On Mon, May 04, 2009 at 11:54:33AM +0200, Johannes Weiner wrote:
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
> ---
> mm/memory.c | 37 ++++++-------------------------------
> 1 files changed, 6 insertions(+), 31 deletions(-)
>
> diff --git a/mm/memory.c b/mm/memory.c
> index a621319..aee167d 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -3051,50 +3051,25 @@ int follow_phys(struct vm_area_struct *vma,
> unsigned long address, unsigned int flags,
> unsigned long *prot, resource_size_t *phys)
> {
> - pgd_t *pgd;
> - pud_t *pud;
> - pmd_t *pmd;
> + int ret = -EINVAL;
> pte_t *ptep, pte;
> spinlock_t *ptl;
> - resource_size_t phys_addr = 0;
> - struct mm_struct *mm = vma->vm_mm;
> - int ret = -EINVAL;
>
> if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
> goto out;
>
> - pgd = pgd_offset(mm, address);
> - if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
> - goto out;
> -
> - pud = pud_offset(pgd, address);
> - if (pud_none(*pud) || unlikely(pud_bad(*pud)))
> - goto out;
> -
> - pmd = pmd_offset(pud, address);
> - if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
> - goto out;
> -
> - /* We cannot handle huge page PFN maps. Luckily they don't exist. */
> - if (pmd_huge(*pmd))
> + if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
> goto out;
> -
> - ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
> - if (!ptep)
> - goto out;
> -
> pte = *ptep;
> - if (!pte_present(pte))
> - goto unlock;
> +
> if ((flags & FOLL_WRITE) && !pte_write(pte))
> goto unlock;
> - phys_addr = pte_pfn(pte);
> - phys_addr <<= PAGE_SHIFT; /* Shift here to avoid overflow on PAE */
>
> *prot = pgprot_val(pte_pgprot(pte));
> - *phys = phys_addr;
> - ret = 0;
> + /* Shift here to avoid overflow on PAE */
> + *phys = pte_pfn(pte) << PAGE_SHIFT;
Yuk, had my head in the butt here. Changed to
*phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
---
From: Johannes Weiner <hannes@xxxxxxxxxxx>
Subject: mm: use generic follow_pte() in follow_phys()
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
---
mm/memory.c | 36 +++++-------------------------------
1 files changed, 5 insertions(+), 31 deletions(-)
diff --git a/mm/memory.c b/mm/memory.c
index a621319..c047950 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3051,50 +3051,24 @@ int follow_phys(struct vm_area_struct *vma,
unsigned long address, unsigned int flags,
unsigned long *prot, resource_size_t *phys)
{
- pgd_t *pgd;
- pud_t *pud;
- pmd_t *pmd;
+ int ret = -EINVAL;
pte_t *ptep, pte;
spinlock_t *ptl;
- resource_size_t phys_addr = 0;
- struct mm_struct *mm = vma->vm_mm;
- int ret = -EINVAL;
if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
goto out;
- pgd = pgd_offset(mm, address);
- if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
- goto out;
-
- pud = pud_offset(pgd, address);
- if (pud_none(*pud) || unlikely(pud_bad(*pud)))
- goto out;
-
- pmd = pmd_offset(pud, address);
- if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
- goto out;
-
- /* We cannot handle huge page PFN maps. Luckily they don't exist. */
- if (pmd_huge(*pmd))
+ if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
goto out;
-
- ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
- if (!ptep)
- goto out;
-
pte = *ptep;
- if (!pte_present(pte))
- goto unlock;
+
if ((flags & FOLL_WRITE) && !pte_write(pte))
goto unlock;
- phys_addr = pte_pfn(pte);
- phys_addr <<= PAGE_SHIFT; /* Shift here to avoid overflow on PAE */
*prot = pgprot_val(pte_pgprot(pte));
- *phys = phys_addr;
- ret = 0;
+ *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
+ ret = 0;
unlock:
pte_unmap_unlock(ptep, ptl);
out:
--
1.6.2.1.135.gde769
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