From: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] powerpc/perf: use MSR to report privilege level on P9 DD1
Date: Tue, 17 Jan 2017 11:48:26 +0530 [thread overview]
Message-ID: <556f4715-254c-7e3d-333c-518b1f7e96de@linux.vnet.ibm.com> (raw)
In-Reply-To: <87fukib5mg.fsf@concordia.ellerman.id.au>
On Tuesday 17 January 2017 11:16 AM, Michael Ellerman wrote:
> Madhavan Srinivasan <maddy@linux.vnet.ibm.com> writes:
>
>> "use_siar" variable is primarily used for deciding the sampled address
>> and the privilege level to be reported for a sample. perf_read_regs()
>> function updates the "use_siar" and "regs->result" based on the pmu
>> flags along with other checks. To force the use of MSR to report the
>> privilege level and to use "regs->nip" to report the instruction pointer,
>> set "PPMU_NO_CONT_SAMPLING" flag and remove "PPMU_HAS_SIER" from the
>> ppmu->flags.
> This still won't work for marked events AFAICS:
nice catch. My bad. Did not try with the marked events when testing this
patch.
>
> if (TRAP(regs) != 0xf00)
> use_siar = 0;
> else if (marked)
> use_siar = 1;
> else if ((ppmu->flags & PPMU_NO_CONT_SAMPLING))
> use_siar = 0;
> else if (!(ppmu->flags & PPMU_NO_SIPR) && regs_sipr(regs))
> use_siar = 0;
> else
> use_siar = 1;
>
> So perhaps we just want a USE_SIAR flag?
OK, Will add a new flag. How about "PPMU_DISBALE_USE_SIAR"?
> And I don't see how HAS_SIER is related? Or is SIER broken too?
We dont see proper values in SIER for some samples and we use
SIER (regs_sipr) to update the misc_flag.
Will fix the commit message.
Maddy
> cheers
>
prev parent reply other threads:[~2017-01-17 6:18 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-03 9:13 [PATCH] powerpc/perf: use MSR to report privilege level on P9 DD1 Madhavan Srinivasan
2017-01-17 5:46 ` Michael Ellerman
2017-01-17 6:18 ` Madhavan Srinivasan [this message]
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