perf cs-etm: Avoid truncating AUX buffer sizes to int

cs_etm__get_trace() returns an int, but it used to return etmq->buf_len
on success. That value comes from auxtrace_buffer::size, which is a
size_t. For a large AUX trace block, returning the byte count through an
int can overflow and make a valid buffer look like a negative error.

The callers do not need the actual byte count from cs_etm__get_trace().
The buffer length is already stored in the etmq->buf_len. The callers
only need to distinguish three states:

  < 0: error
  = 0: no more AUX buffers
  > 0: data is available

Make cs_etm__get_trace() return 0 for all non-error cases and use
etmq->buf_len to indicate whether a new buffer was found. Then make
cs_etm__get_data_block() return 1 whenever data is available, instead of
returning the buffer length.

Also refactor cs_etm__get_data_block() to make its return value
semantics clearer.

Reported-by: Suyash Mahar <smahar@meta.com>
Fixes: 8224531cf5a1 ("perf cs-etm: Modularize auxtrace_buffer fetch function")
Signed-off-by: Leo Yan <leo.yan@arm.com>
Reviewed-by: James Clark <james.clark@linaro.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

0 files changed, 0 insertions, 0 deletions