x86: 64-bit, add the new split_large_page() function

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/arch/x86/mm/pageattr_64.c b/arch/x86/mm/pageattr_64.c
index 190d4d37bc2f3e590dffb7632b75c31f7cf3d6c5..139795029fb631cf3f907d39cbc0349e08b1df6b 100644 (file)
--- a/arch/x86/mm/pageattr_64.c
+++ b/arch/x86/mm/pageattr_64.c
@@ -45,34 +45,91 @@ pte_t *lookup_address(unsigned long address, int *level)
        return pte_offset_kernel(pmd, address);
 }
 
-static struct page *
-split_large_page(unsigned long address, pgprot_t ref_prot)
+static void __set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte)
 {
+       /* change init_mm */
+       set_pte_atomic(kpte, pte);
+#ifdef CONFIG_X86_32
+       if (SHARED_KERNEL_PMD)
+               return;
+       {
+               struct page *page;
+
+               for (page = pgd_list; page; page = (struct page *)page->index) {
+                       pgd_t *pgd;
+                       pud_t *pud;
+                       pmd_t *pmd;
+
+                       pgd = (pgd_t *)page_address(page) + pgd_index(address);
+                       pud = pud_offset(pgd, address);
+                       pmd = pmd_offset(pud, address);
+                       set_pte_atomic((pte_t *)pmd, pte);
+               }
+       }
+#endif
+}
+
+static int split_large_page(pte_t *kpte, unsigned long address)
+{
+       pgprot_t ref_prot = pte_pgprot(pte_clrhuge(*kpte));
+       gfp_t gfp_flags = GFP_KERNEL;
+       unsigned long flags;
        unsigned long addr;
+       pte_t *pbase, *tmp;
        struct page *base;
-       pte_t *pbase;
-       int i;
+       int i, level;
+
 
-       base = alloc_pages(GFP_KERNEL, 0);
+#ifdef CONFIG_DEBUG_PAGEALLOC
+       gfp_flags = GFP_ATOMIC;
+#endif
+       base = alloc_pages(gfp_flags, 0);
        if (!base)
-               return NULL;
+               return -ENOMEM;
+
+       spin_lock_irqsave(&pgd_lock, flags);
+       /*
+        * Check for races, another CPU might have split this page
+        * up for us already:
+        */
+       tmp = lookup_address(address, &level);
+       if (tmp != kpte) {
+               WARN_ON_ONCE(1);
+               goto out_unlock;
+       }
 
        address = __pa(address);
        addr = address & LARGE_PAGE_MASK;
        pbase = (pte_t *)page_address(base);
+#ifdef CONFIG_X86_32
+       paravirt_alloc_pt(&init_mm, page_to_pfn(base));
+#endif
+
        for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE)
-               pbase[i] = pfn_pte(addr >> PAGE_SHIFT, ref_prot);
+               set_pte(&pbase[i], pfn_pte(addr >> PAGE_SHIFT, ref_prot));
+
+       /*
+        * Install the new, split up pagetable:
+        */
+       __set_pmd_pte(kpte, address, mk_pte(base, ref_prot));
+       base = NULL;
+
+out_unlock:
+       spin_unlock_irqrestore(&pgd_lock, flags);
+
+       if (base)
+               __free_pages(base, 0);
 
-       return base;
+       return 0;
 }
 
 static int
 __change_page_attr(unsigned long address, struct page *page, pgprot_t prot)
 {
+       pgprot_t ref_prot2, oldprot;
        struct page *kpte_page;
+       int level, err = 0;
        pte_t *kpte;
-       pgprot_t ref_prot2, oldprot;
-       int level;
 
 repeat:
        kpte = lookup_address(address, &level);
@@ -88,22 +145,12 @@ repeat:
        if (level == 4) {
                set_pte_atomic(kpte, mk_pte(page, prot));
        } else {
-               /*
-                * split_large_page will take the reference for this
-                * change_page_attr on the split page.
-                */
-               struct page *split;
-
-               ref_prot2 = pte_pgprot(pte_clrhuge(*kpte));
-               split = split_large_page(address, ref_prot2);
-               if (!split)
-                       return -ENOMEM;
-               pgprot_val(ref_prot2) &= ~_PAGE_NX;
-               set_pte_atomic(kpte, mk_pte(split, ref_prot2));
-               goto repeat;
+               err = split_large_page(kpte, address);
+               if (!err)
+                       goto repeat;
        }
 
-       return 0;
+       return err;
 }
 
 /**