linux-kernel - Re: [PATCH 0/3] perf/core, x86: unify perfctr bitmasks

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Date:	Thu, 01 Apr 2010 10:14:08 +0800
From:	Lin Ming <ming.m.lin@...el.com>
To:	Cyrill Gorcunov <gorcunov@...il.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Robert Richter <robert.richter@....com>,
	Stephane Eranian <eranian@...gle.com>,
	Ingo Molnar <mingo@...e.hu>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/3] perf/core, x86: unify perfctr bitmasks

On Thu, 2010-04-01 at 01:05 +0800, Cyrill Gorcunov wrote:
> On Wed, Mar 31, 2010 at 08:26:47PM +0400, Cyrill Gorcunov wrote:
> > On Wed, Mar 31, 2010 at 08:15:23PM +0400, Cyrill Gorcunov wrote:
> > > On Tue, Mar 30, 2010 at 09:04:00PM +0200, Peter Zijlstra wrote:
> > > > On Tue, 2010-03-30 at 22:29 +0400, Cyrill Gorcunov wrote:
> > > [...]
> > > > > 
> > [...]
> > > +static inline bool p4_is_odd_cpl(u32 escr)
> > > +{
> > > +	unsigned int t0 = (escr & P4_ESCR_T0_ANY) << 0;
> > > +	unsigned int t1 = (escr & P4_ESCR_T1_ANY) << 2;
> > > +
> > > +	if ((t0 ^ t1) != t0)
> > > +		return true;
> > 
> > /me in shame: This is bogus, Peter don't take it yet.
> >
> 
> Updated
>  
> 	-- Cyrill
> ---
> x86, perf: P4 PMU -- check for permission granted on ANY event v2
> 
> In case if a caller (user) asked us to count events with
> some weird mask we should check if this priviledge has been
> granted since this could be a mix of bitmasks we not like
> which but allow if caller insist.
> 
> By ANY event term the combination of USR/OS bits in ESCR
> register is assumed.

I'll test this patch.
Does it need to be applied on top of Robert's patch?

Lin Ming

> 
> CC: Peter Zijlstra <peterz@...radead.org>
> Signed-off-by: Cyrill Gorcunov <gorcunov@...nvz.org>
> ---
>  arch/x86/include/asm/perf_event_p4.h |   17 +++++++++++++++++
>  arch/x86/kernel/cpu/perf_event_p4.c  |   24 +++++++++++++++++++++---
>  2 files changed, 38 insertions(+), 3 deletions(-)
> 
> Index: linux-2.6.git/arch/x86/include/asm/perf_event_p4.h
> =====================================================================
> --- linux-2.6.git.orig/arch/x86/include/asm/perf_event_p4.h
> +++ linux-2.6.git/arch/x86/include/asm/perf_event_p4.h
> @@ -33,6 +33,9 @@
>  #define P4_ESCR_T1_OS		0x00000002U
>  #define P4_ESCR_T1_USR		0x00000001U
>  
> +#define P4_ESCR_T0_ANY		(P4_ESCR_T0_OS | P4_ESCR_T0_USR)
> +#define P4_ESCR_T1_ANY		(P4_ESCR_T1_OS | P4_ESCR_T1_USR)
> +
>  #define P4_ESCR_EVENT(v)	((v) << P4_ESCR_EVENT_SHIFT)
>  #define P4_ESCR_EMASK(v)	((v) << P4_ESCR_EVENTMASK_SHIFT)
>  #define P4_ESCR_TAG(v)		((v) << P4_ESCR_TAG_SHIFT)
> @@ -134,6 +137,20 @@
>  #define P4_CONFIG_HT_SHIFT		63
>  #define P4_CONFIG_HT			(1ULL << P4_CONFIG_HT_SHIFT)
>  
> +/*
> + * typically we set USR or/and OS bits for one of the
> + * threads only at once, any other option is treated
> + * as "any"
> + */
> +static inline bool p4_is_any_cpl(u32 escr)
> +{
> +	if ((escr & P4_ESCR_T0_ANY) &&
> +	    (escr & P4_ESCR_T1_ANY))
> +		return true;
> +
> +	return false;
> +}
> +
>  static inline bool p4_is_event_cascaded(u64 config)
>  {
>  	u32 cccr = p4_config_unpack_cccr(config);
> Index: linux-2.6.git/arch/x86/kernel/cpu/perf_event_p4.c
> =====================================================================
> --- linux-2.6.git.orig/arch/x86/kernel/cpu/perf_event_p4.c
> +++ linux-2.6.git/arch/x86/kernel/cpu/perf_event_p4.c
> @@ -443,13 +443,18 @@ static int p4_hw_config(struct perf_even
>  		return 0;
>  
>  	/*
> +	 * a caller may ask for something definitely weird and
> +	 * screwed, sigh...
> +	 */
> +	escr = p4_config_unpack_escr(event->attr.config);
> +	if (p4_is_any_cpl(escr) && perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN))
> +		return -EACCES;
> +
> +	/*
>  	 * We don't control raw events so it's up to the caller
>  	 * to pass sane values (and we don't count the thread number
>  	 * on HT machine but allow HT-compatible specifics to be
>  	 * passed on)
> -	 *
> -	 * XXX: HT wide things should check perf_paranoid_cpu() &&
> -	 *      CAP_SYS_ADMIN
>  	 */
>  	event->hw.config |= event->attr.config &
>  		(p4_config_pack_escr(P4_ESCR_MASK_HT) |
> @@ -630,6 +635,19 @@ static void p4_pmu_swap_config_ts(struct
>  	escr = p4_config_unpack_escr(hwc->config);
>  	cccr = p4_config_unpack_cccr(hwc->config);
>  
> +	/*
> +	 * for non-standart configs we don't clobber cpl
> +	 * related bits so it's preferred the caller don't
> +	 * use this mode
> +	 */
> +	if (unlikely(p4_is_any_cpl(escr))) {
> +		if (p4_ht_thread(cpu))
> +			hwc->config |= P4_CONFIG_HT;
> +		else
> +			hwc->config &= ~P4_CONFIG_HT;
> +		return;
> +	}
> +
>  	if (p4_ht_thread(cpu)) {
>  		cccr &= ~P4_CCCR_OVF_PMI_T0;
>  		cccr |= P4_CCCR_OVF_PMI_T1;

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