linux-kernel - Re: [PATCH V2 0/2] perf/x86/intel/pt: Add support for event tracing and TNT disabling

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <f2c2389e-db62-c307-b5d7-6a8d9df70b7e@intel.com>
Date:   Tue, 15 Feb 2022 17:40:45 +0200
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...hat.com>, linux-kernel@...r.kernel.org,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        H Peter Anvin <hpa@...or.com>
Subject: Re: [PATCH V2 0/2] perf/x86/intel/pt: Add support for event tracing
 and TNT disabling

On 15/02/2022 17:35, Peter Zijlstra wrote:
> On Wed, Jan 26, 2022 at 12:48:13PM +0200, Adrian Hunter wrote:
>> Hi
>>
>> As of Intel SDM (https://www.intel.com/sdm) version 076, there are 2 new
>> Intel PT features called Event Trace and TNT-Disable.
>>
>> Event Trace exposes details about asynchronous events such as interrupts
>> and VM-Entry/Exit.
>>
>> TNT-Disable disables TNT packets to reduce the tracing overhead, but with
>> the result that exact control flow information is lost.
> 
> What's a TNT?

The TNT packet indicates whether conditional branches were taken
or not taken.