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SubjectRe: [PATCH v3 4/4] arm64: mm: Implement pte_devmap support
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On 24/05/2019 19:08, Will Deacon wrote:
> On Thu, May 23, 2019 at 04:03:16PM +0100, Robin Murphy wrote:
>> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
>> index 2c41b04708fe..a6378625d47c 100644
>> --- a/arch/arm64/include/asm/pgtable.h
>> +++ b/arch/arm64/include/asm/pgtable.h
>> @@ -90,6 +90,7 @@ extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)];
>> #define pte_write(pte) (!!(pte_val(pte) & PTE_WRITE))
>> #define pte_user_exec(pte) (!(pte_val(pte) & PTE_UXN))
>> #define pte_cont(pte) (!!(pte_val(pte) & PTE_CONT))
>> +#define pte_devmap(pte) (!!(pte_val(pte) & PTE_DEVMAP))
>>
>> #define pte_cont_addr_end(addr, end) \
>> ({ unsigned long __boundary = ((addr) + CONT_PTE_SIZE) & CONT_PTE_MASK; \
>> @@ -217,6 +218,11 @@ static inline pmd_t pmd_mkcont(pmd_t pmd)
>> return __pmd(pmd_val(pmd) | PMD_SECT_CONT);
>> }
>>
>> +static inline pte_t pte_mkdevmap(pte_t pte)
>> +{
>> + return set_pte_bit(pte, __pgprot(PTE_DEVMAP));
>> +}
>> +
>> static inline void set_pte(pte_t *ptep, pte_t pte)
>> {
>> WRITE_ONCE(*ptep, pte);
>> @@ -381,6 +387,9 @@ static inline int pmd_protnone(pmd_t pmd)
>>
>> #define pmd_mkhuge(pmd) (__pmd(pmd_val(pmd) & ~PMD_TABLE_BIT))
>>
>> +#define pmd_devmap(pmd) pte_devmap(pmd_pte(pmd))
>> +#define pmd_mkdevmap(pmd) pte_pmd(pte_mkdevmap(pmd_pte(pmd)))
>> +
>> #define __pmd_to_phys(pmd) __pte_to_phys(pmd_pte(pmd))
>> #define __phys_to_pmd_val(phys) __phys_to_pte_val(phys)
>> #define pmd_pfn(pmd) ((__pmd_to_phys(pmd) & PMD_MASK) >> PAGE_SHIFT)
>> @@ -537,6 +546,11 @@ static inline phys_addr_t pud_page_paddr(pud_t pud)
>> return __pud_to_phys(pud);
>> }
>>
>> +static inline int pud_devmap(pud_t pud)
>> +{
>> + return 0;
>> +}
>> +
>> /* Find an entry in the second-level page table. */
>> #define pmd_index(addr) (((addr) >> PMD_SHIFT) & (PTRS_PER_PMD - 1))
>>
>> @@ -624,6 +638,11 @@ static inline phys_addr_t pgd_page_paddr(pgd_t pgd)
>>
>> #define pgd_ERROR(pgd) __pgd_error(__FILE__, __LINE__, pgd_val(pgd))
>>
>> +static inline int pgd_devmap(pgd_t pgd)
>> +{
>> + return 0;
>> +}
>
> I think you need to guard this and pXd_devmap() with
> CONFIG_TRANSPARENT_HUGEPAGE, otherwise you'll conflict with the dummy
> definitions in mm.h and the build will fail.

Ah, right you are - I got as far as catching similar issues with
CONFIG_PGTABLE_LEVELS, but apparently I failed to spot the !THP guards
in x86 and powerpc. Let me give this one a tweak and test a wider range
of configs...

Robin.

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