perf session: Add byte-swap handler for PERF_RECORD_COMPRESSED2

PERF_RECORD_COMPRESSED2 events carry a data_size field that must be
byte-swapped when reading cross-endian perf.data files.  Without a
swap handler, reading COMPRESSED2 events on a different-endian machine
would misinterpret data_size as a garbage value, causing the
decompression path to read the wrong number of bytes.

The compressed payload itself is a raw byte stream and needs no
swapping.

Fixes: 208c0e16834472bb ("perf record: Add 8-byte aligned event type PERF_RECORD_COMPRESSED2")
Reported-by: sashiko-bot@kernel.org # Running on a local machine
Reviewed-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Chun-Tse Shao <ctshao@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Assisted-by: Claude:claude-opus-4.6-1m
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 8280413f4528f53c4129f4565c308109f031fb79..9271885e3920f897c075c34209c868cc41177bcc 100644 (file)
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1056,6 +1056,14 @@ static int perf_event__time_conv_swap(union perf_event *event,
        return 0;
 }
 
+static int perf_event__compressed2_swap(union perf_event *event,
+                                       bool sample_id_all __maybe_unused)
+{
+       /* Only data_size needs swapping — compressed payload is a raw byte stream */
+       event->pack2.data_size = bswap_64(event->pack2.data_size);
+       return 0;
+}
+
 static int perf_event__bpf_metadata_swap(union perf_event *event,
                                         bool sample_id_all __maybe_unused)
 {
@@ -1197,6 +1205,7 @@ static perf_event__swap_op perf_event__swap_ops[] = {
        [PERF_RECORD_STAT_ROUND]          = perf_event__stat_round_swap,
        [PERF_RECORD_EVENT_UPDATE]        = perf_event__event_update_swap,
        [PERF_RECORD_TIME_CONV]           = perf_event__time_conv_swap,
+       [PERF_RECORD_COMPRESSED2]         = perf_event__compressed2_swap,
        [PERF_RECORD_BPF_METADATA]        = perf_event__bpf_metadata_swap,
        [PERF_RECORD_SCHEDSTAT_CPU]       = perf_event__schedstat_cpu_swap,
        [PERF_RECORD_SCHEDSTAT_DOMAIN]    = perf_event__schedstat_domain_swap,