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tile: add virt_to_kpte() API and clean up and document behavior

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We use virt_to_pte(NULL, va) a lot, which isn't very obvious.
I added virt_to_kpte(va) as a more obvious wrapper function,
that also validates the va as being a kernel adddress.

And, I fixed the semantics of virt_to_pte() so that we handle
the pud and pmd the same way, and we now document the fact that
we handle the final pte level differently.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
This commit is contained in:
Chris Metcalf
2013-08-12 15:08:09 -04:00
parent 49cf78ef7b
commit 640710a33b
6 changed files with 30 additions and 11 deletions
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22
arch/tile/mm/pgtable.c
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@@ -325,6 +325,17 @@ void ptep_set_wrprotect(struct mm_struct *mm,
#endif
/*
* Return a pointer to the PTE that corresponds to the given
* address in the given page table. A NULL page table just uses
* the standard kernel page table; the preferred API in this case
* is virt_to_kpte().
*
* The returned pointer can point to a huge page in other levels
* of the page table than the bottom, if the huge page is present
* in the page table. For bottom-level PTEs, the returned pointer
* can point to a PTE that is either present or not.
*/
pte_t *virt_to_pte(struct mm_struct* mm, unsigned long addr)
{
pgd_t *pgd;
@@ -341,14 +352,21 @@ pte_t *virt_to_pte(struct mm_struct* mm, unsigned long addr)
if (pud_huge_page(*pud))
return (pte_t *)pud;
pmd = pmd_offset(pud, addr);
if (pmd_huge_page(*pmd))
return (pte_t *)pmd;
if (!pmd_present(*pmd))
return NULL;
if (pmd_huge_page(*pmd))
return (pte_t *)pmd;
return pte_offset_kernel(pmd, addr);
}
EXPORT_SYMBOL(virt_to_pte);
pte_t *virt_to_kpte(unsigned long kaddr)
{
BUG_ON(kaddr < PAGE_OFFSET);
return virt_to_pte(NULL, kaddr);
}
EXPORT_SYMBOL(virt_to_kpte);
pgprot_t set_remote_cache_cpu(pgprot_t prot, int cpu)
{
unsigned int width = smp_width;