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opencsd: etm4: reject TRACE_INFO with speculation depth above MAXSPEC #93

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opencsd: etm4: reject TRACE_INFO with speculation depth above MAXSPEC #93

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2 changes: 1 addition & 1 deletion decoder/include/opencsd/etmv4/trc_pkt_decode_etmv4i.h
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Original file line number Diff line number Diff line change
Expand Up @@ -78,7 +78,7 @@ class TrcPktDecodeEtmV4I : public TrcPktDecodeBase<EtmV4ITrcPacket, EtmV4Config>
ocsd_err_t mispredictAtom(); // mispredict an atom
ocsd_err_t discardElements(); // discard elements and flush

bool doTraceInfoPacket();
ocsd_err_t doTraceInfoPacket(); // OCSD_ERR_BAD_DECODE_PKT: corrupt packet, caller re-syncs
void updateContext(TrcStackElemCtxt* pCtxtElem, OcsdTraceElement& elem);

// process atom will create instruction trace, or no memory access trace output elements.
Expand Down
40 changes: 31 additions & 9 deletions decoder/source/etmv4/trc_pkt_decode_etmv4i.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -104,11 +104,20 @@ ocsd_datapath_resp_t TrcPktDecodeEtmV4I::processPacket()
if(m_curr_packet_in->getType() == ETM4_PKT_I_TRACE_INFO)
{
// do the first trace info packet after sync.
if (!doTraceInfoPacket())
ocsd_err_t tierr = doTraceInfoPacket();
if (tierr == OCSD_ERR_BAD_DECODE_PKT)
{
// corrupt TRACE_INFO (speculation depth above TRCIDR8.MAXSPEC):
// drop it and wait for the next sync rather than fail the decode.
m_curr_state = WAIT_SYNC;
}
else if (tierr != OCSD_OK)
resp = OCSD_RESP_FATAL_SYS_ERR;

m_curr_state = DECODE_PKTS;
m_return_stack.flush();
else
{
m_curr_state = DECODE_PKTS;
m_return_stack.flush();
}
}
/* ETE spec allows early event packets. */
else if ((m_config->MajVersion() >= 0x5) &&
Expand Down Expand Up @@ -693,19 +702,32 @@ ocsd_err_t TrcPktDecodeEtmV4I::decodePacket()
}

// On first trace info we see - set up the trace parameters it contains.
bool TrcPktDecodeEtmV4I::doTraceInfoPacket()
ocsd_err_t TrcPktDecodeEtmV4I::doTraceInfoPacket()
{
m_trace_info = m_curr_packet_in->getTraceInfo();
m_cc_threshold = m_curr_packet_in->getCCThreshold();
m_curr_spec_depth = m_curr_packet_in->getCurrSpecDepth();

// A TRACE_INFO cannot report more outstanding speculative P0 elements than the
// implementation supports (TRCIDR8.MAXSPEC, 0 on cores without speculation).
// A larger value is a corrupt or mis-synchronised packet: honouring it below
// allocates one placeholder element per unit of depth with no upper bound (a
// garbage depth of 44M cost 1.3 GB of heap), so reject the packet instead.
if (m_curr_spec_depth > m_max_spec_depth)
{
LogError(ocsdError(OCSD_ERR_SEV_ERROR, OCSD_ERR_BAD_DECODE_PKT, m_index_curr_pkt, m_CSID,
"TRACE_INFO speculation depth exceeds TRCIDR8.MAXSPEC - packet rejected, waiting for sync."));
m_curr_spec_depth = 0;
return OCSD_ERR_BAD_DECODE_PKT;
}

// create m_curr_spec_depth unseen elements at the start of the P0 stack
if (m_P0_stack.createUnseenUncommitedP0Elem(m_curr_spec_depth, m_curr_packet_in->getType(), m_index_curr_pkt) != m_curr_spec_depth)
return false;
return OCSD_ERR_MEM;

// mark mark the TINFO position.
if (m_P0_stack.createParamElemNoParam(P0_TINFO, false, m_curr_packet_in->getType(), m_index_curr_pkt) == 0)
return false;
return OCSD_ERR_MEM;

/* put a trans marker in stack if started in trans state */
if (m_trace_info.bits.in_trans_state)
Expand All @@ -715,7 +737,7 @@ bool TrcPktDecodeEtmV4I::doTraceInfoPacket()
#ifdef DATA_TRACE_SUPPORTED
m_p0_key = m_curr_packet_in->getP0Key();
#endif
return true;
return OCSD_OK;
}

/* Element resolution
Expand Down