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    arm64/sve: Add prctl controls for userspace vector length management · 2d2123bc
    Dave Martin 提交于
    This patch adds two arm64-specific prctls, to permit userspace to
    control its vector length:
    
     * PR_SVE_SET_VL: set the thread's SVE vector length and vector
       length inheritance mode.
    
     * PR_SVE_GET_VL: get the same information.
    
    Although these prctls resemble instruction set features in the SVE
    architecture, they provide additional control: the vector length
    inheritance mode is Linux-specific and nothing to do with the
    architecture, and the architecture does not permit EL0 to set its
    own vector length directly.  Both can be used in portable tools
    without requiring the use of SVE instructions.
    Signed-off-by: NDave Martin <Dave.Martin@arm.com>
    Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com>
    Cc: Alex Bennée <alex.bennee@linaro.org>
    [will: Fixed up prctl constants to avoid clash with PDEATHSIG]
    Signed-off-by: NWill Deacon <will.deacon@arm.com>
    2d2123bc
processor.h 5.7 KB