Messages in this thread Patch in this message |  | | From | Jinyu Tang <> | Subject | [PATCH v1] riscv: support arch_has_hw_pte_young() | Date | Sun, 29 Jan 2023 14:49:56 +0800 |
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The arch_has_hw_pte_young() is false for riscv by default. If it's false, page table walk is almost skipped for MGLRU reclaim. And it will also cause useless step in __wp_page_copy_user().
RISC-V Privileged Book says that riscv have two schemes to manage A and D bit.
So add a config for selecting, the default is true. For simple implementation riscv CPU which just generate page fault, unselect it.
Signed-off-by: Jinyu Tang <tjytimi@163.com> --- arch/riscv/Kconfig | 10 ++++++++++ arch/riscv/include/asm/pgtable.h | 7 +++++++ 2 files changed, 17 insertions(+)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index e2b656043abf..17c82885549c 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -180,6 +180,16 @@ config PAGE_OFFSET default 0x80000000 if 64BIT && !MMU default 0xff60000000000000 if 64BIT +config ARCH_HAS_HARDWARE_PTE_YOUNG + bool "Hardware Set PTE Access Bit" + default y + help + Select if hardware set A bit when PTE is accessed. The default is + 'Y', because most RISC-V CPU hardware can manage A and D bit. + But RISC-V may have simple implementation that do not support + hardware set A bit but only generate page fault, for that case just + unselect it. + config KASAN_SHADOW_OFFSET hex depends on KASAN_GENERIC diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h index 4eba9a98d0e3..1db54ab4e1ba 100644 --- a/arch/riscv/include/asm/pgtable.h +++ b/arch/riscv/include/asm/pgtable.h @@ -532,6 +532,13 @@ static inline int ptep_clear_flush_young(struct vm_area_struct *vma, */ return ptep_test_and_clear_young(vma, address, ptep); } +#ifdef CONFIG_ARCH_HAS_HARDWARE_PTE_YOUNG +#define arch_has_hw_pte_young arch_has_hw_pte_young +static inline bool arch_has_hw_pte_young(void) +{ + return true; +} +#endif #define pgprot_noncached pgprot_noncached static inline pgprot_t pgprot_noncached(pgprot_t _prot) -- 2.30.2
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