From: Mark Rutland <mark.rutland@arm.com>
To: Kyle Huey <me@kylehuey.com>, Vince Weaver <vincent.weaver@maine.edu>
Cc: "Jin, Yao" <yao.jin@linux.intel.com>,
Ingo Molnar <mingo@kernel.org>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
stable@vger.kernel.org,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
Jiri Olsa <jolsa@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Namhyung Kim <namhyung@kernel.org>,
Stephane Eranian <eranian@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
acme@kernel.org, jolsa@kernel.org, kan.liang@intel.com,
Will Deacon <will.deacon@arm.com>,
gregkh@linuxfoundation.org,
"Robert O'Callahan" <robert@ocallahan.org>,
open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] perf/core: generate overflow signal when samples are dropped (WAS: Re: [REGRESSION] perf/core: PMU interrupts dropped if we entered the kernel in the "skid" region)
Date: Wed, 28 Jun 2017 18:49:01 +0100 [thread overview]
Message-ID: <20170628174900.GG8252@leverpostej> (raw)
In-Reply-To: <CAP045ApjOeng6M9kqwbNpv5OTN=_Gkk2MHREztzZV_CecqpmxQ@mail.gmail.com>
On Wed, Jun 28, 2017 at 09:48:27AM -0700, Kyle Huey wrote:
> On Wed, Jun 28, 2017 at 3:56 AM, Mark Rutland <mark.rutland@arm.com> wrote:
> > @@ -6101,6 +6116,12 @@ void perf_prepare_sample(struct perf_event_header *header,
> > struct perf_output_handle handle;
> > struct perf_event_header header;
> >
> > + /*
> > + * For security, drop the skid kernel samples if necessary.
> > + */
> > + if (!sample_is_allowed(event, regs))
> > + return ret;
>
> Just a bare return here.
Ugh, yes. Sorry about that. I'll fix that up.
[...]
> I can confirm that with that fixed to compile, this patch fixes rr.
Thanks for giving this a go.
Having thought about this some more, I think Vince does make a good
point that throwing away samples is liable to break stuff, e.g. that
which only relies on (non-sensitive) samples.
It still seems wrong to make up data, though.
Maybe for exclude_kernel && !exclude_user events we can always generate
samples from the user regs, rather than the exception regs. That's going
to be closer to what the user wants, regardless. I'll take a look
tomorrow.
Thanks,
Mark.
next prev parent reply other threads:[~2017-06-28 17:50 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAP045Ap8cMx6mzSgcQ3n3bnh_8GJuCp7_KZe_5ZTCR_K6cPTLw@mail.gmail.com>
2017-06-28 1:01 ` [REGRESSION] perf/core: PMU interrupts dropped if we entered the kernel in the "skid" region Kyle Huey
2017-06-28 2:09 ` Jin, Yao
2017-06-28 4:51 ` Kyle Huey
2017-06-28 5:35 ` Jin, Yao
2017-06-28 7:30 ` Kyle Huey
2017-06-28 10:12 ` Mark Rutland
2017-06-28 10:56 ` [PATCH] perf/core: generate overflow signal when samples are dropped (WAS: Re: [REGRESSION] perf/core: PMU interrupts dropped if we entered the kernel in the "skid" region) Mark Rutland
2017-06-28 12:40 ` Vince Weaver
2017-06-28 13:07 ` Mark Rutland
2017-06-29 8:13 ` Alexey Budankov
2017-06-29 8:25 ` Alexey Budankov
2017-06-28 16:48 ` Kyle Huey
2017-06-28 17:49 ` Mark Rutland [this message]
2017-06-28 22:55 ` Kyle Huey
2017-06-29 0:27 ` Jin, Yao
2017-06-30 17:44 ` Kyle Huey
2017-07-04 9:03 ` Peter Zijlstra
2017-07-04 9:33 ` Mark Rutland
2017-07-04 9:46 ` Peter Zijlstra
2017-07-04 10:21 ` Mark Rutland
2017-07-06 5:07 ` Robert O'Callahan
2017-07-11 2:03 ` Kyle Huey
2017-07-11 9:03 ` Ingo Molnar
2017-07-11 13:07 ` Jin, Yao
2017-07-12 7:57 ` Ingo Molnar
2017-07-11 14:26 ` Mark Rutland
2017-07-11 15:32 ` Kyle Huey
2017-07-18 0:07 ` Kyle Huey
2017-06-29 8:12 ` Ingo Molnar
2017-07-04 9:06 ` Peter Zijlstra
2017-07-04 10:04 ` Ingo Molnar
2017-07-11 9:03 ` [tip:perf/urgent] Revert "perf/core: Drop kernel samples even though :u is specified" tip-bot for Ingo Molnar
2017-06-28 16:46 ` [REGRESSION] perf/core: PMU interrupts dropped if we entered the kernel in the "skid" region Kyle Huey
2017-06-28 17:19 ` Mark Rutland
2017-06-28 17:36 ` Kyle Huey
2017-06-28 17:52 ` Mark Rutland
2017-06-28 17:48 ` Robert O'Callahan
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20170628174900.GG8252@leverpostej \
--to=mark.rutland@arm.com \
--cc=acme@kernel.org \
--cc=acme@redhat.com \
--cc=alexander.shishkin@linux.intel.com \
--cc=eranian@google.com \
--cc=gregkh@linuxfoundation.org \
--cc=jolsa@kernel.org \
--cc=jolsa@redhat.com \
--cc=kan.liang@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=me@kylehuey.com \
--cc=mingo@kernel.org \
--cc=namhyung@kernel.org \
--cc=peterz@infradead.org \
--cc=robert@ocallahan.org \
--cc=stable@vger.kernel.org \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
--cc=vincent.weaver@maine.edu \
--cc=will.deacon@arm.com \
--cc=yao.jin@linux.intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).