Class that decodes a raw buffer for a single PSB block using the low level libipt library. More...

Public Member Functions
	PSBBlockDecoder (PtInsnDecoderUP &&decoder_up, const PSBBlock &psb_block, std::optional< lldb::addr_t > next_block_ip, DecodedThread &decoded_thread, TraceIntelPT &trace_intel_pt, std::optional< DecodedThread::TSC > tsc_upper_bound)

void	DecodePSBBlock ()

Static Public Member Functions
static Expected< PSBBlockDecoder >	Create (TraceIntelPT &trace_intel_pt, const PSBBlock &psb_block, ArrayRef< uint8_t > buffer, Process &process, std::optional< lldb::addr_t > next_block_ip, DecodedThread &decoded_thread, std::optional< DecodedThread::TSC > tsc_upper_bound)

Private Member Functions
bool	AppendInstructionAndDetectAnomalies (const pt_insn &insn)
	Append an instruction and return false if and only if a serious anomaly has been detected.

void	DecodeInstructionsAndEvents (int status)
	Decode all the instructions and events of the given PSB block.

Error	ProcessPTEventTSC (DecodedThread::TSC tsc)
	Process the TSC of a decoded PT event.

int	ProcessPTEvents (int status)
	Before querying instructions, we need to query the events associated with that instruction, e.g.

Private Attributes
PtInsnDecoderUP	m_decoder_up

PSBBlock	m_psb_block

std::optional< lldb::addr_t >	m_next_block_ip

DecodedThread &	m_decoded_thread

PSBBlockAnomalyDetector	m_anomaly_detector

std::optional< DecodedThread::TSC >	m_tsc_upper_bound

Detailed Description

Class that decodes a raw buffer for a single PSB block using the low level libipt library.

It assumes that kernel and user mode instructions are not mixed in the same PSB block.

Throughout this code, the status of the decoder will be used to identify events needed to be processed or errors in the decoder. The values can be

negative: actual errors
positive or zero: not an error, but a list of bits signaling the status of the decoder, e.g. whether there are events that need to be decoded or not.

Definition at line 319 of file LibiptDecoder.cpp.

Constructor & Destructor Documentation

◆ PSBBlockDecoder()

PSBBlockDecoder::PSBBlockDecoder	(	PtInsnDecoderUP &&	decoder_up,
		const PSBBlock &	psb_block,
		std::optional< lldb::addr_t >	next_block_ip,
		DecodedThread &	decoded_thread,
		TraceIntelPT &	trace_intel_pt,
		std::optional< DecodedThread::TSC >	tsc_upper_bound
	)

inline

Parameters

[in]	decoder	A decoder configured to start and end within the boundaries of the given `psb_block`.
[in]	psb_block	The PSB block to decode.
[in]	next_block_ip	The starting ip at the next PSB block of the same thread if available.
[in]	decoded_thread	A DecodedThread object where the decoded instructions will be appended to. It might have already some instructions.
[in]	tsc_upper_bound	Maximum allowed value of TSCs decoded from this PSB block. Any of this PSB's data occurring after this TSC will be excluded.

Definition at line 338 of file LibiptDecoder.cpp.

Member Function Documentation

◆ AppendInstructionAndDetectAnomalies()

bool PSBBlockDecoder::AppendInstructionAndDetectAnomalies ( const pt_insn & insn )

inlineprivate

Append an instruction and return false if and only if a serious anomaly has been detected.

Definition at line 405 of file LibiptDecoder.cpp.

References lldb_private::trace_intel_pt::DecodedThread::AppendCustomError(), lldb_private::trace_intel_pt::DecodedThread::AppendInstruction(), PSBBlockAnomalyDetector::DetectAnomaly(), m_anomaly_detector, m_decoded_thread, and lldb_private::toString().

Referenced by DecodeInstructionsAndEvents().

◆ Create()

static Expected< PSBBlockDecoder > PSBBlockDecoder::Create	(	TraceIntelPT &	trace_intel_pt,
		const PSBBlock &	psb_block,
		ArrayRef< uint8_t >	buffer,
		Process &	process,
		std::optional< lldb::addr_t >	next_block_ip,
		DecodedThread &	decoded_thread,
		std::optional< DecodedThread::TSC >	tsc_upper_bound
	)

inlinestatic

Parameters

[in]	trace_intel_pt	The main Trace object that own the PSB block.
[in]	decoder	A decoder configured to start and end within the boundaries of the given `psb_block`.
[in]	psb_block	The PSB block to decode.
[in]	buffer	The raw intel pt trace for this block.
[in]	process	The process to decode. It provides the memory image to use for decoding.
[in]	next_block_ip	The starting ip at the next PSB block of the same thread if available.
[in]	decoded_thread	A DecodedThread object where the decoded instructions will be appended to. It might have already some instructions.

Definition at line 371 of file LibiptDecoder.cpp.

References CreateInstructionDecoder().

◆ DecodeInstructionsAndEvents()

void PSBBlockDecoder::DecodeInstructionsAndEvents ( int status )

inlineprivate

Decode all the instructions and events of the given PSB block.

The decoding loop might stop abruptly if an infinite decoding loop is detected.

Definition at line 418 of file LibiptDecoder.cpp.

References lldb_private::trace_intel_pt::DecodedThread::AppendError(), AppendInstructionAndDetectAnomalies(), IsEndOfStream(), IsLibiptError(), m_decoded_thread, m_decoder_up, m_next_block_ip, and ProcessPTEvents().

Referenced by DecodePSBBlock().

◆ DecodePSBBlock()

void PSBBlockDecoder::DecodePSBBlock ( )

inline

Definition at line 385 of file LibiptDecoder.cpp.

References DecodeInstructionsAndEvents(), m_decoded_thread, m_decoder_up, m_psb_block, lldb_private::trace_intel_pt::DecodedThread::NotifySyncPoint(), lldb_private::trace_intel_pt::DecodedThread::NotifyTsc(), lldb_private::trace_intel_pt::PSBBlock::psb_offset, and lldb_private::trace_intel_pt::PSBBlock::tsc.

◆ ProcessPTEvents()

int PSBBlockDecoder::ProcessPTEvents ( int status )

inlineprivate

Before querying instructions, we need to query the events associated with that instruction, e.g.

timing and trace disablement events.

Parameters

[in] status The status gotten from the previous instruction decoding or PSB synchronization.

Returns: The pte_status after decoding events.

Definition at line 508 of file LibiptDecoder.cpp.

References lldb_private::trace_intel_pt::DecodedThread::AppendError(), lldb_private::trace_intel_pt::DecodedThread::AppendEvent(), lldb::eTraceEventDisabledHW, lldb::eTraceEventDisabledSW, HasEvents(), IsLibiptError(), m_decoded_thread, m_decoder_up, and ProcessPTEventTSC().

Referenced by DecodeInstructionsAndEvents().

◆ ProcessPTEventTSC()

Error PSBBlockDecoder::ProcessPTEventTSC ( DecodedThread::TSC tsc )

inlineprivate

Process the TSC of a decoded PT event.

Specifically, check if this TSC is below the TSC upper bound for this PSB. If the TSC exceeds the upper bound, return an error to abort decoding. Otherwise add the it to the underlying DecodedThread and decoding should continue as expected.

Parameters

[in] tsc The TSC of the a decoded event.

Definition at line 471 of file LibiptDecoder.cpp.

References lldb_private::trace_intel_pt::DecodedThread::AppendCustomError(), IsLibiptError(), m_decoded_thread, m_decoder_up, m_psb_block, m_tsc_upper_bound, lldb_private::trace_intel_pt::DecodedThread::NotifyTsc(), and lldb_private::trace_intel_pt::PSBBlock::size.

Referenced by ProcessPTEvents().