[PATCH 12/29] Abstract page table tear down

[Paul Davies <pauld@gelato.unsw.edu.au>]

PATCH 12
 * Moves the default page table tear down iterator from memory.c to
 pt_default.c

Signed-Off-By: Paul Davies <pauld@gelato.unsw.edu.au>

---

 memory.c     |  148 ----------------------------------------------------------
 pt-default.c |  149 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 149 insertions(+), 148 deletions(-)
Index: linux-2.6.20-rc1/mm/pt-default.c
===================================================================
--- linux-2.6.20-rc1.orig/mm/pt-default.c	2006-12-21 16:50:32.218023000 +1100
+++ linux-2.6.20-rc1/mm/pt-default.c	2006-12-21 17:34:52.106463000 +1100
@@ -139,3 +139,152 @@
 	return 0;
 }
 #endif /* __PAGETABLE_PMD_FOLDED */
+
+
+/*
+ * Note: this doesn't free the actual pages themselves. That
+ * has been handled earlier when unmapping all the memory regions.
+ */
+static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd)
+{
+	struct page *page = pmd_page(*pmd);
+	pmd_clear(pmd);
+	pte_lock_deinit(page);
+	pte_free_tlb(tlb, page);
+	dec_zone_page_state(page, NR_PAGETABLE);
+	tlb->mm->nr_ptes--;
+}
+
+static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
+				unsigned long addr, unsigned long end,
+				unsigned long floor, unsigned long ceiling)
+{
+	pmd_t *pmd;
+	unsigned long next;
+	unsigned long start;
+
+	start = addr;
+	pmd = pmd_offset(pud, addr);
+	do {
+		next = pmd_addr_end(addr, end);
+		if (pmd_none_or_clear_bad(pmd))
+			continue;
+		free_pte_range(tlb, pmd);
+	} while (pmd++, addr = next, addr != end);
+
+	start &= PUD_MASK;
+	if (start < floor)
+		return;
+	if (ceiling) {
+		ceiling &= PUD_MASK;
+		if (!ceiling)
+			return;
+	}
+	if (end - 1 > ceiling - 1)
+		return;
+
+	pmd = pmd_offset(pud, start);
+	pud_clear(pud);
+	pmd_free_tlb(tlb, pmd);
+}
+
+static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
+				unsigned long addr, unsigned long end,
+				unsigned long floor, unsigned long ceiling)
+{
+	pud_t *pud;
+	unsigned long next;
+	unsigned long start;
+
+	start = addr;
+	pud = pud_offset(pgd, addr);
+	do {
+		next = pud_addr_end(addr, end);
+		if (pud_none_or_clear_bad(pud))
+			continue;
+		free_pmd_range(tlb, pud, addr, next, floor, ceiling);
+	} while (pud++, addr = next, addr != end);
+
+	start &= PGDIR_MASK;
+	if (start < floor)
+		return;
+	if (ceiling) {
+		ceiling &= PGDIR_MASK;
+		if (!ceiling)
+			return;
+	}
+	if (end - 1 > ceiling - 1)
+		return;
+
+	pud = pud_offset(pgd, start);
+	pgd_clear(pgd);
+	pud_free_tlb(tlb, pud);
+}
+
+/*
+ * This function frees user-level page tables of a process.
+ *
+ * Must be called with pagetable lock held.
+ */
+void free_pgd_range(struct mmu_gather **tlb,
+			unsigned long addr, unsigned long end,
+			unsigned long floor, unsigned long ceiling)
+{
+	pgd_t *pgd;
+	unsigned long next;
+	unsigned long start;
+
+	/*
+	 * The next few lines have given us lots of grief...
+	 *
+	 * Why are we testing PMD* at this top level?  Because often
+	 * there will be no work to do at all, and we'd prefer not to
+	 * go all the way down to the bottom just to discover that.
+	 *
+	 * Why all these "- 1"s?  Because 0 represents both the bottom
+	 * of the address space and the top of it (using -1 for the
+	 * top wouldn't help much: the masks would do the wrong thing).
+	 * The rule is that addr 0 and floor 0 refer to the bottom of
+	 * the address space, but end 0 and ceiling 0 refer to the top
+	 * Comparisons need to use "end - 1" and "ceiling - 1" (though
+	 * that end 0 case should be mythical).
+	 *
+	 * Wherever addr is brought up or ceiling brought down, we must
+	 * be careful to reject "the opposite 0" before it confuses the
+	 * subsequent tests.  But what about where end is brought down
+	 * by PMD_SIZE below? no, end can't go down to 0 there.
+	 *
+	 * Whereas we round start (addr) and ceiling down, by different
+	 * masks at different levels, in order to test whether a table
+	 * now has no other vmas using it, so can be freed, we don't
+	 * bother to round floor or end up - the tests don't need that.
+	 */
+
+	addr &= PMD_MASK;
+	if (addr < floor) {
+		addr += PMD_SIZE;
+		if (!addr)
+			return;
+	}
+	if (ceiling) {
+		ceiling &= PMD_MASK;
+		if (!ceiling)
+			return;
+	}
+	if (end - 1 > ceiling - 1)
+		end -= PMD_SIZE;
+	if (addr > end - 1)
+		return;
+
+	start = addr;
+	pgd = pgd_offset((*tlb)->mm, addr);
+	do {
+		next = pgd_addr_end(addr, end);
+		if (pgd_none_or_clear_bad(pgd))
+			continue;
+		free_pud_range(*tlb, pgd, addr, next, floor, ceiling);
+	} while (pgd++, addr = next, addr != end);
+
+	if (!(*tlb)->fullmm)
+		flush_tlb_pgtables((*tlb)->mm, start, end);
+}
Index: linux-2.6.20-rc1/mm/memory.c
===================================================================
--- linux-2.6.20-rc1.orig/mm/memory.c	2006-12-21 17:23:31.325774000 +1100
+++ linux-2.6.20-rc1/mm/memory.c	2006-12-21 17:34:48.882463000 +1100
@@ -94,154 +94,6 @@
 }
 __setup("norandmaps", disable_randmaps);
 
-/*
- * Note: this doesn't free the actual pages themselves. That
- * has been handled earlier when unmapping all the memory regions.
- */
-static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd)
-{
-	struct page *page = pmd_page(*pmd);
-	pmd_clear(pmd);
-	pte_lock_deinit(page);
-	pte_free_tlb(tlb, page);
-	dec_zone_page_state(page, NR_PAGETABLE);
-	tlb->mm->nr_ptes--;
-}
-
-static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
-				unsigned long addr, unsigned long end,
-				unsigned long floor, unsigned long ceiling)
-{
-	pmd_t *pmd;
-	unsigned long next;
-	unsigned long start;
-
-	start = addr;
-	pmd = pmd_offset(pud, addr);
-	do {
-		next = pmd_addr_end(addr, end);
-		if (pmd_none_or_clear_bad(pmd))
-			continue;
-		free_pte_range(tlb, pmd);
-	} while (pmd++, addr = next, addr != end);
-
-	start &= PUD_MASK;
-	if (start < floor)
-		return;
-	if (ceiling) {
-		ceiling &= PUD_MASK;
-		if (!ceiling)
-			return;
-	}
-	if (end - 1 > ceiling - 1)
-		return;
-
-	pmd = pmd_offset(pud, start);
-	pud_clear(pud);
-	pmd_free_tlb(tlb, pmd);
-}
-
-static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
-				unsigned long addr, unsigned long end,
-				unsigned long floor, unsigned long ceiling)
-{
-	pud_t *pud;
-	unsigned long next;
-	unsigned long start;
-
-	start = addr;
-	pud = pud_offset(pgd, addr);
-	do {
-		next = pud_addr_end(addr, end);
-		if (pud_none_or_clear_bad(pud))
-			continue;
-		free_pmd_range(tlb, pud, addr, next, floor, ceiling);
-	} while (pud++, addr = next, addr != end);
-
-	start &= PGDIR_MASK;
-	if (start < floor)
-		return;
-	if (ceiling) {
-		ceiling &= PGDIR_MASK;
-		if (!ceiling)
-			return;
-	}
-	if (end - 1 > ceiling - 1)
-		return;
-
-	pud = pud_offset(pgd, start);
-	pgd_clear(pgd);
-	pud_free_tlb(tlb, pud);
-}
-
-/*
- * This function frees user-level page tables of a process.
- *
- * Must be called with pagetable lock held.
- */
-void free_pgd_range(struct mmu_gather **tlb,
-			unsigned long addr, unsigned long end,
-			unsigned long floor, unsigned long ceiling)
-{
-	pgd_t *pgd;
-	unsigned long next;
-	unsigned long start;
-
-	/*
-	 * The next few lines have given us lots of grief...
-	 *
-	 * Why are we testing PMD* at this top level?  Because often
-	 * there will be no work to do at all, and we'd prefer not to
-	 * go all the way down to the bottom just to discover that.
-	 *
-	 * Why all these "- 1"s?  Because 0 represents both the bottom
-	 * of the address space and the top of it (using -1 for the
-	 * top wouldn't help much: the masks would do the wrong thing).
-	 * The rule is that addr 0 and floor 0 refer to the bottom of
-	 * the address space, but end 0 and ceiling 0 refer to the top
-	 * Comparisons need to use "end - 1" and "ceiling - 1" (though
-	 * that end 0 case should be mythical).
-	 *
-	 * Wherever addr is brought up or ceiling brought down, we must
-	 * be careful to reject "the opposite 0" before it confuses the
-	 * subsequent tests.  But what about where end is brought down
-	 * by PMD_SIZE below? no, end can't go down to 0 there.
-	 *
-	 * Whereas we round start (addr) and ceiling down, by different
-	 * masks at different levels, in order to test whether a table
-	 * now has no other vmas using it, so can be freed, we don't
-	 * bother to round floor or end up - the tests don't need that.
-	 */
-
-	addr &= PMD_MASK;
-	if (addr < floor) {
-		addr += PMD_SIZE;
-		if (!addr)
-			return;
-	}
-	if (ceiling) {
-		ceiling &= PMD_MASK;
-		if (!ceiling)
-			return;
-	}
-	if (end - 1 > ceiling - 1)
-		end -= PMD_SIZE;
-	if (addr > end - 1)
-		return;
-
-	start = addr;
-	pgd = pgd_offset((*tlb)->mm, addr);
-	do {
-		next = pgd_addr_end(addr, end);
-		if (pgd_none_or_clear_bad(pgd))
-			continue;
-		free_pud_range(*tlb, pgd, addr, next, floor, ceiling);
-	} while (pgd++, addr = next, addr != end);
-
-	if (!(*tlb)->fullmm)
-		flush_tlb_pgtables((*tlb)->mm, start, end);
-}
-
 void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *vma,
 		unsigned long floor, unsigned long ceiling)
 {

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