v8/src/perf-jit.h
ssanfilippo 7d073b03c7 This commit is the first step towards emitting unwinding information in
the .eh_frame format as part of the jitdump generated when
FLAG_perf_prof is enabled. The final goal is allowing precise unwinding
of callchains that include JITted code when profiling V8 using perf.

Unwinding information is stored in the body of code objects after the
code itself, prefixed with its length and aligned to a 8-byte boundary.
A boolean flag in the header signals its presence, resulting in zero
memory overhead when the generation of unwinding info is disabled or
no such information was attached to the code object.

A new jitdump record type (with id 4) is introduced for specifying
optional unwinding information for code load records. The EhFrameHdr
struct is also introduced, together with a constructor to initialise it
from the associated code object.

At this stage no unwinding information is written to the jitdump, but
the infrastructure for doing so is ready in place.

BUG=v8:4899
LOG=N

Review-Url: https://codereview.chromium.org/1993653003
Cr-Commit-Position: refs/heads/master@{#37296}
2016-06-27 15:10:41 +00:00

127 lines
4.2 KiB
C++

// Copyright 2016 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef V8_PERF_JIT_H_
#define V8_PERF_JIT_H_
#include "src/log.h"
namespace v8 {
namespace internal {
#if V8_OS_LINUX
// Linux perf tool logging support
class PerfJitLogger : public CodeEventLogger {
public:
PerfJitLogger();
virtual ~PerfJitLogger();
void CodeMoveEvent(AbstractCode* from, Address to) override;
void CodeDisableOptEvent(AbstractCode* code,
SharedFunctionInfo* shared) override {}
private:
void OpenJitDumpFile();
void CloseJitDumpFile();
void* OpenMarkerFile(int fd);
void CloseMarkerFile(void* marker_address);
uint64_t GetTimestamp();
void LogRecordedBuffer(AbstractCode* code, SharedFunctionInfo* shared,
const char* name, int length) override;
// Extension added to V8 log file name to get the low-level log name.
static const char kFilenameFormatString[];
static const int kFilenameBufferPadding;
// File buffer size of the low-level log. We don't use the default to
// minimize the associated overhead.
static const int kLogBufferSize = 2 * MB;
void LogWriteBytes(const char* bytes, int size);
void LogWriteHeader();
void LogWriteDebugInfo(Code* code, SharedFunctionInfo* shared);
void LogWriteUnwindingInfo(Code* code);
static const uint32_t kElfMachIA32 = 3;
static const uint32_t kElfMachX64 = 62;
static const uint32_t kElfMachARM = 40;
static const uint32_t kElfMachMIPS = 10;
static const uint32_t kElfMachARM64 = 183;
uint32_t GetElfMach() {
#if V8_TARGET_ARCH_IA32
return kElfMachIA32;
#elif V8_TARGET_ARCH_X64
return kElfMachX64;
#elif V8_TARGET_ARCH_ARM
return kElfMachARM;
#elif V8_TARGET_ARCH_MIPS
return kElfMachMIPS;
#elif V8_TARGET_ARCH_ARM64
return kElfMachARM64;
#else
UNIMPLEMENTED();
return 0;
#endif
}
// Per-process singleton file. We assume that there is one main isolate;
// to determine when it goes away, we keep reference count.
static base::LazyRecursiveMutex file_mutex_;
static FILE* perf_output_handle_;
static uint64_t reference_count_;
static void* marker_address_;
static uint64_t code_index_;
};
#else
// PerfJitLogger is only implemented on Linux
class PerfJitLogger : public CodeEventLogger {
public:
void CodeMoveEvent(AbstractCode* from, Address to) override {
UNIMPLEMENTED();
}
void CodeDisableOptEvent(AbstractCode* code,
SharedFunctionInfo* shared) override {
UNIMPLEMENTED();
}
void LogRecordedBuffer(AbstractCode* code, SharedFunctionInfo* shared,
const char* name, int length) override {
UNIMPLEMENTED();
}
};
#endif // V8_OS_LINUX
} // namespace internal
} // namespace v8
#endif