Adapt perf package to our needs

LICENSE

@@ -0,0 +1,27 @@
+Copyright (c) 2009 The Go 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.

README.md

@@ -1,3 +1,17 @@
+----
+
+This is a clone of the `golang.org/x/sys/unix/linux/perf` submitted by
+[acln0](https://github.com/acln0) to review at
+https://go-review.googlesource.com/c/sys/+/168059
+
+An alternative working tree for this package can also be found
+at https://github.com/acln0/perf
+
+This Elastic fork contains bugfixes and features necessary for
+our KProbes implementation.
+
+----
+
 `perf` API client package for Linux. See `man 2 perf_event_open` and
 `include/uapi/linux/perf_event.h`.
 

count.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build linux
+
 package perf
 
 import (

group.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build linux
+
 package perf
 
 import (

perf.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build linux
+
 package perf
 
 import (
@@ -12,6 +14,7 @@ import (
 	"path/filepath"
 	"strconv"
 	"sync"
+	"sync/atomic"
 	"syscall"
 	"time"
 	"unsafe"
@@ -92,6 +95,11 @@ type Event struct {
 	// pollresp receives responses from the poll goroutine associated
 	// with the ring, back to ReadRawRecord.
 	pollresp chan pollresp
+
+	// recordBuffer is used as storage for records returned by ReadRecord
+	// and ReadRawRecord. This means memory for records returned from those
+	// methods will be overwritten by successive calls.
+	recordBuffer []byte
 }
 
 // Open opens the event configured by attr.
@@ -121,6 +129,12 @@ func Open(a *Attr, pid, cpu int, group *Event) (*Event, error) {
 	return open(a, pid, cpu, group, 0)
 }
 
+// OpenWithFlags is like Open but allows to specify additional flags to be
+// passed to perf_event_open(2).
+func OpenWithFlags(a *Attr, pid, cpu int, group *Event, flags int) (*Event, error) {
+	return open(a, pid, cpu, group, flags)
+}
+
 // OpenCGroup is like Open, but activates per-container system-wide
 // monitoring. If cgroupfs is mounted on /dev/cgroup, and the group to
 // monitor is called "test", then cgroupfd must be a file descriptor opened
@@ -233,7 +247,8 @@ func (ev *Event) MapRingNumPages(num int) error {
 		return nil
 	}
 
-	size := (1 + num) * unix.Getpagesize()
+	pgSize := unix.Getpagesize()
+	size := (1 + num) * pgSize
 	const prot = unix.PROT_READ | unix.PROT_WRITE
 	const flags = unix.MAP_SHARED
 	ring, err := unix.Mmap(ev.perffd, 0, size, prot, flags)
@@ -248,8 +263,8 @@ func (ev *Event) MapRingNumPages(num int) error {
 	// observed to do this. Try to detect this condition, and adjust
 	// the values accordingly.
 	if meta.Data_offset == 0 && meta.Data_size == 0 {
-		meta.Data_offset = uint64(unix.Getpagesize())
-		meta.Data_size = uint64(num) * meta.Data_offset
+		atomic.StoreUint64(&meta.Data_offset, uint64(pgSize))
+		atomic.StoreUint64(&meta.Data_size, uint64(num*pgSize))
 	}
 
 	ringdata := ring[meta.Data_offset:]

perf_example_test.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build linux
+
 package perf_test
 
 import (

perf_test.go

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build linux
+
 package perf_test
 
 import (