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  • Benjamin Herrenschmidt's avatar
    powerpc: Use names rather than numbers for SPRGs (v2) · ee43eb78
    Benjamin Herrenschmidt authored
    
    
    The kernel uses SPRG registers for various purposes, typically in
    low level assembly code as scratch registers or to hold per-cpu
    global infos such as the PACA or the current thread_info pointer.
    
    We want to be able to easily shuffle the usage of those registers
    as some implementations have specific constraints realted to some
    of them, for example, some have userspace readable aliases, etc..
    and the current choice isn't always the best.
    
    This patch should not change any code generation, and replaces the
    usage of SPRN_SPRGn everywhere in the kernel with a named replacement
    and adds documentation next to the definition of the names as to
    what those are used for on each processor family.
    
    The only parts that still use the original numbers are bits of KVM
    or suspend/resume code that just blindly needs to save/restore all
    the SPRGs.
    
    Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
    ee43eb78