source: trunk/packages/xen-3.1/xen-3.1/patches/linux-2.6.18/pmd-shared.patch @ 34

arch/i386/mm/pageattr.c

@@ -84 +84 @@
         unsigned long flags;
 
         set_pte_atomic(kpte, pte);      /* change init_mm */
-        if (PTRS_PER_PMD > 1)
+        if (HAVE_SHARED_KERNEL_PMD)
                 return;
 
         spin_lock_irqsave(&pgd_lock, flags);

arch/i386/mm/pgtable.c

@@ -214 +214 @@
                 spin_lock_irqsave(&pgd_lock, flags);
         }
 
-        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 || HAVE_SHARED_KERNEL_PMD)
+                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;
 
@@ -248 +249 @@
                         goto out_oom;
                 set_pgd(&pgd[i], __pgd(1 + __pa(pmd)));
         }
+
+        if (!HAVE_SHARED_KERNEL_PMD) {
+                unsigned long flags;
+
+                for (i = USER_PTRS_PER_PGD; i < PTRS_PER_PGD; i++) {
+                        pmd_t *pmd = kmem_cache_alloc(pmd_cache, GFP_KERNEL);
+                        if (!pmd)
+                                goto out_oom;
+                        set_pgd(&pgd[USER_PTRS_PER_PGD], __pgd(1 + __pa(pmd)));
+                }
+
+                spin_lock_irqsave(&pgd_lock, flags);
+                for (i = USER_PTRS_PER_PGD; i < PTRS_PER_PGD; i++) {
+                        unsigned long v = (unsigned long)i << PGDIR_SHIFT;
+                        pgd_t *kpgd = pgd_offset_k(v);
+                        pud_t *kpud = pud_offset(kpgd, v);
+                        pmd_t *kpmd = pmd_offset(kpud, v);
+                        pmd_t *pmd = (void *)__va(pgd_val(pgd[i])-1);
+                        memcpy(pmd, kpmd, PAGE_SIZE);
+                }
+                pgd_list_add(pgd);
+                spin_unlock_irqrestore(&pgd_lock, flags);
+        }
+
         return pgd;
 
 out_oom:
@@ -262 +287 @@
         int i;
 
         /* 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)
-                        kmem_cache_free(pmd_cache, (void *)__va(pgd_val(pgd[i])-1));
+        if (PTRS_PER_PMD > 1) {
+                for (i = 0; i < USER_PTRS_PER_PGD; ++i) {
+                        pmd_t *pmd = (void *)__va(pgd_val(pgd[i])-1);
+                        kmem_cache_free(pmd_cache, pmd);
+                }
+                if (!HAVE_SHARED_KERNEL_PMD) {
+                        unsigned long flags;
+                        spin_lock_irqsave(&pgd_lock, flags);
+                        pgd_list_del(pgd);
+                        spin_unlock_irqrestore(&pgd_lock, flags);
+                        for (i = USER_PTRS_PER_PGD; i < PTRS_PER_PGD; i++) {
+                                pmd_t *pmd = (void *)__va(pgd_val(pgd[i])-1);
+                                memset(pmd, 0, PTRS_PER_PMD*sizeof(pmd_t));
+                                kmem_cache_free(pmd_cache, pmd);
+                        }
+                }
+        }
         /* in the non-PAE case, free_pgtables() clears user pgd entries */
         kmem_cache_free(pgd_cache, pgd);
 }

include/asm-i386/pgtable-2level-defs.h

@@ -1 +1 @@
 #ifndef _I386_PGTABLE_2LEVEL_DEFS_H
 #define _I386_PGTABLE_2LEVEL_DEFS_H
 
+#define HAVE_SHARED_KERNEL_PMD 0
+
 /*
  * traditional i386 two-level paging structure:
  */

include/asm-i386/pgtable-3level-defs.h

@@ -1 +1 @@
 #ifndef _I386_PGTABLE_3LEVEL_DEFS_H
 #define _I386_PGTABLE_3LEVEL_DEFS_H
 
+#define HAVE_SHARED_KERNEL_PMD 1
+
 /*
  * PGDIR_SHIFT determines what a top-level page table entry can map
  */