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authorBorislav Petkov <bp@suse.de>2013-10-31 16:25:06 (GMT)
committerMatt Fleming <matt.fleming@intel.com>2013-11-02 11:09:31 (GMT)
commit52a628fb454d13d944bb3c8a89a314cc3affa417 (patch)
tree413a3adec4856a0ab4212a28d541dc8b54f5c362 /arch/x86/mm
parent0bb8aeee7b73b21e09d3ea12f2120d974f70b669 (diff)
x86/mm/pageattr: Add last levels of error path
We try to free the pagetable pages once we've unmapped our portion. Signed-off-by: Borislav Petkov <bp@suse.de> Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Diffstat (limited to 'arch/x86/mm')
-rw-r--r--arch/x86/mm/pageattr.c94
1 files changed, 93 insertions, 1 deletions
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 1cbdbbc..db8ace2 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -666,7 +666,99 @@ static int split_large_page(pte_t *kpte, unsigned long address)
return 0;
}
-#define unmap_pmd_range(pud, start, pre_end) do {} while (0)
+static bool try_to_free_pte_page(pte_t *pte)
+{
+ int i;
+
+ for (i = 0; i < PTRS_PER_PTE; i++)
+ if (!pte_none(pte[i]))
+ return false;
+
+ free_page((unsigned long)pte);
+ return true;
+}
+
+static bool try_to_free_pmd_page(pmd_t *pmd)
+{
+ int i;
+
+ for (i = 0; i < PTRS_PER_PMD; i++)
+ if (!pmd_none(pmd[i]))
+ return false;
+
+ free_page((unsigned long)pmd);
+ return true;
+}
+
+static bool unmap_pte_range(pmd_t *pmd, unsigned long start, unsigned long end)
+{
+ pte_t *pte = pte_offset_kernel(pmd, start);
+
+ while (start < end) {
+ set_pte(pte, __pte(0));
+
+ start += PAGE_SIZE;
+ pte++;
+ }
+
+ if (try_to_free_pte_page((pte_t *)pmd_page_vaddr(*pmd))) {
+ pmd_clear(pmd);
+ return true;
+ }
+ return false;
+}
+
+static void __unmap_pmd_range(pud_t *pud, pmd_t *pmd,
+ unsigned long start, unsigned long end)
+{
+ if (unmap_pte_range(pmd, start, end))
+ if (try_to_free_pmd_page((pmd_t *)pud_page_vaddr(*pud)))
+ pud_clear(pud);
+}
+
+static void unmap_pmd_range(pud_t *pud, unsigned long start, unsigned long end)
+{
+ pmd_t *pmd = pmd_offset(pud, start);
+
+ /*
+ * Not on a 2MB page boundary?
+ */
+ if (start & (PMD_SIZE - 1)) {
+ unsigned long next_page = (start + PMD_SIZE) & PMD_MASK;
+ unsigned long pre_end = min_t(unsigned long, end, next_page);
+
+ __unmap_pmd_range(pud, pmd, start, pre_end);
+
+ start = pre_end;
+ pmd++;
+ }
+
+ /*
+ * Try to unmap in 2M chunks.
+ */
+ while (end - start >= PMD_SIZE) {
+ if (pmd_large(*pmd))
+ pmd_clear(pmd);
+ else
+ __unmap_pmd_range(pud, pmd, start, start + PMD_SIZE);
+
+ start += PMD_SIZE;
+ pmd++;
+ }
+
+ /*
+ * 4K leftovers?
+ */
+ if (start < end)
+ return __unmap_pmd_range(pud, pmd, start, end);
+
+ /*
+ * Try again to free the PMD page if haven't succeeded above.
+ */
+ if (!pud_none(*pud))
+ if (try_to_free_pmd_page((pmd_t *)pud_page_vaddr(*pud)))
+ pud_clear(pud);
+}
static void unmap_pud_range(pgd_t *pgd, unsigned long start, unsigned long end)
{

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