1 files changed, 179 insertions, 60 deletions

diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c
index 6d94116fdea..c695943a513 100644
--- a/arch/powerpc/mm/pgtable.c
+++ b/arch/powerpc/mm/pgtable.c
@@ -1,5 +1,6 @@
 /*
  * This file contains common routines for dealing with free of page tables
+ * Along with common page table handling code
  *
  *  Derived from arch/powerpc/mm/tlb_64.c:
  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
@@ -21,97 +22,215 @@
  */
 
 #include <linux/kernel.h>
+#include <linux/gfp.h>
 #include <linux/mm.h>
-#include <linux/init.h>
 #include <linux/percpu.h>
 #include <linux/hardirq.h>
+#include <linux/hugetlb.h>
 #include <asm/pgalloc.h>
 #include <asm/tlbflush.h>
 #include <asm/tlb.h>
 
-static DEFINE_PER_CPU(struct pte_freelist_batch *, pte_freelist_cur);
-static unsigned long pte_freelist_forced_free;
-
-struct pte_freelist_batch
+static inline int is_exec_fault(void)
 {
-	struct rcu_head	rcu;
-	unsigned int	index;
-	pgtable_free_t	tables[0];
-};
-
-#define PTE_FREELIST_SIZE \
-	((PAGE_SIZE - sizeof(struct pte_freelist_batch)) \
-	  / sizeof(pgtable_free_t))
+	return current->thread.regs && TRAP(current->thread.regs) == 0x400;
+}
 
-static void pte_free_smp_sync(void *arg)
+/* We only try to do i/d cache coherency on stuff that looks like
+ * reasonably "normal" PTEs. We currently require a PTE to be present
+ * and we avoid _PAGE_SPECIAL and _PAGE_NO_CACHE. We also only do that
+ * on userspace PTEs
+ */
+static inline int pte_looks_normal(pte_t pte)
 {
-	/* Do nothing, just ensure we sync with all CPUs */
+	return (pte_val(pte) &
+	    (_PAGE_PRESENT | _PAGE_SPECIAL | _PAGE_NO_CACHE | _PAGE_USER)) ==
+	    (_PAGE_PRESENT | _PAGE_USER);
 }
 
-/* This is only called when we are critically out of memory
- * (and fail to get a page in pte_free_tlb).
- */
-static void pgtable_free_now(pgtable_free_t pgf)
+struct page * maybe_pte_to_page(pte_t pte)
 {
-	pte_freelist_forced_free++;
+	unsigned long pfn = pte_pfn(pte);
+	struct page *page;
+
+	if (unlikely(!pfn_valid(pfn)))
+		return NULL;
+	page = pfn_to_page(pfn);
+	if (PageReserved(page))
+		return NULL;
+	return page;
+}
 
-	smp_call_function(pte_free_smp_sync, NULL, 1);
+#if defined(CONFIG_PPC_STD_MMU) || _PAGE_EXEC == 0
+
+/* Server-style MMU handles coherency when hashing if HW exec permission
+ * is supposed per page (currently 64-bit only). If not, then, we always
+ * flush the cache for valid PTEs in set_pte. Embedded CPU without HW exec
+ * support falls into the same category.
+ */
 
-	pgtable_free(pgf);
+static pte_t set_pte_filter(pte_t pte)
+{
+	pte = __pte(pte_val(pte) & ~_PAGE_HPTEFLAGS);
+	if (pte_looks_normal(pte) && !(cpu_has_feature(CPU_FTR_COHERENT_ICACHE) ||
+				       cpu_has_feature(CPU_FTR_NOEXECUTE))) {
+		struct page *pg = maybe_pte_to_page(pte);
+		if (!pg)
+			return pte;
+		if (!test_bit(PG_arch_1, &pg->flags)) {
+			flush_dcache_icache_page(pg);
+			set_bit(PG_arch_1, &pg->flags);
+		}
+	}
+	return pte;
 }
 
-static void pte_free_rcu_callback(struct rcu_head *head)
+static pte_t set_access_flags_filter(pte_t pte, struct vm_area_struct *vma,
+				     int dirty)
 {
-	struct pte_freelist_batch *batch =
-		container_of(head, struct pte_freelist_batch, rcu);
-	unsigned int i;
+	return pte;
+}
 
-	for (i = 0; i < batch->index; i++)
-		pgtable_free(batch->tables[i]);
+#else /* defined(CONFIG_PPC_STD_MMU) || _PAGE_EXEC == 0 */
+
+/* Embedded type MMU with HW exec support. This is a bit more complicated
+ * as we don't have two bits to spare for _PAGE_EXEC and _PAGE_HWEXEC so
+ * instead we "filter out" the exec permission for non clean pages.
+ */
+static pte_t set_pte_filter(pte_t pte)
+{
+	struct page *pg;
+
+	/* No exec permission in the first place, move on */
+	if (!(pte_val(pte) & _PAGE_EXEC) || !pte_looks_normal(pte))
+		return pte;
+
+	/* If you set _PAGE_EXEC on weird pages you're on your own */
+	pg = maybe_pte_to_page(pte);
+	if (unlikely(!pg))
+		return pte;
+
+	/* If the page clean, we move on */
+	if (test_bit(PG_arch_1, &pg->flags))
+		return pte;
+
+	/* If it's an exec fault, we flush the cache and make it clean */
+	if (is_exec_fault()) {
+		flush_dcache_icache_page(pg);
+		set_bit(PG_arch_1, &pg->flags);
+		return pte;
+	}
 
-	free_page((unsigned long)batch);
+	/* Else, we filter out _PAGE_EXEC */
+	return __pte(pte_val(pte) & ~_PAGE_EXEC);
 }
 
-static void pte_free_submit(struct pte_freelist_batch *batch)
+static pte_t set_access_flags_filter(pte_t pte, struct vm_area_struct *vma,
+				     int dirty)
 {
-	INIT_RCU_HEAD(&batch->rcu);
-	call_rcu(&batch->rcu, pte_free_rcu_callback);
+	struct page *pg;
+
+	/* So here, we only care about exec faults, as we use them
+	 * to recover lost _PAGE_EXEC and perform I$/D$ coherency
+	 * if necessary. Also if _PAGE_EXEC is already set, same deal,
+	 * we just bail out
+	 */
+	if (dirty || (pte_val(pte) & _PAGE_EXEC) || !is_exec_fault())
+		return pte;
+
+#ifdef CONFIG_DEBUG_VM
+	/* So this is an exec fault, _PAGE_EXEC is not set. If it was
+	 * an error we would have bailed out earlier in do_page_fault()
+	 * but let's make sure of it
+	 */
+	if (WARN_ON(!(vma->vm_flags & VM_EXEC)))
+		return pte;
+#endif /* CONFIG_DEBUG_VM */
+
+	/* If you set _PAGE_EXEC on weird pages you're on your own */
+	pg = maybe_pte_to_page(pte);
+	if (unlikely(!pg))
+		goto bail;
+
+	/* If the page is already clean, we move on */
+	if (test_bit(PG_arch_1, &pg->flags))
+		goto bail;
+
+	/* Clean the page and set PG_arch_1 */
+	flush_dcache_icache_page(pg);
+	set_bit(PG_arch_1, &pg->flags);
+
+ bail:
+	return __pte(pte_val(pte) | _PAGE_EXEC);
 }
 
-void pgtable_free_tlb(struct mmu_gather *tlb, pgtable_free_t pgf)
-{
-	/* This is safe since tlb_gather_mmu has disabled preemption */
-        cpumask_t local_cpumask = cpumask_of_cpu(smp_processor_id());
-	struct pte_freelist_batch **batchp = &__get_cpu_var(pte_freelist_cur);
+#endif /* !(defined(CONFIG_PPC_STD_MMU) || _PAGE_EXEC == 0) */
 
-	if (atomic_read(&tlb->mm->mm_users) < 2 ||
-	    cpus_equal(tlb->mm->cpu_vm_mask, local_cpumask)) {
-		pgtable_free(pgf);
-		return;
-	}
+/*
+ * set_pte stores a linux PTE into the linux page table.
+ */
+void set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
+		pte_t pte)
+{
+#ifdef CONFIG_DEBUG_VM
+	WARN_ON(pte_val(*ptep) & _PAGE_PRESENT);
+#endif
+	/* Note: mm->context.id might not yet have been assigned as
+	 * this context might not have been activated yet when this
+	 * is called.
+	 */
+	pte = set_pte_filter(pte);
+
+	/* Perform the setting of the PTE */
+	__set_pte_at(mm, addr, ptep, pte, 0);
+}
 
-	if (*batchp == NULL) {
-		*batchp = (struct pte_freelist_batch *)__get_free_page(GFP_ATOMIC);
-		if (*batchp == NULL) {
-			pgtable_free_now(pgf);
-			return;
-		}
-		(*batchp)->index = 0;
-	}
-	(*batchp)->tables[(*batchp)->index++] = pgf;
-	if ((*batchp)->index == PTE_FREELIST_SIZE) {
-		pte_free_submit(*batchp);
-		*batchp = NULL;
+/*
+ * This is called when relaxing access to a PTE. It's also called in the page
+ * fault path when we don't hit any of the major fault cases, ie, a minor
+ * update of _PAGE_ACCESSED, _PAGE_DIRTY, etc... The generic code will have
+ * handled those two for us, we additionally deal with missing execute
+ * permission here on some processors
+ */
+int ptep_set_access_flags(struct vm_area_struct *vma, unsigned long address,
+			  pte_t *ptep, pte_t entry, int dirty)
+{
+	int changed;
+	entry = set_access_flags_filter(entry, vma, dirty);
+	changed = !pte_same(*(ptep), entry);
+	if (changed) {
+		if (!is_vm_hugetlb_page(vma))
+			assert_pte_locked(vma->vm_mm, address);
+		__ptep_set_access_flags(ptep, entry);
+		flush_tlb_page_nohash(vma, address);
 	}
+	return changed;
 }
 
-void pte_free_finish(void)
+#ifdef CONFIG_DEBUG_VM
+void assert_pte_locked(struct mm_struct *mm, unsigned long addr)
 {
-	/* This is safe since tlb_gather_mmu has disabled preemption */
-	struct pte_freelist_batch **batchp = &__get_cpu_var(pte_freelist_cur);
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
 
-	if (*batchp == NULL)
+	if (mm == &init_mm)
+		return;
+	pgd = mm->pgd + pgd_index(addr);
+	BUG_ON(pgd_none(*pgd));
+	pud = pud_offset(pgd, addr);
+	BUG_ON(pud_none(*pud));
+	pmd = pmd_offset(pud, addr);
+	/*
+	 * khugepaged to collapse normal pages to hugepage, first set
+	 * pmd to none to force page fault/gup to take mmap_sem. After
+	 * pmd is set to none, we do a pte_clear which does this assertion
+	 * so if we find pmd none, return.
+	 */
+	if (pmd_none(*pmd))
 		return;
-	pte_free_submit(*batchp);
-	*batchp = NULL;
+	BUG_ON(!pmd_present(*pmd));
+	assert_spin_locked(pte_lockptr(mm, pmd));
 }
+#endif /* CONFIG_DEBUG_VM */
+