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Commit9fef686863("MIPS: Make SAVE_SOME more standard") made several changes to the order in which registers are saved in the SAVE_SOME macro, used by exception handlers to save the processor state. In particular, it removed the move k1, sp in the delay slot of the branch testing if the processor is already in kernel mode. This is replaced later in the macro by a move k0, sp When CONFIG_EVA is disabled, this instruction actually appears in the delay slot of the branch. However, when CONFIG_EVA is enabled, instead the RPS workaround of MFC0 k0, CP0_ENTRYHI appears in the delay slot. This results in k0 not containing the stack pointer, but some unrelated value, which is then saved to the kernel stack. On exit from the exception, this bogus value is restored to the stack pointer, resulting in an OOPS. Fix this by moving the save of SP in k0 explicitly in the delay slot of the branch, outside of the CONFIG_EVA section, restoring the expected instruction ordering when CONFIG_EVA is active. Fixes:9fef686863("MIPS: Make SAVE_SOME more standard") Signed-off-by: Matt Redfearn <matt.redfearn@mips.com> Reported-by: Vladimir Kondratiev <vladimir.kondratiev@intel.com> Reviewed-by: Corey Minyard <cminyard@mvista.com> Reviewed-by: James Hogan <jhogan@kernel.org> Patchwork: https://patchwork.linux-mips.org/patch/17471/ Signed-off-by: James Hogan <jhogan@kernel.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.