linux-kernel - Re: [PATCH 3/4] perf/x86/intel/ds: Handle PEBS overflow for fixed counters

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: <aa546845-cb9d-969b-fa6a-1c8387831edb@linux.intel.com>
Date:   Mon, 23 Jul 2018 13:15:08 -0400
From:   "Liang, Kan" <kan.liang@...ux.intel.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     tglx@...utronix.de, mingo@...hat.com, linux-kernel@...r.kernel.org,
        acme@...nel.org, alexander.shishkin@...ux.intel.com,
        vincent.weaver@...ne.edu, jolsa@...hat.com, ak@...ux.intel.com
Subject: Re: [PATCH 3/4] perf/x86/intel/ds: Handle PEBS overflow for fixed
 counters



On 7/23/2018 12:56 PM, Liang, Kan wrote:
> 
> 
> On 7/23/2018 12:21 PM, Peter Zijlstra wrote:
>> On Mon, Jul 23, 2018 at 04:59:44PM +0200, Peter Zijlstra wrote:
>>> On Thu, Mar 08, 2018 at 06:15:41PM -0800, kan.liang@...ux.intel.com 
>>> wrote:
>>>> diff --git a/arch/x86/events/intel/core.c 
>>>> b/arch/x86/events/intel/core.c
>>>> index ef47a418d819..86149b87cce8 100644
>>>> --- a/arch/x86/events/intel/core.c
>>>> +++ b/arch/x86/events/intel/core.c
>>>> @@ -2280,7 +2280,10 @@ static int intel_pmu_handle_irq(struct 
>>>> pt_regs *regs)
>>>>        * counters from the GLOBAL_STATUS mask and we always process 
>>>> PEBS
>>>>        * events via drain_pebs().
>>>>        */
>>>> -    status &= ~(cpuc->pebs_enabled & PEBS_COUNTER_MASK);
>>>> +    if (x86_pmu.flags & PMU_FL_PEBS_ALL)
>>>> +        status &= ~(cpuc->pebs_enabled & EXTENDED_PEBS_COUNTER_MASK);
>>>> +    else
>>>> +        status &= ~(cpuc->pebs_enabled & PEBS_COUNTER_MASK);
>>>>       /*
>>>>        * PEBS overflow sets bit 62 in the global status register
>>>
>>> Doesn't this re-introduce the problem fixed in commit fd583ad1563be,
>>> where pebs_enabled:32-34 are PEBS Load Latency, instead of fixed
>>> counters?
>>
>> Also, since they 'fixed' that conflict, the PEBS_ALL version could be:
>>
>>     state &= cpuc->pebs_enabled;
>>
>> Right?
> 

Here, we need to clear the bit for PEBS counters.
For PEBS_ALL version, it should be
   status &= ~cpuc->pebs_enabled;


Thanks,
Kan