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SubjectRe: [PATCH v4] riscv: mm: Remove the copy operation of pmd
From
On Thu, 31 Mar 2022 19:43:20 PDT (-0700), hanchuanhua@oppo.com wrote:
> Since all processes share the kernel address space,
> we only need to copy pgd in case of a vmalloc page
> fault exception, the other levels of page tables are
> shared, so the operation of copying pmd is unnecessary.
>
> Signed-off-by: Chuanhua Han <hanchuanhua@oppo.com>
> ---
> Changes in v4:
> -Modify incorrect author name.
>
> Changes in v3:
> -Change the real name of signed-off-by.
>
> Changes in v2:
> -Delete incorrect default signatures.
>
>
> arch/riscv/mm/fault.c | 10 +++-------
> 1 file changed, 3 insertions(+), 7 deletions(-)
>
> diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
> index 4e9efbe46d5f..40694f0cab9e 100644
> --- a/arch/riscv/mm/fault.c
> +++ b/arch/riscv/mm/fault.c
> @@ -102,9 +102,9 @@ static inline void bad_area(struct pt_regs *regs, struct mm_struct *mm, int code
> static inline void vmalloc_fault(struct pt_regs *regs, int code, unsigned long addr)
> {
> pgd_t *pgd, *pgd_k;
> - pud_t *pud, *pud_k;
> - p4d_t *p4d, *p4d_k;
> - pmd_t *pmd, *pmd_k;
> + pud_t *pud_k;
> + p4d_t *p4d_k;
> + pmd_t *pmd_k;
> pte_t *pte_k;
> int index;
> unsigned long pfn;
> @@ -132,14 +132,12 @@ static inline void vmalloc_fault(struct pt_regs *regs, int code, unsigned long a
> }
> set_pgd(pgd, *pgd_k);
>
> - p4d = p4d_offset(pgd, addr);
> p4d_k = p4d_offset(pgd_k, addr);
> if (!p4d_present(*p4d_k)) {
> no_context(regs, addr);
> return;
> }
>
> - pud = pud_offset(p4d, addr);
> pud_k = pud_offset(p4d_k, addr);
> if (!pud_present(*pud_k)) {
> no_context(regs, addr);
> @@ -150,13 +148,11 @@ static inline void vmalloc_fault(struct pt_regs *regs, int code, unsigned long a
> * Since the vmalloc area is global, it is unnecessary
> * to copy individual PTEs
> */
> - pmd = pmd_offset(pud, addr);
> pmd_k = pmd_offset(pud_k, addr);
> if (!pmd_present(*pmd_k)) {
> no_context(regs, addr);
> return;
> }
> - set_pmd(pmd, *pmd_k);
>
> /*
> * Make sure the actual PTE exists as well to

Thanks, this is on for-next (it was last night, but looks like I forgot
to send the email).

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