1 files changed, 235 insertions, 0 deletions
diff --git a/arch/x86_64/mm/pageattr.c b/arch/x86_64/mm/pageattr.c
new file mode 100644
index 000000000000..94862e1ec032
--- /dev/null
+++ b/arch/x86_64/mm/pageattr.c
@@ -0,0 +1,235 @@
+/* 
+ * Copyright 2002 Andi Kleen, SuSE Labs. 
+ * Thanks to Ben LaHaise for precious feedback.
+ */ 
+
+#include <linux/config.h>
+#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>
+
+static inline 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;
+	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 flush_kernel_map(void *address) 
+{
+	if (0 && address && cpu_has_clflush) {
+		/* is this worth it? */ 
+		int i;
+		for (i = 0; i < PAGE_SIZE; i += boot_cpu_data.x86_clflush_size) 
+			asm volatile("clflush (%0)" :: "r" (address + i)); 
+	} else
+		asm volatile("wbinvd":::"memory"); 
+	if (address)
+		__flush_tlb_one(address);
+	else
+		__flush_tlb_all();
+}
+
+
+static inline void flush_map(unsigned long address)
+{	
+	on_each_cpu(flush_kernel_map, (void *)address, 1, 1);
+}
+
+struct deferred_page { 
+	struct deferred_page *next; 
+	struct page *fpage;
+	unsigned long address;
+}; 
+static struct deferred_page *df_list; /* protected by init_mm.mmap_sem */
+
+static inline void save_page(unsigned long address, struct page *fpage)
+{
+	struct deferred_page *df;
+	df = kmalloc(sizeof(struct deferred_page), GFP_KERNEL); 
+	if (!df) {
+		flush_map(address);
+		__free_page(fpage);
+	} else { 
+		df->next = df_list;
+		df->fpage = fpage;
+		df->address = address;
+		df_list = df;
+	} 			
+}
+
+/* 
+ * 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;
+
+	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);
+	pgprot_val(ref_prot) |= _PAGE_PSE;
+	large_pte = mk_pte_phys(__pa(address) & LARGE_PAGE_MASK, ref_prot);
+	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;
+	unsigned kpte_flags;
+	kpte = lookup_address(address);
+	if (!kpte) return 0;
+	kpte_page = virt_to_page(((unsigned long)kpte) & PAGE_MASK);
+	kpte_flags = pte_val(*kpte); 
+	if (pgprot_val(prot) != pgprot_val(ref_prot)) { 
+		if ((kpte_flags & _PAGE_PSE) == 0) { 
+			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 = split_large_page(address, prot, ref_prot); 
+			if (!split)
+				return -ENOMEM;
+			set_pte(kpte,mk_pte(split, ref_prot));
+			kpte_page = split;
+		}	
+		get_page(kpte_page);
+	} else if ((kpte_flags & _PAGE_PSE) == 0) { 
+		set_pte(kpte, pfn_pte(pfn, ref_prot));
+		__put_page(kpte_page);
+	} else
+		BUG();
+
+	/* on x86-64 the direct mapping set at boot is not using 4k pages */
+ 	BUG_ON(PageReserved(kpte_page));
+
+	switch (page_count(kpte_page)) {
+ 	case 1:
+		save_page(address, kpte_page); 		     
+		revert_page(address, ref_prot);
+		break;
+ 	case 0:
+ 		BUG(); /* memleak and failed 2M page regeneration */
+ 	}
+	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; 
+	int i; 
+
+	down_write(&init_mm.mmap_sem);
+	for (i = 0; i < numpages; i++, address += PAGE_SIZE) {
+		unsigned long pfn = __pa(address) >> PAGE_SHIFT;
+
+		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 = prot;
+			addr2 = __START_KERNEL_map + __pa(address);
+ 			pgprot_val(prot2) &= ~_PAGE_NX;
+			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 deferred_page *df, *next_df;
+
+	down_read(&init_mm.mmap_sem);
+	df = xchg(&df_list, NULL);
+	up_read(&init_mm.mmap_sem);
+	if (!df)
+		return;
+	flush_map((df && !df->next) ? df->address : 0);
+	for (; df; df = next_df) { 
+		next_df = df->next;
+		if (df->fpage) 
+			__free_page(df->fpage);
+		kfree(df);
+	} 
+} 
+
+EXPORT_SYMBOL(change_page_attr);
+EXPORT_SYMBOL(global_flush_tlb);