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