[PATCH 0/4] arm64: an optimization for AmpereOne

[Huang Shijie <shijie@os.amperecomputing.com>]

0) Background:
   We found that AmpereOne benefits from aggressive prefetches when
   using 4K page size.

1) This patch:
    1.1) adds new WORKAROUND_AMPERE_AC03_PREFETCH capability.
    1.2) uses MIDR_AMPERE1 to filter the processor.
    1.3) uses alternative_if to alternative the code
         for AmpereOne.
    1.4) adds software prefetches for the specific loop.
    	 Also add a macro add_prefetch.

2) Test result:
    In hugetlb or tmpfs, We can get big seqential read performance improvement
    up to 1.3x ~ 1.4x.


Huang Shijie (4):
  extable: add __sort_main_extable
  arm64: alternative: handle the kernel exception table
  arm64: copy_template.S: add loop_for_copy_128_bytes macro
  arm64: add software prefetches for AmpereOne

 arch/arm64/Kconfig.platforms    |  7 +++
 arch/arm64/kernel/alternative.c | 18 +++++++
 arch/arm64/kernel/cpu_errata.c  |  9 ++++
 arch/arm64/lib/copy_template.S  | 87 +++++++++++++++++++++++----------
 arch/arm64/tools/cpucaps        |  1 +
 include/linux/extable.h         |  2 +
 kernel/extable.c                |  8 ++-
 7 files changed, 105 insertions(+), 27 deletions(-)

-- 
2.40.1