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f80d034086
For consistency, all tasks have a pt_regs reserved at the highest portion of their task stack. Among other things, this ensures that a task's SP is always pointing within its stack rather than pointing immediately past the end. While it is never legitimate to ERET from a kthread, we take pains to initialize pt_regs for kthreads as if this were legitimate. As this is never legitimate, the effects of an erroneous return are rarely tested. Let's simplify things by initializing a kthread's pt_regs such that an ERET is caught as an illegal exception return, and removing the explicit initialization of other exception context. Note that as spectre_v4_enable_task_mitigation() only manipulates the PSTATE within the unused regs this is safe to remove. As user tasks will have their exception context initialized via start_thread() or start_compat_thread(), this should only impact cases where something has gone very wrong and we'd like that to be clearly indicated. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Christoph Hellwig <hch@lst.de> Cc: James Morse <james.morse@arm.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20201113124937.20574-2-mark.rutland@arm.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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.