/*
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* Copyright (c) 2016, Google Inc.
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* All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#include <cstring>
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#include <iomanip>
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#include <memory>
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#include <sstream>
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#include <unordered_map>
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#include <vector>
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#include "int_compat.h"
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#include "intervalmap.h"
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#include "path_matching.h"
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#include "perf_data_handler.h"
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#include "string_compat.h"
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#include "quipper/perf_reader.h"
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using quipper::PerfDataProto;
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using quipper::PerfDataProto_MMapEvent;
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using quipper::PerfDataProto_CommEvent;
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namespace perftools {
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namespace {
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// Normalizer processes a PerfDataProto and maintains tables to the
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// current metadata for each process. It drives callbacks to
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// PerfDataHandler with samples in a fully normalized form.
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class Normalizer {
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public:
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Normalizer(const PerfDataProto& perf_proto, PerfDataHandler* handler)
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: perf_proto_(perf_proto), handler_(handler) {
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for (const auto& build_id : perf_proto_.build_ids()) {
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const string& bytes = build_id.build_id_hash();
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std::stringstream hex;
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for (size_t i = 0; i < bytes.size(); ++i) {
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// The char must be turned into an int to be used by stringstream;
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// however, if the byte's value -8 it should be turned to 0x00f8 as an
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// int, not 0xfff8. This cast solves this problem.
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const auto& byte = static_cast<unsigned char>(bytes[i]);
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hex << std::hex << std::setfill('0') << std::setw(2)
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<< static_cast<int>(byte);
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}
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if (build_id.filename() != "") {
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filename_to_build_id_[build_id.filename()] = hex.str();
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} else {
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std::stringstream filename;
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filename << std::hex << build_id.filename_md5_prefix();
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filename_to_build_id_[filename.str().c_str()] = hex.str();
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}
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}
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uint64 current_event_index = 0;
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for (const auto& attr : perf_proto_.file_attrs()) {
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for (uint64 id : attr.ids()) {
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id_to_event_index_[id] = current_event_index;
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}
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current_event_index++;
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}
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}
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Normalizer(const Normalizer&) = delete;
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Normalizer& operator=(const Normalizer&) = delete;
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~Normalizer() {}
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// Convert to a protobuf using quipper and then aggregate the results.
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void Normalize();
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private:
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// Using a 32-bit type for the PID values as the max PID value on 64-bit
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// systems is 2^22, see http://man7.org/linux/man-pages/man5/proc.5.html.
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typedef std::unordered_map<uint32, PerfDataHandler::Mapping*> PidToMMapMap;
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typedef std::unordered_map<uint32, const PerfDataProto_CommEvent*>
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PidToCommMap;
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typedef IntervalMap<const PerfDataHandler::Mapping*> MMapIntervalMap;
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// Copy the parent's mmaps/comm if they exist. Otherwise, items
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// will be lazily populated.
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void UpdateMapsWithMMapEvent(const quipper::PerfDataProto_MMapEvent* mmap);
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void UpdateMapsWithForkEvent(const quipper::PerfDataProto_ForkEvent& fork);
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void LogStats();
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// Normalize the sample_event in event_proto and call handler_->Sample
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void InvokeHandleSample(const quipper::PerfDataProto::PerfEvent& perf_event);
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// Find the MMAP event which has ip in its address range from pid. If no
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// mapping is found, returns nullptr.
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const PerfDataHandler::Mapping* TryLookupInPid(uint32 pid, uint64 ip) const;
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// Find the mapping for a given ip given a pid context (in user or kernel
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// mappings); returns nullptr if none can be found.
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const PerfDataHandler::Mapping* GetMappingFromPidAndIP(uint32 pid,
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uint64 ip) const;
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// Find the main MMAP event for this pid. If no mapping is found,
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// nullptr is returned.
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const PerfDataHandler::Mapping* GetMainMMapFromPid(uint32 pid) const;
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// For profiles with a single event, perf doesn't bother sending the
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// id. So, if there is only one event, the event index must be 0.
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// Returns the event index corresponding to the id for this sample, or
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// -1 for an error.
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int64 GetEventIndexForSample(
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const quipper::PerfDataProto_SampleEvent& sample) const;
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const quipper::PerfDataProto& perf_proto_;
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PerfDataHandler* handler_; // unowned.
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// Mapping we have allocated.
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std::vector<std::unique_ptr<PerfDataHandler::Mapping>> owned_mappings_;
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std::vector<std::unique_ptr<quipper::PerfDataProto_MMapEvent>>
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owned_quipper_mappings_;
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// The event for a given sample is determined by the id.
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// Map each id to an index in the event_profiles_ vector.
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std::unordered_map<uint64, uint64> id_to_event_index_;
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// pid_to_comm_event maps a pid to the corresponding comm event.
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PidToCommMap pid_to_comm_event_;
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// pid_to_mmaps maps a pid to all mmap events that correspond to that pid.
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std::unordered_map<uint32, std::unique_ptr<MMapIntervalMap>> pid_to_mmaps_;
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// pid_to_executable_mmap maps a pid to mmap that most likely contains the
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// filename of the main executable for that pid.
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PidToMMapMap pid_to_executable_mmap_;
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// map filenames to build-ids.
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std::unordered_map<string, string> filename_to_build_id_;
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struct {
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int64 samples = 0;
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int64 missing_main_mmap = 0;
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int64 missing_sample_mmap = 0;
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int64 callchain_ips = 0;
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int64 missing_callchain_mmap = 0;
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int64 branch_stack_ips = 0;
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int64 missing_branch_stack_mmap = 0;
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int64 no_event_errors = 0;
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} stat_;
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};
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void Normalizer::UpdateMapsWithForkEvent(
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const quipper::PerfDataProto_ForkEvent& fork) {
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if (fork.pid() == fork.ppid()) {
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// Don't care about threads.
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return;
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}
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const auto& it = pid_to_mmaps_.find(fork.ppid());
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if (it != pid_to_mmaps_.end()) {
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pid_to_mmaps_[fork.pid()] = std::unique_ptr<MMapIntervalMap>(
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new MMapIntervalMap(*it->second.get()));
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}
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auto comm_it = pid_to_comm_event_.find(fork.ppid());
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if (comm_it != pid_to_comm_event_.end()) {
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pid_to_comm_event_[fork.pid()] = comm_it->second;
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}
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auto exec_mmap_it = pid_to_executable_mmap_.find(fork.ppid());
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if (exec_mmap_it != pid_to_executable_mmap_.end()) {
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pid_to_executable_mmap_[fork.pid()] = exec_mmap_it->second;
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}
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}
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inline bool HasPrefixString(const string& haystack, const char* needle) {
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const size_t needle_len = strlen(needle);
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const size_t haystack_len = haystack.length();
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return haystack_len >= needle_len &&
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haystack.compare(0, needle_len, needle) == 0;
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}
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inline bool HasSuffixString(const string& haystack, const char* needle) {
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const size_t needle_len = strlen(needle);
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const size_t haystack_len = haystack.length();
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return haystack_len >= needle_len &&
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haystack.compare(haystack_len - needle_len, needle_len, needle) == 0;
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}
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void Normalizer::Normalize() {
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for (const auto& event_proto : perf_proto_.events()) {
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if (event_proto.has_mmap_event()) {
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UpdateMapsWithMMapEvent(&event_proto.mmap_event());
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} else if (event_proto.has_comm_event()) {
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if (event_proto.comm_event().pid() == event_proto.comm_event().tid()) {
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// pid==tid happens on exec()
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pid_to_executable_mmap_.erase(event_proto.comm_event().pid());
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pid_to_comm_event_[event_proto.comm_event().pid()] =
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&event_proto.comm_event();
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}
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PerfDataHandler::CommContext comm_context;
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comm_context.comm = &event_proto.comm_event();
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handler_->Comm(comm_context);
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} else if (event_proto.has_fork_event()) {
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UpdateMapsWithForkEvent(event_proto.fork_event());
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} else if (event_proto.has_lost_event()) {
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stat_.samples += event_proto.lost_event().lost();
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stat_.missing_main_mmap += event_proto.lost_event().lost();
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stat_.missing_sample_mmap += event_proto.lost_event().lost();
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quipper::PerfDataProto::SampleEvent sample;
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quipper::PerfDataProto::EventHeader header;
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sample.set_id(event_proto.lost_event().id());
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sample.set_pid(event_proto.lost_event().sample_info().pid());
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sample.set_tid(event_proto.lost_event().sample_info().tid());
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PerfDataHandler::SampleContext context(header, sample);
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context.file_attrs_index = GetEventIndexForSample(sample);
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if (context.file_attrs_index == -1) {
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++stat_.no_event_errors;
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continue;
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}
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for (uint64 i = 0; i < event_proto.lost_event().lost(); ++i) {
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handler_->Sample(context);
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}
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} else if (event_proto.has_sample_event()) {
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InvokeHandleSample(event_proto);
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}
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}
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LogStats();
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}
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void Normalizer::InvokeHandleSample(
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const quipper::PerfDataProto::PerfEvent& event_proto) {
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if (!event_proto.has_sample_event()) {
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std::cerr << "Expected sample event." << std::endl;
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abort();
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}
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const auto& sample = event_proto.sample_event();
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PerfDataHandler::SampleContext context(event_proto.header(),
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event_proto.sample_event());
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context.file_attrs_index = GetEventIndexForSample(context.sample);
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if (context.file_attrs_index == -1) {
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++stat_.no_event_errors;
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return;
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}
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++stat_.samples;
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uint32 pid = sample.pid();
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context.sample_mapping = GetMappingFromPidAndIP(pid, sample.ip());
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stat_.missing_sample_mmap += context.sample_mapping == nullptr;
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context.main_mapping = GetMainMMapFromPid(pid);
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std::unique_ptr<PerfDataHandler::Mapping> fake;
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// Kernel samples might take some extra work.
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if (context.main_mapping == nullptr &&
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(event_proto.header().misc() & PERF_RECORD_MISC_CPUMODE_MASK) ==
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PERF_RECORD_MISC_KERNEL) {
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auto comm_it = pid_to_comm_event_.find(pid);
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auto kernel_it = pid_to_executable_mmap_.find(-1);
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if (comm_it != pid_to_comm_event_.end()) {
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const string* build_id = nullptr;
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if (kernel_it != pid_to_executable_mmap_.end()) {
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build_id = kernel_it->second->build_id;
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}
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fake.reset(new PerfDataHandler::Mapping(&comm_it->second->comm(),
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build_id, 0, 1, 0, 0));
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context.main_mapping = fake.get();
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} else if (pid == 0 && kernel_it != pid_to_executable_mmap_.end()) {
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context.main_mapping = kernel_it->second;
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}
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}
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stat_.missing_main_mmap += context.main_mapping == nullptr;
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// Normalize the callchain.
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context.callchain.resize(sample.callchain_size());
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for (int i = 0; i < sample.callchain_size(); ++i) {
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++stat_.callchain_ips;
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context.callchain[i].ip = sample.callchain(i);
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context.callchain[i].mapping =
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GetMappingFromPidAndIP(pid, sample.callchain(i));
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stat_.missing_callchain_mmap += context.callchain[i].mapping == nullptr;
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}
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// Normalize the branch_stack.
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context.branch_stack.resize(sample.branch_stack_size());
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for (int i = 0; i < sample.branch_stack_size(); ++i) {
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stat_.branch_stack_ips += 2;
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auto bse = sample.branch_stack(i);
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// from
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context.branch_stack[i].from.ip = bse.from_ip();
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context.branch_stack[i].from.mapping =
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GetMappingFromPidAndIP(pid, bse.from_ip());
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stat_.missing_branch_stack_mmap +=
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context.branch_stack[i].from.mapping == nullptr;
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// to
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context.branch_stack[i].to.ip = bse.to_ip();
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context.branch_stack[i].to.mapping =
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GetMappingFromPidAndIP(pid, bse.to_ip());
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stat_.missing_branch_stack_mmap +=
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context.branch_stack[i].to.mapping == nullptr;
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// mispredicted
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context.branch_stack[i].mispredicted = bse.mispredicted();
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}
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handler_->Sample(context);
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}
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static void CheckStat(int64 num, int64 denom, const string& desc) {
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const int max_missing_pct = 1;
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if (denom > 0 && num * 100 / denom > max_missing_pct) {
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LOG(ERROR) << "stat: " << desc << " " << num << "/" << denom;
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}
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}
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void Normalizer::LogStats() {
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CheckStat(stat_.missing_main_mmap, stat_.samples, "missing_main_mmap");
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CheckStat(stat_.missing_sample_mmap, stat_.samples, "missing_sample_mmap");
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CheckStat(stat_.missing_callchain_mmap, stat_.callchain_ips,
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"missing_callchain_mmap");
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CheckStat(stat_.missing_branch_stack_mmap, stat_.branch_stack_ips,
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"missing_branch_stack_mmap");
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CheckStat(stat_.no_event_errors, 1, "unknown event id");
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}
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static bool IsVirtualMapping(const string& map_name) {
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return HasPrefixString(map_name, "//") ||
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(HasPrefixString(map_name, "[") && HasSuffixString(map_name, "]"));
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}
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void Normalizer::UpdateMapsWithMMapEvent(
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const quipper::PerfDataProto_MMapEvent* mmap) {
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if (mmap->len() == 0) {
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LOG(WARNING) << "bogus mapping: " << mmap->filename();
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return;
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}
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uint32 pid = mmap->pid();
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MMapIntervalMap* interval_map = nullptr;
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const auto& it = pid_to_mmaps_.find(pid);
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if (it == pid_to_mmaps_.end()) {
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interval_map = new MMapIntervalMap;
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pid_to_mmaps_[pid] = std::unique_ptr<MMapIntervalMap>(interval_map);
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} else {
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interval_map = it->second.get();
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}
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std::unordered_map<string, string>::const_iterator build_id_it;
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if (mmap->filename() != "") {
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build_id_it = filename_to_build_id_.find(mmap->filename());
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} else {
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std::stringstream filename;
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filename << std::hex << mmap->filename_md5_prefix();
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build_id_it = filename_to_build_id_.find(filename.str());
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}
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const string* build_id = build_id_it == filename_to_build_id_.end()
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? nullptr
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: &build_id_it->second;
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PerfDataHandler::Mapping* mapping = new PerfDataHandler::Mapping(
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&mmap->filename(), build_id, mmap->start(), mmap->start() + mmap->len(),
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mmap->pgoff(), mmap->filename_md5_prefix());
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owned_mappings_.emplace_back(mapping);
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if (mapping->file_offset > (static_cast<uint64>(1) << 63) &&
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mapping->limit > (static_cast<uint64>(1) << 63)) {
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// kernel is funky and basically swaps start and offset. Arrange
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// them such that we can reasonably symbolize them later.
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uint64 old_start = mapping->start;
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// file_offset here actually refers to the address of the _stext
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// kernel symbol, so we need to align it.
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mapping->start = mapping->file_offset - mapping->file_offset % 4096;
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mapping->file_offset = old_start;
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}
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interval_map->Set(mapping->start, mapping->limit, mapping);
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// Pass the final mapping through to the subclass also.
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PerfDataHandler::MMapContext mmap_context;
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mmap_context.pid = pid;
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mmap_context.mapping = mapping;
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handler_->MMap(mmap_context);
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// Main executables are usually loaded at 0x8048000 or 0x400000.
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// If we ever see an MMAP starting at one of those locations, that should be
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// our guess.
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// This is true even if the old MMAP started at one of the locations, because
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// the pid may have been recycled since then (so newer is better).
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if (mapping->start == 0x8048000 || mapping->start == 0x400000) {
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pid_to_executable_mmap_[pid] = mapping;
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return;
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}
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// Figure out whether this MMAP is the main executable.
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// If there have been no previous MMAPs for this pid, then this MMAP is our
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// best guess.
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auto old_mapping_it = pid_to_executable_mmap_.find(pid);
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PerfDataHandler::Mapping* old_mapping =
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old_mapping_it == pid_to_executable_mmap_.end() ? nullptr
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: old_mapping_it->second;
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if (old_mapping != nullptr && old_mapping->start == 0x400000 &&
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(old_mapping->filename == nullptr || *old_mapping->filename == "") &&
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mapping->start - mapping->file_offset == 0x400000) {
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// Hugepages remap the main binary, but the original mapping loses
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// its name, so we have this hack.
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old_mapping->filename = &mmap->filename();
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}
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static const char kKernelPrefix[] = "[kernel.kallsyms]";
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if (old_mapping == nullptr && !HasSuffixString(mmap->filename(), ".ko") &&
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!HasSuffixString(mmap->filename(), ".so") &&
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!IsDeletedSharedObject(mmap->filename()) &&
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!IsVersionedSharedObject(mmap->filename()) &&
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!IsVirtualMapping(mmap->filename()) &&
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!HasPrefixString(mmap->filename(), kKernelPrefix)) {
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if (!HasPrefixString(mmap->filename(), "/usr/bin") &&
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!HasPrefixString(mmap->filename(), "/usr/sbin") &&
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!HasSuffixString(mmap->filename(), "/sel_ldr")) {
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LOG(INFO) << "guessing main for pid: " << pid << " " << mmap->filename();
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}
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pid_to_executable_mmap_[pid] = mapping;
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return;
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}
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if (pid == std::numeric_limits<uint32>::max() &&
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HasPrefixString(mmap->filename(), kKernelPrefix)) {
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pid_to_executable_mmap_[pid] = mapping;
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}
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}
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const PerfDataHandler::Mapping* Normalizer::TryLookupInPid(uint32 pid,
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uint64 ip) const {
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const auto& it = pid_to_mmaps_.find(pid);
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if (it == pid_to_mmaps_.end()) {
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VLOG(2) << "No mmaps for pid " << pid;
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return nullptr;
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}
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MMapIntervalMap* mmaps = it->second.get();
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const PerfDataHandler::Mapping* mapping = nullptr;
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mmaps->Lookup(ip, &mapping);
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return mapping;
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}
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// Find the mapping for ip in the context of pid. We might be looking
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// at a kernel IP, however (which can show up in any pid, and are
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// stored in our map as pid = -1), so check there if the lookup fails
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// in our process.
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const PerfDataHandler::Mapping* Normalizer::GetMappingFromPidAndIP(
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uint32 pid, uint64 ip) const {
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if (ip >= PERF_CONTEXT_MAX) {
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// These aren't real IPs, they're context hints. Drop them.
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return nullptr;
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}
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// One could try to decide if this is a kernel or user sample
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// directly. ahh@ thinks there's a heuristic that should work on
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// x86 (basically without any error): all kernel samples should have
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// 16 high bits set, all user samples should have high 16 bits
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// cleared. But that's not portable, and on any arch (...hopefully)
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// the user/kernel mappings should be disjoint anyway, so just check
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// both, starting with user. We could also use PERF_CONTEXT_KERNEL
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// and friends (see for instance how perf handles this:
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// https://goto.google.com/udgor) to know whether to check user or
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// kernel, but this seems more robust.
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const PerfDataHandler::Mapping* mapping = TryLookupInPid(pid, ip);
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if (mapping == nullptr) {
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// Might be a kernel sample.
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mapping = TryLookupInPid(-1, ip);
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}
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if (mapping == nullptr) {
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VLOG(2) << "no sample mmap found for pid " << pid << " and ip " << ip;
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return nullptr;
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}
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if (ip < mapping->start || ip >= mapping->limit) {
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std::cerr << "IP is not in mapping." << std::endl
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<< "IP: " << ip << std::endl
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<< "Start: " << mapping->start << std::endl
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<< "Limit: " << mapping->limit << std::endl;
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abort();
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}
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return mapping;
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}
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const PerfDataHandler::Mapping* Normalizer::GetMainMMapFromPid(
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uint32 pid) const {
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auto mapping_it = pid_to_executable_mmap_.find(pid);
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if (mapping_it != pid_to_executable_mmap_.end()) {
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return mapping_it->second;
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}
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VLOG(2) << "No argv0 name found for sample with pid: " << pid;
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return nullptr;
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}
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int64 Normalizer::GetEventIndexForSample(
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const quipper::PerfDataProto_SampleEvent& sample) const {
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if (perf_proto_.file_attrs().size() == 1) {
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return 0;
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}
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if (!sample.has_id()) {
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LOG(ERROR) << "Perf sample did not have id";
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return -1;
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}
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auto it = id_to_event_index_.find(sample.id());
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if (it == id_to_event_index_.end()) {
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LOG(ERROR) << "Incorrect event id: " << sample.id();
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return -1;
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}
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return it->second;
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}
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} // namespace
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// Finds needle in haystack starting at cursor. It then returns the index
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// directly after needle or string::npos if needle was not found.
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size_t FindAfter(const string& haystack, const string& needle, size_t cursor) {
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auto next_cursor = haystack.find(needle, cursor);
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if (next_cursor != string::npos) {
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next_cursor += needle.size();
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}
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return next_cursor;
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}
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bool IsDeletedSharedObject(const string& path) {
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size_t cursor = 1;
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while ((cursor = FindAfter(path, ".so", cursor)) != string::npos) {
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const auto ch = path.at(cursor);
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if (ch == '.' || ch == '_' || ch == ' ') {
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return path.find("(deleted)", cursor) != string::npos;
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}
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}
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return false;
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}
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bool IsVersionedSharedObject(const string& path) {
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return path.find(".so.", 1) != string::npos;
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}
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PerfDataHandler::PerfDataHandler() {}
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void PerfDataHandler::Process(const quipper::PerfDataProto& perf_proto,
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PerfDataHandler* handler) {
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Normalizer Normalizer(perf_proto, handler);
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return Normalizer.Normalize();
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}
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|
} // namespace perftools
|
