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[v3,0/2] use static key to optimize pgtable_l4_enabled

Message ID 20220519155918.3882-1-jszhang@kernel.org (mailing list archive)
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Series use static key to optimize pgtable_l4_enabled | expand


Jisheng Zhang May 19, 2022, 3:59 p.m. UTC
The pgtable_l4|[l5]_enabled check sits at hot code path, performance
is impacted a lot. Since pgtable_l4|[l5]_enabled isn't changed after
boot, so static key can be used to solve the issue[1].

An unified way static key was introduced in [2], but it's only targets
riscv isa extension. We dunno whether SV48 and SV57 will be considered
as isa extension, so the unified solution isn't used for

patch1 fix a NULL pointer deference if static key is used a bit earlier.
patch2 uses the static key to optimize pgtable_l4|[l5]_enabled.

[1] http://lists.infradead.org/pipermail/linux-riscv/2021-December/011164.html
[2] https://lore.kernel.org/linux-riscv/20220517184453.3558-1-jszhang@kernel.org/T/#t

Since v2:
 - move the W=1 warning fix to a separate patch
 - move the unified way to use static key to a new patch series.

Since v1:
 - Add a W=1 warning fix
 - Fix W=1 error
 - Based on v5.18-rcN, since SV57 support is added, so convert
   pgtable_l5_enabled as well.

Jisheng Zhang (2):
  riscv: move sbi_init() earlier before jump_label_init()
  riscv: turn pgtable_l4|[l5]_enabled to static key for RV64

 arch/riscv/include/asm/pgalloc.h    | 16 ++++----
 arch/riscv/include/asm/pgtable-32.h |  3 ++
 arch/riscv/include/asm/pgtable-64.h | 59 +++++++++++++++++---------
 arch/riscv/include/asm/pgtable.h    |  5 +--
 arch/riscv/kernel/cpu.c             |  4 +-
 arch/riscv/kernel/setup.c           |  2 +-
 arch/riscv/mm/init.c                | 64 ++++++++++++++++++-----------
 arch/riscv/mm/kasan_init.c          | 16 ++++----
 8 files changed, 103 insertions(+), 66 deletions(-)