[PATCH 2/4] perf arm_spe: Turn event name mappings into an array
Ian Rogers
irogers at google.com
Thu Apr 2 08:30:14 PDT 2026
On Wed, Apr 1, 2026 at 7:26 AM James Clark <james.clark at linaro.org> wrote:
>
> This is so we can have a single function that prints events and can be
> used with multiple mappings from different CPUs. Remove any bit that was
> printed so that later we can print out the remaining unknown impdef
> bits.
>
> No functional changes intended.
>
> Signed-off-by: James Clark <james.clark at linaro.org>
> ---
> .../util/arm-spe-decoder/arm-spe-pkt-decoder.c | 88 +++++++++++-----------
> 1 file changed, 43 insertions(+), 45 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 5769ba2f4140..c880b0dec3a1 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
> @@ -276,6 +276,48 @@ static int arm_spe_pkt_out_string(int *err, char **buf_p, size_t *blen,
> return ret;
> }
>
> +struct ev_string {
> + u8 event;
> + const char *desc;
> +};
> +
> +static const struct ev_string common_ev_strings[] = {
> + { .event = EV_EXCEPTION_GEN, .desc = "EXCEPTION-GEN" },
> + { .event = EV_RETIRED, .desc = "RETIRED" },
> + { .event = EV_L1D_ACCESS, .desc = "L1D-ACCESS" },
> + { .event = EV_L1D_REFILL, .desc = "L1D-REFILL" },
> + { .event = EV_TLB_ACCESS, .desc = "TLB-ACCESS" },
> + { .event = EV_TLB_WALK, .desc = "TLB-REFILL" },
> + { .event = EV_NOT_TAKEN, .desc = "NOT-TAKEN" },
> + { .event = EV_MISPRED, .desc = "MISPRED" },
> + { .event = EV_LLC_ACCESS, .desc = "LLC-ACCESS" },
> + { .event = EV_LLC_MISS, .desc = "LLC-REFILL" },
> + { .event = EV_REMOTE_ACCESS, .desc = "REMOTE-ACCESS" },
> + { .event = EV_ALIGNMENT, .desc = "ALIGNMENT" },
> + { .event = EV_TRANSACTIONAL, .desc = "TXN" },
> + { .event = EV_PARTIAL_PREDICATE, .desc = "SVE-PARTIAL-PRED" },
> + { .event = EV_EMPTY_PREDICATE, .desc = "SVE-EMPTY-PRED" },
> + { .event = EV_L2D_ACCESS, .desc = "L2D-ACCESS" },
> + { .event = EV_L2D_MISS, .desc = "L2D-MISS" },
> + { .event = EV_CACHE_DATA_MODIFIED, .desc = "HITM" },
> + { .event = EV_RECENTLY_FETCHED, .desc = "LFB" },
> + { .event = EV_DATA_SNOOPED, .desc = "SNOOPED" },
> + { .event = EV_STREAMING_SVE_MODE, .desc = "STREAMING-SVE" },
> + { .event = EV_SMCU, .desc = "SMCU" },
> + { .event = 0, .desc = NULL },
> +};
> +
> +static u64 print_event_list(int *err, char **buf, size_t *buf_len,
> + const struct ev_string *ev_strings, u64 payload)
> +{
> + for (const struct ev_string *ev = ev_strings; ev->desc != NULL; ev++) {
> + if (payload & BIT(ev->event))
> + arm_spe_pkt_out_string(err, buf, buf_len, " %s", ev->desc);
> + payload &= ~BIT(ev->event);
Sashiko has a bunch of worries in these patches about 32-bit builds:
https://sashiko.dev/#/patchset/20260401-james-spe-impdef-decode-v1-0-ad0d372c220c%40linaro.org
The one here is:
"""
Since payload is a u64, does using ~BIT(ev->event) unintentionally clear
the upper 32 bits on 32-bit architectures?
On 32-bit systems, BIT() evaluates to a 32-bit unsigned long. The bitwise
NOT operation creates a 32-bit mask, which is then zero-extended to 64 bits
during the compound assignment to the payload.
This would discard bits 32-63, contradicting the intent mentioned in the
commit message to preserve the remaining unknown impdef bits for later
printing.
Would using BIT_ULL() be safer here to ensure a 64-bit inverted mask?
"""
Thanks,
Ian
> + }
> + return payload;
> +}
> +
> static int arm_spe_pkt_desc_event(const struct arm_spe_pkt *packet,
> char *buf, size_t buf_len)
> {
> @@ -283,51 +325,7 @@ static int arm_spe_pkt_desc_event(const struct arm_spe_pkt *packet,
> int err = 0;
>
> arm_spe_pkt_out_string(&err, &buf, &buf_len, "EV");
> -
> - if (payload & BIT(EV_EXCEPTION_GEN))
> - arm_spe_pkt_out_string(&err, &buf, &buf_len, " EXCEPTION-GEN");
> - if (payload & BIT(EV_RETIRED))
> - arm_spe_pkt_out_string(&err, &buf, &buf_len, " RETIRED");
> - if (payload & BIT(EV_L1D_ACCESS))
> - arm_spe_pkt_out_string(&err, &buf, &buf_len, " L1D-ACCESS");
> - if (payload & BIT(EV_L1D_REFILL))
> - arm_spe_pkt_out_string(&err, &buf, &buf_len, " L1D-REFILL");
> - if (payload & BIT(EV_TLB_ACCESS))
> - arm_spe_pkt_out_string(&err, &buf, &buf_len, " TLB-ACCESS");
> - if (payload & BIT(EV_TLB_WALK))
> - arm_spe_pkt_out_string(&err, &buf, &buf_len, " TLB-REFILL");
> - if (payload & BIT(EV_NOT_TAKEN))
> - arm_spe_pkt_out_string(&err, &buf, &buf_len, " NOT-TAKEN");
> - if (payload & BIT(EV_MISPRED))
> - arm_spe_pkt_out_string(&err, &buf, &buf_len, " MISPRED");
> - if (payload & BIT(EV_LLC_ACCESS))
> - arm_spe_pkt_out_string(&err, &buf, &buf_len, " LLC-ACCESS");
> - if (payload & BIT(EV_LLC_MISS))
> - arm_spe_pkt_out_string(&err, &buf, &buf_len, " LLC-REFILL");
> - if (payload & BIT(EV_REMOTE_ACCESS))
> - arm_spe_pkt_out_string(&err, &buf, &buf_len, " REMOTE-ACCESS");
> - if (payload & BIT(EV_ALIGNMENT))
> - arm_spe_pkt_out_string(&err, &buf, &buf_len, " ALIGNMENT");
> - if (payload & BIT(EV_TRANSACTIONAL))
> - arm_spe_pkt_out_string(&err, &buf, &buf_len, " TXN");
> - if (payload & BIT(EV_PARTIAL_PREDICATE))
> - arm_spe_pkt_out_string(&err, &buf, &buf_len, " SVE-PARTIAL-PRED");
> - if (payload & BIT(EV_EMPTY_PREDICATE))
> - arm_spe_pkt_out_string(&err, &buf, &buf_len, " SVE-EMPTY-PRED");
> - if (payload & BIT(EV_L2D_ACCESS))
> - arm_spe_pkt_out_string(&err, &buf, &buf_len, " L2D-ACCESS");
> - if (payload & BIT(EV_L2D_MISS))
> - arm_spe_pkt_out_string(&err, &buf, &buf_len, " L2D-MISS");
> - if (payload & BIT(EV_CACHE_DATA_MODIFIED))
> - arm_spe_pkt_out_string(&err, &buf, &buf_len, " HITM");
> - if (payload & BIT(EV_RECENTLY_FETCHED))
> - arm_spe_pkt_out_string(&err, &buf, &buf_len, " LFB");
> - if (payload & BIT(EV_DATA_SNOOPED))
> - arm_spe_pkt_out_string(&err, &buf, &buf_len, " SNOOPED");
> - if (payload & BIT(EV_STREAMING_SVE_MODE))
> - arm_spe_pkt_out_string(&err, &buf, &buf_len, " STREAMING-SVE");
> - if (payload & BIT(EV_SMCU))
> - arm_spe_pkt_out_string(&err, &buf, &buf_len, " SMCU");
> + print_event_list(&err, &buf, &buf_len, common_ev_strings, payload);
>
> return err;
> }
>
> --
> 2.34.1
>
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