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Message-ID: <20201021035212.GC7226@leoy-ThinkPad-X240s>
Date: Wed, 21 Oct 2020 11:52:12 +0800
From: Leo Yan <leo.yan@...aro.org>
To: André Przywara <andre.przywara@....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>,
Wei Li <liwei391@...wei.com>,
James Clark <james.clark@....com>,
Dave Martin <Dave.Martin@....com>,
linux-kernel@...r.kernel.org, Al Grant <Al.Grant@....com>
Subject: Re: [PATCH v2 09/14] perf arm-spe: Refactor counter packet handling
On Tue, Oct 20, 2020 at 10:53:47PM +0100, André Przywara wrote:
> On 29/09/2020 14:39, Leo Yan wrote:
>
> Hi,
>
> > This patch defines macros for counter packet header, and uses macro to
> > replace hard code values for packet parsing.
> >
> > Signed-off-by: Leo Yan <leo.yan@...aro.org>
> > ---
> > .../util/arm-spe-decoder/arm-spe-pkt-decoder.c | 17 ++++++++++-------
> > .../util/arm-spe-decoder/arm-spe-pkt-decoder.h | 9 +++++++++
> > 2 files changed, 19 insertions(+), 7 deletions(-)
> >
> > 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 00a2cd1af422..ed0f4c74dfc5 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
> > @@ -150,10 +150,13 @@ static int arm_spe_get_counter(const unsigned char *buf, size_t len,
> > const unsigned char ext_hdr, struct arm_spe_pkt *packet)
> > {
> > packet->type = ARM_SPE_COUNTER;
> > - if (ext_hdr)
> > - packet->index = ((buf[0] & 0x3) << 3) | (buf[1] & 0x7);
> > - else
> > - packet->index = buf[0] & 0x7;
> > + if (ext_hdr) {
> > + packet->index = (buf[1] & SPE_CNT_PKT_HDR_INDEX_MASK);
> > + packet->index |= ((buf[0] & SPE_CNT_PKT_HDR_EXT_INDEX_MASK)
> > + << SPE_CNT_PKT_HDR_EXT_INDEX_SHIFT);
> > + } else {
> > + packet->index = buf[0] & SPE_CNT_PKT_HDR_INDEX_MASK;
>
> That looks suspiciously similar to the extended header in the address
> packet. Can you use the same name for that?
Checked for counter packet and address packet, they are using the same
format for index. Will use the same name.
> And, similar to the address packet, what about:
> packet->index |= SPE_PKT_EXT_HEADER_INDEX(buf[0]);
Will do.
> (merging the mask and the shift in the macro definition)
>
> > + }
> >
> > return arm_spe_get_payload(buf, len, ext_hdr, packet);
> > }
> > @@ -431,17 +434,17 @@ int arm_spe_pkt_desc(const struct arm_spe_pkt *packet, char *buf,
> > return ret;
> >
> > switch (idx) {
> > - case 0:
> > + case SPE_CNT_PKT_HDR_INDEX_TOTAL_LAT:
> > ret = arm_spe_pkt_snprintf(&buf, &blen, "TOT");
> > if (ret < 0)
> > return ret;
> > break;
> > - case 1:
> > + case SPE_CNT_PKT_HDR_INDEX_ISSUE_LAT:
> > ret = arm_spe_pkt_snprintf(&buf, &blen, "ISSUE");
> > if (ret < 0)
> > return ret;
> > break;
> > - case 2:
> > + case SPE_CNT_PKT_HDR_INDEX_TRANS_LAT:
> > ret = arm_spe_pkt_snprintf(&buf, &blen, "XLAT");
> > if (ret < 0)
> > return ret;
> > 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 62db4ff91832..18667a63f5ba 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
> > @@ -89,6 +89,15 @@ struct arm_spe_pkt {
> > /* Context packet header */
> > #define SPE_CTX_PKT_HDR_INDEX_MASK GENMASK_ULL(1, 0)
> >
> > +/* Counter packet header */
> > +#define SPE_CNT_PKT_HDR_INDEX_MASK GENMASK_ULL(2, 0)
> > +#define SPE_CNT_PKT_HDR_INDEX_TOTAL_LAT (0x0)
> > +#define SPE_CNT_PKT_HDR_INDEX_ISSUE_LAT (0x1)
> > +#define SPE_CNT_PKT_HDR_INDEX_TRANS_LAT (0x2)
>
> I think the Linux kernel coding style does not mention parentheses just
> around numbers, so just 0x2 would suffice, for instance.
> See section 12) in Documentation/process/coding-style.rst
Yeah, it gives example as "#define CONSTANT 0x4000"; will follow the
coding style.
Thanks for suggestions!
Leo
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