Messages in this thread | | | Subject | Re: [RFC PATCH v3 1/2] Add support for eXclusive Page Frame Ownership (XPFO) | From | Juerg Haefliger <> | Date | Mon, 28 Nov 2016 12:15:10 +0100 |
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On 11/24/2016 11:56 AM, AKASHI Takahiro wrote: > Hi, > > I'm trying to give it a spin on arm64, but ...
Thanks for trying this.
>> +/* >> + * Update a single kernel page table entry >> + */ >> +static inline void set_kpte(struct page *page, unsigned long kaddr, >> + pgprot_t prot) { >> + unsigned int level; >> + pte_t *kpte = lookup_address(kaddr, &level); >> + >> + /* We only support 4k pages for now */ >> + BUG_ON(!kpte || level != PG_LEVEL_4K); >> + >> + set_pte_atomic(kpte, pfn_pte(page_to_pfn(page), canon_pgprot(prot))); >> +} > > As lookup_address() and set_pte_atomic() (and PG_LEVEL_4K), are arch-specific, > would it be better to put the whole definition into arch-specific part?
Well yes but I haven't really looked into splitting up the arch specific stuff.
>> + /* >> + * Map the page back into the kernel if it was previously >> + * allocated to user space. >> + */ >> + if (test_and_clear_bit(PAGE_EXT_XPFO_UNMAPPED, >> + &page_ext->flags)) { >> + kaddr = (unsigned long)page_address(page + i); >> + set_kpte(page + i, kaddr, __pgprot(__PAGE_KERNEL)); > > Why not PAGE_KERNEL?
Good catch, thanks!
>> + /* >> + * The page is to be allocated back to user space, so unmap it from the >> + * kernel, flush the TLB and tag it as a user page. >> + */ >> + if (atomic_dec_return(&page_ext->mapcount) == 0) { >> + BUG_ON(test_bit(PAGE_EXT_XPFO_UNMAPPED, &page_ext->flags)); >> + set_bit(PAGE_EXT_XPFO_UNMAPPED, &page_ext->flags); >> + set_kpte(page, (unsigned long)kaddr, __pgprot(0)); >> + __flush_tlb_one((unsigned long)kaddr); > > Again __flush_tlb_one() is x86-specific. > flush_tlb_kernel_range() instead?
I'll take a look. If you can tell me what the relevant arm64 equivalents are for the arch-specific functions, that would help tremendously.
Thanks for the comments!
...Juerg
> Thanks, > -Takahiro AKASHI
-- Juerg Haefliger Hewlett Packard Enterprise
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