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[ Upstream commitfd380097cd] 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 to avoid overflow. Fixes:22f429f19c("coresight: etm-perf: Add support for ETR backend") Fixes:99443ea19e("coresight: Add generic TMC sg table framework") Fixes:2e499bbc1a("coresight: tmc: implementing TMC-ETF AUX space API") Signed-off-by: Ruidong Tian <tianruidong@linux.alibaba.com> Reviewed-by: James Clark <james.clark@arm.com> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Link: https://lore.kernel.org/r/20230804081514.120171-2-tianruidong@linux.alibaba.com Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.