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SubjectRe: [RFC][PATCH 1/4] arm64: Drop alloc function from create_mapping
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On 01/26/2016 03:22 AM, Mark Rutland wrote:
> On Mon, Jan 25, 2016 at 08:52:12AM -0800, Laura Abbott wrote:
>> create_mapping is only used in fixmap_remap_fdt. All the create_mapping
>> calls need to happen on existing translation table pages without
>> additional allocations. Rather than have an alloc function be called
>> and fail, just set it to NULL and catch it's use.
>
> This looks sensible to me, though I think we should rename
> create_mapping to something that makes it clear that not allocating
> pages is a deliberate design decision, and thus it must be called with
> care.
>
> Perhaps create_mapping_noalloc?

I was wondering about that. That name sounds clearer.

>
> Thanks,
> Mark.
>
>> Signed-off-by: Laura Abbott <labbott@fedoraproject.org>
>> ---
>> arch/arm64/mm/mmu.c | 14 ++++++++++----
>> 1 file changed, 10 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
>> index e141762..2d6e7cf 100644
>> --- a/arch/arm64/mm/mmu.c
>> +++ b/arch/arm64/mm/mmu.c
>> @@ -116,7 +116,9 @@ static void alloc_init_pte(pmd_t *pmd, unsigned long addr,
>> pte_t *pte;
>>
>> if (pmd_none(*pmd) || pmd_sect(*pmd)) {
>> - phys_addr_t pte_phys = pgtable_alloc();
>> + phys_addr_t pte_phys;
>> + BUG_ON(!pgtable_alloc);
>> + pte_phys = pgtable_alloc();
>> pte = pte_fixmap(pte_phys);
>> if (pmd_sect(*pmd))
>> split_pmd(pmd, pte);
>> @@ -158,7 +160,9 @@ static void alloc_init_pmd(pud_t *pud, unsigned long addr, unsigned long end,
>> * Check for initial section mappings in the pgd/pud and remove them.
>> */
>> if (pud_none(*pud) || pud_sect(*pud)) {
>> - phys_addr_t pmd_phys = pgtable_alloc();
>> + phys_addr_t pmd_phys;
>> + BUG_ON(!pgtable_alloc);
>> + pmd_phys = pgtable_alloc();
>> pmd = pmd_fixmap(pmd_phys);
>> if (pud_sect(*pud)) {
>> /*
>> @@ -223,7 +227,9 @@ static void alloc_init_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
>> unsigned long next;
>>
>> if (pgd_none(*pgd)) {
>> - phys_addr_t pud_phys = pgtable_alloc();
>> + phys_addr_t pud_phys;
>> + BUG_ON(!pgtable_alloc);
>> + pud_phys = pgtable_alloc();
>> __pgd_populate(pgd, pud_phys, PUD_TYPE_TABLE);
>> }
>> BUG_ON(pgd_bad(*pgd));
>> @@ -319,7 +325,7 @@ static void __init create_mapping(phys_addr_t phys, unsigned long virt,
>> return;
>> }
>> __create_pgd_mapping(init_mm.pgd, phys, virt, size, prot,
>> - early_pgtable_alloc);
>> + NULL);
>> }
>>
>> void __init create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
>> --
>> 2.5.0
>>

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