1 files changed, 128 insertions, 51 deletions

diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c
index 627767d6169b..83f1551ec2c9 100644
--- a/arch/powerpc/mm/pgtable.c
+++ b/arch/powerpc/mm/pgtable.c
@@ -30,6 +30,16 @@
 #include <asm/tlbflush.h>
 #include <asm/tlb.h>
 
+DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
+
+#ifdef CONFIG_SMP
+
+/*
+ * Handle batching of page table freeing on SMP. Page tables are
+ * queued up and send to be freed later by RCU in order to avoid
+ * freeing a page table page that is being walked without locks
+ */
+
 static DEFINE_PER_CPU(struct pte_freelist_batch *, pte_freelist_cur);
 static unsigned long pte_freelist_forced_free;
 
@@ -116,27 +126,7 @@ void pte_free_finish(void)
         *batchp = NULL;
 }
 
-/*
- * Handle i/d cache flushing, called from set_pte_at() or ptep_set_access_flags()
- */
-static pte_t do_dcache_icache_coherency(pte_t pte)
-{
-        unsigned long pfn = pte_pfn(pte);
-        struct page *page;
-
-        if (unlikely(!pfn_valid(pfn)))
-                return pte;
-        page = pfn_to_page(pfn);
-
-        if (!PageReserved(page) && !test_bit(PG_arch_1, &page->flags)) {
-                pr_devel("do_dcache_icache_coherency... flushing\n");
-                flush_dcache_icache_page(page);
-                set_bit(PG_arch_1, &page->flags);
-        }
-        else
-                pr_devel("do_dcache_icache_coherency... already clean\n");
-        return __pte(pte_val(pte) | _PAGE_HWEXEC);
-}
+#endif /* CONFIG_SMP */
 
 static inline int is_exec_fault(void)
 {
@@ -145,49 +135,139 @@ static inline int is_exec_fault(void)
 
 /* 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
+ * 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)
 {
         return (pte_val(pte) &
-                (_PAGE_PRESENT | _PAGE_SPECIAL | _PAGE_NO_CACHE)) ==
-                (_PAGE_PRESENT);
+            (_PAGE_PRESENT | _PAGE_SPECIAL | _PAGE_NO_CACHE | _PAGE_USER)) ==
+            (_PAGE_PRESENT | _PAGE_USER);
 }
 
-#if defined(CONFIG_PPC_STD_MMU)
+struct page * maybe_pte_to_page(pte_t pte)
+{
+        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;
+}
+
+#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). Else, we always flush
- * valid PTEs in set_pte.
+ * 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.
  */
-static inline int pte_need_exec_flush(pte_t pte, int set_pte)
+
+static pte_t set_pte_filter(pte_t pte)
 {
-        return set_pte && pte_looks_normal(pte) &&
-                !(cpu_has_feature(CPU_FTR_COHERENT_ICACHE) ||
-                  cpu_has_feature(CPU_FTR_NOEXECUTE));
+        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;
 }
-#elif _PAGE_HWEXEC == 0
-/* Embedded type MMU without HW exec support (8xx only so far), we flush
- * the cache for any present PTE
- */
-static inline int pte_need_exec_flush(pte_t pte, int set_pte)
+
+static pte_t set_access_flags_filter(pte_t pte, struct vm_area_struct *vma,
+                                     int dirty)
 {
-        return set_pte && pte_looks_normal(pte);
+        return pte;
 }
-#else
-/* Other embedded CPUs with HW exec support per-page, we flush on exec
- * fault if HWEXEC is not set
+
+#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 inline int pte_need_exec_flush(pte_t pte, int set_pte)
+static pte_t set_pte_filter(pte_t pte)
 {
-        return pte_looks_normal(pte) && is_exec_fault() &&
-                !(pte_val(pte) & _PAGE_HWEXEC);
+        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;
+        }
+
+        /* Else, we filter out _PAGE_EXEC */
+        return __pte(pte_val(pte) & ~_PAGE_EXEC);
 }
-#endif
+
+static pte_t set_access_flags_filter(pte_t pte, struct vm_area_struct *vma,
+                                     int dirty)
+{
+        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);
+}
+
+#endif /* !(defined(CONFIG_PPC_STD_MMU) || _PAGE_EXEC == 0) */
 
 /*
  * 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)
+void set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
+                pte_t pte)
 {
 #ifdef CONFIG_DEBUG_VM
         WARN_ON(pte_present(*ptep));
@@ -196,9 +276,7 @@ void set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t pte
          * this context might not have been activated yet when this
          * is called.
          */
-        pte = __pte(pte_val(pte) & ~_PAGE_HPTEFLAGS);
-        if (pte_need_exec_flush(pte, 1))
-                pte = do_dcache_icache_coherency(pte);
+        pte = set_pte_filter(pte);
 
         /* Perform the setting of the PTE */
         __set_pte_at(mm, addr, ptep, pte, 0);
@@ -215,8 +293,7 @@ int ptep_set_access_flags(struct vm_area_struct *vma, unsigned long address,
                           pte_t *ptep, pte_t entry, int dirty)
 {
         int changed;
-        if (!dirty && pte_need_exec_flush(entry, 0))
-                entry = do_dcache_icache_coherency(entry);
+        entry = set_access_flags_filter(entry, vma, dirty);
         changed = !pte_same(*(ptep), entry);
         if (changed) {
                 if (!(vma->vm_flags & VM_HUGETLB))
@@ -242,7 +319,7 @@ void assert_pte_locked(struct mm_struct *mm, unsigned long addr)
         BUG_ON(pud_none(*pud));
         pmd = pmd_offset(pud, addr);
         BUG_ON(!pmd_present(*pmd));
-        BUG_ON(!spin_is_locked(pte_lockptr(mm, pmd)));
+        assert_spin_locked(pte_lockptr(mm, pmd));
 }
 #endif /* CONFIG_DEBUG_VM */