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

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//===- Trace.cpp - XRay Trace Loading implementation. ---------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// 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/BlockIndexer.h"
#include "llvm/XRay/BlockVerifier.h"
#include "llvm/XRay/FDRRecordConsumer.h"
#include "llvm/XRay/FDRRecordProducer.h"
#include "llvm/XRay/FDRRecords.h"
#include "llvm/XRay/FDRTraceExpander.h"
#include "llvm/XRay/FileHeaderReader.h"
#include "llvm/XRay/YAMLXRayRecord.h"
#include <memory>
#include <vector>
using namespace llvm;
using namespace llvm::xray;
using llvm::yaml::Input;
namespace {
using XRayRecordStorage =
std::aligned_storage<sizeof(XRayRecord), alignof(XRayRecord)>::type;
Error loadNaiveFormatLog(StringRef Data, bool IsLittleEndian,
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, IsLittleEndian, 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();
}
/// 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*
///
/// In Version 4, we make the following changes:
///
/// CustomEventRecord now includes the CPU data.
///
/// In Version 5, we make the following changes:
///
/// CustomEventRecord and TypedEventRecord now use TSC delta encoding similar to
/// what FunctionRecord instances use, and we no longer need to include the CPU
/// id in the CustomEventRecord.
///
Error loadFDRLog(StringRef Data, bool IsLittleEndian,
XRayFileHeader &FileHeader, std::vector<XRayRecord> &Records) {
if (Data.size() < 32)
return createStringError(std::make_error_code(std::errc::invalid_argument),
"Not enough bytes for an XRay FDR log.");
DataExtractor DE(Data, IsLittleEndian, 8);
uint32_t OffsetPtr = 0;
auto FileHeaderOrError = readBinaryFormatHeader(DE, OffsetPtr);
if (!FileHeaderOrError)
return FileHeaderOrError.takeError();
FileHeader = std::move(FileHeaderOrError.get());
// First we load the records into memory.
std::vector<std::unique_ptr<Record>> FDRRecords;
{
FileBasedRecordProducer P(FileHeader, DE, OffsetPtr);
LogBuilderConsumer C(FDRRecords);
while (DE.isValidOffsetForDataOfSize(OffsetPtr, 1)) {
auto R = P.produce();
if (!R)
return R.takeError();
if (auto E = C.consume(std::move(R.get())))
return E;
}
}
// Next we index the records into blocks.
BlockIndexer::Index Index;
{
BlockIndexer Indexer(Index);
for (auto &R : FDRRecords)
if (auto E = R->apply(Indexer))
return E;
if (auto E = Indexer.flush())
return E;
}
// Then we verify the consistency of the blocks.
{
for (auto &PTB : Index) {
auto &Blocks = PTB.second;
for (auto &B : Blocks) {
BlockVerifier Verifier;
for (auto *R : B.Records)
if (auto E = R->apply(Verifier))
return E;
if (auto E = Verifier.verify())
return E;
}
}
}
// This is now the meat of the algorithm. Here we sort the blocks according to
// the Walltime record in each of the blocks for the same thread. This allows
// us to more consistently recreate the execution trace in temporal order.
// After the sort, we then reconstitute `Trace` records using a stateful
// visitor associated with a single process+thread pair.
{
for (auto &PTB : Index) {
auto &Blocks = PTB.second;
llvm::sort(Blocks, [](const BlockIndexer::Block &L,
const BlockIndexer::Block &R) {
return (L.WallclockTime->seconds() < R.WallclockTime->seconds() &&
L.WallclockTime->nanos() < R.WallclockTime->nanos());
});
auto Adder = [&](const XRayRecord &R) { Records.push_back(R); };
TraceExpander Expander(Adder, FileHeader.Version);
for (auto &B : Blocks) {
for (auto *R : B.Records)
if (auto E = R->apply(Expander))
return E;
}
if (auto E = Expander.flush())
return E;
}
}
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, R.Data};
});
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());
// TODO: Lift the endianness and implementation selection here.
DataExtractor LittleEndianDE(Data, true, 8);
auto TraceOrError = loadTrace(LittleEndianDE, Sort);
if (!TraceOrError) {
DataExtractor BigEndianDE(Data, false, 8);
TraceOrError = loadTrace(BigEndianDE, Sort);
}
return TraceOrError;
}
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(), DE.isLittleEndian(), 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(), DE.isLittleEndian(),
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 <= 5) {
if (auto E = loadFDRLog(DE.getData(), DE.isLittleEndian(), 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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