[patch] pageattr update

[patch] pageattr update

[Benjamin LaHaise]

Hey Andi, everyone,

Below are some updates to the pageattr patch you posted earlier.  The 
first set of changes were to add change_page_attrs in several paths 
where the AGP and DRM code would allocate a page and then call 
ioremap_nocache on it to create an uncachable mapping.  Secondly, I 
removed the #ifdef __i386__ around the change_page_attr hook, and 
instead put dummy macros in the headers for the various other archs.  
There was a race in pageattr.c that would make the P4 unhappy, so I 
moved the pte page free to after the tlb flush.  The tlb flush was 
not flushing global pages, so I replaced the code with a call to 
flush_tlb_all() to do the job.  Lastly, since the top page of the 
page tables on x86 is unique to each mm and contains copies of the 
pmd entries in non-PAE mode, I added a function to walk all mms via 
the mmlist to update the pmds before the tlb flush.

With these changes in place, my X server is starting up and using 
DRM happily.  Without the global TLB flush, X would hang on startup.  
Could people please review and test this version?  Thanks,

		-ben
-- 
"You will be reincarnated as a toad; and you will be much happier."

:r ~/patches/v2.4/v2.4.19-pre10-pageattr-B1.diff
diff -urN v2.4.19-pre10/arch/i386/mm/Makefile pageattr-v2.4.19-pre10.diff/arch/i386/mm/Makefile
--- v2.4.19-pre10/arch/i386/mm/Makefile	Fri Dec 29 17:07:20 2000
+++ pageattr-v2.4.19-pre10.diff/arch/i386/mm/Makefile	Tue Jun 11 21:41:54 2002
@@ -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 -urN v2.4.19-pre10/arch/i386/mm/pageattr.c pageattr-v2.4.19-pre10.diff/arch/i386/mm/pageattr.c
--- v2.4.19-pre10/arch/i386/mm/pageattr.c	Wed Dec 31 19:00:00 1969
+++ pageattr-v2.4.19-pre10.diff/arch/i386/mm/pageattr.c	Wed Jun 12 00:37:37 2002
@@ -0,0 +1,173 @@
+/* 
+ * Copyright 2002 Andi Kleen, SuSE Labs. 
+ * Copyright 2002 Red Hat, Inc.
+ * Additional fixes by Benjamin LaHaise, Red Hat.
+ */ 
+
+#include <linux/config.h>
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/highmem.h>
+#include <linux/module.h>
+#include <asm/uaccess.h>
+#include <asm/processor.h>
+
+/* Should move most of this stuff into the appropiate includes */
+#define PAGE_LARGE (_PAGE_PSE|_PAGE_PRESENT) 
+#define LARGE_PAGE_MASK (~(LARGE_PAGE_SIZE-1))
+#define LARGE_PAGE_SIZE ((1UL << PMD_SHIFT)) 
+
+#ifdef CONFIG_DISCONTIGMEM
+#error you lose. sorry.
+#endif
+
+#ifdef CONFIG_X86_PAE
+/* note: PAT must be cleared also. assumes a PAE CPU also has PGE. */
+#define PAGE_KERNEL_4K \
+	__pgprot(_KERNPG_TABLE & ~(_PAGE_GLOBAL|_PAGE_DIRTY))
+#else
+#define PAGE_KERNEL_4K \
+	MAKE_GLOBAL(_KERNPG_TABLE & ~(_PAGE_DIRTY))
+#endif
+
+static inline pte_t *lookup_address(unsigned long address) 
+{ 
+	pte_t *pte;
+	pmd_t *pmd;	
+	pgd_t *pgd = pgd_offset(&init_mm, address); 
+
+	if ((pgd_val(*pgd) & PAGE_LARGE) == PAGE_LARGE)
+		return (pte_t *)pgd; 
+	pmd = pmd_offset(pgd, address); 	       
+	if ((pmd_val(*pmd) & PAGE_LARGE) == PAGE_LARGE)
+		return (pte_t *)pmd; 
+
+        return pte_offset(pmd, address);
+} 
+
+static pte_t *split_large_page(unsigned long address, pgprot_t prot)
+{ 
+	unsigned long addr;
+	int i; 
+	pte_t *base = (pte_t *) __get_free_page(GFP_KERNEL); 
+	if (!base) 
+		return NULL;
+	BUG_ON(atomic_read(&virt_to_page(base)->count) != 1); 	
+	address = __pa(address);
+	addr = address & LARGE_PAGE_MASK; 
+	for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE) {
+		base[i] = mk_pte_phys(addr, addr == address ? prot : PAGE_KERNEL);
+	}
+	return base;
+} 
+
+/*
+ * Update all kernel pmd entries in the system for the given address.
+ */
+static void update_all_kernel_pmds(unsigned long address, pte_t new_pmd)
+{
+	/* PAE can avoid this operation as all mms share the same
+	 * kernel pmds, so the update will propagate when the TLBs 
+	 * are flushed.
+	 */
+#if !defined(CONFIG_HIGHMEM64G)
+	struct mm_struct *mm = &init_mm;
+
+	spin_lock(&mmlist_lock);
+	for (;;) {
+		pmd_t *pmdp;
+		mm = list_entry(mm->mmlist.next, struct mm_struct, mmlist);
+		if (mm == &init_mm)
+			break;
+
+		pmdp = pmd_offset(pgd_offset(mm, address), address);
+		set_pte((pte_t *)pmdp, new_pmd);
+	}
+	spin_unlock(&mmlist_lock);
+#endif
+	return;
+}
+
+/*
+ * 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.
+ * When page is in highmem it must never be kmap'ed.
+ */
+int change_page_attr(struct page *page, pgprot_t prot) 
+{ 
+	int err; 
+	pte_t *kpte, *split; 
+	unsigned long address;
+	struct page *kpte_page;
+	struct page *page_to_free = NULL;
+
+#ifdef CONFIG_HIGHMEM
+	if (page >= highmem_start_page) { 
+		/* Hopefully not be mapped anywhere else. */
+		return 0; 
+	} 
+#endif
+
+	address = ((unsigned long)(page - mem_map) << PAGE_SHIFT) + __PAGE_OFFSET;
+
+	down_write(&init_mm.mmap_sem); 
+	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, standard = mk_pte(page, PAGE_KERNEL); 
+			/* Already a 4KB page. Just update it to the new protection.
+			 * Doesn't need to be atomic. It doesn't matter if dirty bits 
+			 * get lost.
+			 */
+			set_pte(kpte, mk_pte(page, prot)); 
+			if (!memcmp(&old,&standard,sizeof(pte_t))) 
+				atomic_inc(&kpte_page->count);
+		} else {
+			err = -ENOMEM; 
+			split = split_large_page(address, prot); 
+			if (!split)
+				goto out;
+
+			set_pte(kpte,mk_pte(virt_to_page(split), PAGE_KERNEL_4K));
+			update_all_kernel_pmds(address, *kpte);
+		}	
+	} else if ((pte_val(*kpte) & _PAGE_PSE) == 0) { 
+		/* just an ordinary page again - revert to standard mapping */	
+		set_pte(kpte, mk_pte(page, PAGE_KERNEL));
+		atomic_dec(&kpte_page->count); 
+		if (atomic_read(&kpte_page->count) == 1) {
+			/* no more special protections in this 4MB area - revert to
+			   large page again. */
+			pte_t *linear = (pte_t *) 
+				pmd_offset(pgd_offset(&init_mm, address), address);
+
+			set_pte(linear, 
+				mk_pte_phys(__pa(address & LARGE_PAGE_MASK),
+					    __pgprot(_KERNPG_TABLE|_PAGE_PSE)));
+			update_all_kernel_pmds(address, *linear);
+			page_to_free = kpte_page;
+		}
+	}
+
+	/* Kernel pages typically have the global bit set, so we must 
+	 * flush everything...
+	 */
+	flush_tlb_all();
+
+	if (NULL != page_to_free)
+		__free_page(page_to_free);
+	err = 0;
+ out:
+	up_write(&init_mm.mmap_sem); 
+	return err;
+} 
+
+EXPORT_SYMBOL(change_page_attr);
diff -urN v2.4.19-pre10/drivers/char/agp/agpgart_be.c pageattr-v2.4.19-pre10.diff/drivers/char/agp/agpgart_be.c
--- v2.4.19-pre10/drivers/char/agp/agpgart_be.c	Thu Jun  6 20:09:59 2002
+++ pageattr-v2.4.19-pre10.diff/drivers/char/agp/agpgart_be.c	Tue Jun 11 22:08:48 2002
@@ -397,7 +397,7 @@
 static void agp_generic_agp_enable(u32 mode)
 {
 	struct pci_dev *device = NULL;
-	u32 command, scratch, cap_id;
+	u32 command, scratch;
 	u8 cap_ptr;
 
 	pci_read_config_dword(agp_bridge.dev,
@@ -561,6 +561,7 @@
 					    agp_bridge.current_size;
 					break;
 				}
+				temp = agp_bridge.current_size;
 			} else {
 				agp_bridge.aperture_size_idx = i;
 			}
@@ -578,8 +579,10 @@
 	}
 	table_end = table + ((PAGE_SIZE * (1 << page_order)) - 1);
 
-	for (page = virt_to_page(table); page <= virt_to_page(table_end); page++)
+	for (page = virt_to_page(table); page <= virt_to_page(table_end); page++) {
 		SetPageReserved(page);
+		change_page_attr(page, __pgprot(__PAGE_KERNEL | _PAGE_PCD));
+	}
 
 	agp_bridge.gatt_table_real = (unsigned long *) table;
 	CACHE_FLUSH();
@@ -588,8 +591,10 @@
 	CACHE_FLUSH();
 
 	if (agp_bridge.gatt_table == NULL) {
-		for (page = virt_to_page(table); page <= virt_to_page(table_end); page++)
+		for (page = virt_to_page(table); page <= virt_to_page(table_end); page++) {
+			change_page_attr(page, PAGE_KERNEL);
 			ClearPageReserved(page);
+		}
 
 		free_pages((unsigned long) table, page_order);
 
@@ -655,8 +660,10 @@
 	table = (char *) agp_bridge.gatt_table_real;
 	table_end = table + ((PAGE_SIZE * (1 << page_order)) - 1);
 
-	for (page = virt_to_page(table); page <= virt_to_page(table_end); page++)
+	for (page = virt_to_page(table); page <= virt_to_page(table_end); page++) {
+		change_page_attr(page, PAGE_KERNEL);
 		ClearPageReserved(page);
+	}
 
 	free_pages((unsigned long) agp_bridge.gatt_table_real, page_order);
 	return 0;
@@ -769,6 +776,8 @@
 	if (page == NULL) {
 		return 0;
 	}
+	change_page_attr(page, __pgprot(__PAGE_KERNEL | _PAGE_PCD));
+
 	get_page(page);
 	LockPage(page);
 	atomic_inc(&agp_bridge.current_memory_agp);
@@ -785,6 +794,9 @@
 	}
 	
 	page = virt_to_page(pt);
+	change_page_attr(page, PAGE_KERNEL);
+	
+
 	put_page(page);
 	UnlockPage(page);
 	free_page((unsigned long) pt);
@@ -2243,9 +2255,11 @@
 	}
 	SetPageReserved(virt_to_page(page_map->real));
 	CACHE_FLUSH();
+	change_page_attr(virt_to_page(page_map->real), __pgprot(__PAGE_KERNEL | _PAGE_PCD));
 	page_map->remapped = ioremap_nocache(virt_to_phys(page_map->real), 
 					    PAGE_SIZE);
 	if (page_map->remapped == NULL) {
+		change_page_attr(virt_to_page(page_map->real), PAGE_KERNEL);
 		ClearPageReserved(virt_to_page(page_map->real));
 		free_page((unsigned long) page_map->real);
 		page_map->real = NULL;
@@ -2263,6 +2277,7 @@
 static void amd_free_page_map(amd_page_map *page_map)
 {
 	iounmap(page_map->remapped);
+	change_page_attr(virt_to_page(page_map->real), PAGE_KERNEL);
 	ClearPageReserved(virt_to_page(page_map->real));
 	free_page((unsigned long) page_map->real);
 }
@@ -2744,27 +2759,22 @@
 
 static unsigned long ali_alloc_page(void)
 {
-	struct page *page;
-	u32 temp;
-
-	page = alloc_page(GFP_KERNEL);
-	if (page == NULL)
+	unsigned long p = agp_generic_alloc_page(); 
+	if (!p) 
 		return 0;
 
-	get_page(page);
-	LockPage(page);
-	atomic_inc(&agp_bridge.current_memory_agp);
-
+	/* probably not needed anymore */
 	global_cache_flush();
 
 	if (agp_bridge.type == ALI_M1541) {
+		u32 temp;
 		pci_read_config_dword(agp_bridge.dev, ALI_CACHE_FLUSH_CTRL, &temp);
 		pci_write_config_dword(agp_bridge.dev, ALI_CACHE_FLUSH_CTRL,
 				(((temp & ALI_CACHE_FLUSH_ADDR_MASK) |
-				  virt_to_phys(page_address(page))) |
+				  virt_to_phys(p)) |
 				    ALI_CACHE_FLUSH_EN ));
 	}
-	return (unsigned long)page_address(page);
+	return p;
 }
 
 static void ali_destroy_page(unsigned long addr)
@@ -2786,11 +2796,7 @@
 				    ALI_CACHE_FLUSH_EN));
 	}
 
-	page = virt_to_page(pt);
-	put_page(page);
-	UnlockPage(page);
-	free_page((unsigned long) pt);
-	atomic_dec(&agp_bridge.current_memory_agp);
+	agp_generic_destroy_page(pt);
 }
 
 /* Setup function */
@@ -2872,9 +2878,11 @@
 	}
 	SetPageReserved(virt_to_page(page_map->real));
 	CACHE_FLUSH();
+	change_page_attr(virt_to_page(page_map->real), __pgprot(__PAGE_KERNEL | _PAGE_PCD));
 	page_map->remapped = ioremap_nocache(virt_to_phys(page_map->real), 
 					    PAGE_SIZE);
 	if (page_map->remapped == NULL) {
+		change_page_attr(virt_to_page(page_map->real), PAGE_KERNEL);
 		ClearPageReserved(virt_to_page(page_map->real));
 		free_page((unsigned long) page_map->real);
 		page_map->real = NULL;
@@ -2892,6 +2900,7 @@
 static void serverworks_free_page_map(serverworks_page_map *page_map)
 {
 	iounmap(page_map->remapped);
+	change_page_attr(virt_to_page(page_map->real), PAGE_KERNEL);
 	ClearPageReserved(virt_to_page(page_map->real));
 	free_page((unsigned long) page_map->real);
 }
diff -urN v2.4.19-pre10/drivers/char/drm-4.0/mga_dma.c pageattr-v2.4.19-pre10.diff/drivers/char/drm-4.0/mga_dma.c
--- v2.4.19-pre10/drivers/char/drm-4.0/mga_dma.c	Thu Mar  7 16:39:58 2002
+++ pageattr-v2.4.19-pre10.diff/drivers/char/drm-4.0/mga_dma.c	Tue Jun 11 22:01:01 2002
@@ -641,6 +641,7 @@
 		   	iounmap(dev_priv->status_page);
 		}
 	   	if(dev_priv->real_status_page != 0UL) {
+			change_page_attr(virt_to_page(dev_priv->real_status_page), PAGE_KERNEL);
 		   	mga_free_page(dev, dev_priv->real_status_page);
 		}
 	   	if(dev_priv->prim_bufs != NULL) {
@@ -731,6 +732,7 @@
 		return -ENOMEM;
 	}
 
+	change_page_attr(virt_to_page(dev_priv->real_status_page), __pgprot(__PAGE_KERNEL | _PAGE_PCD));
    	dev_priv->status_page =
 		ioremap_nocache(virt_to_bus((void *)dev_priv->real_status_page),
 				PAGE_SIZE);
diff -urN v2.4.19-pre10/include/asm-alpha/pgtable.h pageattr-v2.4.19-pre10.diff/include/asm-alpha/pgtable.h
--- v2.4.19-pre10/include/asm-alpha/pgtable.h	Thu Jun  6 20:10:08 2002
+++ pageattr-v2.4.19-pre10.diff/include/asm-alpha/pgtable.h	Tue Jun 11 22:17:39 2002
@@ -364,4 +364,6 @@
 /* We have our own get_unmapped_area to cope with ADDR_LIMIT_32BIT.  */
 #define HAVE_ARCH_UNMAPPED_AREA
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* _ALPHA_PGTABLE_H */
diff -urN v2.4.19-pre10/include/asm-arm/pgtable.h pageattr-v2.4.19-pre10.diff/include/asm-arm/pgtable.h
--- v2.4.19-pre10/include/asm-arm/pgtable.h	Thu Jun  6 20:10:08 2002
+++ pageattr-v2.4.19-pre10.diff/include/asm-arm/pgtable.h	Tue Jun 11 22:17:48 2002
@@ -175,6 +175,7 @@
 #include <asm-generic/pgtable.h>
 
 extern void pgtable_cache_init(void);
+#define change_page_attr(page, prot)	do { } while (0)
 
 #endif /* !__ASSEMBLY__ */
 
diff -urN v2.4.19-pre10/include/asm-cris/pgtable.h pageattr-v2.4.19-pre10.diff/include/asm-cris/pgtable.h
--- v2.4.19-pre10/include/asm-cris/pgtable.h	Thu Jun  6 20:10:08 2002
+++ pageattr-v2.4.19-pre10.diff/include/asm-cris/pgtable.h	Tue Jun 11 22:17:59 2002
@@ -520,4 +520,6 @@
  */
 #define pgtable_cache_init()   do { } while (0)
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* _CRIS_PGTABLE_H */
diff -urN v2.4.19-pre10/include/asm-i386/pgtable.h pageattr-v2.4.19-pre10.diff/include/asm-i386/pgtable.h
--- v2.4.19-pre10/include/asm-i386/pgtable.h	Thu Jun  6 20:10:08 2002
+++ pageattr-v2.4.19-pre10.diff/include/asm-i386/pgtable.h	Tue Jun 11 23:59:22 2002
@@ -347,6 +347,9 @@
 #define pte_to_swp_entry(pte)		((swp_entry_t) { (pte).pte_low })
 #define swp_entry_to_pte(x)		((pte_t) { (x).val })
 
+struct page;
+int change_page_attr(struct page *, pgprot_t prot);
+
 #endif /* !__ASSEMBLY__ */
 
 /* Needs to be defined here and not in linux/mm.h, as it is arch dependent */
diff -urN v2.4.19-pre10/include/asm-ia64/pgtable.h pageattr-v2.4.19-pre10.diff/include/asm-ia64/pgtable.h
--- v2.4.19-pre10/include/asm-ia64/pgtable.h	Thu Jun  6 20:10:08 2002
+++ pageattr-v2.4.19-pre10.diff/include/asm-ia64/pgtable.h	Tue Jun 11 22:18:10 2002
@@ -473,4 +473,6 @@
  */
 #define pgtable_cache_init()	do { } while (0)
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* _ASM_IA64_PGTABLE_H */
diff -urN v2.4.19-pre10/include/asm-m68k/pgtable.h pageattr-v2.4.19-pre10.diff/include/asm-m68k/pgtable.h
--- v2.4.19-pre10/include/asm-m68k/pgtable.h	Mon Nov 12 17:49:51 2001
+++ pageattr-v2.4.19-pre10.diff/include/asm-m68k/pgtable.h	Tue Jun 11 22:18:14 2002
@@ -187,4 +187,6 @@
  */
 #define pgtable_cache_init()	do { } while (0)
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* _M68K_PGTABLE_H */
diff -urN v2.4.19-pre10/include/asm-mips/pgtable.h pageattr-v2.4.19-pre10.diff/include/asm-mips/pgtable.h
--- v2.4.19-pre10/include/asm-mips/pgtable.h	Thu Jun  6 20:10:09 2002
+++ pageattr-v2.4.19-pre10.diff/include/asm-mips/pgtable.h	Tue Jun 11 22:18:24 2002
@@ -538,4 +538,6 @@
  */
 #define pgtable_cache_init()	do { } while (0)
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* _ASM_PGTABLE_H */
diff -urN v2.4.19-pre10/include/asm-mips64/pgtable.h pageattr-v2.4.19-pre10.diff/include/asm-mips64/pgtable.h
--- v2.4.19-pre10/include/asm-mips64/pgtable.h	Thu Jun  6 20:10:10 2002
+++ pageattr-v2.4.19-pre10.diff/include/asm-mips64/pgtable.h	Tue Jun 11 22:18:20 2002
@@ -566,6 +566,8 @@
 
 #include <asm-generic/pgtable.h>
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* !defined (_LANGUAGE_ASSEMBLY) */
 
 #endif /* _ASM_PGTABLE_H */
diff -urN v2.4.19-pre10/include/asm-parisc/pgtable.h pageattr-v2.4.19-pre10.diff/include/asm-parisc/pgtable.h
--- v2.4.19-pre10/include/asm-parisc/pgtable.h	Thu Jun  6 20:10:10 2002
+++ pageattr-v2.4.19-pre10.diff/include/asm-parisc/pgtable.h	Tue Jun 11 22:18:32 2002
@@ -338,4 +338,6 @@
  */
 #define pgtable_cache_init()	do { } while (0)
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* _PARISC_PAGE_H */
diff -urN v2.4.19-pre10/include/asm-ppc/pgtable.h pageattr-v2.4.19-pre10.diff/include/asm-ppc/pgtable.h
--- v2.4.19-pre10/include/asm-ppc/pgtable.h	Thu Jun  6 20:10:10 2002
+++ pageattr-v2.4.19-pre10.diff/include/asm-ppc/pgtable.h	Tue Jun 11 22:18:43 2002
@@ -556,6 +556,8 @@
  */
 #define pgtable_cache_init()	do { } while (0)
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* __ASSEMBLY__ */
 #endif /* _PPC_PGTABLE_H */
 #endif /* __KERNEL__ */
diff -urN v2.4.19-pre10/include/asm-ppc64/pgtable.h pageattr-v2.4.19-pre10.diff/include/asm-ppc64/pgtable.h
--- v2.4.19-pre10/include/asm-ppc64/pgtable.h	Thu Jun  6 20:10:10 2002
+++ pageattr-v2.4.19-pre10.diff/include/asm-ppc64/pgtable.h	Tue Jun 11 22:18:39 2002
@@ -440,5 +440,7 @@
 extern void make_pte(HPTE * htab, unsigned long va, unsigned long pa,
 		int mode, unsigned long hash_mask, int large);
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* __ASSEMBLY__ */
 #endif /* _PPC64_PGTABLE_H */
diff -urN v2.4.19-pre10/include/asm-s390/pgtable.h pageattr-v2.4.19-pre10.diff/include/asm-s390/pgtable.h
--- v2.4.19-pre10/include/asm-s390/pgtable.h	Thu Jun  6 20:10:10 2002
+++ pageattr-v2.4.19-pre10.diff/include/asm-s390/pgtable.h	Tue Jun 11 22:18:47 2002
@@ -503,5 +503,7 @@
  */
 #define pgtable_cache_init()	do { } while (0)
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* _S390_PAGE_H */
 
diff -urN v2.4.19-pre10/include/asm-s390x/pgtable.h pageattr-v2.4.19-pre10.diff/include/asm-s390x/pgtable.h
--- v2.4.19-pre10/include/asm-s390x/pgtable.h	Thu Jun  6 20:10:10 2002
+++ pageattr-v2.4.19-pre10.diff/include/asm-s390x/pgtable.h	Tue Jun 11 22:18:50 2002
@@ -523,5 +523,7 @@
  */
 #define pgtable_cache_init()	do { } while (0)
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* _S390_PAGE_H */
 
diff -urN v2.4.19-pre10/include/asm-sh/pgtable.h pageattr-v2.4.19-pre10.diff/include/asm-sh/pgtable.h
--- v2.4.19-pre10/include/asm-sh/pgtable.h	Thu Jun  6 20:10:10 2002
+++ pageattr-v2.4.19-pre10.diff/include/asm-sh/pgtable.h	Tue Jun 11 22:18:57 2002
@@ -310,4 +310,6 @@
  */
 #define pgtable_cache_init()	do { } while (0)
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* __ASM_SH_PAGE_H */
diff -urN v2.4.19-pre10/include/asm-sparc/pgtable.h pageattr-v2.4.19-pre10.diff/include/asm-sparc/pgtable.h
--- v2.4.19-pre10/include/asm-sparc/pgtable.h	Thu Jun  6 20:10:10 2002
+++ pageattr-v2.4.19-pre10.diff/include/asm-sparc/pgtable.h	Tue Jun 11 22:19:05 2002
@@ -458,4 +458,6 @@
  */
 #define pgtable_cache_init()	do { } while (0)
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* !(_SPARC_PGTABLE_H) */
diff -urN v2.4.19-pre10/include/asm-sparc64/pgtable.h pageattr-v2.4.19-pre10.diff/include/asm-sparc64/pgtable.h
--- v2.4.19-pre10/include/asm-sparc64/pgtable.h	Thu Jun  6 20:10:10 2002
+++ pageattr-v2.4.19-pre10.diff/include/asm-sparc64/pgtable.h	Tue Jun 11 22:19:00 2002
@@ -357,4 +357,6 @@
  */
 #define pgtable_cache_init()	do { } while (0)
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* !(_SPARC64_PGTABLE_H) */

Re: [patch] pageattr update

[Andi Kleen]

On Wed, Jun 12, 2002 at 07:04:43AM +0200, Benjamin LaHaise wrote:
> Below are some updates to the pageattr patch you posted earlier.  The 
> first set of changes were to add change_page_attrs in several paths 
> where the AGP and DRM code would allocate a page and then call 
> ioremap_nocache on it to create an uncachable mapping.  Secondly, I 

I don't think these changes are needed. The GART tables itself have no physical
alias and the CPU AFAIK deals fine with virtual aliases.

> removed the #ifdef __i386__ around the change_page_attr hook, and 
> instead put dummy macros in the headers for the various other archs.  
> There was a race in pageattr.c that would make the P4 unhappy, so I 
> moved the pte page free to after the tlb flush.  The tlb flush was 

I had already fixed that, but thanks.

> not flushing global pages, so I replaced the code with a call to 
> flush_tlb_all() to do the job.  Lastly, since the top page of the 
> page tables on x86 is unique to each mm and contains copies of the 
> pmd entries in non-PAE mode, I added a function to walk all mms via 
> the mmlist to update the pmds before the tlb flush.

Urks. last version was only tested on PAE @)

Will release a new version tomorrow.

-Andi

Re: [patch] pageattr update

[Benjamin LaHaise]

On Thu, Jun 13, 2002 at 12:52:38AM +0200, Andi Kleen wrote:
> I don't think these changes are needed. The GART tables itself have no 
> physical alias and the CPU AFAIK deals fine with virtual aliases.

The problem is that this causes cache type aliases -- the CPU does not 
perform the cache coherency protocol for uncachable writes, iiuc.

> Will release a new version tomorrow.

A few more fixes and cleanups in my -C0 version below: make use of set_pmd 
as that makes the 64 bit updates correctly atomic on PAE, check the type of 
the old pte before decrementing the usage count on the split page (otherwise 
two change_page_attrs back to normal cachability state would corrupt the 
usage count), mark a merged 4MB page as global, use pte_same instead of 
memcmp, and some general tidy ups.

		-ben
-- 
"You will be reincarnated as a toad; and you will be much happier."

:r ~/patches/v2.4/v2.4.19-pre10-pageattr-C0.diff
diff -urN v2.4.19-pre10/arch/i386/mm/Makefile pageattr-C0-v2.4.19-pre10.diff/arch/i386/mm/Makefile
--- v2.4.19-pre10/arch/i386/mm/Makefile	Fri Dec 29 17:07:20 2000
+++ pageattr-C0-v2.4.19-pre10.diff/arch/i386/mm/Makefile	Tue Jun 11 21:41:54 2002
@@ -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 -urN v2.4.19-pre10/arch/i386/mm/pageattr.c pageattr-C0-v2.4.19-pre10.diff/arch/i386/mm/pageattr.c
--- v2.4.19-pre10/arch/i386/mm/pageattr.c	Wed Dec 31 19:00:00 1969
+++ pageattr-C0-v2.4.19-pre10.diff/arch/i386/mm/pageattr.c	Thu Jun 13 05:54:25 2002
@@ -0,0 +1,176 @@
+/*
+ * Copyright 2002 Andi Kleen, SuSE Labs.
+ * Copyright 2002 Red Hat, Inc.
+ * Additional fixes by Benjamin LaHaise, Red Hat.
+ */
+
+#include <linux/config.h>
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/highmem.h>
+#include <linux/module.h>
+#include <asm/uaccess.h>
+#include <asm/processor.h>
+
+/* Should move most of this stuff into the appropiate includes */
+#define PAGE_LARGE (_PAGE_PSE|_PAGE_PRESENT)
+#define LARGE_PAGE_MASK (~(LARGE_PAGE_SIZE-1))
+#define LARGE_PAGE_SIZE ((1UL << PMD_SHIFT))
+
+#ifdef CONFIG_DISCONTIGMEM
+#error you lose. sorry.
+#endif
+
+#ifdef CONFIG_X86_PAE
+/* note: PAT must be cleared also. assumes a PAE CPU also has PGE. */
+#define PAGE_KERNEL_4K \
+	__pgprot(_KERNPG_TABLE & ~(_PAGE_GLOBAL|_PAGE_DIRTY))
+#else
+#define PAGE_KERNEL_4K \
+	MAKE_GLOBAL(_KERNPG_TABLE & ~(_PAGE_DIRTY))
+#endif
+
+/*
+ * Update all kernel pmd entries in the system for the given address.
+ */
+static void update_all_kernel_pmds(unsigned long address, pmd_t new_pmd)
+{
+	/* PAE can avoid this operation as all mms share the same
+	 * kernel pmds, so the update will propagate when the TLBs
+	 * are flushed.
+	 */
+#if !defined(CONFIG_HIGHMEM64G)
+	struct mm_struct *mm = &init_mm;
+
+	spin_lock(&mmlist_lock);
+	for (;;) {
+		pmd_t *pmdp;
+		mm = list_entry(mm->mmlist.next, struct mm_struct, mmlist);
+		if (mm == &init_mm)
+			break;
+
+		pmdp = pmd_offset(pgd_offset(mm, address), address);
+		set_pmd(pmdp, new_pmd);
+	}
+	spin_unlock(&mmlist_lock);
+#endif
+	return;
+}
+
+static int split_large_page(pmd_t *pmdp, unsigned long address, pgprot_t prot)
+{
+	unsigned long addr, paddress;
+	int i;
+	pte_t *base = (pte_t *) __get_free_page(GFP_KERNEL);
+	if (!base)
+		return -ENOMEM;
+
+	BUG_ON(atomic_read(&virt_to_page(base)->count) != 1); 	
+	paddress = __pa(address);
+	addr = paddress & LARGE_PAGE_MASK;
+	for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE) {
+		base[i] = mk_pte_phys(addr,
+				      addr == paddress ? prot : PAGE_KERNEL);
+	}
+
+	set_pmd(pmdp, mk_pmd(virt_to_page(base), PAGE_KERNEL_4K));
+	update_all_kernel_pmds(address, *pmdp);
+	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.
+ * When page is in highmem it must never be kmap'ed.
+ */
+int change_page_attr(struct page *page, pgprot_t prot)
+{
+	int err = 0;
+	struct page *page_to_free = NULL;
+	struct page *kpte_page;
+	unsigned long address;
+	pgd_t *pgdp;
+	pmd_t *pmdp;
+
+#ifdef CONFIG_HIGHMEM
+	if (page >= highmem_start_page) {
+		/* Hopefully not be mapped anywhere else. */
+		return 0;
+	}
+#endif
+
+	address = ((unsigned long)(page - mem_map) << PAGE_SHIFT) + __PAGE_OFFSET;
+
+	down_write(&init_mm.mmap_sem);
+	pgdp = pgd_offset(&init_mm, address);
+	if (!pgd_present(*pgdp))
+		BUG();
+
+	pmdp = pmd_offset(pgdp, address);
+	if (!pmd_present(*pmdp))
+		BUG();
+
+	kpte_page = virt_to_page(pmd_page(*pmdp));
+	if (pgprot_val(prot) != pgprot_val(PAGE_KERNEL)) {
+		if ((pmd_val(*pmdp) & _PAGE_PSE) == 0) {
+			pte_t *ptep = pte_offset(pmdp, address);
+			pte_t old = *ptep, standard = mk_pte(page, PAGE_KERNEL);
+			/* Already a 4KB page. Just update it to the new
+			 * protection.  Doesn't need to be atomic. It doesn't
+			 * matter if dirty bits get lost, they're already
+			 * set in for kernel pages.
+			 */
+			set_pte(ptep, mk_pte(page, prot));
+			if (pte_same(old, standard))
+				atomic_inc(&kpte_page->count);
+		} else {
+			err = split_large_page(pmdp, address, prot);
+			if (err)
+				goto out;
+		}	
+	} else if ((pmd_val(*pmdp) & _PAGE_PSE) == 0) {
+		pte_t *ptep = pte_offset(pmdp, address);
+		pte_t standard = mk_pte(page, PAGE_KERNEL);
+
+		/* If this mapping is already a standard kernel mapping,
+		 * we have nothing to do.
+		 */
+		if (pte_same(*ptep, standard))
+			goto out;
+
+		/* just an ordinary page again - revert to standard mapping */	
+		set_pte(ptep, standard);
+		atomic_dec(&kpte_page->count);
+		if (cpu_has_pse && (atomic_read(&kpte_page->count) == 1)) {
+			/* no more special protections in this 4MB area -
+			 * revert to a large page again.
+			 */
+			set_pmd(pmdp,
+				mk_pmd_phys(__pa(address & LARGE_PAGE_MASK),
+					    MAKE_GLOBAL(_KERNPG_TABLE|_PAGE_PSE)));
+			update_all_kernel_pmds(address, *pmdp);
+			page_to_free = kpte_page;
+		}
+	}
+
+	/* Kernel pages typically have the global bit set, so we must
+	 * flush everything...
+	 */
+	flush_tlb_all();
+
+	if (NULL != page_to_free)
+		__free_page(page_to_free);
+	err = 0;
+out:
+	up_write(&init_mm.mmap_sem);
+	return err;
+}
+
+EXPORT_SYMBOL(change_page_attr);
diff -urN v2.4.19-pre10/drivers/char/agp/agpgart_be.c pageattr-C0-v2.4.19-pre10.diff/drivers/char/agp/agpgart_be.c
--- v2.4.19-pre10/drivers/char/agp/agpgart_be.c	Thu Jun  6 20:09:59 2002
+++ pageattr-C0-v2.4.19-pre10.diff/drivers/char/agp/agpgart_be.c	Tue Jun 11 22:08:48 2002
@@ -397,7 +397,7 @@
 static void agp_generic_agp_enable(u32 mode)
 {
 	struct pci_dev *device = NULL;
-	u32 command, scratch, cap_id;
+	u32 command, scratch;
 	u8 cap_ptr;
 
 	pci_read_config_dword(agp_bridge.dev,
@@ -561,6 +561,7 @@
 					    agp_bridge.current_size;
 					break;
 				}
+				temp = agp_bridge.current_size;
 			} else {
 				agp_bridge.aperture_size_idx = i;
 			}
@@ -578,8 +579,10 @@
 	}
 	table_end = table + ((PAGE_SIZE * (1 << page_order)) - 1);
 
-	for (page = virt_to_page(table); page <= virt_to_page(table_end); page++)
+	for (page = virt_to_page(table); page <= virt_to_page(table_end); page++) {
 		SetPageReserved(page);
+		change_page_attr(page, __pgprot(__PAGE_KERNEL | _PAGE_PCD));
+	}
 
 	agp_bridge.gatt_table_real = (unsigned long *) table;
 	CACHE_FLUSH();
@@ -588,8 +591,10 @@
 	CACHE_FLUSH();
 
 	if (agp_bridge.gatt_table == NULL) {
-		for (page = virt_to_page(table); page <= virt_to_page(table_end); page++)
+		for (page = virt_to_page(table); page <= virt_to_page(table_end); page++) {
+			change_page_attr(page, PAGE_KERNEL);
 			ClearPageReserved(page);
+		}
 
 		free_pages((unsigned long) table, page_order);
 
@@ -655,8 +660,10 @@
 	table = (char *) agp_bridge.gatt_table_real;
 	table_end = table + ((PAGE_SIZE * (1 << page_order)) - 1);
 
-	for (page = virt_to_page(table); page <= virt_to_page(table_end); page++)
+	for (page = virt_to_page(table); page <= virt_to_page(table_end); page++) {
+		change_page_attr(page, PAGE_KERNEL);
 		ClearPageReserved(page);
+	}
 
 	free_pages((unsigned long) agp_bridge.gatt_table_real, page_order);
 	return 0;
@@ -769,6 +776,8 @@
 	if (page == NULL) {
 		return 0;
 	}
+	change_page_attr(page, __pgprot(__PAGE_KERNEL | _PAGE_PCD));
+
 	get_page(page);
 	LockPage(page);
 	atomic_inc(&agp_bridge.current_memory_agp);
@@ -785,6 +794,9 @@
 	}
 	
 	page = virt_to_page(pt);
+	change_page_attr(page, PAGE_KERNEL);
+	
+
 	put_page(page);
 	UnlockPage(page);
 	free_page((unsigned long) pt);
@@ -2243,9 +2255,11 @@
 	}
 	SetPageReserved(virt_to_page(page_map->real));
 	CACHE_FLUSH();
+	change_page_attr(virt_to_page(page_map->real), __pgprot(__PAGE_KERNEL | _PAGE_PCD));
 	page_map->remapped = ioremap_nocache(virt_to_phys(page_map->real), 
 					    PAGE_SIZE);
 	if (page_map->remapped == NULL) {
+		change_page_attr(virt_to_page(page_map->real), PAGE_KERNEL);
 		ClearPageReserved(virt_to_page(page_map->real));
 		free_page((unsigned long) page_map->real);
 		page_map->real = NULL;
@@ -2263,6 +2277,7 @@
 static void amd_free_page_map(amd_page_map *page_map)
 {
 	iounmap(page_map->remapped);
+	change_page_attr(virt_to_page(page_map->real), PAGE_KERNEL);
 	ClearPageReserved(virt_to_page(page_map->real));
 	free_page((unsigned long) page_map->real);
 }
@@ -2744,27 +2759,22 @@
 
 static unsigned long ali_alloc_page(void)
 {
-	struct page *page;
-	u32 temp;
-
-	page = alloc_page(GFP_KERNEL);
-	if (page == NULL)
+	unsigned long p = agp_generic_alloc_page(); 
+	if (!p) 
 		return 0;
 
-	get_page(page);
-	LockPage(page);
-	atomic_inc(&agp_bridge.current_memory_agp);
-
+	/* probably not needed anymore */
 	global_cache_flush();
 
 	if (agp_bridge.type == ALI_M1541) {
+		u32 temp;
 		pci_read_config_dword(agp_bridge.dev, ALI_CACHE_FLUSH_CTRL, &temp);
 		pci_write_config_dword(agp_bridge.dev, ALI_CACHE_FLUSH_CTRL,
 				(((temp & ALI_CACHE_FLUSH_ADDR_MASK) |
-				  virt_to_phys(page_address(page))) |
+				  virt_to_phys(p)) |
 				    ALI_CACHE_FLUSH_EN ));
 	}
-	return (unsigned long)page_address(page);
+	return p;
 }
 
 static void ali_destroy_page(unsigned long addr)
@@ -2786,11 +2796,7 @@
 				    ALI_CACHE_FLUSH_EN));
 	}
 
-	page = virt_to_page(pt);
-	put_page(page);
-	UnlockPage(page);
-	free_page((unsigned long) pt);
-	atomic_dec(&agp_bridge.current_memory_agp);
+	agp_generic_destroy_page(pt);
 }
 
 /* Setup function */
@@ -2872,9 +2878,11 @@
 	}
 	SetPageReserved(virt_to_page(page_map->real));
 	CACHE_FLUSH();
+	change_page_attr(virt_to_page(page_map->real), __pgprot(__PAGE_KERNEL | _PAGE_PCD));
 	page_map->remapped = ioremap_nocache(virt_to_phys(page_map->real), 
 					    PAGE_SIZE);
 	if (page_map->remapped == NULL) {
+		change_page_attr(virt_to_page(page_map->real), PAGE_KERNEL);
 		ClearPageReserved(virt_to_page(page_map->real));
 		free_page((unsigned long) page_map->real);
 		page_map->real = NULL;
@@ -2892,6 +2900,7 @@
 static void serverworks_free_page_map(serverworks_page_map *page_map)
 {
 	iounmap(page_map->remapped);
+	change_page_attr(virt_to_page(page_map->real), PAGE_KERNEL);
 	ClearPageReserved(virt_to_page(page_map->real));
 	free_page((unsigned long) page_map->real);
 }
diff -urN v2.4.19-pre10/drivers/char/drm-4.0/mga_dma.c pageattr-C0-v2.4.19-pre10.diff/drivers/char/drm-4.0/mga_dma.c
--- v2.4.19-pre10/drivers/char/drm-4.0/mga_dma.c	Thu Mar  7 16:39:58 2002
+++ pageattr-C0-v2.4.19-pre10.diff/drivers/char/drm-4.0/mga_dma.c	Tue Jun 11 22:01:01 2002
@@ -641,6 +641,7 @@
 		   	iounmap(dev_priv->status_page);
 		}
 	   	if(dev_priv->real_status_page != 0UL) {
+			change_page_attr(virt_to_page(dev_priv->real_status_page), PAGE_KERNEL);
 		   	mga_free_page(dev, dev_priv->real_status_page);
 		}
 	   	if(dev_priv->prim_bufs != NULL) {
@@ -731,6 +732,7 @@
 		return -ENOMEM;
 	}
 
+	change_page_attr(virt_to_page(dev_priv->real_status_page), __pgprot(__PAGE_KERNEL | _PAGE_PCD));
    	dev_priv->status_page =
 		ioremap_nocache(virt_to_bus((void *)dev_priv->real_status_page),
 				PAGE_SIZE);
diff -urN v2.4.19-pre10/include/asm-alpha/pgtable.h pageattr-C0-v2.4.19-pre10.diff/include/asm-alpha/pgtable.h
--- v2.4.19-pre10/include/asm-alpha/pgtable.h	Thu Jun  6 20:10:08 2002
+++ pageattr-C0-v2.4.19-pre10.diff/include/asm-alpha/pgtable.h	Tue Jun 11 22:17:39 2002
@@ -364,4 +364,6 @@
 /* We have our own get_unmapped_area to cope with ADDR_LIMIT_32BIT.  */
 #define HAVE_ARCH_UNMAPPED_AREA
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* _ALPHA_PGTABLE_H */
diff -urN v2.4.19-pre10/include/asm-arm/pgtable.h pageattr-C0-v2.4.19-pre10.diff/include/asm-arm/pgtable.h
--- v2.4.19-pre10/include/asm-arm/pgtable.h	Thu Jun  6 20:10:08 2002
+++ pageattr-C0-v2.4.19-pre10.diff/include/asm-arm/pgtable.h	Tue Jun 11 22:17:48 2002
@@ -175,6 +175,7 @@
 #include <asm-generic/pgtable.h>
 
 extern void pgtable_cache_init(void);
+#define change_page_attr(page, prot)	do { } while (0)
 
 #endif /* !__ASSEMBLY__ */
 
diff -urN v2.4.19-pre10/include/asm-cris/pgtable.h pageattr-C0-v2.4.19-pre10.diff/include/asm-cris/pgtable.h
--- v2.4.19-pre10/include/asm-cris/pgtable.h	Thu Jun  6 20:10:08 2002
+++ pageattr-C0-v2.4.19-pre10.diff/include/asm-cris/pgtable.h	Tue Jun 11 22:17:59 2002
@@ -520,4 +520,6 @@
  */
 #define pgtable_cache_init()   do { } while (0)
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* _CRIS_PGTABLE_H */
diff -urN v2.4.19-pre10/include/asm-i386/pgtable.h pageattr-C0-v2.4.19-pre10.diff/include/asm-i386/pgtable.h
--- v2.4.19-pre10/include/asm-i386/pgtable.h	Thu Jun  6 20:10:08 2002
+++ pageattr-C0-v2.4.19-pre10.diff/include/asm-i386/pgtable.h	Thu Jun 13 05:55:41 2002
@@ -312,6 +312,8 @@
 
 #define page_pte(page) page_pte_prot(page, __pgprot(0))
 
+#define mk_pmd(page, prot)	__pmd(pte_val(mk_pte(page,prot)))
+#define mk_pmd_phys(page, prot)	__pmd(pte_val(mk_pte_phys(page,prot)))
 #define pmd_page(pmd) \
 ((unsigned long) __va(pmd_val(pmd) & PAGE_MASK))
 
@@ -347,6 +349,9 @@
 #define pte_to_swp_entry(pte)		((swp_entry_t) { (pte).pte_low })
 #define swp_entry_to_pte(x)		((pte_t) { (x).val })
 
+struct page;
+int change_page_attr(struct page *, pgprot_t prot);
+
 #endif /* !__ASSEMBLY__ */
 
 /* Needs to be defined here and not in linux/mm.h, as it is arch dependent */
diff -urN v2.4.19-pre10/include/asm-ia64/pgtable.h pageattr-C0-v2.4.19-pre10.diff/include/asm-ia64/pgtable.h
--- v2.4.19-pre10/include/asm-ia64/pgtable.h	Thu Jun  6 20:10:08 2002
+++ pageattr-C0-v2.4.19-pre10.diff/include/asm-ia64/pgtable.h	Tue Jun 11 22:18:10 2002
@@ -473,4 +473,6 @@
  */
 #define pgtable_cache_init()	do { } while (0)
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* _ASM_IA64_PGTABLE_H */
diff -urN v2.4.19-pre10/include/asm-m68k/pgtable.h pageattr-C0-v2.4.19-pre10.diff/include/asm-m68k/pgtable.h
--- v2.4.19-pre10/include/asm-m68k/pgtable.h	Mon Nov 12 17:49:51 2001
+++ pageattr-C0-v2.4.19-pre10.diff/include/asm-m68k/pgtable.h	Tue Jun 11 22:18:14 2002
@@ -187,4 +187,6 @@
  */
 #define pgtable_cache_init()	do { } while (0)
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* _M68K_PGTABLE_H */
diff -urN v2.4.19-pre10/include/asm-mips/pgtable.h pageattr-C0-v2.4.19-pre10.diff/include/asm-mips/pgtable.h
--- v2.4.19-pre10/include/asm-mips/pgtable.h	Thu Jun  6 20:10:09 2002
+++ pageattr-C0-v2.4.19-pre10.diff/include/asm-mips/pgtable.h	Tue Jun 11 22:18:24 2002
@@ -538,4 +538,6 @@
  */
 #define pgtable_cache_init()	do { } while (0)
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* _ASM_PGTABLE_H */
diff -urN v2.4.19-pre10/include/asm-mips64/pgtable.h pageattr-C0-v2.4.19-pre10.diff/include/asm-mips64/pgtable.h
--- v2.4.19-pre10/include/asm-mips64/pgtable.h	Thu Jun  6 20:10:10 2002
+++ pageattr-C0-v2.4.19-pre10.diff/include/asm-mips64/pgtable.h	Tue Jun 11 22:18:20 2002
@@ -566,6 +566,8 @@
 
 #include <asm-generic/pgtable.h>
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* !defined (_LANGUAGE_ASSEMBLY) */
 
 #endif /* _ASM_PGTABLE_H */
diff -urN v2.4.19-pre10/include/asm-parisc/pgtable.h pageattr-C0-v2.4.19-pre10.diff/include/asm-parisc/pgtable.h
--- v2.4.19-pre10/include/asm-parisc/pgtable.h	Thu Jun  6 20:10:10 2002
+++ pageattr-C0-v2.4.19-pre10.diff/include/asm-parisc/pgtable.h	Tue Jun 11 22:18:32 2002
@@ -338,4 +338,6 @@
  */
 #define pgtable_cache_init()	do { } while (0)
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* _PARISC_PAGE_H */
diff -urN v2.4.19-pre10/include/asm-ppc/pgtable.h pageattr-C0-v2.4.19-pre10.diff/include/asm-ppc/pgtable.h
--- v2.4.19-pre10/include/asm-ppc/pgtable.h	Thu Jun  6 20:10:10 2002
+++ pageattr-C0-v2.4.19-pre10.diff/include/asm-ppc/pgtable.h	Tue Jun 11 22:18:43 2002
@@ -556,6 +556,8 @@
  */
 #define pgtable_cache_init()	do { } while (0)
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* __ASSEMBLY__ */
 #endif /* _PPC_PGTABLE_H */
 #endif /* __KERNEL__ */
diff -urN v2.4.19-pre10/include/asm-ppc64/pgtable.h pageattr-C0-v2.4.19-pre10.diff/include/asm-ppc64/pgtable.h
--- v2.4.19-pre10/include/asm-ppc64/pgtable.h	Thu Jun  6 20:10:10 2002
+++ pageattr-C0-v2.4.19-pre10.diff/include/asm-ppc64/pgtable.h	Tue Jun 11 22:18:39 2002
@@ -440,5 +440,7 @@
 extern void make_pte(HPTE * htab, unsigned long va, unsigned long pa,
 		int mode, unsigned long hash_mask, int large);
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* __ASSEMBLY__ */
 #endif /* _PPC64_PGTABLE_H */
diff -urN v2.4.19-pre10/include/asm-s390/pgtable.h pageattr-C0-v2.4.19-pre10.diff/include/asm-s390/pgtable.h
--- v2.4.19-pre10/include/asm-s390/pgtable.h	Thu Jun  6 20:10:10 2002
+++ pageattr-C0-v2.4.19-pre10.diff/include/asm-s390/pgtable.h	Tue Jun 11 22:18:47 2002
@@ -503,5 +503,7 @@
  */
 #define pgtable_cache_init()	do { } while (0)
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* _S390_PAGE_H */
 
diff -urN v2.4.19-pre10/include/asm-s390x/pgtable.h pageattr-C0-v2.4.19-pre10.diff/include/asm-s390x/pgtable.h
--- v2.4.19-pre10/include/asm-s390x/pgtable.h	Thu Jun  6 20:10:10 2002
+++ pageattr-C0-v2.4.19-pre10.diff/include/asm-s390x/pgtable.h	Tue Jun 11 22:18:50 2002
@@ -523,5 +523,7 @@
  */
 #define pgtable_cache_init()	do { } while (0)
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* _S390_PAGE_H */
 
diff -urN v2.4.19-pre10/include/asm-sh/pgtable.h pageattr-C0-v2.4.19-pre10.diff/include/asm-sh/pgtable.h
--- v2.4.19-pre10/include/asm-sh/pgtable.h	Thu Jun  6 20:10:10 2002
+++ pageattr-C0-v2.4.19-pre10.diff/include/asm-sh/pgtable.h	Tue Jun 11 22:18:57 2002
@@ -310,4 +310,6 @@
  */
 #define pgtable_cache_init()	do { } while (0)
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* __ASM_SH_PAGE_H */
diff -urN v2.4.19-pre10/include/asm-sparc/pgtable.h pageattr-C0-v2.4.19-pre10.diff/include/asm-sparc/pgtable.h
--- v2.4.19-pre10/include/asm-sparc/pgtable.h	Thu Jun  6 20:10:10 2002
+++ pageattr-C0-v2.4.19-pre10.diff/include/asm-sparc/pgtable.h	Tue Jun 11 22:19:05 2002
@@ -458,4 +458,6 @@
  */
 #define pgtable_cache_init()	do { } while (0)
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* !(_SPARC_PGTABLE_H) */
diff -urN v2.4.19-pre10/include/asm-sparc64/pgtable.h pageattr-C0-v2.4.19-pre10.diff/include/asm-sparc64/pgtable.h
--- v2.4.19-pre10/include/asm-sparc64/pgtable.h	Thu Jun  6 20:10:10 2002
+++ pageattr-C0-v2.4.19-pre10.diff/include/asm-sparc64/pgtable.h	Tue Jun 11 22:19:00 2002
@@ -357,4 +357,6 @@
  */
 #define pgtable_cache_init()	do { } while (0)
 
+#define change_page_attr(page, prot)	do { } while (0)
+
 #endif /* !(_SPARC64_PGTABLE_H) */

Re: [patch] pageattr update

[David Mosberger]

Hi Ben,

I'm have a concern about the current change_page_attr() patch.  It
gives the impression that the GART memory always gets mapped
write-combined.  This is not always true.  For example, on IA-64,
attribute-aliasing issues are prevented by requiring IA-64 platforms
to use coherent AGP DMA.  In other words, the AGP memory will be
mapped writeback, as usual.

As long as change_page_attr() is used for AGP-related stuff only,
there is probably no real issue with the patch in its current form
(its simply a no-op on most non-x86 platforms).  However, I'm a bit
worried that someone might start to use it for other things, such that
change_page_attr() could no longer be a no-op on those platforms.
Since the DMA coherency issue is an AGP specific issue, perhaps just
renaming the macro to agp_change_page_attr() would take care of my
concern.  What do you think?

	--david

Re: [patch] pageattr update

[Andi Kleen]

David Mosberger <davidm@napali.hpl.hp.com> writes:

> As long as change_page_attr() is used for AGP-related stuff only,
> there is probably no real issue with the patch in its current form
> (its simply a no-op on most non-x86 platforms).  However, I'm a bit
> worried that someone might start to use it for other things, such that
> change_page_attr() could no longer be a no-op on those platforms.
> Since the DMA coherency issue is an AGP specific issue, perhaps just
> renaming the macro to agp_change_page_attr() would take care of my
> concern.  What do you think

Linus already requested that for 2.5 (agp_map_into_gart() etc.) 
I think for 2.4 #ifdef in the agp code is fine and I'm not adopting Ben's 
change of moving change_page_attr into all asm files.

-Andi