Perf cs_etm session executed unexpectedly when AUX buffer > 1G.
perf record -C 0 -m ,2G -e cs_etm// -- <workload> [ perf record: Captured and wrote 2.615 MB perf.data ]
Perf only collect about 2M perf data rather than 2G. This is becasuse the operation, "nr_pages << PAGE_SHIFT", in coresight tmc driver, will overflow when nr_pages >= 0x80000(correspond to 1G AUX buffer). The overflow cause buffer allocation to fail, and TMC driver will alloc minimal buffer size(1M). You can just get about 2M perf data(1M AUX buffer + perf data header) at least.
Explicit convert nr_pages to 64 bit in tmc driver to avoid overflow.
Changes in V2: Suzuki K Poulose: Add another 2 places where needed to fix.
Changes in V1: James Clark: Use a more accurate commit message.
Ruidong Tian (1): coresight: tmc: Explicit type conversions to prevent integer overflow
drivers/hwtracing/coresight/coresight-tmc-etf.c | 2 +- drivers/hwtracing/coresight/coresight-tmc-etr.c | 5 +++-- drivers/hwtracing/coresight/coresight-tmc.h | 2 +- 3 files changed, 5 insertions(+), 4 deletions(-)