Re: [PATCH 08/10] perf hisi-ptt: Add parsing of supported message types

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The decoder uses C bitfields (`dw0_4dw` and the newly added `dw0_8dw`) to parse hardware headers from a host-endian integer, which breaks cross-platform perf trace analysis on big-endian architectures.
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commit e6402a0d73ba805c4892540373d8a6a210da4d39
Author: Sizhe Liu <liusizhe5@huawei.com>

perf hisi-ptt: Add parsing of supported message types

This commit adds logic to parse TLP message types from Header DW0 Format and
Type fields for 4DW and 8DW packets. It stores the parsed message type in the
packet buffer to select the correct field layout for subsequent decoding steps.

> diff --git a/tools/perf/util/hisi-ptt-decoder/hisi-ptt-pkt-decoder.c b/tools/perf/util/hisi-ptt-decoder/hisi-ptt-pkt-decoder.c
> index 9ec84d398cc1b..59ab8ec3a03da 100644
> --- a/tools/perf/util/hisi-ptt-decoder/hisi-ptt-pkt-decoder.c
> +++ b/tools/perf/util/hisi-ptt-decoder/hisi-ptt-pkt-decoder.c
[ ... ]
> @@ -90,9 +121,41 @@ union hisi_ptt_field_data {
>  		uint32_t type : 5;
>  		uint32_t format : 2;
>  	} dw0_4dw;
> +	/* Header DW0 for 8DW format */
> +	struct {
> +		uint32_t others : 24;
> +		uint32_t type : 5;
> +		uint32_t format : 3;
> +	} dw0_8dw;

[Severity: Medium]
Will this bitfield layout break cross-platform perf trace analysis on
big-endian architectures?

The hardware payload is loaded via le32_to_cpu(), which correctly guarantees a
host-endian integer, but mapping C bitfields onto that integer relies on
implementation-defined behavior. On big-endian hosts, GCC packs bitfields
starting from the most significant bit, so accessing dw.dw0_8dw.format or
dw.dw0_8dw.type will extract the wrong bits.

Could these fields be extracted using standard bitwise shifts and masks
instead of relying on bitfield layout?

>  	uint32_t value;
>  };
>  
> +static int hisi_ptt_parse_pkt_msg_type(union hisi_ptt_field_data dw,
> +				       enum hisi_ptt_pkt_type pkt_type)
> +{
> +	uint32_t format, type;
> +
> +	format = (pkt_type == HISI_PTT_4DW_PKT) ? dw.dw0_4dw.format :
> +						  dw.dw0_8dw.format;
> +	type = (pkt_type == HISI_PTT_4DW_PKT) ? dw.dw0_4dw.type :
> +						dw.dw0_8dw.type;
[ ... ]

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Sashiko AI review · https://sashiko.dev/#/patchset/20260604075005.2219785-1-liusizhe5@huawei.com?part=8