1 files changed, 70 insertions, 18 deletions

diff --git a/arch/i386/mm/pgtable.c b/arch/i386/mm/pgtable.c
index 99c09edc3dbb..9a96c1647428 100644
--- a/arch/i386/mm/pgtable.c
+++ b/arch/i386/mm/pgtable.c
@@ -232,42 +232,92 @@ static inline void pgd_list_del(pgd_t *pgd)
                 set_page_private(next, (unsigned long)pprev);
 }
 
+#if (PTRS_PER_PMD == 1)
+/* Non-PAE pgd constructor */
 void pgd_ctor(void *pgd, struct kmem_cache *cache, unsigned long unused)
 {
         unsigned long flags;
 
-        if (PTRS_PER_PMD == 1) {
-                memset(pgd, 0, USER_PTRS_PER_PGD*sizeof(pgd_t));
-                spin_lock_irqsave(&pgd_lock, flags);
-        }
+        /* !PAE, no pagetable sharing */
+        memset(pgd, 0, USER_PTRS_PER_PGD*sizeof(pgd_t));
+
+        spin_lock_irqsave(&pgd_lock, flags);
 
+        /* must happen under lock */
         clone_pgd_range((pgd_t *)pgd + USER_PTRS_PER_PGD,
                         swapper_pg_dir + USER_PTRS_PER_PGD,
                         KERNEL_PGD_PTRS);
-
-        if (PTRS_PER_PMD > 1)
-                return;
-
-        /* must happen under lock */
         paravirt_alloc_pd_clone(__pa(pgd) >> PAGE_SHIFT,
-                        __pa(swapper_pg_dir) >> PAGE_SHIFT,
-                        USER_PTRS_PER_PGD, PTRS_PER_PGD - USER_PTRS_PER_PGD);
-
+                                __pa(swapper_pg_dir) >> PAGE_SHIFT,
+                                USER_PTRS_PER_PGD,
+                                KERNEL_PGD_PTRS);
         pgd_list_add(pgd);
         spin_unlock_irqrestore(&pgd_lock, flags);
 }
+#else  /* PTRS_PER_PMD > 1 */
+/* PAE pgd constructor */
+void pgd_ctor(void *pgd, struct kmem_cache *cache, unsigned long unused)
+{
+        /* PAE, kernel PMD may be shared */
+
+        if (SHARED_KERNEL_PMD) {
+                clone_pgd_range((pgd_t *)pgd + USER_PTRS_PER_PGD,
+                                swapper_pg_dir + USER_PTRS_PER_PGD,
+                                KERNEL_PGD_PTRS);
+        } else {
+                unsigned long flags;
+
+                memset(pgd, 0, USER_PTRS_PER_PGD*sizeof(pgd_t));
+                spin_lock_irqsave(&pgd_lock, flags);
+                pgd_list_add(pgd);
+                spin_unlock_irqrestore(&pgd_lock, flags);
+        }
+}
+#endif  /* PTRS_PER_PMD */
 
-/* never called when PTRS_PER_PMD > 1 */
 void pgd_dtor(void *pgd, struct kmem_cache *cache, unsigned long unused)
 {
         unsigned long flags; /* can be called from interrupt context */
 
+        BUG_ON(SHARED_KERNEL_PMD);
+
         paravirt_release_pd(__pa(pgd) >> PAGE_SHIFT);
         spin_lock_irqsave(&pgd_lock, flags);
         pgd_list_del(pgd);
         spin_unlock_irqrestore(&pgd_lock, flags);
 }
 
+#define UNSHARED_PTRS_PER_PGD                           \
+        (SHARED_KERNEL_PMD ? USER_PTRS_PER_PGD : PTRS_PER_PGD)
+
+/* If we allocate a pmd for part of the kernel address space, then
+   make sure its initialized with the appropriate kernel mappings.
+   Otherwise use a cached zeroed pmd.  */
+static pmd_t *pmd_cache_alloc(int idx)
+{
+        pmd_t *pmd;
+
+        if (idx >= USER_PTRS_PER_PGD) {
+                pmd = (pmd_t *)__get_free_page(GFP_KERNEL);
+
+                if (pmd)
+                        memcpy(pmd,
+                               (void *)pgd_page_vaddr(swapper_pg_dir[idx]),
+                               sizeof(pmd_t) * PTRS_PER_PMD);
+        } else
+                pmd = kmem_cache_alloc(pmd_cache, GFP_KERNEL);
+
+        return pmd;
+}
+
+static void pmd_cache_free(pmd_t *pmd, int idx)
+{
+        if (idx >= USER_PTRS_PER_PGD)
+                free_page((unsigned long)pmd);
+        else
+                kmem_cache_free(pmd_cache, pmd);
+}
+
 pgd_t *pgd_alloc(struct mm_struct *mm)
 {
         int i;
@@ -276,10 +326,12 @@ pgd_t *pgd_alloc(struct mm_struct *mm)
         if (PTRS_PER_PMD == 1 || !pgd)
                 return pgd;
 
-        for (i = 0; i < USER_PTRS_PER_PGD; ++i) {
-                pmd_t *pmd = kmem_cache_alloc(pmd_cache, GFP_KERNEL);
+        for (i = 0; i < UNSHARED_PTRS_PER_PGD; ++i) {
+                pmd_t *pmd = pmd_cache_alloc(i);
+
                 if (!pmd)
                         goto out_oom;
+
                 paravirt_alloc_pd(__pa(pmd) >> PAGE_SHIFT);
                 set_pgd(&pgd[i], __pgd(1 + __pa(pmd)));
         }
@@ -290,7 +342,7 @@ out_oom:
                 pgd_t pgdent = pgd[i];
                 void* pmd = (void *)__va(pgd_val(pgdent)-1);
                 paravirt_release_pd(__pa(pmd) >> PAGE_SHIFT);
-                kmem_cache_free(pmd_cache, pmd);
+                pmd_cache_free(pmd, i);
         }
         kmem_cache_free(pgd_cache, pgd);
         return NULL;
@@ -302,11 +354,11 @@ void pgd_free(pgd_t *pgd)
 
         /* in the PAE case user pgd entries are overwritten before usage */
         if (PTRS_PER_PMD > 1)
-                for (i = 0; i < USER_PTRS_PER_PGD; ++i) {
+                for (i = 0; i < UNSHARED_PTRS_PER_PGD; ++i) {
                         pgd_t pgdent = pgd[i];
                         void* pmd = (void *)__va(pgd_val(pgdent)-1);
                         paravirt_release_pd(__pa(pmd) >> PAGE_SHIFT);
-                        kmem_cache_free(pmd_cache, pmd);
+                        pmd_cache_free(pmd, i);
                 }
         /* in the non-PAE case, free_pgtables() clears user pgd entries */
         kmem_cache_free(pgd_cache, pgd);