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From: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
To: peterz@infradead.org, jolsa@redhat.com, mpe@ellerman.id.au,
	maddy@linux.vnet.ibm.com
Cc: acme@kernel.org, linux-kernel@vger.kernel.org,
	linuxppc-dev@lists.ozlabs.org,
	Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Subject: Re: [PATCH 2/2] powerpc/perf: Fix mmcra corruption by bhrb_filter
Date: Sat, 11 May 2019 08:17:21 +0530	[thread overview]
Message-ID: <4f3cab49-7ee5-cb01-65d9-0dce79db581d@linux.ibm.com> (raw)
In-Reply-To: <20190511024217.4013-2-ravi.bangoria@linux.ibm.com>



On 5/11/19 8:12 AM, Ravi Bangoria wrote:
> Consider a scenario where user creates two events:
> 
>   1st event:
>     attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
>     attr.branch_sample_type = PERF_SAMPLE_BRANCH_ANY;
>     fd = perf_event_open(attr, 0, 1, -1, 0);
> 
>   This sets cpuhw->bhrb_filter to 0 and returns valid fd.
> 
>   2nd event:
>     attr.sample_type |= PERF_SAMPLE_BRANCH_STACK;
>     attr.branch_sample_type = PERF_SAMPLE_BRANCH_CALL;
>     fd = perf_event_open(attr, 0, 1, -1, 0);
> 
>   It overrides cpuhw->bhrb_filter to -1 and returns with error.
> 
> Now if power_pmu_enable() gets called by any path other than
> power_pmu_add(), ppmu->config_bhrb(-1) will set mmcra to -1.
> 
> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>

Fixes: 3925f46bb590 ("powerpc/perf: Enable branch stack sampling framework")


  reply	other threads:[~2019-05-11  2:47 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-11  2:42 [PATCH 1/2] perf ioctl: Add check for the sample_period value Ravi Bangoria
2019-05-11  2:42 ` [PATCH 2/2] powerpc/perf: Fix mmcra corruption by bhrb_filter Ravi Bangoria
2019-05-11  2:47   ` Ravi Bangoria [this message]
2019-05-22  5:01   ` Madhavan Srinivasan
2019-05-25  0:54   ` Michael Ellerman
2019-05-13  7:42 ` [PATCH 1/2] perf ioctl: Add check for the sample_period value Peter Zijlstra
2019-05-13  8:56   ` Peter Zijlstra
2019-05-13 10:07     ` Ravi Bangoria
2019-05-28  9:50       ` Michael Ellerman
2019-06-04  4:29         ` [PATCH v2] " Ravi Bangoria
2019-06-17  8:38           ` Ravi Bangoria
2019-06-18 12:28             ` Michael Ellerman
2019-06-25  8:19           ` [tip:perf/urgent] perf/ioctl: " tip-bot for Ravi Bangoria

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