[PATCH] riscv: mm: Remove the copy operation of pmd
hanchuanhua
hanchuanhua at oppo.com
Tue Feb 22 18:58:12 PST 2022
On 2022/2/23 5:25, Palmer Dabbelt wrote:
> On Thu, 27 Jan 2022 02:06:22 PST (-0800), hanchuanhua at 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: hanchuanhua <hanchuanhua at oppo.com>
>> ---
>> 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 4e9efbe..40694f0 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
> This looks good, but "Signed off by" lines are supposed to have real
> names associated with them and this looks like a handle to me. There
> also seems to be something broken with the email, as this is causing git
> to blow up, but for a small patch like this that's OK as I can resurrect
> it by hand.
>
> Reviewed-by: Palmer Dabbelt <palmer at rivosinc.com> # aside from the name
>
> Please send a v2 with the proper Signed off by line, as that's not
> something I'm supposed to just fix up myself.
>
> Thanks!
First of all, thank you for your review and reply. I don't quite
understand what's wrong with the line "Signed off by"?
Thanks!
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