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Code sections in s390 specific kernel code which use floating point or vector registers all come with a 520 byte stack variable to save already in use registers, if required. With INIT_STACK_ALL_PATTERN or INIT_STACK_ALL_ZERO enabled this variable will always be initialized on function entry in addition to saving register contents, which contradicts the intention (performance improvement) of such code sections. Therefore provide a DECLARE_KERNEL_FPU_ONSTACK() macro which provides struct kernel_fpu variables with an __uninitialized attribute, and convert all existing code to use this. This way only this specific type of stack variable will not be initialized, regardless of config options. Reviewed-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20240205154844.3757121-3-hca@linux.ibm.com Signed-off-by: Heiko Carstens <hca@linux.ibm.com>