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2c5e88dc90
Rework CAAM RNG implementation as follows: - Make use of the fact that HWRNG supports partial reads and will handle such cases gracefully by removing recursion in caam_read() - Convert blocking caam_read() codepath to do a single blocking job read directly into requested buffer, bypassing any intermediary buffers - Convert async caam_read() codepath into a simple single reader/single writer FIFO use-case, thus simplifying concurrency handling and delegating buffer read/write position management to KFIFO subsystem. - Leverage the same low level RNG data extraction code for both async and blocking caam_read() scenarios, get rid of the shared job descriptor and make non-shared one as a simple as possible (just HEADER + ALGORITHM OPERATION + FIFO STORE) - Split private context from DMA related memory, so that the former could be allocated without GFP_DMA. NOTE: On its face value this commit decreased throughput numbers reported by dd if=/dev/hwrng of=/dev/null bs=1 count=100K [iflag=nonblock] by about 15%, however commits that enable prediction resistance and limit JR total size impact the performance so much and move the bottleneck such as to make this regression irrelevant. NOTE: On the bright side, this commit reduces RNG in kernel DMA buffer memory usage from 2 x RN_BUF_SIZE (~256K) to 32K. Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com> Reviewed-by: Horia Geantă <horia.geanta@nxp.com> Cc: Chris Healy <cphealy@gmail.com> Cc: Lucas Stach <l.stach@pengutronix.de> Cc: Horia Geantă <horia.geanta@nxp.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Iuliana Prodan <iuliana.prodan@nxp.com> Cc: linux-crypto@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-imx@nxp.com Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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.