linux-kernel - RE: [PATCH V5] perf/x86: add sysfs entry to freeze counter on SMI

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Date:   Wed, 10 May 2017 15:56:51 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     "Liang, Kan" <kan.liang@...el.com>
cc:     "'peterz@...radead.org'" <peterz@...radead.org>,
        "'mingo@...hat.com'" <mingo@...hat.com>,
        "'linux-kernel@...r.kernel.org'" <linux-kernel@...r.kernel.org>,
        "'bp@...en8.de'" <bp@...en8.de>,
        "'acme@...nel.org'" <acme@...nel.org>,
        "'eranian@...gle.com'" <eranian@...gle.com>,
        "'jolsa@...nel.org'" <jolsa@...nel.org>,
        "'ak@...ux.intel.com'" <ak@...ux.intel.com>
Subject: RE: [PATCH V5] perf/x86: add sysfs entry to freeze counter on SMI

On Mon, 8 May 2017, Liang, Kan wrote:

> Hi tglx,
> 
> Are you OK with patch?
> Could I get your "acked-by"?

No.

> > > +static void flip_smm_bit(void *data)
> > > +{
> > > +	bool set = *(int *)data;

data points to an unsigned long. So while this works on LE machines this is
still crap.

> > > +	if (set) {
> > > +		msr_set_bit(MSR_IA32_DEBUGCTLMSR,
> > > +			    DEBUGCTLMSR_FREEZE_IN_SMM_BIT);
> > > +	} else {
> > > +		msr_clear_bit(MSR_IA32_DEBUGCTLMSR,
> > > +			      DEBUGCTLMSR_FREEZE_IN_SMM_BIT);
> > > +	}

I probably forgot, but why do we need an open coded version of __flip_bit()
instead of reusing that?

Thanks,

	tglx