(E);
} else {
return make_error<StringError>(
Twine("Unsupported version for FDR Mode logging: ") + Twine(Version),
std::make_error_code(std::errc::executable_format_error));
}
break;
default:
if (auto E = loadYAMLLog(DE.getData(), T.FileHeader, T.Records))
return std::move(E);
}
if (Sort)
std::stable_sort(T.Records.begin(), T.Records.end(),
[&](const XRayRecord &L, const XRayRecord &R) {
return L.TSC < R.TSC;
});
return std::move(T);
}
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