Re: [PATCH v4 2/3] arm64: Implement page table free interfaces

Chintan Pandya
2018-03-27T04:38:14Z

On 3/26/2018 3:25 PM, Mark Rutland wrote:
> On Tue, Mar 20, 2018 at 05:15:13PM +0530, Chintan Pandya wrote:
>> +static int __pmd_free_pte_page(pmd_t *pmd, unsigned long addr, bool tlb_inv)
>> +{
>> + pmd_t *table;
>> +
>> + if (pmd_val(*pmd)) {
>> + table = __va(pmd_val(*pmd));
>> + pmd_clear(pmd);
>> + /*
>> + * FIXME: __flush_tlb_pgtable(&init_mm, addr) is
>> + * ideal candidate here, which exactly
>> + * flushes intermediate pgtables. But,
>> + * this is broken (evident from tests).
>> + * So, use safe TLB op unless that is fixed.
>> + */
>> + if (tlb_inv)
>> + flush_tlb_kernel_range(addr, addr + PMD_SIZE);
>
> I don't think that __flush_tlb_pgtable() is broken. It's only valid to
> call it for user page tables, since it doesn't affect all ASIDs.
>
> We can add a simlar helper for kernel mappings, which affects all ASIDs,
> e.g.
>
Okay. I will test it and update v5.

> static inline void __flush_tlb_kernel_pgtable(unsigned long addr)
> {
> addr >>= 12;
> __tlbi(vaae1is, addr);
> dsb(ish);
> }
>
> Thanks,
> Mark.
>

Chintan
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