linux-kernel - Re: [PATCH] perf arm-spe: Add raw decoding for SPEv1.2 previous branch address

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Date:   Wed, 1 Feb 2023 22:15:09 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Leo Yan <leo.yan@...aro.org>
Cc:     Rob Herring <robh@...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@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        James Clark <james.clark@....com>,
        Will Deacon <will@...nel.org>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf arm-spe: Add raw decoding for SPEv1.2 previous
 branch address

Em Mon, Jan 30, 2023 at 10:09:46AM +0800, Leo Yan escreveu:
> On Fri, Jan 27, 2023 at 02:59:51PM -0600, Rob Herring wrote:
> > Arm SPEv1.2 adds a new optional address packet type: previous branch
> > target. The recorded address is the target virtual address of the most
> > recently taken branch in program order.
> > 
> > Add support for decoding the address packet in raw dumps.
> > 
> > Signed-off-by: Rob Herring <robh@...nel.org>
> > ---
> >  tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c | 4 +++-
> >  tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.h | 1 +
> >  2 files changed, 4 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 2f311189c6e8..e92e1a7c8a8e 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
> > @@ -422,16 +422,18 @@ static int arm_spe_pkt_desc_addr(const struct arm_spe_pkt *packet,
> >  	int ch, pat;
> >  	u64 payload = packet->payload;
> >  	int err = 0;
> > +	static const char *idx_name[] = {"PC", "TGT", "VA", "PA", "LBR" };
> 
> I know you use the "LBR" which is a naming convention from X86 arch,
> Armv8 ARM defines the name "PBT", so "PBT" would be easier for us to
> match code with architecture specification.
> 
> "LBR" is also fine for me, it's up to you if you want to update for
> this:

Waiting for a response to this.

- Arnaldo
 
> Reviewed-by: Leo Yan <leo.yan@...aro.org>
> 
> 
> >  	switch (idx) {
> >  	case SPE_ADDR_PKT_HDR_INDEX_INS:
> >  	case SPE_ADDR_PKT_HDR_INDEX_BRANCH:
> > +	case SPE_ADDR_PKT_HDR_INDEX_PREV_BRANCH:
> >  		ns = !!SPE_ADDR_PKT_GET_NS(payload);
> >  		el = SPE_ADDR_PKT_GET_EL(payload);
> >  		payload = SPE_ADDR_PKT_ADDR_GET_BYTES_0_6(payload);
> >  		arm_spe_pkt_out_string(&err, &buf, &buf_len,
> >  				"%s 0x%llx el%d ns=%d",
> > -				(idx == 1) ? "TGT" : "PC", payload, el, ns);
> > +				idx_name[idx], payload, el, ns);
> >  		break;
> >  	case SPE_ADDR_PKT_HDR_INDEX_DATA_VIRT:
> >  		arm_spe_pkt_out_string(&err, &buf, &buf_len,
> > 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 9b970e7bf1e2..f75ed3a8a050 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
> > @@ -65,6 +65,7 @@ struct arm_spe_pkt {
> >  #define SPE_ADDR_PKT_HDR_INDEX_BRANCH		0x1
> >  #define SPE_ADDR_PKT_HDR_INDEX_DATA_VIRT	0x2
> >  #define SPE_ADDR_PKT_HDR_INDEX_DATA_PHYS	0x3
> > +#define SPE_ADDR_PKT_HDR_INDEX_PREV_BRANCH	0x4
> >  
> >  /* Address packet payload */
> >  #define SPE_ADDR_PKT_ADDR_BYTE7_SHIFT		56
> > -- 
> > 2.39.0
> > 

-- 

- Arnaldo