perf session: Fix handling when buffer exceeds 2 GiB

If a user specifies an AUX buffer larger than 2 GiB, the returned size
may exceed 0x80000000. Since the err variable is defined as a signed
32-bit integer, such a value overflows and becomes negative.

As a result, the perf record command reports an error:

  0x146e8 [0x30]: failed to process type: 71 [Unknown error 183711232]

Change the type of the err variable to a signed 64-bit integer to
accommodate large buffer sizes correctly.

Fixes: d5652d8 ("perf session: Add ability to skip 4GiB or more")
Reported-by: Tamas Zsoldos <[email protected]>
Signed-off-by: Leo Yan <[email protected]>
Acked-by: Namhyung Kim <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Ian Rogers <[email protected]>
Cc: Jiri Olsa <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: Leo-Yan

tools/perf/util/session.c

@@ -1402,7 +1402,7 @@ static s64 perf_session__process_user_event(struct perf_session *session,
 	const struct perf_tool *tool = session->tool;
 	struct perf_sample sample;
 	int fd = perf_data__fd(session->data);
-	int err;
+	s64 err;
 
 	perf_sample__init(&sample, /*all=*/true);
 	if ((event->header.type != PERF_RECORD_COMPRESSED &&