linux-kernel - Re: [RFC][PATCH 00/12] various perf fixes

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Message-ID: <CACT4Y+byGyTjwdKsQfAK76ZhFOw3kik-pxOANW5APS4ot-+Y+Q@mail.gmail.com>
Date:	Mon, 15 Feb 2016 18:45:59 +0100
From:	Dmitry Vyukov <dvyukov@...gle.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Stephane Eranian <eranian@...gle.com>,
	LKML <linux-kernel@...r.kernel.org>, vince@...ter.net,
	Andi Kleen <andi@...stfloor.org>, jolsa@...hat.com,
	Thomas Gleixner <tglx@...utronix.de>,
	Arnaldo Carvalho de Melo <acme@...radead.org>
Subject: Re: [RFC][PATCH 00/12] various perf fixes

On Mon, Feb 15, 2016 at 6:07 PM, Peter Zijlstra <peterz@...radead.org> wrote:
> On Mon, Feb 15, 2016 at 06:04:15PM +0100, Dmitry Vyukov wrote:
>> There is something wrong and I guess it is not actually working.
>> Please post your config file so that I can double check. In
>> particular, did you set "cover": false?
>
>
> {
>         "http": "localhost:50000",
>         "workdir": "root/gopath/src/github.com/google/syzkaller/workdir",
>         "syzkaller": "/root/gopath/src/github.com/google/syzkaller",
>         "vmlinux": "-",
>         "type": "local",
>         "count": 1,
>         "procs": 160,
>         "cover": false,
>         "dropprivs": false,
>         "enable_syscalls": [
>                 "perf_event_open",
>                 "ioctl$PERF*",
>                 "prctl$void",
>                 "bpf$*",
>                 "sched_yield"
>         ]
> }


Ah, OK, it's actually working, everything is fine. You can double
check it by executing:

$ curl http://localhost:50000 | grep "exec total"

On my machine it produces (this is number of executed test programs per second):
exec total: 1196/sec<br>

However, you need to add getpid and gettid syscalls to the list of
enabled syscalls in config (they are required for perf_event_open):

        "enable_syscalls": [
                "getpid",
                "gettid",
                "perf_event_open",
                "ioctl$PERF*",
                "prctl$void",
                "bpf$*",
                "sched_yield"
        ]

(you can also add few other syscalls if you think they can be
relevant, but I am able to trigger perf crashes with just these)

And note that syz-manager binary won't notify you about any crashes,
you need to look in dmesg (and maybe at hanged processes).

I've collected some corpus of perf-related programs with coverage in
my setup. If you extract the attached archive into
root/gopath/src/github.com/google/syzkaller/workdir/corpus/ dir, it
should significantly speed up triggering of bugs (note that you did
not add / in front of the path, so it should be in your cwd).
While collecting the corpus I've triggered whole lot of crashes in few minutes:
https://gist.githubusercontent.com/dvyukov/9433b40adb094cc22cf2/raw/8642ad53ea44f604168189c568b419ba498dd5f3/gistfile1.txt

Download attachment "corpus.zip" of type "application/zip" (140780 bytes)