[PATCH v6 RESEND 0/2] use static key to optimize pgtable_l4_enabled

* [PATCH v6 RESEND 0/2] use static key to optimize pgtable_l4_enabled
@ 2022-08-21 14:09 Jisheng Zhang
  2022-08-21 14:09 ` [PATCH v6 RESEND 1/2] riscv: move sbi_init() earlier before jump_label_init() Jisheng Zhang
                   ` (2 more replies)
  0 siblings, 3 replies; 10+ messages in thread
From: Jisheng Zhang @ 2022-08-21 14:09 UTC (permalink / raw)
  To: Paul Walmsley, Palmer Dabbelt, Albert Ou, Andrey Ryabinin,
	Alexander Potapenko, Andrey Konovalov, Dmitry Vyukov,
	Vincenzo Frascino, Alexandre Ghiti
  Cc: linux-riscv, linux-kernel, kasan-dev

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 performance issue[1].

An unified way static key was introduced in [2], but it 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
pgtable_l4[l5]_enabled now.

patch1 fixes 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 v5:
 - Use DECLARE_STATIC_KEY_FALSE

Since v4:
 - rebased on v5.19-rcN
 - collect Reviewed-by tags
 - Fix kernel panic issue if SPARSEMEM is enabled by moving the
   riscv_finalise_pgtable_lx() after sparse_init()

Since v3:
 - fix W=1 call to undeclared function 'static_branch_likely' error

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 | 60 ++++++++++++++++++---------
 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, 104 insertions(+), 66 deletions(-)

-- 
2.34.1

^ permalink raw reply	[flat|nested] 10+ messages in thread