• Will Deacon's avatar
    arm64: cacheinfo: Remove CCSIDR-based cache information probing · a8d4636f
    Will Deacon authored
    The CCSIDR_EL1.{NumSets,Associativity,LineSize} fields are only for use
    in conjunction with set/way cache maintenance and are not guaranteed to
    represent the actual microarchitectural features of a design.
    
    The architecture explicitly states:
    
    | You cannot make any inference about the actual sizes of caches based
    | on these parameters.
    
    Furthermore, CCSIDR_EL1.{WT,WB,RA,WA} have been removed retrospectively
    from ARMv8 and are now considered to be UNKNOWN.
    
    Since the kernel doesn't make use of set/way cache maintenance and it is
    not possible for userspace to execute these instructions, we have no
    need for the CCSIDR information in the kernel.
    
    This patch removes the accessors, along with the related portions of the
    cacheinfo support, which should instead be reintroduced when firmware has
    a mechanism to provide us with reliable information.
    Acked-by: default avatarMark Rutland <mark.rutland@arm.com>
    Acked-by: default avatarSudeep Holla <sudeep.holla@arm.com>
    Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
    Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
    a8d4636f
cacheinfo.c 2.86 KB