[PATCH v5 0/2] use static key to optimize pgtable_l4_enabled

From: Jisheng Zhang
Date: Fri Jul 15 2022 - 09:57:58 EST

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@xxxxxxxxxx/T/#t

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(-)