From: Ingo Molnar <mingo@kernel.org>
To: Andi Kleen <ak@linux.intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
linux-kernel@vger.kernel.org, eranian@google.com,
Arnaldo Carvalho de Melo <acme@infradead.org>
Subject: Re: [PATCH 2/3] perf, x86, lbr: Fix LBR filter
Date: Sat, 4 May 2013 08:34:20 +0200 [thread overview]
Message-ID: <20130504063420.GA14614@gmail.com> (raw)
In-Reply-To: <20130503143411.GO19487@tassilo.jf.intel.com>
* Andi Kleen <ak@linux.intel.com> wrote:
> > + } else {
> > + /*
> > + * The LBR logs any address in the IP, even if the IP just
> > + * faulted. This means userspace can control the from address.
> > + * Ensure we don't blindy read any address by validating it is
> > + * a known text address.
> > + */
> > + if (kernel_text_address(from))
>
> Sorry doing it this way is just incredible expensive and dumb.
If anyone using this feature notices the __module_address() overhead then
a 'module addresses RCU rbtree' could be added, which should solve the
overhead impact.
In any case Peter's patch fixes the bug without regressing the feature as
it is implemented today. Do you have a better solution that does not break
the ABI? The solution you proposed before regresses existing
functionality.
Thanks,
Ingo
next prev parent reply other threads:[~2013-05-04 6:34 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-03 12:11 [PATCH 0/3] Various perf patches Peter Zijlstra
2013-05-03 12:11 ` [PATCH 1/3] perf, x86: Blacklist all MEM_*_RETIRED events for IVB Peter Zijlstra
2013-05-03 14:35 ` Andi Kleen
2013-05-03 17:00 ` Peter Zijlstra
2013-05-15 14:20 ` Stephane Eranian
2013-05-15 16:51 ` Peter Zijlstra
2013-05-16 15:42 ` Stephane Eranian
2013-05-16 16:07 ` Andi Kleen
2013-05-16 16:26 ` Stephane Eranian
2013-05-04 8:20 ` [tip:perf/urgent] perf/x86: Blacklist all MEM_*_RETIRED events for Ivy Bridge tip-bot for Peter Zijlstra
2013-05-03 12:11 ` [PATCH 2/3] perf, x86, lbr: Fix LBR filter Peter Zijlstra
2013-05-03 14:34 ` Andi Kleen
2013-05-04 6:34 ` Ingo Molnar [this message]
2013-05-04 8:21 ` [tip:perf/urgent] perf/x86/intel/lbr: " tip-bot for Peter Zijlstra
2013-05-03 12:11 ` [PATCH 3/3] perf, x86, lbr: Demand proper privileges for PERF_SAMPLE_BRANCH_KERNEL Peter Zijlstra
2013-05-03 14:41 ` Andi Kleen
2013-05-04 8:22 ` [tip:perf/urgent] perf/x86/intel/lbr: " tip-bot for Peter Zijlstra
2013-05-04 11:19 ` Borislav Petkov
2013-05-05 9:05 ` Ingo Molnar
2013-05-06 8:07 ` Peter Zijlstra
2013-05-06 9:42 ` Ingo Molnar
2013-05-15 13:37 ` [PATCH 3/3] perf, x86, lbr: " Stephane Eranian
2013-05-15 14:30 ` Peter Zijlstra
2013-05-16 9:09 ` Peter Zijlstra
2013-05-16 9:17 ` Peter Zijlstra
2013-05-16 10:09 ` Michael Neuling
2013-05-16 10:09 ` Michael Neuling
2013-05-16 10:15 ` Michael Neuling
2013-05-16 10:15 ` Michael Neuling
2013-05-16 11:16 ` Peter Zijlstra
2013-05-16 11:16 ` Peter Zijlstra
2013-05-16 15:36 ` Stephane Eranian
2013-05-16 15:36 ` Stephane Eranian
2013-05-17 11:12 ` Peter Zijlstra
2013-05-17 11:12 ` Peter Zijlstra
2013-05-17 11:32 ` Michael Neuling
2013-05-17 11:32 ` Michael Neuling
2013-05-17 11:39 ` Peter Zijlstra
2013-05-17 11:39 ` Peter Zijlstra
2013-05-17 21:39 ` Stephane Eranian
2013-05-17 21:39 ` Stephane Eranian
2013-05-17 22:14 ` Michael Neuling
2013-05-17 22:14 ` Michael Neuling
2013-05-17 22:59 ` Stephane Eranian
2013-05-17 22:59 ` Stephane Eranian
2013-05-21 5:41 ` Michael Neuling
2013-05-21 5:41 ` Michael Neuling
2013-05-21 8:50 ` Peter Zijlstra
2013-05-21 8:50 ` Peter Zijlstra
2013-05-21 13:46 ` Stephane Eranian
2013-05-21 13:46 ` Stephane Eranian
2013-05-21 13:55 ` Stephane Eranian
2013-05-21 13:55 ` Stephane Eranian
2013-05-22 6:43 ` Anshuman Khandual
2013-05-22 12:23 ` Stephane Eranian
2013-05-22 14:51 ` Anshuman Khandual
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=20130504063420.GA14614@gmail.com \
--to=mingo@kernel.org \
--cc=a.p.zijlstra@chello.nl \
--cc=acme@infradead.org \
--cc=ak@linux.intel.com \
--cc=eranian@google.com \
--cc=linux-kernel@vger.kernel.org \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.