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commit47016b341fupstream. The current Cadence QSPI driver caused a kernel panic when loading a Root Filesystem from QSPI. The problem was caused by reading more bytes than needed because the QSPI operated on 4 bytes at a time. <snip> [ 7.947754] spi_nor_read[1048]:from 0x037cad74, len 1 [bfe07fff] [ 7.956247] cqspi_read[910]:offset 0x58502516, buffer=bfe07fff [ 7.956247] [ 7.966046] Unable to handle kernel paging request at virtual address bfe08002 [ 7.973239] pgd = eebfc000 [ 7.975931] [bfe08002] *pgd=2fffb811, *pte=00000000, *ppte=00000000 </snip> Notice above how only 1 byte needed to be read but by reading 4 bytes into the end of a mapped page, an unrecoverable page fault occurred. This patch uses a temporary buffer to hold the 4 bytes read and then copies only the bytes required into the buffer. A min() function is used to limit the length to prevent buffer overflows. Request testing of this patch on other platforms. This was tested on the Intel Arria10 SoCFPGA DevKit. Fixes:0cf1725676("mtd: spi-nor: cqspi: Fix build on arches missing readsl/writesl") Signed-off-by: Thor Thayer <thor.thayer@linux.intel.com> Cc: <stable@vger.kernel.org> Reviewed-by: Marek Vasut <marek.vasut@gmail.com> Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.