[PATCH] change_page_attr and AGP update

Add change_page_attr to change page attributes for the kernel linear map.

Fix AGP driver to use change_page_attr for the AGP buffer.

Clean up AGP driver a bit (only tested on i386/VIA+AMD)

Change ioremap_nocache to use change_page_attr to avoid mappings with
conflicting caching attributes.

3 files changed, 265 insertions, 4 deletions

diff --git a/arch/i386/mm/Makefile b/arch/i386/mm/Makefile
index 73e25bd3022a..67df8b6f6594 100644
--- a/arch/i386/mm/Makefile
+++ b/arch/i386/mm/Makefile
@@ -9,6 +9,7 @@
 
 O_TARGET := mm.o
 
-obj-y	 := init.o fault.o ioremap.o extable.o
+obj-y	 := init.o fault.o ioremap.o extable.o pageattr.o
+export-objs := pageattr.o
 
 include $(TOPDIR)/Rules.make
diff --git a/arch/i386/mm/ioremap.c b/arch/i386/mm/ioremap.c
index f81fae4ff7a9..4ba5641b271f 100644
--- a/arch/i386/mm/ioremap.c
+++ b/arch/i386/mm/ioremap.c
@@ -10,12 +10,13 @@
 
 #include <linux/vmalloc.h>
 #include <linux/init.h>
+#include <linux/slab.h>
 #include <asm/io.h>
 #include <asm/pgalloc.h>
 #include <asm/fixmap.h>
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
-
+#include <asm/pgtable.h>
 
 static inline void remap_area_pte(pte_t * pte, unsigned long address, unsigned long size,
 	unsigned long phys_addr, unsigned long flags)
@@ -155,6 +156,7 @@ void * __ioremap(unsigned long phys_addr, unsigned long size, unsigned long flag
 	area = get_vm_area(size, VM_IOREMAP);
 	if (!area)
 		return NULL;
+	area->phys_addr = phys_addr;
 	addr = area->addr;
 	if (remap_area_pages(VMALLOC_VMADDR(addr), phys_addr, size, flags)) {
 		vfree(addr);
@@ -163,10 +165,71 @@ void * __ioremap(unsigned long phys_addr, unsigned long size, unsigned long flag
 	return (void *) (offset + (char *)addr);
 }
 
+
+/**
+ * ioremap_nocache     -   map bus memory into CPU space
+ * @offset:    bus address of the memory
+ * @size:      size of the resource to map
+ *
+ * ioremap_nocache performs a platform specific sequence of operations to
+ * make bus memory CPU accessible via the readb/readw/readl/writeb/
+ * writew/writel functions and the other mmio helpers. The returned
+ * address is not guaranteed to be usable directly as a virtual
+ * address. 
+ *
+ * This version of ioremap ensures that the memory is marked uncachable
+ * on the CPU as well as honouring existing caching rules from things like
+ * the PCI bus. Note that there are other caches and buffers on many 
+ * busses. In particular driver authors should read up on PCI writes
+ *
+ * It's useful if some control registers are in such an area and
+ * write combining or read caching is not desirable:
+ * 
+ * Must be freed with iounmap.
+ */
+
+void *ioremap_nocache (unsigned long phys_addr, unsigned long size)
+{
+	void *p = __ioremap(phys_addr, size, _PAGE_PCD);
+	if (!p) 
+		return p; 
+
+	if (phys_addr + size < virt_to_phys(high_memory)) { 
+		struct page *ppage = virt_to_page(__va(phys_addr));		
+		unsigned long npages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
+
+		BUG_ON(phys_addr+size > (unsigned long)high_memory);
+		BUG_ON(phys_addr + size < phys_addr);
+
+		if (change_page_attr(ppage, npages, PAGE_KERNEL_NOCACHE) < 0) { 
+			iounmap(p); 
+			p = NULL;
+		}
+	} 
+
+	return p;					
+}
+
 void iounmap(void *addr)
 {
-	if (addr > high_memory)
-		return vfree((void *) (PAGE_MASK & (unsigned long) addr));
+	struct vm_struct *p;
+	if (addr < high_memory) 
+		return; 
+	p = remove_kernel_area(addr); 
+	if (!p) { 
+		printk("__iounmap: bad address %p\n", addr);
+		return;
+	} 
+
+	BUG_ON(p->phys_addr == 0);  /* not allocated with ioremap */	
+
+	vmfree_area_pages(VMALLOC_VMADDR(p->addr), p->size);	
+	if (p->flags && p->phys_addr < virt_to_phys(high_memory)) { 
+		change_page_attr(virt_to_page(__va(p->phys_addr)),
+				 p->size >> PAGE_SHIFT,
+				 PAGE_KERNEL); 				 
+	} 
+	kfree(p); 
 }
 
 void __init *bt_ioremap(unsigned long phys_addr, unsigned long size)
diff --git a/arch/i386/mm/pageattr.c b/arch/i386/mm/pageattr.c
new file mode 100644
index 000000000000..c5e2374b6bc7
--- /dev/null
+++ b/arch/i386/mm/pageattr.c
@@ -0,0 +1,197 @@
+/* 
+ * 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>
+
+static inline pte_t *lookup_address(unsigned long address) 
+{ 
+	pgd_t *pgd = pgd_offset_k(address); 
+	pmd_t *pmd = pmd_offset(pgd, address); 	       
+	if (pmd_large(*pmd))
+		return (pte_t *)pmd;
+        return pte_offset_kernel(pmd, address);
+} 
+
+static struct page *split_large_page(unsigned long address, pgprot_t 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 : PAGE_KERNEL);
+	}
+	return base;
+} 
+
+static void flush_kernel_map(void *dummy) 
+{ 
+	/* Could use CLFLUSH here if the CPU supports it (Hammer,P4) */
+	if (boot_cpu_data.x86_model >= 4) 
+		asm volatile("wbinvd":::"memory"); 
+	/* Flush all to work around Errata in early athlons regarding 
+	 * large page flushing. 
+	 */
+	__flush_tlb_all(); 	
+}
+
+static void set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte) 
+{ 
+	set_pte_atomic(kpte, pte); 	/* change init_mm */
+#ifndef CONFIG_X86_PAE
+	{
+		struct list_head *l;
+		spin_lock(&mmlist_lock);
+		list_for_each(l, &init_mm.mmlist) { 
+			struct mm_struct *mm = list_entry(l, struct mm_struct, mmlist);
+			pmd_t *pmd = pmd_offset(pgd_offset(mm, address), address);
+			set_pte_atomic((pte_t *)pmd, pte);
+		} 
+		spin_unlock(&mmlist_lock);
+	}
+#endif
+}
+
+/* 
+ * No more special protections in this 2/4MB area - revert to a
+ * large page again. 
+ */
+static inline void revert_page(struct page *kpte_page, unsigned long address)
+{
+	pte_t *linear = (pte_t *) 
+		pmd_offset(pgd_offset(&init_mm, address), address);
+	set_pmd_pte(linear,  address,
+		    pfn_pte((__pa(address) & LARGE_PAGE_MASK) >> PAGE_SHIFT,
+			    PAGE_KERNEL_LARGE));
+}
+
+static int
+__change_page_attr(struct page *page, pgprot_t prot, struct page **oldpage) 
+{ 
+	pte_t *kpte; 
+	unsigned long address;
+	struct page *kpte_page;
+
+#ifdef CONFIG_HIGHMEM
+	if (page >= highmem_start_page) 
+		BUG(); 
+#endif
+	address = (unsigned long)page_address(page);
+
+	kpte = lookup_address(address);
+	kpte_page = virt_to_page(((unsigned long)kpte) & PAGE_MASK);
+	if (pgprot_val(prot) != pgprot_val(PAGE_KERNEL)) { 
+		if ((pte_val(*kpte) & _PAGE_PSE) == 0) { 
+			pte_t old = *kpte;
+			pte_t standard = mk_pte(page, PAGE_KERNEL); 
+
+			set_pte_atomic(kpte, mk_pte(page, prot)); 
+			if (pte_same(old,standard))
+				atomic_inc(&kpte_page->count);
+		} else {
+			struct page *split = split_large_page(address, prot); 
+			if (!split)
+				return -ENOMEM;
+			set_pmd_pte(kpte,address,mk_pte(split, PAGE_KERNEL));
+		}	
+	} else if ((pte_val(*kpte) & _PAGE_PSE) == 0) { 
+		set_pte_atomic(kpte, mk_pte(page, PAGE_KERNEL));
+		atomic_dec(&kpte_page->count); 
+	}
+
+	if (cpu_has_pse && (atomic_read(&kpte_page->count) == 1)) { 
+		*oldpage = kpte_page;
+		revert_page(kpte_page, address);
+	} 
+	return 0;
+} 
+
+static inline void flush_map(void)
+{	
+#ifdef CONFIG_SMP 
+	smp_call_function(flush_kernel_map, NULL, 1, 1);
+#endif	
+	flush_kernel_map(NULL);
+}
+
+struct deferred_page { 
+	struct deferred_page *next; 
+	struct page *fpage;
+}; 
+static struct deferred_page *df_list; /* protected by init_mm.mmap_sem */
+
+/*
+ * 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(struct page *page, int numpages, pgprot_t prot)
+{
+	int err = 0; 
+	struct page *fpage; 
+	int i; 
+
+	down_write(&init_mm.mmap_sem);
+	for (i = 0; i < numpages; i++, page++) { 
+		fpage = NULL;
+		err = __change_page_attr(page, prot, &fpage); 
+		if (err) 
+			break; 
+		if (fpage) { 
+			struct deferred_page *df;
+			df = kmalloc(sizeof(struct deferred_page), GFP_KERNEL); 
+			if (!df) {
+				flush_map();
+				__free_page(fpage);
+			} else { 
+				df->next = df_list;
+				df->fpage = fpage;				
+				df_list = df;
+			} 			
+		} 
+	} 	
+	up_write(&init_mm.mmap_sem); 
+	return err;
+}
+
+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);
+	flush_map();
+	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);