[llvm-profgen] Add support for Linux kenrel profile #92831
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Add the support to handle Linux kernel perf files. The functionality is under option -kernel. Note that currently only main kernel (in vmlinux) is handled: kernel modules are not handled.
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@llvm/pr-subscribers-pgo Author: None (xur-llvm) ChangesAdd the support to handle Linux kernel perf files. The functionality is under option -kernel. Note that currently only main kernel (in vmlinux) is handled: kernel modules are not handled. Full diff: https://github.com/llvm/llvm-project/pull/92831.diff 4 Files Affected:
diff --git a/llvm/tools/llvm-profgen/PerfReader.cpp b/llvm/tools/llvm-profgen/PerfReader.cpp
index e9442027aed3f..36c8ebd6af566 100644
--- a/llvm/tools/llvm-profgen/PerfReader.cpp
+++ b/llvm/tools/llvm-profgen/PerfReader.cpp
@@ -321,7 +321,7 @@ bool VirtualUnwinder::unwind(const PerfSample *Sample, uint64_t Repeat) {
std::unique_ptr<PerfReaderBase>
PerfReaderBase::create(ProfiledBinary *Binary, PerfInputFile &PerfInput,
- std::optional<uint32_t> PIDFilter) {
+ std::optional<int32_t> PIDFilter) {
std::unique_ptr<PerfReaderBase> PerfReader;
if (PerfInput.Format == PerfFormat::UnsymbolizedProfile) {
@@ -355,7 +355,7 @@ PerfReaderBase::create(ProfiledBinary *Binary, PerfInputFile &PerfInput,
PerfInputFile
PerfScriptReader::convertPerfDataToTrace(ProfiledBinary *Binary,
PerfInputFile &File,
- std::optional<uint32_t> PIDFilter) {
+ std::optional<int32_t> PIDFilter) {
StringRef PerfData = File.InputFile;
// Run perf script to retrieve PIDs matching binary we're interested in.
auto PerfExecutable = sys::Process::FindInEnvPath("PATH", "perf");
@@ -363,49 +363,61 @@ PerfScriptReader::convertPerfDataToTrace(ProfiledBinary *Binary,
exitWithError("Perf not found.");
}
std::string PerfPath = *PerfExecutable;
-
SmallString<128> PerfTraceFile;
sys::fs::createUniquePath("perf-script-%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%.tmp",
PerfTraceFile, /*MakeAbsolute=*/true);
std::string ErrorFile = std::string(PerfTraceFile) + ".err";
- StringRef ScriptMMapArgs[] = {PerfPath, "script", "--show-mmap-events",
- "-F", "comm,pid", "-i",
- PerfData};
std::optional<StringRef> Redirects[] = {std::nullopt, // Stdin
StringRef(PerfTraceFile), // Stdout
StringRef(ErrorFile)}; // Stderr
- sys::ExecuteAndWait(PerfPath, ScriptMMapArgs, std::nullopt, Redirects);
-
PerfScriptReader::TempFileCleanups.emplace_back(PerfTraceFile);
PerfScriptReader::TempFileCleanups.emplace_back(ErrorFile);
- // Collect the PIDs
- TraceStream TraceIt(PerfTraceFile);
+ // For a kernel perf file, we assume --branch_filter=k is used. So there is
+ // no need for PIDs.
std::string PIDs;
- std::unordered_set<uint32_t> PIDSet;
- while (!TraceIt.isAtEoF()) {
- MMapEvent MMap;
- if (isMMap2Event(TraceIt.getCurrentLine()) &&
- extractMMap2EventForBinary(Binary, TraceIt.getCurrentLine(), MMap)) {
- auto It = PIDSet.emplace(MMap.PID);
- if (It.second && (!PIDFilter || MMap.PID == *PIDFilter)) {
- if (!PIDs.empty()) {
- PIDs.append(",");
+ if (!Binary->isKernel()) {
+ StringRef ScriptMMapArgs[] = {PerfPath, "script", "--show-mmap-events",
+ "-F", "comm,pid", "-i",
+ PerfData};
+ sys::ExecuteAndWait(PerfPath, ScriptMMapArgs, std::nullopt, Redirects);
+
+ // Collect the PIDs
+ TraceStream TraceIt(PerfTraceFile);
+ std::unordered_set<int32_t> PIDSet;
+ while (!TraceIt.isAtEoF()) {
+ MMapEvent MMap;
+ if (isMMapEvent(TraceIt.getCurrentLine()) &&
+ extractMMapEventForBinary(Binary, TraceIt.getCurrentLine(), MMap)) {
+ auto It = PIDSet.emplace(MMap.PID);
+ if (It.second && (!PIDFilter || MMap.PID == *PIDFilter)) {
+ if (!PIDs.empty()) {
+ PIDs.append(",");
+ }
+ PIDs.append(utostr(MMap.PID));
}
- PIDs.append(utostr(MMap.PID));
}
+ TraceIt.advance();
}
- TraceIt.advance();
- }
- if (PIDs.empty()) {
- exitWithError("No relevant mmap event is found in perf data.");
+ if (PIDs.empty()) {
+ exitWithError("No relevant mmap event is found in perf data.");
+ }
}
// Run perf script again to retrieve events for PIDs collected above
- StringRef ScriptSampleArgs[] = {PerfPath, "script", "--show-mmap-events",
- "-F", "ip,brstack", "--pid",
- PIDs, "-i", PerfData};
+ SmallVector<StringRef, 8> ScriptSampleArgs;
+ ScriptSampleArgs.push_back(PerfPath);
+ ScriptSampleArgs.push_back("script");
+ ScriptSampleArgs.push_back("--show-mmap-events");
+ ScriptSampleArgs.push_back("-F");
+ ScriptSampleArgs.push_back("ip,brstack");
+ ScriptSampleArgs.push_back("-i");
+ ScriptSampleArgs.push_back(PerfData);
+ if (!PIDs.empty()) {
+ ScriptSampleArgs.push_back("--pid");
+ ScriptSampleArgs.push_back(PIDs);
+ }
sys::ExecuteAndWait(PerfPath, ScriptSampleArgs, std::nullopt, Redirects);
return {std::string(PerfTraceFile), PerfFormat::PerfScript,
@@ -428,7 +440,10 @@ static StringRef filename(StringRef Path, bool UseBackSlash) {
void PerfScriptReader::updateBinaryAddress(const MMapEvent &Event) {
// Drop the event which doesn't belong to user-provided binary
StringRef BinaryName = filename(Event.BinaryPath, Binary->isCOFF());
- if (Binary->getName() != BinaryName)
+ bool IsKernel = Binary->isKernel();
+ if (!IsKernel && Binary->getName() != BinaryName)
+ return;
+ if (IsKernel && !Binary->isKernelImageName(BinaryName))
return;
// Drop the event if process does not match pid filter
@@ -441,7 +456,7 @@ void PerfScriptReader::updateBinaryAddress(const MMapEvent &Event) {
return;
}
- if (Event.Offset == Binary->getTextSegmentOffset()) {
+ if (IsKernel || Event.Offset == Binary->getTextSegmentOffset()) {
// A binary image could be unloaded and then reloaded at different
// place, so update binary load address.
// Only update for the first executable segment and assume all other
@@ -950,16 +965,23 @@ void PerfScriptReader::parseSample(TraceStream &TraceIt) {
parseSample(TraceIt, Count);
}
-bool PerfScriptReader::extractMMap2EventForBinary(ProfiledBinary *Binary,
- StringRef Line,
- MMapEvent &MMap) {
- // Parse a line like:
+bool PerfScriptReader::extractMMapEventForBinary(ProfiledBinary *Binary,
+ StringRef Line,
+ MMapEvent &MMap) {
+ // Parse a MMap2 line like:
// PERF_RECORD_MMAP2 2113428/2113428: [0x7fd4efb57000(0x204000) @ 0
// 08:04 19532229 3585508847]: r-xp /usr/lib64/libdl-2.17.so
- constexpr static const char *const Pattern =
- "PERF_RECORD_MMAP2 ([0-9]+)/[0-9]+: "
+ constexpr static const char *const MMap2Pattern =
+ "PERF_RECORD_MMAP2 (-?[0-9]+)/[0-9]+: "
"\\[(0x[a-f0-9]+)\\((0x[a-f0-9]+)\\) @ "
"(0x[a-f0-9]+|0) .*\\]: [-a-z]+ (.*)";
+ // Parse a MMap line like
+ // PERF_RECORD_MMAP -1/0: [0xffffffff81e00000(0x3e8fa000) @ \
+ // 0xffffffff81e00000]: x [kernel.kallsyms]_text
+ constexpr static const char *const MMapPattern =
+ "PERF_RECORD_MMAP (-?[0-9]+)/[0-9]+: "
+ "\\[(0x[a-f0-9]+)\\((0x[a-f0-9]+)\\) @ "
+ "(0x[a-f0-9]+|0)\\]: [-a-z]+ (.*)";
// Field 0 - whole line
// Field 1 - PID
// Field 2 - base address
@@ -975,14 +997,25 @@ bool PerfScriptReader::extractMMap2EventForBinary(ProfiledBinary *Binary,
BINARY_PATH = 5
};
- Regex RegMmap2(Pattern);
+ bool R = false;
SmallVector<StringRef, 6> Fields;
- bool R = RegMmap2.match(Line, &Fields);
+ if (Line.contains("PERF_RECORD_MMAP2 ")) {
+ Regex RegMmap2(MMap2Pattern);
+ R = RegMmap2.match(Line, &Fields);
+ } else if (Line.contains("PERF_RECORD_MMAP ")) {
+ Regex RegMmap(MMapPattern);
+ R = RegMmap.match(Line, &Fields);
+ } else
+ llvm_unreachable("unexpected MMAP event entry");
+
if (!R) {
std::string WarningMsg = "Cannot parse mmap event: " + Line.str() + " \n";
WithColor::warning() << WarningMsg;
+ return false;
}
- Fields[PID].getAsInteger(10, MMap.PID);
+ long long MMapPID = 0;
+ getAsSignedInteger(Fields[PID], 10, MMapPID);
+ MMap.PID = MMapPID;
Fields[MMAPPED_ADDRESS].getAsInteger(0, MMap.Address);
Fields[MMAPPED_SIZE].getAsInteger(0, MMap.Size);
Fields[PAGE_OFFSET].getAsInteger(0, MMap.Offset);
@@ -993,19 +1026,22 @@ bool PerfScriptReader::extractMMap2EventForBinary(ProfiledBinary *Binary,
}
StringRef BinaryName = filename(MMap.BinaryPath, Binary->isCOFF());
+ if (Binary->isKernel()) {
+ return Binary->isKernelImageName(BinaryName);
+ }
return Binary->getName() == BinaryName;
}
-void PerfScriptReader::parseMMap2Event(TraceStream &TraceIt) {
+void PerfScriptReader::parseMMapEvent(TraceStream &TraceIt) {
MMapEvent MMap;
- if (extractMMap2EventForBinary(Binary, TraceIt.getCurrentLine(), MMap))
+ if (extractMMapEventForBinary(Binary, TraceIt.getCurrentLine(), MMap))
updateBinaryAddress(MMap);
TraceIt.advance();
}
void PerfScriptReader::parseEventOrSample(TraceStream &TraceIt) {
- if (isMMap2Event(TraceIt.getCurrentLine()))
- parseMMap2Event(TraceIt);
+ if (isMMapEvent(TraceIt.getCurrentLine()))
+ parseMMapEvent(TraceIt);
else
parseSample(TraceIt);
}
@@ -1032,7 +1068,7 @@ bool PerfScriptReader::isLBRSample(StringRef Line) {
return false;
}
-bool PerfScriptReader::isMMap2Event(StringRef Line) {
+bool PerfScriptReader::isMMapEvent(StringRef Line) {
// Short cut to avoid string find is possible.
if (Line.empty() || Line.size() < 50)
return false;
@@ -1040,9 +1076,9 @@ bool PerfScriptReader::isMMap2Event(StringRef Line) {
if (std::isdigit(Line[0]))
return false;
- // PERF_RECORD_MMAP2 does not appear at the beginning of the line
- // for ` perf script --show-mmap-events -i ...`
- return Line.contains("PERF_RECORD_MMAP2");
+ // PERF_RECORD_MMAP2 or PERF_RECORD_MMAP does not appear at the beginning of
+ // the line for ` perf script --show-mmap-events -i ...`
+ return Line.contains("PERF_RECORD_MMAP");
}
// The raw hybird sample is like
diff --git a/llvm/tools/llvm-profgen/PerfReader.h b/llvm/tools/llvm-profgen/PerfReader.h
index b821cbe13efae..2366479c38941 100644
--- a/llvm/tools/llvm-profgen/PerfReader.h
+++ b/llvm/tools/llvm-profgen/PerfReader.h
@@ -570,7 +570,7 @@ class PerfReaderBase {
virtual ~PerfReaderBase() = default;
static std::unique_ptr<PerfReaderBase>
create(ProfiledBinary *Binary, PerfInputFile &PerfInput,
- std::optional<uint32_t> PIDFilter);
+ std::optional<int32_t> PIDFilter);
// Entry of the reader to parse multiple perf traces
virtual void parsePerfTraces() = 0;
@@ -595,15 +595,15 @@ class PerfReaderBase {
class PerfScriptReader : public PerfReaderBase {
public:
PerfScriptReader(ProfiledBinary *B, StringRef PerfTrace,
- std::optional<uint32_t> PID)
- : PerfReaderBase(B, PerfTrace), PIDFilter(PID){};
+ std::optional<int32_t> PID)
+ : PerfReaderBase(B, PerfTrace), PIDFilter(PID) {};
// Entry of the reader to parse multiple perf traces
void parsePerfTraces() override;
// Generate perf script from perf data
- static PerfInputFile
- convertPerfDataToTrace(ProfiledBinary *Binary, PerfInputFile &File,
- std::optional<uint32_t> PIDFilter);
+ static PerfInputFile convertPerfDataToTrace(ProfiledBinary *Binary,
+ PerfInputFile &File,
+ std::optional<int32_t> PIDFilter);
// Extract perf script type by peaking at the input
static PerfContent checkPerfScriptType(StringRef FileName);
@@ -615,7 +615,7 @@ class PerfScriptReader : public PerfReaderBase {
protected:
// The parsed MMap event
struct MMapEvent {
- uint64_t PID = 0;
+ int64_t PID = 0;
uint64_t Address = 0;
uint64_t Size = 0;
uint64_t Offset = 0;
@@ -625,15 +625,15 @@ class PerfScriptReader : public PerfReaderBase {
// Check whether a given line is LBR sample
static bool isLBRSample(StringRef Line);
// Check whether a given line is MMAP event
- static bool isMMap2Event(StringRef Line);
- // Parse a single line of a PERF_RECORD_MMAP2 event looking for a
+ static bool isMMapEvent(StringRef Line);
+ // Parse a single line of a PERF_RECORD_MMAP event looking for a
// mapping between the binary name and its memory layout.
- static bool extractMMap2EventForBinary(ProfiledBinary *Binary, StringRef Line,
- MMapEvent &MMap);
+ static bool extractMMapEventForBinary(ProfiledBinary *Binary, StringRef Line,
+ MMapEvent &MMap);
// Update base address based on mmap events
void updateBinaryAddress(const MMapEvent &Event);
// Parse mmap event and update binary address
- void parseMMap2Event(TraceStream &TraceIt);
+ void parseMMapEvent(TraceStream &TraceIt);
// Parse perf events/samples and do aggregation
void parseAndAggregateTrace();
// Parse either an MMAP event or a perf sample
@@ -669,7 +669,7 @@ class PerfScriptReader : public PerfReaderBase {
// Keep track of all invalid return addresses
std::set<uint64_t> InvalidReturnAddresses;
// PID for the process of interest
- std::optional<uint32_t> PIDFilter;
+ std::optional<int32_t> PIDFilter;
};
/*
@@ -681,8 +681,8 @@ class PerfScriptReader : public PerfReaderBase {
class LBRPerfReader : public PerfScriptReader {
public:
LBRPerfReader(ProfiledBinary *Binary, StringRef PerfTrace,
- std::optional<uint32_t> PID)
- : PerfScriptReader(Binary, PerfTrace, PID){};
+ std::optional<int32_t> PID)
+ : PerfScriptReader(Binary, PerfTrace, PID) {};
// Parse the LBR only sample.
void parseSample(TraceStream &TraceIt, uint64_t Count) override;
};
@@ -699,8 +699,8 @@ class LBRPerfReader : public PerfScriptReader {
class HybridPerfReader : public PerfScriptReader {
public:
HybridPerfReader(ProfiledBinary *Binary, StringRef PerfTrace,
- std::optional<uint32_t> PID)
- : PerfScriptReader(Binary, PerfTrace, PID){};
+ std::optional<int32_t> PID)
+ : PerfScriptReader(Binary, PerfTrace, PID) {};
// Parse the hybrid sample including the call and LBR line
void parseSample(TraceStream &TraceIt, uint64_t Count) override;
void generateUnsymbolizedProfile() override;
diff --git a/llvm/tools/llvm-profgen/ProfiledBinary.cpp b/llvm/tools/llvm-profgen/ProfiledBinary.cpp
index 1baf35820f97f..a7e506d32ac2e 100644
--- a/llvm/tools/llvm-profgen/ProfiledBinary.cpp
+++ b/llvm/tools/llvm-profgen/ProfiledBinary.cpp
@@ -56,6 +56,10 @@ static cl::list<std::string> DisassembleFunctions(
cl::desc("List of functions to print disassembly for. Accept demangled "
"names only. Only work with show-disassembly-only"));
+static cl::opt<bool>
+ KernelBinary("kernel",
+ cl::desc("Generate the profile for Linux kernel binary."));
+
extern cl::opt<bool> ShowDetailedWarning;
extern cl::opt<bool> InferMissingFrames;
@@ -221,6 +225,9 @@ void ProfiledBinary::load() {
LLVM_DEBUG(dbgs() << "Loading " << Path << "\n");
+ // Mark the binary as a kernel image;
+ IsKernel = KernelBinary;
+
// Find the preferred load address for text sections.
setPreferredTextSegmentAddresses(Obj);
diff --git a/llvm/tools/llvm-profgen/ProfiledBinary.h b/llvm/tools/llvm-profgen/ProfiledBinary.h
index 5d2088ad7691c..bf7c7e365bbad 100644
--- a/llvm/tools/llvm-profgen/ProfiledBinary.h
+++ b/llvm/tools/llvm-profgen/ProfiledBinary.h
@@ -291,6 +291,9 @@ class ProfiledBinary {
// Whether we need to symbolize all instructions to get function context size.
bool TrackFuncContextSize = false;
+ // Whether this is a kernel image;
+ bool IsKernel = false;
+
// Indicate if the base loading address is parsed from the mmap event or uses
// the preferred address
bool IsLoadedByMMap = false;
@@ -428,6 +431,14 @@ class ProfiledBinary {
bool usePseudoProbes() const { return UsePseudoProbes; }
bool useFSDiscriminator() const { return UseFSDiscriminator; }
+ bool isKernel() const { return IsKernel; }
+
+ bool isKernelImageName(StringRef BinaryName) const {
+ return BinaryName == "[kernel.kallsyms]" ||
+ BinaryName == "[kernel.kallsyms]_stext" ||
+ BinaryName == "[kernel.kallsyms]_text";
+ }
+
// Get the index in CodeAddressVec for the address
// As we might get an address which is not the code
// here it would round to the next valid code address by
|
|
Ping. |
WenleiHe
reviewed
Jun 6, 2024
| @@ -428,6 +431,14 @@ class ProfiledBinary { | |||
|
|
|||
| bool usePseudoProbes() const { return UsePseudoProbes; } | |||
| bool useFSDiscriminator() const { return UseFSDiscriminator; } | |||
| bool isKernel() const { return IsKernel; } | |||
|
|
|||
| bool isKernelImageName(StringRef BinaryName) const { | |||
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Why do we need a BinaryName parameter given ProfiledBinary has a name associated with it (getName)?
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getName() would return the binary name of the kernel image, typically vmlinux, or a name with version info, like vmlinux-6.8.0-smp-1201.1.889.0. The image name from perf command is in of the forms in this function.
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Ok, then this is static function?
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Right. I'll make it static.
| @@ -56,6 +56,10 @@ static cl::list<std::string> DisassembleFunctions( | |||
| cl::desc("List of functions to print disassembly for. Accept demangled " | |||
| "names only. Only work with show-disassembly-only")); | |||
|
|
|||
| static cl::opt<bool> | |||
| KernelBinary("kernel", | |||
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Given we assume kernel binary has specific names, do we need an extra flag to tell the tool to generate profile for kernel?
If we have this flag, what happens if the flag is used but binary provided doesn't match the predefined kernel binary name? Should we error out?
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I think this interface is easier than parsing the binary name. Usually the kernel image name is vmlinux.*. But there is a chance that an user image uses the same name. Or someone changes the kernel image name to whatever. I want users to confirm this is kernel perf data file by using the option.
If the user passes a wrong binary image, most like they won't get a profile because of the symbol and address mismatch.
Compared to AutoFDO's create_llvm_prof, llvm-profgen does not check the buildid. But that's separated issue. This patch is just the basic version that provides the kernel perf support.
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If the user passes a wrong binary image, most like they won't get a profile because of the symbol and address mismatch.
Maybe useful to error out if kernel is requested but binary is not kernel?
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That actually what I want to avoid -- I don't want to assume a fixed name for the kernel. For my kernel builds, I don't change anything and the kernel image is vmlinux.*. But I don't know if others will rename the image.
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What I meant is error out when kernel image isn't found in mmap (we're already assuming names there). But no big deal either way.
wlei-llvm
reviewed
Jun 6, 2024
| if (It.second && (!PIDFilter || MMap.PID == *PIDFilter)) { | ||
| if (!PIDs.empty()) { | ||
| PIDs.append(","); | ||
| if (!Binary->isKernel()) { |
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How about making this a function parameter and pass it from the caller? thinking this may be useful for other binary to skip the PID passing.
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Sure. I'll do that.
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Thanks. @wlei-llvm Done (by passing a parameter instead of call Binary->IsKernel())
Integrated Wenlei's review comments: (1) make retrieving the PID a function parameter. (2) make function isKernelImageName() a static function.
Integrated Wenlei's review comments: (1) make retrieving the PID a function parameter. (2) make function isKernelImageName() a static function. (3) error out if "--kernel" is given, but no corresponding mmap event is found (4) change "Binary->isKernel()" to a function parameter
Integrated Wenlei's review comments: (1) make retrieving the PID a function parameter. (2) make function isKernelImageName() a static function. (3) error out if "--kernel" is given, but no corresponding mmap event is found (4) change "Binary->isKernel()" to a function parameter
|
✅ With the latest revision this PR passed the C/C++ code formatter. |
|
Since @xur-llvm is on vacation till Jun, 25. I'll take over here. Thanks. |
Integrated Wenlei's review comments: (1) make retrieving the PID a function parameter. (2) make function isKernelImageName() a static function. (3) error out if "--kernel" is given, but no corresponding mmap event is found (4) change "Binary->isKernel()" to a function parameter
EthanLuisMcDonough
pushed a commit
to EthanLuisMcDonough/llvm-project
that referenced
this pull request
Aug 13, 2024
Add the support to handle Linux kernel perf files. The functionality is under option -kernel. Note that currently only main kernel (in vmlinux) is handled: kernel modules are not handled. --------- Co-authored-by: Han Shen <shenhan@google.com>
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Add the support to handle Linux kernel perf files. The functionality is under option -kernel. Note that currently only main kernel (in vmlinux) is handled: kernel modules are not handled.