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Date: Mon, 11 May 2009 10:27:33 +0200
From: Stefan Lankes <lankes@...s.rwth-aachen.de>
To: linux-kernel@...r.kernel.org
Subject: [RFC PATCH 3/4]: affinity-on-next-touch
[Patch 3/4]: If the "untouched" bit is set, mprotect isn't permitted to
change the permission in the page table entry. By using of
"affinity-on-next-touch", the access permission will be set by the pte fault
handler.
mm/mprotect.c | 39 +++++++++++++++++++++++++++------------
1 files changed, 27 insertions(+), 12 deletions(-)
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 258197b..815aa9b 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -35,9 +35,9 @@ static inline pgprot_t pgprot_modify(pgprot_t oldprot,
pgprot_t newprot)
}
#endif
-static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
- unsigned long addr, unsigned long end, pgprot_t newprot,
- int dirty_accountable)
+static void change_pte_range(struct vm_area_struct *vma,
+ struct mm_struct *mm, pmd_t *pmd, unsigned long addr,
+ unsigned long end, pgprot_t newprot, int dirty_accountable)
{
pte_t *pte, oldpte;
spinlock_t *ptl;
@@ -48,6 +48,19 @@ static void change_pte_range(struct mm_struct *mm, pmd_t
*pmd,
oldpte = *pte;
if (pte_present(oldpte)) {
pte_t ptent;
+#ifdef CONFIG_AFFINITY_ON_NEXT_TOUCH
+ if (vma_migratable(vma)) {
+ struct page *page = vm_normal_page(vma,
addr,
+ oldpte);
+ /*
+ * By using affinity-on-next-touch the page
+ * fault handler will set the new page
+ * permissions!
+ */
+ if (page && PageUntouched(page))
+ continue;
+ }
+#endif
ptent = ptep_modify_prot_start(mm, addr, pte);
ptent = pte_modify(ptent, newprot);
@@ -78,9 +91,9 @@ static void change_pte_range(struct mm_struct *mm, pmd_t
*pmd,
pte_unmap_unlock(pte - 1, ptl);
}
-static inline void change_pmd_range(struct mm_struct *mm, pud_t *pud,
- unsigned long addr, unsigned long end, pgprot_t newprot,
- int dirty_accountable)
+static inline void change_pmd_range(struct vm_area_struct *vma,
+ struct mm_struct *mm, pud_t *pud, unsigned long addr,
+ unsigned long end, pgprot_t newprot, int dirty_accountable)
{
pmd_t *pmd;
unsigned long next;
@@ -90,13 +103,14 @@ static inline void change_pmd_range(struct mm_struct
*mm, pud_t *pud,
next = pmd_addr_end(addr, end);
if (pmd_none_or_clear_bad(pmd))
continue;
- change_pte_range(mm, pmd, addr, next, newprot,
dirty_accountable);
+ change_pte_range(vma, mm, pmd, addr, next, newprot,
+ dirty_accountable);
} while (pmd++, addr = next, addr != end);
}
-static inline void change_pud_range(struct mm_struct *mm, pgd_t *pgd,
- unsigned long addr, unsigned long end, pgprot_t newprot,
- int dirty_accountable)
+static inline void change_pud_range(struct vm_area_struct *vma,
+ struct mm_struct *mm, pgd_t *pgd, unsigned long addr,
+ unsigned long end, pgprot_t newprot, int dirty_accountable)
{
pud_t *pud;
unsigned long next;
@@ -106,7 +120,8 @@ static inline void change_pud_range(struct mm_struct
*mm, pgd_t *pgd,
next = pud_addr_end(addr, end);
if (pud_none_or_clear_bad(pud))
continue;
- change_pmd_range(mm, pud, addr, next, newprot,
dirty_accountable);
+ change_pmd_range(vma, mm, pud, addr, next, newprot,
+ dirty_accountable);
} while (pud++, addr = next, addr != end);
}
@@ -126,7 +141,7 @@ static void change_protection(struct vm_area_struct
*vma,
next = pgd_addr_end(addr, end);
if (pgd_none_or_clear_bad(pgd))
continue;
- change_pud_range(mm, pgd, addr, next, newprot,
dirty_accountable);
+ change_pud_range(vma, mm, pgd, addr, next, newprot,
dirty_accountable);
} while (pgd++, addr = next, addr != end);
flush_tlb_range(vma, start, end);
}
--
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