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SubjectRe: [PATCH v1 2/2] perf bpf filter: Support pre-5.16 kernels
On Fri, Apr 7, 2023 at 10:52 PM Ian Rogers <irogers@google.com> wrote:
>
> The mem_hops bits were added in 5.16 with no prior equivalent.
>
> Signed-off-by: Ian Rogers <irogers@google.com>

Acked-by: Namhyung Kim <namhyung@kernel.org>

Thanks,
Namhyung


> ---
> tools/perf/util/bpf_skel/sample_filter.bpf.c | 28 ++++++++++++++++++--
> 1 file changed, 26 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/util/bpf_skel/sample_filter.bpf.c b/tools/perf/util/bpf_skel/sample_filter.bpf.c
> index 57e3c67d6d37..cffe493af1ed 100644
> --- a/tools/perf/util/bpf_skel/sample_filter.bpf.c
> +++ b/tools/perf/util/bpf_skel/sample_filter.bpf.c
> @@ -24,6 +24,24 @@ struct perf_sample_data___new {
> __u64 sample_flags;
> } __attribute__((preserve_access_index));
>
> +/* new kernel perf_mem_data_src definition */
> +union perf_mem_data_src__new {
> + __u64 val;
> + struct {
> + __u64 mem_op:5, /* type of opcode */
> + mem_lvl:14, /* memory hierarchy level */
> + mem_snoop:5, /* snoop mode */
> + mem_lock:2, /* lock instr */
> + mem_dtlb:7, /* tlb access */
> + mem_lvl_num:4, /* memory hierarchy level number */
> + mem_remote:1, /* remote */
> + mem_snoopx:2, /* snoop mode, ext */
> + mem_blk:3, /* access blocked */
> + mem_hops:3, /* hop level */
> + mem_rsvd:18;
> + };
> +};
> +
> /* helper function to return the given perf sample data */
> static inline __u64 perf_get_sample(struct bpf_perf_event_data_kern *kctx,
> struct perf_bpf_filter_entry *entry)
> @@ -89,8 +107,14 @@ static inline __u64 perf_get_sample(struct bpf_perf_event_data_kern *kctx,
> return kctx->data->data_src.mem_dtlb;
> if (entry->part == 7)
> return kctx->data->data_src.mem_blk;
> - if (entry->part == 8)
> - return kctx->data->data_src.mem_hops;
> + if (entry->part == 8) {
> + union perf_mem_data_src__new *data = (void *)&kctx->data->data_src;
> +
> + if (bpf_core_field_exists(data->mem_hops))
> + return data->mem_hops;
> +
> + return 0;
> + }
> /* return the whole word */
> return kctx->data->data_src.val;
> default:
> --
> 2.40.0.577.gac1e443424-goog
>

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