linux-kernel - RE: [PATCH v2] Added perf functionality to mmdc driver

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: <DB5PR04MB14309188D99C35809DDA377B9F130@DB5PR04MB1430.eurprd04.prod.outlook.com>
Date:	Tue, 16 Aug 2016 14:40:43 +0000
From:	Zhengyu Shen <zhengyu.shen@....com>
To:	Mark Rutland <mark.rutland@....com>
CC:	"shawnguo@...nel.org" <shawnguo@...nel.org>,
	"peterz@...radead.org" <peterz@...radead.org>,
	Frank Li <frank.li@....com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"acme@...nel.org" <acme@...nel.org>,
	"alexander.shishkin@...ux.intel.com" 
	<alexander.shishkin@...ux.intel.com>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"lznuaa@...il.com" <lznuaa@...il.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: RE: [PATCH v2] Added perf functionality to mmdc driver

> > 	Added cpumask and migration handling support to driver
> > 	Validated event during event_init
> > 	Added code to properly stop counters
> > 	Used perf_invalid_context instead of perf_sw_context
> > 	Added hrtimer to poll for overflow
> > 	Added better description
> > 	Added support for multiple mmdcs
> 
> As I commented on v1 w.r.t. the above, I would appreciate being Cc'd on
> future versions of this patch.

Sorry about that, I'll be sure to CC you in the future. 

> > +static void mmdc_event_start(struct perf_event *event, int flags) {
> > +	struct mmdc_pmu *pmu_mmdc = to_mmdc_pmu(event->pmu);
> > +	void __iomem *mmdc_base, *reg;
> > +
> > +	local64_set(&event->count, 0);
> > +	mmdc_base = pmu_mmdc->mmdc_base;
> > +	reg = mmdc_base + MMDC_MADPCR0;
> > +	hrtimer_start(&pmu_mmdc->hrtimer, mmdc_timer_period(),
> > +			HRTIMER_MODE_REL_PINNED);
> 
> Why is a hrtimer necessary? Is this just copy-pasted from CCN, or do you
> have similar HW issues?
> 
> Is there no overflow interrupt?

When overflow occurs, a register bit is set to one. There is no overflow
interrupt which is why the timer is needed. 

Thanks a lot for the feedback!