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Date: Thu, 8 Oct 2020 14:45:32 +0100
From: André Przywara <andre.przywara@....com>
To: Leo Yan <leo.yan@...aro.org>,
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 04/14] perf arm-spe: Fix packet length handling
On 29/09/2020 14:39, Leo Yan wrote:
> When process address packet and counter packet, if the packet contains
processing
> extended header, it misses to account the extra one byte for header
> length calculation, thus returns the wrong packet length.
>
> To correct the packet length calculation, one possible fixing is simply
> to plus extra 1 for extended header, but will spread some duplicate code
> in the flows for processing address packet and counter packet.
> Alternatively, we can refine the function arm_spe_get_payload() to not
> only support short header and allow it to support extended header, and
> rely on it for the packet length calculation.
>
> So this patch refactors function arm_spe_get_payload() with a new
> argument 'ext_hdr' for support extended header; the packet processing
> flows can invoke this function to unify the packet length calculation.
>
> Signed-off-by: Leo Yan <leo.yan@...aro.org>
That looks alright to me.
Reviewed-by: Andre Przywara <andre.przywara@....com>
Cheers,
Andre
> ---
> .../arm-spe-decoder/arm-spe-pkt-decoder.c | 34 +++++++------------
> 1 file changed, 12 insertions(+), 22 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 5a8696031e16..4f0aeb62e97b 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
> @@ -80,14 +80,15 @@ const char *arm_spe_pkt_name(enum arm_spe_pkt_type type)
> (1 << (((val) & SPE_HEADER_SZ_MASK) >> SPE_HEADER_SZ_SHIFT))
>
> static int arm_spe_get_payload(const unsigned char *buf, size_t len,
> + unsigned char ext_hdr,
> struct arm_spe_pkt *packet)
> {
> - size_t payload_len = PAYLOAD_LEN(buf[0]);
> + size_t payload_len = PAYLOAD_LEN(buf[ext_hdr]);
>
> - if (len < 1 + payload_len)
> + if (len < 1 + ext_hdr + payload_len)
> return ARM_SPE_NEED_MORE_BYTES;
>
> - buf++;
> + buf += 1 + ext_hdr;
>
> switch (payload_len) {
> case 1: packet->payload = *(uint8_t *)buf; break;
> @@ -97,7 +98,7 @@ static int arm_spe_get_payload(const unsigned char *buf, size_t len,
> default: return ARM_SPE_BAD_PACKET;
> }
>
> - return 1 + payload_len;
> + return 1 + ext_hdr + payload_len;
> }
>
> static int arm_spe_get_pad(struct arm_spe_pkt *packet)
> @@ -128,7 +129,7 @@ static int arm_spe_get_timestamp(const unsigned char *buf, size_t len,
> struct arm_spe_pkt *packet)
> {
> packet->type = ARM_SPE_TIMESTAMP;
> - return arm_spe_get_payload(buf, len, packet);
> + return arm_spe_get_payload(buf, len, 0, packet);
> }
>
> static int arm_spe_get_events(const unsigned char *buf, size_t len,
> @@ -143,14 +144,14 @@ static int arm_spe_get_events(const unsigned char *buf, size_t len,
> */
> packet->index = PAYLOAD_LEN(buf[0]);
>
> - return arm_spe_get_payload(buf, len, packet);
> + return arm_spe_get_payload(buf, len, 0, packet);
> }
>
> static int arm_spe_get_data_source(const unsigned char *buf, size_t len,
> struct arm_spe_pkt *packet)
> {
> packet->type = ARM_SPE_DATA_SOURCE;
> - return arm_spe_get_payload(buf, len, packet);
> + return arm_spe_get_payload(buf, len, 0, packet);
> }
>
> static int arm_spe_get_context(const unsigned char *buf, size_t len,
> @@ -158,8 +159,7 @@ static int arm_spe_get_context(const unsigned char *buf, size_t len,
> {
> packet->type = ARM_SPE_CONTEXT;
> packet->index = buf[0] & 0x3;
> -
> - return arm_spe_get_payload(buf, len, packet);
> + return arm_spe_get_payload(buf, len, 0, packet);
> }
>
> static int arm_spe_get_op_type(const unsigned char *buf, size_t len,
> @@ -167,41 +167,31 @@ static int arm_spe_get_op_type(const unsigned char *buf, size_t len,
> {
> packet->type = ARM_SPE_OP_TYPE;
> packet->index = buf[0] & 0x3;
> - return arm_spe_get_payload(buf, len, packet);
> + return arm_spe_get_payload(buf, len, 0, packet);
> }
>
> static int arm_spe_get_counter(const unsigned char *buf, size_t len,
> const unsigned char ext_hdr, struct arm_spe_pkt *packet)
> {
> - if (len < 2)
> - return ARM_SPE_NEED_MORE_BYTES;
> -
> packet->type = ARM_SPE_COUNTER;
> if (ext_hdr)
> packet->index = ((buf[0] & 0x3) << 3) | (buf[1] & 0x7);
> else
> packet->index = buf[0] & 0x7;
>
> - packet->payload = le16_to_cpu(*(uint16_t *)(buf + 1));
> -
> - return 1 + ext_hdr + 2;
> + return arm_spe_get_payload(buf, len, ext_hdr, packet);
> }
>
> static int arm_spe_get_addr(const unsigned char *buf, size_t len,
> const unsigned char ext_hdr, struct arm_spe_pkt *packet)
> {
> - if (len < 8)
> - return ARM_SPE_NEED_MORE_BYTES;
> -
> packet->type = ARM_SPE_ADDRESS;
> if (ext_hdr)
> packet->index = ((buf[0] & 0x3) << 3) | (buf[1] & 0x7);
> else
> packet->index = buf[0] & 0x7;
>
> - memcpy_le64(&packet->payload, buf + 1, 8);
> -
> - return 1 + ext_hdr + 8;
> + return arm_spe_get_payload(buf, len, ext_hdr, packet);
> }
>
> static int arm_spe_do_get_packet(const unsigned char *buf, size_t len,
>
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