1 files changed, 249 insertions, 0 deletions
diff --git a/arch/x86_64/mm/pageattr_64.c b/arch/x86_64/mm/pageattr_64.c
new file mode 100644
index 00000000000..10b9809ce82
--- /dev/null
+++ b/arch/x86_64/mm/pageattr_64.c
@@ -0,0 +1,249 @@
+/* 
+ * Copyright 2002 Andi Kleen, SuSE Labs. 
+ * Thanks to Ben LaHaise for precious feedback.
+ */ 
+
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/highmem.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <asm/uaccess.h>
+#include <asm/processor.h>
+#include <asm/tlbflush.h>
+#include <asm/io.h>
+
+pte_t *lookup_address(unsigned long address)
+{ 
+	pgd_t *pgd = pgd_offset_k(address);
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *pte;
+	if (pgd_none(*pgd))
+		return NULL;
+	pud = pud_offset(pgd, address);
+	if (!pud_present(*pud))
+		return NULL; 
+	pmd = pmd_offset(pud, address);
+	if (!pmd_present(*pmd))
+		return NULL; 
+	if (pmd_large(*pmd))
+		return (pte_t *)pmd;
+	pte = pte_offset_kernel(pmd, address);
+	if (pte && !pte_present(*pte))
+		pte = NULL; 
+	return pte;
+} 
+
+static struct page *split_large_page(unsigned long address, pgprot_t prot,
+				     pgprot_t ref_prot)
+{ 
+	int i; 
+	unsigned long addr;
+	struct page *base = alloc_pages(GFP_KERNEL, 0);
+	pte_t *pbase;
+	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; 
+	pbase = (pte_t *)page_address(base);
+	for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE) {
+		pbase[i] = pfn_pte(addr >> PAGE_SHIFT, 
+				   addr == address ? prot : ref_prot);
+	}
+	return base;
+} 
+
+static void cache_flush_page(void *adr)
+{
+	int i;
+	for (i = 0; i < PAGE_SIZE; i += boot_cpu_data.x86_clflush_size)
+		asm volatile("clflush (%0)" :: "r" (adr + i));
+}
+
+static void flush_kernel_map(void *arg)
+{
+	struct list_head *l = (struct list_head *)arg;
+	struct page *pg;
+
+	/* 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)
+		asm volatile("wbinvd" ::: "memory");
+	else list_for_each_entry(pg, l, lru) {
+		void *adr = page_address(pg);
+		cache_flush_page(adr);
+	}
+	__flush_tlb_all();
+}
+
+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)
+{
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t large_pte;
+	unsigned long pfn;
+
+	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)
+{ 
+	pte_t *kpte; 
+	struct page *kpte_page;
+	pgprot_t ref_prot2;
+
+	kpte = lookup_address(address);
+	if (!kpte) return 0;
+	kpte_page = virt_to_page(((unsigned long)kpte) & PAGE_MASK);
+	BUG_ON(PageLRU(kpte_page));
+	BUG_ON(PageCompound(kpte_page));
+	if (pgprot_val(prot) != pgprot_val(ref_prot)) { 
+		if (!pte_huge(*kpte)) {
+			set_pte(kpte, pfn_pte(pfn, 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, prot, ref_prot2);
+			if (!split)
+				return -ENOMEM;
+			set_pte(kpte, mk_pte(split, ref_prot2));
+			kpte_page = split;
+		}
+		page_private(kpte_page)++;
+	} else if (!pte_huge(*kpte)) {
+		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.
+ * 
+ * The caller needs to ensure that there are no conflicting mappings elsewhere.
+ * This function only deals with the kernel linear map.
+ * 
+ * Caller must call global_flush_tlb() after this.
+ */
+int change_page_attr_addr(unsigned long address, int numpages, pgprot_t prot)
+{
+	int err = 0, kernel_map = 0;
+	int i; 
+
+	if (address >= __START_KERNEL_map
+	    && address < __START_KERNEL_map + KERNEL_TEXT_SIZE) {
+		address = (unsigned long)__va(__pa(address));
+		kernel_map = 1;
+	}
+
+	down_write(&init_mm.mmap_sem);
+	for (i = 0; i < numpages; i++, address += PAGE_SIZE) {
+		unsigned long pfn = __pa(address) >> PAGE_SHIFT;
+
+		if (!kernel_map || pte_present(pfn_pte(0, prot))) {
+			err = __change_page_attr(address, pfn, prot, PAGE_KERNEL);
+			if (err)
+				break;
+		}
+		/* Handle kernel mapping too which aliases part of the
+		 * lowmem */
+		if (__pa(address) < KERNEL_TEXT_SIZE) {
+			unsigned long addr2;
+			pgprot_t prot2;
+			addr2 = __START_KERNEL_map + __pa(address);
+			/* Make sure the kernel mappings stay executable */
+			prot2 = pte_pgprot(pte_mkexec(pfn_pte(0, prot)));
+			err = __change_page_attr(addr2, pfn, prot2,
+						 PAGE_KERNEL_EXEC);
+		} 
+	} 	
+	up_write(&init_mm.mmap_sem); 
+	return err;
+}
+
+/* Don't call this for MMIO areas that may not have a mem_map entry */
+int change_page_attr(struct page *page, int numpages, pgprot_t prot)
+{
+	unsigned long addr = (unsigned long)page_address(page);
+	return change_page_attr_addr(addr, numpages, prot);
+}
+
+void global_flush_tlb(void)
+{ 
+	struct page *pg, *next;
+	struct list_head l;
+
+	down_read(&init_mm.mmap_sem);
+	list_replace_init(&deferred_pages, &l);
+	up_read(&init_mm.mmap_sem);
+
+	flush_map(&l);
+
+	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);
+	} 
+} 
+
+EXPORT_SYMBOL(change_page_attr);
+EXPORT_SYMBOL(global_flush_tlb);