linux-kernel - Re: [PATCH v6 20/21] perf arm_spe: Decode memory tagging properties

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Message-ID: <20201103065101.GE13232@leoy-ThinkPad-X240s>
Date:   Tue, 3 Nov 2020 14:51:01 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     Dave Martin <Dave.Martin@....com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <Mark.Rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Andre Przywara <Andre.Przywara@....com>,
        James Clark <James.Clark@....com>, Al Grant <Al.Grant@....com>,
        Wei Li <liwei391@...wei.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6 20/21] perf arm_spe: Decode memory tagging properties

On Mon, Nov 02, 2020 at 04:25:36PM +0000, Dave Martin wrote:
> On Fri, Oct 30, 2020 at 02:57:23AM +0000, Leo Yan wrote:
> > From: Andre Przywara <andre.przywara@....com>
> > 
> > When SPE records a physical address, it can additionally tag the event
> > with information from the Memory Tagging architecture extension.
> > 
> > Decode the two additional fields in the SPE event payload.
> > 
> > [leoy: Refined patch to use predefined macros]
> > 
> > Signed-off-by: Andre Przywara <andre.przywara@....com>
> > Signed-off-by: Leo Yan <leo.yan@...aro.org>
> > ---
> >  tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c | 6 +++++-
> >  tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.h | 2 ++
> >  2 files changed, 7 insertions(+), 1 deletion(-)
> > 
> > diff --git a/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c b/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c
> > index 3fca65e9cbbf..9ec3057de86f 100644
> > --- a/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c
> > +++ b/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c
> > @@ -371,6 +371,7 @@ static int arm_spe_pkt_desc_addr(const struct arm_spe_pkt *packet,
> >  				 char *buf, size_t buf_len)
> >  {
> >  	int ns, el, idx = packet->index;
> > +	int ch, pat;
> >  	u64 payload = packet->payload;
> >  	int err = 0;
> >  
> > @@ -388,9 +389,12 @@ static int arm_spe_pkt_desc_addr(const struct arm_spe_pkt *packet,
> >  					    "VA 0x%llx", payload);
> >  	case SPE_ADDR_PKT_HDR_INDEX_DATA_PHYS:
> >  		ns = !!SPE_ADDR_PKT_GET_NS(payload);
> > +		ch = !!SPE_ADDR_PKT_GET_CH(payload);
> > +		pat = SPE_ADDR_PKT_GET_PAT(payload);
> >  		payload = SPE_ADDR_PKT_ADDR_GET_BYTES_0_6(payload);
> >  		return arm_spe_pkt_snprintf(&err, &buf, &buf_len,
> > -					    "PA 0x%llx ns=%d", payload, ns);
> > +					    "PA 0x%llx ns=%d ch=%d, pat=%x",
> 
> Nit: given that this data is all closely related, do we really want the
> extra comma here?

No reason for adding comma.  Will remove it.

> (Note, I am not familiar with how this text is consumed, so if there are
> other reasons why the comma is needed then that's probably fine.)
> 
> > +					    payload, ns, ch, pat);
> >  	default:
> >  		return 0;
> >  	}
> > diff --git a/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.h b/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.h
> > index 7032fc141ad4..1ad14885c2a1 100644
> > --- a/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.h
> > +++ b/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.h
> > @@ -73,6 +73,8 @@ struct arm_spe_pkt {
> >  
> >  #define SPE_ADDR_PKT_GET_NS(v)			(((v) & BIT_ULL(63)) >> 63)
> >  #define SPE_ADDR_PKT_GET_EL(v)			(((v) & GENMASK_ULL(62, 61)) >> 61)
> > +#define SPE_ADDR_PKT_GET_CH(v)			(((v) & BIT_ULL(62)) >> 62)
> > +#define SPE_ADDR_PKT_GET_PAT(v)			(((v) & GENMASK_ULL(59, 56)) >> 56)
> 
> These seem to match the spec.
> 
> With or without addressing the nit above:
> 
> Reviewed-by: Dave Martin <Dave.Martin@....com>

Thanks for reviewing.

> [...]
> 
> Cheers
> ---Dave