x86, cpa: make the kernel physical mapping initialization a two pass sequence

[linux-2.6-omap-h63xx.git] / arch / x86 / mm / init_32.c

diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index d37f29376b0ce455ae3907051a58779f4b995a25..9b5f7d7049d044c78f017f1f33377ac5db4caed7 100644 (file)
--- 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;
+       }
 }
 
 /*