As mentioned in http://lists.infradead.org/pipermail/linux-arm-kernel/2016-February/404146.html copy_template was left alone at the time which mentions: "since the template really deals with 64 bytes per iteration, which would need changing". The problem is that there is not enough registers available to do 128 bytes at a time. There is only enough registers to do 96 bytes at a time. If we did not have to save dst or keep x5 free (that is used by the exception case) or keep around the count; then we would have enough caller saved registers free to copy 128 bytes at a time. For user space, we will be using the SIMD registers which allows for not using any callee saved registers and get better performance.
So basically this is my old patch which just patches in the prfm to copy_template updated for the new name of the define and for the nop not needed to be there any more. Andrew Pinski (1): arm64: lib: patch in prfm for copy_template if requested arch/arm64/lib/copy_template.S | 9 ++++++++- arch/arm64/lib/memcpy.S | 3 +++ 2 files changed, 11 insertions(+), 1 deletion(-) -- 2.7.4
