From: Alexey Budankov <alexey.budankov@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
Andi Kleen <ak@linux.intel.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
linux-perf-users@vger.kernel.org,
Andy Lutomirski <luto@kernel.org>
Subject: Re: [PATCH v2]: perf/x86: store user space frame-pointer value on a sample
Date: Thu, 10 May 2018 13:29:28 +0300 [thread overview]
Message-ID: <6be7739b-8c6c-bbd8-6866-a26d8d25266d@linux.intel.com> (raw)
In-Reply-To: <20180510101406.GA12217@hirez.programming.kicks-ass.net>
Hi,
On 10.05.2018 13:14, Peter Zijlstra wrote:
> On Thu, May 10, 2018 at 12:42:38PM +0300, Alexey Budankov wrote:
>>> The Changelog needs to state that user_regs->bp is in fact valid and
>>
>> That actually was tested on binaries compiled without and with BP exposed
>> and in the latter case proved the value of that change.
>
> Mostly works is not the same as 'always initialized', if there are entry
> paths that do not store that register, then using the value might leak
> values from the kernel stack, which would be bad.
Yep, absolutely agree. Extra care needs to be taken here.
>
> But like said, I think much of the kernel entry code was sanitized with
> the PTI effort and I suspect things are in fact fine now, but lets wait
> for Andy to confirm.
>
Thanks,
Alexey
next prev parent reply other threads:[~2018-05-10 10:29 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-08 15:21 [PATCH v2]: perf/x86: store user space frame-pointer value on a sample Alexey Budankov
2018-05-09 14:54 ` Peter Zijlstra
2018-05-10 9:42 ` Alexey Budankov
2018-05-10 10:14 ` Peter Zijlstra
2018-05-10 10:29 ` Alexey Budankov [this message]
2018-05-21 12:44 ` Alexey Budankov
2018-05-21 14:14 ` Andy Lutomirski
2018-05-21 16:51 ` Alexey Budankov
2018-05-21 17:23 ` Andy Lutomirski
2018-05-21 18:11 ` Alexey Budankov
2018-05-23 10:06 ` Alexey Budankov
2018-05-23 13:09 ` Peter Zijlstra
2018-05-24 14:37 ` Alexey Budankov
2018-05-24 14:52 ` Andy Lutomirski
2018-05-15 8:08 ` Alexey Budankov
2018-05-15 16:30 ` Andy Lutomirski
2018-05-16 8:42 ` Alexey Budankov
2018-05-18 7:39 ` Alexey Budankov
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