1 files changed, 60 insertions, 5 deletions

diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index d37f29376b0c..9b5f7d7049d0 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -194,11 +194,30 @@ static void __init kernel_physical_mapping_init(pgd_t *pgd_base,
         pgd_t *pgd;
         pmd_t *pmd;
         pte_t *pte;
-        unsigned pages_2m = 0, pages_4k = 0;
+        unsigned pages_2m, pages_4k;
+        int mapping_iter;
+
+        /*
+         * First iteration will setup identity mapping using large/small pages
+         * based on use_pse, with other attributes same as set by
+         * the early code in head_32.S
+         *
+         * Second iteration will setup the appropriate attributes (NX, GLOBAL..)
+         * as desired for the kernel identity mapping.
+         *
+         * This two pass mechanism conforms to the TLB app note which says:
+         *
+         *     "Software should not write to a paging-structure entry in a way
+         *      that would change, for any linear address, both the page size
+         *      and either the page frame or attributes."
+         */
+        mapping_iter = 1;
 
         if (!cpu_has_pse)
                 use_pse = 0;
 
+repeat:
+        pages_2m = pages_4k = 0;
         pfn = start_pfn;
         pgd_idx = pgd_index((pfn<<PAGE_SHIFT) + PAGE_OFFSET);
         pgd = pgd_base + pgd_idx;
@@ -224,6 +243,13 @@ static void __init kernel_physical_mapping_init(pgd_t *pgd_base,
                         if (use_pse) {
                                 unsigned int addr2;
                                 pgprot_t prot = PAGE_KERNEL_LARGE;
+                                /*
+                                 * first pass will use the same initial
+                                 * identity mapping attribute + _PAGE_PSE.
+                                 */
+                                pgprot_t init_prot =
+                                        __pgprot(PTE_IDENT_ATTR |
+                                                 _PAGE_PSE);
 
                                 addr2 = (pfn + PTRS_PER_PTE-1) * PAGE_SIZE +
                                         PAGE_OFFSET + PAGE_SIZE-1;
@@ -233,7 +259,10 @@ static void __init kernel_physical_mapping_init(pgd_t *pgd_base,
                                         prot = PAGE_KERNEL_LARGE_EXEC;
 
                                 pages_2m++;
-                                set_pmd(pmd, pfn_pmd(pfn, prot));
+                                if (mapping_iter == 1)
+                                        set_pmd(pmd, pfn_pmd(pfn, init_prot));
+                                else
+                                        set_pmd(pmd, pfn_pmd(pfn, prot));
 
                                 pfn += PTRS_PER_PTE;
                                 continue;
@@ -245,17 +274,43 @@ static void __init kernel_physical_mapping_init(pgd_t *pgd_base,
                         for (; pte_ofs < PTRS_PER_PTE && pfn < end_pfn;
                              pte++, pfn++, pte_ofs++, addr += PAGE_SIZE) {
                                 pgprot_t prot = PAGE_KERNEL;
+                                /*
+                                 * first pass will use the same initial
+                                 * identity mapping attribute.
+                                 */
+                                pgprot_t init_prot = __pgprot(PTE_IDENT_ATTR);
 
                                 if (is_kernel_text(addr))
                                         prot = PAGE_KERNEL_EXEC;
 
                                 pages_4k++;
-                                set_pte(pte, pfn_pte(pfn, prot));
+                                if (mapping_iter == 1)
+                                        set_pte(pte, pfn_pte(pfn, init_prot));
+                                else
+                                        set_pte(pte, pfn_pte(pfn, prot));
                         }
                 }
         }
-        update_page_count(PG_LEVEL_2M, pages_2m);
-        update_page_count(PG_LEVEL_4K, pages_4k);
+        if (mapping_iter == 1) {
+                /*
+                 * update direct mapping page count only in the first
+                 * iteration.
+                 */
+                update_page_count(PG_LEVEL_2M, pages_2m);
+                update_page_count(PG_LEVEL_4K, pages_4k);
+
+                /*
+                 * local global flush tlb, which will flush the previous
+                 * mappings present in both small and large page TLB's.
+                 */
+                __flush_tlb_all();
+
+                /*
+                 * Second iteration will set the actual desired PTE attributes.
+                 */
+                mapping_iter = 2;
+                goto repeat;
+        }
 }
 
 /*