x86: simplify pageattr_64.c

simplify pageattr_64.c.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/mm/pageattr_64.c

@@ -9,6 +9,14 @@
 #include <linux/slab.h>
 #include <linux/mm.h>
 
+void clflush_cache_range(void *addr, int size)
+{
+	int i;
+
+	for (i = 0; i < size; i += boot_cpu_data.x86_clflush_size)
+		clflush(addr+i);
+}
+
 #include <asm/processor.h>
 #include <asm/tlbflush.h>
 #include <asm/uaccess.h>
@@ -47,12 +55,6 @@ split_large_page(unsigned long address, pgprot_t prot, pgprot_t ref_prot)
 	base = alloc_pages(GFP_KERNEL, 0);
 	if (!base)
 		return NULL;
-	/*
-	 * page_private is used to track the number of entries in
-	 * the page table page have non standard attributes.
-	 */
-	SetPagePrivate(base);
-	page_private(base) = 0;
 
 	address = __pa(address);
 	addr = address & LARGE_PAGE_MASK;
@@ -64,80 +66,13 @@ split_large_page(unsigned long address, pgprot_t prot, pgprot_t ref_prot)
 	return base;
 }
 
-void clflush_cache_range(void *addr, int size)
-{
-	int i;
-
-	for (i = 0; i < size; i += boot_cpu_data.x86_clflush_size)
-		clflush(addr+i);
-}
-
-static void flush_kernel_map(void *arg)
-{
-	struct list_head *l = (struct list_head *)arg;
-	struct page *pg;
-
-	__flush_tlb_all();
-
-	/* When clflush is available always use it because it is
-	   much cheaper than WBINVD. */
-	/* clflush is still broken. Disable for now. */
-	if (1 || !cpu_has_clflush) {
-		wbinvd();
-	} else {
-		list_for_each_entry(pg, l, lru) {
-			void *addr = page_address(pg);
-
-			clflush_cache_range(addr, PAGE_SIZE);
-		}
-	}
-}
-
-static inline void flush_map(struct list_head *l)
-{
-	on_each_cpu(flush_kernel_map, l, 1, 1);
-}
-
-static LIST_HEAD(deferred_pages); /* protected by init_mm.mmap_sem */
-
-static inline void save_page(struct page *fpage)
-{
-	if (!test_and_set_bit(PG_arch_1, &fpage->flags))
-		list_add(&fpage->lru, &deferred_pages);
-}
-
-/*
- * No more special protections in this 2/4MB area - revert to a
- * large page again.
- */
-static void revert_page(unsigned long address, pgprot_t ref_prot)
-{
-	unsigned long pfn;
-	pgd_t *pgd;
-	pud_t *pud;
-	pmd_t *pmd;
-	pte_t large_pte;
-
-	pgd = pgd_offset_k(address);
-	BUG_ON(pgd_none(*pgd));
-	pud = pud_offset(pgd, address);
-	BUG_ON(pud_none(*pud));
-	pmd = pmd_offset(pud, address);
-	BUG_ON(pmd_val(*pmd) & _PAGE_PSE);
-	pfn = (__pa(address) & LARGE_PAGE_MASK) >> PAGE_SHIFT;
-	large_pte = pfn_pte(pfn, ref_prot);
-	large_pte = pte_mkhuge(large_pte);
-
-	set_pte((pte_t *)pmd, large_pte);
-}
-
 static int
 __change_page_attr(unsigned long address, unsigned long pfn, pgprot_t prot,
 		   pgprot_t ref_prot)
 {
 	struct page *kpte_page;
-	pgprot_t ref_prot2;
 	pte_t *kpte;
+	pgprot_t ref_prot2, oldprot;
 	int level;
 
 	kpte = lookup_address(address, &level);
@@ -145,8 +80,12 @@ __change_page_attr(unsigned long address, unsigned long pfn, pgprot_t prot,
 		return 0;
 
 	kpte_page = virt_to_page(kpte);
+	oldprot = pte_pgprot(*kpte);
 	BUG_ON(PageLRU(kpte_page));
 	BUG_ON(PageCompound(kpte_page));
+	ref_prot = canon_pgprot(ref_prot);
+	prot = canon_pgprot(prot);
+
 	if (pgprot_val(prot) != pgprot_val(ref_prot)) {
 		if (level == 4) {
 			set_pte(kpte, pfn_pte(pfn, prot));
@@ -165,38 +104,29 @@ __change_page_attr(unsigned long address, unsigned long pfn, pgprot_t prot,
 			set_pte(kpte, mk_pte(split, ref_prot2));
 			kpte_page = split;
 		}
-		page_private(kpte_page)++;
 	} else {
 		if (level == 4) {
 			set_pte(kpte, pfn_pte(pfn, ref_prot));
-			BUG_ON(page_private(kpte_page) == 0);
-			page_private(kpte_page)--;
 		} else
 			BUG();
 	}
 
-	/* on x86-64 the direct mapping set at boot is not using 4k pages */
-	BUG_ON(PageReserved(kpte_page));
-
-	save_page(kpte_page);
-	if (page_private(kpte_page) == 0)
-		revert_page(address, ref_prot);
 	return 0;
 }
 
-/*
- * Change the page attributes of an page in the linear mapping.
- *
- * This should be used when a page is mapped with a different caching policy
- * than write-back somewhere - some CPUs do not like it when mappings with
- * different caching policies exist. This changes the page attributes of the
- * in kernel linear mapping too.
+/**
+ * change_page_attr_addr - Change page table attributes in linear mapping
+ * @address: Virtual address in linear mapping.
+ * @numpages: Number of pages to change
+ * @prot:    New page table attribute (PAGE_*)
  *
- * The caller needs to ensure that there are no conflicting mappings elsewhere.
- * This function only deals with the kernel linear map.
+ * Change page attributes of a page in the direct mapping. This is a variant
+ * of change_page_attr() that also works on memory holes that do not have
+ * mem_map entry (pfn_valid() is false).
  *
- * Caller must call global_flush_tlb() after this.
+ * See change_page_attr() documentation for more details.
  */
+
 int change_page_attr_addr(unsigned long address, int numpages, pgprot_t prot)
 {
 	int err = 0, kernel_map = 0, i;
@@ -236,7 +166,26 @@ int change_page_attr_addr(unsigned long address, int numpages, pgprot_t prot)
 	return err;
 }
 
-/* Don't call this for MMIO areas that may not have a mem_map entry */
+/**
+ * change_page_attr - Change page table attributes in the linear mapping.
+ * @page: First page to change
+ * @numpages: Number of pages to change
+ * @prot: New protection/caching type (PAGE_*)
+ *
+ * Returns 0 on success, otherwise a negated errno.
+ *
+ * This should be used when a page is mapped with a different caching policy
+ * than write-back somewhere - some CPUs do not like it when mappings with
+ * different caching policies exist. This changes the page attributes of the
+ * in kernel linear mapping too.
+ *
+ * Caller must call global_flush_tlb() later to make the changes active.
+ *
+ * The caller needs to ensure that there are no conflicting mappings elsewhere
+ * (e.g. in user space) * This function only deals with the kernel linear map.
+ *
+ * For MMIO areas without mem_map use change_page_attr_addr() instead.
+ */
 int change_page_attr(struct page *page, int numpages, pgprot_t prot)
 {
 	unsigned long addr = (unsigned long)page_address(page);
@@ -245,29 +194,22 @@ int change_page_attr(struct page *page, int numpages, pgprot_t prot)
 }
 EXPORT_SYMBOL(change_page_attr);
 
-void global_flush_tlb(void)
+static void flush_kernel_map(void *arg)
 {
-	struct page *pg, *next;
-	struct list_head l;
-
 	/*
-	 * Write-protect the semaphore, to exclude two contexts
-	 * doing a list_replace_init() call in parallel and to
-	 * exclude new additions to the deferred_pages list:
+	 * Flush all to work around Errata in early athlons regarding
+	 * large page flushing.
 	 */
-	down_write(&init_mm.mmap_sem);
-	list_replace_init(&deferred_pages, &l);
-	up_write(&init_mm.mmap_sem);
+	__flush_tlb_all();
 
-	flush_map(&l);
+	if (boot_cpu_data.x86_model >= 4)
+		wbinvd();
+}
 
-	list_for_each_entry_safe(pg, next, &l, lru) {
-		list_del(&pg->lru);
-		clear_bit(PG_arch_1, &pg->flags);
-		if (page_private(pg) != 0)
-			continue;
-		ClearPagePrivate(pg);
-		__free_page(pg);
-	}
+void global_flush_tlb(void)
+{
+	BUG_ON(irqs_disabled());
+
+	on_each_cpu(flush_kernel_map, NULL, 1, 1);
 }
 EXPORT_SYMBOL(global_flush_tlb);